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Abstracts by Author62.2 ABGRALL, M-J.*, WALTERS, L.J.,University of Central Florida, Orlando. Settle-ment preferences and recruitment of thebryozoan Bugula neritina on driftmacroalgae in Mosquito Lagoon, Florida.

In Mosquito Lagoon (the northernmostregion of the Indian River Lagoon, Florida),significant differences in the abundance anddiversity of drift macroalgae were foundwhen sampled on a monthly basis from Janu-ary 1998 - March 2000. In the winter months,the arborescent bryozoan Bugula neritinawas commonly found attached to availabledrift species in the order Gigartinales,Rhodophycea. However, it was rarely foundon these same algal species when they wereattached. In replicated single and multiple-choice trials in the laboratory that includedthe seagrass Halodule wrightii and themacroalgae Hypnea cervicornis, Gracilariaarmata, Gracilaria tikvahiae, Enteromorphacompressa, Agardhiella subulata and Dasyarigidula, the two species of red algaeGracilaria were significantly preferred in bothtypes of trials. Despite having a similar mor-phology to G. armata, Dasya rigidula wasavoided by settling larvae of B. neritina andgreater than 60% larval mortality occurredin the bioassays. To determine if the preferredsettlement choice of B. neritina is due to themorphology of Gracilaria or secondarychemicals, field trials were run comparingrecruitment on attached versus drift G.armata and attached versus drift mimics.Bugula neritina never recruited on attachedG. armata and rarely on mimics (drift or at-tached); however, large numbers of larvaerecruited on drift G. armata.

P2.21ADAMS, J.A.*, MOORE, P.A., BowlingGreen State University, Bowling Green, OH.Attraction of conspecifics to molt signals incrayfish.

For many organisms olfaction plays a keyrole in communication. Crayfish use olfac-tory signals to find mates, warn of predators,and relay social status. While many of thesesituations have been studied in detail, be-

havior of conspecifics toward molted indi-viduals has not. The physiology of crayfishchanges dramatically during molting(ecdysis), which in turn changes both thecontent and concentrations of the chemicalcues released into the water. We hypoth-esized that conspecifics would pick up thesechanges in chemicals released and movetoward the molt signal. A Y-maze was usedto test for a differential attraction to variousodors presented to intermolt (non-molting)crayfish. All crayfish used were of the spe-cies Orconectes rusticus. The odor sourceswere molt crayfish, intermolt crayfish, agedtank water (control), or food (fish carrion).Variables measured included initial armchoice, time spent in each arm, walkingspeed toward source, meral spread, andstraightness of path. On average, crayfishspent more time the presence of molt sig-nals when paired with intermolt or controlstimuli. The food stimulus was more attrac-tive than over any of the other stimuli. Theseresults demonstrate that there is a differencein the way a conspecific perceives a recentlymolted individual versus an intermolt indi-vidual. Since cannabalism and aggressive-ness toward molted individuals has beenobserved in laboratory situations, the abilityof a conspecific to recognize a molted indi-vidual by olfaction has implications for bothsocial interactions and survival of individu-als in crayfish populations.

68.1 ADELMAN, L.M., Institute for Learn-ing Innovation, Annapolis, MD. Integrationof research and education: Are you ready?

Have you seen the new NSF guidelines?"One of the principal strategies in support ofNSF's goals is to foster integration of re-search and education through the programs,projects, and activities it supports at aca-demic and research institutions....NSF iscommitted to this principle of diversity anddeems it central to the programs, projects,and activities it considers and supports." Thesubtext is that NSF, as well as other fundingsources and professionals worldwide, are

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embracing the tremendous value, benefit,and responsibility of the scientific commu-nity to facilitate the utilization of their research,resources, and expertise in educational out-reach! This talk will explore the benefits andchallenges of scientists involvement in pub-lic education, with particular emphasis onidentifying and exploring existing commu-nity outreach needs, effective strategies, andpartnerships.

S3.5 AERTS, P.*, VAN DAMME, J.,HERREL, A., University of Antwerp (UIA),Belgium. Intrinsic mechanics and control offast cranio-cervical movements in aquaticfeeding turtles.

Aquatic feeding strikes on agile prey insnake-necked turtles involves fast neck ex-tension, bucco-pharyngo-oesophageal ex-pansion and head retraction. The ultimate,rectilinear acceleration of the head towardsthe prey requires complex vertebral rota-tions, largely differing from strike to strike.This poses serious control-demands to thenumerous intrinsic neck-muscles which arethe sole neck extensors. Mathematical mod-elling shows, however, that extensor activitymight be redundant for this phase of thestrike. The ultimate head acceleration al-ways goes along with forceful bucco-pha-ryngeal expansion. The momentum of thethus induced suction flow suffices to pull thehead (and the neck) straight towards theprey. The global control of this buccal ex-pansion proceeds identically to what is ob-served in primary aquatic feeders : througha rostro-caudal expansion sequence char-acterized by an optimal timing of the func-tional components supporting the expansionwave. Yet, distinct structural solutions, bothat the skeletal and muscular level, are in-volved. This points towards prominent hy-drodynamic constraints. Extrinsic neckmuscles retract the head and neck. Giventhe high number of degrees of freedom, thismusculo-skeletal system is obviously under-determined which compromises control. Er-roneous neck folding might be avoidedthrough the presence of a subtle click sys-tem at the level of the joint between cervical5 and 6.

24.4 AHN, A.N., University of California,Berkeley, CA. Using in vivo stimulation andstrain conditions to explain how two musclesfunction differently under identical condi-tions.

Even when experiencing identical strainand stimulation conditions, two leg musclesof the cockroach, Blaberus discoidalis, func-tion differently. Both muscles are innervatedby the same, single excitatory motor neu-ron, extend a single degree-of-freedom joint,and have similar twitch kinetics and similarforce-length and force-velocity propertieswhen maximally stimulated. When bothmuscles were strained cyclically and stimu-lated phasically under identical conditions(8 Hz; 15% strain; in vivo stimulation patterndetermined during running), muscle 178generated mechanical energy over a cycle(10.1 W kg-1; n = 5), while muscle 179 ab-sorbed net mechanical energy (-14.7 W kg-

1; n = 6). Forces generated during shorten-ing determined the main difference in me-chanical function between the two muscles.Although the force-length relationships ofmuscles 178 and 179 were similar whenmaximally stimulated, the force-length rela-tionships when submaximally stimulatedshowed that muscle 178 generated higherforces at shorter lengths than muscle 179.Differences between the two muscles in theirsubmaximal force-length relationships andin force enhancement after a passive stretchcould account for approximately 85% of thedifference in peak force generated betweenthe two muscles during oscillatory contrac-tions. Using the in vivo conditions and ex-amining the history-dependent properties ofthese muscles provide clues to how themuscles function differently under identicalcyclical conditions. Understanding the func-tional consequences of submaximal stimu-lation and contraction history can reveal dif-ferences in force generation that are notapparent during maximally stimulatedmuscle in isometric and isotonic measure-ments.

S11.12 ALEXANDER, R.McN., Universityof Leeds, England. Stability andmanoeuvrability of terrestrial vertebrates.

For a standing animal to be staticallystable, a vertical line through its centre of

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mass must pass through the polygon of sup-port defined by its feet. Statically stable gaitsare possible for quadrupeds but do not seemto be used; a discussion of turtles shows whythey may be disadvantageous. Physical andmathematical models have shown that pas-sive bipedal walking machines can be dy-namically stable for motion in the sagittalplane, but not in roll. Accelerations and de-celerations of animals may be limited bymuscle strength, by the coefficient of frictionwith the ground, or by considerations of sta-bility. Cornering ability similarly may be lim-ited by strength or by the coefficient of fric-tion. A simple mathematical model showsthat it may be faster to use a longer routewith corners of larger radius,than a shorterone with sharper corners. The concepts ofoversteer and understeer,as applied towheeled vehicles, may throw light on thestability of running.

S3.1 ALFARO, M.E.*, JANOVETZ, J., BLOB,R., WESTNEAT, M.W., Field Museum, Chi-cago. Biting in teleost fishes.

Biting is a distinct means of feeding infishes in which upper and lower jaws forc-ibly grasp, tear, or cut the prey. Biting is acommon mode of feeding in many groups offishes, including parrotfishes, wrasses,cichlids, triggerfishes, surgeonfishes, dam-selfishes, and characins, yet the kinematicsand motor patterns of this behavior have re-ceived relatively little attention compared tosuction feeding. To quantify the muscularmotor pattern of biting and to identify aspectsof it that appear to be phylogenetically con-served, we recorded activity from theepaxialis, levator operculi, sternohyoideus,and subdivisions of the adductormandibulae during the bite in species ofparrotfishes, wrasses, and serrasalminae. Inparrotfishes, significant species-level differ-ences were found in the duration and timingof muscle activity, suggesting that the motorcontrol of biting is evolutionarily plastic atrelatively low phylogenetic levels. To deter-mine if biting motor patterns differ signifi-cantly from suction feeding motor patterns,we used MANOVA and principal compo-nents analysis to compare EMGs of bitingand suction-feeding taxa. The multivariate

space occupied by biting and suction feed-ing is constrained by the motor control re-quirement of opening and then closing thejaws. However, biting in parrotfishes wassignificantly different than suction feeding inother teleosts, although there was a highdegree of overlap among all feeding strikes.Many biters also showed little or no epaxialisactivity, suggesting that, in contrast to suc-tion feeding, cranial elevation is relativelyunimportant in biting. ONR N000149910184and NSF DEB- 9815614.

P2.37ALKINDI, A.Y.A., MAHMOUD, I.Y., AL-GHEILANI, H.M.H., AL-HABSI, A.A.,ALKIYUMI, A.A., KHAN, H.*, Sultan QaboosUniversity, Oman, Sultan Qaboos University,Oman, Ministry of Agri. & Fish., Oman, Sul-tan Qaboos University, Oman, Ministry ofReg. Municip. & Environ., Oman, SultanQaboos University, Oman. The degree ofcrowding and its effect on the nesting be-havior in the green turtle Chelonia mydas inOman.

The nesting behavior of the greenturtle, Chelonia mydas, was observed dur-ing high population density period (June-October) and low population density period(Nov-May) in Ras Al-Hadd, Sultanate ofOman. Oman hosts one of the largest nest-ing populations in the world. The degree ofcrowding during the nesting season revealsome information on the way the turtles “ad-just” to the seasonal changes to some eco-logical factors such as the availability of nestsites, and the location of the nests relative tothe tidal zone. During low density, the turtlestend to build their nest away from the tidalzone and the frequency of nesting near orinside the tidal zone is low. During high den-sity, the frequency of choosing the nests nearor inside the tidal zone increases signifi-cantly even when there is less crowding andmore nesting areas are available in a givingnight. Based on these conditions, we sug-gest that the turtles become aware of thecrowding condition before they ascend onthe beaches as they gather near the nestinggrounds. The significant of such nesting strat-egy will be discussed.

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34.5 ALTSHULER, D.L.*, CHAI, P., Univer-sity of Texas at Austin. Hovering performanceof hummingbirds in hyperoxic gas mixtures.

We present a test of the hypothesis thatinspiration of hyperoxic air increases hum-mingbird hovering performance when birdsare challenged aerodynamically. We mea-sured the maximum duration of hoveringflight and the simultaneous oxygen con-sumption of ruby-throated hummingbirds(Archilochus colubris) in low density helioxthat was either normoxic (21% O2) orhyperoxic (35% O2). As density decreased,hummingbirds in hyperoxia significantly in-creased hovering duration, down to the den-sity at which birds could no longer sustainhovering flight. At this final density, skeletalmuscle activity appears to be anaerobic andindependent of oxygen concentration. Hum-mingbirds in hyperoxia showed no signifi-cant increase in oxygen consumption atlower densities. Additionally, we tested thebirds ability to discriminate between artifi-cial flowers infused with either normoxic orhyperoxic gases. Even after a full day of train-ing birds failed to associate oxygen concen-tration with a particular flower, independentof air density. Supplemental oxygen thusyields increased hovering duration but theminimum density at which birds can fly islimited exclusively by aerodynamic consid-erations.

69.1 AMUNDSON, R., University of Hawaiiat Hilo. Evo versus devo: methodologicalconflicts in the treatment of variation.

Evolutionary and developmental biologywere independent enterprises for most ofthe twentieth century. Differences in goalsled to differences and even inconsistenciesin methodologies and practices. One of thetasks of an integrative program of evolution-ary developmental biology will be to negoti-ate these inconsistencies. Among the mostdifficult may be conflicts in the ways varia-tion is dealt with. For example, the evolu-tionary antagonism towards typology maybe irreconcilable with such organizationaldevelopmental concepts as the Bauplan. Isit possible to be a population thinker whilesimultaneously conceiving of evolution aschanges in developmental processes?

24.2 ANDERSON, B.D.*, FULL, R.J.,GARCIA, M., University of California, Berke-ley, CA. A spring-mass model of centipedelocomotion.

The laterally undulating Arizona centi-pede, Scolopendra heros, uses ametachronal gait in which all legs on theconcave side of the bent body touch theground at a single point. Each leg of thewave of legs traveling through this point isnot on the ground for a long enough periodto aid in understanding centipede locomo-tor dynamics. However, as a wave of legstravels through this one point of ground con-tact, the individual legs combine to gener-ate ground reaction forces (GRFs) and me-chanical energies (MEs) of the center of massthat are similar to a spring. This is analo-gous to the spring-like behavior of all legs incontact with the ground at a time, or the “vir-tual leg,” in symmetrical gaits. We modeleach wave of centipede legs as a “virtualwave-spring.” Centipedes have severalpoints of leg contact, or virtual wave-springs,on the ground generating force at any giventime. Therefore, we modeled centipedewhole-body locomotor dynamics as the sumof several virtual wave-springs. The periodof each virtual wave-spring and the lag be-tween successive virtual wave-springs werealtered to model different kinematic condi-tions. Our model predicts that only underunobserved kinematic conditions would cen-tipedes demonstrate whole-body dynamicsof a rolling wheel, as predicted by Gray(1953), or have whole-body GRF and MEpatterns that complete a full cycle in atypicallyñdefined stride period. The modelpredicts that under most conditions, thewhole-body GRF and ME patterns will com-plete a full cycle in the period it takes for awave of legs to complete its contact with theground and the next wave of legs to be seton the ground. The period of time a wave ofcentipede legs is on the ground is analo-gous to the stride period in symmetrical gaits.

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P2.48ANDERSON, C.W., Idaho State Uni-versity, Pocatello, ID. Anatomical evidencefor brainstem circuits mediating hypoglos-sal motor output in the leopard frog, Ranapipiens.

Using injections of fluorescein dextranamine (FDA) combined with activity-depen-dent uptake of sulforhodamine 101 (SR101),brainstem circuits presumed to be involvedin hypoglossal motor output were investi-gated. Injections into the cerebellar cortexcombined with retrograde labeling of the pe-ripheral hypoglossal nerve demonstrateconvergence at the level of the medial re-ticular formation. This convergence suggestsan integrative region for afferent feedbackfrom the hypoglossal nerve and informationthrough the Purkinje cell layer of the cer-ebellar cortex. Injections of FDA into the cer-ebellar nuclei also demonstrate a bilateralefferent projection to the hypoglossal motorneurons. The SR101 data suggest a recip-rocal pathway between the medulla and thetrigeminal nuclei. This pathway was identi-fied through peripheral hypoglossal stimu-lation while SR101 was bath applied to asemi-intact brainstem preparation. Addition-ally, the SR101 uptake clearly labeled theventrolateral hypoglossal nuclei, the medialreticular formation and the Purkinje cell layerof the cerebellar cortex. The trigeminal nu-clei coordinate the motor output of the leva-tor mandibulae complex, the mouth closingmuscles, and this pathway may provide amechanism for coordinating tongue move-ments (through hypoglossal nuclei) with jawmovements during feeding. Taken together,these data provide additional insight for un-derstanding the neurophysiological path-ways used to coordinate the proper timingof feeding motor output in anurans.

1.3 ANDERSON, E.J.*, MCGILLIS, W.R.,GROSENBAUGH, M.A., Woods HoleOceanographic Institution. Boundary layerflow in fish and squid.

A complete hydrodynamic understand-ing of aquatic locomotion requires knowl-edge of the thin boundary layer surroundingswimming organisms. In particular, tangen-tial forces acting on the body surface aredependent on the distribution of velocity

throughout the boundary layer. Fluid veloci-ties tangent and normal to the bodies of swim-ming fish and squid were determinedthroughout the boundary layer (1-10mmthick) by digital particle image velocimetry(DPIV) and digital particle trackingvelocimetry (DPTV). Scup (Stenotomuschrysops), smooth dogfish (Mustelus canis),mottled sculpin (Cottus bairdi) and long-finned squid (Loligo pealei) were observed.The friction drag on swimming fish was de-termined to be greater than the rigid bodyfriction drag. No separation of flow was ob-served and the shape of boundary layervelocity profiles suggested that the fish weresensing and responding to the surroundingfluid to prevent separation. Both laminar andturbulent flow were observed in the bound-ary layer under various conditions, and flowsometimes oscillated between the two stateswith body phase. The behavior of the bound-ary layers of the carangiform swimming scupand the anguilliform swimming smooth dog-fish showed marked differences. Boundarylayer flow in mottled sculpin, which spendmost of their time stationary on the substrate,was shown to be greatly impacted by theorientation of the pectoral fins. The findingssupport the existence of different sensoryfunctions in the lateral line system anteriorand posterior to the pectoral fins as sug-gested by structural differences. In L. pealei,the boundary layer yielded estimates of fric-tion drag, and the effect of boundary layersuction at the mantle intake was observed.

5.6 ANDERSON, F.E.*, FOSTER, P.G.,Southern Illinois University, IL, The NaturalHistory Museum, London. Tests ofecdysozoan monophyly using molecular se-quence data.

Some analyses of 18S ribosomal RNAsequence data have supported monophylyof Ecdysozoa, a superphylum composed oftaxa that possess periodically molted chiti-nous cuticles (e.g., Arthropoda,Onychophora, Priapula and Nematoda). TheEcdysozoa hypothesis already has beenaccepted by many researchers, and this hy-pothesis (particularly the proposed close re-lationship between nematodes andarthropods) has been used to understand

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enigmatic developmental and genetic pat-terns within Nematoda. Recently, however,evidence from multiple nuclear protein-cod-ing genes has been presented suggestingthat Ecdysozoa (or at least a Nematoda +Arthropoda clade) is not monophyletic. Toevaluate support for ecdysozoan mono-phyly, we added nematode sequences topreviously published alignments for the 18Sgene and several nuclear protein-codinggenes and reanalyzed the data using maxi-mum parsimony and maximum likelihood(including heterogeneous ML models, inwhich model parameters such as base com-position can be estimated separately forparticular branches). We also analyzedalignments of two other genes (the nuclearelongation factor-1 alpha gene and the mi-tochondrial cytochrome c oxidase subunit Igene). Finally, we used a taxon jackknifingapproach with the 18S, EF-1 alpha and COIalignments to assess the role of taxon sam-pling in estimating ecdysozoan relationships.Our findings suggest that support forEcdysozoa across multiple data sets andtaxon samples is not unambiguous, and weargue that the use of the Ecdysozoa hypoth-esis for inferring character evolution withinNematoda may be premature.

S11.4ANDERSON, J.M.*, CHHABRA, N.K.,Charles Stark Draper Laboratory. Maneuver-ing and stability performance of a robotictuna.

The Draper Laboratory Vorticity ControlUnmanned Undersea Vehicle (VCUUV) isthe first mission-scale, autonomous under-water vehicle which uses vorticity controlpropulsion and maneuvering. Built as a re-search platform with which to study the en-ergetics and maneuvering performance offish-swimming propulsion, the VCUUV is aself-contained free swimming research ve-hicle which follows the morphology and ki-nematics of a yellowfin tuna. The forwardhalf of the vehicle is comprised of a rigid hullwhich houses batteries, electronics, ballastand hydraulic power unit. The aft section isa freely flooded articulated robot tail with isterminated with a lunate caudal fin. Utilizingoptimized body and tail kinematics from theMIT Robotuna experiments, the VCUUV hasdemonstrated stable steady swimming up

to 2.4 knots and aggressive maneuveringtrajectories with turning rates up to 75 de-grees per second. This paper summarizesthe vehicle maneuvering and stability per-formance observed in field trials and com-pares the results to predicted performanceusing theoretical and empirical techniques.

P3.48ANDREWS, A.L.*, HATLE, J.D.,CROWLEY, M.C., JULIANO, S.A., IllinoisState University Hemolymph protein pro-files during egg production in three popula-tions of the Eastern lubber grasshopper.

Distant populations of a given organismcan be predicted to have reproductive physi-ologies that are adapted to their local envi-ronment. For example, to avoid a reproduc-tive output of zero, populations of univoltinespecies from locations with shorter growingseasons could be predicted to reproducesooner than populations from locations withlonger growing seasons. In particular, a tran-sition from a developmentally flexible phaseto a developmentally inflexible phase (thatrequires a set amount of time) could be ex-pected to occur sooner in populations fromshorter growing seasons. Lubber grasshop-pers are univoltine and exhibit low vagility.In addition, they have flexible reproductivetiming during the first half of the ovipositioncycle but initiate inflexible reproductive tim-ing during the second half of the ovipositioncycle. The maximum titer of total hemolymphprotein (=TPmax) in lubbers occurs during thisinflexible phase. Here, we test whether lati-tudinally distinct populations of lubbers dif-fer in their timing of reproductive develop-ment, as indicated by the timing of TPmax. Wepredicted that the time from adult eclosion toTPmax (i.e. the flexible phase) would be great-est in Florida, intermediate in Louisiana, andlowest in Georgia lubbers. Contrary to pre-diction, times from eclosion to TPmax did notdiffer among the populations. Time fromTPmax to oviposition (i.e. the inflexible phase),however, was significantly greater for LAhoppers than GA hoppers. Our data sug-gest that the duration of the canalized phasediffers among populations and raises thepossibility that these differences may beadaptive for reproduction in the correspond-ing local environments. (Supported by NSFgrant DB1-9978810 to SAJ.)

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10.1 ANGILLETTA, M.J.*, LEE, V., SILVA,A.C., University of Pennsylvania, Philadel-phia. How do embryos incubated at highertemperatures spend less energy during in-cubation?

In some reptiles, the energetic cost ofdevelopment remains the same or evendecreases with increased incubation tem-perature. The surprisingly low energy expen-diture of embryos at high incubation tem-peratures may be caused by either of twomechanisms: 1) a shorter incubation peri-ods coupled with a relatively low thermalsensitivity of metabolic rate, or 2) acclima-tion of metabolic rate to incubation tempera-ture. In the eastern fence lizard, Sceloporusundulatus, incubation period is shortenedby 50% when incubation temperature is in-creased by 10 C. Consequently, embryosmust have a Q10 of 2.0 or lower to stabilizethe energetic cost of development . Other-wise, thermal acclimation of metabolic ratemust occur during development. We quanti-fied the thermal sensitivity of embryonic me-tabolism in S. undulatus with repeated mea-sures of metabolic rate at 27, 31, and 34 C.Similar to adult reptiles, metabolic rate ofembryos increased significantly with in-creased body temperature, from 1.5 J h-1 at27 C to 2.2 J h-1 at 34 C. The Q10 of metabolicrate from 27 to 31 C was only 1.6, which ismuch lower than Q10s of 2.0 to 3.0 that havebeen observed in adults. However, the Q10

of metabolic rate from 31 to 34 C was 2.7.Therefore, thermal acclimation must play arole in reducing the energetic cost of devel-opment at incubation temperatures that arehigher than 31 C. We found that embryosdid acclimate to incubation temperature; em-bryos incubated at 32 C had a lower meta-bolic rate than embryos incubated at 28 C,when both were measured at 30 C. Both thelow thermal sensitivity and thermal acclima-tion of metabolic rate play a role in stabiliz-ing the energetic cost of development in S.undulatus.

P2.59ARDELEAN, A.*, FAUTIN, D.G.,HUNSINGER, K., University of Kansas,Lawrence. Managing taxonomic synonyms.

Multiple names that refer to a single spe-cies (synonyms) and more than one spe-

cies being referred to by the same name(homonyms) bedevil taxonomy. They pro-duce ambiguity about the entity under dis-cussion. We demonstrate an electronic ap-plication that helps organize informationabout synonyms and homonyms. Outputfrom it can be used to generate synonymlists for taxonomic monographs. We illus-trate its utility in testing taxonomic and bio-geographic hypotheses. This research wassupported by NSF grants DEB-9521819and DEB-9978106 to DGF (in the programPartnerships to Enhance Expertise in Tax-onomy), and OCE-0003970 to DGF and R.W. Buddemeier (in the National Ocean Part-nership Program).

S7.11ARP, A.J., Romberg Tiburon Center forEnvironmental Studies. The ecology andphysiology of the marine echiuran worm,Urechis caupo: a model animal for demon-stration of physiological principles.

Urechis caupo is a large echiuranworm endemic to the California coast. Popu-lations of these worms inhabit individual, wellventilated, U-shaped burrows in the marinemudflat. Urechis is a non-selective filterfeeder which uses an intricate mucus net totrap its particulate food. Although enrichedin organic material, the mudflat habitat issubject to periodic exposure to toxic sulfideand hypoxia during low tide events. Overthe last 14 years our laboratory group hasinvestigated the ecophysiology of this ani-mal — including the ecology, behavior, mor-phology, physiology, metabolism, and cellu-lar biochemistry that allow it to flourish in thechallenging mudflat environment. One over-riding observation has emerged: this uniqueechiuran worm demonstrates numerousspecialized adaptations that provide an ex-cellent demonstration of a variety of physi-ological principles. This presentation will at-tempt to synthesize all we have learned fromecological and physiological studies, start-ing with Fisher and MacGinitie 1928, into anoverview of the natural history and biologyof this unusual animal, and will highlight theusefulness of Urechis as a model in theteaching and research laboratory.

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P3.91ASAY, M.J.*, BOYD, S.K., University ofNotre Dame. Distribution of arginine vasoto-cin in the brain of a non-vocalizing anuran(Ascaphus truei).

Tailed frogs (Ascaphus truei) are endemicto the Pacific Northwest and are consideredthe most primitive extant anuran. In addi-tion, unlike most anurans, they do not vocal-ize. Arginine vasotocin (AVT) is a neuropep-tide that modulates many amphibian repro-ductive behaviors, including mating calls.The distribution of AVT-immunoreactive(AVT-ir) cells in the brain of Ascaphus couldprovide insight into AVT control of behaviorin amphibians. We used immunocytochem-istry and a rabbit polyclonal antibody raisedagainst vasopressin to detect putative AVT-ir cells and fibers in brains from adult maleand female Ascaphus. The overall distribu-tion of immunoreactivity was more restrictedin Ascaphus than previously reported forother anurans. Significant populations ofAVT-ir cells were found in the magnocellularpreoptic nucleus and suprachiasmaticnucleus in the diencephalon. A muchsmaller population of cells was found span-ning the dorsal and ventral striatum. AVT-irfibers were found in some areas that controlvocal behavior in other anurans. AVT maythus have alternative functions in these ar-eas in Ascaphus. Supported by NSF IBN95-14305.

S6.1 ASHLEY-ROSS, M.A.*, GILLIS, G.B.,Wake Forest University, Harvard University.A brief history of functional morphology.

The discipline of functional morphologygrew out of a descriptive comparative ana-tomical tradition; its transformation into amodern experimental science facilitatedlargely by technological advances. Earlymorphologists, such as Cuvier and Thomp-son, felt that function was predictable fromorganismal form, to the extent that animalsand plants represented perfect adaptationsto their habits. However, anatomy alonecould not inform morphologists how organ-isms actually performed their activities. Re-cording techniques capable of capturing fastmotion were first required to begin to under-stand animal movement. Muybridge is per-haps most famous for his pioneering work in

fast photography, enabling him to “freeze”images of even the fastest horse at a fullgallop. In fact, what functional morphologistsnow practice as kinematic analysis grew di-rectly out of the techniques Muybridge de-veloped. Marey, though lesser known thanMuybridge, made perhaps an even greatercontribution to experimental science throughhis invention of automatic apparati for re-cording events of animal motion. Thus func-tional morphologists could begin to makereasonable predictions of how the muscu-loskeletal system generated movement, aswell as provide the structural foundations ofform. In the middle of the 20th century, scien-tists discovered a way to record what themuscles of an awake, behaving animal weredoing. The technique of electromyography,initially used extensively, in clinical applica-tions, was co-opted as a tool of comparativefunctional anatomy by researchers such asGans and colleagues. High-speed kinematicanalysis and electromyography have formany years been the mainstay of experi-mental technique in functional morphology.In recent years, functional morphology hasbegun to branch out to incorporate ap-proaches from other disciplines, and nowstands at the threshold of becoming a trulyintegrative, central field in organismal biol-ogy.

P2.1 ASHRAF, M., NESBITT, R.A., LEE,C.M.*, Howard University, Washington, DC.Positioning of kinetoplasts in Trypanosomamusculi and Typanosoma lewisi during thedevelopment in-vitro.

Trypanosoma musculi is parasitic to miceand Trypanosoma lewisi is parasitic to rats,and both of these parasites are highly spe-cific to their hosts. The development of Try-panosoma musculi and Trypanosoma lewisiwere studied in vitro in the presence of ad-herent splenic cells. Both parasites devel-oped only when attached by their flagellartips to splenic adherent splenic cells. Dur-ing the proliferation of T. musculi, the kineto-plast migrated towards the nucleus, andonce in the vicinity of the nucleus, the nucleardivision was triggered. Trypanosoma mus-culi divided as epimastigotes. The kinetoplastof T. lewisi did not migrate towards the

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nucleus but remained at its original location.The nucleus and kinetoplast divided at thesame time. Both parasites started dividingfrom their flagellar ends and T. musculi and T.lewisi daughter cells were formed within 48hour. Trypanosoma lewisi did not form ro-sette-like pattern around the adherent cellsand remained as trypomastigote forms. It isalso observed that after 48 hour in culture, T.lewisi were able to divide without attachingto the adherent cells. However, the unavail-ability of the adherent splenic cells in vitroled the parasites to transform into round non-viable forms.

4.2 AZIZI, E.*, LANDBERG, T.,BRAINERD, E.L., University of Massachu-setts, Amherst. Kinematics and performanceof the escape response in an aquatic sala-mander, Eurycea bislineata.

Despite the large body of information onthe aquatic escape response of fishes, thekinematics and neurobiology of fast-startsin salamanders remain poorly understood.We examine the effect of ontogeneticchanges in morphology on escape perfor-mance in larval and adult two-lined sala-manders, Eurycea bislineata. The two lifestages of this lungless stream salamanderoverlap in body size. Body length in oursample ranged from 4.8 to 6.4 cm in larvaeand 5.8 to 7.5 cm in adults. At metamorpho-sis, these salamanders lose the tail fin whichreduces the lateral profile in the caudal re-gion of the adults. Analysis of cross-sec-tions at various body positions reveals a de-crease in the relative muscle mass of adults.We elicited escape responses using tactilestimuli directed at the forelimbs of E.bislineata. The observed kinematics, whichconsist of a preparatory and a propulsivephase, resemble the C-starts described fornumerous fish species. The duration of stage1 (C-forming phase) was found to increasewith body length. Maximum body curvature(measured at the end of stage 1) varied be-tween larval and adult salamanders. Be-cause differences in relative muscle massand lateral profile have been shown to ef-fect escape performance in fish, we hypoth-esize that the observed morphological and

kinematic variation in larval and adult E.bislineata will lead to differences in escapeperformance.

P1.38BACHMAN,G.C., University ofNebraska,Lincoln. Changes in leukocytecounts in hibernators from spring throughsummer.

At high elevations, hibernators such asBelding’s ground squirrels (Spermophilusbeldingi) emerge through snow and are un-able to forage for the first few weeks of spring.Potentially, these individuals face a trade-offbetween allocating limited energy and nu-trients to re-establishing physiological func-tion, and the need to fuel activity associatedwith the brief breeding period which alsooccurs at this time. Immune function appearsto be among the systems that show somedegree of regeneration after emergence.Blood smears were collected periodicallyfrom squirrels from May (days after emer-gence) through August allowing me to fol-low changes in individual profiles over time.Two measures were taken from these slides- a differential leukocyte count and a mea-sure of the relative number of leukocytesrelative to erythrocytes. The analyses focuson the populations of immature and matureneutrophils, lymphocytes, and immature leu-kocytes as other cell types were rare. Thetime series indicate a progressive matura-tion of the leukocyte population and an in-crease in the relative number of leukocytes.Associations between leukocyte counts andindividual behavior and body compositionwill also be presented.

P1.89BAGATTO, B.*, WOLOSZYN, L.,BURGGREN, W., University of North Texas.3-D visual assessment of cardiovscular func-tion in zebrafish larvae.

Numerous investigators are now mea-suring stroke volume of developing verte-brates by optical examination. The standardmethod for many animals, including zebrafishlarvae, involves fixing the larvae, and cap-turing two dimensional video of lateral viewsof the beating heart through an inverted mi-croscope. To arrive at a volume, the zebrafishheart is assumed to be in the shape a pro-late spheroid. However, during early larval

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development, the zebrafish heart is shapedmore like a tube, which begins to S-fold as itdevelops into its final shape. To assess strokevolume, and then, calculate cardiac outputin these young larvae, a third dimensionalmeasurement is needed. Our technique in-volves securing the living, intact larva, in alow temperature melting point agarose cyl-inder. The larva is then rotated through a full180 degrees beginning at one lateral view,through the ventral view, to the other lateralview. The resulting three dimensional rep-resentation of the developing heart as itbeats allows for more accurate calculationof diastolic and systolic volume, and hencestroke volume and cardiac output. In addi-tion, this technique allows us to quantify theformation and three dimensional shape ofvessels during early development. (sup-ported by NSF IBN 98-96388).

P1.93BAIER, D.B.*, GATESY, S., Brown Uni-versity. The role of avian slow-twitch fibers inturkey tail display.

EMGs from the tail muscles of male tur-keys (Meleagris gallopavo) vary in ampli-tude between flight and display. In flight, cau-dal tail muscles yield high amplitude EMGstypical of twitch fibers. In display, male tur-keys fan, raise, and turn their tails with littleor no EMG activity. Slow-tonic muscle fibers(type III) like those found in the avian M. latis-simus dorsi cranialis were hypothesized tobe responsible for display postures, whichcan be maintained for several hours. Suchtonic fibers do not propagate action poten-tials thereby explaining lack of conspicuousEMG signals. Histochemical staining formATPase was used to characterize tailmuscle fiber types. The primary muscles in-volved in raising the tail (M. levator caudaepars vertebralis, M. levator caudae parsrectricalis) and in fanning (M. bulbirectricium) all show mixed populations ofslow-twitch (type I) and fast-twitch (type II)fibers. The muscle previously assumed toturn the tail (M. lateralis caudae) containsonly fast-twitch (type II) fibers. No slow-tonic(type III) fibers have been identified in anycaudal muscle. However, avian slow-twitchfibers are also multiply innervated, unlikemammalian slow-twitch fibers. Despite their

innervation, avian slow-twitch fibers are of-ten considered to be action potential-propogating. Our histochemical results, to-gether with EMG activities, suggest that avianslow-twitch fibers are responsible formaintaing tail posture during display.

P3.33BAKER, P.J., Miami University. Onto-genetic changes in plastral callosities of theSenegal flapshell turtle, Cyclanorbissenegalensis.

The number and location of the plastralcallosities are reliable characters used todistinguish adults of the Senegal flap-shelledturtle, Cyclanorbis senegalensis, from itscongener the Nubian flap-shelled turtle, C.elegans. Adult C. senegalensis have sevento nine callosities present on the plastronincluding five preplastral callosities whereasadult C. elegans have a maximum of fourcallosities with no preplastral callosities.However, difficulties in identification arisewhen comparing specimens of different sizesand sexes. After examining a large series oflive C. senegalensis, with specimens rang-ing from juvenile to adult, I have observedthat the development of the plastral callosi-ties is determined by both the size and sexof the individual. Females attain a greatercarapace length (CL) than males; and thusmales develop a full complement of ninecallosities at a smaller CL than females. Thenumber, size, and shape of the plastral cal-losities of C. senegalensis can be used asboth a character to distinguish male fromfemale specimens, as well as a diagnosticcharacter to distinguish between species.

P1.79BAKKEN, G.S.*, WILLIAMS, J.B., Indi-ana State University, Terre Haute, Ohio StateUniversity, Columbus. Effect of wind andgrowth on the thermoregulatory metabolismof Arctic-breeding shorebird chicks

Many Arctic-breeding shorebird chicksleave the nest and forage with one or bothparents soon after hatching. Chicks may beexposed to temperatures near 0oC, and tun-dra habitats offer little shelter from wind.Parental attentiveness prevents severe hy-pothermia, but foraging time may be limitedby thermoregulatory competence. We usedopen-circuit respirometry to measure the

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oxygen consumption and evaporative wa-ter loss rates of downy chicks of 3 species ofArctic-breeding shorebirds, the least sand-piper, (Calidris minutilla), short-billed dow-itcher (Limnodromus griseus), and whimbrel(Numenius phaeopus). Chicks ranged from9 to 107g in mass and were generally 85 to350 hours old during measurements. Mea-surements were made at wind speeds of 0.1,0.8, 1.8 and 3.0 m/s. Air temperatures rangedfrom 15 to 30oC, depending on age and spe-cies, and were selected so that standard op-erative temperatures always fell somewhatbelow the lower critical temperature. Whilechicks can withstand temperatures below10oC for short periods with no wind, theyfrequently became hypothermic during ex-tended (2 hour) measurements below 20oCwith wind. Normothermic body temperaturesduring measurements averaged 39 ±1oC fordowitchers and whimbrels. Sandpiper bodytemperature increased with age from 37 oCat 170 hours to 39 oC at 220 hours. As windu increased from 0.1 to 3 m/s, mass-specificthermal conductance, K (W/g-oC) increased62% for sandpipers, 42% for dowitchers,and 35% for whimbrels. The combined ef-fects of mass and wind are approximated bylog(K) = -2.1 -0.54 log(m) + 0.055u.

S11.3BANDYOPADHYAY, P.R., Naval Un-dersea Warfare Center, Newport, RI. Maneu-vering hydrodynamics of fish and small un-derwater vehicles

The understanding of fish maneuveringand its application to underwater rigid bod-ies are considered. The goal is to gain in-sight into stealth. The recent progress madein NUWC is reviewed. Fish morphology sug-gests that control fins for good maneuver-ability have unique scalar relationships irre-spective of their speed type. Maneuveringexperiments are carried out with fish that arefast yet maneuverable. The gap in maneu-verability between fish and small underwa-ter vehicles is quantified. The hydrodynam-ics of a dorsal fin based brisk maneuveringdevice and a dual flapping foil device, asapplied to rigid cylindrical bodies, are de-scribed. The role of pectoral wings in ma-neuvering and station keeping near surfacewaves is discussed. A pendulum model of

dolphin swimming is presented to show thatbody length and tail flapping frequency arerelated. The mechanism of discrete and de-terministic vortex shedding from the oscillat-ing control surfaces has the property of largeamplitude unsteady forcing and an exquis-ite phase dependence, which makes it in-herently amenable to active control for pre-cision maneuvering. Theoretical control stud-ies demonstrate the feasibility of maneuver-ability of biologically-inspired bodies undersurface waves. The application of fish hy-drodynamics to the silencing of propulsorsis considered. Two strategies for the reduc-tion of radiated noise are developed. Theeffects of a reduction of RPM are modeled.The active cambering of blades made of digi-tally programmable artificial muscles, andtheir thrust enhancement, are demonstrated.Next, wake momentum filling is carried outby artificial muscles at the trailing edge of astator blade of an upstream stator propulsor,and articulating them like a fish tail. A reduc-tion of blade tonals is demonstrated theo-retically.

P3.44BARAGONA, M.A.*, HAIG-LADEWIG,L.A., WANG, S.Y., University of Southern Mis-sissippi, Hattiesburg. Multiple paternity in thegrass shrimp Palaemonetes pugio.

Microsatellite markers were used to studythe mating system of Palaemonetes pugio.Grass shrimp genomic libraries werescreened for clones containing di- or trinucle-otide repeats. Positive clones were se-quenced and PCR primers were designedfor clones containing more than five tandemtrinucleotide repeats or more than seven tan-dem dinucleotide repeats. Among the 11microsatellite loci characterized, two wereselected on the basis of polymorphism andease of amplification to genotype 30 em-bryos from each of 10 brooding females col-lected from an estuary in the northern Gulf ofMexico. Results indicate that 8 of the 10 fe-males were brooding embryos sired by morethan one male.

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58.5 BARKER, J.U., ASHLEY-ROSS, M.A.*,Wake Forest University. The effect of fibertype heterogeneity on work and power out-put of hindlimb muscles of the tiger sala-mander.

Most vertebrate muscles are composedof a mixture of fiber types. However, study ofthe mechanical performance of muscle hasconcentrated on homogeneous bundles ofmuscle fibers. Muscles in the hindlimb of thetiger salamander, Ambystoma tigrinum,present an excellent opportunity to explorethe consequences of fiber heterogeneity onwork and power output. Isometric twitchesand work loops were performed in vitro ontwo muscles, the M. iliotibialis pars posterior(ILTP; heterogeneous, containing SO, FOGand FG fibers) and the M. iliofibularis (ILFB;homogeneous, containing FOG fibers only).Maximal isometric twitch force in the ILTPwas over twice as great as in the ILFB; how-ever, when adjusted for cross-sectional area,mean isometric stress was statistically in-distinguishable (ILTP: 46.2 +/- 21.4 kN/m2;ILFB: 40.1 +/- 21.5 kN/m2). Work loops wereperformed over a range of frequencies (0.5ñ 3.0 Hz) that encompassed the observedrange of in vivo limb cycling frequencies. Thehomogeneous ILFB showed a steady de-cline in work per cycle from 1.5 ñ 3.0 Hz,while power output over those frequenciesremained nearly constant. The heteroge-neous ILTP showed a different pattern, witha tri-modal distribution for work per cycle withpeaks at 0.5, 1.5, and 2.5 Hz, and maximalpower output at 2.5 Hz. The differences inmechanical performance between the ILTPand ILFB may relate to the musclesí functionduring locomotion. The ILFB is active at thebeginning of the swing phase, and serves tolift the hindlimb from the ground. Steadypower output may be required for this ballis-tic-like movement, as the weight of the limbis unchanging. In contrast, the ILTP functionsto extend the knee, and thus can contributeto forward propulsion. High power output athigh cycling frequencies may indicate theILTP assists fast locomotion.

P3.11 BARRIGA-SOSA, I.*, ARRE-DONDO-FIGUEROW, J. L., UniversidadAutonÛma Metropolitana Unidad Iztapala.Morphological and allozyme variation inChirostoma grandocule Steindachner (Pi-sces: Atherinopsidae) from Lake P·tzcuaro,Mèxico.

We investigated the levels of populationdifferentiation of the silverside fish speciesChirostoma grandocule Steindachner inLake P·tzcuaro based on morphometric andallozyme data and relate such informationto aspects of life history and changes in theirnatural habitat. We analysed eighteen mor-phometric characters, eight meristic andeleven putative enzyme-coding loci from C.grandocule samples of two different locali-ties ("subpopulations") within the lake andof three different years (Janitzio 1996, 1999and Ichupio 1997). Principal Component(PC) analysis with the morphometric dataindicate the separation of two groups(grouped into four components, 66.78%).Among the variables that contributed thehighest variation were: pelvic fin length ofbase (PfbL), head length (HL), eye diameter(ED), dorsal 2nd lengh (D2L) and snoutlength (SnL). Discriminant analysis (DA) withmorphometric data also indicated separa-tion between samples (87.10% correctly clas-sified) Janitzio and Ichupio (Wilk's l= 0.13-48, P< 0.000). Allozyme data resolved sevenpolymorphic loci at P.99 level. C. grandoculeshowed levels of He that ranged from 0.0134to 0.0319 (average HS = 0.0234). Geneticdifferences were observed between yearsand between "subpopulations", with six al-leles of Janitzio never detected in Ichupioand one of Ichupio not present in both yearsof Janitzio samples. Genetic distances (DR& co-ancestry) between samples rangedfrom 0.0154 to 0.0341. Weir & Cockerham'sF-statistics provided evidence of significantheterogeneity among "subpopulations" andyears (jack-knifed qS = 0.0252, S.D. 0.0126).Our morphometric and allozyme results areconsistent and suggest that Chirostomagrandocule is encountering an actual pro-cess of population differentiation in lakeP·tzcuaro.

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1.4 BARTOL, I.K.*, GORDON, M.S., Uni-versity of California, Los Angeles. Flow pat-terns around boxfishes: role of body keels indynamic stability.

The tropical marine boxfishes and theirrelatives (family Ostraciidae) are some of themost highly specialized living bony fishes.The forward 2/3 to 3/4 of their bodies arecovered by rigid bony tests, which restrictbody movements to their fins and the poste-rior sections of their tails. Recent field andlaboratory observations indicate that thesefishes demonstrate great maneuverability,dynamic stability, and course control. Thediversity in body architecture and keel char-acteristics among the ostraciids makes itpossible to determine the roles of the bonytests in maintaining stability. Various featuresof the tests of four morphologically distinctostraciids were measured to develop a bet-ter understanding of body variation in thisgroup. Flow patterns in the wakes and alongthe bodies of stereolithographic models ofostraciid fishes positioned at various anglesof attack in a water tunnel were measuredusing digital particle image velocimetry(DPIV) to determine how test morphologyimpacts flow and ultimately dynamic stabil-ity. Significant differences in test character-istics, such as relative location of maximumtest height/width, number and angle of keels,and degree of lateral/ventral body curvature,were detected among the four ostraciids.These differences impacted flow patternsaround the models. At angles of attackgreater than 5 degrees or less than -5 de-grees, vorticies developed most prominentlyaround sharp, ventral, posterior keels withadjacent concave channeling. These vorti-ces, which occurred posterior to the centerof mass and produced upward directedforces at positive angles of attack and down-ward directed forces at negative angles ofattack, presumably provide self-correctingforces that aid rigid-bodied swimmers in pitchcontrol. Supported by ONR grant N00014-96-0607.

S9.2 BARTON, B.A., University of SouthDakota. Stress in fishes: a diversity of re-sponses.

Fishes display a wide diversity in theirphysiological responses to stress. Primary

endocrine responses to acute stress includethe release of catecholamine and corticos-teroid hormones into circulation. Corticos-teroids, chiefly cortisol, are released by theinterrenal tissue, the adrenal homologue infish, which is concentrated in the anteriorportion of the kidney in teleostean fishes butfound more diffusely scattered throughoutthe kidney in chondrosteans. Elevations incirculating cortisol during the first hour afteran acute disturbance can increase from rela-tively low resting levels to between about 20and >1,000 ng/mL, depending on species.Basal teleost groups, such as salmonids,generally exhibit lower responses than de-rived species, such as the percids, althoughenvironmental and developmental factorsstrongly influence the stress response in fish.Some of these factors include temperature,nutritional state, water quality, and prior ex-posure to stressors. Chondrosteans, spe-cifically scaphirhynchid sturgeons andpaddlefish, show post-stress cortisol eleva-tions to <10 ng/mL following a similar acutestressor, which is much lower than those inteleosts. These differences in primary re-sponses appear to be reflected in their sec-ondary physiological responses to stress,such as changes in plasma glucose, lactateand chloride, which also appear to be muchlower in chondrosteans than in teleosts.Brain serotonergic activity, which has beenimplicated in regulation of the hypothalamic-pituitary-interrenal axis during stress, alsoappears to be appreciably lower inchondrostean fishes than in teleosts. To date,little comparative work has been done inelasmobranch fishes, which release 1AL-PHA-hydroxycorticosterone as the principlecorticosteroid.

P1.37BAUMANN, N.L.*, LIGHT, D.B., RiponCollege. Purinergic receptor activation leadsto a calcium-sensitive volume decrease inmudpuppy erythrocytes.

Regulatory volume decrease (RVD) inmudpuppy (Necturus maculosus) erythro-cytes has been shown to depend on ATP-,Ca2+-, and phospholipase A2 (PLA2)-depen-dent pathways (Light et al. 1997. J. Membr.Biol. 158: 229). This study was designed todetermine the relationship between these

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agents during RVD. The hemolytic index (HI)decreased with extracellular ATP (50MICROmolar) and the Ca2+ ionophoreA23187 (0.5 MICROmolar). In contrast, HIincreased with the purinoceptor antagonistsuramin (100 MICROmolar) and the PLA2

inhibitor ONO-OS-082 (10 MICROmolar). In-terestingly, A23187 (0.5 MICROmolar) re-versed the inhibitory effect of suramin (100MICROmolar), indicating the Ca2+-depen-dent step was downstream of a P2 receptor.Extracellular ATP (50 MICROmolar) did notreverse the antagonistic affect of ONO-OS-082 (10 MICROmolar), suggesting that P2receptor activation occurred prior to produc-tion of arachidonic acid. The percent volumerecovery of cells following hypotonic shock(0.5X Ringer), measured with a Coultercounter, increased with extracellular ATP (50MICROmolar) and A23187 (0.5MICROmolar). In contrast, suramin (100MICROmolar) inhibited volume recovery; thisinhibition was reversed with A23187 (0.5MICROmolar). Finally, using the whole-cellpatch clamp technique, we found ATP (50MICROmolar) enhanced a K+-conductancethat was activated during cell swelling. Thiscurrent was inhibited by ONO-RS-082 (10MICROmolar) and suramin (100MICROmolar). Conclusion: our results aremost consistent with extracellular ATP acti-vation of a P2 receptor occurring prior to arise in intracellular Ca2+. This, in turn, acti-vates PLA2 and subsequent K+ efflux througha conductive pathway. (Supported by NSFgrants MCB-9603568 and MCB-0076006.)

P2.58BEACHUM, C.*, STRANGE, R.,Southeast Missouri State University. Anevaluation of phylogeny inference programsand packages.

Phylogenetic inferences from large datasets can be problematic, with conflict be-tween precision and minimal computer timedetermining the design of computer pack-ages. We analyzed two large DNA datasets obtained from GenBank and a smallerhomoplasy-rich morphological data set todemonstrate inconsistencies among threephylogeny building packages (PHYLIP,HENNING86, and PAUP*4.0). The sequencedata was analyzed under the criterion of

maximum parsimony, maximum likelihood,neighbor joining, and bootstrap where ap-plicable. HENNING86 performed well as aparsimony engine, consistently finding theshortest tree in the least amount of time.However it is the oldest of the four pack-ages and is the only one not offered for Unix,Windows, and Mac operating systems.Random Cladistics is a free upgrade thatallows many different analyzing methods.PHYLIP3.5 is a free package that can per-form many different analyzing methods. Itis slow and retains an upward limit of only100 trees, regardless of the number ofequally parsimonious trees. Despite its prob-lems, PHYLIP is free, has the best onlinehelp, and is a well integrated package. Analpha version of PHYLIP3.6, released thisyear, is still slow. It is more plastic and hasadded an adjustable maximum number oftrees. PAUP*4.0 is the most refined of thefour programs. It has the greatest numberof available options. It is relatively quick andeasy to navigate in the point and click for-mat. However, the available options may bedaunting to novice users. PAUP* is the bestoverall package for serious researchers. Re-searchers and educators need to considertheir requirements before committing them-selves to specific programs.

P1.27BEAULIEU, L., ALLEN, S., BURNETT,K., BURNETT, L.*, College of Charleston,University of Charleston, SC, University ofCharleston, SC, University of Charleston,SC. Low ph effects on the killing activity ofoyster hemocytes.

An assay was used to measure the abil-ity of hemocytes of the Eastern oyster,Crassostrea virginica to kill the bacteriumVibrio parahaemolyticus. Experiments werecarried out at pH 7.6 and 6.6 mimicking thein vivo hemolymph environment within theoyster under well aerated conditions (7.6)and during air exposure (6.6). Assays werecarried out using 96-well plates to exposehemocytes to Vibrio (1:20 ratio) for 3 hoursat room temperature during which time thehemocytes phagocytized the Vibrio. The ph-agocytosis stage of the assay was termi-nated by adding 0.2% Tween to the wells,killing the hemocytes but not the Vibrio. A

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culture medium was then added to each welland the remaining Vibrio allowed to grow for2 hours. The number of live Vibrio in eachwell after the growout period was measuredusing a colorimetric cellproliferation assay.A killing index was calculated based on thenumber of Vibrio in wells with hemocytescompared to their control wells (i.e., withhemocytes killed at time zero). A killing in-dex of Vibrio was expressed as a percent-age of the control, e.g., where an index of50% indicates that 50% of the bacteria werekilled by hemocytes. The average killing in-dex at pH 7.7 was 49.2 (1.86 SEM; n=4) andlower, but not significantly different at pH 6.6,38.8 (1.80 SEM; n=4). Under these assayconditions hemocyte viability, as judged bytrypan blue exclusion, was high at the be-ginning of the assay (90.4-98% viable at pH7.6; 87.4-95% at pH 6.6) and remained highfor three hours (83.2-92% viable at pH 7.6;86-92% at pH 6.6). These results suggestthat low pH does not cause a significant re-duction in the killing activity of oysterhemocytes. Supported by NSF-REU DBI-9876926 & ODRP NA96RG0488.

P2.82BECK, A.L.*, BLOB, R.W., HOPSON,J.A., University of Chicago, IL, Field Museum,Chicago, IL, University of Chicago, IL. Mor-phological indicators of sprawling and non-sprawling limb posture in tetrapods.

Determination of locomotor postures infossil tetrapods is difficult because their be-havior cannot be observed directly. To evalu-ate morphological indicators of limb posturethat could be used to interpret stance in ex-tinct tetrapods, we have used multivariatestatistical analyses to explore osteologicalcorrelates of locomotor posture in extantspecies. Our sample of extant taxa includesgeneralized mammals, lizards, and croco-dilians spanning a large size range. Mor-phological measurements and observationsrelevant to locomotor function were takenfrom the forelimb, hindlimb and girdle skel-etons of museum specimens. Principal com-ponents analyses as well as bivariate com-parisons of limb and girdle elements indi-cate strong differences between sprawlingand non-sprawling taxa. For instance, highlysprawling taxa are characterized by limbs

with high angles of femoral torsion, shortmetatarsals, and reduced articular surfaceson the distal humerus. In contrast, non-sprawling taxa show significantly smallersurface areas than sprawling taxa for thehip, knee, and ankle joints. These analysessuggest several quantifiable morphologicalfeatures that could aid the evaluation of limbpostures in fossil taxa, thereby facilitating theevaluation of changes in limb posture overthe evolution of mammalian locomotion.

P2.15BECK, S.L., DePaul University. Skel-etal variation by “batch” among CD-1 micereveals continuing genetic heterogeneity.

The random-bred CD-1 mouse is widelyfavored as a test organism by regulatoryagencies, pharmaceutical houses, amongothers, because of their broad array of geno-types, mimicing the human population. Thereis, therefore, concern about their continu-ous genetic heterogeneity. We purchased 7groups of CD-1 mice from the same sup-plier, over a period of several years. Thepresent study compares untreated controlsfrom these 7 “batches”;, at 60-65 days postnatal, for 88 normally-occurring skeletal vari-ants. Most of the skeletal variants examinedeach strain-specific values among inbredstrains and so are a good indicator of varia-tion. There was significant (P<0.01) varia-tion between groups among 63 variants.Seventeen variants never appeared, and 9occurred in only 1 specimen in all 7 groups(686 mice). High variability among all groupswas seen for 10 variants. Average numberof variants for each group that differ in 2-way comparisons with each of the others,and ranges, are: G1 = 21 / 16-26, G2 = 18.2/ 16-23, G3 = 20 / 16-23, G4 = 16.7 / 10-26,G5 = 13.8 / 9-19, G6 = 16.5 / 9-25, G7 = 16.2/ 13-22. The variants showing the largestnumber of significant comparisons weredoubled Mandibular Foramen (18 of 21possible comparisons), doubled ForamenPterygoideus (15), imperfect TransverseForamen on cervical vertebra (CV) 7 (15),Arch Foramen CV5 (15), Parted Frontalbones (14), Malformed Sternebrae (14),anteriad suture on posterior border of thePalatine bone (14), perforated FossaOlecrani of the humerus (13), and

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caudalized Sacral Vertebra 3 (12). The size-able number of variants which differ signifi-cantly in these 7 groups of CD-1 mice pur-chased over a period of several years sug-gest that these animals continue to be mor-phologically diverse. (Supported by theDepartment of Biological Sciences and theUniversity Research Council of DePaul Uni-versity).

16.2 BECKMAN, B.R.*, FAIRGRIEVE, W.,COOPER, K.A., MAHNKEN, C.V.W.,DICKHOFF, W.W., Northwest Fisheries Sci-ence Center, National Marina. Endocrinecorrelates of growth in ocean dwelling cohosalmon.

Pacific Salmon typically spend 1-3 yearsforaging and growing in the ocean prior toreturning to freshwater spawning sites. In-ter-annual differences in ocean temperaturesand productivity may have profound effectson the growth of these animals. Growth varia-tion may influence age of maturation, size atmaturation, and overall year-class survival.Thus, understanding variation in oceanicgrowth rates is important to understandingvariation in the fitness of Pacific salmon.However, it is very difficult to measure oce-anic growth rates. Growth is mediated bythe endocrine system; consequently, endo-crine correlates of growth may provide a valu-able tool for assessing relative growth rateand related fitness values, based on a singleblood sample. We conducted an experimentrelating growth rate to plasma hormone lev-els in order to test this idea. Specifically, weindividually tagged approximately 1200yearling coho salmon, placed them in sea-water tanks and assessed growth at twomonth intervals. Plasma was obtained inSeptember and November and we found asignificant, highly correlated (r2>0.5) rela-tion between IGF-I and growth rate. Wefound little relation between insulin andgrowth. Subsequently, we obtained samplesfrom coho salmon in the Strait of Georgiaand Puget Sound (West Coast of NorthAmerica). IGF-I data obtained from thesesamples shows both geographic andinterannual variability. These preliminarydata suggest that a more extensive sam-pling regime (geographically and tempo-

rally) for IGF-I levels of Pacific salmon maygive us insight into environmental factorsregulating growth and fitness.

38.5 BEE, M.A.*, GERHARDT, H.C., Uni-versity of Missouri, Columbia. Getting to knowyou: habituation as a mechanism for territo-rial neighbor recognition.

Territorial animals commonly exhibit lowlevels of aggression toward familiar neigh-bors in their usual territories and high levelsof aggression toward strangers and neigh-bors in novel locations. Vocal recognition ofneighbors is well known in songbirds, andalso has been demonstrated in bullfrogs,Rana catesbeiana. Habituation has beensuggested as a learning mechanism forneighbor recognition. However, no study hastested the hypothesis that repeated expo-sures to a neighbor's acoustic signals allowterritorial animals to learn about individuallydistinct signal properties and the usual lo-cation of signal origin. We conducted 3 fieldplayback experiments using a habituation/discrimination procedure to test the hypoth-esis that habituation functions as a mecha-nism of neighbor recognition in bullfrogs.Synthetic bullfrog calls were broadcast toterritorial males during a habituation phaseuntil aggressive responses declined. Wethen presented novel stimuli during a sub-sequent discrimination phase. In experiment1, a change in fundamental frequency, anindividually distinct call property, elicited re-newed aggression. In experiment 2, a 180o

change in stimulus location elicited renewedaggression. In experiment 3, changes in fun-damental frequency, location, or both fre-quency and location elicited renewed ag-gression. Responses were highest tochanges in fundamental frequency, andthese responses were independent of loca-tion; responses to changes in location alonewere intermediate between responses tochanges in frequency and controls. Our dataindicate that repeated exposure to aneighbor's call resulted in stimulus-specificand location-specific response decrements,suggesting that habituation could functionas a mechanism for neighbor recognition inbullfrogs.

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5.3 BEGOVIC, E., University of California,Berkeley. Feeding specialization and diver-sification patterns of eastern PacificPatellogastropoda.

To investigate the role that feeding spe-cialization may play in clade diversificationand mode of speciation, I have begun pre-liminary phylogenetic and sterol analysesof Eastern Pacific Patellogastropoda. A phy-logenetic hypothesis for Eastern PacificPatellogastropoda is constructed usingmtDNA sequences from the large ribosomalsubunit (16s). This phylogeny identifies twoputative new species that have sympatricdistributions with their respective sister taxa.Both of these taxa share common resourcesand similar ecotypic forms with their closestsister taxa, indicating that resource partition-ing may not have played a significant role intheir diversification. This phylogeny alsoconfirms that L.austrodigitalis (Murphy, 1978)is the sibling species of L.digitalis, two spe-cies with parapatric distributions overlappingin central California and similar ecotypicforms. This pattern is consistent with the hy-pothesis that these species diversified as aresult of vicariance. Finally, 16s data indi-cate that L.instabilis and L.ochracea are twodistinct ecological forms of the same spe-cies. A re-evaluation of the systematics ofpatellogastropod species is needed. Prelimi-nary analyses have been used to identifybiogenic sterols in a subset of lottid taxa. Ste-rols incorporated into shell and body tissuescan be used to identify diet in recent andfossil gastropods. These sterols can be usedto determine past ecologies of fossilpatellogastropods, whether resource parti-tioning exists at finer levels, if resource par-titioning has changed through time withinlineages, and to identify specialist versusgeneralist forms. Mapping these data onto aphylogenetic tree will allow me to examinethe evolutionary history of feeding and re-source partitioning of patellogastropods,which may shed light on the role of feedingspecialization in clade diversification.

P1.12BELDEN, L.K.*, MOORE, I.T.,BLAUSTEIN, A.R., Oregon State University,Corvallis, University of Washington, Seattle,Oregon State University, Corvallis. Survival

and the physiological stress response inCascades frog tadpoles exposed to ambi-ent UV-B radiation in the field.

Global environmental changes, includ-ing increases in ultraviolet-B radiation (UV-B; 280-320 nm), are receiving attention frombiologists interested in how these changeswill alter community and ecosystem struc-ture and function. However, we know littleabout how factors such as UV-B affect ani-mals physiologically. Amphibians provide agood model system for examining the physi-ological effects of UV-B exposure becausebasic studies documenting both lethal andsublethal effects have been completed on awide array of species at many life historystages. In this study, we examined the physi-ological stress response, as measured byglucocorticoid hormones, and survival ofCascades frog tadpoles, Rana cascadae,exposed to ambient UV-B in the field for 6weeks. There were no differences in corti-costerone levels between exposed andnon-exposed tadpoles, although survivalwas significantly higher in the tadpolesshielded from UV-B. Even though UV-B ex-posure can be lethal for Rana cascadae tad-poles, in this study we did not observe aphysiological stress response. However, thestress response in this species is poorly un-derstood and there are several factors, in-cluding the length of the study, the ability oftadpoles to perceive UV-B, and the timing ofdevelopment of the stress axis, that couldexplain the lack of a physiological stress re-sponse.

P2.32BENNETT, V.A., STEED, J.N.*, LEE,R.E., KUKAL, O., Miami University, Oxford,OH. Atlantic Low Temperature Systems, Ltd.,Halifax, Nova Scotia. A description ofGynaephora groenlandica hibernacula sitesand behavioral preferences for light, tem-perature, and soil moisture related to micro-habitat selection.

G. groenlandica caterpillars overwinter inhibernacula anchored at the base of rockson the Arctic tundra. At each of two studysites on Ellesmere Island, hibernacula wereconsistently found on the same aspect ofthe rocks, possibly related to prevailing windsand/or patterns of snow accumulation. Hi-

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bernacula temperatures were slightlywarmer and more buffered than ambient tem-peratures. How do caterpillars select suit-able microhabitats for hibernacula? Labo-ratory experiments tested for behavioral pref-erences based on light, temperature, andsoil moisture conditions. Both active cater-pillars and those entering hibernationshowed strong preference for light over darkconditions. Along a 0-25oC temperature gra-dient, most caterpillars settled at the warm-est region (21-25oC), indicating that they mayselect hibernacula sites based on thermalcues. However they do not appear to selectcolder microhabitats, as we had hypoth-esized, as a means of metabolic depressionfor energy conservation in late sumer andfall. Active caterpillars showed no prefer-ence based on soil moisture, however mostcaterpillars entering hibernation preferredlow soil moisture (0-10%), which may be in-dicative of microhabitats where snow meltsearliest in Spring.

11.5 BENNETT, V.A.*, KUKAL, O., LEE,R.E., Miami Univeristy, Oxford, OH, Atlan-tic Low Temperature Systems, Ltd., Halifax,Nova Scotia, Miami University, Oxford, OH.Seasonal metabolic depression and mi-tochondrial degradation in Arcticwoollybear caterpillars, Gynaephoragroenlandica.

Gynaephora groenlandica requires 7-14years to complete its life cycle, overwinter-ing as many times. Because of the short ac-tive season (3-4 weeks in June), these cat-erpillars may spend as much as 90% of theirlives in dormancy without feeding. Thereforeenergy conservation is especially importantfor their survival in this extreme environment.At the end of June, when the majority of arc-tic insects are just beginning their summeractive period, G. groenlandica caterpillarsenter hibernation, probably as a means oftemporally avoiding parasitoids. Therefore,even in hibernation, G. groenlandica expe-rience the warmest summer temperaturesin July and early August that could poten-tially elevate metabolic rate causing deple-tion of energy reserves. To conserve energy,G. groenlandica exhibit a seasonal meta-bolic depression associated with hiberna-

tion: respiration rates of late-season cater-pillars were as much as 50% lower thanthose of active caterpillars, and they wererelatively insensitive to temperature(Q10~1.5). A previous study demonstratedthat cold-acclimated G. groenlandica hadfewer mitochondria in brain and fat body tis-sues than warm-acclimated caterpillars.Could this mitochondrial degradation be themechanism of metabolic depression? Us-ing confocal microscopy and digital imageanalysis, mitochondria were quantified in tis-sues of both active and hibernating stagesof G. groenlandica. Initial data show a 54%reduction in the number of mitochondria infat body tissue of hibernating versus activecaterpillars, and as much as a 65% reduc-tion in the number of mitochondria in muscletissue.

54.5 BERNAL, D.*, DICKSON, K., GRA-HAM, J., Scripps Inst. Oceanography, Cal.State University, Fullerton. Convergencefor high performance swimming inlamnidsharks and tunas. Thermoregula-tion and metabolic biochemistry.

This study documents the shortfin makoshark's (Isurus oxyrinchus) capacity to ther-moregulate and the thermal effects on meta-bolic enzymes activities and compares theresults to tunas. Elasmobranchs and bonyfishes have evolved independently for morethan 400 million years. However, two Re-cent groups, the lamnid sharks and tunas,display remarkable similarities in featuresrelated to swimming performance. Traitsseparating these two groups from otherfishes include a higher degree of bodystreamlining, a shift in position of the aero-bic locomotor muscle (red muscle, RM) thatpowers sustained swimming to an anteriorposition in the body and to near to the verte-bral column, an increased gill surface area,a higher blood oxygen carrying capacity, thecapacity to conserve metabolic heat (i.e.,endothermy), and greater muscle aerobicand anaerobic enzyme activities at in vivotemperatures. The suite of morphological,physiological, and biochemical specializa-tions that define “high-performance fishes”have been extensively characterized in thetunas. This study uses the convergent fea-

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tures of lamnids and tunas in order to gaininsight into the extent that comparable envi-ronmental selection pressures have led tothe independent origin of similar suites offunctional characteristics in distinctly differ-ent taxa. This study tests the hypothesis that,despite differences between teleost andelasmobranch fishes, lamnids and tunas,have evolved morphological and physiologi-cal specializations that enhance their swim-ming performance relative to other sharksand most other high performance pelagicfishes.

P2.95BERTRAM, J.E.A.*, RUINA, A., COX,D.E., KATSANOS, C.S., Florida State Uni-versity, Tallahassee, Cornell University,Ithaca, Florida State University, Tallahassee,Florida State University, Tallahassee. Speed,step length and frequency in human walk-ing: evaluating the optimization criteria.

Locomotion is an active process that in-volves an interaction between physiologi-cal and physical features of an organism.The result of this interaction is the overt func-tional behavior of the system, its capabilitiesand limitations. But can the physiologicaland physical influences be discriminated?We use the walking human as a model sys-tem to investigate the factors influencing gaitpattern, as indicated by the selection of steplength and frequency to provide walkingspeed. We hypothesize that the selection ofthese variables depends on the minimiza-tion of the locomotory cost function underthe explicit circumstances involved, i.e. thesolution is a constrained optimization. Wecompare walking behavior of 6 male and 6female subjects with predictions based onindividual locomotion cost. The results verifythe basic model, but also demonstrate thatother factors influence the outcome as well.

50.3 BETTENCOURT, B.R.*, FEDER, M.E.,University of Chicago. Concerted evolutionand concerted degeneration at the hsp70genes and pseudogenes of the Drosophilamelanogaster species subgroup.

To determine how the hsp70 genes (4-5copies total, at two chromosomal loci) co-evolved with the diversification of the D.melanogaster species subgroup, we se-quenced multiple alleles of each gene in

representative species. The hsp70 genesdisplay strikingly different patterns of molecu-lar evolution among the eight species of thesubgroup. In D. simulans and D.melanogaster, frequent gene conversion ho-mogenizes all the hsp70 coding sequences,diversifies flanking sequences, and interactswith both purifying and balancing selectionto drive rapid concerted evolution. By con-trast, hsp70 pseudogenes are common inD. mauritiana: null alleles of three of the fourhsp70 genes are at high frequency. Thesepseudogenes also participate in gene con-version; copies at different loci share thesame degenerative mutations. The hsp70genes of D. orena, basal member of the sub-group, evolve in a fashion similar to those ofD. simulans. While hsp70 expression level,thermotolerance, and thermal niche breadthare strongly coupled to the hsp70 genes inD. melanogaster, the functional copy num-ber and relative "health" of the hsp70 ge-nome is only a fair predictor of these traits inother species. If, when, and how natural se-lection acts on the hsp70 genes varies in alineage- and locus-specific fashion.

P2.84 BETZ, O.*, MUMM, R.,Universitaet Kiel, Tieroekologie,Universitaet Kiel, Phytopathologie. Thepredatory legs of Philonthus marginatus(Coleoptera,Staphylinidae): functionalmorphology and tarsal ultrastructure.

Within the Coleoptera, no predatory legshave become known thus far. However, withinthe staphylinid genus Philonthus represen-tatives of the subgenus Onychophilonthusare distinct from other subgenera by thestructure of their prolegs: both sexes haveelongated coxae and enlarged tarsomeresI-IV. The claws can be bent downward to alarge extent, thus almost setting against theventral side of tarsomere V. We present theresults of (a) behavioural observations con-cerning predatory performance, (b) motionanalysis of the predatory strike, and (c) mor-phological examinations of the prolegs bylight, scanning and transmission electronmicroscopy. These examinations were aimedto develop a functional model of this ad-vanced prey capture mechanism. The preda-tory behavior of these beetles can be subdi-

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vided in three parts: (a) attempting an am-bush, (b) predatory strike, and (c) formationof a catching basket. The mean total dura-tion of the strike from the onset of the prolegtill the first prey contact amounts to 31.6 ms.The movements of the prolegs during thestrike can be subdivided in three compo-nents: (1) upward swing, (2) downward strike,(3) withdrawal. The structure of the coxo-tro-chanteral articulation and the high speed ofthe downward strike (7 ms) suggest a pre-stress mechanism, consisting of the co-con-traction of the trochanterofemoral flexor andlevator muscles. In addition, a coxal projec-tion that fits into a trochanteral groove whenthe leg is flexed, serves as a cuticular sup-porting structure. The ultrastructure of theprotarsi I-III demonstrates the rich develop-ment of epidermal glands, which probablyproduce an adhesive secretion. By thismeans, under mediation of tarsal adhesivesetae, the prey can be fixed at the momentof contact, thus enabling the beetles to cap-ture even fast-fleeing prey such as spring-tails.

23.6 BIRCH, J.M.*, DICKINSON, M.H., Uni-versity of California, Berkeley. Dynamic stallof a flapping appendage in the absence of aspiral vortex.

Recent studies of insect flight describehow dynamic stall and the formation of aleading edge vortex generate large lift forcesfor insects. This leading edge vortex, alongwith forces generated through rotation andwake capture, accounts for all lift necessaryfor insects to fly. This vortex is presentthroughout the translation portion of thewingbeat cycle and has been shown to growin size from the base toward the wing tip. Ithas been hypothesized that fluid spirals out-ward through the center of this vortex, drain-ing energy from the core, allowing the vor-tex to remain stable throughout the stroke.Using a robotic flapping model of a Droso-phila wing, we visualized the flow of fluidaround the wing and reconstructed the flowstructure using digital particle imagevelicometry. At mid-downstroke, the leadingedge vortex consists of a large sheet of vor-ticity that stretches back from the leading totrailing edges of the wing. However, unlike

the flow pattern seen in the hawkmoth,Manduca sexta, flow within the leading edgevortex was < 5% of wing tip velocity. Wetested the idea that this axial flow was nec-essary to maintain the stability of the lead-ing-edge vortex. Using both a wall that cir-cumscribed the wing sweep as well asfences on the wing, we inhibited axial flowthrough the vortex core. When axial flowwas not permitted off the wingtip (the wallcase), the tip vortex detached from the wingmore distally and forces generated by thewing increased by at least 14%. Fences hadlittle effect on force generation. From theseexperiments we hypothesize that in Droso-phila, axial flow has little effect on the stabil-ity of the leading edge vortex, and thus itssize is not the limiting factor when determin-ing the performance of a flapping append-age.

P1.61BIRCHARD, G.F.*, DAUGHERTY,C.H., George Mason University, Fairfax,Victoria University of Wellington, NewZealand. Energetic of development in thefairy prion (Pachyptila turtur).

Embryos of the Procellariiformes arenoted for their very long incubation times.The limited data available on embryos fromthis group indicates that these long devel-opment times are associated with increasedcosts of development. We measured theoxygen consumption rate of developingembryos of the fairy prion (Pachyptila turtur),a small procellariiform, from early in incuba-tion until internal pipping (IP) occurred. Av-erage egg mass in this species was 25g.The oxygen consumption rate showed anexponential rise with time. There appearedto be a short plateau period two days priorto IP which occurred on day 42 of an esti-mated incubation time of 44.5 days. The pre-IP oxygen consumption rate averaged 238ml O2/d. Integration of the area under thecurve to the time of IP gave a total of 2924 mlO2 consumed, a pre-IP cost of developmentof about 57.4 kJ. The incubation time of thefairy prion is 188% of the value predictedfrom existing allometric equations. The pre-IP energy consumption was not significantlydifferent from predicted values. The cost ofdevelopment was increased (184% of pre-

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dicted values) as previously observed in thisgroup. Analysis of deviations from predictedvalues for incubation time and cost of de-velopment for procellariiform embryosshows a significant effect of egg mass. De-creasing egg mass shows a consistent in-crease in the deviations observed.

P2.93BISHOP, K. , Brown University. Evolu-tionary patterns in bat wing shape.

Among mammals, bats are the only groupto have evolved powered flight. The changeswhich allowed the adoption of this locomo-tor mode include the modification of the fore-limb into a wing. Features of the wing shapesuch as wing loading, aspect ratio, and tipindex affect the aerodynamic performanceof the wing. These measurements have beenmade by Norberg and Rayner, who analyzedthem in an ecological context, but they haveyet to be examined in an evolutionary con-text. I have mapped these measurementsonto a well-supported phylogeny of the or-der Chiroptera in order to evaluate evolu-tionary patterns in wing shape.

36.6 BIXLER, A., TANG-MARTINEZ, Z.*,University of Missouri-St. Louis. Mate choicein prairie voles: effects of genetic related-ness and familiarity.

Prairie voles, Microtus ochrogaster, aremonogamous rodents. We examined themating choices of sexually inexperiencedmale and female prairie voles in two-waychoice tests under 3 different conditions.Subjects were tested with targets that were1) either a familiar sibling or an unrelatedand unfamiliar vole; 2) a sibling and an un-related vole, both of which were unfamiliar;or 3) two siblings, where one was familiarand the other unfamiliar. Intrommission wasthe criterion for mating. In condition 1, allvoles that mated did so with the unfamiliarand unrelated conspecific. In condition 2,there was no significant preferences be-tween the two targets. In condition 3, onlyone of 17 subjects mated, suggesting thatvoles avoid mating with siblings even whenthey are unfamiliar to the subject. The re-sults of other measures related to reproduc-tive behavior (e.g., time visiting, anogenitalinvestigation, time in contact, agonistic in-

teractions) will also be reported. In mostcases these measures were consistent withthe mating preferences. However, we alsofound that interaction of pairs that matedwere significantly more agonistic as com-pared to those of pairs that did not mate.Additionally, social preference (time spentvisiting a target) did not always correspondto mating preference. We conclude that bothrelatedness and familiarity are important inthe mate choices of prairie voles and thattime spent visiting is not an adequate mea-sure of mating preferences.

P2.10BLACKBURN, D.G.*, JOHNSON, A.R.,PETZOLD, J.L., Trinity College, Hartford. His-tology of the extraembryonic membranes ofthe oviparous corn snake, Elaphe guttata.

The extraembryonic membranes of am-niote eggs serve vital nutritional and respi-ratory functions throughout development.However, very little is known about the struc-ture and function of these membranes inoviparous reptiles. We examined extraem-bryonic membranes of the corn snakeElaphe guttata (Colubridae), using resin -embedded tissues sectioned on glassknives. Following oviposition, the embryosdevelop a chorioallantois as well anomphalallantoic membrane. The chorioal-lantois is highly vascularized, and its capil-laries are separated from the inner lining ofthe eggshell by a bilayered epithelium thatprogressively thins during development.Small basophilic granules, possibly takenup from the eggshell, accumulate in apicesof the epithelial cells. Depletion of yolk leadsto expansion of the chorioallantois at theexpense of the yolk sac. The omphalallantoicmembrane forms through penetration of theallantois into the yolk cleft. The isolated yolkmass (IYM) undergoes progressive reduc-tion, transforming into isolated patches ofyolk droplets that are underlain and sur-rounded by the allantois. Yolk of the IYM ap-pears to be digested by the bilaminaromphalopleure as well as by the allantoisand motile cells with phagocytic capabili-ties. Diminution of the IYM and the overlyingepithelium lead to close approximation ofthe allantoic capillaries to the eggshellthroughout the abembryonic hemisphere of

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the egg. Consequently, for the last weeks ofdevelopment, the egg is surrounded by thinvascularized membranes that presumablyfunction in respiratory exchange. To betterunderstand their functional morphology, wecurrently are examining cell ultrastructure ofthese membranes with electron microscopy.

64.5 BLACKSTONE, N.W., Northern IllinoisUniversity Redox state, reactive oxygen spe-cies (ROS), and adaptive growth of hydroidcolonies.

Redox chemistry, involving the transferof electrons and hydrogen atoms, is centralto energy conversion in respiration, andcontrol of gene expression by redox statecommonly occurs in bacteria, allowing rapidresponse to environmental changes. Colo-nial hydroids often encrust surfaces overwhich the food supply varies in time andspace; hence, in these organisms redox con-trol of the development of feeding structures(polyps) and gastrovascular connections(stolons) could be similarly adaptive, allow-ing colonies to adjust the timing and spac-ing of these structures in response to a vari-able food supply. Feeding triggers strongcontractions of polyp epitheliomuscular cells,resulting in high rates of gastrovascular flow.In fed polyps, this metabolic demand shiftsthe redox state of these cells in the directionof oxidation and diminishes the rate of for-mation of mitochondrial ROS. On the otherhand, after 24 h without food, polypepitheliomuscular cells become quiescent,redox state shifts in the direction of reduc-tion, and formation of mitochondrial ROSincreases. Perturbations of redox state andROS can also be initiated using uncouplersof oxidative phosphorylation and inhibitorsof the mitochondrial electron transport chain.The effects on colony pattern formation aresimilar; relative oxidation results in high ratesof polyp and stolon tip initiation, while rela-tive reduction results in low rates. As in othersystems, ROS may mediate the effects ofredox state; high levels of ROS may sup-press the gene activity that leads to polypand stolon tip initiation, while low levels ofROS may be permissive in this regard. Inthis way, metabolic demand, redox state, andROS may interact to control pattern forma-

tion in hydroid colonies and to allow adap-tive growth forms in response to the foodsupply and other environmental factors.

55.3 BLANK, J.M.*, DAVIE, P.S.,MORRISSETTE, J.M., BLOCK, B.A., StanfordUniversity, Pacific Grove, CA, Massey Uni-versity, Palmerston North, New Zealand,Stanford University, Pacific Grove, CA,Stanford University, Pacific Grove, CA. Ef-fects of temperature on cardiac performancein yellowfin tuna.

Tunas are remarkable among teleostsfor their endothermy, high metabolic ratesand high capacity for exercise. While tunaswarm their swimming muscles and viscera,their hearts are thought to remain near am-bient temperature. This raises the possibilitythat cold water may impair cardiac perfor-mance in vivo, limiting the scope for metabo-lism of tuna in the wild. We have investigatedthe effects of acute temperature change oncardiac function in yellowfin tuna (Thunnusalbacares) using an in situ perfused heartpreparation. We found that as temperaturewas reduced, heart rate fell but stroke vol-ume increased. Heart rate exhibited a Q10of ~2.0 between 15ƒC and 25ƒC whilestroke volume showed a Q10 of ~-0.5 overthe same range. Cardiac output was 15-30%lower at 15ƒC than at 20ƒC or 25ƒC. Maxi-mal output pressure attainable without flowcompromise remained nearly constant at 12kPa over this temperature range. This reduc-tion in cardiac performance with decreasingtemperature suggests that cold water mayreduce blood flow and hence oxygen deliv-ery in wild yellowfin tuna.

4.5 BLOB, R.W.*, PACE, C.M.,WESTNEAT, M.W., Field Museum, Chicago,IL. Testing functional correlates of habitatspecialization: swimming and walking inspiny softshell and slider turtles.

Although many freshwater turtles fre-quently travel long distances over land, sev-eral species are morphologically specializedfor swimming and spend little time out ofwater. To test the impact of locomotor spe-cialization on limb kinematics and motorcontrol, we used EMGs and high-speedvideo to compare hindlimb motor patterns

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during swimming and walking in the gener-alized turtle Trachemys scripta (red-earedslider) and the aquatic specialist Apalonespinifera (spiny softshell). Kinematic distinc-tions between the species indicate thataquatic specialization need not impede ter-restrial locomotion. For instance, in bothswimming and walking, femoral excursionis nearly twice as great in softshells (70-75ƒ)as in sliders (35-40ƒ). However, in softshellsthe knee is held significantly straighter dur-ing walking than during swimming, suggest-ing that softshell knee extensors may oper-ate at shorter lengths less optimal for forcegeneration during walking. Motor patternsof softshells and sliders also show severaldifferences; however, the modulation of mo-tor patterns between swimming and walk-ing is similar in both species. In both slidersand softshells, the knee extensorfemorotibialis shows a second burst duringwalking that correlates with a protractivephase of knee extension. In addition, thetiming of femoral protractor activity does notchange significantly between swimming andwalking in either species. Together, our analy-ses of hindlimb kinematics and muscle ac-tivity in these species suggest that measure-ments of muscle length changes may indi-cate key distinctions in how habitat special-ists and generalists modulate muscle func-tion between behaviors. NIH 5F32NS10813-01/02 to RB and ONR N000149910184 toMW.

P1.54B BLOOM, A. J., SMART, D. R.,NGUYEN, D. T., University of California,Davis. Elevated carbon dioxide concentra-tions inhibit nitrate assimilation in wheatshoots.

Fluxes of CO2 and O2 from the shoots ofwheat (Triticum aestivum) demonstrated thatexposure to elevated CO2 concentrationsstrongly inhibited shoot NO3

- assimilation.Accordingly, elevated CO2 concentrationsenhanced shoot growth of wheat plants re-ceiving NO3

- nutrition to only half the extentof plants receiving NH4

+ nutrition, and el-evated HCO3

- concentrations interfered withthe translocation of NO2

- into wheat and peachloroplasts. If CO2 inhibition of NO3

- assimi-lation were common among species, it

would provide a mechanistic explanation forseveral responses of plants to elevated CO2

including photosynthetic acclimation to CO2,CO2 inhibition of respiration, and intraspe-cific and interspecific variation in plantgrowth under elevated CO2.

54.4 BOETTGER, S.A.*, MCCLINTOCK, J.B.,University of Alabama at Birmingham. The ef-fects of organic and inorganic phosphate onmuscle contraction and acetyl cholinesteraseactivity of the nearshore echinoid Lytechinusvariegatus.

Lytechinus variegatus is a commonnearshore sea urchin that is exposed tophosphate pollutants. Sea urchins were col-lected in April, 2000 from Saint Joseph's Bayin the northern Gulf of Mexico. Individualswere divided into a control (artificial seawater), sea water containing three concen-trations of inorganic (sodium phosphate); orthree concentrations of organic (triethyl phos-phate) phosphate. Individuals were main-tained for an 8-week period, dissected andthe Aristotle's lantern retractor muscles ex-tracted individually. Each muscle was at-tached to a strain gage, stimulated electri-cally, and muscle contractions (g force/mmmuscle length) recorded. When comparedto the control group, force of contraction in-creased significantly in individuals main-tained in increasing concentrations of bothphosphates. Following the direct coloringthiocholine assay, acetyl cholinesterase ac-tivity was assessed by embedding and stain-ing retractor muscles from the Aristotle's lan-tern, tube-feet, and gut, and counting the oc-currence of fully-stained motor endplates/mm2 . Acetyl cholinesterase activity in thesesame muscles was also assessed througha colorimetric assay. The number of fully-stained motor endplates and the enzymaticactivity of acetyl cholinesterase decreasedin individuals maintained in increasing con-centrations of organic phosphate when com-pared to the control group. No change oc-curred in individuals exposed to inorganicphosphate. These results indicate that whilephosphate exposure has a significant effecton muscle contraction in Lytechinusvariegatus, the inhibition of acetyl cholinest-erase, an enzyme critical to muscle relax-

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ation, can only be a potential contributingfactor in individuals maintained in organicphosphate.

P1.80BOILY, P.* P., KNIGHT, F.M., UniversityNew Orleans, LA, University of the Ozarks,AK. Cold-induced hyperthermia and maxi-mum metabolic rate in the nine-banded ar-madillo.

In response to cold temperature expo-sure, the nine-banded armadillo (Dasypusnovemcinctus) undergoes an increase inmetabolic rate concomitant with an increasein core temperature above thermoneutralvalues. This physiological response is incom-patible with standard models of the controlof body temperature in non-hibernatingmammals where a negative feedback sys-tem inhibits heat production if core tempera-ture rises above the setpoint. One possibleexplanation for this cold-induced hyperther-mia is that resting armadillos are slightly tor-pid and that cold exposure causes the ani-mals to arouse and increase their core tem-perature to a higher setpoint in order to in-crease metabolic heat production capacity.We tested this hypothesis by exposing ar-madillos to cold temperatures while simul-taneously gas exchange rates (VO2 andVCO2) and core temperature at four loca-tions (rectal 8cm and 16cm; esophageal 8cmand 16cm). Core temperatures were highlycorrelated to each other and changed dur-ing cold exposure according to the samepattern, thus indicating that cold-induced hy-perthermia truly reflects a change in the in-ternal heat content of the animal rather thana decrease in the size of the core. Peak VO2

occurred approximately at the same time aspeak core temperatures, thus supporting thehypothesis that cold-induced hyperthermiafavors high metabolic rates. Peak VCO2 of-ten occurred well after the peak in core tem-peratures, when animals were hypothermic.This is likely the result of increased CO2excretion resulting from the buffering of lac-tate by bicarbonates rather than an increasein the rate of CO2 production. Funded byNSF (IBN-9723065 and ROA suppl.).

P2.66BOLDUC, M.*, BLIER, P.U., DUTIL, J.-D., University du Quebec, Rimouski, Univer-sity du Quebec, Rimouski, Government ofCanada, Fisheries and Oceans. The impactof mitochondial thermal sensitivity on theswimming capacity of Arctic charr.

The swimming performance of fish lieson there capacity to convert chemical en-ergy into mechanical energy, trough the con-traction of axial muscle. During sustainedswimming, ATP required for contraction ismostly supplied by mitochondrial metabo-lism. Oxygen consumption is thus propor-tional to work intensity. At low temperature,the aerobic capacities of fish decrease, aswell as maximal sustainable swimmingspeed. However, for many species cold ac-climation increases the aerobic capacity ofmuscle trough an increase of mitochondrialvolume-density and/or of mitochondrial en-zymes concentration. This compensationsuggest that swimming capacities impair-ment at low temperature is related to a de-crease in mitochondrial catalytic capacities.To test this hypothesis, the aerobic scope foractivity of Arctic charr (Salvelinus alpinus)was measured at four different temperatures(1, 6, 12 and 18 C). In each fish, mitochon-dria were extracted from red muscle of oneside of the fish. Mitochondrial respiration(pyruvate and malate as substrates) wasmeasured under the same temperatures. Cy-tochrome c Oxidase activity was assayed inthe mitochondrial preparation and in wholered muscle of the other side of the fish. Thisallowed us to estimate maximal mitochon-drial respiration rate in fish red muscle andcompare it to aerobic scope for activity un-der different temperatures.

P1.94 BONINE, K.E.*, GLEESON, T.T.,GARLAND, T. Jr., University of Wisconsin,Madison, University of Colorado, Boulder,University of Wisconsin, Madison.Phrynosomatid lizards show parallel varia-tion in sprint speed and muscle fiber-typeproperties.

Phrynosomatids are comprised of 3 dis-tinct subclades ((sand lizards, horned liz-ards), Sceloporus group)) that exhibit greatvariation in habitat, behavior, and generalbody plan. This family also varies widely in

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maximal sprint speed; sand lizards are ex-ceptionally fast, horned lizards are slow, andthe Sceloporus group is intermediate. Thesedifferences are paralleled by relativehindlimb span (Bonine and Garland 1999, JZool Lond 248:255-265). We examined theiliofibularis (IF) muscle to determine if fiber-type composition varies similarly. Sampling11 species (44 indivs.), we used histochemi-cal assays for myosin ATPase (fast-twitchcapacity) and succinic dehydrogenase (oxi-dative capacity) to classify fibers as fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG), or slow-twitch oxidative(SO). Sand lizards have a high proportion ofFG fibers (mean 67%) and a low proportionof FOG (29%); horned lizards have lowerFG (28%) and higher FOG (61%); membersof the Sceloporus group, which are presumedto reflect the phrynosomatid ancestral state,are intermediate for both FG (45%) and FOG(44%). Across all 11 species, %FOG and%FG are strongly negatively correlated (r = -0.95). Analysis with phylogenetically inde-pendent contrasts indicates that this relation-ship is entirely attributable to the divergencebetween sand and horned lizards. Neitherthe proportional area of the IF in the hindlimb,nor the cross-sectional areas of FG (11 spp.mean 417 Mmm2, s.e. adj. for body mass 13.8[mean log body mass 1.0045]), FOG (260,9.5), and SO (137, 12.5) fibers, differ amongthe 3 subclades. However, mass-adjustedhindlimb cross-sectional area is lower forhorned lizards. [NSF Grad. Fellowship KEB,NSF IBN-9724140 TTG, IBN-9723758 TG]

56.2 BOORSE, G.B., DENVER, R.J.*, Uni-versity of Michigan. Changes in hypothalamiccorticotropin-releasing hormone (CRH)content during environmentally-inducedmetamorphosis in the Western spadefoottoad (Spea hammondii)

Western spadefoot toads (Speahammondii) are desert dwelling amphibianswhose tadpoles can accelerate metamor-phosis as their ponds dry, thereby escapingdesiccation. Corticotropin-releasing hor-mone (CRH) may transduce the environmen-tal signal into an endocrine response thatdrives metamorphosis. To further understandthe role that CRH plays in environmentally-

induced metamorphosis we developed andvalidated a CRH radioimmunoassay (RIA)to monitor changes in hypothalamic CRHcontent following exposure to low water inthe laboratory. We generated a rabbitpolyclonal antiserum against synthetic Xe-nopus laevis CRH. This RIA detects verte-brate CRH peptides with high sensitivity andshows low cross-reactivity with the CRH-likepeptides sauvagine, urotensin and urocortin.Molecular cloning of the S. hammondii CRHcDNA shows that the sequence of the ma-ture peptide is identical to the Xenopus se-quence. Thus, this RIA is homologous forboth X. laevis and S. hammondii. We vali-dated the CRH RIA for measurement of pep-tide content in acid hypothalamic extracts.We demonstrate that CRH-binding protein(CRH-BP), which could potentially interferewith the RIA, is present in S. hammondii brain.However, very little biologically active CRH-BP remains after the acid extraction. Addi-tion of varying amounts of recombinantmouse CRH-BP to the standard curve in theRIA shows that, while the BP can interfere athigher concentrations, the amount remain-ing after acid extraction does not interferewith the CRH RIA. Using this RIA, we showthat S. hammondii tadpoles exposed to lowwater level exhibit brain-region specificchanges in CRH content. (Supported by NSFgrant IBN9974672 to RJD and a NSFpredoctoral fellowship to GCB)

P1.77BORRELL, B.J.*, LADUC, T.J.,DUDLEY, R., University of Texas, Austin.Physiological cost of head-body tempera-ture differences in snakes.

Head-body temperature differentialsobserved in reptiles and other ectothermsmay be important for central nervous sys-tem functioning, but the maintenance cost ofthis differential in terms of water loss hasnever been studied. Using infraredthemography, we measured head-body tem-perature differentials in three snake families:viperids, colubrids, and boids. Some snaketaxa maintain a temperature differentialgreater than 3 degrees C via respiratory cool-ing. We estimate the physiological cost as-sociated with such water loss andcomparethese costs among clades and habitats. We

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also discuss the benefits of respiratory cool-ing in terms of the thermoreceptive capabili-ties of boids and viperids.

48.3 BOSTWICK, K.S., University of Kan-sas. Sexual selection for wing-sounds asso-ciated with convergent wing shape evolu-tion between three clades of manakins (Aves:Pipridae).

Males of most of the ~40 species of Neo-tropical manakins (Aves: Pipridae) performenergetic courtship displays on lek territo-ries. In nearly half of the speices, males pro-duce mechanical wing sounds during thesedisplays. Recent phylogenetic hypothesesindicate wing sound production may haveevolved as many as three times indepen-dently in the family. Repeated evolution ofmechanical sounds allows comparativeanalysis of wing morphology in relation tosound production. Specifically, this researchaddresses (1) if wing shape has beendetectably modified in the mechanical soundproducing lineages, and (2) if so, are thereany commonalities in shape change be-tween lineages. I measured the lengths andwidths of 4 wing bones for 42 species ofmanakins and allies, including representa-tives from each of the three mechanicalsound producing clades. Three measuresof overall body size were also made. Wingshape was characterized by the second prin-ciple component of a PCA, and mechanicalsounds were categorized according to com-plexity, loudness, and repertoire sizes ofspecies. Independent contrast of speciesvalues of these variables were regressed toshow that wing shape has changedconvergently in mechanical sound produc-ing lineages. Wings of mechanical soundproducing clades have shorter, thicker ulna,shorter carpometacarpi, and thicker scapulablades then non-mechanical sound produc-ing manakins. These result support the hy-pothesis that sexual selection has causedwing morphology to evolve in response tofunctional requirements for mechanicalsound production.

P1.21BOSWORTH, C.A.*, REES, B.B., Uni-versity of New Orleans, Louisiana. Patternsof protein expression in zebrafish muscle

during hypoxia.Alterations of protein expression may

be important in determining the capacityof an organism to tolerate low oxygen con-centrations. Most previous studies of fishexposed to hypoxia have examinedchanges in individual proteins. Here, wereport on the use of two-dimensional elec-trophoresis (2DE) to investigate the effectsof hypoxia on patterns of global proteinexpression in the zebrafish, Danio rerio.Zebrafish were held for 48 h in water hav-ing a dissolved oxygen concentration of10% of the air-saturated value, a treatmentknown to increase the survival time ofzebrafish during more severe hypoxia.Proteins from white muscle were solubi-lized, separated by 2DE, and stained withsilver. Among the proteins resolved was arelatively prominent 50 kDa polypeptidethat appeared to have at least 2 isoformsdiffering in isoelectric point (pI). The rela-tive abundance of the 2 forms was alteredby hypoxia, with the more basic form pre-dominating in extracts prepared from hy-poxic fish. This change in pI is consistentwith post-translational modification, per-haps dephosphorylation, of the proteinduring hypoxia. The polypeptide is similarin size and pI to mammalian pyruvate ki-nase (PK), an enzyme known to be regu-lated by reversible phosphorylation. Achange in phosphorylation state ofzebrafish PK during hypoxia could resultin a more active enzyme at physiologicalsubstrate concentrations and contribute toan increased capacity for glycolytic ATPgeneration during hypoxia. Supported byNational Science Foundation grant IBN9723050.

66.3 BOTTON, M. L.*, LOVELAND, R. E.,Fordham University, Rutgers University Thediminishing abundance of horseshoe crabsin Delaware Bay: potential impacts on mi-grant shorebirds.

Migratory shorebirds on staging areastypically concentrate their feeding on unusu-ally abundant prey species, enabling themto rapidly increase mass prior to the next legof their migration. Delaware Bay is the mostimportant staging area on the Atlantic coast

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of North America for shorebirds during theirSpring (northward) migration; here, birdsprimarily feed upon horseshoe crab eggson sandy intertidal beaches. The commer-cial fishery for horseshoe crabs, which col-lects the animals for bait in eel and whelktraps, expanded substantially from about1990 to 1996. Based on surveys of six Dela-ware Bay, NJ beaches, horseshoe crab eggabundance has decreased in conjunctionwith the expansion of this fishery. During theperiod 1985-1991, relatively few surfacesediment samples (0 to 5 cm depth) con-tained zero horseshoe crab eggs, and atleast 30% of these samples contained>10,000 eggs per square meter. In contrast,in the period 1996-1999, the frequency dis-tribution is strongly shifted toward the loweregg density intervals. The likelihood of ashorebird encountering surface sedimentswith zero eggs has increased from about10% in 1985 to over 50% in 1999. Thesetrends in egg density are also corroboratedby significant decreases in the abundanceof stranded horseshoe crabs over the pe-riod 1978-1999. Shorebirds in Delaware Baymay be adversely impacted by further de-creases in the horseshoe crab resource, byextending foraging time and/or intensifyingintra- and interspecific competition for eggs.

P3.94BOWDEN, R.M.*, EWERT, M.A.,LIPAR, J.L., NELSON, C.E., IndianaUniveristy, Bloomington. Hormones in yolklayers and offspring sex ratios vary season-ally in turtles.

The presence of hormones in yolks offreshly laid eggs has recently been describedin reptiles. These hormones are probably ofmaternal origin. Their potential to influenceoffspring sex may be enhanced by tempera-ture-dependent sex determination. Profilesof circulating hormones have been de-scribed for several temperate turtles. Thereappears to be a general pattern to the sea-sonal oscillations in testosterone (T), proges-terone (P), and estradiol (E2). To determinewhether this pattern is represented in eggyolks, we measured T, P, and E2 concentra-tions via radioimmunoassay in three layersof yolk from eggs of early and late nestingfemale painted turtles (Chrysemys picta).

Also, we extracted small yolk biopsies tomeasure T and E2. We compared the hor-mone concentrations from the biopsied eggsto the sex ratio of their clutchmates to deter-mine whether maternally-derived yolk hor-mones influence offspringsex. T and P con-centrations were highest in the exterior layerof yolks and E2 concentrations were lowest.The same layered pattern of hormones oc-curred in red-eared sliders (Trachemysscripta elegans). Yolk E2 concentrations var-ied seasonally in painted turtles, with lowlevels in all yolk layers early in the nestingseason and higher levels in all layers lateron. Neither T nor P exhibited significant sea-sonal variation. In the yolk biopsies, therealso was seasonal variation in E2, but not inT. We found a significant correlation with sexratio for E2, but not for T.

6.5 BOYLE, H.J.*, GRAHAM, J.B., Univer-sity of California, San Diego. Acquisition ofcharacters facilitating amphibious behaviorin the oxudercine fishes.

The evolutionary sequence of characteracquisition associated with amphibious airbreathing and terrestrial life was examinedin the oxudercine fishes (Gobiidae). Includedamong the 10 genera (35 species) ofoxudercines are forms with little to no spe-cializations for amphibious life as well asthe four genera (25 species) of the amphibi-ous, air-breathing mudskipper clade. Fivecharacters hypothesized to be associatedwith amphibious life (presence of a flattenedeye lens, reduced gill surface area to massratio, increased buccal chamber volume tomass ratio, inability to repay an oxygen debtin water after exercise, and presence of anair phase inside the burrow) are expressedin one mudskipper species, Periophthal-modon schlosseri. Mapping of the characterstates of six genera (Oxuderces, Pseud-apocryptes, Scartelaos, Boleophthalmus,Periophthalmus, and Periophthalmodon)onto a cladogram generated using morpho-logical data indicates the following evolu-tionary sequence for the transition from anexclusively aquatic existence to amphibiouslife: deposition of air inside the burrow, in-creased buccal chamber volume to massratio, decreased gill surface area to mass

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ratio, loss of a round lens, and loss of thecapacity to repay an oxygen debt in waterafter exercise. The hypothesized sequenceof acquisition of morphological, behavioral,and physiological characters demonstratesthe evolution of progressive specializationsfor an amphibious existence in themudskipper clade. (supported by NSF-9604699)

34.2 BRADLEY,T.J., University of California,Irvine. The discontinuous gas exchange cyclein insects may serve to reduce oxygen sup-ply to the tissues.

The discontinuous gas exchange cycle(DGC) in insects, consists of a closed phase(C) during which the spiracular valves at theopenings of the tracheae are closed, a flut-ter phase (F) when the spiracles open andclose rapidly, and an open phase (O) inwhich the spiracles are open, allowing thefree exchange of respiratory gases betweenthe tracheal lumen and the outside air. Earlyworkers such as Buck and Levy &Schneiderman, suggested that the DGCserves to reduce respiratory water loss.More recently, Lighton has suggested thatthe DGC serves to increase internal carbondioxide concentrations, thereby facilitatingthe release of carbon dioxide into environ-ments, such as underground burrows, whichare rich in this gas. We have been conduct-ing studies using the Hemipteran Rhodniusprolixus, an insect that takes a bloodmealup to ten times its previous body volume. Inthe days following feeding, the insect re-mains completely still, yet its metabolic rateincreases up to 14-fold. We have been us-ing this unusual behavior to examine theeffects of metabolic rate on the DGC. Wefound that the spiracles appear to close verytightly when metabolic rates are low, but donot close fully when the rates are higher. Wewill present data from other laboratories thatdemonstrate similar effects when metabolicrate is varied by temperature or when oxy-gen tensions are manipulated. I proposethat the DGC may serve to reduce the sup-ply of oxygen to the tissues during periodsof low metabolic rate. Oxygen is toxic to cells,even at ambient concentrations, and insectsmay use the DGC to provide adequate gas

exchange while reducing oxidative damageto tissues during periods of reduced oxygendemand. Supported by NSF grant IBN0079501.

P2.88BRAINERD, E.L., LANDBERG, T.*,University of Massachusetts, Amherst. Ven-tilatory mechanics of an elongate aquaticsalamander: Amphiuma tridactylum.

We investigated the mechanism of lungventilation in an aquatic salamander,Amphiuma tridactylum. Breathing epi-sodes, which occur at intervals rangingfrom less than 1 to 50 min, are character-ized by a single large exhalation followedimmediately by a variable number of buc-cal pumps which refill the lungs. Unlikethe majority of salamanders which use atwo-stroke buccal pump, Amphiuma usesa four-stroke buccal pump. Four-strokebreathing is also found in another aquaticsalmander (Cryptobranchus), in anaquatic frog (Xenopus), and in basal ray-finned fishes (eg. Amia and Lepisosteus),and probably evolved independently in allof these taxa. In Amphiuma, the combina-tion of relatively large tidal volumes and afour-stroke buccal pump results in highlyeffective exchange of pulmonary gaseswith the environment. Electromyographyof the M. transversus abdominis (TA), ab-dominal pressure measurements andblow-hole pneumotachography indicatethat both passive and active mechanismscontribute to exhalation. Exhalation gen-erally begins in the absence of abdominalmuscle activity. This “passive” phase ofexhalation may be driven by tissue elas-ticity, hydrostatic pressure, and/or smoothmuscle contraction in the lungs. In mostbreaths, the passive phase is followed byan active phase in which an increase inpleuroperitoneal pressure, powered by ac-tivity in the TA, joins the passive exhala-tion mechanisms. The use of hypaxialmucles to power active exhalation has nowbeen found in five salamander families(Sirenidae, Cryptobranchidae, Proteidae,Ambystomatidae, and Amphiumidae), pro-viding evidence that aspiration breathingin amniotes may have evolved in twostages: first active exhalation only and sub-sequently the addition of active inhalation.

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6.2 BRAINERD, E.L.*, MURRAY, S.S.,University of Masachusetts Amherst. Pat-terns of genome size evolution intetraodontiform fishes.

We used flow cytometry to measure ge-nome size (pg of DNA per diploid cell) in15 species belonging to 7 tetraodontiformfamilies and subfamilies. Previous work-ers have found that members ofTetraodontidae (smooth puffers) have thesmallest genome size of any vertebratemeasured to date (0.8 pg vs. a mean of 2.0pg for all teleosts). We found that this tinygenome is present in members of bothtetraodontid subfamilies indicating that theprimitive condition for Tetraodontidae wasa genome size of 0.8ñ0.9 pg. In contrast,Diodontidae (spiny puffers, sister group toTetraodontidae), possess a genome whichis about two times larger (1.60 pg). Molamola, a member of the sister group toDiodontidae+Tetraodontidae, also doesnot have a particularly small genome(1.70 pg). The most parsimonious expla-nation for this pattern is that the primitivecondition for Molidae+ (Diodontidae+Tetraodontidae) is a genome size of1.60ñ1.70 pg, indicating that the tiny ge-nome size of smooth puffers is a derivedcharacter unique to tetraodontids. Previ-ous workers have proposed that the lossof anatomical parts in puffers (no ribs, nopelvis, few vertebrae) might be related tothe loss of genetic material in these fishes.Our results do not support this hypothesisbecause molids and diodontids are miss-ing just as many bits and pieces as smoothpuffers, yet they do not have particularlysmall genomes. We propose that thesmooth puffers are a good model systemin which to study the evolutionary mecha-nisms of genome size reduction because:(1) they have an exceptionally small ge-nome; (2) their closest outgroups havemuch larger genomes; and (3) asmoothpuffer, Fugu rubripes, is being usedas a model organism for gene identifica-tion and molecular tools emerging fromthis work will be useful in studies of ge-nome size evolution in these fishes.

28.1 BRAMBLE, D.M.*, LIEBERMAN, D.E.,DALEY, M.A., Universityof Utah, Salt LakeCity, George Wash. University, Wash. D.C.,Harvard University, Cambridge. Mechanicsof head-neck stabilization in running hu-mans: implications for hominid evolution.

Adequate head-neck stabilization oughtto be vital to any running mammal but thephenomenon has been little studied. Weinvestigated the mechanical basis of cranio-cervical stability in humans during treadmillwalking and running. Quantitative measuresof head-neck and arm motion were obtainedfrom high-speed videography as well assurface mounted accelerometers. Corre-sponding activity patterns in the trapeziusand biceps muscles were also monitored.Our findings show that the mechanical inter-actions between the head-neck complexand arms are strikingly different in the walkand run regardless of speed. The timing oftrapezius muscle activity relative to the stepcycle differs in the two gaits (i.e., initiated atmidstance in walking vs. heelstrike whenrunning). During running the mass of thearms appears to be coupled to the cranio-cervical complex through the superiortrapezii and the associated nuchal ligament.Indeed, the combined kinematic, kinetic, andelectromyographic profiles suggest a bio-mechanical model in which the momentumof the runnerís arms is used to counteractthe tendency of the head and neck to pitchforward at each footstrike. The same, gait-specific, mechanical linkage may also helpto reduce impulsive loading of the headwhen running (as compared to fast walk-ing). Analyses of occipital morphology inRecent and fossil crania suggest that thisnovel mechanism, in which the nuchal liga-ment is a key player, may be unique amonghominoids to the genus Homo, thus provid-ing evidence of specialization for runninglate in human evolution.

P2.33BRANTLEY, S.*, HILL, P.S.M., Univer-sity of Tulsa, OK. Lekking in Gryllotalpa ma-jor, the prairie mole cricket: a test of the“hotshot hypothesis.”

Gryllotalpa major is a rare, burrowing in-sect indigenous to the tallgrass prairie of thesouth-central United States that is known tolek during mating. This study looked at pos-

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sible reasons for the lekking behavior in thisspecies. The “hotshot hypothesis” states thatmales congregate around a male that hascertain traits that make him more preferredby females during mate selection. In aggre-gating around the favored male, other malesincrease their own chances of mating. Dur-ing the mating season, prairie mole cricketmales build specialized burrows from whichthey project their mating call into the air. Fe-males flying in the area hear the mating callsand drop to ground level, entering the bur-rows of males of their choice. Since a male’scall is the only thing a female can use inselecting a mate, different aspects of themale’s mating song were analyzed in orderto pinpoint a preferred trait. One trait thatattracted other males to congregate arounda “hotshot” male was the amplitude of amale’s call. It was observed that males withthe loudest call on a particular night wouldentice other males to their positions to con-struct their own burrows the following nightor the next night that calling occurred. Thesedata support the “hotshot hypothesis” as thereason for lekking in Gryllotalpa major.

S9.14BREUNER, C. W.*, HAHN, T. P., Ari-zona State University, University of AlaskaFairbanks. Corticosterone and inclementweather: mechanisms underlying adaptivebehavioral responses in mountain birds.

In seasonally-breeding migratory birds,the drive to arrive early and establish a terri-tory on the breeding grounds carries with itthe potential benefit of improved reproduc-tive success, but also the risk of encounter-ing potentially life-threatening inclementweather. This is particularly true in speciesbreeding at high elevations or high latitudes.Storms can reduce food availability, limit for-aging opportunities, and impose increasedthermoregulatory costs. Individuals’ repro-ductive success can thus depend on howeffectively they assess risks, and then modifybehavior. In the High Sierra of California,mountain white-crowned sparrows(Zonotrichia leucophrys oriantha) typicallyreach sub-alpine breeding areas in earlyMay, when storms are common. Over thepast 6 years, we have shown that when stormconditions become extreme, Z. l. oriantha

typically abandon their territories and fly sev-eral kilometers to lower elevation, where con-ditions are milder and food is more abun-dant. Variation in internal reserves and/orfood availability at the breeding site maymodify the timing and duration of territoryabandonment. We have evidence that cor-ticosterone acts as an endocrine mediatorbetween the environment and behavior dur-ing inclement weather. This system is prov-ing ideal for studying the endocrine mecha-nisms that coordinate dramatic shifts in be-havior in response to both external and in-ternal factors. We have developed a work-ing model of how several of these factors(weather, food availability, energy reserves,and corticosterone) interact to affect behav-ioral decisions.

S10.5BREZNAK, J.A., Michigan State Uni-versity, E. Lansing. Phylogenetic diversityand physiology of termite gut spirochetes.

Spirochetes are major members of thetermite gut microbiota, accounting for up to50% of all the prokaryotes present. However,our understanding of them has been mea-ger, as none had ever been isolated in pureculture since first being observed in termiteguts over a century ago. By analyzing SSUrDNA clones (obtained after PCR amplifica-tion from termite gut DNA), we and othershave found that termite gut spirochetes rep-resent novel treponemes. As many as 26new and different species of Treponemawere detected in guts of various individualtermite species, implying that earth's termitesconstitute a rich reservoir of novel spirochetaldiversity. Physiological properties that en-able spirochetes to assume such abun-dance in termite guts are not yet clear, butprobable roles for spirochetes in termite nu-trition are now beginning to emerge fromstudies of the first pure cultures recently iso-lated in our laboratory [J. R. Leadbetter et al.(1999) Science 283:686-689]. All strains ob-tained so far produce acetate as a majorfermentation product, with some capable ofdoing so from H2 + CO2. This latter process,previously unknown in spirochetes, is a sig-nificant H2 "sink" and source of acetate intermite hindguts. In addition, all strains pos-sessed at least two homologues of nifH in

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their genomic DNA and catalyzed N2 fixa-tion, another process heretofore unknownin spirochetes. Microbially-produced acetateis known to be a major carbon and energysource for termites, and N2 fixation by gutmicrobes can supply up to 60% of the N re-quirement of some termite species. Hence,with the discovery of acetogenesis and N2

fixation by termite gut spirochetes, we arefinally beginning to reconcile the old obser-vation that elimination of spirochetes fromthe gut results in decreased survival of ter-mites.

S8.5 BROCHU, C. A., Field Museum. Be-yond mere morphology: reflections of a com-puted tomography addict.

Computed tomographic (CT) technologyhas become a standard method fornondestructively accessing the interior struc-tures of irreplaceable fossils. This vastly in-creases the informative power of fossils andallows researchers a unique opportunity tovisualize internal features in three dimen-sions, either through three-dimensional re-construction or as animations of sequentialslices. Either mode (2-D or 3-D) can bringnew insight into the study of fossil organismmorphology, whether the focus isphylogenetics, functional morphology, physi-ology, or any other research program. Thereare additional practical applications of CTimagery to fossil preparation and the tracingof post-collection human modification. CTimagery improves the researcher’s ability toillustrate complex internal structures, bothto the research community and the generalpublic. The data can be published in its na-tive digital format, either over the World WideWeb or through media such as CD-ROM orDVD, effectively allowing the disseminationof “virtual specimens”. Simple software ap-plications allow colleagues, teachers, andstudents to interact with the data. Digitalanatomical atlases can be generated for abroad diversity of taxa, which gives instruc-tors and students a larger sample of avail-able study specimens. One such atlas hasalready been made available for Alligatormississippiensis. Application of CT imag-ery to popularly-known taxa, as was recentlydone with Tyrannosaurus rex, gives re-

searchers a new means of making impor-tant morphological and evolutionary pointsto the general public. Nonavian dinosaursare inherently interesting to people, and ahost of evolutionary questions, from theanatomy of pneumatic structures in the skullto origin of birds, can be addressed througha combination of careful phylogenetic analy-sis and CT imagery. This lets scientists high-light principles common to all comparativebiologists to the public.

63.2 BRODIE, R.J., Smithsonian MarineStation at Fort Pierce. Ontogenetic changesin rates of water loss and shell-wearing be-haviors enable land hermit crab megalopaeto avoid desiccating in air.

The land hermit crab, Coenobitacompressus , migrates from sea to land dur-ing the megalopal stage of postlarval devel-opment. As the megalopa emerges ontoland, it encounters a physical environmentwholly different from that of the sea. I investi-gated changes in C. compressusí behaviorand physiology that enable it to avoid desic-cation on land. In one experiment, I exam-ined changes in rates of water loss before,during, and after megalopae were able tosettle on land to determine if their resistanceto desiccation improved over time. I foundthat megalopae became increasingly resis-tant to desiccation with age. In the secondexperiment, I exposed megalopae with andwithout snail shells to relative humidities of100, 92, 85, and 76 % to determine if theshell would increase survival in the lowerhumidity environments. Megalopae wearingshells were far more likely to survive the twolowest humidities compared to their nakedcounterparts. Thus, behavioral and morpho-logical enhancements to desiccation resis-tance facilitate the land hermit crabís transi-tion to land.

S1.5 BROWNELL, P.H.*, VAN HEMMEN,J.L, Oregon State University, Corvallis, Tech-nical University, Munich. Vibration sensitiv-ity and prey-localizing behavior of sand scor-pions.

As burrowing, nocturnal predators ofsmall arthropods, sand scorpions haveevolved exquisite sensitivity to vibrational in-

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formation that comes to them through thesubstrate they live on -dry sand. Over dis-tances of a few decimeters, sand conductslow velocity (~50 m/sec) surface (Rayleigh)waves of sufficient amplitude and bandwidth(fmax ~350 Hz) to be biologically detectable.Eight acceleration-sensitive receptors (slitsensilla) at the tips of the scorpion’s circu-larly arranged legs detect surface vibrationsgenerated by prey movements or ‘juddering’signals from other scorpions. From this in-put alone, target direction is accurately cal-culated up to 20 cm distance. By ablatingslit sensilla in various combinations on theeight legs, the contribution each makes incomputing target location can be assessed.Other behavioral experiments show that dif-ferential timing of surface wave arrival ateach sensor, and not relative amplitude ofstimulation, is the cue that determines targetlocation. A computational theory to accountfor wave source localization has been de-veloped using a population of second-or-der neurons, each receiving excitatory inputfrom one sensor and inhibition from a triadof sensors opposite to it in a circular, eight-element array. Input from a passing surfacewave opens a time window whose width de-termines the firing probability of second-or-der neurons. Stochastic resonance (optimi-zation) tunes the relative strengths of excita-tory and inhibitory inputs to second-orderneurons, and target direction is encoded asthe relative excitation of cells within the popu-lation. The excellent agreement betweentheory and behavioral observations confirmsthe mechanistic simplicity of the sandscorpion’s sensory system for computationalmapping of vibration source location.

S10.9BRUNS, T.D.*, BIDARTONDO, M.I.,TAYLOR, D.L., University California, Berke-ley. Interactions of ectomycorrhizal fungi andectomycorrhizal epiparasites.

We have studied non-photosyntheticplants in the Monotropoideae andOrchidaceae that obtain their fixed carbonfrom surrounding photosynthetic plantsthrough shared ectomycorrhizal fungi. These“epiparasites” are only indirectly connectedto surrounding trees, which are the ultimatesource of their carbon; their proximal hosts

are fungi that are mutualistically associatedwith the trees. We found that all epiparasiticplants have specific fungal associations,which in somecases exhibit geographic mo-saic patterns. In two species, Sarcodessanguinea and Pterospora andromedea,seed germination is stimulated by diffusiblecompounds from the fungi associated withthe adult plants, but not by distantly relatedfungi. Thus, the first step in establishment ofthese specific interactions is based on a spe-cific plant reaction to the presence of its fun-gal host. This fact, coupled with localizedseed dispersal, has parallels with insecthost-fidelity systems and may facilitate host-race formation, which we now have evidencefor in Corallorhiza species. In nature, S.sanguinea appears to increase the presenceof its host fungus, Rhizopogon ellenae, andthe abundance of Abies magnificaroots towhich the latter is associated. This eitherprovides an unusual case of parasite-in-duced host-hypertrophy, or alternatively itsuggests an unexpected mutualistic aspectto this symbiosis.

S2.4 BRYANT, S.V., University of California.Regeneration: something old; somethingnew.

Urodeles are unique among verte-brates in their ability to regenerate lost ap-pendages as adults. Evidence from numer-ous studies indicates that regeneration isa biphasic process, with the first phaseinvolving the transition to a blastema, andthe second involving the control of growthand pattern formation within the regenera-tion blastema. Patterns of gene expressionin the first phase mark it as unique anddistinct from limb development. In the sec-ond phase, patterns of gene expressionand tests of gene function, suggest mecha-nisms that are common to both develop-ment and regeneration. It is the genes ex-pressed during the early, unique phasethat transform differentiated limb cells intoa blastema with similar properties to thatof an embryonic limb bud, thereby makingregeneration possible. Recent advancesin somatic cell transgenesis in the axolotlare allowing for the functional analysis ofthe molecules controlling the transition

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into dedifferentiation, and will eventuallylead to therapeutic interventions to stimu-late human regeneration.

53.4 BUCHANAN, J. S.*, CRANFORD, J. A.,Colorado State University, Fort Collins, Vir-ginia Polytechnic Institute and State Univer-sity. Changes in energy utilization, food pro-cessing, and gastrointestinal morphology ofvoles under differing environmental condi-tions.

Meadow voles (Microtus penn-sylvanicus) are small herbivores that areactive year-round, yet have no capacityfor torpor. Their food supply, though abun-dant, may be of low quality when plantsundergo winter senescence. Therefore,they must adjust their food intake rate and/or modify their gastrointestinal morphol-ogy in order to obtain the energy neces-sary to meet increased demands duringwinter. We performed an experiment offactorial design, consisting of 112 meadowvoles, each assigned to one of eight trials,placed under the conditions of high (50%NDF) or low (5% NDF) dietary fiber, high(21 C) or low (5 C) temperature, and long(16L:8D) or short (8L:16D) photoperiod todetermine which of these environmentalvariables was most responsible for elicit-ing the behavioral or morphologicalchanges required for meadow voles tosurvive the winter. Meadow voles in-creased food intake and decreased di-etary turnover time under the most de-manding environmental conditions. Con-sequently, they were able to compensatefor their increased energy demands byincreasing food intake and decreasing di-etary turnover time, and made only mini-mal changes to their gastrointestinal mor-phology. Dietary fiber level was the mostimportant factor in eliciting these changesin intake rate, followed by ambient tem-perature and daylength, respectively.There were significant interactions be-tween the three factors and all play animportant role in bringing about thechanges necessary for meadow voles toendureharsh winter conditions.

S14.8BUCHHOLZ, D.*, HAYES, T., NIH, Uni-versity of California, Berkeley. Evolution ofdiversity in anuran tadpoles: acceleratedmetamorphosis in spadefoot toads.

Spadefoot toads exhibit a large diversityin larval period and size at metamorphosis.We used growth and development data toexamine evolutionary, physiological, andmorphological aspects of this diversity. Toobtain comparable data across taxa, wereared tadpoles under laboratory conditionsfrom all spadefoot toads and one parsleyfrog. Differences in growth and developmentsuggested physiology, rather than pheno-typic plasticity, explained larval period diver-sity. Mapping larval data onto a molecularphylogeny indicated that rapid metamorpho-sis originated within the spadefoot toad fam-ily. To understand the physiological basis foraccelerated metamorphosis, we used radio-immunoassay to estimate thyroid hormonelevels throughout prometamorphosis andclimax in Scaphiopus couchii, Speamultiplicata, and Pelobates syriacus. We alsoused an in vitro tail tip assay to measuretissue sensitivity to thyroid hormone. Thehigher thyroid hormone levels and the highersensitivity of the tail in vitro in Sc. couchiicorrelated with its shorter larval period length.We examined the relationship between lar-val period length and gonad, spade, andthyroid develoement. Gonads and spadesdifferentiated earlier in stage in Pelobatescompared to Spea and Scaphiopus. In con-trast, thyroid gland differentiation correlatedwith larval size rather than larval periodlength. In conclusion, the differences in thy-roid physiology across taxa may be endo-crinological mechanisms underlying accel-erated metamorphosis. Also, because mor-phological development during metamor-phosis is affected by thyoid hormone, physi-ological evolution to shorten larval period inNew World spadefoot toads may have hadheterochronic side-effects in spadefoot de-velopment.

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P3.107 BUCK, C.L.*, BARNES, B.M., Uni-versity of South Dakota, University of AlaskaFairbanks. Influence of staged encounterson testosterone and corticosterone in free-living arctic ground squirrels.

In a field study on the North Slope ofAlaska we determined levels of plasma tes-tosterone and corticosterone for male arcticground squirrels after emergence from hi-bernation in spring, throughout the matingseason, and prior to their immergence intohibernation in late summer. In mid April re-productively active males emerged with tes-tes descended into the scrotum and with in-termediate levels of plasma testosterone.Testosterone levels remained constant at 2.9± 0.29 ng/ml for about 1 week before signifi-cantly increasing to the active season maxi-mum of 4.6 ± 0.42 ng/ml. A lesser peak inlate summer of 2.7 ± 0.17 ng/ml not associ-ated with testicular maturation was observedbefore levels decreased to the annual mini-mum of 1.7 ± 0.57 ng/ml prior to entrance tohibernation. Corticosterone levels did notvary significantly across season and aver-aged 4.3 ± 0.10 ng/ml. We tested the respon-siveness of plasma testosterone and corti-costerone to challenges by conspecificmales by staging aggressive encounters be-tween males and comparing plasma levelsof these animals to those of unmanipulatedanimals. The effect of staged encounters ontestosterone level depended on time of year.Testosterone levels in spring were signifi-cantly up-modulated after a staged encoun-ter and were positively correlated to the rela-tive intensity of the encounter, whereasstaged encounters in late summer had nosignificant effect on testosterone level. Cor-ticosterone levels in both spring and latesummer were significantly increased bystaged encounters and were positively cor-related to the relative intensity of the encoun-ter. These results suggest that circulating lev-els of testosterone and corticosterone inmale arctic ground squirrels are the result ofa combination of seasonal and social fac-tors.

S13.10 BUCKLEY, D.P., Quinnipiac Univer-sity, Hamden CT. Fostering learning-cen-tered experiences with web-based technol-ogy.

The scientific literacy of our nation is aconcern, but emerging insights about thecognitive development of learning and neweducational technologies provide encour-agement that we may be engaged in a peda-gogical revolution. However, technology isno panacea. Exploiting the learning poten-tial of the web will require the promotion ofinquiry-oriented and learning-centered prin-ciples, but most web sites are little more thanelectronic books, with little interactivity andless assessment. Interactivity can promoteactive learning styles. Assessment tools canprovide real-time feedback, incentive sys-tems to facilitate competency-based learn-ing standards, and diagnostic clues aboutindividual learning needs. Learning-cen-tered technology that is beginning to emergemay help us to grapple with one of the worstobstacles to teaching reform: the CoverageDilemma. Many faculty are wary to spendvaluable class time on time-intensivepedagogies. Assessment-rich, web-basedinstructional technology may allow us tomove the authority of learning foundationalinformation to our students on their own time,making room for more important learninggoals in class time. The most exciting appli-cations of web-technology may be those thatfoster student experience in the process ofscience with research simulations or throughaccess to online data and research tools.However, these more open-ended learningexperiences tend to be more leaky peda-gogically; not all students are prepared tobenefit from these more demanding experi-ences. Therefore, depending on the sophis-tication of the students, there may be a needfor new instructional designs that provideassessment in new ways in these more de-manding, open-ended learning environ-ments. Lastly, we must develop web-basedtechnology that promotes these science edu-cation standards for all students, not just forour majors.

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P1.47BUDD, S.J.*, ROER, R.D., KINSEY,S.T., University of N.C. at Wilmington. Ener-getic cost of osmoregulation as a function ofsize and salinity in Callinectes sapidus.

In order to determine the energetic costof osmoregulation in C. sapidus over a rangeof salinities, adult and juvenile crabs wereacclimated to either sea water (1000 mOsm)or dilute sea water (150 mOsm). Oxygenuptake was measured in vivo with intactcrabs and in vitro using gills removed fromthe crab and ligated at the proximal end.Data demonstrated that at each salinity therewas a decrease in weight-specific oxygenuptake with increasing body mass and gillmass. Acclimation to dilute medium resultedin an increase in whole-animal oxygen up-take for crabs of all weights relative to that insea water. Exposure of sea water-accli-mated posterior gills to 150 mOsm resultedin a rapid and marked increase in oxygenuptake relative to sea water. Nuclear mag-netic resonance spectroscopy on individualgills was able to resolve the relative con-centrations of all the major phosphate com-pounds involved in energy metabolism (argi-nine phosphate, ATP and inorganic phos-phate). Exposure of sea water-acclimatedposterior gills to 150 mOsm resulted in amarked decrease in arginine phosphate andan increase in inorganic phosphate.

P2.46BUDICK, S.B.*, O’MALLEY, D.M.,Northeastern University Minimal behavioraldeficits are observed after laser-ablation ofthe nMLF in larval zebrafish.

Larval zebrafish exhibit a range of loco-motive behaviors including swimming, turn-ing and escaping. These behaviors are con-trolled by a relatively small group ofbrainstem neurons including cells of thenucleus MLF (nMLF) plus reticulospinal,vestibulospinal and T-reticular neurons. Littleis known of the function of the nMLF cells,though they constitute perhaps 15% of thetotal descending motor control system in lar-val zebrafish. The nMLF cells are suggestedto be involved in the initiation of swimming(Bernau et al. 1991; Uematsu and Todo,1997) and might constitute part of the mid-brain locomotor region. Because laser-ab-lation is a useful technique for revealing the

functional role of individually identified hind-brain neurons (Liu and Fetcho, 1999), weattempted to laser-ablate the nMLF both uni-laterally and bilaterally (a minimum of 7 cells/hemisphere), using a 15mW Kr-Ar laser.Larval behavior was then analyzed after arecovery period of at least 24 hours. Spon-taneous locomotion, as measured by thenumber of swim bouts and the total distanceswam over 30 minutes, was not effected byablation. Furthermore, kinematic analysis ofhigh-speed imaging data revealed no ma-jor deficits in either the escape-response orswimming. The data do suggest, howeverthat the nMLF may be important for generat-ing high angular velocity, large amplitudeescape responses. Occasionally, multiple,spontaneous C-bends occurred in rapid suc-cession. A striking feature of these C-bendswas that they resulted in little forward pro-pulsion. Such abnormal C-bends were notobserved in control fish. These results sug-gest that nMLF cells are not necessary forthe initiation/control of swimming, but maycontribute to the coordination or control ofthe escape response. Supported by NIHGrant NS 37789.

22.4 BUNDLE, M.W.*, DAIL, K.P., Univer-sity of Montana, Missoula. The metabolic costof flight in budgies: revisiting an outlier.

Measuring the metabolic cost of flight hasbeen possible for a little more than thirtyyears. Since V. A. Tucker’s classic work withbudgerigars, fewer than a dozen other spe-cies of birds have been flown in wind tun-nels in order to determine their metabolicrates during flight. Results from these stud-ies portray one of two patterns: either themetabolic cost of flight appears to be inde-pendent of flight speed, or the cost of flightappears as a U-shaped curve with increas-ing flight speed. All but Tucker’s study showlittle increase in metabolic cost across therange of speeds for which data were ob-tained. In addition to the evidence providedby metabolic data, recent measurements ofthe mechanical power developed duringflight also support the notion that birds areable to fly over a wide range of speeds withlittle change in the cost of flight. Flight costsin budgerigars should be viewed not as the

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commonly cited general rule, but rather asthe exception. Since Tucker’s work stands insuch stark contrast to nearly all of the avail-able data on flight costs, we have revisitedhis experiments in our tunnel, increasingboth the sample size and the range of speedsover which the birds have been flown. FourBudgerigars were flown across a range ofspeeds (4-16 m/s), while wearing a mask inorder to collect and analyze their expired air.Our measurements of the metabolic cost offlight agree well with those of Tucker’s budg-ies. This confirmation of the original pub-lished pattern suggests that budgies areunlike other species and are unable to du-plicate the unknown mechanism that allowsother birds to fly with costs that are indepen-dent of flight speed. (supported by NSF IBN-0082075)

18.5 BURNAFORD, J. L., Oregon StateUniversity. The physiology of positive inter-actions: effects of shade and season on en-dogenous levels of hsp70 in field popula-tions of the black chiton Katharina tunicata

Canopy-forming algae can be importantto consumers by providing food and protec-tion from predation or intense insolation. Inthe low rocky intertidal zone of the PacificNorthwest, the chiton Katharina tunicata isclosely associated with the canopy-formingalga Hedophyllum sessile. In previous stud-ies, Hedophyllum canopy removal resultedin a dramatic drop in Katharina abundances,but the cause of this decline was not deter-mined. In a three-year field experiment,Katharina numbers were significantly higherin shaded plots (artificial shade or naturalHedophyllum) than in unshaded plots in thespring and summer, but abundances werenot different in the fall and winter. Duringlow tide on sunny summer days, Katharinabody temperatures are 6 to 9oC warmer inthe open than in the shade. These data sug-gest that the shade provided by the algalcanopy is important for reducing heat stressfor Katharina. To examine the effect of shadeon the physiological state of chitons in thefield, I used fences to maintain Katharinaunder shaded and unshaded conditionsfrom April to November of 1999 and April toAugust of 2000. From monthly tissue

samples of these chitons, I quantified en-dogenous levels of heat shock proteins(hsp70 isoforms). To examine the effect ofseasonal ambient temperature on hsp70levels, I also collected monthly tissuesamples from the unmanipulated Katharinafield population from April 1999 to August2000. These data on seasonal and shade-related variations in the heat-shock re-sponse of Katharina, combined with datafrom a long-term ecological study, give aunique picture of the interacting effects ofphysiology and ecology on community struc-ture.

P1.61A BURNESS, G.P.*, YDENBERG,R.C., HOCHACHKA, P.W., University of Cali-fornia, Los Angeles, Simon Fraser Univer-sity, University of British Columbia. Physi-ological origin and reproductive conse-quence of variation in daily energy expendi-ture: a study of breeding tree swallows.

We studied tree swallows (Tachycinetabicolor) provisioning dependent young to testfor relationships among parental daily en-ergy expenditure (DEE), the masses of in-ternal organs/tissues, and indices of breed-ing success. We predicted: (1) parental DEEwould increase with brood size and nestlingcondition, and (2) adults with high DEE wouldrequire large internal organs and high meta-bolic capacities in their pectoral muscles. Wemeasured the growth rate of nestlings fromnatural broods of 5, 6 and 7 over a 4-dayperiod, followed by parental DEE using thedoubly labeled water technique. Adults werethen dissected and internal organs wereweighed. As an index of capacity for fluxthrough specific steps in various metabolicpathways, we measured the activity of cit-rate synthase, pyruvate kinase, HOAD, andlactate dehydrogenase in the pectoralmuscle. The growth rate of nestlings wasindependent of the brood size in which theywere reared. This indicated that adults didnot trade-off nestling quality for quantity.Despite predictions, parental DEE was alsoindependent of brood size. We hypothesizethat adults differed in foraging efficiency andmatched their clutch size to their own indi-vidual provisioning abilities. Among individu-als with the same sized broods, in one of

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two years there was a positive relationshipbetween DEE and brood mass, suggestingreproductive benefits of an high DEE. Therewas no relationship between an individual’sDEE and the size of any internal organ orthe metabolic capacity of the pectoralmuscle. Consequently, a previous sugges-tion that large internal organs allow for themaintenance of high-energy budgets is notsupported.

P1.28BURNETT, K., ILIFF, S., BURNETT, L.*,University of Charleston, SC. Chronic sub-lethal hypoxia increases susceptibility ofLitopenaeus vannamei to bacterial chal-lenge.

Mortality rates of the aquacultured shrimpLitopenaeus vannamei injected with Vibrioparahaemolyticus are significantly in-creased when the bacterial challenge isaccompanied by an immediate shift fromwell-aerated water to sub-lethal hypoxia(acute hypoxia). A more realistic scenario isthat shrimp raised in intensive culture or innatural ecosystems would be exposed forlonger periods of time to sub-lethal hypoxia(chronic hypoxia). The present study ad-dressed the possibility that animals mightadapt to chronic hypoxia, returning to a moredisease- resistant status. Juvenile L.vannamei (1.0 - 1.5 g) were either main-tained under normoxia or exposed to sub-lethal hypoxia (4% O2, 2% CO2 and pH of6.8-7.0). After seven days animals from bothexposure conditions were injected intramus-cularly with an LD50 dose (105/shrimp) of V.parahaemolyticus. Both test groups wereheld under sub-lethal hypoxia for 48 hoursand monitored for survival. Mortality rateswere compared by a repeated measurestwo-way ANOVA. Chronic (7 day) hypoxiasignificantly increased mortality rates in chal-lenged shrimp compared to acute hypoxia.Taken together with our previous studies(Mikulski et al., [2000] J. Shellfish Res. 19:301-311), these data show that both acute andchronic hypoxia increased susceptibility ofL. vannamei to bacterial challenge. Further-more, these shrimp did not successfullyadapt to overcome the suppressive effectsof hypoxia on disease resistance, rather the

animals displayed higher mortality rates withincreased time of exposure to hypoxia.(USDA CSREES 99-35204-8555)

P3.1 CAPPOLA, V.A., FAUTIN, D.G.*, Univer-sity of Kansas. The status of Corallimorpharia(Cnidaria, Anthozoa) based on molecular datafrom mitochrondrial 16s rDNA and nuclear 28sDNA.

Corall imorpharia is an order ofAnthozoa (phylum Cnidaria) that is cur-rently considered equivalent in rank toScleractinia (hard corals) and Actiniaria(sea anemones). Rather than being anindependent order, Corallimorpharia hasbeen hypothesized to be part ofScleractinia or Actiniaria. Morphologicalevidence supports corallimorpharians asmore closely related to scleractinians.Published sequence data for mitochon-drial 16S rDNA and nuclear 18S rDNAsupport the position of corallimorpharianswithin the scleractinian clade, but data fromnuclear 28S rDNA support them beingmore closely related to actiniarians. Dif-ferences in taxon sampling and methodsof analysis, and small sample sizes havecontributed to problems with comparingamong molecular analyses. We se-quenced the nuclear 28S ribosomal RNAgene and the mitochondrial 16S riboso-mal gene from representatives from mosthexacorallian orders. Our preliminary par-simony analyses do not support acorallimorpharian clade. This research wassupported by NSF grant DEB95-21819(PEET) to DGF.

61.4 CARD, G.*, WEYAND, P., BIEWENER,A.A., Concord Field Station, Harvard Uni-versity, Bedford. Changes in effective me-chanical advantage of the human limb dur-ing sprint acceleration.

How do people go fast? Previous stud-ies have examined the role of leg muscleforce in relation to energy cost during run-ning at various steady speeds, but few haveaddressed how the leg muscles contributeto accelerating the body to attain thosespeeds. We examined humans sprintingfrom a crouch to top speed. Using a runwaywith an imbedded force plate and synchro-

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nized video data, we were able to determinethe effective mechanical advantage (EMA)of the limb at different steps of each subject’ssprint acceleration to top speed. EMA isdefined as the ratio of limb muscle force toground reaction force integrated over thetime of limb contact with the ground. It wasmeasured at each of the leg joints (hip, knee,ankle) and then averaged for an overallmeasure. Data from the nine runners mea-sured indicate that, as opposed to steadystate running in which EMA does not changewith speed, EMA increases slightly as thesubject increases speed by accelerating inthe first several steps of a sprint. EMA distri-bution between joints also changes duringacceleration, with hip EMA starting low andincreasing while knee EMA starts high anddecreases. These results imply that duringrapid acceleration, more of the force is sup-plied by hip extensor muscles whereas dur-ing steady state running, these muscles havediminished importance and supporting forceis generated more by knee extensors. Un-derstanding muscle mechanics during ac-celeration thus has implications for fiber typedistribution at different joints and for betterquantifying the mechanics and energeticsof free-ranging animals who rarely move ata steady rate.

27.3 CARELLO, C. A.*, SCHEUNMANN, T.L., HEITMANN, D. M., University of Wiscon-sin-Eau Claire. How body size affects themetabolic efficiency and lower limb joint ki-nematics of quail running on an incline.

The majority of studies dealing with bi-pedal locomotion on varying surface gradeshave focused on humans. Thus, little is knownabout the relationship between body massand efficiency of locomotion for running oninclines in non-human bipeds. In order toquantify this relationship in quail we usedoxygen consumption analysis to determinethe efficiency of incline running in small But-ton Quail (43g) and large Mountain Quail(211g). We found that Mountain Quail weremetabolically more efficient than ButtonQuail when running uphill. In an attempt toexplain the mechanisms responsible for thisrelationship between body mass and effi-ciency, we then conducted kinematic analy-

sis on the hip, knee and ankle joints for leveland incline running. We found that the rangeof motion for extension of all lower limb jointsincreased on an incline. We also found thatthere was a relatively greater increase inthe extension of the limb joints in the smallerButton Quail when compared to the largerMountain Quail. Extension of the lower limbjoints occurs during the acceleration phaseof the step and this is therefore consideredthe energetically costly phase of the step.Thus, smaller animals incur a reduction inmetabolic efficiency because their lower limbjoints must undergo a greater range of mo-tion during the most energetically expensivephase of the step.

45.2 CARL, T. F., HANKEN, J.*, HarvardUniversity, Cambridge, MA. Neural-crestderivation of the ossified skull in amphib-ians revealed by vital labeling with GFP.

Derivation of most if not all of the ossifiedskull from the embryonic neural crest is anaccepted axiom of contemporary develop-mental biology. Yet, this “fact” is based ondirect empirical results involving just onespecies of vertebrate, the domestic chicken.Anuran amphibians (frogs) pose a particu-larly difficult challenge in this regard: bonetypically forms many weeks after hatching,and tracing individual cells over this lengthyinterval is technically difficult. We used RNAencoding for green fluorescent protein (GFP)to label premigratory neural crest in embryosof Xenopus laevis, and assessed cranial de-rivatives both before and after metamorpho-sis. Results confirm the neural crest contri-bution to larval cranial cartilages demon-strated previously by using conventional vi-tal stains, lineage markers, and ablation tech-niques. They also provide evidence for theneural crest derivation of a major paired skullbone, the frontoparietal; other, later-formingbones are currently under study. This is thefirst direct empirical demonstration of neuralcrest contribution to the ossified skull in anyamphibian. Supported by NSF.

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44.4 CARL, T.F.*, KLYMKOWSKY, M.W.,HANKEN, J., Harvard University, Cambridge,MA, University of Colorado, Boulder, HarvardUniversity, Cambridge, MA. Multiple func-tions for the gene slug in Xenopus laevis.

The neural crest is a distinct populationof embryonic cells found only in craniates.Several genes, including BMP-4and thezinc-finger transcription factor Slug, havebeen shown to mediate neural crest devel-opment in both chickens and mice. We ex-amined the function of Slug in the frog Xeno-pus laevisby injecting antisense RNA (ASR)targeted to the 3' UTR of Xenopus Slug(XSlug). Injection of XSlug ASR inhibits neu-ral crest-cell migration and leads to reduc-tion or loss of many neural crest derivatives,including pigment cells and cranialcartilages. Moreover, regions injected withXSlug ASR show significantly elevated lev-els of cell death, and expanded regions ofthe BMP-4antagonist, Chordin. In additionto its important role in neural crestmigration,XSlugmay mediate the cell-death-signaling pathway and other significant de-velopmental pathways in Xenopus laevis.Supported by NSF.

S9.13CARR, J.A.*, BROWN, C.L.,MANSOURI, R., VENKATESAN, S., TexasTech University, Lubbock. Stress, neuropep-tides, and feeding behavior: an evolutionaryperspective.

Stress inhibits feeding behavior in allvertebrates. Data from mammals suggest animportant role for hypothalamic neuropep-tides, in particular the melanocortins andcorticotropin-releasing hormone (CRH), inmediating stress-induced anorexia. The ef-fects of CRH on food intake are evolution-arily ancient, as this peptide inhibits feedingin fishes, birds, and mammals. The effects ofmelanocortins on food intake have beenstudied only in mammals. Although there isevidence that CRH and the melanocortinsinfluence hypothalamic circuitry controllingfood intake, these peptides may have a moreprimitive role in modulating visuomotor path-ways involved in the recognition and acqui-sition of food. Stress rapidly reduces visu-ally-guided prey-catching behavior in toads,an effect that can be mimicked by adminis-

tration of CRH, while corticosterone and iso-proterenol are without effect. Melanocortinsalso reduce prey-oriented turning move-ments and, in addition, facilitate the acquisi-tion of habituation to a moving prey item.The effects of these neuropeptides are rapid,occurring within 30 min after administration.Thus, changes in neuroendocrine statusduring stress may dramatically influence theefficacy with which visual stimuli releasefeeding behavior. By modulating visuomotorprocessing these neuropeptides may helpanimals make appropriate behavioral deci-sions during stress. Supported in part by aHHMI grant through the Undergraduate Bio-logical Sciences Education Program to TTU.

21.4 CARRANO, M. T., SUNY at StonyBrook. Homology and the evolution of non-avian dinosaur locomotion.

Non-avian dinosaurs diversified through-out the Mesozoic from a single bipedal,parasagittal-limbed ancestor. Their 140-myradiation spanned over three orders of mag-nitude in body size and included eight ma-jor clades. In spite of this, diversificationwithin the dinosaurian locomotor apparatusappears to have been comparatively re-stricted. I analyzed dinosaur hind limb andpelvic anatomy within a cladistic frameworkin order to quantify these patterns of change.Using methods to analyze both discrete andcontinuous characters in a phylogeneticcontext, I identified where homoplasy con-stitutes parallelism and might thereby beused to infer similar selective pressures onhind limb function. Finally, I evaluated theresulting phylogenetic patterns in light of ter-restrial locomotor biomechanics. Theseanalyses revealed repeated, independentderivations of several morphological fea-tures that have potential relevance for hindlimb locomotor function. These include an-teroposterior expansion of the ilium, medialreorientation of the femoral head, and el-evation of the femoral lesser trochanter. Suchparallel changes appear to reflect the en-largement of several major hind limbmuscles, as well as a trend towards switch-ing their predominant function from abduc-tion-adduction to protraction-retraction. Thetiming of these changes suggests that they

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occurred subsequent to the initial diver-gence of Dinosauria into its constituent lin-eages. In addition, many “avian” character-istics are shared with more basal theropoddinosaurs, and several were acquiredconvergently in otherdinosaurian clades.

42.3 CARRE-O, C.A.*, NISHIKAWA, K.C.,Northern Arizona University, Flagstaff. Doesmorphology correlate with prey capture ki-nematics in leptodactylid frogs?

Leptodactylid frogs exhibit diversity of thetongue and jaw mechanics during prey cap-ture. Two mechanisms of prey capture havebeen seen in leptodactylids: inertial elonga-tion and mechanical pulling. Phylogeneticanalyses suggest that inertial elongation hasevolved independently from mechanicalpulling several times within leptodactylids.The goal of this study is to examine the evo-lution of feeding mechanisms in this diversegroup of frogs. Feeding mechanisms of frogscan be categorized based on patterns of ki-nematics. The primary kinematic differencebetween inertial elongation and mechani-cal pulling is the movements of the tongueand jaw. During inertial elongation, the move-ments of the tongue and jaw are preciselycoordinated, whereas in mechanical pull-ing, these movements are uncoupled.Leptodactylids that are considered to be in-ertial elongators tend to have short gapecycles (~11 ms), a high velocity of the lowerjaw during mouth opening, and a great in-crease in the length of the tongue (180% ofresting length). In contrast, leptodactylidfrogs that are defined as mechanical pullersgenerally have longer gape cycles (~28 ms),slower velocity of the lower jaw, and a de-crease in the length of the tongue duringprotraction (40% of resting length). Thus, weexpect to find relative differences in the le-ver system of the jaw between inertialelongators and mechanical pullers. Inertialelongators should have proportionallyshorter in-levers in order to maximize thespeed of mouth opening, while mechanicalpullers should have proportionally longer in-levers in order to maximize the force of mouthclosing. The variability in kinematics andmorphology among species of leptodactylidsmay reflect differences in the foraging ecol-ogy between species.

21.3 CARRIER, D.R.*, LEE, D.V., WALTER,R. M., University of Utah, Salt Lake City. Influ-ence of rotational inertia on the turning per-formance of theropod dinosaurs.

Turning agility of theropod dinosaursmay have been severely limited by the largerotational inertia of their horizontal trunks andtails. Bodies with mass distributed far fromthe axis of rotation have much greater rota-tional inertia than bodies with the same massdistributed close to the axis of rotation. Inthis study, we increased the rotational iner-tia of human subjects 4.6 times, to match ourestimate for theropods the size of humans,and measured the subjects’ ability to turn.To determine the torque required to executeturns, three subjects performed 45 degreejump turns on a force platform. When therotational inertia was increased 4.6-fold, thetime to push-off increased 1.8-fold and thetorque impulse applied to the ground in-creased 3.76-fold. To determine the effect ofthe increased rotational inertia on maximumturning capability, five subjects performedjump turns in which they jumped verticallyfrom a standing position and attempted tospin as far as possible before landing. Thistest resulted in a 4.9-fold decrease in theangle turned. We also tested the ability ofthree subjects to perform sharp running turnsin a tight slalom course of six 90 degree turns.When the subjects ran with the 4.6-foldgreater rotational inertia, the time to com-plete the course increased by 34 %. Hence,the results from these tests suggest that ro-tational inertia may have limited the turningperformance of theropods. Characters suchas retroverted pubes, reduced tail length,decreased body size, pneumatic vertebrae,and absence of teeth reduced rotational in-ertia in derived theropods and may haveimproved their turning agility. To reduce ro-tational inertia, theropods may have run withan arched back and tail, an S-curved neck,and forelimbs held backwards against thebody.

P2.85CARROLL, A.M.*, WAIN-WRGHT,P.C., University of California, Davis. Func-tional morphology of prey capture in the pal-lid sturgeon (Scaphirhynchus albus).

We examined the anatomical and ki-nematic basis of prey capture in sturgeon.

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Sturgeon (Acipenseridae) are a basalactinopterygians with a highly derived cra-nial morphology. Despite their anatomi-cal singularity and phylogenetic signifi-cance, no functional study of the kinemat-ics of sturgeon feeding has been pub-lished. Feeding pallid sturgeon(Scaphirhynchus albus) were filmed in lat-eral and ventral views at 250 frames persecond. Feeding events were character-ized by jaw opening, jaw protrusion, cau-dal-ventral retraction of the hyoid, ventralexpansion of the branchial basket, andadduction followed by abduction of theopercular margin. Prey items were drawninto open jaws which were closed afterprey entry, indicating that sturgeon feedby suction rather than biting. Evidence frommuscle stimulation and anatomy supportpreviously published hypotheses about themuscular basis of feeding kinematics. Thesturgeon’s jaws are not directly connectedto its neurocranium, but are suspendedfrom the hyoid arch and may be protrudedventrally. Protrusion is powered by the pro-tractor hyomandibularis muscle which ro-tates the hyomandibula rostrally at its ar-ticulation to the neurocranium. This ros-tral rotation is transmitted to the jaws, whichare deflected ventrally by the ventrallysloping underside of the neurocranium.This mechanism of jaw protrusion is uniqueto the order Acipenseriformes. The robuststernohyoideus drives hyoid retraction,jaw opening, and branchial basket expan-sion. Jaw opening by the sternohyoideusis the hypothesized ancestral jaw open-ing mechanism for actinopterygians. De-spite the morphological differences be-tween sturgeon and other lineages the ki-nematics of sturgeon feeding are essen-tially similar to other aquatic-feedinggnathostomes.

S9.12CARRUTH, L.L.*, JONES, R.E.,NORRIS, D.O., University of California at LosAngeles, University of Colorado, Boulder,University of Colorado, Boulder. Stress andPacific salmon: a new look at the role of cor-tisol in olfaction and home-stream migration.

Pacific salmon (genus Oncorhynchus)exhibit an interesting and uncommon life-

history pattern that combines semelparity,anadromy, and navigation (homing). Dur-ing smoltification, young salmon imprint onthe chemical composition of their natalstream water (the home-stream olfactorybouquet or “HSOB’); they then migrate to theocean where they spend a few years feed-ing prior to migrating back to their natal fresh-water stream to spawn. Upstream migrationis guided by the amazing ability to discrimi-nate between the chemical compositions ofdifferent stream waters and thus identify andtravel to their home-stream. Pacific salmondemonstrate marked somatic and neuraldegeneration changes during home-streammigration and at the spawning grounds. Theappearance of these pathologies is corre-lated with a marked elevation in plasma cor-tisol levels. While the mechanisms of salmo-nid homing are not completely understood,it is known that adult salmon continuouslyutilize two of their primary sensory systems,olfaction and vision, during homing. Olfac-tion is the primary sensory system involvedin freshwater homing and HSOB recogni-tion, and will be emphasized here. I havehypothesized that the increase in plasmacortisol during home-stream migration ofPacific salmon is adaptive because it en-hances the ability to recall the imprintedmemory of the HSOB. Elevated plasma con-centrations of cortisol could prime the hip-pocampus or other olfactory regions of thebrain to recall this memory and, therefore,aid in directing the fish to their natal stream.Thus, specific responses of salmon to stres-sors could enhance reproductive success.

P3.9A CARSTENS, B. C.*, LUNDRIGAN,B. L.; Michigan State University Museum andthe Departmen, Michigan State UniversityMuseum and the Departmen. A phylogenyof the American nectar-feeding bats(Chiroptera, Phyllostomidae) based on mor-phological characters.

There are forty-two recognized speciesof phyllostomid bats that feed primarily onnectar. As pollinators for more than threehundred species of plants the nectar-feed-ing members of the Phyllostomidae are animportant component of neo-tropical ecosys-tems. We present a phylogeny of thirty-eight

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species of nectar-feeding bats based on 119morphological characters. Our data supportthe Glossophaginae, Phyllonycterinae, andBrachyphyllinae as monophyletic clades,but suggest that nectar-feeding evolvedmultiple times within the Phyllostomidae. Ex-aminations of skull morphology suggest thatthere are different adaptations that can fa-cilitate the utilization of nectar as a resourcein phyllostomid bats.

6.1 CARTER, T.L.*, ERICKSON, L.B.,ELLIOTT, J.K., University of Puget Sound,Tacoma, WA. The influence of hybridizationon anemonefish evolution.

Anemonefishes (Genera:Amphiprion andPremnas; Family Pomacentridae) are agroup of 28 species of coral reef fishes thatare obligate symbionts of large tropical seaanemones. A recent molecular phylogeneticstudy of anemonefishes, based on data fromtwo mitochondrial genes (cyt b and 16S) forsix representative species, produced a phy-logeny that was significantly different from aprevious phylogeny based on morphologi-cal data. To further evaluate this difference,we have sequenced another mitochondrialgene (ND2) and a nuclear gene (Tmo-4C4)for 14 species of anemonefishes. The phy-logeny based on mitochondrial data wassignificantly different from the phylogenybased on nuclear data. Becausemitchondrial DNA is maternally inherited,phylogenies based on mitochondrial datacan be misleading if hybridization amongspecies has occurred. At least oneanemonefish species (Amphiprionleucokranos) is thought to be the result ofhybridization between two very differentanemonefish species (A. chrysopterus andA. sandaracinos). Both our mitochondrialand nuclear data provide molecular evi-dence for the hybrid origin of A. leucokranos.The nuclear data also indicate that otheranemonefish species may be the result ofpast hybridization events. This suggests thathybridization may have been important inanemonefish speciation and that reticulateevolution is a plausible explanation for thediversification patterns observed in thisgroup of coral reef fishes.

56.4 CASH, W.B.*, HOLBERTON, R.L.,Maryville College, University of Maine,Orono. Stress and the slider turtle.

We examined physiological and behav-ioral questions related to stress, locomotoractivity and dispersal movement in the sliderturtle, Trachemys scripta. Like many othervertebrates, slider turtles show a corticos-terone response to capture and handling,characterized by an increase in plasma cor-ticosterone concentration with handling time.In the laboratory, turtles implanted with ex-ogenous corticosterone showed a significantincrease in caged locomotor activity whencompared to control animals with empty im-plants. In the field, the effects of the simu-lated drying of a pond on the behavior of T.scripta were measured. Turtles respondedto the draining of a pond by the emigrationof the majority (75%) of the experimentalpopulation. Turtles had significantly elevatedcorticosterone when compared to individu-als captured in a control pond, where condi-tions were held constant. However, 25% ofthe experimental group did not emigrate fromthe pond, suggesting that there is naturalvariation in turtle populations when respond-ing to habitat declines, like rapidly decreas-ing quality or availability. Finally, aspects ofthe annual cycles of corticosterone werestudied in wild and laboratory-held sliderturtles. Male sliders were found to exhibitboth a change in baseline corticosterone andthe ability to respond to handling stressthroughout the period studied. Female slid-ers did not show a significant difference intheir baseline corticosterone concentrations,but did show a difference in their stress re-sponse over the sampling period. Theseresults show collectively that corticosteroneis involved with the ability of slider turtles torespond to environmental disturbances andcorticosterone may ultimately be the proxi-mate mechanism facilitating a stress avoid-ance response.

P2.90CASOTTI, G., West Chester Univer-sity. Microvilli within the lower intestine ofsparrows.

Tissue from the lower intestine of twospecies of sparrow, the house sparrowPasser domesticus and savannah sparrow

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Passerculus sandwichensis was sectionedin an unbiased manner and examined quan-titatively using stereology. The tissue wasprocessed for light microscopy, and scan-ning and transmission electron microscopyto examine the extent to which microvilli en-hanced the epithelial surface area of the rec-tum, coprodeum and cecae. Parametersmeasured included individual microvillussurface area, microvilli packing density andabsolute surface area. In both species, agreater surface area and packing density ofmicrovilli occurred within the rectum and thececae. Overall, the three measured variableswere not statistically significant betweenspecies at the 95% confidence level. In thececae, microvilli within the savannah spar-row had a higher individual surface area,packing density and absolute surface areathan in the house sparrow. The functionalimplications of a change in microvilli popu-lation are discussed in relation to retrogradeperistalsis within the lower intestine of birds.Funded by a Pennsylvania State System ofHigher Education Grant 2112-403.

P3.56CASTO, J.M.*, PARKER-RENGA, I.M.,KETTERSON, E.D., NOLAN, JR., V. IndianaUniversity, Bloomington. Experimentally el-evated testosterone in male dark-eyed jun-cos suppresses cell-mediated immune func-tion of social mates and offspring.

The immunocompetence handicap hy-pothesis (ICHH) predicts that testosterone-dependent secondary sexual signals that at-tract females also serve as honest indica-tors of male quality owing to testosterone’ssuppressive effect on immune function. Onlymales of high quality can express attractivetraits and resist disease despite suppressedimmunity. We have previously shown, aspredicted by the ICHH, that experimentalelevation of testosterone (T) in male dark-eyed juncos suppresses immunity and en-hances male attractiveness to females. Wehave also shown that T suppresses maleparental behavior and that females attemptto compensate for reduced male care by in-creasing their own parental effort. H e r ewe test whether the effects of treating maleswith T might extend beyond individual malesand indirectly influence immune function of

their social mates and offspring. We usedwing-web swelling in response to an anti-genic challenge as a test of cell-mediatedimmunity. We tested free-living females jun-cos that were mated to T-treated males (T-males) or controls (C-males), and tested off-spring of those matings. We found that im-mune responses were significantly sup-pressed in mates of T-males (41% lower) andtheir offspring (19% lower) as compared tothose of C-males. Combining these resultswith earlier findings, we suggest that thecosts to males of T-induced attractivenessmay go beyond immunosuppression. Re-ductions in T-nestling immunity may explaina previous finding that in juncos T-malesfledge significantly fewer young from theirnests than C-males. Additionally, the conse-quences for females of choosing males withtraits enhanced by T appear to be more com-plicated than previously thought.

P1.69CASTRILLO, L.A., LEE, R.E.* Jr., LEE,M., WAYMAN, J.A., Miami University, Oxford,OH, Miami University, Oxford. OH, MiamiUniversity, Oxford, OH, University of Wiscon-sin, Madison. Reduction of cold hardinessin overwintering Colorado potato beetles us-ing ice nucleating bacteria.

A key factor in the overwintering survivalof Colorado potato beetle (CPB) is the regu-lation of the temperature at which the insectfreezes. Like most overwintering insects,CPBs are unable to survive internal ice for-mation. Winter survival is enhanced by bothburrowing into the ground and by loweringtheir supercooling point, the temperature atwhich ice formation spontaneously occursin their body fluids. We have shown that thesupercooling capacity, a major factor in win-ter cold hardening of CPBs, can be regu-lated by exposure to ice nucleating active(INA) bacteria. Ingestion of INA Pseudomo-nas fluorescens immediately elevates thebeetle’s supercooling point. Furthermore,retention of the bacterium in burrowed CPBs’guts through winter increases their suscep-tibility to sub-zero temperatures. Reductionof the CPB’s cold hardiness using INA bac-teria offers a novel method for controllingthese beetles by targeting the overwinteringpopulation.

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3.2 CASTRO-SANTOS, T.*, HARO, A.,University of Massachusetts, Amherst, S.O.Conte Anadromous Fish Research Center,U.S. G. Optimal sprint speeds of fish travers-ing velocity barriers: further thoughts onburst-swimming data.

Migrating fish traversing velocity barriersare often forced to swim at speeds greaterthan Ucrit. Since prolonged and burst-swim-ming are powered by inefficient anaerobicmetabolic processes, models predictingoptimal swim speeds based on maximizedenergetic efficiency are inappropriate in thissituation. Instead of efficiency, fish need tomaximize distance of ascent, both to maxi-mize probability of success and to minimizethe number of ascent attempts with their as-sociated metabolic costs, recovery time, etc.From the standard fatigue-time equation (lnE= a + bU; E = endurance, U = swim speed),we show that there exists an optimal groundspeed for maximizing traversed distanceagainst any flow velocity greater than Ucrit,and this speed equals -1/b. Six migratoryfish species allowed to sprint volitionallyagainst fixed flow velocities of 1.5 - 4.5 m*s-

1 chose similar ground speeds regardlessof flow velocity, supporting the hypothesisthat sprinting speeds are modulated to maxi-mize distance of ascent.

58.2 CAVEY, M.J.*, WILKENS, J.L., Univer-sity of Calgary, Alberta, Canada. F-actin inthe amuscular arteries of the American lob-ster.

Seven vessels leave the heart of the lob-ster Homarus americanus: the unpaired an-terior median artery, sternal artery, and dor-sal abdominal artery and the paired anteriorlateral arteries and hepatic arteries. Superfi-cially, these arteries have a common, rela-tively-simple organization, consisting of anelastic lamina next to the lumen, a multilay-ered endothelium, and an enveloping ad-ventitia of collagen fibers. Patches of striatedmuscle cells occur in sectors of the dorsalabdominal artery. All of these arteries shouldserve as “capacitance” vessels, utilizing elas-tic elements to minimize the pulsatility ofhemolymph flow from the heart. It has beenproposed that lobster arteries, with the pos-sible exception of the dorsal abdominal ar-

tery, cannot contribute to the differential dis-tribution of hemolymph owing to the absenceof diameter-regulating muscle (and, hence,the inability to control their individual resis-tances). Comparative ultrastructural studieshave now revealed extensive networks ofcytoplasmic filaments in the endothelial cellsof the amuscular arteries. All vessels wereprepared in tandem for immunohistochem-istry for F-actin. They were slit lengthwise andopened onto microscope slides. The vascu-lar spreads were fixed with formaldehyde,permeabilized with Triton-X 100, and stainedwith rhodamine phalloidin. Both sarcomericmyofilaments in the muscle cells of the dor-sal abdominal artery and the aggregated fila-ments in the endothelial cells of the sixamuscular arteries stain positively for F-ac-tin. It thus appears that the muscular andamuscular arteries alike may have the prop-erties of “resistance” vessels, possessing thecontractile machinery by which to regulatetheir diameters and actively controlhemolymph flow.

53.1 C A V I E D E S - V I D A L , E . ,KARASOV,W.H.*, Universidad Nacional deSan Luis, Argentina, University of Wiscon-sin, Madison. Developmental changes in di-gestive enzymes of nestling house spar-rows, Passer domesticus.

Six decades of studies have speculatedthat digestive capacity might limit aviangrowth rate, or that developmental changesin the gut might determine developmentalchanges in digestive efficiency. However,there are no studies on digestive biochem-istry during avian development, except forstudies on mainly domestic birds that ex-hibit the precocial mode of development. Westudied pancreatic and intestinal enzymeactivities during development of a wild pas-serine bird exhibiting the altricial mode ofdevelopment. Wild nestling house sparrowswere studied immediately after removal fromthe nest (days 0, 3, 6 of age; day 0 = hatch),whereas captives were raised in the labora-tory beginning day 3 on a formulated casein/starch-based diet until fledging age (afterday 12). Digestive biochemistry was dy-namic. Tissue-specific activities of some di-gestive enzymes continued to increase

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through fledging, by >10 times in some cases(e.g., sucrase and maltase in mid-intestine).Total pancreatic amylase activity increased100 times between hatch and day 12through a combination of increases in tis-sue specific activity and pancreas mass.House sparrows differ from poultry, in whomafter about 2 weeks of age the specific activ-ity of intestinal and pancreatic digestive en-zymes is generally constant or declines dur-ing development. The data on intestinal andpancreatic enzymes help explain why diges-tive efficiency of nestling house sparrowsimproves with age, and the data seem con-sistent with the idea that digestive capacitymight limit feeding rate and hence growthrate. Supported by grants from FONCYT toECV, and NSF to WHK.

S12.6CHAMBERLIN, M.E., Ohio University,Athens. Developmental changes in insectepithelial ion transport and metabolism.

Like other caterpillars, the tobacco horn-worm (Manduca sexta) is essentially aneating machine that consumes largeamounts of food to fuel the growth and de-velopment of the subsequent two develop-mental stages. Commensurate with its hugeappetite is a large midgut, which is involvedin the digestion and absorption of food aswell as the transport of inorganic ions. Thelarval midgut, however, is destined to be de-stroyed and replaced by a pupal epithelium.Within the first two to three days of the fifthand final larval instar, there is a small in-crease hemolymph ecdysteroids. This smallincrease in ecdysteroids does not inducemolting, but does commit the insect to meta-morphosis. This commitment is manifestedon day 5 of the instar (wandering stage), asindicated by the appearance of a dorsal ves-sel and cessation of feeding. At the sametime midgut short-circuit current andtransepithelial potential decline 80% and49%, respectively. Mitochondrial metabolismis also altered upon the onset of wandering.Mitochondria isolated from the midguts ofday 5 larvae oxidize palmitoyl carnitine andsuccinate at rates that are 40% and 60% ofthe respective rates in mitochondria isolatedfrom day 4 larvae. In addition, the membranepotential is lower in mitochondria isolated

from the midguts of wandering larvae. Be-cause these physiological and metabolicchanges coincide with the onset of wander-ing, the midgut appears to modulated byecdysteroids. Furthermore, the changes inmidgut metabolism and ion transport occurabruptly, indicating that the larval midgut isdestroyed by programmed cell death, ratherthan by a gradual senescence of the tissue.

70.2 CHAN, S.-M., GU, P.-L., University ofHong Kong. The study of shrimp CHH/MIH/GIH gene family: gene structure, expressionand biological assay of recombinant neu-ropeptides.

The crustacean CHH/MIH/GIH neu-ropeptide family constitutes a group of im-portant hormone that regulates importantprocesses such as molting, glucose metabo-lism and reproduction. The characteriza-tion of these neuropeptides has attractedmuch attention due to their potential impor-tance in aquaculture. By RT-PCR and libraryscreening approach, we have isolated andcloned four cDNAs from the eyestalk of theshrimp Metapenaeus ensis. Two of thecDNAs encoded for proteins are homolo-gous to the CHH-subtypes and two of thecDNA encoded for proteins belong to theMIH/GIH subtypes. The organizations ofthese genes are very similar. They consist ofthree exons and two introns with conservedlocation of boundaries between the intron-exon. There are more than 20 CHH-Agenes, 5-6 CHH-B genes and 1-2 copies ofMIH and GIH gene in the shrimp genome.CHH-A, CHH-B, MIH- and GIH RNA tran-scripts can be detected in the eyestalk ofanimal at most stages. Only CHH-A and GIHtranscripts are detected in ventral nerve cord.Recombinant proteins for these neuropep-tides have been produced and used for bio-assay. Additionally, the recombinant proteinswere purified for antibody generation. Spe-cific antibodies against these recombinantproteins were generated and had beenused to detect these neuropeptides by im-munochemistry. Supported in part by a HKUinstitutional grant (CRCG) and the RGC ofthe HKSAR, China (HKU 7229/00M)

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P3.84CHAN, S.-M., GU, P.-L., University ofHong Kong. Molecular characterization of acDNA encoding for a shrimp cellular retinoicacid/retinol binding protein.

Members of the cellular retinoic acid bind-ing protein (CRABP) family are small pro-teins involved in the metabolic pathways ofretinoic acid (RA). Although there is reportdescribing the cloning of a retinoic-X recep-tor, no report describes the presence of RAin crustacean. To determine whether RA isalso involved in the regulation of develop-ment and whether CRABP is also involvedin the metabolism of RA in crustacean, weattempt to clone the CRABP cDNAs from theshrimp using a combination of RT-PCR andlibrary screening approach. Several identi-cal cDNA clones encoding the putativeMeCRABP were isolated. As confirmed byDNA sequence determination and RNANorthern blot analysis, the size of the CRABPmRNA is 0.9 kb. The cDNA is estimated toencode for a protein of 14 kDa. The size isclose to that of the retinoic/fatty acid bindingprotein reported in the vertebrate and inver-tebrate. MeCRABP is expressed abundantlyin the ovary and moderately in the eyestalk.Other tissues such as the muscles and testisalso express these genes. Recombinantprotein for the shrimp CRABP was producedin a pRSET bacteria expression system.Purified fusion protein was used to immu-nize rabbit to raise antibody. The fusion pro-tein binds to both retinoic acid (RA) and ret-inol (RO) with similar affinity. Anti-rCRABPrecognises cells of the eyestalk as well asmaturing oocytes of shrimp contain CRABP.Supported by HKU CRCG.

S4.4 CHANG, E.S., Bodega Marine Labo-ratory, University of California. Hormones inthe lives of crustaceans: an overview.

Decapod crustaceans have been a par-ticularly interesting and rewarding group ofanimals for the study of comparative endo-crinology. Most of the published studies,however, have dealt with the hormones ofthe adult stage; relatively few studies haveaddressed the hormones of the embryonicand larval stages. The most widely studiedhormones during crustacean ontogeny arethe arthropod molting hormones—the

ecdysteroids. Following a brief survey of crus-tacean endocrinology, I will present a se-lected review of what is known aboutecdysteroids in the various crustacean lifestages. The ecdysteroids are multifunctionaland are involved in a number of life pro-cesses (growth, regeneration, and repro-duction). I will also discuss aspects of theterpenoid hormone methyl farnesoate andthe crustacean hyperglycemic hormoneneuropeptide family during ontogeny.

P1.98CHANG, M.H*, CHEDIACK, J.G.,CAVIEDES-VIDAL, E., KARASOV, W.H., Uni-versity of Wisconsin, Madison, UniversityNacional de San Luis, Argentina, UniversityNacional de San Luis, Argentina, Universityof Wisconsin, Madison. Enhanced passiveabsorption in the presence of luminal nutri-ents in house sparrows.

We previously demonstrated in housesparrows substantial absorption in vivo of L-glucose, the stereoisomer of D-glucose thatdoes not interact with the intestine's D-glu-cose transporter. The mechanism, as firstproposed by Pappenheimer and coworkersin 1987, might be solvent drag throughparacellular spaces, activated by Na+-coupled nutrient transport. This hypothesispredicts that absorption of L-glucose mightbe highest when it is administered orally inthe presence of D-glucose and/or aminoacids. We tested this in two experimentswith house sparrows (Passer domesticus)using pharmacokinetic methods to measureabsorption. In Exp. 1, fractional absorptionof L-glucose (administered by oral gavageand measured by enzymatic method inplasma) in fed sparrows was higher (0.46 +-0.02, n = 7) than in sparrows fasted 12 h(0.40 +- 0.01, n = 6) (simple t-test T = -2.27, P= 0.044, DF= 11). The greater absorption wasapparently not due simply to longer reten-tion time of digesta, because no significantdifference was found for retention times. InExp. 2, fractional absorption of radiolabeledL-glucose was significantly higher when ad-ministered to fasted birds in solution with 200mM D-glucose (+ 80 mM NaCl) than whenadministered with 200 mM mannitol (+ 80mM NaCl) (respectively, 0.79 + 0.04 vs. 0.66+ 0.03; T= -2.47, P=0.035, DF= 9). In the

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former group, the absorption rateof L-glu-cose, determined by pharmacokinetic meth-ods, was 67% faster (P = 0.032). Our resultsare consistent with the solvent-drag hypoth-esis, and indicate that small, hydrophiliccompounds are absorbed faster and to agreater extent when there are nutrients (e.g.,sugar, amino acids) in the gut. Supported byFONCYT (01-03101) to ECV, and NSF IBN-9723793 toWHK.

P2.13CHARLESWORTH, T.D., LEHMAN,A.H.*, BLACKBURN, D.G., Trinity College,Hartford. Cytology and ultrastructure of theextraembryonic membranes of the quail,Coturnix coturnix.

In avian eggs, the yolk sac and chorioal-lantoic membrane (CAM) provide nutrientsand gas exchange for the developing em-bryo. Despite avian diversity, most of what isknown about anatomy and physiology ofthese extraembryonic membranes in birdscomes from studies on the domestic chicken.Quail tissues were harvested at Days 7 and14 following oviposition, and studied bymeans of transmission EM and light micros-copy of resin-embedded tissues. Chick tis-sues were sampled for comparison. At Day7, the yolk sac is trilaminar, consisting of athin monolayer of squamous epithelial cells,the vitelline capillaries, and the underlyingyolk endoderm. The endodermal cells arerich in mitochondria and phagocytosed yolkdroplets. Between the first and second weekof incubation, the CAM undergoes progres-sive expansion at the expense of the yolksac, and lines much of the inner surface ofthe eggshell with allantoic vessels. A thinsquamous epithelium overlies the allantoiccapillaries, providing a thin barrier to respi-ratory exchange. Tall intercalated cells withmicrovilli and abundant mitochondria spanthe CAM, extending towards the shell mem-brane. These cells have been implicated incalcium uptake in the chick by previous work-ers. Given that qualitative cytological differ-ences between the quail and chick were notobserved, our ongoing work is focusing onquantitative comparisons in abundance andontogeny of cell populations.

S4.3 CHARMANTIER, G., University ofMontpellier, France. Ontogeny of osmoregu-lation in crustaceans : the embryonic phase.

Three patterns of ontogeny of postem-bryonic osmoregulation have been recog-nized in crustaceans : (1) osmoregulationvaries little with development stage and theadults are weak regulators orosmoconformers; (2) the adult type of effi-cient osmoregulation is established in thefirst postembryonic stage; (3) metamorpho-sis marks the appearance of the adult typeof osmoregulation, generallyalong with theoccurrence of ion-transporting cells and Na-K ATPase in diverse organs. This review willconcentrate on the ontogeny of osmoregu-lation in embryos, particularly in species be-longing to type 2 : they are euryhaline andso are their hatchlings. Embryos are osmoti-cally protected against variations in environ-mental salinity levels, either by closed incu-bating pouches (in some cladocerans andisopods), semi-closed pouches (where os-molality is at least partially controlled by thediverted female urine, in some amphipods),or more generally by egg membranes (inspecies whose eggs are directly exposed tothe ambient medium). In some species, tem-porary (e.g. dorsal organs in amphipods) ordefinitive (e.g. gills in crayfish) osmoregula-tory organs, where ionocytes are located,develop in embryos and the activity of Na-KATPase increases concomitantly. The abilityto osmoregulate is thus acquired during theembryonic development, resulting inosmoregulating hatchlings, which is a nec-essary and key adaptation for species spend-ing their entire life-cycle at low (particularlyin fresh water), high or variable salinity.

S4 CHARMANTIER, G. *, WOLCOTT, D.L., University of Montpellier, France, Univer-sity of North Carolina, Raleigh. Ontogeneticstrategies of invertebrates in aquatic envi-ronments: introductory note.

Aquatic organisms are subjected to mul-tiple environmental factors wielding a se-lection pressure upon them. As natural se-lection acts on all developmental stages, thesuccessful establishment of a species in agiven habitat depends on the ability of eachof its developmental stages to accommodate

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these external conditions and their varia-tions. Species may show congruence in be-havioral and physiological strategies that areconstrained by the rigors of the aquatic en-vironment, especially during development.The evolutionary consequences are impor-tant, and have generated increasing inter-est. The symposium, which brings togetherphysiologists and ecologists, aims at a bet-ter understanding of ontogenetic strategiesin aquatic environments, and their evolution-ary significance. The symposium will suc-cessively focus, largely in crustaceans, onthe ontogeny of gas exchange (N.B.Terwilliger), cardiac function (J.I. Spicer), os-moregulation (G. Charmantier), the appear-ance of hormonal coordinations (E.S.Chang), on vision (T.W. Cronin), on induc-tion of quiescence and diapause (S.C. Hand),and on transition to non-marine conditions(K. Anger). Behavioral and ecological as-pects of transport, settlement (R.B. Forward,C.M. Young), and metamorphic competence(M.J. Hadfield) in several invertebrate phylawill also be addressed. D.L. Wolcott will actas panel moderator.

13.2 CHEEK, A.O.*, BROUWER, T.H.,CARROLL, S., MANNING, S.,MCLACHLAN, J.A., BROUWER, M.,Southeastern Louisiana University,Hammond, University Southern Missis-sippi, Ocean Springs, University SouthernMississippi, Ocean Springs, UniversitySouthern Mississippi, Ocean Springs,Tulane University, New Orleans, LA, Uni-versity Southern Mississippi. Experimen-tal evaluation of vitellogenin as a predic-tive biomarker for reproductive disruption.

Vitellogenin (VTG) synthesis in maleoviparous vertebrates is used as an indica-tor of environmental estrogen exposure, yetthe reproductive consequences of exposureare unknown. To examine whether VTG ex-pression predicts reproductive impairment,we exposed medaka fry (Oryzias latipes) for2 or 8 weeks post-hatch to 0, 0.5, 1.0, 2.5,and 7.5 ppb of the environmental estrogeno, p’ DDT. Fish were sampled 2, 4, and 8weeks after hatch to examine gonad histol-ogy and VTG expression. After exposure,fish were transferred to clean water, grown

to sexual maturity, and placed in matingpairs. Eggs were collected for 7 days andscored for fecundity, fertility, and hatchingsuccess. Two week exposure had no effecton VTG expression, while all doses inducedVTG after 8 weeks. The highest doses ofDDT caused a female-skewed sex ratio inadults. Gonadal feminization appeared tobe progressive - some ovotestes appearedafter 2 and 4 weeks exposure to the two high-est doses, but the proportion of ovaries in-creased after 8 weeks. Both two and eightweek exposure significantly reduced fertilityand hatching success at all doses, but lowerdoses had a greater effect after longer ex-posure. Fertility and hatching success weremore sensitive to estrogenic disruption thanwas VTG synthesis. Therefore, VTG expres-sion may be interpreted as a warning of re-productive consequences, but absence ofexpression cannot be interpreted as absenceof developmental and reproductive disrup-tion.

P3.41CHENG, C.-H.C., University of Illinois,Urbana. Antifreeze glycoprotein genes intemperate water notothenioid fish infer anAntarctic origin of speciation.

The perciform suborder of otothenioidfishes is indigenous to the Southern Oceanand largely endemic to the Antarctic region.Currently 8 families encompassing ~130species are recognized. Twelve speciesmakes up 3 basal, non-Antarctic families in-habiting the temperate regions of S. America,Australia, and New Zealand. The majority ofthe species make up the other 5 families,most of which are confined to the Antarcticregion; only about 14 species of these havea sub-Antarctic and south temperate distri-bution. The Antarctic water is isolated fromother southern oceans by the Antarctic Cir-cumpolar Current (ACC), a major oceano-graphic barrier which also prevents dis-persal of fish in either direction. The 3 basalfamilies presumably diverged and becamealong the south temperate continents be-fore Antarctica was fully isolated (22-25mya).The 5 endemic Antarctic families are thoughtto have arisen in situ within the Antarctic wa-ter, the result of an adaptive radiation under-went by the ancestral notothenioid stock

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which evolved antifreeze glycoproteins(AFGP) to avoid freezing as the Antarctic wa-ter chilled to subzero temperatures. Giventhe ACC barrier to dispersal, the origin ofthe extant south temperate notothenioidshas been an enigma. Since AFGP geneevolved once before the notothenioid radia-tion, and its evolution was directly linked tothe freezing of the Antarctic water, the pres-ence of AFGP genes in the extant temper-ate water notothenioids can be used as amarker to infer their geographic origin ofspeciation. Several species were found tohave AFGP genes, two even express theprotein at low levels, which would argue foran Antarctic origin of speciation where andwhen antifreeze protection was needed, anda subsequent escape to the south temper-ate regions.

8.5 CHIU, C.-H. P.*, WAGNER, G. P.*, YaleUniversity. Molecular evolution across the fin-limb transition.

Evolutionary innovations in morphologi-cal characters are realized through the evo-lutionary modification of genes controllingthe development of the characters. We fol-low this line of thought and examine the evo-lution of genes involved in the developmentof fins and limbs to gain insights into themolecular underpinnings of the origin of tet-rapod limbs. Specifically we study the cod-ing and non-coding regions of Hoxa-11 andHoxa-13. The coding region of Hoxa-11 doesnot show a burst of substitutions in most ofits coding region during the fin-limb transi-tion. There is, however, an association be-tween the presence of a cluster of Alanineresidues in the Hoxa-11 protein and the de-rived expression pattern of Hoxa-11 typicalfor eu-tetrapods. In the non coding regionwe find several conserved sequences. Oneprotein binding sequence is found in the in-tron and is conserved between zebra-fish,coelacanth and tetrapods. Another one isfound in the 5í non-coding region and showsa clade specific pattern of sequence con-servation and protein binding. This resultsuggests that it may represent a tetrapodspecific enhancer element. The coding re-gion of Hoxa-13 also shows a tendency toacquire Alanine repeats, but in contrast to

Hoxa-11 this event is not associated withthe fin-limb transition but with the origin ofthe mammals. We conclude that the com-parison of sequences among fish and tetra-pods reveals several candidate differencesthat may be involved in major developmen-tal transformations during the evolution ofvertebrates.

36.3 CHRISTIANS, J.K., WILLIAMS, T.D. *,Simon Fraser University, Burnaby, BC. Ef-fects of porcine follicle-stimulating hormoneon the reproductive performance of femalezebra finches (Taeniopygia guttata).

It has been suggested that follicle-stimu-lating hormone (FSH) may play a role in eggsize/number trade-offs in oviparous verte-brates. We tested this hypothesis in an avianspecies by administering porcine FSH(pFSH) to intact, captive female zebra finches(Taeniopygia guttata) during egg formation.We predicted that 1) low doses of pFSH wouldincrease yolk deposition and so increaseegg mass; 2) higher doses of pFSH wouldincrease the number of ovarian follicles re-cruited into rapid yolk development, and soincrease clutch size; and 3) an increase inclutch size at high doses would lead to areduction in egg size. Although a range ofpFSH doses decreased egg mass by ca.10% in three separate experiments, the re-duction in egg mass occurred in the absenceof an increase in clutch size. Porcine FSHactually reduced the number of eggs laid,although only the difference in median clutchsize (and not mean clutch size) was statisti-cally significant in two experiments. The re-sults of this study did not support the hypoth-esis that FSH mediates a trade-off betweenegg size and clutch size in birds.

P1.58CHRISTMAN, T.M.*, FINKLER, M.S.,Indiana University Kokomo. Overwinteringenergetics of the red-backed salamander,Plethodon cinereus.

Red-backed salamanders are known toactively forage during the winter. The presentstudy examined the importance of success-ful foraging to the overall energy budgetduring overwintering. We measured oxy-gen consumption rate and whole-body trig-lyceride and glycogen contents before andafter a five-month overwintering period in

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salamanders that were either unfed or fed 5fruit flies 3x per week. Oxygen consumptionincreased markedly over the course of over-wintering, with a nearly two-fold increase infed animals. Unfed animals initially hadgreater rates of oxygen consumptio than didfed animals, but this difference disappearedby the end of overwintering. The triglycerideand glycogen contents of fed animals at theend of overwintering did not differ from thoseat the beginning of overwintering, whereasboth values decreased significantly in unfedanimals. Though preliminary, the data sug-gest that winter foraging may be an impor-tant component of the energy budgets of P.cinereus. Moreover, the data highlightchanges in metabolic rate during the courseof overwintering that may need considerationin estimates of overwintering energy bud-gets.

P3.50CHUNFA, W., PATINO, R.*, DAVIS,K.B., Texas Tech University, Texas Tech Uni-versity, University of Memphis. Cellular dis-tribution of estrogen receptor alpha and betatranscripts in the testis of channel catfish.

The cellular distributions of estrogen re-ceptor ALPHA (ER-ALPHA) and ER-BETAin the testis have not been determined andcompared in non-mammalian vertebrates.In this study, we examined the cellular distri-butions of ER-ALPHA and ER-BETA RNA inthe testis of adult and juvenile channel cat-fish by in-situ hybridization. The cRNA probesused contained 5'-terminal end sequencethat is specific for each receptor subtype. Tu-bules in the anterior region of the catfish tes-tis contain the germinal elements, and in theadult fish examined the tubules were sper-matogenic and had free sperm. Hybridiza-tion signal strength (antisense probe) for bothreceptor subtypes was low in primary sper-matocytes and increased in secondary sper-matocytes and spermatids. The most abun-dant signals for ER-ALPHA and ER-BETARNA were observed in sperm. The presenceof ER transcript in spermatogonia could notbe determined since it was difficult to iden-tify these cells in the hybridized tissue sec-tions. Tubules in the posterior region of thecatfish testis contain non-germinal colum-nar epithelium, and weak signals for ER-

ALPHA and ER-BETA RNA were detectedin the vicinity of the apical nuclei. The testesof the juvenile (pre-spermatogenic) catfishexamined also showed signals for ER-AL-PHA and ER-BETA RNA, preferentially inthe stroma. In conclusion, ER-ALPHA andER-BETA genes are both transcribed in thecatfish testis and in the same cell types. Theirtranscripts are found preferentially in thegerm cells of adult males and in the testicu-lar stroma of juvenile males. Of particularinterest is the high level of ER RNA contentin sperm. These observations suggest thatestrogens play important roles in the regu-lation of testicular physiology and spermato-genesis in channel catfish.

P1.25CIURA, S.M., BIBEAU, M.R.,SCHULTE, P.M.*, University of Waterloo,Ontario. Intraspecific variation in heat shockproteins and thermal tolerance.

Populations of Fundulus heteroclitus aredistributed through a thermal cline along theAtlantic Coast of North America, from New-foundland to Florida. At the northern end ofthe species range, fish experience averageannual temperatures ~12 degrees coolerthan their southern counterparts. To deter-mine the maximum critical temperature (CT

max) of fish from the northern and southernpopulations, fish were acclimated to com-mon conditions of 20 degrees celcius in thelaboratory. These fish were exposed to in-creasing water temperature at a rate of 0.3degrees per minute until they were unableto maintain their orientation. CT maxwas sig-nificantly higher in the southern population(p<0.01). To address the molecular basis ofthis difference, we have cloned and se-quenced the 70 kD heat shock protein andheat shock cognate from both populations.There are several amino acid differencesbetween the two genotypes, which could befunctionally important. We have also exam-ined circadian variation in thermal tolerance.In fish held at short-day photoperiod, but atconstant temperature, there is a diurnalrhythm in CTmax, with thermal tolerance atnoon being significantly higher than earlymorning and evening values. In contrast, fishheld at a long-day photoperiod do not ex-hibit this diurnal rhythm. Values of CT max for

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these fish are uniformly high. The diurnalrhythm at short-day photoperiod could rep-resent a strategy for coping with daily varia-tion in temperature during the spring andfall in the natural habitat.

33.2 CLAIBORNE, J.B.*, GUNNING, D.L.,WALL, B.P., MORRISON-SHETLAR, A.I.,Georgia Southern University, Statesboro. GillNa+/H+ antiporters (NHE) in marine fish.

The branchial epithelium in marine fishis the main site of acid-base transfers be-tween the extracellular space and the envi-ronment. Na+/H+ exchange proteins (NHE)are thought to contribute to net acid excre-tion in these animals. We have used mo-lecular and biochemical methods to detectthese antiporters in the branchial epitheliumof two species of fish. 3'/5'-RACE reactionsallowed us to clone and sequence for thefirst time a full length cDNA transcript for anNHE-2-like isoform from the gills of the ma-rine long-horned sculpin (Myoxocephalusoctodecimspinosus). The open readingframe is approximately 2890 bp in lengthand has a ~57% amino acid homology tothe rat NHE-2 isoform with much lower ho-mology at the 3' end. We have previouslyshown NHE-1 like immunoreactivity in thegills of the sculpin and the seawater adaptedmummichog (Fundulus heteroclitus). UsingWestern analysis on gill membrane prepa-rations from fresh and seawater adaptedmummichogs, we have now observed pro-teins approximately 80 kDa and 77 kDa insize that are immunoreactive to antibodiesmade against mammalian NHE-1 (aa 514-818) and NHE-3 (aa 528-648), respectively.Following exposure of this species to 1%hypercapnia for one hour, an increase inexpression was detected for both NHE-likeprotein isoforms in seawater adapted ani-mals, while no difference in expression ofNHE-1-like proteins could be detected infreshwater adapted fish. We hypothesize thatduring acidosis, apical gill NHE activity en-hances net H+ transfers to the water in thesemarine species. Supported by NSF-IBN-9808141 to JBC and AIMS.

S12.4CLARK, T.M., Indiana University SouthBend. Integrative aspects of epithelial trans-port in larval Aedes aegypti.

In contrast to the extensively studied hor-monal regulation of Malpighian tubule func-tion, regulation of midgut transport has beenlargely ignored. 5-hydroxytryptamine (5-HT;serotonin) is perhaps best known amonginsect transport physiologists as one of asuite of hormones regulating Malpighian tu-bule function. In larval Aedes aegypti, Mal-pighian tubule secretion rates are stimulatedby increasing hemolymph 5-HT concentra-tions as ambient salinity increases. First prin-ciples dictate that larvae must coordinatechanges in Malpighian tubule secretion rateswith selective recovery of water and ions inother regions of the excretory system to re-main in homeostasis as ambient salinitychanges. Recent evidence suggests that themidgut is involved in this coordinated regu-lation of hemolymph composition. 5-HT atconcentrations known to exist in hemolymphand to stimulate Malpighian tubule transporthyperpolarizes the transepithelial potentialof both the anterior and the posterior stom-ach regions. 5-HT regulates different mecha-nisms in the two regions. The actions of 5-HT in anterior stomach are confined to thebasal membrane of a subset of cells. Thephysiological significance of stimulation ofmidgut and Malpighian tubule function by asingle hormone is not yet understood. How-ever, stimulation by 5-HT of both midgut andMalpighian tubule transport provides sup-port for a model in which the actions of mul-tiple systems are coordinated by asingle hor-mone to regulate hemolymph composition.Furthermore, stimulation by 5-HT of midgutand Malpighian tubule transport in responseto saline loads in exopterygotes (Rhodnius),and endopterygotes (Aedes), suggests thatits primary function as a regulator ofhemolymph composition through coordi-nated actions on organ systems tradition-ally considered separately may be veryhighly conserved among insects.

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P1.81CLARK, T.M.*, HUTCHINSON, M.J.,MOFFETT, D.F., Indiana Univ, South Bend,Washington State Univ, Pullman, Washing-ton State Univ, Pullman. Apical surface mor-phology of the stomach region of the larvalmosquito midgut.

Mature 4th instar larval Aedes aegyptimeasuring 6.5±0.19 mm in length have astomach region of 3.3±0.18 mm (N=6). Thestomach is clearly differentiated into distinctanterior, transitional and posterior regions(53.0±1.16%, 13.7±1.16%, and 33.3±0% oftotal stomach length respectively). The ante-rior stomach consists of cells that range from5.7 to 44.4 mm in diameter (mean 28.6±1.68mm). These cells are uniform in appearanceand show a normal distribution by diameter.They have polygonal, flat apical surfaceswith very short microvilli (0.4±0.02 mm).There are no intercellular clefts apparent atthe level of SEM, rather the surface of theepithelium is smooth. The most anterior cellsof the transitional region are similar in ap-pearance to cells of the preceding anteriorstomach region but have microvilli 1.2±0.03mm in length. Microvillar length increases to2.3±0.26 mm in the mid-transitional region,and to 4.2±0.25 mm in the posterior transi-tional region. The mean diameter of transi-tional region cells is 21.0±1.26 mm. The tran-sitional region cells show a progression to amore rounded apical profile from anterior toposterior. Posterior stomach cells are char-acterized by globular protrusions of the api-cal surface that are separated by relativelydeep clefts containing numerous microvilli,that were not observed in other stomach re-gions. Posterior stomach cell diameter isuniformly 19.7±1.08 mm throughout the an-terior 2/3 of the posterior stomach (N=22)and increases to 26.2±1.45 mm (N = 8) inthe posterior third of the posterior stomachregion (P<0.0005).

59.2 CLIFFORD, A.B.*, WITMER, L.M., OhioUniversity, Athens, Ohio University Collegeof Osteopathic Medicine. The narial anatomyof hooded seals (Cystophora cristata) withrespect to other Carnivora.

Male hooded seals (Phocidae:Cystophora cristata) have two inflatable de-vices, both of which involve modification of

their narial and facial anatomy. 1) An inflat-able integumentary bladder is formed as theelastic and hairy epithelium covering thenarial region is inflated following closure ofboth nostrils. 2) The “red bladder” is formedas a highly elastic portion of the nasal septalmucosa is extruded out one nostril with thecontralateral nostril shut. Both devices areused as visual displays, the first year roundand the second during the mating season.The unique narial anatomy of adult malehooded seals was studied via CT scanning,dissection, and skeletonization of freshheads. Comparisons involved similar stud-ies of adult female and juvenile hoodedseals, and adults of bearded seals, blackbear, and coyote; skulls of other phocid andotariid species were examined. Among theanatomical specializations associated withthis functional complex are expansion of thenasal vestibule, retraction of the bony naris,increased elasticity in the narial skin andmembranous nasal septum, transformationof the nasal cartilages, elaboration of cer-tain facial muscles that are inconspicuousin outgroups, and changes in numerousbony features. Adult female and juvenilehooded seals are skeletally more like adultmales but the associated soft tissues are lessdeveloped. Oddly, the mechanism of nostrilclosure remains enigmatic. The functionalanatomy of the hood is important in that it isthe nominative attribute of the species; more-over, it has bearing on the general evolutionof probosces in mammals and even on in-ferences of similar inflatable narial structuresin extinct taxa such as hadrosaurian dino-saurs.

S2.2 COATES, M.I., University College Lon-don. Fins to limbs: what the fossils say.

The fin to limb transition is one of the piv-otal morphological transformations in verte-brate history. Fossil outgroups of tetrapodsbear fins with a simple iterative pattern ori-ented proximo-distally; several features ofthese fins are also present in extant lung-fish. Certain examples of fossil fins long con-sidered close to tetrapod limbs, have nowbeen removed to more remote phylogeneticpositions. Their apparent similarities thusappear convergent. The most derived ëfishí

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(i.e. pre-limbed) members of the tetrapodstem-lineage (panderichthyids) show mod-est enlargement of the fin-girdles. This coin-cides with reduction of endoskeletal out-growth, the presence of an expanded plateadjacent to the probable homologue of theintermedium, and changes in the proportionsof proximal fin radials to more closely re-semble the humerus, radius and ulna ofprimitive, digited, limbs. The earliest limbsdate from the uppermost Devonian (360mya). Of these, the forelimb of Acanthostegais arguably the most primitive. Like otherDevonian examples it is polydactylous, but,uniquely, the wrist includes only a single,cylindrical, bone, quite unlike cross-articu-lating wrist and ankle structures of more re-cent limbs. All known primitive hindlimbsinclude a well ossified ankle, but in the ear-liest examples this includes fewer and largerelements than in more recent, derived, limbs.Functionally, these simple ankles are con-sistent with a likely paddle-like function. Themost recent phylogenetic analyses indicatethat pentadactyly evolved once, at a nodewithin the tetrapod stem-lineage precedingthe divergence of amniotes andlissamphibians. By this point in tetrapodphylogeny, it is also noticeable that markersof muscle insertion areas have moved proxi-mally, corresponding to greater developmentof the endoskeletal girdles.

18.2 COATES, M.M.*, THOMPSON, S.H.,Stanford University. Vision in a cubozoan jel-lyfish.

Jellyfish of the class Cubozoa possesscamera-type eyes similar to those of cepha-lopods and vertebrates; consisting of a lens,cornea, and retina. The retina is composedof three layers: a sensory layer, a pigmentedlayer, and a nuclear layer with extendingnerve fibers. The cells of the retina are allciliated primary photoreceptors. These com-plex eyes are located on sensory clubs calledrhopalia. Each animal has four rhopalia, andeach rhopalium has two camera-type eyesas well as four simple ocelli. In spite of allthis visual hardware, little is known of thevisual capabilities of these animals and spe-cifically the function of the remarkable com-plex eyes. We want to determine what infor-

mation these eyes extract from the environ-ment and how the nervous system processesthat information. We are studying these ques-tions using behavioral and electrophysiologi-cal approaches. At Hopkins Marine Station,we have established a colony of Tripedaliacystophora, a small cubozoan from PuertoRico. These cubomedusae exhibit strongattraction to light. Taking advantage of thisbehavior, we measured the spectral sensi-tivity curve of the eye and performed wave-length discrimination experiments. We thenused extracellular recording methods tomeasure the electroretinogram (ERG) of thecomplex eye in response to flashes of differ-ent wavelengths and durations. This allowedus to compare the spectral sensitivity of be-havioral responses to the retinal spectralsensitivity and to learn response time char-acteristics. This will help elucidate the typeand quality of visual information available tothis cubozoan. Funding: NSF and MyersGrant to M.C.; NSF to S.T.

S1.4 COCROFT, R. B., University of Mis-souri, Columbia. Vibrational communicationand the ecology of group-living insects.

I will review the role of vibrational com-munication in group-living, herbivorous in-sects (not including eusocial insects). So-cial behavior in these taxa includes paren-tal care of aggregated offspring, as well asgrouping among cohorts of immatures oradults. I focus on the ways in which the eco-logical context favors cooperation or com-petition within groups, and how these out-comes are mediated by communicationamong group members. I will highlight stud-ies of two membracid treehoppers with dif-ferent life histories, in which siblings com-municate in relation to important features ofthe environment. In both species, signalinginteractions contain a large element of co-operation. I also survey examples of com-munication in other group-living herbivorousinsects, exploring the possibilities of con-vergence in signaling systems that functionin similar ecological contexts.

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62.4 COLLIN, R.*, CHAPARRO, O. R.,University of Chicago and The Field Mu-seum, Universidad Austral, Chile. Loss offeeding larvae in Crepidula (Gastropoda:Calyptraeidae) is not irreversible.

It is thought that species of marine inver-tebrates with planktotrophic developmentcommonly give rise to species with directdevelopment. Direct developers often losethe complex morphological characters nec-essary for planktotrophic development andtherefore cannot give rise to species withplanktotrophic larvae. Here we show that,contrary to expectation, planktotrophic de-velopment in Crepidula fecunda appears tobe derived from a direct developing ances-tor, C. dilatata. Phylogenetic analysis of 640basepairs of cytochrome oxidase subunit ImtDNA show that C. fecunda nests within aparaphyletic C. dilatata and that the threesuccessive sister groups are all species withdirect development. The direct developingembryos of C. dilatata retain a velum with afunctional oposed band ciliary mechanismand a complete gut. These morphologicaland phylogenetic data both support the sce-nario in which the planktotrophic C. fecundaarose from the direct developing C. dilatata.

23.5 COMBES, S.A.*, TRIMBLE, A.C.,DANIEL, T.L., University of Washington, Se-attle. Spatial profiles of wing stiffness in hawk-moths and dragonflies.

Insect flight performance dependsstrongly on the dynamic geometry of wings.The curvature of the trailing edge, in particu-lar, is a crucial determinant of aerodynamicforce generation. In insects, wing curvatureresults from the instantaneous interactionbetween aerodynamic forces and bendingstiffness. If bending stiffness varies spatially,then regional flow control is possible, sug-gesting a passive mechanism of stability. Toexamine this structural heterogeneity andits consequences for flight aerodynamics,we characterize spatial variation of wing flex-ural stiffness in both the spanwise andchordwise direction of insect wings. Wemeasure the surface shape of wings bymultiple laser ranging techniques, and thencalculate flexural stiffness along the wing bycomparing the surface shape of wings be-

fore and after loading the tip with a knownforce. We compare the spatial distribution ofwing stiffness in the hawkmoth, Manducasexta, and an aeshnid dragonfly, Aeshnamulticolor. These insects, both excellent fli-ers, differ greatly in wing shape and vena-tion pattern. Despite such morphological dif-ferences, we find that the profile of flexuralstiffness in the spanwise direction is remark-ably similar in both species, with a peak instiffness located between 1/3 and 1/2 of wingspan, and a sharp drop in stiffness (~2 fold)past this point. In contrast, chordwise stiff-ness differs in the two species; in Manduca,stiffness falls sharply towards the trailingedge, while the dragonfly does not displaythis abrupt drop. Thus, trailing edge curva-ture and chordwise flow may differ signifi-cantly in these species.

9.3 COOKE SCHREIBER, S.M.*, JURY,S., WATSON, W.H., University of New Hamp-shire, Carribean Marine Research Center,University of New Hampshire. Seasonal dif-ferences in behavioral thermoregulation inthe lobster, Homarus americanus.

Lobsters in the Great Bay estuary (NH)undergo a seasonal migration, possiblycued by changes in water temperature. Pre-vious work on their thermal preference indi-cated that lobsters gravitate toward a finalthermal preferendum slightly above normalsummer conditions (Crossin et al., 1998). Weconducted avoidance studies, during whichlobsters were exposed to increasing tem-peratures (rate of change < 0.2ƒC/min) untilthey left their shelters. “Summer-acclimated”lobsters (~15ƒC) exhibited avoidance re-sponses when the temperature reached~22ƒC, well above their preferred range of15-18ƒC. However, winter lobsters (ambi-ent = ~4ƒC) exhibited avoidance behaviorsat ~13.5ƒC, before the temperature reachedtheir preferred levels. This suggests thatavoidance behaviors are initiated by a rela-tive increase in temperature (+7-9ƒC) ratherthan by exposure to an absolute tempera-ture. Heart and ventilation rates also showeda linear increase in rate over most of therange of observed estuarine temperatures(Q10 = 1.8, 5-20ƒC). Thus, an increase of 7-9ƒC would approximately double their me-

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tabolism. Our working hypothesis is that,during these fairly rapid thermal increases,lobster movements are triggered by changesin metabolic rate, rather than sensory inputsindicating a rise in temperature or an abso-lute temperature. This study was supportedby NOAA (SeaGrant) and the USDA (Hatch).

P3.83COOMBS, S.*, ANDERSON, E.J.,BRAUN, C.B., GROSENBAUGH, M.A.,Loyola University Chicago, Woods HoleOcean. Inst. How fish body parts alter localhydrodynamic stimuli to the lateral line.

Mottled sculpin (Cottus bairdi), like manyfish, use their lateral line system to form hy-drodynamic images of the environment. Al-though these small (~10 cm long), benthicfish inhabit streams and lakes with signifi-cant ambient water motion, informationabout lateral linefunction comes largely fromstill-water conditions. We used digital par-ticle image velocimetry to determine howuniform flow fields (2 - 8 cm/s) near thesculpin were altered along a horizontal planeat the level of the trunk lateral line canal. Inthe absence of the fish and at distances > 2cm away from the fish, the mean directionand magnitude of the flow field was spatiallyhomogenous at all flow speeds. Small scale(< 5 cm), ambient turbulence was negligibleat 2 cm/s, but increasingly more pronouncedat higher flow speeds. Flow around the fish’shead, pointed upstream, was typical for thataround a rigid body and could be predictedby a potential flow model. Flow around thelarge, extended pectoral fin, pointed down-stream, showed separation at the edge ofthe fin and a trailing wake, similar to thatobserved for a flat plate perpendicular to theflow. A separation bubble or recirculatingregion (1- 2 cm wide) formed behind thepectoral fin and extended along the entiretrunk of the fish. The magnitude of the mean,local flow in this region was significantly lessthan that further away and its direction veryclose to the fish was likewise very different,predominantly upstream. The shear layerdividing the separation bubble from the ex-ternal flow was fairly stable at 2 cm/s (Re ~102), but very unstable and wave-like at 8cm/s (Re~103). These results show that fishbody parts like the pectoral fin can signifi-

cantly alter the local hydrodynamic stimulusfield to the lateral line relative to ambientwater motions only a few centimeters away.

P3.89COOPER, R.L. *, TABOR, J., CHASE,R.J., University of Kentucky. Altered respon-siveness to 5-HT at the crayfish neuromus-cular junction: receptor up- & down-regula-tion.

Serotonin (5-HT)levels in the hemolymphof crustaceans has been implied to alter theassertiveness and aggression during socialinteractions (Huber et al., 1997; Sneddon etal., 2000). Pharmacological examinationshows that m-CPP has agonistic functionsin crayfish altering sensory drive into the ani-mals ventral nerve cord (Yeh et al., 1996),thus suggesting the presence of one or both5-HT1 and 5-HT2 receptor types. Based onevidence in other systems, one would sus-pect that chronically sustained 5-HT levelswould results in a compensatory negativefeed-back regulation and/or that target tis-sues would diminish their sensitivity to highlevels of circulating free 5-HT. Altered cellu-lar activity as well the action of agonists orantagonists being bound to a receptor caninduce regulation in the levels of functionalreceptors (Welner et al., 1989; Kokay andMercer, 1997; Fone et al., 1998). For exampleit has been shown that 5-HT1A receptorswill demonstrate desensitization when ei-ther an agonist or antagonist is present(Hensler and Truett, 1998). The purpose ofour study is to address the issue of up- anddown-regulation in the sensitivity of the re-sponsiveness to exogenously applied 5-HTat the neuromuscular junctions (NMJs) ofcrayfish in which the animals have had ei-ther reduced endogenous 5-HT levels byenzymatic inhibition in the synthesis of 5-HTor have had a chronic presence of an ago-nist in their hemolymph. Injections of the 5-HT1 and 5-HT2 vertebrate receptor agonist,m-CPP, for 1 week resulted in a decreasedresponsiveness to 5-HT. The reduction ofsystemic 5-HT by injections of p-CPA, whichblocks the synthesis of 5-HT, resulted in asupersensitivity of both tonic and phasicNMJs.Funding: NSF grants IBN-9808631(RLC) & NSF-ILI-DUE 9850907 (RLC).

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P1.59COOPER, S.J.*, SAME, D.R., Univer-sity of Wisconsin, Stevens Point. Ventilatoryaccommodation under cold stress in sea-sonally acclimatized black-capped chicka-dees.

Black-capped chickadees undergo sea-sonal acclimatization that is characterizedby an increase in both basal and summitmetabolism in winter birds compared to sum-mer birds. Little is known about how theavian ventilatory system accommodates thelarge changes in rates of oxgyen consump-tion (VO2) between basal (BMR) and sum-mit metabolism (VO2sum). We measured ven-tilation and VO2 under thermoneutral condi-tions and cold stress in seasonally acclima-tized black-capped chickadees. Cold stresstests were conducted using a gas mixture of79% helium and 21% oxygen (helox). Meta-bolic expansibility (VO2sum/BMR) was 5.5 insummer and 6.7 in winter. For summer birds,the increase in VO2 under cold stress wasaccommodated mainly by an increase in tidalvolume (VT). For winter birds, the increase inVO2 under cold stress was accommodatedby decreased respiratory frequency, an in-crease in VT and a significant increase inventilatory oxygen extraction (EO2). The win-ter EO2 of 68.3% was significantly higherthan summer birds (42.5%) and is the high-est value so far documented in birds. Therewere no other significant differences in ven-tilation between summer and winter birdsunder thermoneutral or cold stress condi-tions. Our data suggests that changes inEO2 are involved with seasonal acclimati-zation to cold in black-capped chickadees.

65.1 CORLEY, L.S.*, STRAND, M.R., Uni-versity of Wisconsin, Madison. Regulationof caste fate in the polyembryonic wasp,Copidosoma floridanum.

Striking morphological differentiationamong individuals structures the complexsocieties found in insects such as termites,bees, and ants. Castes have also evolved inother insects such as aphids, thrips and poly-embryonic wasps. Copidosoma floridanumis a polyembryonic parasitoid wasp that pro-duces two castes during development froma single egg. Polyembryonic developmentresults in a single brood containing approxi-

mately 1000 reproductive larvae that de-velop into adult wasps and 50 precociouslarvae that function as soldiers. We exam-ined how the single egg proliferates and re-sponds to environmental factors to producetwo castes in C. floridanum. We conductedtransplantation experiments of wasp em-bryos from all developmental stages intounparasitized hosts from all developmentalstages. By transplanting wasp embryos of aparticular stage into different host environ-ments, we partitioned the effects of the in-trinsic properties of the embryos from theextrinsic factors (i.e. — the host environment)influencing caste fate. Our results indicatethat both intrinsic and host environmentalfactors affect caste formation in this species.

10.4 COSTA, D.P.*, GALES, N.J, GOEBEL,M.A., Univ of California, Santa Cruz, Con-servation and Land Management, WesternAustrali, AMLR National Marine FisheriesService. The role of physiology in the be-havior of diving mammals.

Diving animals offer a unique opportu-nity to study the role physiology in limitingbehavior. An important component of thephysiological capability of any diving ani-mal is it's aerobic dive limit (ADL). The ADLhas only been measured in a few species.The goal of this study was to estimate theaerobic dive limit from measurements ofbody oxygen stores and at sea metabolism.This calculated ADL was compared to mea-surements of diving behavior of individualanimals of three species of otariids, the Ant-arctic fur seal, Arctocephalus gazella, theAustralian sea lion, Neophoca cinerea andthe New Zealand sea lion, Phocarctoshookeri. Antarctic fur seals dove well withinthe cADL. In contrast, many individuals ofboth sea lion species exceeded the cADL.Australian and New Zealand sea lions dove1.4 times longer than the cADL. The ten-dency to exceed the cADL was correlatedwith the dive pattern of individual animals.In both Antarctic Fur Seals and Australiansea lions, deeper diving females made longerdives that approached or exceeded the cADL(P < 0.01, r2 = 0.54). Australian and NewZealand sea lions with longer bottom timesalso exceeded the cADL to a greater de-

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gree. The two sea lions forage on the benthoswhile the fur seals feed shallow in the watercolumn. It appears that benthic foraging re-quires these animals to reach or exceed theiraerobic dive limit.

14.1 COSTANTIO,D.*, KOZAK, K.,LECAUDE, S., ALRUBAIAN, J., DORES,R.M., University of Denver, Colorado. Clon-ing of a proopiomelanocortin cDNA from thepituitary of the urodele amphibian, Aphiumameans.

The proopiomelanocortin (POMC) genehas been cloned from several anuran am-phibians, however, the organization of thisprohormone-coding gene had not been ana-lyzed in a urodele amphibian. A degenerateprimer was used to clone and sequence aPOMC cDNA from the pituitary of the urodele,Amphiuma means. The cloning strategy in-volved the use of a 3’RACE procedure anda 5’RACE procedure. The open readingframe of the A. means POMC cDNA codedfor a 267 amino acid precursor that con-tained the sequences of ALPHA, BETA, andGAMMA MSH, as well as ACTH, and BETA-endorphin. The A. means POMC sequencewas aligned to several anuran POMC se-quences including Xenopus laevis, Speamultiplicatus, Rana ridibunda, and Bufomarinus, and to two lungfish POMC se-quences (African and Australian). As ex-pected, cladistic analyses placed the A.means POMC sequence as the sister groupto the clade of anuran amphibian POMC se-quences. This project was supported by NSFgrant IBN-9810516.

P1.76COSTANZO, J.P., JONES, E.J.*, LEE,R.E., Miami University, Oxford, OH, Univer-sity Indianapolis, Indianapolis, IN, MiamiUniversity, Oxford, OH. Physiological re-sponses to supercooling and anoxia in thehatchling painted turtle.

We investigated physiological responsesto supercooling in hatchling painted turtles(Chrysemys picta), which remain in theirnatal nests over winter. These turtles arefreeze tolerant, but also rely on supercool-ing to survive exposure to the lower tem-peratures occurring in nests during winter.We measured whole-body concentrations

of lactate, glucose, glycerol, and ATP in turtleschilled for 5 days at 0, -4, or -6o C, or chilledfor 19 days at -6o C. In a companion experi-ment we measured metabolite concentra-tions in turtles exposed for 1, 4, or 8 days toan anoxic environment. Chilling and anoxiaexposure both resulted in an increase in con-centrations of lactate and glucose, a de-crease in the glycerol concentration, and nochange in the ATP pool, suggesting that oxy-gen delivery and/or utilization is impaired insupercooled turtles. Anoxia tolerance maybe an important preadaptation for survivingexposure to subzero temperatures inhatchling C. picta.

P1.9 COSTANZO, J.P.*, LITZGUS, J.D.,IVERSON, J.B., LEE, R.E., Miami University,Oxford, OH, University South Carolina, Co-lumbia, SC, Earlham College, Richmond, IN,Miami University, Oxford, OH. Cold hardinessand desiccation resistance in hatchlingturtles.

North American turtles hatch in late sum-mer and spend their first winter either onland or under water. Adaptations for terres-trial overwintering of hatchlings in northernregions, where winter thermal and hydricregimes are harsh, have not been system-atically investigated in many species. Wemeasured intrinsic supercooling capacity, re-sistance to inoculative freezing, and desic-cation resistance in terrestrial and aquatichibernators indigenous to northern(Terrapene ornata, Chrysemys picta bellii,Kinosternon flavescens, Chelydraserpentina) and southern (C. p. dorsalis,Trachemys scripta, Sternotherus odoratus,S. carinatus) locales. Supercooling capacityand inoculation resistance tended to behigher in the terrestrial hibernators, espe-cially C. p. bellii, and terrestrial hibernatorsbetter resisted evaporative water loss. Mostspecies tolerated the loss of a modestamount of body water, although some S.carinatus died during desiccation experi-ments. With the possible exception of T.ornata, turtles did not regain lost body waterfrom wet soil and immersion in free waterwas required for rehydration; therefore, des-iccation resistance is an important adapta-tion to terrestrial hibernation. Resistances

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to inoculative freezing and desiccation weredirectly correlated, perhaps because theyare governed by the same morphologicalattributes.

55.4 COTTER, P.A.*, EVERSON, J.J.,RODNICK, K.J., Idaho State University, Di-agnostic Imaging of Idaho, Idaho State Uni-versity. What comes in must go out:ventricularblood flow patterns in the rainbow trout.

Hemodynamic parameters in fish are of-ten measured using invasive techniques,limiting the use of repeated measure experi-mental designs. We used high-resolution (10MHz) echocardiography, and doppler analy-sis of sagittal images to determine ventricu-lar filling (diastolic) and emptying (systolic)patterns in 3 body-size categories (400-500g, 600-800g, >1kg, n = 2/category) inhatchery-reared, anesthetized, RainbowTrout (Oncorhynchus mykiss) at 14oC. Dop-pler analysis allows determination of bothvelocity (cm/s) and duration of blood flow (s)through atrioventricular and ventriculobulbarvalves. Subtracting end-systolic from end-diastolic volume yielded stroke volume. Wecalculated flow (ml/s) through valves usingstroke volume and diastolic/systolic time.Duration of ventricular systole (mean = 0.41s,SD = 0.07) was independent of body massand approximately 2x that of diastole in allindividuals. Flow (range = 0.9 - 4.2 ml/s) andblood velocity (range = 67.7 - 120 cm/s) ofventricular systole were approximately 50%that observed in diastole. In summary, de-spite size-dependent changes in stroke vol-ume (range = 0.27 - 1.47 ml), the duration ofsystole and diastole, and heart rate remainrelatively constant, suggesting compensa-tory mechanisms are involved in increasingcardiac output with increasing ventricle size.Electrocardiographic (ECG) data collectedconcurrently with echocardiographic/doppler imaging will help decipher the rela-tive contribution of both atrial contraction andventricular relaxation in cardiac blood flowpatterns in the growing trout heart.

S6.2 COUGHLIN, D. J., Widener University,Chester, PA. A molecular mechanism forvariations in muscle function in rainbow trout.

Rainbow trout provide an excellent modelfor the molecular analysis of muscle func-

tion. For several years I have studied a de-velopmental shift in muscle kinetics andswimming performance in trout. At the parr-smolt transformation, red or slow-twitchmuscle of trout undergoes a shift in contrac-tions kinetics. The red muscle of youngertrout parr has faster rates of activation andrelaxation in isometric contractions and hasa faster maximum shortening velocity (Vmax)than that of older trout smolts. Further, parrswim steadily at higher tailbeat frequenciesthan smolts. Molecular biological techniquescan be used to examine the molecular ba-sis for this developmental shift in musclefunction. Because of the observed varia-tions in Vmax, an ontogenetic shift in themuscle protein myosin heavy chain (MHC)may be responsible for changes in musclekinetics. We examined the MHC protein withSDS-PAGE and through cloning and se-quencing MHC mRNAs. SDS-PAGE re-vealed a significant shift in the pattern ofMHC isoforms. Parr red muscle samplestypically have 2-3 forms of MHC, while smoltsamples have 1-2 forms. Densitometry re-veals a statistical difference in the intensityof MHC bands between the two stages, sug-gesting a developmental reduction in MHCisoforms in trout red muscle. Three MHCmRNAs were subsequently cloned and se-quenced, one each from red, white and ven-tricular muscle. Through the use of isoform-specific primer pairs, RT-PCR was used todetermine the expression patterns of thesethree mRNAs in trout red muscle. Parr redmuscle consistently expresses both whiteand red isoforms, and often the ventricularisoform, of MHC. As compared to parr, agreater proportion of the smolt red musclesamples expressed only the red muscleisoform. A shift in MHC expression providesa mechanism for the ontogenetic change inmuscle function in rainbow trout.

26.2 COURTLAND, H.W-.*, WRIGHT, G. M.,DEMONT, M. E., Atlantic Veterinary College,Atlantic Veterinary College, St. Francis XavierUniversity. Physical properties ofnoncollagenous lamprey cartilages.

Morphological and biochemical studieshave demonstrated that lamprey cartilagesare different from other vertebrate cartilages

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in that their major structural components lackcollagen and elastin. Notable biochemicaland morphological variations even suggestthat a family of noncollagenous matrix pro-teins comprises the lamprey’s cartilaginousskeleton. Yet, in spite of this knowledge, themechanical properties of these cartilages re-main a mystery. In order to further our un-derstanding of cartilage structure-functionrelations, we conducted a series of stress-relaxation experiments on lamprey annularand pericardial cartilages. Strains of up to15% were applied in compression (annu-lar) and tension (pericardial). The appliedstrains and measured equilibrium stresseswere used to determine the modulus of elas-ticity for these cartilages. Our results dem-onstrate significant differences between thestiffness of lamprey cartilages and other ver-tebrate cartilages (i.e., hyaline articular car-tilage). In addition, there are noticeable dif-ferences in stiffness between the two lam-prey cartilages.

19.2 COWART, J.D., University of Florida,Gainesville. Palatability of Pterastertesselatus (Echinodermata: Asteroidea)eggs.

Risk of offspring mortality is a critical com-ponent of models concerning the ecologyand evolution of life history traits in marineinvertebrates. In these models, predation isgenerally assumed to be the most importantcause of pre-settlement offspring mortality.Although few studies have directly investi-gated offspring susceptibility to predators,most models evaluating development as-sume that offspring of most species are pal-atable. Pelagic nonfeeding offspring arecommonly large, conspicuous, energy rich,produced in small numbers, and lack ap-parent morphological defenses. Interactionsbetween nonfeeding offspring and consum-ers are not well studied. However, recentstudies have shown that pelagic nonfeedingoffspring may benefit from the production ofchemical defenses. This study investigatedoffspring palatability of the starfish Pterastertesselatus. Members of the pterasterid fam-ily are unique because the adults secretemucus over their aboral surface when at-tacked by predators. In addition, most spe-

cies of pterasterids brood direct developingoffspring within a specialized brood cham-ber called the nidamental chamber. P.tesselatus is unique because it has re-evolved pelagic development. The eggs ofP. tesselatus are large, energy rich, positivelybuoyant, bright orange, and exposed to pe-lagic predators. I hypothesize that the re-evo-lution of pelagic development resulted in theevolution of chemical defenses in the off-spring of P. tesselatus. Preliminary resultssupport this hypothesis by showing that theeggs of P. tesselatus are unpalatable to twospecies of northern pacific fish, Oligocottusmaculosus and Gasterosteus aculeatus.

27.6 COX, D.E.*, BERTRAM, J.E.A., FloridaState University. Hypothesis testing as a labexercise: a simple walking study.

This paper describes a laboratory exer-cise designed to provide students with ex-perience testing a hypothesis by systemati-cally isolating and controlling determinantvariables. The study involves the analysis ofwalking and is performed by the students ona subject from within their lab group. Thestudy requires use of a motorized treadmill,tape measure, stop watch, personal cassetteplayer and calculator. The exercise is de-signed to include factors that the studentsare familiar with, so they can focus on theisolation of parameters without being con-fused about the process they are investigat-ing. However, the exercise will not turn outas they anticipate, meaning they will beforced to re-evaluate the assumptions thatformed the basis of their original hypothesis.This exercise is designed for a college levelcourse in exercise science, physiology orbiology, but could easily be managed by ahigh school honors class with appropriateguidance.

P2.5 CRAWFORD, B.J.*, PANG, T.,CAMPBELL, S.S., U.B.C. Vancouver, B.C.Development of the hyaline layer of the as-teroid Pisaster ochraceus.

Embryos and larvae of the starfishPisaster ochraceus are surrounded by acomplex ECM layer called the hyaline layer(HL). A similar but less well organized ECMlayer lines some regions of the larval gut. Inmaterial preserved with conventional fixa-

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tives to which anionic dyes have been added,the HL consists of three regions, a outercoarse meshwork (CM), a supporting layer(SL) and an intervillous layer (IV). Examina-tion of material preserved by freeze substi-tution shows greater details, i.e. the SL isdivided into three sub layers H1, H2, and H3and has a boundary layer (B), consisting ofshort fibers which are and associated withits outer surface and project into the CM atright angles to the SL. Development of theHL begins at fertilization when exocytosis ofthe cortical granules releases ECM into theperivitelline space and elevates the fertili-zation membrane. Shortly after this plaquesof dense material with attached fibers arepresent on the outer surface of the egg plas-malemma. Following this these plaques andfibers are associated with the tips of shortmicrovilli suggesting that they may inducethe microvillus formation. Next, the tips ofsome of the microvilli are joined by shortregions of the H1 sub layer. Some of theseH1 regions have short segments of bound-ary layer material associated with their outersurfaces while others are naked. Just priorto hatching, the H1 and B layers completelysurround the embryo separating the devel-oping CM and IV layers. Short segments ofthe H2 and H3 sub layers are also begin-ning to appear and extend to surround theembryo. Post hatching, the microvilli and allHL layers increase in thickness and density,particularly the H2, boundary and CM lay-ers. The results suggest a sequential orga-nization of HL components from ECM whichis secreted into the perivitelline space. Sup-ported by NSERC.

30.5 CROLL, G.A. *, MCCLINTOCK, J.B.,University of Alabama at Birmingham. Sexualdimorphism, cheliped assymetry and selec-tion pressure in Uca spp.

Left-right claw asymmetry occurs in avariety of decapod species. The asymme-tries can be present in early development orarise during sexual differentiation. In Ucaspp., males have a dimorphic enlargementof one of the two chelipeds. The larger che-liped has been associated with male repro-ductive success as a result of female selec-tion or advantage in male-male combat. Be-

cause the enlarged cheliped occurs on ei-ther the right or left side, selection pressurecould produce populations with right or leftcheliped dominance. To ascertain whethersuch selection pressure is acting on Ucalongisignalis, U. minax, and U. pugnax,populations of fiddler crabs from four NorthAmerican marshes were sampled; two onthe coast of the Atlantic Ocean, one on theChesapeake Bay and one on the coast ofthe Gulf of Mexico. There were no signifi-cant differences in the proportion of right orleft enlarged chelipeds within males of allsampled species or within marshes (p>0.05).Similarly, when male crabs were groupedarbitrarily into two major cheliped sizeclasses (equal to or greater than 20 mm andless than 20 mm) the proportion of right orleft enlarged cheliped individuals was simi-lar among each of the size groups (p>0.05).Mean major propodus size for males wassimilar for individuals with either right or leftcheliped dominance within each of the threespecies and four marshes (p>0.05). It ap-pears that among these three species ofUca, there is no selection for males with che-liped enlargement on either the right or leftside .

40.1 CROLL, S.L.*, WATTS, S.A., Univer-sity of Alabama at Birmingham. The effect oftemperature on feeding characteristics in twosympatric crayfish species.

Crayfish are an integral component ofmany freshwater habitats. They often impactthe environment through vegetative grazing,burrowing activities, and predation. The redswamp crayfish, Procambarus clarkii (PC),and the white river crayfish, P. zonangulus(PZ), are commonly found in the southeast-ern United States and are important in com-mercial culture activities. Because of theirecological and commercial importancethroughout these temperate regions, the ef-fects of temperature on feeding characteris-tics and, consequently, production are of in-terest. Consumption of a formulated diet, ap-parent dry matter digestibility (ADMD), andcarbohydrate and protein absorption wereexamined after exposure for 3 weeks at 8,14, 20, 26, or 32 C. Sex-specific differenceswere generally not found in either species.

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At 32 C, PC consumed significantly morefeed (30 % body weight per d) than PZ (4 %body weight per d); consumption did not varybetween the species at all other tempera-tures. Consumption averaged 6 and 7 %body weight per d at 26 C in PC and PZ,respectively, a temperature near their re-ported thermal optimum. Consumption wasminimal at 8 C. ADMD ranged from 55-75%regardless of sex, species, temperature, orrate of consumption. Carbohydrate absorp-tion efficiency increased in both species fromapproximately 20 % to 70 % as temperatureincreased from 8 to 32 C. In contrast, proteinabsorption efficiency decreased from 45 %to 5 % as temperature increased from 8 to32 C. PC and PZ maintain a relatively con-stant consumption rate at a wide range oftemperatures, but species-specific differ-ences at high temperatures suggest that PCwill have a potential growth advantage.These data suggest further that theprotein:energy requirements for these spe-cies change with temperature.

P1.90CROSSLEY, D. A.*, BAGATTO, B. P.HICKS, J. W., ALTIMIRAS, J., University ofCalifornia, Irvine, University of NorthTexas,University of California, Irvine, Goteberg Uni-versity, Sweden. Changes in cardiovascu-lar control mechanisms during the embry-onic development of the American alligator,Alligator mississippiensis.

Several ectothermic vertebrates possessa unique cardiac morphology that providesthe potential for differential perfusion of sys-temic and pulmonary vasculatures. Thecrocodilians represent one such group withthe capacity to bypass the lungs, returningdeoxygenated blood to the systemic tissues(R-L shunt). Numerous studies have inves-tigated cardiovascular function and controlin adult crocodilians; however, maturationduring embryonic development remains un-known. This study determined changes incardiovascular function and control duringthe embryonic development (from 30 to 72days) of the American alligator. During de-velopment resting cardiovascular functionchanged markedly, with mean arterial pres-sure rising from approximately 1kPa half waythrough incubation to 3 kPa at hatch. Heart

rate remained relatively constant over de-velopment rising slightly from 80 to 90 beatsper minute. Control mechanisms were com-prised primarily of adrenergic systems withno tonic cholinergic input evident during al-ligator incubation. Baroreflex responsescould be elicited initially at 70% of incuba-tion with a progressive rise in sensitivity.Collectively the data suggest that embryoniccontrol of cardiovascular function differs fromthat known to be present in adult animals.

34.4 CROSSLEY, D. A.*, HICKS, J. W.,BENNETT, A.F., University of California,Irvine. Postprandial changes in cardio-res-piratory responses of the Savannah moni-tor (Varanus exanthematicus).

Cardio-respiratory control has been wellcharacterized in numerous endothermicvertebrates, however our understanding ofthese systems in ectothermic vertebratesremains poorly understood. The purpose ofthis study was to thoroughly assess the car-diovascular and pulmonary responses tochanges in ambient gas composition in theSavannah monitor, Varanus exanthematicus,in a fasted and fed state. Fasted animals ex-posed to graded hypoxia exhibited a venti-latory response characterized by an in-crease in Ve, Vt, fB. These changes were ac-companied by a fall in arterial PO2 andPCO2 while arterial pH rose. In addition,hypoxia resulted in a progressive tachycar-dia but blood pressure remained constant.Graded hypercapnia produced an increasein both arterial PO2 and PCO2 while pH fellduring each exposure. These changes werecoupled with an elevation in all ventilatoryparameters; however, cardiovascular param-eters remained constant. 24 h after ingest-ing a standardized meal, baseline values ofall measured parameters rose with the ex-ception of arterial pressure and pH, whichremained unchanged. Postprandial expo-sures to both the hypoxic and hypercapnicrÈgime produced responses in all measuredparameters that were similar to that of thefasted animal. Thus it appears that the con-trol mechanisms are unaffected by feedingin the Savannah monitor.

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S5.10CROWE, J.H.*, CROWE, L.M., Univer-sity of California, Davis. Anhydrobiosis: aunique biological state.

Anhydrobiosis (“life without water”) is awide-spread phenomenon in all majorgroups of lower organisms. Anhydrobioticorganisms often contain as little as 2% wa-ter content. They persist in the dry state forlengthy periods, but when they are returnedto water they rapidly rehydrate and resumeactive metabolism. The mechanisms under-lying their ability to survive in this uniquestate are becoming well understood; virtu-ally all such organisms produce disaccha-rides at high concentrations, most notably adisaccharide of glucose, trehalose. Treha-lose has the ability to stabilize dry mem-branes and proteins, and, it is emerging, in-tact cells in the absence of water. This stabi-lization involves direct interaction betweenthe sugar and hydrophilic residues inbiomolecules, an interaction that confersupon the molecule a physical state that re-sembles the fully hydrated state. This inter-action, which has come to be called the “wa-ter replacement mechanism” appears to berequired for the stabilization. Recently, thesefindings have been applied to mammaliancells, and it is becoming possible to reducethese cells to a dry state, with excellent re-covery, findings that are likely to have appli-cations in clinical medicine. In the dry state,anhydrobiotic organisms show an arrest ofmetabolism, during which they appear notto age. When the cells are rehydrated, theyresume active metabolism, but the life spanis not shortened by the length of time spentin anhydrobiosis. The same appears to betrue of mammalian cells dried with treha-lose. We suggest that such an effective ex-tension of the life span should have profoundecological and philosophical implications.

P3.47CROWLEY, M.C.*, HATLE, J.D.,ANDREWS, A.L., JULIANO, S.A., IllinoisState University Inter-population differencesin reproductive tactics in lubber grasshop-pers.

For many organisms, a trade-off existsbetween reproductive timing (e.g. age atoviposition) and mass of reproductive out-put (e.g. number of eggs). Within a species,

populations could be predicted to exhibit tim-ing vs. output mass trade-offs that areadapted to their local environment. To testthis hypothesis, we examined three popula-tions of the clutch-laying grasshopperRomalea microptera. We predicted thatgrasshoppers from locations with relativelylong growing seasons would have greatertemporal reproductive plasticity and lessplasticity in egg number. In contrast, grass-hoppers from locations with relatively shortgrowing seasons would have greater plas-ticity in egg number and less temporal plas-ticity. We used Florida (FL), Louisiana (LA),and Georgia (GA) hoppers as our long, in-termediate, and short season populations,respectively. We reared three subsets ofeach population of grasshoppers with high,medium and low amounts of food available.For egg number, within each population,high-fed hoppers laid more eggs than low-fed hoppers. There were no significant dif-ferences in egg number among populationswithin a treatment. For time to oviposition,within each population, high-fed hopperslaid sooner than low-fed hoppers. In con-trast to egg number, there were significantdifferences among populations within atreatment for age at oviposition. Both FL andLA medium-fed hoppers laid significantlylater than GA medium-fed hoppers. Therewere no other significant differences amongpopulations within a treatment. These datapartly support our prediction that, in thetrade-off between reproductive timing andmass output, long season hoppers will ad-just reproductive timing and shorter seasonhoppers will adjust reproductive mass out-put.

S11.13 CRUSE, H.*, SCHUMM, M., Uni-versity of Bielefeld, Germany. The influenceof changing substrate conditions on swingmovement trajectories.

Trajectories of swing movements of stickinsects walking on different forms of sub-strates were studied. When walking on aninclined surface, the body is rotated aroundits long axis such that the vertical axis of thebody is held more vertical than the directionperpendicular to the walking plane. A simu-lation shows that sense organs measuring

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leg joints are sufficient to explain this be-havior. As a result of body rotation, swingmovement trajectories have to be changed.In the downhill legs, the coxa-trochanter jointis more elevated than in the uphill legs. Inthe uphill legs, the femur-tibia joint is ex-tended more which compensates for thesmaller lift in the coxa-trochanter joint, lead-ing to a higher extreme position in the uphilllegs. By experimentally changing the start-ing position of a swing movement in verticaldirection and in the direction parallel to bodylong axis, the trajectories cannot be predictedby an earlier hypothesis. A modified networkallows for a description of the behavioral re-sults. Swing movements depend on thewidth of the substrate. Walking on a widetreadwheel leads to different swing trajecto-ries walking on a more narrow one. The con-tribution of the various leg joints is differentdepending on the substrate, suggesting aneconomical solution. If one joint is near itsupper limit, the parallel neighboring jointmay be activated to meet the goal of legmovement (motor equivalence). The form ofthe swing trajectory depends on the place-ment of the tarsus in the preceding stance. Ifthe tarsus is placed flat on the ground, swingheight is larger than when the tarsus graspsaround an edge. Transition between differ-ent swing trajectories is not gradual. Theform of the trajectory is determined by thecurrent sensory input on a step by step ba-sis.

P1.10CUNNINGHAM, S.L.*, MARIS, R.C.,Mansfield University of Pennsylvania. Theemployment of mini-biocells for thebioremediation of petroleum-contaminatedsoil over a two-week period.

The potential of petroleum spills pos-sesses a significant threat to the natural en-vironment. Such eminences have promptedthe necessity for alternative methods of con-taminated soil treatment. Studies atMansfield University, over the last sevenyears, have centered around the breakdownof toxins by naturally-occurring microbes, orbioremediation. Investigations have utilizedbacterial growth studies with drying and or-ganic ashing in soil excavated from petro-leum spills, and in artificially-maintained in-

ternal biocells. The present study has em-ployed the use of mini-biocells. Six mini-biocells (31 x 17 x 9 cm) were each filledwith 1275 g of soil. These biocells were des-ignated into two groups, open or closed, withcontrol, gasoline, and diesel components.The petroleum-containing units were con-taminated with 350 ml of the correspondingfuel. Daily samples were taken over a twoweek period to examine immediate effectsof contamination on the soil ecosystem.Losses due to evaporation were monitoredusing the open and closed configurations.Obvious changes occurred in the gasolinebiocells, unlike the diesel biocells whichchanged little due to the enhanced complex-ity. Bioremediation has shown to be a viablepotential in the clean-up of petroleum-con-taminated soil.

P3.8 CUNYUS, V.L., GOMEZ, A. L.,JOHNSON, G. W., JOHNSON, J.D., IRWIN,L.N.*, University of Texas at El Paso. Taxo-nomic utility of random genetic variation inlizards.

We have used the randomly amplifiedpolymorphic DNA (RAPD) technique to as-sess the utility of random genomic varia-tion as a taxonomic trait at the Family leveland below. We hypothesized that genomicsimilarity as measured by RAPDs wouldbe greater within families than across fami-lies, and that the variation observed wouldpredict phylogenetic relationships inagreement with traditional assumptions.DNA was extracted from members of thefamilies Crotaphytidae (Crotaphytuscollaris), Phrynosomatidae (Phrynosomamodestum, Sceloporus poinsetti,Urosaurus ornatus, and Utastansburiana), Teiidae (Cnemidophorustigris, C. tesselatus, and C. exsanguis),and Eublepharidae (Coleonyx brevis), am-plified by PCR, and analyzed by agarosegel electrophoresis. Neiís index of similar-ity was 33+15% for 7 pairwise compari-sons within families, and 1+11% for 19pairwise comparisons across families, ahighly significant (U = 18.5, p = 0.003) dif-ference. Using a similarity matrix basedon the RAPD data, a phenogram was con-structed that conforms to traditional as-

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sumptions about phylogenetic relation-ships among and within these families,except that Crotaphytus collaris clusteredamong the Phrynosomatidae. These re-sults support the validity of random ge-nomic variation as a useful taxonomic traitat the Family level and below, and sug-gest that the RAPD technique may dis-close some relationships different fromthose based on other characteristics. Sup-ported by grants from the RCMI (G12-RR0814) and Bridges to the Future pro-grams of NIH. We thank Dr. ElizabethWalsh for significant help and advice.

P2.34CUPP, P.V., Eastern Kentucky Univer-sity. Spatial distribution and site fidelity ingreen salamanders, Aneides aeneus.

Individual green salamanders, Aneidesaeneus (N=94) were captured and identi-fied by the unique pattern of black spots ontheir heads. Individuals were then returnedto the rock crevices from which they hadbeen removed. Additional visits were madeto the same areas in southeastern Kentuckyover a four-year period with 50 animals(53%) being recaptured at least once. These50 animals were recaptured 111 times, withthe majority (96%)located in the same crev-ices in which they were first captured. Amongmales, larger individuals were recapturedmore frequently. Also, larger males occu-pied the same crevices over a longer timethan did smaller males. Further, observa-tions of 337 males and 216 females indicatethat adult A. aeneus occur singly in rock crev-ices. The spacing of A. aeneus in individualrock crevices and the fidelity of males to spe-cific crevices provides additional evidencefor territoriality in this species.

P2.69CUSACK, B.J.*, NIEWIAROW-SKI,P.H., Community College of AlleghenyCounty, University of Akron, OH. Variation inendurance in the fence lizard, Sceloporusundulatus: the effect of temperature, behav-ior, and morphology.

We measured the thermal sensitivity ofendurance capacity, preferred body tem-peratures, activity body temperatures, andseveral morphological characteristics ofSceloporus undulatus from Nebraska and

Ohio. Overall, S. undulatus from Nebraskahad higher endurance than Ohio S.undulatus. Endurance measured over S.undulatus’ range of field active body tem-peratures was statistically insensitive to tem-perature. Optimal body temperature for per-formance was statistically higher for the Ne-braska population (mean = 31.26 C versus29.86 C). Preferred body temperatures ofboth populations ranged approximately 29-34 C with a mean of 31.5 ± 0.1 C. There wasno difference between populations in the re-lationship between optimal body tempera-tures and preferred body temperatures.There was also no difference between popu-lations in activity body temperatures (NEmean = 33.7 C; OH mean = 33.3 C). A previ-ous study (Balk and Niewiarowski, 1998)found that S. undulatus from NE had lowermaximal sprint speeds than S. undulatusfrom OH. Endurance and maximal sprintspeed therefore appear to tradeoff at thepopulation level between NE and OH. Fur-thermore, adult lizards from NE (high endur-ance, low maximal sprint speed) experiencehigher rates of mortality than adult lizardsfrom OH (low endurance, high maximalsprint speed). This pattern is consistent withthe hypothesis that endurance may be moreimportant than maximal sprint speed in es-caping predators, however there is currentlyno direct evidence to support such an hy-pothesis. More studies are needed to inves-tigate covariation between locomotor per-formance parameters, life history traits andgeographic variation in this species.

71.2 D’AMICO, L.J.*, DAVIDOWITZ, G.,NIJHOUT, H.F., Duke University, Durham,NC, University of Arizona, Tuscon, DukeUniversity, Durham, NC. Body size evolu-tion in a laboratory strain of Manduca sexta:implications for studies in insect physiologyand endocrinology.

The tobacco hornworm, Manduca sexta,has been used as a model organism for thestudy of insect developmental physiologyand endocrinology for more than 30 years.Many of the connections between the growthand the endocrine physiology of the larvawere established through a series of exten-sive studies done in the early 1970’s. The

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present study compares those findings fromthe 1970’s to our current collony when rearedunder identical conditions. We find that lar-vae are much larger now than in the 1970’s,with a corresponding increase in the criticalweight of the larvae. The threshold size fordetermining the final instar has decreased.These changes likely result from evolution-ary processes that occurred while maintain-ing laboratory colonies. Given the use ofmorphological markers in staging larvae forphysiological and endocrine studies, thechanges in developmental characteristicshighlighted here illustrate the need for in-vestigators to determine if their staging tech-niques rely on relationships originally de-scribed in the 1970’s.

50.6 DAHLGREN, T.G., WEINBERG, J.R.,HALANYCH, K.M.*, Woods Hole Oceano-graphic Institution, National Marine Fisher-ies Service, Woods Hole, Woods HoleOceanographic Institution. Phylogeographyof the ocean quahog (Arctica islandica): in-fluences of paleoclimate on genetic diver-sity and species range.

The ocean quahog, Arctica islandica(Linnaeus, 1767), is a commercially impor-tant bivalve found on continental shelvesthroughout much of the North Atlantic. Toassess genetic subdivision in this species,we sequenced 385 nucleotides of the mito-chondrial cytochrome b (cyt b) gene from 83specimens collected from 12 localities be-tween September 1998 and July 1999(based on preliminary data, the Internal Tran-scribed Spacers, ITS, of the nuclear ribsomalrepeat were not useful). The cyt b data de-limited 11 haplotypes with 0.26% - 8.1%nucleotide difference (coded by 36 variablenucleotide positions) among them. Only 3haplotypes were detected in 39 specimenscollected along the USA coastline, com-pared to 5 haplotypes from 9 Icelandic indi-viduals. The western Atlantic populationsranging from Penobscot Bay (Maine, USA)to southern Virginia showed relatively lowdiversity and appeared genetically similarin that region. Based on the presence ofshared haplotypes, AMOVA analyses, andphylogenetic reconstructions, Icelandicpopulations appear to be more genetically

similar to western Atlantic populations thaneastern Atlantic populations. Specimensfrom the Faroe Islands (n=4) show mixedaffinities. These data are consistent with thehypothesis that a warm Holocene climaticoptimum (circa 7500 BP), and not glacialrefugia, shaped the present-day geneticstructure in A. islandica.

22.2 DALEY, M.A., CARD, G., BIEWENER,A.A., Harvard University, Cambridge, MA.Effective mechanical advantage of theguinea fowl hindlimb during steady and vari-able speed running.

Animals live in an unpredictable environ-ment and rarely move at constant speeds.Thus, muscle function under non-steadyconditions (acceleration, deceleration) is acritical component of locomotor system de-sign. Previous studies have suggested that,during steady speed locomotion, musclesfunction primarily to generate the force re-quired to support body weight. However, itis not understood how these force require-ments change during acceleration and de-celeration. In order to address this, we ex-amined changes in the Effective Mechani-cal Advantage (EMA) of the guinea fowlhindlimb using force platform and high-speed video recordings of the bird runningat both steady and varying speeds. LimbEMA, defined as the total muscle force re-quired per unit of ground reaction force, al-lows comparison of muscle force genera-tion requirements during steady running, ac-celeration, and deceleration. We found thatunder all conditions, the majority of muscleforce required to support the body is gener-ated by the knee and ankle extensors, whilethe hip extensors produce less than 10% ofthe total force. EMA distribution among thejoints changes during acceleration and de-celeration, showing the greatest variation atthe knee and ankle. During acceleration,knee extensors produce a greater percent-age of the total muscle force, while duringdeceleration ankle extensors generate themajority of total muscle force. These changesin EMA likely reflect redistribution of forcegeneration to muscles best suited for the pre-vailing locomotor requirements, allowingmore efficient, rapid force generation during

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acceleration, and less costly absorption ofenergy during deceleration. (Supported byNSF IBN 9923699, and a Howard HughesMedical Institute Predoctoral Fellowship)

P1.92DARVEAU, C.-A.*, SUAREZ, R. K.,HOCHACHKA, P. W., University of BritishColumbia, University of California, SantaBarbara, University of British Columbia. Evo-lution of energy metabolism: the case of hov-ering insects.

Hovering insects possess the highestmass-specific metabolic rate ever measuredand are therefore an excellent model to studythe evolution of metabolic pathways in-volved in energy production. We conducteda survey of the maximal activity of severalenzymes as indicators of glycolytic capacity(Hexokinase, Phosphofructokinase), redoxbalance (Glycerol 3-phosphate dehydroge-nase), and mitochondrial metabolism (Cit-rate synthase, Cytochrome c oxidase) in 19species (4 genera) of Euglossine bees ofvarying size (varying from 50 mg to 1 g). Astrong negative allometric relationship wasobserved for the activity of Hexokinase. Theslope was similar to that of the oxygen con-sumption rate previously published for 9species of Euglossine bees, which highlightsthe importance (maybe high control coeffi-cient) of Hexokinase in these insects. Cit-rate synthase activity was also related tobody mass, however, other factors (e.g. phy-logeny) influenced the relationship. We ana-lyzed data using phylogeneticaly indepen-dent contrasts and discuss the metabolic andevolutionary implications of these results.

P3.26DAVIDSON, B.J.*, MOODY, W.,SWALLA, B., University of Washington, Se-attle. Metamorphic competence in the uro-chordates: cloning of a potential competencefactor involved in EGF signaling.

We are interested in elucidating the sig-nals involved in coordinating urochordatepost-larval development. Through sup-pressive PCR subtractions of stagedBoltenia vil losa larval and juvenilecDNAs, we have isolated transcripts dif-ferentially expressed during urochordatemetamorphosis. A transcript homologousto the EGF signaling protein Cornichon

was isolated in a subtraction focused onthe acquisition of metamorphic compe-tence. We have named this transcriptBenjam (Boltenia EGF neighboring/juxtapositioning/activating? molecule). Insitu hybridizations demonstrate thatBenjam is differentially expressed in theanterior papillary region of competentBoltenia larvae. Research in the urochor-date Herdmania curvata has demonstratedthat the anterior papillary region secretesthe EGF protein Hemps, which is both nec-essary and sufficient for the initiation ofmetamorphosis. Cornichon was first iso-lated in Drosophila where it has a role inregulating the EGF signaling involved inestablishing the dorsal/ventral and ante-rior/posterior axis during oogenesis. Re-cent work in yeast has established a rolefor Cornichon in the directed secretion oftargeted vesicles. Our hypothesis is thatexpression of Benjam acts to potentiateHemps signaling thereby allowingBoltenia larvae to respond to metamorphiccues. Further research into this role forBenjam in urochordate metamorphic com-petence will provide insight into the func-tion of Cornichon, which has a crucial butundefined role in EGF signaling. Addition-ally, a better understanding of urochordatemetamorphosis will provide a foundationfor exploring the evolution of metamorpho-sis within the chordates.64.1 DAVIDSON, B.J.*, MOODY, W.,SWALLA, B., University of Washington, Se-attle. Tunicate out of body experiences: ex-tra-somatic cell migration and other insightsand observations on urochordate metamor-phosis.

We are investigating the morphologicalchanges occurring during urochordate meta-morphosis and the hormonal/transcriptionalsignals which coordinate this process. Ini-tially, we have described a series of discretemorphological stages in the tunicateBoltenia villosa during the period of juvenileorgan differentiation (the first two weeks af-ter settlement.) These include a clear pat-tern of body-wall muscular differentiationwhich has been visualized through actinstaining. This post-settlement pattern of dif-ferentiation may be coordinated by thyroid

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hormones, as TH blockers arrest juvenilesearly in development and TH levels may riseat the time when juvenile differentiation isinitiated. We have also used subtractive hy-bridizations of mRNA expressed at times sur-rounding metamorphosis to investigate thedifferential transcription of genes which maycoordinate metamorphic events. This tech-nique has led to the cloning of a variety ofimmunological genes which seem to be tran-scribed around the time of settlement. Thepreviously described migration of blood cellsacross the epidermis into the heamocoel atsettlement may be related to this immuneresponse. Careful observations of this mi-gration has led to the detection of a group ofmesenchymal cells which migrate througha tube connecting the anterior epidermis tothe outside of the juvenile tunic. The func-tion of this extra-somatic migration is cur-rently under investigation. Through the de-tailed investigation of tunicate metamorpho-sis we are hoping to lay the groundwork fora better understanding of life-cycle evolu-tion among the urochordates as well as howtunicate metamorphosis and post larval de-velopment is related to vertebrate embryo-genesis.

P2.78DAVIS, A.P.*, TOBALSKE, B.W., Uni-versity of Portland, OR. Effect of distance onflap-bounding flight performance.

Previous studies suggest that flap-bounding does not offer an aerodynamicadvantage to birds flying at slow speeds.Therefore, we hypothesized that a bird us-ing this flight style should quickly accelerateafter takeoff and maintain or exceed the mini-mum aerodynamically attractive speed forits morphology. To test this idea, we studiedwing and body kinematics in zebra finch(Taenopygia guttata) as they flew 2, 6, or 10m within a flight corridor. Flights were re-corded using high-speed video (250 Hz),and variation in flap-bounding behavior wasmeasured among and within the flight dis-tances. Average horizontal velocity in-creased as total flight distance increased.Our results support our hypothesis for flightdistances greater than 2 m; flight speeds near6 m/s were achieved during the middle of 6-and 10-m flights, and 6 m/s has been sug-

gested elsewhere to be the minimum speedthat would make flap-bounding aerodynami-cally attractive for a zebra finch. Wingbeatfrequency (WBF) and percent time spent flap-ping (%FLAP) varied significantly amongsubsections of 6- and 10-m flights. How-ever, averaging across entire flights, valuesfor these two variables did not change withtotal flight distance. Compared to perfor-mance in a closed-section wind tunnel (at ahigher altitude), zebra finch in free flight at 6m/s exhibit lower %FLAP (50.2 vs. 68.7%)and higher WBF (28.5 vs. 24.3 Hz). Thesedifferences may be due to tunnel effects, thenon-steady nature of relatively short-distanceflight, or variation in air density betweenstudy locations. (supported by Murdock#99153)

P1.67DAVIS, E.C., University of Kansas.Thermal stresses in the intertidal on acornbarnacles (Balanus glandula andSemibalanus cariosus).

Intertidal organisms live in an environ-ment that has large thermal changes throughthe course of the tidal cycle. Acorn barnaclesare found both on exposed rocks and intidepools in the rocky intertidal. The thermalfactors affecting Balanus glandula andSemibalanus cariosus in these two differentintertidal habitats can be approximated froma mathematical heat flux balance model. Theheat flux balance can be used to predictwhich factors most influence the tempera-ture of a barnacle. The heat flux balance foran exposed barnacle on a rock shows thatconduction is an important factor in the ab-sence of evaporation. However, evapora-tion becomes the dominant term when it isadded to the model under measured fieldconditions. Research was supportedthrough a Friday Harbor Laboratories fellow-ship.

37.1 DAVIS, E.S., University of Wisconsin,Madison. Forced copulation as an evolution-ary epiphenomenon.

To date, two general hypotheses regard-ing the evolutionary origin of forced copula-tion (FC) have been proposed. The first andmost widely accepted was proposed byMcKinney et al. (1983), who posited that FC

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serves as a secondary reproductive strat-egy for paired males. Although not essentialto their argument, the implication is that FCbehavior arose as a result of selection forthis behavior. The second, proposed byGowaty & Buschhaus (1999) is the CODEhypothesis for the origin of sexual coercionbehavior in birds. They posit that males cre-ate a dangerous and coercive atmospherefor females such that a femaleís only re-course is to solicit protection from a male inexchange for exclusive access to her for re-production. Thus, they propose that sexualcoercion arose as a mechanism to ensurefemale monogamy. It should be noted thatthese hypotheses are not mutually exclu-sive, as together they argue that FC hasevolved as a polygynous male strategy, whileat the same time helping to insure femalemonogamy. Studies presented here of mal-lards (Anas platyrhynchos) under semi-natu-ral conditions lead me to propose a thirdhypothesis of the origin of FC behavior inwaterfowl. That is, FC is an evolutionaryepiphenomenon that initially arose becauseits underlying mechanism, high male test-osterone (T) level, was sexually selected foranother reason, namely mate guarding be-havior. Note that this hypothesis posits thatselection for mate guarding behavior pre-cedes selection for FC behavior, in directopposition to the CODE hypothesis. Here Iwill review the evidence for this hypothesisand its impact on the other two hypotheses.

65.4 DAVIS, G.K.*, JARAMILLO, C.A.,PATEL, N.H., University of Chicago. Paxgroup III genes and the evolution of insectpair-rule patterning.

We have investigated the expression ofhomologues of the Drosophila Pax group III(PgIII) genes paired (prd), gooseberry (gsb)and gooseberry-neuro (gsb-n) in short germinsects. During Drosophila embryogenesis,prd acts as one of several pair-rule genes todefine the boundaries of future segmentsvia the regulation of segment polarity genes,including gsb. gsb, in turn, regulates gsb-n,a gene expressed later in the developingnervous system. In order to ascertain the rolethese genes play in the segmentation ofshort germ insects, we have taken a two-

pronged approach. First, we have developeda polyclonal antibody which crossreacts notonly to the products of the three fly genesbut also to the homologous proteins of otherinsects. Using this antibody, we show thatthe embryonic expression of presumptivePgIII orthologues in the flour beetle Triboliumclosely mimics the pattern in Drosophila.Second, we have isolated cDNAs of two PgIIIorthologues from embryos of the grasshop-per Schistocerca. Using both the cDNAs andthe polyclonal antibody, we show that bothgenes are expressed in ectodermal stripeswhose timing and appearance support a rolefor these genes in both defining and pat-terning segments. After the appearance ofstripes of the segment polarity geneengrailed (en), both are expressed in coin-cident stripes of a one-segment periodicity.In a manner reminiscent of gsb and gsb-n,each of these stripes is restricted to the neu-roectoderm and lies just anterior to its corre-sponding en stripe. Prior to the appearanceof en, however, one of these genes is ex-pressed in stripes of a two-segment period-icity before maturing into its segmental pat-tern. This early expression is more reminis-cent of prd and provides for the first time evi-dence that pair-rule patterning is a facet ofgrasshopper segmentation.

8.4 DAVIS, M.C.*, SHUBIN, N.H.,DAESCHLER, E.B., University of Chicago,University of Chicago, Academy of NaturalSciences of Philadephia. The evolution ofthe endochondral and dermal skeleton infins and limbs.

The paired appendages of the two majorclades of bony fish, actinopterygians andsarcopterygians, are composed of two sepa-rate skeletal units: A proximal endochondralskeleton and a more distal dermal skeleton.The relative contribution of these skeletalcomponents to the fin is one of the key mor-phological differences between ray-finnedand lobe-finned designs. Shifts in the pat-tern and development of each of these skel-etal units can affect the function of the ap-pendage as a whole. However, studies ofthe development of living fish cannot tell thewhole story. Fossils reveal intermediate de-velopmental and functional conditions that

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would not be predicted from a knowledge ofrecent taxa alone. Newly discovered fossilsof the Devonian sarcopterygian Sauripterusshow an extremely limb-like endochondralskeleton that is sandwiched between mas-sive unjointed dermal rays. The endochon-dral elements of Sauripterus correspond inposition to both the digits and mesopodiumof tetrapods. The biomechanical function ofthe digit-like elements in Sauripterus islinked with the dermal skeleton; most move-ments of the fin would rely on the function ofboth skeletal components. This situation dif-fers greatly from that seen in the earliest tet-rapods. Tetrapods lack the dermal rays and,consequently, the digits interact directly withthe substrate. Indeed, one of the main shiftsin the origin of tetrapods may not be the ori-gin of the autopodial bones, per se, but theloss of the dermal radials. This suggeststhat the loss of the dermal skeleton in ap-pendage development is correlated with theevolution of mechanisms that patterned pre-existing endochondral elements as an in-dependently varying unit.

P1.94A DE LA PAZ, K.L., HOYT, D.F.,WICKLER, S.J., COGGER, E.A., CaliforniaState Polytechnic University, Pomona. Doesmuscle function explain preferred speed?

Horses prefer to trot at speeds that arethe most economical. A possible explana-tion for this preference is at these speeds,muscle fibers are contracting more slowlyand functioning more economically. Thepresent study was undertaken to test thehypothesis that the lateral head of the tri-ceps, an elbow extensor, shortens less, ormore slowly, at preferred trotting speed thanat those speeds above and below preferredtrotting speed. Muscle length changes weremeasured using sonomicrometry and ana-lyzed during the portion of stance phasewhen EMGs indicated the muscle was ac-tive and during which time there was an ex-tensor moment at the elbow. Three Arabianhorses (4-7 years old) were trotted at speedsfrom 2.5-4.5 m/s. Total positive strain (muscleshortening) and average positive strain rate(velocity of muscle shortening) were calcu-lated at each speed. Total positive strain av-eraged 12% and showed no significant re-

lationship with speed (R2=0.01, P>0.05).There was a positive linear relationship be-tween speed and average positive strain ratein two of the three horses studied (R2=0.64and 0.87, P<0.05). This increase in averagepositive strain rate resulted from a de-creased time of contact. These observationsare inconsistent with the proposed hypoth-esis. Supported by NIH 1 S06 GM53933.

44.6 DEAROLF, J.L.*, MCLELLAN, W.A.,PABST, D.A., HERMANSON, J.W., CornellUniversity, UNC Wilmington, UNCWilmington, Cornell University. Diaphragmmuscle development in bottlenose dolphins(Tursiops truncatus).

Being born directly into an aquatic en-vironment creates unique challenges forthe breathing muscles of neonatal ceta-ceans. Not only must these muscles beactive at the instant of birth to allow for gasexchange, but their activities must also becoordinated such that breathing takesplace at the surface. Thus, we hypothesizethat the breathing muscles of bottlenosedolphins, represented in this study by thediaphragm, will demonstrate adult mor-phologies at birth, as measured by the his-tochemical (myosin ATPase) and bio-chemical activities of their componentmuscle fibers. The fiber-type profiles ofadult (64% slow-twitch) and neonatal(33% slow-twitch) dolphin diaphragms arefound to be statistically different (F=48.02,p=0.002, df=5, n=6). In addition, there is astrong positive correlation (R-sq=0.98)between the fiber-type profile (percentslow-twitch fibers) of the dolphin dia-phragm and total body length (TBL), a char-acter that is used as a relative measure ofage in dolphins. The results of the bio-chemical analyses support the correlationbetween fiber-type profile and TBL, dem-onstrating an increase in the expressionof slow (type I) myosin heavy chainisoform with increasing body length. Thus,the diaphragms of neonatal dolphins arenot well developed at birth (92-132 TBL).However, as the dolphin grows and in-creases its swimming and diving activities,the diaphragm matures and achievesadult morphology. Therefore, unlike dol-

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phin locomotor muscles, which are welldeveloped at birth, the diaphragm re-quires an extended period of postnatal de-velopment to achieve the adult fiber-typeprofile.

S3.4 DEBAN, S.M.*, O’REILLY, J.C.,NISHIKAWA, K.C., University of Utah, SaltLake City, University of Massachusetts,Amherst, Northern Arizona University, Flag-staff. The evolution of the motor control offeeding in amphibians.

We compared prey capture among sala-manders, frogs and caecilians in a phylo-genetic context to identify major evolution-ary transitions of the motor control of am-phibian feeding. The common ancestor ofliving amphibians was most likely a preda-tor with a free-living aquatic larval life stage.A combination of visual, olfactory, tactileand lateral line (in water) cues triggeredfeeding. Suction feeding was used in wa-ter and jaw prehension on land. Feedingkinematics were influenced by both feed-forward and feedback information. Theprimitive feeding behavior of salamandersmost resembles that of this theoretical an-cestor. Derived conditions within sala-manders include 1) the evolution of elabo-rate, visually-controlled tongue protractioncorrelated with decreased lunging and 2)the reduction of vision in some groups andthe concomitant dominance of othersenses in triggering and modulating feed-ing. In the common ancestor of frogs, thetongue was short and lunging was neces-sary for prey capture. The visual systemdominated other senses in triggering andmodulating feeding and ampullary organswere lost, precluding the use of electricalcues. Derived conditions in frogs include1) the repeated evolution of long tongueswith a correlated decreased in lunging and2) the dominance of olfactory and tactilesensory modalities in many burrowing,termite-eating species. Metamorphosedcaecilians still use jaw prehension to cap-ture prey. The ability to form visual imageswas lost ancestrally, as was the role of vi-sion in feeding. Thus, the extensive varia-tion seen in caecilian feeding kinematicsis apparently driven by olfactory and tac-

tile cues. Derived conditions among cae-cilians include the apparent use of electri-cal cues during feeding in aquatic species.

46.2 DEMAINTENON, M.J., University ofHawaii, Hilo. Patterns of reproductive sys-tem development in the caenogastropods;systematic and evolutionary implications.

The reproductive system is one of themost complex and variable of gastropod or-gan systems, and is often also the last organsystem to develop. The level of anatomicalvariation of the reproductive system, coupledwith its late development, renders it an inter-esting system to investigate for evolutionarychanges in organogenetic patterns. Patternsof reproductive system organogenesis arecompared in several representativecaenogastropod species, relative to exist-ing hypotheses of caenogastropod evolu-tion. I am primarily interested in two ques-tions: 1) How much temporal variation docaenogastropod taxa exhibit in the repro-ductive organogenetic sequence; and 2)How are patterns of temporal variation inthe organogenetic sequence related to quali-tative variations in adult reproductiveanatomy between caenogastropod taxa?Paedomorphotic heterochronic events arethought to be common in gastropod evolu-tion, however this hypothesis has been diffi-cult to test. Comparison of organogenetic se-quences within a phylogenetic frameworkallows the predominance of different typesof heterochronic patterns to be addressed.

27.5 DEMES, B.*, CHIU, J., TRUONG, C.,QIN, LARSON, S., SUNY Stony Brook. Therole of the primate fibula in weight-bearingof the leg.

Among mammals, primates have rela-tively robust fibulae. We investigated the roleof the primate fibula in weight-bearing in anin vitro study of the deformation of the twoleg bones in a chimpanzee, baboon andhuman. Three rosette strain gauges wereattached around the midshaft of the tibia andfibula in a leg preparation with muscles re-moved, but ligaments and joints intact. Thelegs were loaded in compression throughthe knee and ankle joints. The proximal fe-mur was held upside down in a clamp, and

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the foot was tied to a plate that was subse-quently loaded with weights. Loading cycleswere repeated after cutting of the in-terosseous membrane, the proximal ti-biofibular ligaments, and, ultimately, thefibula. In all three species, the predominantloading regimes for both bones is bending.In general, strains increase in the tibia anddecrease in the fibula after cutting of soft tis-sues connecting the two bones. The changesin strain following cutting of the interosseousmembrane are insignificant. Cutting of theligaments has more of an effect. Strains in-crease incrementally and significantly in thetibia when the fibula is cut. In addition, theneutral axis of bending rotates from amediolateral to a more oblique position. Thedescribed changes are more dramatic in thenonhuman primates. In comparison to hu-mans, these species have more robust fibu-lae that are sandwiched beneath a flange ofthe tibial plateau rather than being attachedto the lateral side of the tibia as in humans.These results indicate that the fibula has asignificant role in weight-bearing of the legin primates, that the interosseous membraneis probably unimportant in weight transferbetween the two leg bones, and that inter-specific differences in bone size and posi-tioning correlate with the observed strainpattern.

S14.3DENVER, R.J., University of Michigan,Ann Arbor. Transcriptional regulatory net-works induced by thyroid hormone duringmetamorphosis of the amphibian centralnervous system.

Thyroid hormone (T3) induces multiplemolecular, biochemical and morphologicalchanges in the tadpole CNS. These changesprepare the animal for the transition fromlarval to adult life. At the cellular level, T3-induces cell proliferation, death, migration,process-elaboration and differentiation. To-wards understanding the molecular basisfor T3 action on the tadpole brain we isolatedseveral genes that are directly regulated byT3 in Xenopus laevis. Ongoing sequenceanalysis places these genes into 6 generalcategories: 1) transcription factors, 2) cellu-lar enzymes, 3) structural proteins, 4) cellcycle control proteins, 5) membrane recep-

tors, 6) secreted signaling molecules. Weanalyzed the function of several immediateearly genes that code for transcription fac-tors. For example, mRNA for the basic tran-scription element binding protein (BTEB) isstrongly induced by T3 in the premetamor-phic tadpole brain. Brain BTEB mRNA levelrises during metamorphosis and this risedepends on T3. BTEB mRNA expression inthe adult brain is low and generally inde-pendent of T3. The gene is most highly ex-pressed in the subventricular zone of thetelencephalon, regions of the diencephalonand deep cellular layers of the tadpole tec-tum. We showed that Xenopus BTEB, likemammalian BTEB, binds to GC rich se-quences and activates transcription frompromoters containing multiple GC boxes.BTEB overexpression and misexpressionstudies in frogs and rodents suggest a rolefor this protein in neurite outgrowth andbranching. This and other T3-inducible tran-scription factors likely play critical roles inthe signal transduction pathways leading tothe diverse changes in the tadpole CNS dur-ing metamorphosis. (supported by NSFgrant IBN9724080)

S9.10DENVER, R.J., University of Michigan,Ann Arbor. Evolution of the corticotropin-re-leasing hormone signaling system and itsrole in stress-induced developmental plas-ticity.

Post-embryonic development can bestrongly influenced by the external environ-ment. Amphibian tadpoles show strong re-sponses to environmental signals, exhibit-ing continuous variation in the timing of meta-morphosis. The most important environmen-tal variable for a tadpole is water availability.We analyzed the ecological and physiologi-cal bases for the timing of metamorphosis intadpoles exposed to habitat desiccation.Tadpoles of several species have beenshown to accelerate metamorphosis whentheir ponds dry. Our ecological studies sug-gest that tadpoles use special senses todetect deleterious changes in their larvalhabitat. Habitat desiccation results in theprecocious activation of the thyroid and theinterrenal axes, the hormones of which drivemetamorphosis. Several lines of evidence

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suggest that a common neuroendocrine sig-naling pathway involving the stress neu-ropeptide corticotropin-releasing hormone(CRH) determines the activation of the twosystems. A role for CRH in regulating thepituitary-thyroid axis in addition to the pitu-itary-adrenal (interrenal) axis has been dem-onstrated in representatives of all vertebrateclasses except mammals. The CRH signalis transduced by at least two receptor sub-types and may be modulated by a secretedbinding protein. Taken together with ecologi-cal findings, our data suggest that tadpolescan respond adaptively to environmentaldeterioration by mounting a classical neu-roendocrine stress response. Evolutionaryconservation of the role of CRH in mediat-ing developmental plasticity is suggested byrecent demonstrations in mammals that CRHof fetal and/or placental origin determinesthe length of the gestational period and maybe involved with precipitating preterm birth.(Supported by NSF grant IBN9974672)

42.2 DESROCHERS, D.M.*, NISHIKAWA,K.C., Northern Arizona University, Flagstaff.Hypoglossal sensory feedback control dur-ing feeding in the toad, Bufo alvarius.

This study explores the role of hypoglos-sal sensory feedback during feeding in thetoad Bufo alvarius. Prior studies indicate thatsensory feedback from the hypoglossalnerves can trigger inhibition of both tonic andphasic activity of the jaw levator muscles.Temporary inhibition of the jaw levators al-lows the jaw depressors to produce rapidmouth opening. Following bilateral hypo-glossal transection, the levators and depres-sors fire simultaneously, preventing mouthopening during feeding attempts. Utilizingunilateral rather than bilateral hypoglossaltransections, coupled with high-speed digi-tal videography and EMG recordings fromthe jaw levators and depressors, I have fur-ther investigated hypoglossal feedback con-trol of the anuran jaw musculature. Prelimi-nary data show that while the mouth opensfollowing unilateral transection, the velocityof mouth opening and the maximum gapeangle are reduced. These results suggestthat transection of the hypoglossal nerve onone side prevents the inhibition of tonic and

phasic activity of the jaw levators only onthat same side. Hence, on that side of thejaw, the levators and depressors may be fir-ing simultaneously, resisting the efforts of thecontralateral depressors to open the mouthand therefore reducing the speed and maxi-mum gape angle of mouth opening. Accord-ing to this scenario, each hypoglossal nervecarries information back to the central ner-vous system in a unilateral fashion. Nervestaining studies are currently being con-ducted to further test this hypothesis.

43.3 DEUFEL, A.*, CUNDALL, D., LehighUniversity, Bethlehem, PA. Feeding in stilettosnakes.

Stiletto snakes (Atractaspis) resemblevipers in having a short maxilla bearing along fang associated with a large venomgland. Previous studies of Atractaspis havedescribed an unusual envenomation strat-egy in which one fang is unilaterallyeverted from the closed mouth andstabbed into the prey by a posteroventraljerk of the head. Prior anatomical descrip-tions suggest that the head of Atractaspisis designed for increased cranial kinesisthrough liberation of both ends of the ptery-goid. We combined video records of A.bibroni feeding on live prey inside a nar-row tunnel with electrical stimulation ofanesthetized snakes and dissection of pre-served specimens to show that the appar-ent design for increased cranial kinesis isconstrained minimally by maxillary-pre-frontal relationships that limit pterygoidmovement. Liberation of the palatine fromthe pterygoid precludes prey transportusing the “pterygoid walk” because of theabsence of a palatine protraction mecha-nism. Atractaspis has to rely on a relativelyinefficient transport mechanism in whichthe snake forces its head over the preywith lateral rotations around a vertical axis.As the prey enters the esophagus A.bibroni switches to bilateral head and an-terior trunk extension and compression, amechanism that can make use of the pa-latine teeth. It remains unresolved how anupper jaw with high kinetic potential of themedial elements could evolve togetherwith a lateral upper jaw with limited kinetic

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potential. Nevertheless, the unusual feed-ing apparatus of Atractaspis appears tobe ideally suited for prey capture in smallspaces.

54.1 DEVRIES, A.L.*, CHENG, C.-H.C,University of Illinois. Freezing avoidancestrategies differ in Antarctic and Arctic fishes.

Notothenioid fishes in Antarcticafreeze at approximately -2.3oC. One de-gree of this freezing point depression isprimarily due to NaCl, while the remain-der is due to antifreeze glycoproteins(AFGP) and a recently discovered anti-freeze potentiating protein (AFPP). AFGPsare present in the blood at 30 to 40 mg/mlwhile AFPP ranges from 2 to 4 mg/ml de-pending on the species of notothenioid.Only the antifreeze activity of the largerAFGPs 1-5 appeared to be potentiated,while the smaller AFGPs 7 and 8 are not.Thus fishes living in very icy shallow wa-ter like Pagothenia borchgrevinki havelower levels of AFGP 1-5 and high levelsof AFPP, while Trematomus loennbergi liv-ing at 500 meters where the cold waterlacks ice have high levels of AFGP 1-5and low levels of AFPP. This relationshipappears to correlate with depth and theamount of ice in the fishes environment.Arctic gadid fishes have freezing pointsbetween -1.9 and -2.1oC in the winter andalso have AFGPs similar in size, composi-tion and amount to the notothenioids butthey do not have AFPP. There is no evi-dence of any other macromolecular anti-freeze compound and thus the slightly el-evated blood salt concentrations and theAFGPs appear to account for their lowfreezing points and freezing avoidance. Incontrast, in the Antarctic notothenioids, thecombination of elevated salt concentration(250mM), AFGPs and AFPP is responsiblefor the freezing avoidance.

S9.11DHABHAR, F.S., Ohio State Univer-sity. Stress and the augmentation of immunefunction.

Stress may be defined as a sequenceof events, that begins with a stimulus(stressor), that is recognized by the brain(stress perception), and which results in

the activation of physiologic systems withinthe body (stress response). Many evolu-tionary selection pressures are stressors,and one of the primary functions of thebrain is to perceive stress, warn the bodyof danger, and enable an organism to re-spond. We hypothesized that under acuteconditions, just as the stress response pre-pares the cardiovascular and musculosk-eletal systems for fight or flight, it may alsoprepare the immune system for challenges(e.g. wounding) which may be imposed bya stressor (e.g. an aggressor). Initial stud-ies showed that acute (2h) stress induceda significant trafficking of immune cells tothe skin. Since the skin is an organismísmajor protective barrier, we hypothesizedthat this leukocyte redistribution may serveto enhance skin immunity during acutestress. We tested this hypothesis using thedelayed type hypersensitivity (DTH) reac-tion, which mediates resistance to variousinfectious agents, as a model for skin im-mune function. Acute stress administeredimmediately before antigen exposure sig-nificantly enhanced skin DTH. Adrenalec-tomy (ADX) eliminated the stress-inducedenhancement of DTH while administrationof physiological doses of corticosteroneand/or epinephrine to ADX animals en-hanced skin DTH in the absence of stress.These studies showed that changes in leu-kocyte distribution and circulating stresshormones are global mediators of theimmunoenhancing effects of acute stress.We recently identified gamma interferonas a local cytokine mediator of a stress-induced immunoenhancement. Our resultssuggest that during acute stress the brainsends preparatory warning signals to theimmune system just as it does to other fight/flight systems of the body.

S11.7DIAL, K.P., WARRICK, D.R.*,BUNDLE, M.W., University of Montana, MinotState University. Stability and maneuverabil-ity in avian flight: keeping a steady head witha thrashing body and a twisted neck.

Popular models of avian maneuverabil-ity based on steady-state assumptions andparameters such as wing loading fail to de-scribe the full ecological and evolutionary

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import of maneuvering performance, par-ticularly during low speed, flapping flight.Previous studies revealed that in this keyflight regime maneuvering is saltatory, andinvolves authoritative use of velocity-gener-ated force asymmetries developed duringflapping. The effectiveness of this mecha-nism in maneuvering is largely independentof wing loading; however, low wing loadingwould result in reduced stability in turbulentconditions. Thus, the quick use of strongaerodynamic forces, as well as the gyro-scopic action of flapping wings are likely im-portant factors for maintaining stability, es-pecially for small, lightly wing-loaded birds.Equally important may be a bird’s ability tospare its head from the repeated shocks ofsaltatory locomotion. Data from x-ray film ofmagpies in wind tunnels, and light film ofpigeons recovering from handler-inducedrolls shows that birds isolate their visual andvestibular systems, presumably via cervicalreflexes, from the vertical movement and ac-celerations of the body during flapping flight,and the angular movement and accelera-tions occurring during rolling maneuvers. Pi-geons equipped with neck braces that re-duced their head’s normal three-hundreddegree range-of-rotation to thirty degreesrefused to or could not fly; pigeons with headmovement restricted to seventy degrees haddifficulty maintaining equilibrium and recov-ering from handler-induced banks. The neu-ral integration of visual, vestibular, and prop-rioceptor inputs required for the control ofmaneuvering and maintenance of straightand level flight has not been extensivelystudied, although such integration must havebeen an essential step in the evolution offully volant species.

22.3 DIAL, K.P., University of Montana. Onthe origin and ontogeny of bird flight: devel-oping wings assist vertical running.

Discussions on the origin of avian flightfall into two philosophical camps: arboreal(tree-down) or cursorial (ground-up) hypoth-eses, both of which are dominated by pale-ontological evidence that fails to adequatelyaddress logical incremental adaptive stagesnecessary to achieve fully developed flightmechanics. Here, I present a new model

based on novel behavioral and morphologi-cal data obtained during post-hatching de-velopment of precocial gallinaceous birds.This model offers a solution to the impasseof previous scenarios on the origin of avianflight and differs from the traditional cursorialthesis. Daily progress of locomotor perfor-mance (e.g., vertical and horizontal accel-erations of flight and terrestrial locomotion)and morphometrics of wing development(e.g., wing loading, feather growth) of threespecies (Chukar Partridge, n=10; JapaneseQuail, n=10; and Ring-necked Pheasant,n=2) from hatching to adult stage were ob-tained using high-speed video (60-250 Hz)and Doppler radar. To escape beinghandled, even one-day-old chicks exhibitedthe following locomotor behavior: theyjumped vertically, vigorously beat their feath-erless forelimbs, and surprisingly swung theirhind limbs through an arc similar to that usedduring over-ground running. Throughoutdevelopment partially formed wings developsignificant aerodynamic forces that assist thelegs. This enables birds to “run vertically”achieving substantial heights against roughsurfaces such as rocks, cliffs, and tree trunks.This “Assisted Vertical Running Hypothesis”appears consistent with evidence from fos-sil data and provides incremental adaptiveplateaus, as revealed by ontogenetic trajec-tories, necessary to achieve fully developedavian flight mechanics as observed in livingspecies.

51.5 DICKEY, B., University of Kentucky.Prediction and description of interaction pat-terns in social dominance structures.

Though social dominance hierarchieshave been demonstrated and studied in awide variety of vertebrate and invertebratetaxa, no models exist that explain or predictwhich animals should interact aggressivelywithin a hierarchy. Data from empirical stud-ies of social dominance are often presentedin matrices that summarize which animalwon the interactions between each pair ofindividuals. Many of these matrices containidentifiable patterns of interactions; for in-stance, interactions may be clustered alongthe diagonal of the matrix suggesting thatindividuals prefer to interact with others of

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equivalent rank. I present a game theoreticmodel that predicts this and other patterns,depending on the differences in benefits be-tween different ranks in the hierarchy, andthe distribution of traits that signal resourceholding potential between individuals. Thepredicted patterns are then compared toempirical data using a statistical approachthat permits comparison of matrices. Thiscomparison improves our understanding ofthe link between social structure, benefits ofrank, and traits that signal resource holdingpotential in natural groups.

S11.10 DICKINSON, M.H., University ofCalifornia, Berkeley. The structure and func-tion of flight trajectories in freely-flying fruitflies.

Without buoyancy or a solid horizontalplane for support, stability is of crucial im-portance to flying animals. Further, for ani-mals that rely on spatially complex sensorycues for food search, mating, or predatoravoidance, stability is required not only tokeep the locomotor machinery in an appro-priate orientation, but also to keep body os-cillations from contaminating sensory sig-nals. My laboratory has been studying theflight behavior of fruit flies, highly maneu-verable organisms that rely on rapid sen-sory-motor feedback, and not passivemechanisms, for their robust stability. Theflight paths of fruit flies consist of straight se-quences interspersed with rapid saccadicturns, during which the animal quicklychanges its heading by roughly 90 degrees.While flies are thought to rely heavily on vi-sual feedback in flight control, evidence sug-gests that during the straight flight sequencesthey fly under the exclusive control of theirhalteres, mechanosensory structures that actas an inertial guidance system. Sincemechanosensory cells are capable of fasterresponse dynamics than photoreceptors,feedback from the halteres can tune the sta-bility reflexes much more sharply than couldfeedback from the eyes. The saccades ap-pear to represent fixed action patterns, themagnitude of which does not depend uponprior visual experience. The visual systemdoes, however, determine the direction andtiming of saccades. During straight flight, the

visual system appears to integrate optic ex-pansion, triggering a collision avoidancesaccade when the expansion reaches a criti-cal threshold. The role of the straight flightsequences may be to stabilize gaze duringthis integration process in order to minimizethe errors introduced by body oscillations.Thus, the involuntary inertial stability sys-tem may play an important role in voluntary,visually-guided behaviors.

17.2 DINKELACKER, S.A.*, WILSON, T. P.,HOWARD, J. H., Frostburg State University,George Mason University, Humboldt StateUniversity. Spatial ecology of syntopic bog(Clemmys muhlenbergii), spotted (Clemmysguttata) and snapping (Chelydra serpentina)turtles in Maryland.

I examined differences in home rangesamong syntopic species of turtles occurringwithin a 3-ha wetland in Carroll County, Mary-land. I attached radio transmitters to the cara-paces of bog (Clemmys muhlenbergii), spot-ted (Clemmys guttata), and snapping turtles(Chelydra serpentina) and located each in-dividual twice a week during the summer of1999. I compared minimum convex poly-gon and adaptive kernel home-range sizeestimates and average daily movementsamong species using one-way ANOVA. Iplotted all home ranges for each individualof all three species to assess total area usedand spatial overlap within and among spe-cies. Spotted turtles had significantly largerhome ranges than bog and snapping turtles.Spotted turtles had significantly greater av-erage daily movements than bog turtles butnot snapping turtles. Home ranges of bogturtles exhibited the greatest amount of in-traspecific overlap (75.1%) and those ofsnapping turtles the least (15.4%). Spottedturtles overlapped the majority of the totalarea used by bog turtles (79.6%) and snap-ping turtles (64.4%). Interestingly, bog turtlesonly overlapped 19.5%, and snapping turtlesonly overlapped 8.0% of the total area usedby spotted turtles. Comparisons of home-range sizes, avaerage daily movements andspatial overlap among the three speciessuggest that spotted turtles require morespace to suport resource requirements atthis site.

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P3.36 DIOGO, R.*, OLIVEIRA, O.,PARMENTIER, E., CHARDON, M.,VANDEWALLE, P., University of Liëge,Belgium. The origin and transformation ofcatfish (Teleostei: Siluriformes) palatine-maxillary system: an example of adaptivemacroevolution.

The adaptive value of siluriform barbelsin muddy waters dwellers and nocturnalfish is evident and was moreover demon-strated experimentally. The maxillary onesare characterized by their connection to amobile mechanism, the palatine-maxil-lary system (PMS), which is constitutedby the maxillary, the palatine and more orless specialized ligaments and musclesresponsible for their movements.Siluriform sister-groups (Gymnotiformesand Characiformes) do not have barbelsat all and do not present any structure pre-figuring barbels, particularly the maxillarybarbels, which are the only ones presentin the most primitive catfishes, thediplomystids. In fact, catfish PMS is basedon two basic siluroid synapomorphies: 1)a skeletal uncoupling between the pa-latine bone and the the rest of the suspen-sorium; 2) a muscular uncoupling of theadductor arcus palatini, leading to the dif-ferentiation of the extensor tentaculimuscle, which is associated with the ab-duction of the maxillary barbel. So, unlessimprobably well preserved fossils wouldbe described in the future, a gap will re-main between the diplomystids and thegymnotiforms and characiforms. However,departing from the Diplomystidae, itseems possible to follow evolutionary linesleading to more specialized PMS types.Our study focus precisely on the evolutionof the PMS among catfish. For each mor-phological transformation, the way it wasrealized is hypothetized and the probableadaptive advantage it brings is analysed.

P1.55DOELLER, J.E.*, KRAUS, D.W., Uni-versity of Alabama at Birmingham. Sulfide-mediated feedback inhibition of endogenoussubstrate oxidation in Geukensia demissagill mitochondria.

Gill mitochondria from Geukensiademissa, a marine mussel from high sulfide

sediments, exhibit sulfide-supported respi-ration with an ADP/O ratio near one. In vivo,sulfide-mediated gill oxygen consumptionis three times higher than control at the sameciliary beat frequency, consistent with achange in mitochondrial ADP/O ratio from 3to 1, and suggesting a change in substrateuse from endogenous carbon to sulfide.Carbon-supported mitochondrial respirationdeclined incrementally following successivesulfide additions, suggesting possible inhi-bition of endogenous substrate oxidation byendproducts of sulfide metabolism. Thesenumerous endproducts include thiosulfateand sulfite. Although thiosulfate alone hadlittle effect on mitochondrial respiration,sulfite appeared to lower both state 3 andstate 4 respiration. Therefore, mitochondrialsubstrate use may be subject to feedbackcontrol by sulfide metabolic endproducts.Supported in part by NSF IBN9219658 andIBN9728409.

P1.19DOUGHERTY, B.E*, MCNAMER, A.N.,CROCKETT, E.L., Ohio University, Athens.Inverse compensation for fluidity in mito-chondrial membranes from thermally accli-mated earthworms.

Exposure to low temperature typicallyresults in changes at many levels of biologi-cal organization including adjustments inboth chemical and physical properties of bio-logical membranes. We compare membranefluidities in enriched mitochondrial prepara-tions from the body wall of the earthworm(Lumbricus terrestris) after four weeks ofacclimation to 5 and 15oC. Membranes from5oC-acclimated worms are more orderedthan membranes from 15oC-acclimated ani-mals with significantly greater polarizationvalues at all but one temperature measuredwith the fluorescent probe DPH. At physi-ological temperatures polarization valuesare 0.22 and 0.15 for 5- and 15oC-acclimatedworms, respectively. Although reports of in-verse compensation of fluidity (greater mem-brane order in cold-bodied animals com-pared with warm counterparts) are relativelyrare, inverse compensation in the earth-worm is accompanied by changes in themetabolic status of the animal. Supported,in part, by the Honors Tutorial College at OhioUniversity.

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S6.8 DRUCKER, E.G., University of Cali-fornia, Irvine. Experimental hydrodynamicsof fish locomotion: functional insights fromwake visualization.

The fins of fishes are sophisticated con-trol surfaces that play important roles in sta-bilization and propulsion of the body duringlocomotion. Despite a century of active in-vestigation into the mechanisms of fin func-tion, there remains one critical area in whichprogress has been limited: analysis of thephysical interaction between the animalíspropulsor and the aquatic medium. This pa-per reviews current biomechanical researchemploying a new flow visualization tech-nique, digital particle image velocimetry(DPIV), adopted from the field of fluid me-chanics. This method allows experimentalmeasurements of water velocity flows in thewake of freely swimming animals, andthereby enables direct investigation of thehallmark of fluid force production (vorticity).Emerging from recent applications of DPIVin research on fish swimming are findingswith general significance for the study ofaquatic locomotion: (1) DPIV is an effectivetool for measuring the reaction forces onswimming animals. From rates of momen-tum transfer and vortex geometry, both themagnitude and orientation of wake forcescan be determined to gain insight into themechanisms of propulsion. (2) Three-dimen-sional analysis of wake flow is critical. Flowpatterns in perpendicular sections of thewake reveal a hydrodynamic force balanceon steadily swimming fish, a result validat-ing the DPIV approach. (3) Fishes can ad-just the structure and strength of their wakein response to varying locomotor demands.Multiple fins are employed simultaneouslyand independently to control locomotor forceduring both unsteady maneuvering andsteady swimming across a range of speeds.For future work, DPIV holds considerablepromise for illuminating the dynamics of bio-logical fluid flow and for allowing functionalinterpretation of evolutionary trends inpropulsor design.

2.4 DRUCKER, E.G.*, LAUDER, G.V.,University of California, Irvine, Harvard Uni-versity, Cambridge, MA. Function of the te-leost dorsal fin: experimental analysis ofwake forces in sunfish.

A major structural transformation charac-terizing the evolution of teleost fishes is theelaboration of the dorsal fin into anteriorspiny and posterior soft-rayed portions. Asyet, however, there are no hydrodynamicdata on the functions served by these dis-tinct fin surfaces. In order to initiate study ofthe locomotor repertoire of the teleost dor-sal fin, we examined the wake of bluegillsunfish (Lepomis macrochirus) duringsteady swimming at low and high speeds,and while turning in response to a visualstimulus. Patterns of water flow within fron-tal-plane sections of the dorsal fin wake weremeasured using digital particle imagevelocimetry (5 W laser, 250 Hz video fram-ing rate) and locomotor forces were esti-mated from rates of momentum transfer. Forfish 21 cm in length (L), neither the spiny norsoft dorsal fins shed detectable vorticity at0.5 L/s, indicating that they do not play anactive role in propulsion at this low speed. Athigher speeds, however, the dorsal fin is re-cruited to supplement locomotor forces ex-erted by the pectoral and caudal fins. At 1.1L/s, continuous oscillation of the soft dorsalfin introduces paired counterrotating vorti-ces into the wake. The thrust associated withthe dorsal finís momentum jet is on average24% of the total thrust developed by all fins.During turning maneuvers, the soft dorsalfin exerts laterally oriented forces that ex-ceed thrust forces by a factor of 1.7 on aver-age. The dorsal fin, therefore, plays propul-sive roles both in translating the body dur-ing steady swimming and in exerting torquearound the bodyís center of mass duringunsteady locomotion. This study documentsthe ability of teleost fish to use simultaneous,independent action of multiple fins for thecontrol of vorticity and for the modulation oflocomotor force.

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P3.37DRUZINSKY, R.E., Governors StateUniversity, IL. Sciuromorphy andprotrogomorphy in extant and fossil rodentia.

It has long been recognized thatsciuromorphy, in which the anterior lateralmasseter muscle originates from an ex-panded bony plane on the rostral surfaceof the anterior root of the zygomatic arch,evolved more than one time during the evo-lutionary diversification of rodents. Argu-ments for multiple origins of thesciuromorphic condition are usually basedon the necessity of deriving sciuromorphyindependently in disparate clades withinthe Rodentia. However, it is clear that care-ful study of the masticatory apparatus alsodemonstrates that sciuromorphy in theSciurids is anatomically different fromsciuromorphy in Geomyids. Anatomicalstudy of Aplodontia, the only extantProgtrogomorph, indicates that Aplodontiashares charaters of the jaw musculaturewith the Sciurids that it does not share withthe Geomyids. Examination of early ro-dents also demonstrates that more thanone type of sciuromorphy andprogtrogomorphy may be found in thefossil record. Oligospermophilus andCedromus are fossil sciurids that, as de-scribed by Korth and Emry (1991) exhibita “unique zygomatic structure” in-be-tween sciuromorphy and protro-gomorphy. These specimens clearlyhave attachment areas for the superfi-cial masseter and lateral masseter simi-lar to those of the Aplodontia/Sciuridclade. In contrast, the Eocene rodentSciuravus nitidus, which has been de-scribed as a primitive sciuromorph orprotrogomorph (Dawson, 1961), has at-tachment areas for the masseter musclesthat are distinctly different from theAplodontia/Sciurid clade, and more simi-lar to the extant Dipodoids. Thus, anatomi-cally there is more than one kind ofsciuromorphy and even more than onekind of protrogomorphy. And classicprotrogomorphy, as found in Paramys andAplodontia, is probably primitive only forIschyromyids, Sciurids, and Aplodontids.

P2.88A DRUZISKY, K.*, BRAINERD, E.L.,University of Massachusetts. Buccal oscilla-tion in the aquatic turtle Platysternonmegacephalum.

Buccal oscillation has been demon-strated in all major groups of vertebratesexcept mammals (Brainerd, 1999). Usingblowhole pneumotachography and video,we examined above-water buccal oscilla-tions in an aquatic turtle, Platysternonmegacephalum. In this study, we were ableto distinguish between oscillation and venti-lation based on tidal volume and sequenceof exhalation and inhalation phases. Themean tidal volume for oscillations was foundto be about 1/5 the tidal volume of lung ven-tilation. For ventilation, we recorded expira-tory tidal volumes of 6.251 ±0.85ml air, 5.645±0.802 ml air, and 6.523 ±0.829ml air forthree individuals respectively. The oscilla-tory tidal volumes recorded were 1.315±0.4931ml air, 1.208 ±0.439 ml air, and 0.953±0.569ml air. Oscillations also occur as in-spiration/expiration sequences in contrastto the expiration/inspiration sequence ofventilation. Through simultaneous measure-ment of hyoid depression and airflow, wesee a temporal correlation between hyoidmovement and airflow during buccal oscil-lations and also a small hyoid depression atthe start of respiratory exhalation. In exam-ining the relationship between oscillatoryand ventilatory events, preliminary data sug-gest that the two behaviors are independentwith no fixed phase relationship. We havefound that ventilation often interrupts the ex-piratory phase of oscillation thus overlap-ping the two behaviors. The data show amplevariation in the pattern and individual vol-umes of oscillations with periods of largecontinuous oscillation interspersed with fewbreaths and periods of smaller oscillationmore equally dispersed among breaths.Periods of ventilation only were recorded aswell. The variation suggests the possibilityof multiple functions of buccal oscillation.

27.2 DUDEK, D.M.*, FULL, R.J., Universityof California, Berkeley. Spring-like behaviorof the legs of running insects.

The dynamics of many terrestrial organ-isms during running are similar to those of abouncing spring-mass system. This obser-

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vation has led to the search for spring-likebehavior in the tendons of mammals. Thedynamics of running cockroaches havebeen modeled as a spring-mass system, butthe location of spring-like elements, if theyexist, remains a mystery. Cockroaches havesprawled postures with joint axes orientedvertically resulting in the possibility of a pas-sive, exoskeletal leg spring. Therefore, wedetermined the mechanical impedance (thetime-dependant resistance of a material todeformation) and resilience of the metatho-racic limb of a cockroach (Blaberusdiscoidalis) using dynamic oscillations. Thehind limb was removed and secured in anorientation consistent with that of a runninganimal. The leg was oscillated in the dorso-ventral direction (orthogonal to the plane ofrotation for the joints) and induced forcesrecorded. The resulting force-displacementrelationships were non-linear and similar inmany respects to the stress-strain curve forspider legs (Blickhan, 1986). As much as50% of the energy used to displace the legwas stored as elastic strain energy and re-turned. While the relative importance of vis-cous damping decreased with increasing os-cillation frequency, the impedance of the legincreased up to a frequency of 12 Hz. At fre-quencies above 12 Hz, the impedance ofthe leg remained constant. Interestingly, thestride frequency of running cockroaches in-creases with speed up to its preferred stridefrequency, which is between 10-14 Hz. Atfaster speeds, stride frequency remains con-stant. Taken together, these results suggestthat the effects of passive structures are sig-nificant and could allow the leg to act as adamped spring during locomotion. Sup-ported by ONR N00014-98-1-0669.

S11.6DUDLEY, R., University of Texas atAustin. Mechanisms and implications of ani-mal flight maneuverability.

The axial and torsional agility of flyinganimals derives from interactions betweenaerodynamic force production and the iner-tial resistance of the body to translation androtation, respectively. Anatomical and allo-metric features of body design thus mediatethe rapidity of aerial maneuvers. Both trans-lational and rotational responsiveness to ac-

celerations decrease with increased totalmass. The relatively heavy wings of volantvertebrates render their wing and body mo-ments of inertia of comparable magnitude.By contrast, insect taxa with the exception ofthe Lepidoptera possess relatively lightwings and correspondingly enjoy a reduc-tion in relative inertial resistance to body ro-tation. In many flying vertebrates, use of thetail facilitates the generation of aerodynamictorques and substantially enhances axialagility. Contrasting with maneuvers, stabil-ity in flight requires force and moment bal-ances that are attained via bilateral symme-try in wingbeat kinematics. All volant ani-mals fly using bilaterally paired appendages,whereas energetic costs of morphologicaland kinematic asymmetries between con-tralateral wings may be substantial. Geo-metrical constraints on wingbeat kinematicsmay limit force production and thus flightagility in many behavioral circumstances.Unitary limits to animal flight performanceand maneuverability are unlikely, however,given varied and context-specific interac-tions among anatomical, biomechanical,and energetic features of design.

P3.74DURICA, D.S.*, ANILKUMAR, G., WU,X., HOPKINS, P.M., University of Oklahoma,Sree Narayana College, India, University ofOklahoma, University of Oklahoma A searchfor EcR and RXR A/B isoform gene expres-sion during crustacean limb regenerationand oogenesis.

We have previously reported the isola-tion of EcR and RXR gene homologs in thefiddler crab, Uca pugilator. In insects,isoforms for both the EcR and RXR/USP pro-teins have been identified; these isoformsarise from the splicing of alternative A/B do-mains onto common C and E/F domains.Expression studies and mutant analysisstrongly suggest that these isoforms havedifferent physiological roles. Detailed analy-ses of the recovered crustacean clones,however, recovered an invariant A/B domainopen-reading frame for each gene. Ribonu-clease protection assays (RPA) were em-ployed to obtain an appraisal of the relativeratio of the recovered A/B domain-contain-ing transcripts to common domain UpEcR

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and UpRXR sequences. RPAs were con-ducted using limb buds corresponding tolimb regeneration stages used in previousstudies and were also initiated with ovariescontaining oocytes at different periods of oo-genesis. To compare the relative steady-stateabundance of A/B domain sequences tocommon domain sequence, RNAs were hy-bridized to both A/B domain and commondomain probes, and the level of protectiontritrated against known amounts of full-lengthsense cRNAs. At several stages examined,the relative level of A/B domain sequenceprotected is significantly less than commondomain; additional bands of lower molecu-lar weight resulting from hybridization to theA/B domain probe are also observed. Simi-lar results were obtained using ovarian tis-sue samples. The difference in the abun-dance of A/B containing transcripts relativeto total UpEcR and UpRXR mRNA suggeststhat alternative processing may produce A/B receptor isoforms in Uca, similar to thesituation observed in insects. The ovary alsorepresents another potential target tissue forecdysteroid control.

41.3 DURIE, C.J.*, TURINGAN, R.G.,Florida Institute of Technology, Melbourne.Relationship between durophagy and feed-ing functional design in marine fishes: in-traspecific variation in ecological morphol-ogy.

The relationship between oral jaw bio-mechanics and consumption of hard preywas compared between populations of twoperciform and five tetraodontiform speciesto examine intraspecific ecomorphologicalvariation in marine fishes. Gut content analy-sis revealed that the magnitude of durophagy(feeding on hard-shelled invertebrates, suchas crabs and sea urchins) varied betweenpopulations of each species. Difference inthe relative magnitude of durophagy be-tween populations was associated with in-traspecific differences in key biomechanicalproperties of the prey-capture and process-ing mechanisms. The more durophagouspopulations had more massive jaw bonesand muscles than conspecifics that con-sumed soft prey. We hypothesize that ma-rine fishes have the ability to alter the devel-

opment of their feeding mechanism to matchthe requirements for capturing and process-ing locally availabe prey-resources at post-recruitment habitats, such as coral reefs andestuaries.

65.5 DWORKIN, I.M.*, LARSEN, E.W,Univeristy of Toronto. Temporal dynamics ofthe interaction between homothorax andAntennapedia in D. melanogaster.

The antenna to leg transformations in-duced by dominant alleles of Antennapedia(Antp) have become classic examples ofhomeotic transformation in D. melanogaster.It has recently been suggested that this trans-formation is due to Antp mediated repres-sion of the homothorax (hth) gene. Loss ofhth activity from the antennal imaginal discresults in transformation to leg identity, andresults of co-expression of Antp and hth havebeen interpreted as rescuing the antennalphenotype. While Antp activity in the anten-nal disc does seem to repress hth transcrip-tion, several inconsistencies have lead usto investigate the interactions between thesetwo genes in a more quantitative manner.We have investigated how short pulses ofAntp via a heat shock mediated transgene(HS-Antp) induces morphological transfor-mations, and represses hth expression. Aswell, we have employed a HS-hth transgeneto examine the temporal dynamics of res-cue of the Antp mediated transformation. Ourresults indicate that there is only a weak cor-relation between loss of hth expression andmorphological transformation. Short pulsesof hth appear to be sufficient to induce par-tial rescue of the Antp mediated transforma-tion. These results will be discussed in termsof the presumed roles of hth in the antennaldisc.

P3.70DZIALOWSKI, E.*, VONPLETTENBERG, D., ELMONOUFY, N.,BURGGREN, W., University of North Texas,Denton, Freie Universitat, Berlin. Chronichypoxic effects on metabolism and hema-tology in developing chicken embryos.

Chicken embryos wereexposed tochronic hypoxia (PO2 ~ 131 mmHg) duringdevelopment, and assessed for detrimentalmetabolic effects and the ability to repair

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them. Eggs were incubated in one of fourgroups: untreated (i.e. 155 mmHg), or treatedwith continuous 15% hypoxia during days1-6 (D1-6), 6-12 (D6-12), or 12-18 (D12-18)with normoxia during the remaining incuba-tion. Metabolism (VO2), body mass, hemo-globin (Hb), and hematocrit (Hct) were mea-sured in eggs on days 12 and 18 and inhatchlings. Ability to maintain VO2 was mea-sured acutely during a step-wise decreasein PO2 from normoxia to hypoxia (55 mmHg).At day 12, VO2 from D1-6 and D6-12 popu-lations was significantly lower than untreatedeggs. Pcrit in D6-12 eggs was lower than inuntreated and D1-6 eggs. Body mass of day12 embryos in hypoxia from D6-12 was sig-nificantly lower than in untreated embryos,while Hct and Hb were higher. On day 18,D6-12 eggs had VO2 significantly lower thanuntreated eggs. Body masses of D6-12 andD12-18 eggs were significantly smaller thanuntreated eggs. Hct and Hb did not differbetween treatments. In hatchlings, VO2,mass, Hb, and Hct were similar among treat-ments. However, D1-6 and D12-18 eggsproduced hatchlings with lower Pcrits thanuntreated eggs or D6-12 hypoxia exposedeggs. Long term effects of hypoxia on VO2

and mass occurred in D6-12 embryos. Dif-ferences in VO2 and mass between untreatedeggs and D6-12 eggs were observed onday 12 and 18, but disappeared upon hatch-ing. Chronic hypoxic exposure during criti-cal periods in development alters the devel-opmental physiological trajectories andmodifies the phenotypes of developing em-bryos.

P1.20EADS, B.D.*, HAND, S.C., Universityof Colorado, Boulder, Louisiana State Univ,Baton Rouge, Dept of Biologi. Modulatingmitochondrial transcription in Artemiafranciscana embryos.

Gastrula stage embryos of the brineshrimp Artemia franciscana exhibit devel-opmental and metabolic arrest in responseto adverse environmental conditions suchas anoxia. This arrest is coordinated andprofound, indicating a high degree of con-trol at the level of gene expression. Previ-ous studies have shown an arrest duringanoxia of protein synthesis and degrada-

tion, with concomitant extension of proteinhalf-life, as well as decreased nuclear tran-scription. Mitochondria isolated from theseembryos provide an ideal system in whichto study mechanisms of transcriptional modu-lation during physiological challenge, includ-ing lack of O2 and the lowered ATP concen-trations and pHi associated with anoxia. Forexample, mitochondrial half-life can be mea-sured in organello in a way impossible withisolated nuclei. Using dot blots of mtRNA,mitochondria exposed to anoxia in vitro hadsignificantly longer RNA half-lives than didaerobic mitochondria, indicating degrada-tion is arrested by lack of oxygen. In addi-tion, when exposed to anoxic pHi in vitro, aneven greater proportion of the mtRNA waspresent after 6 h than in anoxic samples,demonstrating that the pH decline duringanoxia is more important for halting degra-dation than is O2 lack per se. We tested thehypothesis that lack of ATP is a mechanismfor halting RNA degradation under anoxiaby adding 1 mM ATP in vitro to anoxic mito-chondria and found no increase, suggest-ing that lack of ATP is unlikely to be a causalmechanism. We also developed a nucleaseprotection assay for new transcription initia-tion events to test whether initiation by iso-lated mitochondria contributes to overall tran-script levels. Preliminary data indicate thatthis is the case, and that anoxia decreasesthe amount of de novo initiation.

48.1 EARLS, K.D., American Museum ofNatural History. Skeletal diversity and mor-phology in Anseriformes: an explicitly phy-logenetic analysis.

Birds are very conservative in their over-all morphology, and yet have diversifiedacross a remarkable spectrum of locomotorbehaviors. The associations of morphologywith locomotor specializations have beenmurky, however, due to a lack of resolutionwithin and among many avian clades. Whileit has been shown in other vertebrate groupsthat changes in bone shape and strengthare often associated with locomotor transi-tions, this has not been clearly demonstratedfor birds. To shed light on this problem, Ihave performed an explicitly phylogeneticanalysis of bone morphology in the

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Anseriformes (ducks, geese) with two pri-mary goals. First, I test the relationship be-tween bone morphology, locomotor special-ization, and phylogenetic history. Second, Ievaluate the effects of competing phyloge-netic hypotheses on the morphologicalanalysis. This study is a first step towardunderstanding morphological changeswhich may have occurred early in the radia-tion of modern avian taxa.

19.6 EDBLOM, T.L.*, KARASOV, W.H., Uni-versity of Wisconsin-Madison. Solar ultravio-let-B radiation does not affect hatching suc-cess of Rana pipiens (northern leopard frog)eggs under natural conditions along a con-tamination gradient.

We compared the hatching success ofRana pipiens (northern leopard frog) eggsat field sites located along a known contami-nation gradient in the Green Bay and FoxRiver ecosystem, Wisconsin, U.S.A. Our in-vestigation was designed to determinewhether there were differences in hatchingsuccess or incidence of deformities wheneggs were covered with shields that trans-mitted different levels of UV-B. We alsowanted to determine if UV-B might be actingsynergistically with agents in the water tofurther reduce hatching success and in-crease incidence of deformities at the morecontaminated field sites, as indexed by sedi-ment polychlorinatd biphenyl (PCB) andheavy metal levels. One Green Bay pondand one Green Bay wetland site were rela-tively uncontaminated (both <0.025 mg/kgsediment PCB concentration). AnotherGreen Bay wetland site and a Fox River sitewere relatively more contaminated (3.7 and3.2 mg/kg sed. PCB conc., respectively). Wefound significant differences in both hatch-ing success and incidence of deformitiesbetween sites in the field, but these differ-ences were not attributable to UV-B. Fur-thermore, there was no relationship betweenhatching success and level of contamina-tion. These results suggest that leopardfrogs, at least at the egg (for hatching suc-cess) and early tadpole (for deformities)stages may not be sensitive to current levelsof UV-B radiation even in somewhat pollutedenvironments.

P2.6 EDSINGER-GONZALES, E.*, VANDER ZEE, M., DICTUS, W.J.A.G., VAN DENBIGGELAAR, J.A.M., University of Utrecht.The development of radialized and twinnedgastropod embryos and its implication forspiralian development.

Establishment of the adult body plan inmolluscs requires induction by the blas-tomere 3D during embryogenesis. To under-stand 3D’s developmental function, we in-terfered with its specification in the gastro-pod, Tectura scutum, and examined subse-quent development. By incubating embryosin brefeldin-A, a fungal toxin that rapidly andreversibly dissolves the Golgi apparatus, wecan temporarily shut down cell-cell commu-nication. Varying either the concentration ofbrefeldin-A or the timing of treatment resultedin 100% radialized, twinned or normal lar-vae. In absence of 3D, radialized embryosdid not establish bilateral cleavage symme-try. Despite this, development closely fol-lowed that of control larvae as they under-went gastrulatation and differentiated adulttissues. As veligers, gastropod larvae arebilaterally symmetric with the dorsal-ventralaxis at a right angle to the animal-vegetalaxis. In contrast, radialized larvae maintainedthe quadri-radial symmetry of the embryo,with dorsal-ventral structures occuring in aradial series along the animal-vegetal axis.Twinned embryos shared an animal apicaltuft and a vegetal mouth while all other struc-tures developed in duplicate and as mirrorimages across the animal-vegetal axis. Wepropose that 3D’s developmental function islimited to the establishment of bilateral sym-metry. By breaking the continuity of quadri-radial symmetry against a backdrop of re-gional determinants along the animal-veg-etal axis, 3D’s signal enables previouslyequivalent blastomeres to establish identi-ties. The adult body plan then arises overthe course of gastrulation by a process ofprogressive induction, the product of de novointeractions resulting from stereotypic, celllineage-defined gastrulation movements.

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69.2 EDWARDS, R., DePaul UniversityCultural evolution of scientific values: grantoverhead in a parasite-host model.

From 1968 to 1992, basic science in theUnited States experienced an economiccondition so pervasive and significant that itwas rarely acknowledged to occur. Duringthis period, “grant overhead,” or the requestedpercent by which a grant budget was in-creased, was not limited to any specificamount, but rather was negotiated annuallywith no set limit. The requested amounts rap-idly increased from a maximum of 20% to insome cases over 80%. Neither the neces-sary paperwork (e.g. Circular A-21) nor theDepartment of Health and Human Serviceswere then equipped for this degree of nego-tiation, and by the early 1980s these monieshad become an important source of operat-ing funds for university administrations. Fac-ulty hiring and success reflected these pri-orities, and the ability to generate overheadfunds became a central factor of academiclife. Most significantly, the administrative pri-orities had become internalized by facultyas values. This presents a remarkable ex-ample of cultural evolution, using funds as amarker of energy: during this period, a para-site-host system operated up to and includ-ing the modification of the host’s behavior infavor of parasite vigor. I present both themechanics and the impact of this system onourselves as academics and scientists, in-cluding aspects of teaching, hypothesis test-ing, mentoring, and status. Also, Congres-sional hearings in 1992 have led to an im-portant change in the system, such that ad-ministrative overhead is limited to 26%. Thischange is beginning to affect academia andits grant-oriented practices. I present an out-line of the relevant concerns and issues.

P2.28EDWARDS, D.D., University of Evans-ville. Increased fluctuating asymmetry amongchironomid midges in response to ectopara-sitic water mites: implications for fluctuatingasymmetry theory.

The larvae of most species of water mitesmust undergo a brief parasitic phase withinsects to complete their life cycle. Severalstudies have found a significant correlationbetween mite load and the degree of fluctu-

ating asymmetry (FA) host characters, sug-gesting that mites increase FA through theireffect on developmental stability. To date, FAprimarily has been reported among hemi-metabolous insects that become infestedduring pupal ontogeny. Holometabolous in-sects that are parasitized by mites when theyare adults are not expected to exhibit FA be-cause they are infested once they have com-pleted development. Parasitic associationsbetween the water mite Unionicola foili andthe holometabolous midge Chironomustentans were established in the laboratoryand revealed that FA of forewing length wassignificantly greater in infected than inuninfected midges. These results are incon-sistent with the initial prediction, suggestingthere are other mechanisms by which larvalmites may affect FA of host midges. Behav-ioral observations revealed that the pres-ence of mite larvae induced an increase inantiparasitic behavior by pupal C. tentans.Because antiparasitic behavior id assumedto be extremely time consuming and ener-getically expensive, it may be expected tohave an affect on the developmental stabil-ity of midges and thus increase the degreeof FA.

18.3 EDWARDS, D.R.*, WOODIN, S.A.,University of South Carolina, Columbia.Should worms of a feather stink together?The effects of prey density and aggregationon predator deterrence.

Halogenated hydrocarbons are wide-spread among hemichordates and polycha-etes in temperate sedimentary environments.The bromophenols produced by somelarger (>3cm in length) macroinfauna act aspredator deterrents. However, many of theinfaunal organohaline producers are small(<1cm in length), especially in relation to thebite size of their common predators. Theability of these small organisms to deterpredators may be dependent not only onthe production of deterrent compounds byindividuals, but on the structure of the sur-rounding community. In this study, we ex-amine whether patches of small individualswith such compounds are less palatable toinfaunal predators than patches of individu-als without, and whether deterrence is de-

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pendent on prey density. Spot (Leiostomusxanthurus), mummichogs (Fundulusheteroclitus) and grass shrimp(Paleomonetes sp.) were offered patches ofsmall (1-2 mm3) cubes of surimi with andwithout bromophenols. The cubes were of-fered at a high density (100 cubes/0.01 m2),low density (30 cubes/0.01 m2), and an ag-gregated low density (30 cubes divided into6 1cm2 patches). Results of these choiceexperiments demonstrate that, at least forsome predators, bromophenols are effec-tive predator deterrents for small prey, andthat this effect increases with density andaggregation.

S5.1 EHLERINGER, J.*, CERLING, T., Uni-versity of Utah. Possible relationships be-tween atmospheric carbon dioxide andmammalian grazers.

We explore the possible relationshipsbetween photosynthetic pathway, changingatmospheric carbon dioxide, and mamma-lian herbivores. Atmospheric carbon diox-ide levels have changed over the last 200million years; the recent pattern of increas-ing anthropogenic emissions has resultedin a dramatic increase in atmospheric car-bon dioxide today that differs from atmo-spheric carbon dioxide in the glacial-inter-glacial cycles of the past. At the same time,many questions remain unanswered aboutabrupt changes in mammalian diversity.Might the observed changes in atmosphericcarbon dioxide and changes in mammaliandiversity be related through photosyntheticpathway differences that occur as a functionof environmental conditions? Modeling ef-forts predict shifts in C3/C4 plant abundancein response to changes in atmospheric car-bon dioxide. Our objectives are to better un-derstand the constraints that atmosphericcarbon dioxide places on ecosystem pro-ductivity, which may in turn influence mam-malian grazers.

26.4 EIDIETIS, L.*, WEBB, P.W.,FORRESTER, T.L., University of Michigan,Ann Arbor. The abilities of two morphologi-cally different fishes to counteract rollingdisturbances.

We increased rolling moments and de-creased negative metacentric heights of

spiny rayed Lepomis macrochirus (bluegill)and soft rayed Semotilus atromaculotus(creek chub) by attaching weights and floatswhich, together, were neutrally buoyant.Weight and buoyant force were normalizedby fish mass, and moment arms and meta-centric heights by volume-1/3. Fish behav-ioral responses used to counteract the dis-turbance were observed in conditions thatrestricted swimming and in conditions thatallowed free swimming. Threshold re-sponses were defined when a disturbancefirst caused fish to roll 90ƒ (the limit of initialstability) and when fish were not able to rightthemselves (the limit of ultimate stability).When swimming was restricted, initial sta-bility was greater for chub than bluegill.When conditions allowed free swimming,initial stability was similar for both species.Ultimate stability was similar for both spe-cies irrespective of whether swimming wasrestricted.

P3.55ELF, P.K.*, FIVIZZANI, A.J., Universityof North Dakota. Changes in sex steroid lev-els in the yolks of the Leghorn chicken,(Gallus domesticus), during embryonic de-velopment.

We have hypothesized that yolk hor-mones play a role in sexual differentiation inspecies with temperature-dependent sexdetermination (TSD), in which incubationtemperature determines the sex of the off-spring. To compare possible differences inyolk hormone patterns between TSD ani-mals and those with genetic sex determina-tion (GSD), a series of experiments havebeen initiated using the Leghorn chicken,Gallus domesticus. The chicken was cho-sen for this study because its sexual differ-entiation has been well characterized. Thepurpose of these investigations was to de-termine changes in the levels of androstene-dione (A), dihydrotestosterone (DHT), estra-diol (E) and testosterone (T) in the yolks ofchicken eggs during embryonic develop-ment. Eggs were collected, labeled for clutchand egg number, and incubated at 37.8oC.Eggs were sacrificed at predetermined timesduring development, embryos staged andyolk material collected. Yolks werehomogenizedand hormones extracted. A,

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DHT, E and T were separated via columnchromatography and hormones measuredusing RIAs. Results show decreases in thelevels of both A and T during embryogen-esis, similar to those we reported in the alli-gator, with A levels being significantly greaterinitially than those of all other hormones.DHT levels mirrored those of T. Chicken Elevels however, differed from those we mea-sured in both the turtle and the alligator. Elevels were less than T throughout most ofdevelopment, and though they do declineslightly, E levels in yolks of chicken eggsshow a significant increase between embry-onic stages 40 and 45.

P2.65ELLERBY, D.J.*, SPIERTS, I.L.Y.,ALTRINGHAM, J.D., University of Leeds,Niels Stensen Foundation. Fast muscle func-tion in the European eel (Anguilla anguilla,L.) during aquatic and terrestrial locomotion.

Eels are capable both of locomotion inwater and on land using undulations of thebody axis, powered by the lateral muscula-ture. Differences in kinematics and the un-derlying patterns of fast muscle activationare apparent between locomotion in thesetwo environments. Fast muscle power out-puts were measured using the work looptechnique, under conditions that simulatedtheir use during aquatic and terrestrial loco-motion. The muscle strain and stimulationparameters associated with swimming gen-erated greater force and power than thoseassociated with terrestrial crawling. This de-crease in muscle performance may occurbecause on land the eel is constrained to aparticular kinematic pattern in order to pro-duce thrust against an underlying substrate.Muscle properties changed along the bodyaxis as reported in other teleost fish. Maxi-mum power outputs using optimal strain andstimulation parameters were 17.3 ± 1.3 Wkg-

1 in muscle from 0.45 BL (body lengths fromthe snout) and 16.3 ± 1.5 Wkg-1 in musclefrom 0.75 BL. Time from stimulus to peakforce Ta was 82 ± 6 ms at 0.45 BL and 93 ± 3ms at 0.75 BL. Time from stimulus to 90 %relaxation T90 was 190 ± 13 ms at 0.45 BLand 228 ± 11 ms at 0.75 BL.

26.3 ELLERBY, D.J.*, SPIERTS, I.S.Y.,ALTRINGHAM, J.D., University of Leeds,Niels Stensen Foundation. Slow musclepower output of yellow- and silver-phaseEuropean eels (Anguilla anguilla, L.):changes in muscle performance prior to mi-gration.

The European eel (Anguilla anguilla, L.)has a complex life cycle involving a lengthyspawning migration. The differences in thelocomotory demands on different life historystages are considerable. Eels swim in theanguilliform mode in which muscle functionhas been assumed to be relatively uniformalong the body axis relative to other teleosts.The work loop technique was used to deter-mine slow muscle power outputs in yellow(non-migratory) and silver (migratory) lifehistory phases. Swimming kinematics of thetwo phases were also measured for com-parison. Maximum slow muscle power out-puts under approximated in vivo conditionswere 0.24 Wkg-1 in yellow-phase eel and0.74 Wkg-1 in silver-phase eel. Power outputpeaked at cycle frequencies of 0.23 to 0.8Hz. Muscle activation (Ta) and relaxation (T90)times were greater in yellow- than in silver-phase eels. Differences in swimming kine-matics and the frequency distribution oftailbeat frequency at a swimming speed of0.40 BLs-1 suggested differences in under-lying patterns of muscle recruitment betweenthe two life history phases.

P2.42ERNST, H.H.*, RICHARDSON, J.F.,SATTERLIE, R.A., Arizona State University.Morphological changes in an asymmetricneuron of the right pleural ganglion in thesexually mature vs. immature pteropod mol-lusk.

One of the largest neuron somata of theright pleural ganglion of Clione limacinabelongs to a cell that does not have a homo-logue in the left pleural ganglion. In the im-mature animal, the soma is around 50um indiameter and appears translucent with sub-stage illumination. In the mature animal, thesoma is around 80um in diameter and ap-pears opaque. With illumination from above,the cell is white in color. Light and electronmicroscopical examination of both immatureand mature “Pleural White Cells” indicate

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the presence of numerous, large dense-cored vesicles in the cytoplasm of the ma-ture animals, but not in the immatures. Inaddition, several smaller pleural neurons ap-pear light opaque in mature animals. Theappearance of the white color in the smallerneurons, but not in the Pleural White Cell, iscoincident with immunoreactivity of smallneurons to an antibody to Aplysia egg-lay-ing hormone. Similarly, immunoreactivesomata, to an Aplysia sensorin antibody,which is believed to specifically label pri-mary mechanosensory neurons, is found inthe right, but not the left pleural ganglion ofsexually mature animals. Again, only smallneurons are labelled. Thus significant mor-phological changes, and presumed physi-ological changes, occur in the right plerualganglion of Clione when it develops sexualmaturity.

S10.4ESCH, G., BARGER, M., FELLIS, J.,Wake Forest University. Transmission of para-sitic helminths: style, elegance, complexity.

Traditionally, the field of parasitology hasdealt with eukaryotic animals, to the exclu-sion of viruses, bacteria, fungi, etc., which isthe way we will approach our presentation.Our focus will be on certain ecological as-pects of the life cycles and life-history strate-gies employed by digenetic trematodes, adiverse group of platyhelminths that includessome 25,000 described species. More spe-cifically, our interests rest with the nature ofhost/parasite interactions within molluscanintermediate hosts and the manner in whichthese interactions, or lack thereof, functionin structuring trematode infracommunitieswithin these molluscan intermediate hosts.Literature in this area suggests that preda-tion/competition may be a significant struc-turing force for infracommunities in certainmarine prosobranchs, but not others, andthat temporal/spatial factors may be involvedas structuring forces in at least some fresh-water pulmonates. These, and other, issueswill be discussed.

67.3 ESPINOZA, N.R., Louisiana StateUniversity, Baton Rouge. Effects of develop-mental temperature on musculoskeletalgrowth and jumping performance in thetreefrog Hyla chrysoscelis.

Several vertebrate species have shownontogenetic adjustments in the form andmaterial properties of the growing muscu-loskeletal system to allow the same level oflocomotor performance in juveniles andadults. The rate of growth and amount oftime the musculoskeletal system has to de-velop may affect the amount of compensa-tory change needed to produce the samelevel of performance; for example, the fasterthe growth rate and/or the shorter the amountof time for development, the greater the needfor these adjustments. To test these predic-tions, individuals of Hyla chrysoscelis wereraised at 28ƒC and 18ƒC to evaluate theeffects of developmental duration and growthrate on bone and muscle morphology, bonematerial properties, and jumping perfor-mance. Although two-fold differences in de-velopmental duration and larval growth rateswere found between frogs raised at 28ƒCand 18ƒC, little or no difference was foundin hind limb morphology, bone shape, bonemineral content, bone material properties,relative muscle mass or jumping perfor-mance at the end of metamorphosis. How-ever, during the first nine weeks of post-meta-morphic growth in both groups, absolutejumping performance, relative proportion ofhind limb muscle mass, and bone materialproperties changed with age. These resultssuggest that an increase in the relative pro-portion of hind limb muscle mass, as well asan increase in the strength and stiffness ofthe hind limb skeleton, contribute to the im-provement of jumping performance duringpost-metamorphic growth. Supported by aHoward Hughes Predoctoral Fellowshipand NSF (IBN-9701121).

P2.77ESSNER, R.L., Ohio University, Ath-ens. Comparison of takeoff kinematics in glid-ing and nongliding squirrels.

Precise descriptions of behavior are keyto understanding the role of morphology inthe evolution of novel locomotor modes.While a number of studies have comparedmorphological variation among gliding andnongliding forms, there is currently a lack ofinsight into the extent of variation among lo-comotor behaviors. This has led to ques-tions concerning the degree of specializa-

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tion necessary for gliding versus nongliding(leaping) locomotion. In order to addressthis concern I examined takeoff kinematicsin a gliding arboreal sciurid (Glaucomysvolans) and two nongliding relatives(Tamiasciurus hudsonicus, Tamias striatus).Animals were filmed launching from a 1.5-meter horizontal platform with high-speedvideo at 240 frames/second in lateral anddorsal views. Landmarks were digitized onthe limbs, tail, and body and converted into3D coordinates. Locomotor behavior wasexamined by generating kinematic profilesof angular motion at the limb joints and tail.Comparisons among the three taxa revealedsimilarities in the majority of kinematic pa-rameters, indicating that takeoff behavior inthese arboreal rodents is relatively conser-vative. Furthermore, the presumed evolu-tionary transition from leaping to gliding likelydid not involve substantial changes relatedto the takeoff phase of locomotion.

P1.26ESTES, A.M.*, KEMPF, S.C., HENRY,R.P., Auburn University. Carbonic anhydraseinduction by zooxanthellae in Cassiopeaxamachana.

Endosymbiotic dinoflagellates ofcnidarians are encased in multiple mem-branes, causing difficulty in acquiring inor-ganic carbon for photosynthesis. Host car-bonic anhydrase(CA), which catalyses thereversible dehydration of HCO3-, can sup-ply endosymbionts with unlimited CO2 byaccessing the large HCO3- pool in seawater.Bell tissue from Cassiopea xamachana, wasexamined to determine if the localization andinduction of CA activity were correlated withthe density and location of zooxanthellae.Symbiotic and regenerated recolonizedC.xamachana bell tissue had 5 times and1.7 times, respectively, greater CA activitythan aposymbiotic native and regeneratedtissue. Symbiotic native and recolonized tis-sue contained respectively, 3 and 6 foldgreater algal populations than aposymbiotictissues. The oral epithelial layer, which re-ceives more intense sunlight, had 1.2 greaterCA activity and 5 times the algae than abo-ral. CA localized using the fluorescent in-hibitor 5-dimethylaminonapthalene-1-sul-fonamide (DNSA), revealed symbiotic and

oral epithelial tissues 1.5 times brighter thanaposymbiotic and aboral tissues. CA activityand algal density in symbiotic andaposymbiotic animals were highest at thebell edge and lowest near the manubrium.Thus, the postion and density of algal popu-lations are positively correlated with CA con-centration and location. Symbiotic C.xamachana incubated in the Photosystem Iinhibitor, 3-(3,4 dichlorophenyl)-1,1-dimethylurea (DCMU)showed a 1.7 fold de-crease in CA activity after five days. Thus,not only algal density, but also photosyn-thetic rate determines CA concentration.

S10.10 FAETH, S.H., Arizona State Univer-sity, Tempe. Fungal endophytes and hostplant symbioses: mutualism, neutralism, orantagonism?

Systemic endophytic fungi are thought tointeract mutualistically with their host grassesmainly by increasing resistance to herbi-vores via alkaloids, as well as by increasingdrought resistance, germination success,competitive abilities and deterring seedpathogens and predators. However, anti-herbivore effects have been documentedonly for a relatively few grasses, mostly ag-ronomic ones, and mostly on non-nativeherbivores. There are few studies of the in-teraction of endophytes in native grass popu-lations and communities. I show that rela-tively few native grasses infected with sys-temic endophytes have strong negative ef-fects on either invertebrate or vertebrate her-bivores. Observational and experimentalstudies of Neotyphodium-infected Arizonafescue, a widespread and native grass, dem-onstrate a general lack of herbivore resis-tance. In field and greenhouse experiments,infected seeds show reduced germinationsuccess and increased susceptibility to fun-gal pathogens. The only positive effects ofthe endophyte appear to involve increasedrates of plant growth, but only under specificenvironmental conditions and only with cer-tain plant genotypes. I propose that the mu-tualism between endophytes and hostgrasses is conditional based upon plant andfungal genotype, which influence alkaloidproduction, and environmental factors.

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S6.4 FARMER, C.G., University of Utah, SaltLake City. Myocardial oxygenation and theevolution of the vertebrate cardiopulmonarysystem.

For many vertebrates, there are no othernormal stresses to which the cardiopulmo-nary system is exposed that come close tothe extreme stresses of heavy exercise.Hence it is expected that the demands ofexercise have exerted strong selection pres-sures on the evolution of vertebrate cardiop-ulmonary system. I have been examiningthe importance of air-breathing during exer-cise in several fishes as a potential mecha-nism of myocardial oxygenation. Similarly, Ihave been investigating the importance ofthe intracardiac shunt of reptiles in myocar-dial oxygenation during exercise. This re-search has employed a variety of techniques(ECG, blood gas, blood pressure, and bloodflow measurements). Although preliminary,my findings suggest that myocardial oxygen-ation is not adequate in some air-breathingfishes when exercising in well oxygenatedwater but denied access to air. Furthermore,when the potential benefits to myocardialoxygenation of the intracardiac shunt are re-moved by exercising turtles under hypoxicconditions, cardiac function is perturbed.Hence, the necessity of an adequate supplyof oxygen to the heart during activity mayhave influenced the evolution of the verte-brate lung and the intracardiac shunt.

P3.72FASANO, C.*, QUACKEN-BUSH, L.S.,University North Carolina, Wilmington.Growth of juvenile blue crabs,Callinectessapidus.

In North Carolina’s Cape Fear River es-tuary, juvenile blue crabs are often found insand and mud habitats far beyond the mouthof the estuary. Predators, prey availability orother factors, may drive the crabs’ invasionof the low salinity portions of the estuary. Wealso expected that there would be conse-quences on the growth rates of these juve-nile blue crabs. We collected small (8-22mm) juvenile crabs at the mouth of the estu-ary and monitored their growth over severalmolt cycles in a controlled lab environment.The smallest blue crabs had the largestgrowth rates, these rates slowed as the crabs

increased in size. Crabs growing at threedifferent salinities had about equal growthrates, and equal molt cycle durations, butsignificant differences in the number of moltscompleted. It appears that low salinity areasare suitable for rapid crab growth, whenother factors are controlled. Supported bythe CRUI program grant : DBI: 99-78613 fromthe National Science Foundation.

7.5 FAUCHALD, K., Smithsonian Institu-tion. Distribution of scales in polynoid scale-worms (Annelida, Polychaeta).

Polynoids have some of the dorsal cirrireplaced by flattened scales (elytrae) moreor less covering the body. An overview ofthe type species of most genera of the familydemonstrated a few interesting patterns.Species with less than 12 pairs of elytrae allhave less than 30 segments and are foundin deep water, either pelagically or associ-ated with hot vents. These taxa appear tobelong to several different clades. The first12 pair of elytrae are always on segments 2,4, 5, 7, 9, 11, 13, 15, 17, 19, 21 and 23. Thenext three pairs of elytrae are usually eitheron segments 25, 27 and 29 or on segments26, 29 and 32; the latter is by far the mostfrequent and a very large number of polynoidtaxa have 15 pairs of elytrae with this distri-bution. Most taxa with 15 pairs of elytrae con-sist of less than 40-45 segments; but a fewlong-bodied taxa with as many as 100 seg-ments lack elytrae on the posterior half ofthe body. When more than 15 pairs of elytraeare present, the distribution on segments 30-45 is often irregular and variable, except intaxa with 18 pairs of elytrae in which pat-terns corresponding either to the 25, 27, 29or the 26, 29, 32 patterns are present. Inlong-bodied taxa with 50 or more segments,the distribution stabilizes in most taxa intotwo patterns with the elytrae present on ei-ther every second or every third segment,corresponding to the patterns seen on seg-ments 24-32. In many species the two lastpairs of elytrae are on consecutive segmentsno matter what the previous distributionwere. The distribution of the elytrae corre-lates better with the numbers of segmentspresent than with the length of the speci-mens. Short-bodied taxa appear to have

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evolved at least twice within the family, as-suming that the long-bodied condition isplesiomorphic.

S15.10 FEDAK, M.*, LOVELL, P.,MCCONNELL, B., HUNTER, C., Universityof St Andrews. Methods for overcoming theconstraints of long range telemetry of bio-logical information from animals: gettingmore useful data from small packages.

Many species carry out their most inter-esting activities where they can not be ob-served or monitored. Marine mammals areperhaps extreme in this group, accomplish-ing their most astounding activities both dis-tant from land and deep in the sea. Collec-tion, storage and transmission of data aboutthese activities are constrained by the en-ergy requirements and size of the recordingloggers and transmitters. The more bits ofinformation collected, stored and transmit-ted, the more battery is required and the largerthe tag must be. We therefore need to beselective about the information we collect,while maintaining detail and fidelity. To ac-complish this in the study of marine mam-mals, we have designed “intelligent” datalogger/transmitters that provide context-driven data compression, data relay, and au-tomated data base storage. We later com-bine these data with remotely sensed envi-ronmental information and other oceano-graphic data sets to recreate the environ-mental context for the animal’s activity, andwe display the combined data using com-puter animation techniques. In this way, thesystem can provide near real time “observa-tion” of animal behaviour and physiologyfrom the remotest parts on the globe. To il-lustrate the approach, we will present ex-amples of its use in southern elephant sealsand beluga whales from the polar seas.

S5 FEDER, M.E., University of Chicago.Plant and animal comparative physiology/biochemistry, evolutionary physiology, eco-logical physiology, and physiological ecol-ogy: opportunities for synergy.

Both the communities of plant biologyresearchers and animal biology research-ers include multidisciplinary groups thatcombine physiology, ecology, biochemistry,biomechanics, and evolution, but historically

these groups have often been as distinct asthe organisms they study. This symposiumwill challenge this historic distinction by ask-ing in what ways the study of plant and ani-mal function in environmental/evolutionarycontext need be separate disciplines, whatbiological issues transcend the two commu-nities, and how best can plant and animalbiologists realize the synergies afforded bytheir complementary viewpoints and studyorganisms? To do this, the symposium willpartner distinguished plant and animal bi-ologists to discuss topics of mutual interest:global climate change; sensing, signalling,and responding to the environment; mecha-nisms and implications of dormancy; andbehavior versus tolerance as alternative re-sponses to environmental stress.

S13.7FENCL, H.S., University of WisconsinSystem. Reaching all students: supportingdiversity in a science classroom.

This session will explore both the impor-tance of, and resources for, teaching a di-verse group of students. Athough the em-phasis of the discussion will be on gender-conscious teaching, many of the issuesraised are equally important to minority stu-dents and those from a spectrum of socio-economic backgrounds. Ideas and re-sources for curricular reform—of a singlecourse or across the major—will be pre-sented. Experiences of educators at the UWSWomen & Science Curriculum Reform Insti-tute will be used as illustrations.

P3.93FENTRESS, J.A.*, BROUWER, T.H.,BROUWER, M., MCLACHLAN, J.A.,CHEEK, A.O., Southeastern Louisiana Uni-versity, Hammond, University of SouthernMississippi, Ocean Springs, University ofSouthern Mississippi, Ocean Springs,Tulane University, New Orleans, LA, South-eastern Louisiana University, Hammond. Ex-amination of a potential environmental anti-estrogen.

Anthracene, a polyaromatic hydrocarbon,has been shown to induce anti-estrogeniceffects in fish. In the medaka, Oryzias latipes,short term exposure to 12 or 20ug/ml an-thracene (ANT) blocks estrogen inducedfeminization, while long term exposure leadsto reduced fertility and hatching success. To

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determine if anthracene is an estrogen re-ceptor antagonist, we measured vitellogenin(VTG) production in response to estradiol(E2) +/- anthracene. VTG serves as a natu-ral reporter gene for estrogen receptor acti-vation. We exposed fry for 2 or 8 weeks posthatch to one of the following treatments:water, solvent, 1 nM E2, 12 ug/ml ANT, 20ug/ml ANT, 1nM E2 + 12 ug/ml ANT, or 1nME2 + 20 ug/ml ANT. Fish were sub-sampledat 2, 4, and 8 weeks post hatch for VTG analy-sis. Vitellogenin was analyzed using West-ern blots and quantified by densitometry. Fryexposed to estrogen for 2 weeks andsampled at 2 weeks produced VTG, whilefish sampled at 4 and 8 weeks showed anattenuated response to estrogen. Fish ex-posed to estrogen for 8 weeks producedVTG throughout the exposure period. Whenexposed to ANT alone fish did not produceVTG. Regardless of dose or exposure dura-tion, ANT did not prevent the production ofvitellogenin in co-exposed fish. Becauseanthracene was unable to block the produc-tion of vitellogenin, it is unlikely that its anti-estrogenic effects are mediated through theE2 receptor.

S6.10FERRY-GRAHAM, L.A.*, WAIN-WRIGHT, P.C., University of California Davis,University of California Davis of CaliforniaDavis. Using functional morphology to testgeneral ecological theory.

Even before Hutchinson defined what hecoined the ëfundamental nicheí, research-ers have been striving to understand what itis that makes species different, and what al-lows them to survive in the time and spacethat they do. Since that time, many theorieshave been advanced which encompass anarray of ecological, evolutionary, mathemati-cal, and simply logical principles. The goalhas been to develop ecological theories thatcan, among other things, make specific androbust predictions about how and where or-ganisms should live. An often underesti-mated or unexplored parameter of thesemodels is the role of the organismsí func-tional morphology. A more complete under-standing of how the features of an organismísanatomy work to allow the organism to ac-complish certain tasks has allowed us to re-

visit some of these models from an enlight-ened perspective. We use kinematic stud-ies of prey capture in several types of fishesas model systems to generate and test pre-dictions related to diet specialization andbreadth. These include, but are not neces-sarily limited to, predictions regarding whyan organism might specialize, and the po-tential ecological and evolutionary conse-quences of specialization. We also considerseveral definitions of specialization and at-tempt to align these based upon shared eco-logical and evolutionary principles. We notethat not all functional morphological systemsare ideal for testing ecological models, asmany ecological models depend on otherlevels of organismal design for predictingcommunity patterns (i.e., behavior or sen-sory biology). We attempt to identify anddefine the characteristics of those certainfunctional morphological systems that makethem useful for testing general ecologicalmodels and lead to robust predictions.

S3.11FETCHO, J.R., SUNY at Stony Brook.New approaches to the function of neuronalcircuits that might simplify (a little) studies ofthe evolution of behavior.

Understanding motor patterns (elec-tromyograms) and their evolution requiresunderstanding the neuronal circuits that pro-duce them and the evolutionary changes inthose circuits. This is not easy, which is per-haps why there are not many explicitly com-parative studies of the functional organiza-tion of motor circuits for feeding or other ver-tebrate behaviors. Simply identifying whichneurons are involved in a particular behav-ior in even one species is a challenge anddoing this in a comparative way has beenunrealistic. The problem is even more com-plicated because over the last decade neu-robiological studies have shown how plas-tic the nervous system really is. Changes inmotor output, even within a single animal,can occur in many ways, including changesin synaptic connections, alterations in ionchannel expression in neurons, or a restruc-turing of the function of neuronal circuits byneuromodulators. The challenge is to de-velop techniques that are easily applicableacross species which allow one to identify

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the active neurons in a behavior and to testtheir function. Such approaches would thenallow for comparative studies of motor cir-cuits in animals with differing motor patterns.We have been applying optical methods andfluorescent indicators to image which neu-rons are active during behavior of larval fishand to reconstruct their morphology in thelive animal. In addition, we have developedapproaches to laser kill neurons to test theirfunction in vivo. These approaches, com-bined with powerful new genetic tools forfluorescently labeling neurons, should al-low a more ready attack on the problems ofexactly what the motor circuitry is for behav-iors such as feeding and how it has changedin conjunction with the evolution of newmotor patterns.

49.4 FILORAMO, N.I.*, SCHWENK, K.,University of Connecticut. Ultrastructure ofthe lingual surface in anguimorph lizardsand snakes: evolutionary and functional im-plications.

In squamates, one of the tongue’s rolesis to collect chemicals from the environment.Both volatile and non-volatile chemicals aredelivered to the vomeronasal chemosen-sory organs (VNOs). The information gainedfrom these chemicals allows squamates tofind and identify mates and prey items. Giventhe tongue’s central role in delivering chemi-cals to the VNOs, understanding the surfacetopology of the tongue and how it might af-fect the tongue’s ability to retrieve environ-mental chemicals and deliver them to theVNOs is of high import. This study focuseson anguimorph lizards and snakes, whosetongues have become highly modified fortheir role in chemoreception. Snakes arewidely believed to have evolved from withinthe Anguimorpha. Both scanning and trans-mission electron microscopy where em-ployed. The surface topology of the forkedregion of the tongue (the tines) differs fromthat of posterior, unforked region of thetongue in all specimens investigated to date.The surface topology of the tines in snakesdiffers significantly from those of anguimorphlizards. In snakes, the tine surfaces are cov-ered with microfacets. However, in mostanguimorph lizards both the dorsal and ven-tral surfaces are covered depressions and

the ventral surfaces have scattered small or“incipient” microfacets. Helodermatids arean exception in that instead of scattered in-cipient microfacets on the ventral surfacesof the tines there are clusters of larger, snake-like, microfacets. Ultrastructural features sug-gest that the deeply forked tongues of snakesand varanids were derived independently.Biomechanical evidence suggests that ul-trastructural differences may be unrelatedto function.

P1.57FINKLER, M.S.*, SUGALSKI, M.T.,CLAUSSEN, D.L., Indiana UniversityKokomo, New England College, Henniker,NH, Miami University, Oxford, OH. Sex-re-lated differences in locomotor performanceand metabolism in breeding spotted sala-manders (Ambystoma maculatum).

We investigated differences in metabo-lism and locomotor performance of male andfemale spotted salamanders collected dur-ing the breeding season. Male salamandershad faster voluntary crawling speeds thandid females (both gravid and non-gravid).Burst swimming velocity was higher in malesthan in gravid females, but there was no dif-ference in burst crawling speeds betweenthe sexes. Oxygen consumption was greaterin females both during rest and during loco-motion at the voluntary crawling speed ofgravid females. Both male and nongravidfemales sustained locomotion longer thandid gravid females. These findings suggestdifferences in locomotor performance andenergetics that may account for observeddifferences in arrival times at breeding sitesand survival between male and female molesalamanders.

60.3 FISH, F.E., FRAPPELL, P.B.,BAUDINETTE, R.V., MACFARLANE, P.M.,West Chester University, La Trobe Univer-sity, Melbourne, University of Adelaide, LaTrobe University, Melbourne. Energetics ofterrestrial locomotion of the platypus: meta-bolic inefficiencies due to aquatic adapta-tion.

The platypusOrnithorhynchus anatinusdisplays specializations in its limb structurefor swimming which could negatively impactits terrestrial locomotion. Platypuseslocomoted on a treadmill at speeds from 0.19

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to 1.08 m/s. Video records were used for gaitanalysis and the metabolism of terrestriallocomotion was studied by measurement ofoxygen consumption. Platypuses used walk-ing gaits (duty factor < 0.50) with a sprawledstance. To limit interference from the exten-sive webbing on the forefeet, the platypuseswalked on their knuckles. Metabolic rate in-creased linearly over a 2.4-fold range withincreasing walking speed in manner similarwith terrestrial mammals, but was low due tothe relatively low standard metabolism of themonotreme. The cost of transport decreasedwith increasing speed to a minimum of 0.71J/N m. When compared to the cost of trans-port for swimming, the metabolic cost for walk-ing was 1.89 times greater. This differencemeans that the platypus pays a price in ter-restrial locomotion by being more aquati-cally adapted than other semiaquatic or ter-restrial mammals.

S11.1FISH, F.E., West Chester University,PA. Mechanisms for enhanced maneuver-ability in organisms of varying flexibility.

Maneuverability with respect to turningis critical to the performance of fast swim-ming animals. Turning is effected by dynamicforces. For many aquatic animals, theseforces are dominated by steady non-inertialforces including lift and drag. Animals canuse an asymmetrically applied drag to ro-tate and turn. Appendages modified aspaddles can produce this effect which workswell in conditions dictated by low velocity,continuous turning and precise control, butincurs a high energy cost. Lift-based maneu-vering systems have the advantage of pro-ducing a centripetal force to effect turningwithout incurring a large decelerating drag,but are limited in duration. Animals that usedrag-based turning possess rigid bodies witha high degree of stability. Lift-based turningis associated with a flexible body or enlargedcontrol surfaces. Flexible bodies possessedby fish and marine mammals have beenshown to permit high levels of performancewith respect to turning rate, centripetal ac-celeration, and turn radius. Rigid bodies doconstrain turning performance, however, theinability to bend can be compensated for bythe use of appendages and vectored thrustmechanisms.

64.3 FISHER, G.R.*, DIMOCK, R.V. Jr.,Wake Forest University. The role of the larvalmantle cells during metamorphosis ofUtterbackia imbecillis (Bivalvia: Unionidae).

Larvae of Utterbackia imbecillis undergoa period of metamorphosis to the juvenilewhile parasitic on a host fish, but can alsobe induced to metamorphose in a modifiedcell culture medium. This metamorphosisinvolves some dramatic changes in the struc-ture of the larval mantle cells which arethought to be involved in digesting the de-generating larval adductor muscle and thehost fish tissue. Transmission electron mi-croscopy and histochemistry for digestiveenzymes were used to investigate the roleof these cells in both fish-reared and in vitro-reared animals. TEM analysis revealed en-docytosis in the larval mantle cells but not inany other larval tissues. This was true evenfor in vitro-reared animals which presum-ably ingest the larval adductor muscle sincethere is no fish tissue present. Fish-rearedlarvae showed no acid phosphatase activ-ity; however, the larval mantle cells of in vitro-reared larvae possessed lysosomes con-taining acid phosphatase and were also re-leasing acid phosphatase into the extracel-lular environment at cell boundaries. The dif-ferences in acid phosphatase activity be-tween the two rearing conditions may be dueto the presence of glycogen in the fish-rearedanimals. Prior to the onset of metamorpho-sis, larvae possess large amount of glyco-gen stores in the tissues. In the in vitro-rearedanimals, these stores are depleted very earlyin metamorphosis, while in fish-reared ani-mals they remain until much later. Perhapsthe acid phosphatase is not activated untilthe cells have used up their glycogen re-serves and require an external source ofnutrition. It appears that the larval mantle cellsplay a role in the digestion of both the larvaladductor muscle and host fish tissue duringmetamorphosis.

33.1 FOLK, D.F.*, BRADLEY, T.J., Univer-sity of California, Irvine. How does selectionfor desiccation resistance affect the distribu-tion of water in Drosophila melanogaster?

We are conducting experiments with fivepopulations of Drosophila melanogaster,which have undergone laboratory selection

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for increased desiccation resistance for over200 generations. For each population ofdesiccation-resistant flies (D flies), a controlpopulation (C flies) was maintained underidentical conditions, except that C flies hadad libitum access to water. Previous studieshave demonstrated that increase in desic-cation resistance in D flies is associated withincreases in bulk water content and reduc-tion in cuticular permeability to water. Wetested two hypotheses concerning acquisi-tion and storage of bulk water in the desic-cation-tolerant populations: (1) that reduc-tion in post-eclosion diuresis in the D fliesallows flies to accumulate more water earlyin the adult phase and (2) that the greatestportion of surplus water is stored in thehemolymph. Our results indicate that rate ofurine elimination up to 4 h post-eclosion wasnot differentiated between the D flies andtheir controls. Differences in post-eclosiondiuresis have, therefore, not evolved duringselection for increased desiccation resis-tance. Analysis of water distribution in thebody of the flies demonstratedthat the D flieshave a statistically significant, 3.4-fold in-crease in hemolymph volume. On average89% of the extra bulk water in the D flies isstored in the hemolymph. We are currentlyexamining the significance of the extracel-lular location of this water on mechanismsof water use during desiccation in fruit flies.Funded by NSF Grant IBN9723404.

S4.7 FORWARD, R.B., Duke UniversityMarine Laboratory. Ontogentic changes incrustacean larval behavior: contributions totransport and metamorphosis.

Larval development of many estuarinedecapod crustaceans occurs in coastal/oce-anic areas. Thus, larvae are transported sea-ward from estuaries for development andthen shoreward and up-estuaries to nurs-ery areas as post-larvae. This paper will fo-cus on selective tidal stream transport(STST) as the mechanism for horizontalmovement in estuarine areas. The behaviorunderlying STST varies with species and isbased on either a biological rhythm in activ-ity or behavioral responses to environmen-tal factors associated with tides. Transport ofpost-larvae terminates upon settlement and

metamorphosis in nursery areas. Both posi-tive (e.g. odor from conspecifics and aquaticvegetation) and negative (e.g. ammonium,hypoxia, predator odor) cues for habitat se-lection and metamorphosis will be consid-ered.

37.3 FOUGEROLLE, M.F.*, TURINGAN,R.G, Florida Institute of Technology,Melbourne, Florida Institute of Technology,Melbourne. The effects of prey type on thefeeding biomechanics of Archosargusprobatocephalus.

Ubiquitous species in heterogeneous,coastal habitats typically encounter variableprey-resources. The biomechanical basisfor the ability of A. probatocephalus to con-sume both soft and hard prey organismswithin its environment was examined in anattempt to understand the mechanisms thatunderlie the abundance and distribution ofthis species. Fish from the same locationwithin the Indian River Lagoon were rearedunder two diets: whole bean clams (Donaxgouldii) [hard prey] and D. gouldii with shellsremoved (soft prey). At the end of a 70-dayrearing period, fish were measured for keybiomechanical features of the prey-captureand processing mechanism. Analysis of Co-variance revealed that biting muscles andbones of fish fed hard prey were more mas-sive than fish fed soft prey. For a given bodysize, estimated biting strength of fish rearedin hard-prey diet was greater than fish rearedin soft-prey diet. Total body mass and me-chanical advantage of the feeding mecha-nism did not differ between diet treatments.We hypothesize that the ability of A.probatocephalus to consume different preyorganisms is associated with its ability to al-ter the development of its feeding mecha-nism. Phenotypic plasticity appears to be oneof the mechanisms that underlie a speciesability to exploit locally available prey-re-source.

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P1.14FOURNIER, F.*, KARASOV, W.H.,MEYER, M.W., University Laval, UniversityWisconsin-Madison, Wisconsin DNR. Theeffect of feather development on the phar-macokinetics and oral bioavailability of me-thylmercury in common loon chicks.

Mercury is known to preferentially bindto structures containing sulfhydryl groups(e.g. keratin in growing feathers), and thelatter affinity may influence the accumula-tion and excretion of ingested mercury ingrowing birds. We therefore determined theeffect of feather growth on the pharmacoki-netics and oral bioavailability of methylmer-cury in common loon chicks (Gavia immer)as part of an ongoing research project aimedat elucidating the ecological risk of mercuryto loons. Oral bioavailability was determinedby comparing the blood concentrationthrough time after oral (500 MICROg/kg bodymass) and intravascular (IV; 200 MICROg/kg body mass) administration at two ages(35 and 84 days) during postnatal develop-ment (during and after feather growth). Thearea under the blood concentration-timecurves extrapolated to infinity (AUC) werecalculated from the orally and IV-dosedchicks using the trapezoidal method.Bioavailability was estimated as the ratio ofthe dose-corrected oral AUC to the IV AUC.Bioavailability differed between ages and itwas 77% at age 35 days and 92% for 84day old chicks. We determined pharmacoki-netic parameters by fitting a two-compart-ment non-linear regression model to bothconcentration-time data sets, and this re-sulted in models that accurately predictedthe initial rapid distribution phase and thelinear excretion phase for both data sets (r2

> 0.9 in all cases). The excretion rate con-stant differed between ages and was foundto be 0.006 and 0.048 day-1 for chicks aged35 and 84 days, respectively. The meanelimination half-life of methylmercury in loonchicks was determined as 14 and 116 daysfor chicks aged 35 and 84 days, respectively.These results suggest that growing feathersare an important excretory route for ingestedmercury.

P2.24FOWLER, E.*, HILL, P.S.M., Universityof Tulsa, OK, University of Tulsa, OK. Indi-vidual identification of the prairie molecricket, Gryllotalpa major.

Gryllotalpa major, the prairie mole cricket,is a rare species native to the Oklahomagrasslands. Little is known about this par-ticular species, and information is difficult toobtain because of its subterranean lifestyle.Of particular concern is our not being able tomark individuals in a population to trackmovements or gauge individual mating suc-cess. This study was designed to distinguishindividual males based solely on their air-borne sexual advertisement calls. The malesdwell within their own burrow systems in theground and project their calls through a sur-face opening of an acoustic horn to attractfemales for mating. Cassette tape record-ings were collected from targeted burrowsduring the calling season and coverted todigitized sound files using SIGNAL software.These files were then subjected to correla-tional analyses to determine if we could dis-tinguish “same” from “different” with a highlevel of accuracy and repeatability. Athoughother studies of insect sounds in this contexthave not been reported, recent success inidentifying individual canaries, bats, wolves,etc. encouraged us to pursue this work. Withthe certainty of identification based on thecall, new doors can be opened to the studyof this and related species. Not only will malespacing and burrow establishment be opento new interpretation, but parameters of thecalls of successful males can be examinedto tease out the focus of female choice forthe species.

26.1 FRANCIS, JR., A.W.*, TURINGAN,R.G., Florida Institute of Technology,Melbourne, Florida Institute of Technology,Melbourne. Functional implications of asym-metrical feeding biomechanics inpleuronectiform fishes.

Flatfishes (Order Pleuronectiformes) dif-fer from the generalized teleost morphologyin that bilaterally symmetrical larvae meta-morphose into bilaterally asymmetrical ju-veniles where one eye migrates to the op-posite side of the head. The development ofmorphological asymmetry is expected to

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have profound consequences for flatfishfeeding biomechanics, performance, andecology. Biomechanical features associatedwith feeding in developing summer floun-der, Paralichthys dentatus, were measuredfor both ocular (left) and blind (right) sides.Using principles from mechanical engineer-ing, the measurement of lever arms respon-sible for lower jaw depression and eleva-tion allowed for the determination of me-chanical advantage for each side of the head.Mechanical advantage was then used tomake functional predictions about feedingmode where the oral jaw lever system infishes represents a compromise betweenspeed of jaw movement and strength of bite.Analysis of variance or analysis of covari-ance revealed significant differences in le-ver arms and mechanical advantage be-tween sides of the head of late metamorphicand early juvenile summer flounder. In par-ticular, the ocular side is predicted to have afaster bite while the blind side is predicted tohave a stronger bite. Work currently inprogress will test predicted functional asym-metry using high speed recordings of feed-ing kinematics in developing flatfish.

37.5 FRANK, C.L., Fordham University. Thenutritional ecology of food hoarding by redsquirrels.

It has proposed that granivory and foodhoarding coevolved repeatedly in mammalsbecause seeds tend to retain their nutritionalquality during storage, although this hypoth-esis has not been tested. The effects of pro-longed storage on the nutritional composi-tion of five conifer seed species hoarded byMount Graham red squirrels, Tamiasciurushudsonicus grahamensis, were examinedin order to better understand the evolutionof food storage. The results demonstrate thatthe nutritional quality of all conifer seed spe-cies examined decreases during storage byred squirrels, and three of the seed speciesno longer met the minimal nutritional require-ments of red squirrels after 3-8 months ofstorage. This study demonstrates that theevolution of food hoarding by red squirrelswas probably actually constrained by thenutritional properties of their primary food.

46.6 FREEMAN, G., University of Texas,Austin. A developmental basis for the Cam-brian explosion: evidence from extant bra-chiopods.

Paleontological evidence indicates thata large number of new animal phyla, in ad-dition to classes and orders within phyla,were first observed during the Cambrian. Onepossible basis for the genesis of new mor-phologies during this period may have beenthe ease with which developmental pro-grams responsible for regional specificationduring early development could be changed.Subsequently these developmental pro-grams are postulated to have become moretightly integrated, making changes in earlydevelopment more difficult to effect andthereby reducing the variation that naturalselection can operate on. Within theLinguliformea and Craniiformea, extantlingulids, discinids and craniids belong toorders that originated during the Cambrian.Within the Rynchonelliformea, extantrhynchonellids belong to the pentameridelineage that also originated during the Cam-brian. The other order, Terebratulida, with ex-tant families, originated via a series of inter-mediate forms, from a pentameride ances-tor at the base of the Devonian. By compar-ing cleavage patterns, fate maps, patternsof morphogenetic movements during gas-trulation, the timing of regional specificationduring early development, and themechansisms responsible for regionalspecification in extant species one can as-sess whether there is more variation in theways of going about early development indescendants of orders that originated dur-ing the Cambrian versus descendants of theTerebratulida which originated later. Thereare major differences in embryogenesis ingroups that originated during the Cambrian.There are essentially no differences in theearly embryologies of the rhynchonellidHemithyris, and two representatives of theTerebratulida, although these forms aremorphologically disparate.

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2.1 FREUND, E.V.*, DEWAR, H., CROLL,D.A., Harvard University, Cambridge, MA,PIER, Oceanside, CA, University of Califor-nia, Santa Cruz. Locomotor tracking of thespine-tailed devil ray, mobula japanica.

Three-dimensional movements and for-aging ecology of a small manta ray species,the spine-tailed devil ray, Mobula japanica,were monitored using acoustic tracking (n =2) and archival tagging techniques (n = 4) inthe southern Sea of Cortez. The rays rangedin size from 65 - 112 cm disc length (mean =87.6 cm, n = 6) with track duration rangingfrom 21 to 28 hours. Simultaneous biophysi-cal oceanographic profiling allowed exami-nation of temperature profiles and prey dis-tribution in relation to ray movements. Theprimary prey of these rays is krill,Nyctiphanes simplex, which remains atdepth (~150 m) in dense clouds during theday, then moves to the surface and dispersesat night. The rays spent most of their timeabove the thermocline and appeared to for-age at night when the krill swarms approachthe surface. When krill were present theanimals displayed a step-wise ascent pat-tern which may indicate foraging throughclouds of krill. Maximum dive depth duringone track reached 445 m. Consistentthroughout the tracks was a dive and ascentpattern suggestive of burst and glide swim-ming. Tracking speed was typically 1 knotwith bursts up to 4.5 knots. The rays traveledup to 30 miles in 24 hours and did not al-ways remain in areas where krill density washigh. Information on movements and habi-tat use is critical for understanding the im-pact of fisheries on manta ray populations.This impact is potentially high because ofthe mantasí low fecundity rates (~1 pup peryear). In addition to improving our under-standing of their natural history, we hope thisresearch will provide valuable informationwhen management and conservation strat-egies are considered. Supported by Na-tional Geographic.

65.3 FRIEDRICH, M., Wayne State Univer-sity, Detroit. Evolution of insect eye develop-ment: comparative and functional evidencefor a conserved role of Wingless in nega-tively controlling the spatial extent of retinadifferentiation.

Molecular genetic studies in model or-ganisms like mouse and Drosophila haveidentified a number of genes, which appearto be expressed and required in similar waysduring eye development. Fundamental as-pects of metazoan eye development aretherefore likely to be evolutionarily con-served. Nonetheless, Drosophila exhibits ahighly derived mode of insect eye develop-ment from imaginal discs, which may, tosome degree, compromise its suitability foracross phyla comparisons. It is also an im-portant question, which developmental regu-latory changes were involved in the transi-tion from embryonic eye development inprimitive insects to the advanced mode ofpostembryonic eye development in Droso-phila. We are therefore studying eye devel-opment in the more primitive flour beetleTribolium castaneum and the grasshopperSchistocerca americana. We have previ-ously shown that the expression of the sig-naling factor Wingless in front of the differ-entiating retina is highly conserved indicat-ing a conserved function in negatively regu-lating retina differentiation in insects. Con-sistent with this, we find that exposure of invitro cultured grasshopper retinas to lithium,which constitutively activates Wingless sig-naling via inhibition of Glycogen synthasekinase-3, specifically blocks progression ofretina differentiation. A detailed analysis ofwingless expression during Tribolium em-bryogenesis revealed that Wingless is ex-pressed in a manner consistent with a func-tion in suppressing embryonic eye devel-opment thereby allowing only a small num-ber of larval photoreceptors to differentiateand facilitating the delay of adult retina dif-ferentiation into postembryogenesis.

39.1 FRYE, M.A.*, DANIEL, T.L., Universityof Washington, Seattle, University of Wash-ington, Seattle. Mechanical encoding prop-erties of the wing hinge stretch receptor inthe hawkmoth.

Insect flight emerges from complex inter-actions among patterned motor output, mus-culoskeletal mechanics, aerodynamic andinertial forces, and neural feedback. In thehawkmoth Manduca sexta, feedback from awing hinge stretch receptor (SR) is crucial

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for the visuo-motor control of lift. Using a com-bination of extracellular recording, opticaltracking, and high-speed video, we showthat the SR undergoes sinusoidal lengthchanges during tethered flight and fires aburst of spikes near the dorsal stroke rever-sal. We describe the mechanical encodingproperties of the stretch receptor by com-paring experimental data to the output of acomputational model in an effort to betterunderstand how this specialized sensoryorgan encodes forces and strains acting onthe wing hinge. Using a mechanical actua-tor, we measured tissue tension, deforma-tion, and SR spiking activity in response tocontrolled motions of the wing hinge. Stepchanges in tissue extension evoke an initialrapid increase followed by decay in both ten-sion and SR firing rate. These time depen-dent responses were fit to models of the tis-sue and the SR that are comprised of vis-cous and elastic elements. We comparedsimulation output to experimental results us-ing sinusoidal motion stimuli matching thein vivo deformations of thewing hinge. Forsuch motions, the SR encodes timing, am-plitude, and frequency of experimental winghinge deformation. Model results closelymatch tissue tension seen in vitro, howeverthe model does not capture the firing patternof the stretch receptor. Thus, stretch recep-tor responses are not determined by simplelinear models, and non-linear characteris-tics or active encoding dynamics are neededto explain the behavior of this mechanore-ceptor. Supported by NSF.

P2.62A FUDGE, D.S.*, GOSLINE, J.M.,University of British Columbia. Mechanicaland optical properties of hagfish slimethreads.

Hagfishes are unique in their ability toproduce vast quantities of fiber-reinforcedslime when they are provoked. In order tounderstand the material properties of hag-fish slime, we investigated the properties ofisolated slime threads from the Pacific hag-fish (Eptatretus stouti). The threads are manu-factured within specialized cells called GlandThread Cells (GTCs), which are found withinthe numerous slime glands. Each GTC pro-duces a single, continuous, intricately coiled

protein thread that unravels upon contactwith seawater. We found GTCs to exhibit abi-directional taper, being on average 3.0 ±0.4 mm in diameter in the middle, and 1.0 ±0.2, and 1.5 ± 0.2 mm in diameter at the two(distinct) ends. Slime threads were on aver-age 12 ± 0.44 cm long in the unstrained state,but can be as long as 34 ± 1.2 cm whenstrained to the breaking point. Tensile testsof the threads in seawater revealed them tobe quite extensible and strong, and there-fore tough. Average extensibility (DELTA/Lo)in water was 1.8 ± 0.11, strength was 170 ±24 MPa, and toughness was 100 ± 19 MJ/m3. Threads tested in air were stronger, stiffer,tougher, and less extensible than thosetested in seawater. Average extensibility inair was 1.0 ± 0.10, strength was 520 MPa,and toughness was 270 ± 17 MJ/m3. Tensiletests performed in chaeotropic agents suchas guanidine HCl suggest that the IF pro-teins that make up the threads are held to-gether by non-covalent intermolecularforces. Birefringence data and evidence fromCongo Red staining of strained andunstrained threads suggest that the lowmodulus plateau region of the stress-straincurves corresponds to a transformation ofalpha-helical and/or globular domains of theconstituent IFs to a more highly-orderedbeta-sheet crystalline state.

S11.11 FULL, R.J., University of California,Berkeley. Stability and maneuverability insprawled posture, legged locomotion.

Legged animals bounce up and downand side to side as they run. Species thatdiffer in leg number and posture run stablylike sagittal and horizontal plane spring-masssystems. Preflexive mechanisms at the levelof legs permit passive, dynamic feedbackthat can reject rapid perturbations beforesensor-based reflexes and thereby simplifycontrol. A greater number of widely spaced,compliant legs potentially in contact with thesubstrate provide for robust, dynamic self-stabilization. Legs of sprawled posture run-ners produce lateral and opposing groundreaction forces, since these vectors tend tominimize joint moments by aligning alongthe leg axially. Front legs tend to deceleratethe body, while rear legs only accelerate the

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center of mass. All legs tend to push awayfrom the body. Differential leg function insprawled posture runners not only permitsgreater stability, but also greater maneuver-ability. Maneuvers can require minor neuro-mechanical alterations to straight-aheadrunning. A small change in force productioncan generate turning and climbing withoutlarge changes in leg kinematics. A greaternumber of widely spaced, compliant legspotentially in contact with the substrate pro-vide for greater maneuverability because ofan increased opportunity to shift the centerof pressure. Legged animals appear to man-age energy in a way that works with theirnatural dynamics. Principles from sprawledposture runners are being used to inspirethe design of highly mobile, autonomousphysical models ñ robots. Supported byDARPA/ONR N00014-98-1-0747 and ONRN00014-98-1-0669.

S8.1 FULL, R.J., University of California,Berkeley. Bestowing biological inspirationand getting novel insight from engineeringand entertainment.

Discoveries and principles in biology canprovide inspiration for design in robotics,animatronics, animation and architecture.Unique materials and structures, remarkablefunctional relationships and the spectacu-larly effective performance found in naturaltechnologies provide a wealth of ideas. Yet,blind, direct copying of biology is rare andoften fails. Nature provides useful hints atwhat is possible. In most cases, it is morevaluable to use concepts and analogieswhen advantageous. Natureís designs areconstrained by development, history, func-tion and Newtonís Laws. Human creationsoften extend beyond biological capabilitiesand can be made to be more effective. Theflow of ideas is in no way unidirectional. Infact, historically, there has been more trans-fer from engineering, physics and math-ematics to biology than the reverse (Vogel,1998). The conception and construction ofartificial technologies has been extremelyimportant in providing novel hypotheses andinstrumentation to biology. Multidisciplinaryexperiences can benefit biological researchdirectly and indirectly through the fostering

of lateral thinking. The mutually beneficialreciprocal relationships between biology andengineering, computer science and enter-tainment are increasing exponentially. Weare the verge of a revolution in the Age ofIntegration.

S14.2FURLOW, J.D.*, LIM, W., ERMIO, D.J.,CHIELLINI, G., SCANLAN, T.S., Universityof California, Davis, University of California,Davis, University of California, Davis, Uni-versity of California, San Francisco, Univer-sity of California, San Francisco. Molecularmechanisms underlying thyroid hormoneinduced gene expression cascades duringamphibian metamorphosis.

Amphibian metamorphosis is an excel-lent system to understand nuclear receptorfunction during development. Thyroid hor-mone (TH) induces a wide range of mor-phological changes by regulating gene ex-pression via a pair of nuclear receptors, THreceptor ALPHA (TRALPHA) and TH recep-tor BETA (TRBETA). Our laboratory is inter-ested in how this dramatic tissue specifictranscriptional control by TH occurs. Previ-ous expression studies in the frog Xenopuslaevis implicated TRALPHA in adult tissueformation and TRBETA in larval tissue re-sorption. We employed the TRBETA selec-tive agonist GC-1 as a pharmacologicalprobe of TR function. In transfection assays,GC-1 activated Xenopus TRBETA 20-foldbetter than Xenopus TRALPHA, comparedto the natural ligand T3. In GC-1 treated tad-poles, tail and gill resorption was efficientlyinduced with little effect on limb growth. Inaddition, GC-1 preferentially activated asubset of TH-response genes in the tail, in-cluding several protease genes. We are cur-rently screening additional synthetic TH ana-logs, as well as exploring other means tospecifically manipulate TR isotype activity inliving cells. Finally, we are characterizing theregulatory control regions of several TH re-sponse genes in vivo using transgenesis.We have shown that the TH/bZIP promoterdrives green fluorescent protein (GFP) ex-pression in transgenic tadpoles in a propertemporal and spatial pattern. Our initial stud-ies with the fibronectin promoter, a late THresponse gene at metamorphosis, showed

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a high level of GFP expression in gastrulat-ing embryos, as expected. We are now fol-lowing GFP expression driven by wild typeand mutated fibronectin promoter constructsthroughout development.

P3.87GAINEY, JR., L.F.*, CHICOINE, D.,WALTON, J., GREENBERG, M.J., Universityof Southern Maine, Portland, University ofSouthern Maine, Portland, University ofSouthern Maine, Portland, C.V. Whitney Lab,University of Florida, St. Augustine. Hydro-gen sulfide potentiates muscle contractionin clam gills.

When isolated gills of Mercenariamercenaria are treated with 5-hydrox-ytryptamine (5HT), the branchial muscula-ture contracts in a dose dependent manner.Moreover, a second application of 5HT atthe same concentration produces a largercontraction; this effect is mediated by nitricoxide (NO) synthesized in the muscles.Since NO and hydrogen sulfide (H2S) bothmodulate muscle contraction in mammalianvascular smooth muscle and becauseMercenaria is exposed to H2S in the envi-ronment, we investigated the effects of H2Son gill muscle contraction. When gills werepretreated with 10-6 M H2S and then exposedto increasing concentrations of 5HT, the doseresponse curve was shifted to the left andthe maximal contraction increased in com-parison with untreated controls. With 10-6 MH2S, the concentration of 5HT giving a halfmaximal contraction (EC50) was 1.1 x 10-5 Mand the maximal contraction was 32% of theresting length at 10-4 M 5HT. In untreatedgills, in contrast, the EC50 was 2.8x10-5 Mand the maximal contraction was only 12%.Finally, when gills were pretreated with in-creasing concentrations of H2S and thenexposed to 2x10-5 M 5HT, the contractionswere potentiated in a dose dependent man-ner. The threshold for potentiation was 10-10

M H2S, and the effect became maximal be-tween 10-8 and 10-5 M. Supported by grantsfrom the Maine Science and TechnologyFoundation and the University of SouthernMaine (LFG).

P1.62GALE,H.H., Creighton University In-termittent breathing in very large mammals.

Breath holding is common in reptiles.Intermittent breathing also occurs in verylarge mammals; whale, elephant, rhinoceros,hippopotamus, and giraffe. Both groups havelow rates of metabolism. Ectothermy allowsthe low rates of reptiles. Endotherms havehigher metabolic rates that are inversely re-lated to body size. Hence the mass specificmetabolic rate of a 4000 kg elephant is aboutthe same as a 1kg monitor lizard. Low meta-bolic rates are coupled to low breathing fre-quencies, 6 breaths per minute (bpm) forthe elephant and 3 bpm for the lizard. At lowbpm, intermittent breathing reduces the costof ventilation. Continuous slow breathing haslower airflow velocities that decrease the fric-tional resistance to both laminar and turbu-lent flow. But brief rapid discontinuousbreaths use less energy overall becausevery slow respiratory muscle contraction isextremely inefficient. A female African el-ephant weighing about 4000 kg wasvideorecorded during rest. Thoracic move-ments were analyzed frame by frame with apotential accuracy of 1/30th sec. Breath fre-quency, bpm; and the durations of: inspira-tion Ti, expiration Te, and the pauses be-tween breaths Tp; were measured. Averagevalues were; bpm 5.8, Ti 3.1 sec, Te 1.9 sec,Tp 5.1 sec. Breath holding was in the in-spiratory position. Initial observations of rhi-noceros and giraffe were qualitatively thesame, but with higher bpm and shorter du-rations that correlate with smaller bodymasses. This ventilatory pattern is reminis-cent of reptilian inspiratory breath holdingand active expiration of shorter duration thanpassive inspiration. Inspiratory pauses havethe advantage of a larger air volume to drawupon during apnea. Whether the breathingpauses of very large mammals are also atrespiratory system relaxation volume, thusrequiring no muscular effort, remains to betested.

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P3.103 GALIMA, M.*, KELLEY, K.M., Cali-fornia State University at Long Beach, Cali-fornia State University at Long Beach. Rela-tionship between the physiological stressresponse, serum IGFBPs, and growth in thejack mackerel.

Metabolic and somatic growth param-eters were assessed in Trachurussymmetricus subjected to confinement andhandling stressors. Mackerel were caughtoffshore near Catalina Island and placed into50-L circular aquaria for 5 d without furtherdisturbance (“confinement” group) followedby blood serum collection, or they were sub-jected to an additional 30 or 60 min of han-dling stress prior to blood sampling (“han-dling” groups). Controls were caught andimmediately sampled (within 2 min). Con-finement alone increased serum concentra-tions of glucose (>2-fold, p<0.01) and re-sulted in 6-fold elevations in cortisol(p<0.001), as compared with correspond-ing levels in control fish. With the additionalhandling, cortisol concentrations were el-evated yet further as compared with that inthe confinement group (p<0.05 at 60 min),while glucose levels did not show this trend.Serum profiles of the insulin-like growth fac-tor-binding proteins (IGFBPs) exhibitedchanges reflective of a growth-inhibited statein the stressed mackerel, with the greatestmagnitude of such changes evident in theindividuals with the highest cortisol levels.Results thus far suggest that stress-associ-ated cortisol may play an inhibitory role ingrowth via changes in the IGF system. [Sup-port by NSF grant IBN-9600783 & NIH grant#GM50089].

47.4 GALIS, F., Leiden University. Modular-ity and the conservation of characters deter-mined in the phylotypic stage.

The phylotypic stage is the developmen-tal stage at which vertebrates most resembleeach other. In an earlier study we found sup-port for Raff’s hypothesis that the remark-able conservation of the phylotypic stage invertebrates is due to the high number of on-going interactions. Interestingly, the lack ofmodularity of inductive interactions at thatstagemay not only have conserved this em-bryonal stage more than other developmen-

tal stages, but may also have had conse-quences for the conservedness of adult char-acters determined in this stage. Possible ex-amples are the number of digits in amniotesand the number of cervical vertebrae inmammals. Evidence will be discussed. I endby presenting an argument why the absenceof modularity in the inductive interactionsmay also be the root cause of the conserva-tion of the much discussed temporal andspatial colinearity of the Hox genes in thephylotypic stage of vertebrates.

P2.71GALLARDO, L.I.*, NISHIKAWA, K.C.,Northern Arizona University, Flagstaff, North-ern Arizona University, Flagstaff.Ecomorphology and locomotion ofSceloporus.

Comparative analyses of iguanian lizardmorphology have shown that certain bodyproportions are consistently associated withparticular microhabitats. This result suggeststhat a single genus with ecologically diversespecies will exhibit morphological variationreflecting their ecological niches. Morpho-logical measurements were taken from spe-cies of Sceloporus of varied microhabitatspecialization, ranging from ground dwell-ers to saxicolous species. Saxicolous spe-cies, which regularly encounter incline intheir habitat are expected to exhibit a lowerlength ratio between the most distal andproximal joints than ground-dwelling spe-cies. Saxicolous species are also expectedto have proportionally shorter hind limbswhen compared to those of ground dwell-ers. Likewise, locomotor kinematics andperformance variables are expected to cor-relate with ecological niche and morphol-ogy. Prior studies have found that species ofdifferent body proportions exhibit changesin locomotor kinematics on flat versus in-clined substrates. In this study, species ofSceloporus of varied ecomorphologies wererecorded running on horizontal and inclinedsurfaces to determine how the type of ter-rain an animal inhabits affects locomotion.High-speed imaging of lizards running on atreadmill and a stationary track assessedhow incline affects kinematics, accelerationand velocity. Ground-dwelling species on anincline are expected to alter limb posture

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and stride kinematics to a greater extent thansaxicolous species and to exhibit a reduc-tion in locomotor performance.

P3.6 GARB, J.E.*, GILLESPIE, R.G., Uni-versity of California, Berkeley. Parallel pat-terns in the Pacific? A comparison of phylo-genetic diversification in crab spiders(Araneae: Thomisidae) across threePolynesian archipelagos.

Crab spiders of the genus Misumenops(Araneae: Thomisidae) have repeatedly colo-nized and diversified on a number of Pacificisland archipelagos. Depsite the similarityin the geologic formation of the Hawaiian,Society and Marquesan archipelagos, theirendemic crab spider faunas possess re-markably different levels of diversity. Twenty-one crab spider species have been de-scribed from the Hawaiian Islands. Thesespecies are exceptionally diverse in colora-tion, reflecting their specialization of mim-icry onto several different microhabitat types.In contrast, only one species is known fromboth the Marquesan and Society Islands. Inan effort to understand if the different pat-terns exhibited in these three archipelagosis a result of different levels of colonizationsand/or in situradiation, we conducted a phy-logenetic investigation of Polynesian crabspiders using both molecular and morpho-logical characters. The results of a combinedanalysis of morphological and mitochondrialDNA sequence data indicate that althougha greater number of colonization to the Ha-waiian archipelago may partially account forits species richness, the greater levels ofmorphological diversity exhitibed by theHawaiian crab spiders are likely to have re-sulted from rapid in situdiversification.

P3.4 GAREY, J. R., CAMPBELL, T. G.*, Uni-versity of South Florida, University of SouthFlorida. Acanthocephelan and rotifer rela-tionships revisited.

The phylogenetic relationship betweenRotifera and Acanthocephala has been amatter of debate for several years. Althoughthese phyla are clearly related, the exactrelationship between them had proven diffi-cult to determine with only morphologicaldata. Several phylogenetic analyses based

on sequence data have produced trees withAcanthocephala included within Rotiferainstead of as a sister phylum. However, therelationship of Acanthocephala to the threeclasses of Rotifera (Bdelloidea, Seisonidea,Monogononta) has been more difficult toresolve. Some 18S and 16S rDNA studieshave shown Acanthocephala to be a sistertaxon to Bdelloidea, whereas heat shockprotein 82 has placed Acanthocephala as asister group to a clade composed of bothBdelloidea and Monogononta. A more re-cent 18S rDNA study showed Acantho-cephala as the sister group of Rotifera. Sev-eral new 18S sequences for acanthoceph-alans and monogonont rotifers are nowavailable. We are sequencing the 18S genesfrom three additional rotifer species: Thebdelloids Habrotrocha constrictaandAdineta vaga, and the monogonontfloscularid Sinantherina socialis. We presenta phylogenetic analysis of the available 18Srotifer and acanthocephalan sequences.

S7.1 GAREY, J.R., University of SouthFlorida. The lesser known protostome taxa.

Most biologists are familiar with only afew of the approximately 35 extant animalphyla such as annelids, arthropods, mol-luscs, echinoderms and chordates. Howmany are familiar with the more obscuregroups such as gnathostomulids,kinorhynchs, priapulids and cycliophorans?Current advances in evolutionary, develop-mental and ecological studies are now mak-ing it apparent that the lesser known animalgroups are important subjects of study. Thelesser known taxa will be instrumental in test-ing new ideas about the metazoan radia-tion using morphological, molecular and de-velopmental approaches. Many lesserknown groups are far more important eco-logically than is generally known, particu-larly the phyla represented by mostlymeiofaunal (microscopic) species. This sym-posium will be important in renewing inter-est in the lesser known animal groups, inencouraging their use in research and teach-ing, and in promoting the relevance of high-level systematic studies.

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S8.6 GATESY, S.M., Brown University,Providence, RI. Dinosaur feet, pigeon wings,and 3-D animation: entertaining science?

Software developed for the entertainmentindustry is a valuable resource for biologistsand paleontologists interested in studyingmotion. Despite rather steep learningcurves, high-end packages contain toolsideally suited for modeling organic struc-tures, controlling articulated elements, im-porting video/film sequences, and runningdynamic simulations. My lab has been us-ing Studio and Maya software fromAlias|Wavefront to approach the morphologi-cal, spatial, and temporal complexity of limbmovement during locomotion. One projectinvolves reconstructing foot kinematics in210 million year old dinosaurs based on fos-sil trackways from Greenland. Many of thetracks were made by theropods sinking toconsiderable depth, thereby causing thesubstrate to intercept and preserve footmovements in 3-D. Tracks are simulatedusing a NURBS model foot skeleton, whichemits particles as it passes through a vol-ume of “sediment” of variable depth. Re-constructed stance phase movements arethen modified to produce tracks matchingthe fossil data. A second project focuses onbird flight. Accurate measurement of wingjoint angles has remained elusive due tothe 3-D complexity of the wingbeat cycle. Byrotoscoping a NURBS model pigeon overframes of high-speed X-ray film, skeletalmotion can be simultaneously animated andquantified. This methodology allows a wing’sreal (rather than “realistic”) motion to be ana-lyzed at an unprecedented level of resolu-tion, yielding both animations and data. Sup-ported by NSF, Brown University, andAlias|Wavefront.

P1.46GEHNRICH, S.G.*, HENRY, R.P.,WEIHRAUCH, D., TOWLE, D.W., SalisburyState University, MD., Auburn University, AL.,Lake Forest College, IL., Mount Desert Is-land Biological Lab, ME. Identification of car-bonic anhydrase isoforms in the gills of theshore crab, and changes in their expressionduring acclimation to low salinity.

At low salinity, the epithelium in the pos-terior gills of the shore crab, Carcinus

maenas, is believed to take up chloride andsodium from the environment in exchangefor intracellular bicarbonate and protons,which are generated within the cell by theenzyme carbonic anhydrase (CA). Duringacclimation to low salinity, CA activity in theposterior gills increases during the first 96hours of exposure, whereas CA activity inthe anterior gills does not change signifi-cantly. Most of the increased CA activity isfound in the cytoplasm, with a smaller in-crease associated with the microsomal frac-tion. Using RT-PCR we have identified andpartially sequenced two isoforms of carbonicanhydrase from the posterior gills of theshore crab. These isoforms share severalhighly conserved, CA-specific, amino acidresidues with mammalian isoforms, but haveonly a 30% amino acid homology with eachother. Isoform-specific PCR primers weredesigned, and the levels of mRNA for eachisoform was determined by quantitative PCR.Although mRNA for both isoforms was de-tected, one of the forms is expressed in muchgreater amounts than the other. During ac-climation to low salinity, levels of mRNA forboth isoforms increased approximately 2.5-fold, reaching maximal levels after 48-72hours. Future studies will be done to deter-mine the specific sub-cellular location of eachisoform, and their exact role in ionic homeo-stasis. Supported by NSF (IBN-9807539)and Mt. Desert Island Biological Lab.

P1.8 GEIS, A.*, WIBBELS, T., MARQUEZ,M.R., GARDUÑO-D, M., BURCHFIELD, P.,PEÑA-V, J., University of Alabama at Bir-mingham, University of Alabama at Birming-ham, Instituto Nacional de la Pesca, InstitutoNacional de la Pesca, Gladys Porter Zoo,Texas, Gladys Porter Zoo, Texas. Evaluationof hatchling Kemp’s ridley sex ratios usingnest incubation temperatures at RanchoNuevo, Mexico.

The Kemp’s ridley sea turtle,Lepidochelys kempi, is the most endangeredsea turtle in the world. It possesses tempera-ture-dependent sex determination (TSD) inwhich the incubation temperature of the eggdetermines the sex of the hatchling. Past stud-ies have suggested that TSD has the poten-tial of producing highly biased sex ratios,

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which may not be advantageous to the re-covery of endangered sea turtle populations.Therefore, it is of great importance to moni-tor hatchling sex ratio production in nestingbeach conservation programs. The primarynesting grounds of the Kemp’s ridley is lo-cated on a stretch of beach near RanchoNuevo, Mexico, where an international con-servation effort (coordinated by InstitutoNacional de la Pesca) monitors all nestingand relocates all nests to protected areas(i.e. egg corrals). During the current study,nest temperatures were monitored in rela-tively large numbers of nests over three nest-ing seasons (1998-2000). This includedmonitoring nests in three different egg cor-rals throughout each of the nesting seasons.Temperature data from the initial two yearsof this study suggest that a majority of thenests produced mostly or all females, indi-cating an overall female bias for the 1998and 1999 nesting seasons. We are currentlyanalyzing the data from the 2000 nestingseason. The biased sex ratios predicted dur-ing the current study exemplify the need tomonitor hatchling sex ratios produced in seaturtle conservation programs. Such informa-tion is a prerequisite to the development ofeffective management strategy for endan-gered populations.

S2.6 GHEDOTTI, M., Regis University Un-paired fins: derived genitalia in fishes.

A review of the diversity of genitalia de-rived from unpaired fins in actinopterygiianfishes is presented. The modifications of theanal fin and urogenital region amongactinopterygiians are morphologiacally quitevaried. The most commonly known and bestunderstood anal-fin derived genitalia arethose of the cyprinodontiform fishes. How-ever, median-fin derived genitalia are foundin a wide range of distantly relatedactinopterygiian taxa. This variation in mor-phology provides an existing reservoir ofinformation concerning the developmentalmechanisms associated with the formationof a genital region along the body axis. Likenatural teratology or experimental perturba-tion of development, natural variation amongtaxa provides valuable information concern-ing basic developmental patterns and pos-sible developmental outcomes.

S6.3 GIBB, A. C., DICKSON, K. A., NorthernArizona University, Flagstaff, California StateUniversity, Fullerton. Functional morphologyand biochemistry: is there a correlation be-tween metabolic enzyme activity and swim-ming performance?

Many animals, including marine fishes,are difficult to study in their natural habitat.Consequently, little is known about their rou-tine behavior and locomotor performance.Comparative physiologists and ecologistshave searched for a specific morphological,physiological or biochemical parameter thatcould be easily measured in a captive, fro-zen, or preserved animal, and that wouldaccurately predict the routine behavior of thatspecies in the wild. Many investigators havemeasured the levels of activity of specificenzymes involved in energy metabolism inthe body musculature of marine fishes, gen-erally assuming that high specific activitiesof enzymes involved in aerobic metabolismare indicators of high levels of aerobic per-formance and of sustained swimming abil-ity and that high activities of anaerobic meta-bolic enzymes indicate high levels of burstswimming performance. In this paper, wereview the comparative data that support thishypothesis. Perhaps more importantly, weoutline recent studies we have conductedthat specifically test the hypothesis that lev-els of enzyme activity in the myotomal mus-culature of fishes correlate with locomotorperformance. In these studies, we combinedthe fields of biochemistry and functional mor-phology by measuring enzyme activities andswimming performance in the same indi-viduals and comparing this relationshipacross several different species. Finally, wesuggest areas of further investigation thatmay provide biochemical indices that areaccurate predictors of animal performance.

45.3 GILBERT, S.F.*, LOREDO, G.A.,BRUKMAN, A., TUAN, R., Swarthmore Col-lege, Thomas Jefferson University,Swarthmore College, Thomas Jefferson Uni-versity. Studies in turtle shell development:osteogenesis of an evolutionarily novelstructure.

The turtle shell is an evolutionary nov-elty, a development of the osseous skeletonunique among vertebrates. The turtle shell

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is composed of a dorsal carapace, a ventralplastron, and a lateral bridge. The carapacecontains fifty unique bones, while the plas-tron contains nine bones. In the carapace,the most dorsal bones are formed by theneural portion of the spine, while the costalbones are formed from the dermis betweenthe ribs. The marginal bones form along theedges of the shell mesoderm. The ribs be-come trapped in the carapacial ridge (CR),a structure resembling the limb bud. Weshow that the mesoderm of the CR ex-presses fgf10. FGF10 is found in the limbbud where it acts as an agent of cell prolif-eration and chemotaxis. In the carapace, theneural bones and the nuchal bone are thefirst new bones to be seen. Meanwhile, theanterior ribs show an expanded region ofbone around them, and the ribs appear tobe inducing new bone from the dermisaround them.By 120 days, the ossifying der-mal regions between the ribs have coa-lesced. The future plastron can be identifiedby nine ossification centers in the ventral der-mis. No alcian blue staining is seen presag-ing these sites. The three ossification cen-ters corresponding to the three anterior plas-tron bones will fuse first, and the six mar-ginal ossification centers of the plastron growtoward each other and fuse. Condensedmesenchyme presages the advance ofthese spicules. The bony spicules cross themidline, but avoid fusing until later in devel-opment. We are presently attempting to iden-tify the paracrine and transcription factorsregulating the development of these evolu-tionary novel structures.

P3.14A GILCHRIST, M.A.*, SASAKI, A.,Duke University, Fukuoka University. Host-parasite coevolution based on models ofwithin-host dynamics.

Host-Parasite coevolution has long beenan area of interest of evolutionary biologists.However, most mathematical models on theevolution of parasite virulence view the hostas a static, non-evolving entity. By focusingon the dynamics of the parasite populationwithin a host and by coupling these dynam-ics with a simple model of the host’s immuneresponse, we are able to simultaneouslyexplore the evolutionary dynamics of both

the host and the parasite. Our findings indi-cate that there is a single evolutionary stableequilibrium towards which the systemevolves. Furthermore, the impact of the dis-ease on host survivorship and parasite fit-ness at the equilibrim is a function of its lo-cation which in turn is a function of the costof the host’s immune response and theamount of damage caused by each unit ofparasite growth.

P2.29GILCHRIST, S.L., New College of USF.Resetting the system: dynamics of hermitcrab shell cycling after Hurricane Mitch.

An eight-year study at Bailey’s Cay hasrevealed a dynamic shell cycling systembetween hermit crabs on the coral reef, inbackreef seagrass, and on land. Predatorssuch as octopuses, crabs and fish consumeboth hermit crabs and gastropods on the reef.Birds, crabs, and flies eat terrestrial hermitcrabs and gastropods. Typical shell cyclingis from the reef to land with little movementin the opposite direction. Hurricane Mitchhovered near the Cay, scouring the reef withsand, depositing sand in seagrass areas,and submerging the island for 3 days. Com-parisons of shell use patterns, populationsizes and distributions of hermit crabs andtheir predators before and after Mitch showconsistency in shell types used and remark-able persistence of shells within the system.Predators are of nearly uniform year classas are several species of hermit crabs. Her-mit crab visits to artificial and natural preda-tion sites increased in frequency after Mitchthough “quality” of shells occupied appearedhigher than those used by crabs in previousyears.

61.2 GILLIS, G.B.*, BIEWENER, A.A.,Harvard University, Harvard University. Plas-ticity in limb muscle function during locomo-tion.

Studies of musculoskeletal function invivo during vertebrate locomotion have typi-cally focused on muscles performing a spe-cific role over a limited range of activities. Asa result we currently have little appreciationfor the breadth of function some musclesmight exhibit over a broader range of activi-ties. Using sonomicrometry and electromyo-

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graphy, we investigated patterns of activa-tion and strain in the vastus lateralis and bi-ceps femoris of rats during walking, trottingand galloping across different grades, andduring swimming. During locomotion overground, EMG bursts generally occupy thefirst 60-70% of the stance phase, and in-crease in intensity with increased speed orgrade. Decreased grades lead to decreasesin EMG intensity, particularly in the biceps,which exhibits little or no activity during down-hill locomotion at any speed. During swim-ming, both muscles exhibit substantiallyshorter (about 30% of the propulsive phase),but more intense, EMG bursts. Total fasciclestrain is higher during walking, trotting andswimming (0.21-0.26) than during gallop-ing (0.15-0.17). Moreover, patterns of lengthchange vary from nearly sinusoidal duringswimming, to more complex waveforms onland. Finally, alterations in strain and stimu-lation in the vastus appear to change itsmechanical role during locomotion. Duringwalking, trotting and galloping (non-leadlimb), the vastus is active mostly while iso-metric or during lengthening, however, dur-ing swimming or galloping (lead limb), it isactive largely during shortening. Thus, thesame muscle can shift from absorbing en-ergy to generating energy, depending on gaitor environment. These results indicate thatsome muscles in the rat hindlimb can ex-hibit substantial plasticity with respect to theirgross function during locomotion.

61.1 GIRARD, I.*, MCALEER, M. W.,RHODES, J. S., GARLAND, T., Jr., Universityof Wisconsin-Madison. Increased intermit-tency of locomotion in house mice selec-tively bred for high voluntary wheel running.

After 21 generations of artificial selectionfor increased wheel running, female housemice (Mus domesticus) from replicate se-lection lines demonstrated greatly increasedvoluntary locomotion on running wheels (cir-cumference 1.12 m; Behav. Genet., 1998,28:227-237), compared with individuals fromrandom-bred control lines (L.S. Mean ± SEof wheel running on day 6 of a 6-day test:selection = 10,846 ± 2,023 rev/d; control =2,444 ± 551 rev/d). In nature, many animalsuse intermittent locomotion, which, in labo-

ratory studies, has been shown to increasedistance endurance as compared with con-tinuous exercise. We hypothesized that in-creased intermittency may have evolved inthe lines of mice selected for high wheel run-ning. To describe detailed patterns of run-ning, we videotaped wheel running on day6 of a 6-day test. For each mouse (n = 41),we analyzed 5 minutes of videotape in whichthe mean running speed (revs per 1-minuteinterval) was 75-100% of the maximum rpmobserved over the entire day 6. Proportionof time spent running did not differ betweenanimals from selected and control lines. Se-lection-line females ran significantly morefrequently (7.8 ±1.2 bouts/min), faster (41 ±3.0 rpm while actually running), and inshorter bouts (9.9 ± 2.5 sec/bout), as com-pared with controls (3.4 ± 1.2 bouts/min; 20± 1.1 rpm; 16.8 ± 2.5 sec/bout). Running boutswere interrupted by the mouse coasting orexiting the wheel: inter-bout pauses wereshorter in selection-line (2.7 ± 0.6 sec) thanin control-line (7.4 ± 0.6 sec) females. Be-cause selection-line females may be run-ning at speeds near their aerobic threshold,intermittency in locomotion may be a keyfeature allowing the increased wheel-run-ning performance of these mice. NSF IBN-9728434 and NIH P30 HD03352.

P3.104 GLENNEMEIER, K.A., DENVER,R.J.*, University of Michigan, Ann Arbor,University of Michigan, Ann Arbor. A physi-ological mediator of the response to intraspe-cific competition in Rana pipiens tadpoles.

Competition is known to decrease growthand development rate in larval anurans, butthe physiological mediators of this responsehave not been identified. We measuredwhole-body corticosterone content in Ranapipiens tadpoles raised at two different den-sities and three food levels. Both limited foodand high density were associated with sig-nificantly elevated corticosterone content.Within the medium and low food treatments,high density decreased tadpole growth andslowed development, while within the highfood group, high density was associated withgreater growth and accelerated development(possibly an Allee effect). Lower food levelsconsistently slowed growth and develop-

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ment. Blocking corticosterone synthesis withmetyrapone (MTP) reversed the effect ofdensity on growth but not development anddid not change the effect of limited resourceson growth or development. Thus, corticos-terone appears to mediate the effect of in-creased density on tadpole growth. Theseresults are consistent with developmentalstudies that have shown high doses of ex-ogenous corticosterone to affect growth butnot development in pre-metamorphic tad-poles. Identification of such proximate me-diators of tadpolesí responses to their envi-ronment adds to our understanding of am-phibian physiological ecology and couldimprove and simplify predictions about spe-cies interactions and their community-leveloutcomes. (Supported by the Great LakesEnvironmental Protection Fund and NSFGrant IBN9974672).

1.1 GOLDMAN, E.B.*, DANIEL, T. L., Uni-versity of Washington, Seattle, University ofWashington, Seattle. Material propertiesshape dynamical responses of hydrozoanjellyfish.

Radially symmetrical and composed ofacellular mesoglea, two cell layers, and aprimitive nervous system, jellyfish are an el-egantly simple launching point to investigatehow material properties of the musculoskel-etal system shape the dynamics of locomo-tion. Mesoglea, composed of mucopolysac-charides, collagen, and water, has a char-acteristic nonlinear response to an appliedstrain. This study asks how suchnonlinearities determine the dynamical re-sponse of a jellyfish’s simple geometry sub-ject to periodic forcing. We compare thestrain-dependent stiffness of mesoglea be-tween three species of jellyfish, Mitrocomacellularia, Polyorchis penicillatus, andAequorea victoria, each with a distinctiveoverall shape. Because of the nonlinear andtime-dependent behavior of mesoglea, wemeasure the complex modulus by record-ing its stress in response to sinusoidal strainsat a variety of frequencies and mean lengths.Using a simple power law to fit the resultantrelationships between complex modulusand mean length, we describe the strengthof nonlinearity in mesoglea by the size of

the exponent. Aequorea victoria, a jellyfishwith unevenly distributed mesoglea and un-usual swimming kinematics, has the high-est mesoglea exponent, making it the moststrongly nonlinear, while Mitrocomacellularia, a jellyfish with a relatively simplegeometry and typical swimming kinematics,has the lowest . The exponent describingthe mesoglea of Polyorchis penicillatus fallsin between, although it more closely re-sembles Aequorea. Armed with these esti-mates, we use a simple dynamical model toshow that very subtle changes in the strengthof the nonlinearity are manifest as signifi-cant changes in the spectral responses ofthe musculoskeletal system to periodic forc-ing.

P3.66 GOLEMAN, W.L.*, URQUIDI, L.J.,MCMURRY, C.S., ANDERSON, T.A.,KENDALL, R.J., CARR, J.A., Texas TechUniversity, Lubbock, Texas Tech Univer-sity, Lubbock, Texas Coop. Fish and Wild-life Res. Unit, Texas Tec, The Inst. ofEnivron. and Human Health, Texas Tech,The Inst. of Enivron. and Human Health,Texas Tech, The Inst. of Enivron. and Hu-man Health, Texas Tech. Amphibian meta-morphosis is inhibited by environmentallyrelevant concentrations of ammonium per-chlorate.

Ammonium perchlorate (AP, NH4ClO4)has been used as an oxidizer component insolid rocket propellants for more than 50 yrs.AP detection in surface and ground watersnear aerospace materials storage areas, aswell as the fact that perchlorate inhibits thy-roidal iodide uptake, suggests that environ-mental AP may disrupt thyroid activity in hu-mans and wildlife. Here we describe AP ef-fects on development and metamorphosisin Xenopus laevis. Eggs and larvae wereexposed to a range of AP concentrationsand control medium for 70 days. AP inhib-ited thyroid-hormone-dependent aspects ofgrowth and metamorphosis in a reversiblemanner. Preliminary findings indicate thatenvironmentally relevant concentrations ofAP inhibit tail resorption as determined bythe EDSTAC Tier I test for thyroid hormonedisruption. These effects were observed atconcentrations at or below those reported in

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surface waters at the Longhorn Army Am-munition Plant in Karnack, TX. Our resultssuggest that, at these concentrations, APmay pose a threat to normal development innatural amphibian populations. (The viewsand conclusions contained herein are thoseof the authors and should not be interpretedas necessarily representing the official poli-cies or endorsements, either expressed orimplied, of the 311 HSW/AFIERA or the U.S.Government. Supported in part by the U.S.Department of Defense, through SERDP un-der a Cooperative Agreement with the USAF,Inst. for Environ, Safety, and Occup. Health,Brooks AFB, TX).

46.1 GOLENBERG, E.M., Wayne StateUniversity. Floral developmental regulationand sexual lability in spinach.

In dioecious, cultivated spinach, Spinaciaoleracea, the presence or absence of re-productive organs is determined by organprimordia initiation rather than by degenera-tion of existing organ primordia as found inmaize, sorrel, and campion. Male and fe-male flowers differentiate morphologicallyearly in floral morphogenesis (stage 2) whensepal primordia are formed. Hence, sexualdetermination is established before stamenor carpel primordia are formed and appearsto follow canalized developmental path-ways. Two lines of evidence demonstratethat sexual dimorphism in spinach is deter-mined by facultative regulation of sex spe-cific genes. First, we have determined by insitu hybridization that spinach B class ho-mologs, SpAP3 and SpPI, are expressedthroughout the male floral meristem beforestamen primordia are formed, then. subse-quently, become restricted to stamen primor-dia. Expression of either gene is not detect-able in any stage of female flower develop-ment. This implies that sex determination oc-curs at or upstream of B class gene expres-sion, and that downstream targets of the Bclass genes will be differentially expressedin males and females. This also implies thatthese expression patterns may control thedevelopment of sexual dimorphism in spin-ach. Second, in two cultivars, 30-40% ofpotentially female plants develop as maleswhen GA3 is applied, indicating that sex de-

termination can be regulated upstream ofthe organ identity genes. Furthermore, a thirdcultivar does not exhibit a male bias in re-sponse to GA3, indicating that genes up-stream of the normal organ identity genesdetermine sex and are polymorphic. Theseresults suggest that sexual lability itself canpotentially evolve in this species.

P1.96GORDON, S.D.*, STEVEN-SON, R,University of Colorado, Boulder, Universityof Massachusetts, Boston. Long-term massgains relative to meal size and sugar con-centration in two species of butterflies, Pierisrapae and Manataria maculata.

We investigated how the concentrationof sugar in artificial nectar affects meal sizeand changes in body mass of Pieris rapae,a widely dispersed common Pierid speciescaptured in Boston, MA and Manatariamaculata, a long-lived fruit eating tropicalSatyrine species captured in Monteverde,Costa Rica. Butterflies were kept in labora-tory cages and had limited opportunity foractivity. The initial mass (mg) and wing length(mm) were recorded for each individual. Ona daily basis, five (Pieris) or six groups(Manataria) of 5-7 individuals were fed spe-cific sugar water concentrations ranging from0 to 50% by weight until satiated. Body masswas recorded both before and after feeding.Groups offered pure water took in the small-est meal sizes averaging about 5% of theirbody mass. In contrast, the groups fed atapproximately 10% took in the largest massper meal, averaging 16% for Pieris and 55%for Manataria. At higher sugar concentra-tions, meal size declined in both species,however groups fed between 40% and 46%took in the largest amounts of sucrose permeal. Over the duration of the trials, groupsfed between 38% and 40% sugar watergained the most weight, roughly 85% for thePieris (20 days) and just under 13% for theManataria (7 days). Both the species thatfed on water alone lost mass. The resultsaddress ecological implications (water bal-ance, metabolic rate, condition indices) andraise questions about physiological limita-tions (meal size, long term mass gain) foreach species.

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S15.6GRASMAN, K.A., Wright State Univer-sity. Assessing immunological function intoxicological studies of fish-eating birds.

Persistent organochlorine contaminants,especially polychlorinated biphenyls (PCBs)and 2,3,7,8-tetrachloro-P-dioxin (TCDD),have been shown to suppress immune func-tion in rodents and chickens in the labora-tory. Fish-eating birds are exposed to highlevels of organochlorines in some ecosys-tems. Our objective was to assess the ef-fects of organochlorines on immune func-tion of young wild herring gulls (Larusargentatus) and Caspian terns (Sternacaspia) from the Great Lakes and blackguillemots (Cepphus grylle) from Labrador.Immunological status was assessed in 3-4week old chicks using general indicators(white blood cell counts and immune organmasses) and specific tests of immune func-tion (the phytohemagglutinin (PHA) skin testfor T cell function and the anti-sheep redblood cell (SRBC) antibody test for humoralimmune function). An intradermal injectionof PHA into the wing web was used to stimu-late a T cell dependent reaction that wasmeasured 24 h after injection. An intrave-nous injection of SRBC was used to stimu-late an antibody response that was mea-sured in plasma 6 days after immunization.In all three species, suppression of the PHAtest was strongly associated with organochlo-rine exposure. This suppression of T cellfunction was consistent with thymic atrophyobserved in guillemot chicks and herring gullchicks and embryos. In Caspian tern chicks,the antibody response was positively asso-ciated with PCBs and 1,1-dichloro-2,2-bis(P-chlorophenyl)ethylene (DDE). These im-mune function tests can be adapted to abroad range of species and have proven tobe feasible in toxicological and physiologi-cal studies of wild birds.

P3.79GRASSO, F.W.*, BASIL, J.A., Brook-lyn College, Brooklyn NY. Antennule mor-phology and olfactory sampling strategy: les-sons from the lobster.

The six, paired cephalic appendages ofdecapod crustaceans provide sensory in-formation to the highest centers of the brain.These bear sensory organs devoted to one

primary and a number of secondary sen-sory modalities and allow these animals toactively probe and investigate their environ-ment. Of these the antennules are special-ized to provide chemical and rheotactic in-formation. . We performed a morphologicalsurvey of 30 representatives of thePalinuridae (spiny lobsters). Across thesespecies we found a 27-fold variation (esti-mated from morphology) in volume sampledby the olfactory sensilla (the aesthetascs)on these appendages. This contrasts withnegligible variation in Nephophidae (clawedlobsters) and Scyllaridae (slipper lobsters)of comparable body size. We also found thatthe length of the antennules the covered bythe aesthetascs on 23 species of spiny lob-sters from the genus Panuluris does not scalein proportion to antennule length; the ratiodecreased with increasing antennule length.Because the aesthetascs are located at thedistal tips of the antennules, we suggest thatthe observed variation in olfactory samplingvolume serves to increase the range of two-point discrimination rather than to increasethe total receptor surface. We speculate thatthe variation may be accounted for by theflow regimes typical to each species niche.

28.4 GREAVES, W.S., University of Illinoisat Chicago. Modeling the location of themammalian tooth row.

A previous study suggested that mam-malian tooth rows should be confined to theanterior seventy percent of total jaw lengthbecause that situation maximized the aver-age bite force along the jaw. In the studydescribed here, an estimate of the distancebetween the right and left tooth rows wasdetermined using a similar analysis. For asample of tooth rows in different hypotheti-cal locations, relative bite force was plottedfrom the first incisor at one end of each toothrow to the third molar at the other end. Inte-grating the equations of these bite force plotsgave the area under each curve. (The areaunder the curve is a measure of the sum ofall the bite forces along any given tooth row.)This sum was then divided by the length ofthe jaw, from joint to incisor, giving the aver-age bite force along an entire jaw. In thismodel, the location of the hypothetical tooth

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row where this quotient was largest de-pended upon the ratio of the jaw width (fromjoint to joint) to the jaw length (along the mid-line from joint to incisor). Jaw width is be-tween sixty and eighty percent of jaw lengthIn many mammals. The model predicts thatfor animals with a W : L ratio within this range,the distance between the right and left toothrows, measured at the molars, will be be-tween fifty and sixty-three percent of the dis-tance between the two jaw joints.

66.5 GREEN, A.K.*, WARD, D., Universityof Wisconsin, Madison, Ben Gurion Univer-sity of the Negev, Israel. Dispersal ofhemiparasitic mistletoe (Plicosepalusacaciae) by the yellow-vented bulbul(Pycnonoyus xanthopygos) among Acaciatrees in Israel.

Infection by the mistletoe (Plicosepalusacaciae) may exacerbate the already lowand infrequent recruitment of Acaciaraddiana, A. tortilis, and A. gerrardiinegevensis (<1%) trees in ephemeral rivervalleys (wadis) of the Arava valley, Israel.Yellow-vented Bulbuls (Pycnonotusxanthopygos) were shown to be the primary,if not sole, dispersal vectors of this mistletoe.Bulbuls removed the fruit’s protective exo-carp, swallowed the pulp-covered seedwhole, and defecated the viable, viscin-cov-ered seed (% germination of defecatedseeds=50.0%; n=66 seeds). Foraging ob-servations during summer, fall, and winterindicated that mistletoe fruits were con-sumed when present, but were a substan-tial portion of the diet (>70% of foraging at-tempts) only when fruits were abundant inthe late fall. Bulbuls spent most of their timeperched in Acacia trees (range: 55%-92%).We combined data on bulbul movementsbetween Acacia host trees with data on tran-sit times of mistletoe seeds (range: 4-55 min;Mean±S.D. = 19±4 min; n=10 bulbuls) to cre-ate a probability distribution of seed deposi-tion as a function of distance from the parentmistletoe plant (seed shadow). The seedshadow indicated that a mistletoe seed isdeposited on the same host tree as the par-ent plant only 4% of the time. The modal dis-persal distance is 40-50m (>13% probabil-ity), and the maximum distance is 270-280m

(< 1% probability). These data show that thebulbul provides quality, directed dispersalfor mistletoe. The increasing population ofbulbuls following the increase in agricultureand human settlements in this region couldfurther spread P. acaciae and enhance thethreat to the long-term survival of Acaciapopulations in the Arava valley of Israel.

S9.4 GREENBERG, N. B., University of Ten-nessee. Causes and consequences of thestress response in reptiles.

Real or perceived changes in the envi-ronment of a lizard can evoke adaptive be-havioral responses that are coordinated bythe neural and endocrine mechanisms ofthe stress response. Acute responses, in-volving catecholamines released in varyingproportion at different sites along their sym-pathetic pathways may interact with and becomplemented by chronic responses involv-ing the hypothalamic-adrenocortical system.The central and systemic consequences ofthese actions include apparent changes inaffect and motivation. These changes resultin altered responses to environmental stimuliincluding the social stimuli that male andfemale conspecifics may provide. This re-view will collate and summarize the resultsof a program of research into the neural andendocrine causes and consequences ofspecific behavioral patterns seen in the smalldiurnal lizard, Anolis carolinensis. I will thenattempt a synthesis that will hopefully illumi-nate the manner in which autonomic reflexescome under the influence of environmentalstimuli and attain significance as social sig-nals.

34.3 GREENLEE, K.J.*, HARRISON, J.F.,EGBERT, K., Arizona State University, Tempe.How does the respiratory response to hy-poxia change throughout ontogeny in agrasshopper and a caterpillar?

As insects age, body size can increasedramatically. For example, grasshoppers(Schistocerca americana) grow to 100 timestheir original mass, and larval tobacco horn-worms (Manduca sexta) increase an impres-sive 7,000-fold from hatchling mass. Howdo these increases in size affect the functionof the insect respiratory system? To explore

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the relationship between body size and gasexchange, we used insects (S. americanaand M. sexta) of known age and body size,exposed them to graded hypoxia, and mea-sured MCO2 (umol/h) using flow-throughrespirometry. We hypothesized that largerinsects would tolerate hypoxia better thansmaller insects due to an increased usageof convective gas exchange. As predicted,larger grasshoppers had much lower criti-cal PO2 ís (the PO2 at which MCO2 becamesignificantly lower than that in normoxia) andhad an increased ability to enhance abdomi-nal pumping in response to hypoxia. TheMCO2 of small grasshoppers decreased al-most logarithmically with PO2, supporting thehypothesis that smaller grasshoppers relymore on diffusion for gas exchange. In con-trast, caterpillar body size had no effect oncritical PO2, suggesting that tracheal oxygendelivery capacity matches the increased tis-sue needs for oxygen across all sizes. Wealso hypothesized that caterpillars wouldhave relatively high critical PO2 ís due to theirlack of visible respiratory movements andbecause reported critical PO2 ís for fly andbeetle larvae are greater than values foradults and pupae. However, critical PO2 ísfor M. sexta were low and similar to thosefound for S. americana adults (near 5 kPaO2).

P2.4 GREGG, C.S.*, NELSON, P.G.,TUCKER, M.C., GRASSLE, J.P., RutgersUniversity, New Brunswick, NJ. Developmentof a DNA probe for the identification of early-stage Mercenaria mercenaria (hard clam)larvae.

Early-stage bivalve larvae are extremelydifficult to identify unequivocally using mor-phological methods because they lack di-agnostic characteristics. As part of a studyof larval transport of estuarine bivalves, anoligonucleotide probe was developed foridentifying Mercenaria mercenaria larvae.The 18S rRNA gene from M. mercenaria wassequenced and compared with other bivalvespecies, including four species (from differ-ent genera) within the family Veneridae. A25 base-pair region of the gene was identi-fied that was unique to the genusMercenaria. Subsequent tests using dot-blot

hybridization revealed that the probe boundonly to the Venerid species M. mercenaria,M. campechiensis, and Venerupisphilippinarum. The method of using DNAprobes with dot-blot hybridization for theidentification of larvae should prove usefulfor small-scale studies where accurate iden-tification of larvae is necessary.

S7.7 GRENIER, J.K., EraGen Biosciences.Minor phyla fill the gaps: priapulida andonychophora.

The advent of comparative moleculardatabases has generated new hypothesesabout animal phylogeny that are reshapingour understanding of animal evolution. Forexample, the bilaterian phyla are now oftengrouped into three major clades, the deu-terostomes, the lophotrochozoans, and theecdysozoans. The Ecdysozoa include sev-eral phyla that were once classified aspseudocoelomates (nematodes, priapulids)in addition to arthropods and ony-chophorans. The proposed Ecdysozoanclade is supported by molecular evidenceincluding ribosomal RNA sequence and thepresence of characteristic Hox genes. Oneprimary value of a redesigned (and hope-fully more accurate)animal phylogeny, in-cluding the placement of phylogeneticallycryptic minor phyla within the animal tree, isthe implication for evolutionary comparisonsand reconstructions. The so-called minorphyla are critical for establishing ancestralconditions, both molecular and morphologi-cal, at interesting nodes in animal phylog-eny. Further, these phyla contribute to theanalysis of evolutionary changes in genefunction during animal evolution. For ex-ample, priapulids and onychophorans fill inthe gaps in evolutionary comparisons be-tween the model organisms Drososphila(Arthropoda), C. elegans (Nematoda), andthe mouse (Chordata). These and other mi-nor phyla help us to interpret the ongoingexperiment that is animal evolution.

61.3 GRIFFIN, T.M.*, GARCIA, S.,WICKLER, S.J., HOYT, D.F., KRAM, R., Uni-versity of California, Berkeley, CaliforniaState Polytechnic University, Pomona, Cali-fornia State Polytechnic University,Pomona, California State Polytechnic Uni-

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versity, Pomona, University of Colorado,Boulder. Determinants of the walk-trot tran-sition and preferred walking speeds: in-sights from intra-specific size comparisonsof horses.

Much of our understanding of the effectsof size on locomotion has come from inter-specific size comparisons (i.e. mouse-to-el-ephant). To control for phylogenetic and mor-phological differences associated with in-ter-specific comparisons, we used intra-spe-cific size variation within horses to under-stand the determinants of the walk-trot tran-sition (W-T) and preferred walking (PW)speeds. We addressed two questions: 1) AreW-T and PW speeds determined by invertedpendulum mechanics? 2) Do W-T and PWspeeds minimize the metabolic cost re-quired to travel a unit distance? We studied9 horses (Equus caballus) spanning an 8-fold range in mass (90 - 720kg) and a 2-foldrange in leg length (0.7 - 1.4m). W-T speedsand rates of oxygen consumption weremeasured during treadmill locomotion. PWspeeds were measured during overgroundwalking. To compare inverted pendulum me-chanics across size we calculated the Froudenumber, = v2/gL, where v is forward speed(m/s), g is gravity, and L is leg length. Wefound that the absolute W-T speed increasedwith size (1.6 to 2.3 m/s), but occurred atnearly the same Froude number (0.34). TheW-T speed concurred with the metabolicallyoptimal transition speed. The absolute PWspeed increased with size up to 400kg (0.9to 1.5 m/s) but curiously did not increasefurther. The PW speed coincided with theminimum metabolic cost of transport, exceptin the smallest horses that preferred slowerthan energetically optimal speeds. In gen-eral, W-T and PW speeds are tightly coupledto both inverted pendulum mechanics andmetabolic energy minimization. Supportedby NSF IBN-0073020, NIH S06 GM53933and NIH AR44688.

P3.57GRINDSTAFF, J.L., Indiana University,Bloomington. Dietary protein restriction doesnot suppress humoral immune function ormaternal antibody transfer in Japanese quail(coturnix coturnix japonica).

The ability to resist infection is an impor-tant component of survival and lifetime re-

productive success. Many current theoriesin ecological immunology assume thatmounting and maintaining an immunologi-cal defense is energetically costly and nutri-tional resources expended on immune func-tion may necessarily be traded-off with otherfunctions including reproduction. Femalespassively deposit antibodies in egg yolk dur-ing egg formation that provide the sole formof humoral immune defense for newlyhatched young. To determine the influenceof dietary protein on reproduction and hu-moral immunity in adults and passive anti-body transfer to eggs, I maintained adultJapanese quail (Coturnix coturnix japonica)on isocaloric diets containing either the rec-ommended protein content for reproducingadults (20%) or a low protein diet (12%).Birds fed the low protein diet weighed lessthan control birds, and females producedfewer eggs that were smaller in size. Al-though the weight of females was positivelycorrelated with antibody response to a novelantigen, adult antibody response did not dif-fer between dietary treatments. There wasalso no difference in antibody titer betweeneggs laid by low protein and control females.These results provide the first evidence thatin Japanese quail, humoral immune func-tion is not suppressed in order to divert lim-ited protein resources to reproductive func-tion.

14.3 GRINDSTAFF, R.D.*, PYLES, R.A.,East Tennessee State University Thyroid andprolactin hormones in metamorphic andpaedomorphic species of ambystomatidsalamanders.

The endocrine control of metamorpho-sis, long identified with circulating levels ofthyroid hormone and prolactin, has beenstudied almost exclusively in anurans withlittle research on hormonal control of meta-morphosis among urodeles. Comparisonsof hormone levels in metamorphic and pae-domorphic salamanders should clarify theroles of tetraiodothyronine (T4) and prolac-tin in regulating the structural and functionalchanges associated with metamorphic pro-cesses. This study provides measurementsof circulating thyroid and prolactin hormonesat different ontogenetic stages in three

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closely related species of ambystomatidsalamanders with differing life histories—anobligate paedomorph, an obligatemetamorph, and a facultative paedomorph.Quantification of thyroid hormone was ob-tained by fluorescein polarization immu-noassay, and of prolactin by microparticleenzyme immunoassay. Among speciescomparisons show T4 levels are significantlydifferent in all developmental stages exceptmetamorphosing Ambystoma maculatumand A. talpoideum. Overall T4 hormone con-centrations in A. mexicanum were higherthan those of A. talpoideum in all develop-mental stages, contradicting the assumptionthat obligately paedomorphic species lacka functional thyroid gland. Higher levels ofT4 in paedomorphic species suggests T4-in-duced metamorphic changes are probablyregulated at target tissues, either by control-ling receptor availability or preventing con-version of T4 to triiodothyronine in periph-eral tissue. Our data also show prolactin se-cretion increases as metamorphosis con-tinues in all species, indicating prolactin isunlikely as a primary inhibitor of metamor-phosis.

P1.35GROVE, T.J.*, SIDELL, B.D., Univer-sity of Maine, Orono. Signature motif and fattyacid selectivity of fatty acyl CoA synthetasein Antarctic fishes.

Cardiac and oxidative skeletal musclesof Antarctic notothenioid fishes preferen-tially utilize lipids over carbohydrates astheir main fuel for aerobic metabolism.These tissues further show a marked ten-dency to oxidize mono-unsaturated fattyacids over saturated fatty acids. We hy-pothesize that fatty acyl CoA synthetase(FACS; EC 6.2.1.3) may be the primary sitedictating specificity for oxidation of longchain unsaturated fatty acids innotothenioids. Full-length FACS cDNAsfrom oxidative skeletal muscle ofChaenocephalus aceratus, Gobio-notothen gibberifrons, and Nototheniacoriiceps were identified by RACE PCRand sequenced. Predicted proteins are697-699 amino acids in length, with 66-67% and 66-69% identity to rat and hu-man, respectively. Part of the fatty acid bind-

ing pocket is encoded by a 25-amino acidconsensus sequence or “signature motif,”1DGWLHTGDIGXWXPXGXLKIIDRKK25,which is common to all FACS. This regionfrom three notothenioids, 532DGWLHTGDV/IGKWLPNGCLKITDRKK556, has 76% (N.coriiceps) to 80% (G. gibberifrons and C.aceratus) identity to the consensus se-quence. In all three species examined,the non-polar Ile21 of the consensus se-quence is changed to a polar Thr551 resi-due. This amino acid difference may sig-nificantly impact preference for long chainunsaturated fatty acids. Additional aminoacid substitutions in this binding motif mayalso play a role in determining theenzyme’s specificity for both chain lengthand degree of saturation. These roles willbe examined by site-directed mutagen-esis. Functional studies of the enzymes todetermine substrate specificities are cur-rently underway. Supported by NSF grantOPP 94-21657 and OPP 99-09055 toBDS.

S3.2 GRUBICH, J.R., University of Califor-nia, Davis. Prey capture in actinopterygianfishes: a review of suction feeding motorpatterns with new evidence from anelopomorph fish: Megalops atlanticus.

Suction feeding has long been recog-nized as the dominant mode of prey cap-ture among ray-finned fishes. Elshoud-Oldenhave and Osse (1976) first proposeda triphasic sequence of the suction feed-ing strike: 1) a preparatory phase, 2) anexpansion phase, and 3) a compressionphase. I review the underlying motor ba-sis of these events during suction feedingby summarizing the major evolutionarytrends identified among basalactinopterygians and advanced teleosts.One goal of this review will seek to identifyfunctionally significant motor pattern fea-tures that are associated with majorchanges in the head musculature and link-age mechanics of the actinopterygianskull. Finally, the motor basis of suctionfeeding in the Tarpon (Megalopsatlanticus) will be presented. Phylogeneti-cally, Elopomorphs are positioned inter-mediately between the Osteogloss-

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omorpha and the Euteleostei (Lauder andLiem, 1983) making them an interestingtransitional group among suction feedingteleosts. Morphologically, they lack theprotrusible upper jaw of advanced teleo-sts, but have a highly mobile anteriorlyswinging maxilla. This group has alsomaintained a double coupling of mandibu-lar depression through the presence ofmandibular-hyoid and interopercular-mandibular ligaments. Both these oral jawtraits are shared with the basalactinopterygian fish, Amia calva(Halecomorphi), making comparisons ofsuction motor patterns between these dis-tantly related species particularly interest-ing. Comparisons of Tarpon suction feed-ing motor patterns to previously docu-mented basal and advanced actinop-terygian fishes will revisit the standingparadigm that there is strong motor pat-tern conservation among the three phasesof the suction feeding strike across a broadphylogenetic spectrum.

P1.86GUADAGNOLI, J.A.*, REIBER, C.L.,University of Nevada, Las Vegas. The on-togeny of pericardial organs in the crayfishProcambarus clarkii.

Adult crayfish pericardial organs, as inlobsters are described as emerging from thethoracic nerves and running toward the dor-sal surface of the heart, becoming fine fibersthat eventually take on a beaded form. Trunksemerge between the epimeral plate andspread over a large area of the membra-nous tissue lining the lateral pericardial walland the tissue surrounding the heart liga-ments. The PO are release sites for severalneurohormones. The adult decapod heartis neurogenic, however it has been hypoth-esized that a developing embryo’s heartbeatis myogenic in origin only later becomingneurogenic. While neurogenic drive arisesfrom the cardiac ganglion, the release of neu-rohormones from the PO provides additionalregulation of heart function. The current studyemployed methylene blue staining tech-niques to determine the development of thePO in embryonic crayfish. The heart startsbeating in the Nauplius 4 stage and is pro-truding posteriorly from its future location in

the pericardial cavity. In juveniles the POappear to be even more extensive that thosefound in adult crayfish. The PO is presentduring all three larval instars. At Nauplius 6and 7, the PO appears to be extensive in thecenter and anterior portion of the dorsal cara-pace even though the heart at these stagesis still protruding from the posterior end ofthe carapace. The PO is a site for release ofserotonin. In the lobster, serotonin appearsas early as 10% development, and hasnearly its full complement of serotonergicfibers by 40-50% development. In other in-vertebrate systems, serotonin appears toplay a role in regulating the pattern of devel-opment of neurons and their connections.The appearance of extensive PO during em-bryonic stages when the heart is still myo-genic may imply an additional role for thePO during development.

35.3 GUGLIELMO, C.G.*, PIERSMA, T.,WILLIAMS, T.D., Simon Fraser University,Burnaby, BC, Netherlands Inst. for Sea Re-search, Texel, Simon Fraser University,Burnaby, BC. Flight-induced muscle dam-age and avian migration, evidence from twoshorebird species.

It has often been suggested that birdsundergo processes of repair and physiologi-cal recovery following long distance flights,however exactly what these processes areremains mostly undescribed. High intensity,long duration exercise is known to causemuscle damage, which is a pathologicalphenomenon qualitatively different from themobilization of amino acids as fuel. Acutemuscle damage results in the disruption ofmuscle ultrastructure, leakage of muscle pro-teins into the blood, immune system re-sponse, soreness, edema, stiffness and re-duced strength. Chronic damage may leadto immunosuppression. We investigatedmuscle damage in two species of long-dis-tance migrant shorebirds by measuringplasma creatine kinase (CK) activity. In theWestern Sandpiper (Calidris mauri), a non-synchronous, short-hop migrant, plasma CKwas higher in migrants than non-migrants intwo years of study. Plasma CK was higher inrelatively untrained juveniles making theirfirst migration than in adults. Bar-tailed God-

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wits (Limosa lapponica) migrate relativelysynchronously and make a single 4300km(60 hrs) flight from West Africa to the WaddenSea in The Netherlands. Plasma CK washighest following arrival at the Wadden Seaand declined during the one month stop-over period. Godwits identified as late arriv-als based on plumage characteristics hadsignificantly higher plasma CK than earlyarrivals. In both model systems elevatedplasma CK indicated that muscle damageoccurs during migration. However, the rela-tive increase in CK was modest comparedto that known to indicate loss of function inother animals. High costs of muscle dam-age (e.g. predation risk) could lead to strongselection for mechanisms to avoid it.

5.2 GURALNICK, R.P., University of Colo-rado, Boulder. Reconnecting cell and ani-mal lineages: a synthetic approach tospiralian evolution and development.

Tracing the timing, position, and direc-tionality of all the cell divisions from zygoteup to late development is the study of celllineages. During the late nineteenth andearly twentieth century, American biologistsat Woods Hole pioneered studies of cell lin-eages of spiral cleavers and used the datathey collected in constructing evolutionarydevelopmental scenarios. However, due tothe lack of appropriate analytical frame-works, that data could not be rigorously usedfor either phylogenetic analysis or for test-ing major evolutionay-devlopmental ques-tions. Here, I reanalyze all available cell lin-eage data using modern statistical tech-niques (like phylogenetic analysis). I showthat: 1.) Cell lineage data reconstructs a phy-logenetic hypothesis that similar but not iden-tical to the patterns found in 18S and mor-phological analyses; 2.) 4d, themesentoblast, is a unique cell that speedsup and slows down in both equal and un-equal cleavers; 3.) Some cells that form inthe same quartet at the same point in thecell lineage hierarchy have much lowervariations across all Spiralia, arguing for ar-chitectural constraint or stabilizing selection.

S4.9 HADFIELD, M.G., University of Hawaii,Manoa. Metamorphic competence is a ma-jor adaptive convergence in marine inverte-brate larvae.

Larvae from diverse and unrelated ma-rine-invertebrate phyla are able to rapidlyrespond to environmental cues to settle-ment and to undergo very rapidmetamorphogenesis because they sharethe developmental trait of metamorphiccompetence. This developmental state,characteristic of larvae as diverse as thoseof cnidarian planulae, molluscan veligers,and barnacle cyprids, is one in whichnearly all requisite juvenile characters arepresent in the larva prior to settlement.Thus metamorphosis, in response to moreor less specific environmental cues (induc-ers), is mainly restricted to loss of larva-specific organs and physiological pro-cesses. Competent larvae of two “modelmarine invertebrates” studied in theauthor’s laboratory, the serpulid polycha-ete Hydroides elegans and the nudibranchPhestilla sibogae, complete metamorpho-sis in about 12 and 20 hrs, respectively.Furthermore, little or no de novo gene ac-tion appears to be required for the settle-ment and metamorphosis response inthese species. Contrasting greatly with theslow, hormonally regulated metamorphictransitions of vertebrates and insects, rapidmetamorphosis in marine invertebrate lar-vae is conjectured to have arisen in di-verse phylogenetic clades as a responseto common environmental pressures that fa-vor extremely fast transition from larval loco-motory and feeding modes, adapted to lifein the plankton, to a different set of suchmodes, adapted to life on the sea bottom.

P3.68HAIGWOOD, J.T., PEREZ, M.*,KELLEY, K.M., California State University atLong Beach. Effects of glucagon and gluca-gon-like peptide-1 (GLP-1) on glycemic sta-tus and glucose production in theisletectomized diabetic goby.

In the teleost fish, Gillichthys mirabilis, atotal endocrine pancreatic isletectomy pro-cedure induces hyperglycemia and a hostof other symptoms typical of insulin-depen-dent diabetes mellitus (IDDM). Thus, in theisletectomized (Ix) goby, hepatic delivery of

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all pancreatic hormones is ceased. In con-trast to IDDM in the streptozotocin-treatedrat, in which only insulin is absent and dia-betic hyperglycemia occurs within 12 hr, theIx goby does not express significant hyperg-lycemia until after 10-15 d, suggestive of alack of hyperglycemic action of a pancreaticfactor(s) during this period. Treatment of 7-dIx gobies (not yet symptomatic) with porcineor human glucagon at 1-5 mg/g body weightinduces a significant hyperglycemia com-parable to that in fully diabetic rats or gobies(20 d post-Ix). Similarly, treatment with iden-tical doses of human or coho salmon GLP-1induces a similar hyperglycemic responsein the 7-d Ix goby. When liver explants fromthe glucagon- or GLP-1-treated Ix gobieswere tested in vitro, they were determined torelease glucose at a 2-fold greater rate permg tissue (p<0.05) than liver explants fromuntreated Ix gobies. These data suggest thatglucagon and GLP-1 are diabetogenic fac-tors in the Ix goby capable of enhancinghepatic glucose output. [Support by NSFgrants IBN 9600783, DUE 9651189, & NIHgrant GM50089]

P1.33HAIR, N. L. *, MORRISON-SHETLAR,A. I., CLAIBORNE, J. B., Georgia SouthernUniversity, Statesboro, Mount Des. Detec-tion of Na+/H+ antiporter in the gills of elas-mobranchs: little skate (Raja erinacea) anddogfish shark (Squalus acanthias).

The Na+/H+exchanger (NHE) is a trans-port protein hypothesized to be involved inacid-base regulation across fish gill epithe-lia. Recent studies have shown the presenceof NHE in the gill tissue of two marine teleo-sts, the long-horned sculpin, Myoxocephalusoctodecimspinosus, and the killifish, Fundu-lus heteroclitus. Preliminary results suggestthe presence of this protein in the gills of twoelasmobranchs, the little skate (Rajaerinacea) and the dogfish shark (Squalusacanthias). The aim of this study was to de-tect the protein and use the detected fragmetobtained from these two elasmobranchs todetermine the further cDNA sequence forthe NHE gill from Raja erinacea. The initialfragment was 470 bp in length and found tohave 85% amino acid homology (71% iden-tity) to the NHE2 human isoform and close

identity to the dogfish shark. Rapid amplifi-cation of cDNA ends (3í/5í RACE) was at-tempted using an NHE specific primer, pre-viously developed from the known elasmo-branch sequence, and a universal primer toamplify the skate DNA sequence. We hopeto determine if the near identity of the partialfragment observed in the skate and the dog-fish will be confirmed in the full length se-quence. This research was funded by NSFIBM-9808141 to J.B.C. and A.I.M.S. and byGSU Academic Excellence and Competi-tive Grant to N.L.H.

S5.7 HAIRSTON, Jr., N.G., Cornell Univer-sity. Temporal dispersal: ecological and evo-lutionary implications of prolonged egg dia-pause.

Zooplankton egg banks are the accu-mulation of diapausing embryos buried inthe sediments of many aquatic ecosystems.These eggs, which are analogous life his-tory stages to the seeds of many plants, cansurvive in a ready-to-hatch state for periodsranging from decades to centuries. Theirpresence in ponds, lakes and near-shoremarine environments has substantial impli-cations for the maintenance of biotic diver-sity, both among and within species, and forthe rates and trajectories of ecological andevolutionary change. Their role in maintain-ing diversity derives from the interaction oftwo factors: generation overlap created byprolonged diapause and environmental fluc-tuations that cause different types (speciesor genotypes) to be favored at different times.Hatching of diapausing eggs influencespopulation and community response to en-vironmental change by introducing to cur-rent environments species or genotypes laidat times in the distant past through what canbe thought of as temporal dispersal. A com-pletely different aspect of egg banks derivesfrom the fact that the sediments of lakes areoften structured in historical sequence (withthe most recent sediments on top and pro-gressively older sediments deeper in thelake bottom). When this is the case, dia-pausing eggs extracted from different sedi-ment ages can provide a means of studyingpast changes in community or population-genetic structure. These two distinct aspects

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of egg banks (i.e., their direct impact on eco-logical and evolutionary processes versustheir usefulness in reconstructing historicalchanges), are potentially in conflict becausefor old eggs to hatch, the sediments must beat least partially mixed, but this same mixingdegrades the accuracy of the historicalrecord. Both aspects are possible, however,when sediment-mixing intensity is spatiallyheterogeneous.

S7.10HALANYCH, K.M.*, McHUGH, D.,DAHLGREN, T.G., Woods Hole Oceano-graphic Institution, Colgate University,Woods Hole Oceanographic Institution. Evi-dence that some lesser-known “phyla” areannelids.

In traditional schemes, the Annelida hasbeen classified as the Polychaeta,Oligochaeta, and Hirudinea (the last twocomprising the Clitellata). However, recentanalyses indicate that annelids are muchmore diverse than traditionally believed, andthat polychaetes are a paraphyletic group.Specifically, some lesser-known taxa (pre-viously regarded as “phyla”) appear to fallwithin the annelid radiation. Abundant mo-lecular, developmental, and morphologicaldata show that the Siboglinidae, which in-cludes the formerly recognizedPogonophora and Vestimentifera, are de-rived annelids; recent data from the Elonga-tion Factor - 1a (EF-1a) gene also suggestthat echiurids are of annelid ancestry. Incontrast, two other lesser-known groups ofmarine worms, the Myzostomida andSipuncula, do not appear to be closely re-lated to the annelids. With advances in ourunderstanding of annelid phylogeny, ourperceptions of body plan evolution withinthe Metazoa are being profoundly changed.For example, the evolution of segmentationis probably more plastic than traditionallybelieved.

P1.18HALBROOK, K.E.*, ROER, R.D.,SHAFER, T.H., PIERCE, D.C., BUTLER, K.D.,University of N.C. at Wilmington, Universityof N.C. at Wilmington, University of N.C. atWilmington, Medical University of S.C.. Par-tial purification of a postmolt cuticular gly-cosidase from Callinectes sapidus and itsputative role in mineralization.

We have previously demonstrated amarked change in sugar moieties of glyco-proteins of the cuticle of the blue crab,Callinectes sapidus, between 0.5 and 3 hpostecdysis. The present study has identi-fied a glycosidase that appears in the cu-ticle during the early postecdysial hours. Theenzyme has affinities for p-nitrophenyl de-rivatives of both N-acetylglucosamine andN-acetylgalactosamine. Both activities arecompetitively inhibited by chitobiose, sug-gesting that the enzyme could be a N-acetylhexosaminidase (HexNAcase). Atypi-cal of HexNAcases described to date, thisenzyme has a pH optimum of 7.0. The en-zyme activity is high during the postecdysialperiod coincident with the changes in glyco-protein profiles observed in vivo. Partial pu-rification of the enzyme has been accom-plished by Sephacryl size-exclusion chro-matography followed by Concanavalin A(ConA) affinity chromatography. To test if aHexNAcase might be the causative agent inthe alteration of the glycans and initiation ofcalcification, newly molted crab cuticle wastreated with exogenous HexNAcase. Treat-ing cuticular extracts from crabs at 0 hpostecdysis with exogenous HexNAcasemimicked those changes observed in vivo.Specifically, the enzyme decreased the ConAaffinity of an 83 kDa glycoprotein that bindsto calcite crystals in vitro. Treating pieces of0 h postecdysial cuticle with HexNAcaserendered them capable of nucleating cal-cite in vitro (similar to 5 h postecdysial cu-ticle), while untreated, 0 h controls remaineduncalcified. The data imply a role of the cu-ticular HexNAcase-like enzyme in the initia-tion of calcite nucleation in the newly formedexoskeleton.

1.6 HALE, M.E., SUNY Stony Brook, StonyBrook, NY. Fast start behaviors of fish lackingMauthner neurons.

The paired Mauthner neurons (M-cells)are used by fishes to initiate the C-start typeof startle response. During C-starts, a fishturns rapidly away from an offending stimu-lus with a “C” shaped body bend. Mauthnerneurons may also function in S-starts, inwhich the initial bend of the body is “S”shaped. While the large majority of fish taxa

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have M-cells, in a few species they havebeen secondarily lost. By examining thestartle response of one of these species, thetoadfish (Opsanus tau), this study investi-gates the role of M-cells and other largereticulospinal interneurons in fast-start be-haviors. EMGs of axial, pectoral fin, and jawmuscle and high-speed video of responsesto touch stimuli were recorded. Toadfish werefound to perform both C-starts and S-starts.The C-start behavior was used by toadfishas part of several different behavioral re-sponses. It could follow the stimulus directlyor be preceded by fin movements and lung-ing and biting at the stimulus probe. Thissuggests that C-start behavior can functionin many behaviors without the reflexive M-cell response to the stimulus. While the pat-tern of the toadfish C-start was like that of aM-cell elicited response, aspects of perfor-mance were decreased indicating that thealternative neural mechanisms by which theC-start behavior pattern is generated in toad-fish do not compensate for the lack of largereticulospinal interneurons. S-starts weremore consistent than C-starts with little varia-tion in the response. Toadfish have a shortlatency, high performance S-start behaviorsimilar to that of fishes with Mauthner neu-rons. This suggests that the M-cell may notbe needed for S-start escape behavior. Thiswork was funded by a Grass Foundation Fel-lowship and NRSA MH11861.

48.2 HALL, M.I., SUNY Stony Brook. An-other look at Leuckart’s Law.

Birds have particularly large eyes rela-tive to their body mass when compared toother vertebrates. This has been hypoth-esized to be an adaptation for flight be-cause increases in axial length of the eyeenhance spatial resolution, possibly im-proving an animal’s ability to judge dis-tances, of obvious importance for flight.This hypothesis has been tested in birdsusing estimates of eye size derived fromPlasticine modeling from dry skulls. Herethe hypothesized relationship betweenincreased relative eye size and flight isevaluated using actual measures of eyesize in both bats and birds: Megachiroptera,Psittaciformes, Columbiformes, Pro-

cell iformes, Falconiformes, andStrigiformes. Eyeball axial diameters andthe density of water are used to estimateeye mass, and are then compared to bodymass figures either estimated from winglength or culled from the literature. Thisstudy confirms that Plasticine modelingfrom dry skulls is a reliable method of esti-mating eye mass. It also confirms previ-ous work demonstrating that eye massscales with negative allometry relative tobody mass. Although eye and body massscale with negative allometry in all groupsstudied, the scaling relationships differ be-tween groups. This suggests that taxon-specific factors other than size influenceeye mass. Leuckart’s Law, that swifter mov-ing animals have larger eyes, receivesscant support from these data: Nocturnalityis also an important determinant of largeeyes among birds. Megachiropteran batshave relatively smaller eyes than birds andother nonvolant mammals, such as pri-mates, lagomorphs, many treeshrews, andelephant shrews. Flight per se does notnecessitate relatively larger eyes morethan do other factors, although the rela-tively large eyes of birds remain unex-plained. Extension of this study to fossilrelatives of birds promises to be interest-ing in this regard.

S8.7 HALLETT, M., Mark Hallett Paleoart.Anatomical principles of reconstructing ex-tinct organisms and their uses in entertain-ment art.

Dinosaurs and other extinct organism arerarely known from anatomical systems otherthan the skeletal system. Nonetheless, adetailed interpretation of muscular structureis prerequisite to responsible reconstruc-tions. Detailed muscular reconstructions takeinto account bony landmarks of muscularattachment, but for those muscles that donot leave obvious marks of attachment onbones, or in animals too small to expressheavy rugosities of muscular attachment,artists engaging in paleontological recon-struction necessarily draw on a thoroughconsideration of comparative anatomy.Knowledge of internal organs’ structure isalso critical to correctly proportioning

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organismal reconstructions. This integratedapproach is employed not only in paintedand sculptural reconstructions, but also inmodeling animals for animated andphotorealistic digital films. In the case of ani-mated character design in films like Juras-sic Park and Dinosaur, computer animatorsmust necessarily simplify body motions rela-tive to the actual muscles that made the ani-mals move. However, a thorough understand-ing of the movements produced by actualmuscle groups is necessary before suchsimplification may take place. In film, recon-struction of dinosaurs and other animals logi-cally proceeds to certain aspects of visualdevelopment. Visual development of char-acters and scenes allows the paleoartist toexperiment with a broad range of sugges-tions for character design. Character designencompasses considerations from surfacetexture and coloration to individual andgroup behaviors. Such considerations arenot random. Rather, they, again, derive fromstudies of similarly sized large vertebratesfrom similar environments. Not surprisingly,large mammals often provide a frameworkand guide to speculation regarding dino-saurs.

P1.6 HAMILTON, H.C.*, GAREY, J.R., Uni-versity of South Florida. Applying moleculartechniques to environmental studies ofmeiofauna.

The purpose of this study is to developsequence tags for a set of marinemeiobenthic fauna (meiofauna). We haveshown that DNA of meiofaunal origin canbe extracted directly from sediment samples.We have also shown that primers for the 18SrRNA gene can be used to amplify themeiofaunal DNA while excluding bacterial,plant, and fungi DNA. We cloned and se-quenced the amplified DNA and found thatall clones belonged to meiofaunal organ-isms, mainly copepods and nematodes. Wehave identified the harpacticoid copepodspecies Longipedia helgolandica and alaophontid species, as well as the nema-tode species Metachromadora pulvinata,from sediment samples taken from TampaBay and extracted DNA from isolated speci-mens of the two harpacticoids. The 18S rRNA

gene was PCR amplified from the extractedDNA and sequenced using an automatedsequencer. The 18S rRNA sequence wasthen assembled and aligned. From the align-ment, we have identified a variable loop thatwould be suitable for identifying the specificmeiofauna species. This 20 to 25 base se-quence was used to construct a sequencetag called a molecular beacon. The molecu-lar beacon is a fluorescent molecule con-taining the short target sequence that canbe used to identify species of meiofauna with-out having to sort them from the sedimentand identify them by morphology. The DNAof the meiofauna can be extracted directlyfrom sediment samples and the 18S rRNAgene PCR amplified. The molecular beaconcan then be used to identify and quantifymeiofauna species of interest.

52.2 HAMMER, H.S.*, WATTS, S.A.,LAWRENCE, J.M., LAWRENCE, A.L.,MCCLINTOCK, J.B., University of Alabamaat Birmingham, University of Alabama at Bir-mingham, University of South Florida, Tampa,Texas A&M University, Port Aransas, Univer-sity of Alabama at Birmingham. The effect ofdietary protein concentration on gonad com-position and gametic condition in the seaurchin Lytechinus variegatus.

Ecological studies suggest that nutrition,particularly dietary protein, affects nutrientstorage and reproductive competency.Starved urchins (ca. 36 mm diameter, n=12)were held in replicated (3x) 80 L aquariawith artificial seawater at 21 C and 32 pptsalinity for each diet treatment. The urchinswere fed one of three isocaloric diets con-taining 14 (L), 32 (M) or 50% (H) protein adlibitum for a 10-week period. The mean go-nad index increased from 0.3 to 10.7, 11.3,and 12.7 for the L, M, and H protein diets,respectively. The gonad contained 25.7, 31.2,and 41.2% protein and 47.3, 39.7, and24.6% carbohydrate for the L, M, and H pro-tein diets, respectively. Lipid level averaged19-22 % and did not vary significantly withdiet. Histological evaluation of ovaries sug-gest that females fed a H protein diet hadincreased gametogenic activity in the ger-minal epithelium and larger numbers of ma-ture and maturing oocytes as compared to

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those fed a L protein diet. Similarly, malesfed a H protein diet had increased gameto-genic activity in the germinal epithelium;those individuals fed a L protein diet ap-peared to resorb numerous gametes. Indi-viduals fed a H protein diet had nutritive ph-agocytes containing a hematoxylin-positive,protein-rich cytoplasm; in individuals fed theL protein diet the cytoplasm appeared tocontain dispersed protein granules. Thesedata indicate that the proximate composi-tion of the gonad reflects the composition ofthe diet. Dietary protein affects gametogenicactivity and the composition of the nutritivephagocytes. Funded by Mississippi-Ala-bama Sea Grant.

P1.66HAMMOND, K.A.*, KRISTAN, D.M.,CHAPPELL, M.A., University of California,Riverside. Aerobic performance in deer mice(Peromyscus maniculatus).

Limits to whole-animal performance maybe a result of peripheral effectors, centralsupportive organs, or both (“symmorphosis”).We examined these concepts using aero-bic performance in deer mice (Peromyscusmaniculatus). We correlated the masses ofperipheral (foreleg and hind leg muscles)and central organs (liver, kidney, spleen,heart, lung and gut) with basal metabolicrate and maximal aerobic metabolism dur-ing tread-mill running (BMR and VO2max,respectively). We found that, with the excep-tion of the small intestine, female mice hadconsistently larger guts than those of malemice. Male mice had larger combined legmuscle masses than female mice, but nei-ther fore- nor hind-leg muscle alone was dif-ferent between the sexes. We also foundpositive correlations between foreleg musclemass and heart mass in both sexes. Despitethe large variation in organ and musclemass, and metabolic rates, we found no cor-relations between organ or muscle massand VO2max although there was a positivecorrelation between BMR and hindlegmuscle mass in both sexes. These data indi-cate that increased aerobic performance isnot necessarily predicated upon possessionof increased central or peripheral organs.Because deer mice have high aerobic per-formance at high altitudes, it will be interest-ing to determine if deer mice reared and

tested at high altitude have stronger or dif-ferent correlations than mice reared andtested at low altitudes.

P3.85HAN, D.W.*, WATSON, R.D., Univer-sity of Alabama at Birmingha. Presence andpotential roles of G-proteins in Y-organs ofthe blue crab.

The synthesis of ecdysteroid hormonesby crustacean Y-organs is negatively regu-lated by molt-inhibiting hormone (MIH); aneuropeptide synthesized and released fromeyestalk neurosecretory cells. Several linesof evidence suggest that the suppressive ef-fect of MIH on Y-organ ecdysteroid synthesisis mediated by an increase in intracellularcAMP. To better understand the link betweenMIH receptor occupancy and Y-organ cAMPlevels, we have assessed the presence ofGTP-binding proteins (G-proteins) in Y-or-gans of the blue crab (Callinectes sapidus).We report here the presence of G-proteinsin Y-organs and control (neural) tissue asdetermined by (1) ADP-ribosylation cata-lyzed by bacterial toxins and (2) western blotanalysis using antibodies raised againstmammalian G-proteins. A pertussis toxin(PTX)-sensitive G-protein (~ 45 kD) was de-tected in both thoracic ganglia and Y-organs.A cholera toxin (CTX)-sensitive G-protein (~49 kD) was detected in ganglia, but not in Y-organs. Western blot analysis, using anti-bodies raised against either G-alpha or G-alpha-s, revealed an immunoreactive pro-tein of ~ 49 kD in both ganglia and Y-organs.The combined results indicate that Gi-likeand Gs-like proteins exist in Y-organs andthoracic ganglia of blue crabs. We are cur-rently assessing the functional role of G-pro-teins in ecdysteroidogenesis. Funded byMS/AL Sea Grant (NA86RG0039) and NSF(IBN-9419916).

54.6 HANCOCK, T.V.*, CROCKER, C.E.,GLEESON, T.T., University of Colorado, SanFrancisco State University, University of Colo-rado. Contributions to elevated metabolicrates during recovery, the excess post-exer-cise oxygen consumption (EPOC), in thedesert iguana (Dipsosaurus dorsalis).

Metabolism remains elevated for sometime following vigorous activity inDipsosaurus. This excess O2 consumption

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may be quantified as EPOC, a volume of O2

representing metabolic costs of recovery. Toanalyze these costs, Dipsosaurus (n=25)were run at a maximal treadmill intensity (2.4m/s) for 15 sec while VO2 was monitored.Animals were removed and sacrificed at rest,directly post-exercise or following 3, 10 or60 min of recovery. Hindquarters were im-mediately freeze-clamped and the gastroc-nemius (GAS), red iliofibularis (rIF) and whiteiliofibularis (wIF) were analyzed for ATP, phos-phocreatine (PCr), and lactate (LA) usingHPLC. GAS resting levels measured 8.7 mMATP, 40.3 mM PCr and 4.0 mM LA and weremore similar to wIF than rIF in all measures.Post-exercise ATP decreased 13%, PCr de-creased 78% and LA increased 966%. ATPshowed the greatest decrease in wIF, whilePCr showed the greatest decrease in rIF. PCrand ATP returned to resting levels within 3-10 min, while LA remained above restinglevels for the entire 60 min. VO2 recoveryrequired 44 min and EPOC measured 0.104ml O2/g. Modeling of individual componentsof EPOC indicate the majority of energeticoutlay may be due to phosphagen replen-ishment (28%); glyconeogenic lactate re-moval (42%); and catecholamine stimula-tion (17%). Phosphagen replenishment iscomplete during the first 10 min of EPOCand would require 67% of O2 consumptionduring this time. Glyconeogenesis likely doesnot begin until after this time and would ac-count for 72% of EPOC from 10 to 44 min.This model is sensitive to assumptions of %active muscle, P:O ratios and lactate fatewhich will be discussed. NSF#97240140.

P1.63HANCOCK, T.V.*, GLEESON, T. T.,University of Colorado. The tradeoff betweenendurance and metabolic costs using inter-mittent locomotion in the desert iguana(Dipsosaurus dorsalis).

The elevated O2 consumption (VO2) ob-served during recovery from activity incursadditional metabolic costs to the animal be-yond that seen during activity. These costsare also realized during intermittent activity,alternating exercise and rest, where VO2 ishigh during rest. Utilizing a rapid fatiguingexercise intensity (4x maximum aerobicspeed=1.08 m/s), Dipsosaurus (n=10) wererun for varying durations (5, 15 or 30 sec)

and pauses (1, 2, 4 or 8 x the activity period).Distance capacity, the total distance summedfrom all activity intervals and reflecting en-durance, increased significantly versus con-tinuous locomotion for most protocols. Thelargest increases were seen when the activ-ity period was limited to 5 sec and the pauseperiod was extended to 5, 20 and 40 sec(55, 118 and 193 m). To assess the meta-bolic costs incurred from these regimens en-abling increased endurance, VO2 was mea-sured for six periods of 5 sec activity sepa-rated by either 5, 20, or 40 sec (n=8). Thetotal excess oxygen consumption (TEOC)was measured as the sum of additional O2

consumption during activity, pauses and re-covery. TEOC increased significantly from0.08 to 0.09 and 0.12 ml O2/g, respectively.As animals traveled the same distance forall 3 regimens, the most expensive strategyper distance traveled was also the one whichprovided the greatest endurance. The in-crease in TEOC was primarily due to a sig-nificant increase in O2 consumed duringpause intervals as pause duration increased,while recovery VO2 did not differ significantly.The concomitant increase in enduranceseen is possibly due to a larger repletion ofmetabolites or elimination of end productsduring longer rest periods allowing addi-tional bouts of activity to be performed.NSF#97240140.

S4.6 HAND, S.C., Louisiana State Univer-sity Induction of quiescence and diapauseduring life cycles of aquatic invertebrates:mechanisms and implications.

With one exception, all major animalphyla contain species that display dormancyat certain points in their life cycles, a featurethat affords tolerance to harsh or ephemeralhabitats. Diapause is an obligate, develop-mentally-programmed form of dormancy thatprecedes the onset of environmental insult.Under conditions that normally promote ac-tivity and development, calorimetric/respiro-metric studies have revealed that majormetabolic depressions accompany entryinto diapause in aquatic invertebrates likesponge gemmules and brine shrimp em-bryos. This depression occurs rather slowlyover a period of several days. Release fromdiapause can be promoted by various envi-

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ronmental ques and artificial chemical fac-tors. Metabolism increases 500-fold or more.In contrast to diapause, quiescence is a typeof dormancy directly induced by an environ-mental stress like oxygen deprivation. Datafrom many aquatic species show that survi-vorship under anoxia is proportional to thedegree of metabolic depression. There is asuite of molecular mechanisms underlyingthese metabolic and developmental pat-terns. In the nucleo-cytoplasmic and mito-chondrial compartments, gene expressionis severely depressed at transcriptional andtranslational levels, as assessed by nuclearrun-on and cell-free translation assays. Di-rect measurements of protein and mRNAhalf-lives indicate that macromolecular turn-over is greatly reduced. Stress proteins oflow molecular mass undergo intracellulartranslocation to the nucleus. These and othermolecular changes associated with naturalstates that border on suspended animationprovide clues as to how other cells might beplaced into stasis. (NSF Grant IBN-9723746)

P1.70HANKISON, S.J.*, LEE, R.E., MiamiUniversity, Oxford, Ohio. Water content of thegall regulates susceptibility to inoculativefreezing in larvae of the goldenrod gall fly,Eurosta solidaginis.

We examined seasonal changes in sus-ceptibility to inoculative freezing in larvae ofthe freeze-tolerant goldenrod gall fly,Eurosta solidaginis (Diptera, Tephritidae).During the autumn the goldenrod plantsenesces and the water content of the galldecreases markedly from >50% to near10%. In late September, when galls weregreen and water content was ~ 55%, morethan half of the larvae within their galls frozewhen held at -2.5ƒC for 24 h and nearly alllarvae froze when held -4 or -6ƒC. How-ever, at this time less than 15% of larvaesurvived freezing at -6ƒC. Gall water con-tent decreased to 33% in October and thenumber of larvae that froze at -4 and ñ6ƒCalso decreased though the proportion of lar-vae that survived freezing increased mark-edly. By November, gall water contentdropped to its lowest value (10%) and fewlarvae froze during exposure to subzero tem-peratures. During the winter, rain and melt-

ing snow transiently increased gall watercontent to values as high as 64% whichcaused many larvae to freeze at tempera-tures as high as -4ƒC. However, during pe-riods of no precipitation the gall tissues driedand, as before, larvae were not as suscep-tible to inoculative freezing. These resultsindicate that in nature larvae may freezeearlier in the autumn and/or at higher tem-peratures than would be predicted basedon the supercooling point of isolated larvae.

P2.63HANNAFORD, S.J., University ofPuget Sound. Role of venation in the sup-port and deformabilty of dipteran wings dur-ing flight.

Wing deformations have been shown invirtually all flying animals thus far studiedand are most pronounced during hovering,maneuvering, and slow flight. Despite theuniversality of deformations during flight, thepossible functional significance of such de-formations is a matter of dispute. Some in-vestigators regard the wing as essentiallyrigid, and suggest that effect of wing defor-mations on flight kinematics is negligible.Others investigators have suggested thatsome deformations in wing shape duringflight may actually be necessary to produceadequate net lift and thrust. To gain a betterunderstanding of the role of wing deforma-tions in insect flight, I measured the net lift,thrust, and wing blade strain in a scaledmodel of Drosophila wings during flight. Fivewing morphologies with different wing ve-nation patterns were considered. Increas-ing the stability of the wing via the additionof veins decreased the magnitude of thedeformations in the wing. The morphologi-cal arrangement of the wing veins also af-fected the spatial and temporal patterns ofwing deformations produced during the wingbeat cycle. Additional goals included deter-mining whether varying the wing rigidity af-fected the net thrust and lift produced duringflight and determining if the relative forcesproduced by various Drosophila flight kine-matic patterns were affected by varying thewing venation pattern.

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S12.1HANRAHAN, J.W.* *, ZHU, T.,DAHAN, D., FUNG, S., MEREDITH, J.,PHILLIPS, J.E., McGill University, McGill Uni-versity, McGill University, McGill University,University of British Columbia, University ofBritish Columbia. The cystic fibrosis trans-membrane conductance regulator (CFTR)chloride channel.

CFTR is a phosphorylation-regulatedchloride channel and member of the ATPbinding cassette (ABC) transporter super-family of proteins. There have been no re-ports of CFTR homologues in invertebrateanimals although ABC transporters arefound in virtually all organisms from bacte-ria to humans. The hindgut of the desertlocust Schistocerca gregaria expresses acAMP-activated chloride conductance remi-niscent of CFTR. We carried out preliminaryRT-PCR studies using RNA from this tissue.Several primer sets failed to amplify CFTR-like products. A search of the Drosophilagenome revealed many putative ABC trans-porters but none having the regulatory (R)domain diagnostic of CFTR. Thus CFTR mayhave appeared late in evolution comparedto other ABC transporters and channels.CFTR channels rapidly deactivate in excisedmembrane patches suggesting they may beassociated with a membrane-bound phos-phatase. We tested that possibility using co-immunoprecipitation and crosslinking stud-ies. A monoclonal anti-CFTR antibody co-precipitated PP2C (but not PP1, PP2A orPP2B) from cells stably expressing CFTR.Conversely, a polyclonal anti-PP2C antibodyco-precipitated CFTR from membrane ex-tracts. When cell lysates were exposed tothe bifunctional crosslinking reagentdithiobis [sulfosuccinimidyl propionate](DTSSP), histidine-tagged CFTR (CFTRHis10)and PP2C became crosslinked into high mo-lecular weight complexes that could be iso-lated by chromatography on Ni2+-NTA aga-rose. PP1, PP2A and PP2B were not co-purified. These results suggest CFTR andPP2C exist in a stable complex that facili-tates regulation of the channel. SDS-PAGEand mass spectrometry are being used toidentify the PP2C isoform.

70.1 HARPER, S.L., REIBER, C.L., Univer-sity of Nevada Las Vegas. Deviants of gasexchange: adaptations of the tadpoleshrimp.

Tadpole shrimp Triops longicaudatus in-habiting a rock pool in southern Nevada ex-perience prolonged hypoxia. Diel oxygenconcentrations (Po2) in the pool range from0-20 kPa O2. Tadpole shrimp were rearedunder low (1-3 kPa) and high (10-13 kPa)Po2’s to determine the influence of rearingPo2 on adult responses to hypoxic stress andto determine the regulatory mechanismsemployed by tadpole shrimp to deal withboth chronic and acute hypoxia. Respira-tory surface area is significantly decreasedin animals reared under chronic hypoxia. Thisdecrease is presumably due to limited oxy-gen available to fuel metabolic anabolismand formation of larger respiratory append-ages. Accessory respiratory surfaces, suchas the hindgut, aid in the diffusion of oxygeninto the animal regardless of their rearingenvironment but appear to primarily assistsmaller anaimals in extracting supplemen-tal oxygen. This is ecologically important be-cause smaller tadpole shrimp cannot regu-late oxygen uptake as readily as larger, moremature animals. Ventialtory rates and vol-umes do not change with varying oxygentensions, however, oxygen extraction in-creases significantly under low oxygen con-centrations in both field and experimentalanimals. Tadpole shrimp from the rock poolin Brownstone Canyon appear to be highlyadapted to the low oxygen concentrationsprevalent in the pool.

S12.7HARRISON, J.F., Arizona State Uni-versity, Tempe. Renal and respiratory mecha-nisms of acid-base regulation in grasshop-pers.

In 1961, J.E. Phillips first provided datato support the hypothesis that active, regu-lated secretion of acid by the grasshopperhindgut functions as a pH regulatory mecha-nism. Subsequent studies by Phillips andco-workers, and our laboratory have stronglysupported this hypothesis. First, it is clearthat insects in general, and grasshoppers inparticular have a strong need for acid-baseregulation. Grasshoppers experience strong

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variation in acid-base loading due to varia-tion in diet, body size (metabolic rate) andfeeding state, yet regulate hemolymph acid-base status closely. Ingestion of plant sec-ondary compounds (terpenes) also stronglymodifies acid-base excretion, probably dueto metabolism and subsequent excretion ofingested compounds. Second, the hindgutappears to have a dominant role in acid-base regulation of grasshoppers. In grass-hoppers, the ventilatory system regulatesinternal PCO2, and feedback mechanisms as-sociated with this process contribute to acid-base homeostasis. However, the bulk of therecovery in extracellular pH in response tononvolatile acid-base challenges occurswithout changes in ventilation or hemolymphPCO2. Diets which are associated with in-creased fecal acid excretion are associatedwith more acidic hindgut lumens, but similarp’s in other sections of the gut lumen. Injec-tion of acid into the hemolympH is associ-ated with compensatory variation in the gutlumen of the Malpighian tubules, ileum andrectum. We used chromium and cobaltEDTA as markers of in vivo fluid flow, andthen estimated acid secretion by the variousgut segments from fluid flow rates, lumenbuffer values, and the pH change associ-ated with acid injection. These estimatessuggest that the bulk of acid-base regula-tion in response to injection of acid into thehemocoel can be attributed to variation inhindgut acid-base transport.

P1.2 HARTMAN, M.J.*, STANCYK, S.E.,University of South Carolina, Columbia. Dis-tribution of an invasive anomurandecapod,petrolisthes armatus,in the northinlet-Winyah Bay National Estuarine Re-search Reserve on the South Carolina coast.

Petrolisthes armatus is a filter-feedingcrab which appears to be extending its rangenorthward along the southeast coast of theUnited States. P. armatus is native to Braziland has been reported from Florida, Missis-sippi, Georgia and Charleston, South Caro-lina. Recently, P. armatus was found in theNorth Inlet-Winyah Bay National EstuarineResearch Reserve (NERR) 60 miles northof Charleston, but it has not been detectedin Murrells Inlet, 20 miles further north. Thisis a preliminary and ongoing project to study

the distribution and biology of P. armatus inthe North Inlet-Winyah Bay NERR and tomonitor its northward movement. Samplingof P. armatus is conducted by randomly se-lecting sites on oyster bars in subtidal andlower intertidal zones and placing five 0.135m2 trays filled with oyster rubble at each zone.Trays are collected after one month and allP. armatus individuals are counted, sexedand measured for carapace width. Samplesfrom July 2000 at three sites in North Inletyielded an average of 34.8 individuals/m2 inthe subtidal zone (range: 0-103/m2)and 70.4individuals/m2 in the intertidal(range: 0-370/m2). Sex ratios were male-biased in bothtidal zones: 1.5:1 subtidal and 1.7:1 inter-tidal. Future studies in the laboratory andfield will examine substrate preference,movement of P. armatus over tidal cycles andbehavioral interactions between xanthidcrabs and P. armatus.

S15.2HATCH, K.A.*, PINSHOW, B.,SPEAKMAN, J.R., Ben Gurion University ofthe Negev, Ben Gurion University of theNegev, University of Aberdeen. Stable iso-topes in exhaled CO2 and the assessmentof substrate metabolism in flying birds.

It is difficult to measure metabolic sub-strate use in flying birds. Indirect calorimetrycan be used for short periods of time in windtunnels but is not easily used in the field.Blood metabolite concentrations have be-come increasingly popular as indicators ofmetabolic substrates in freely flying birds.However, measuring blood metabolitesdoes not directly measure metabolic sub-strate use. We suggest that the applicationof stable isotope analysis offers a more di-rect method of measuring metabolic sub-strates, particularly when applied in concertwith the measurement of blood metabolites.Stored body lipids are depleted in 13C rela-tive to the diet, whereas carbohydrates arenot. Consequently, breath CO2 reflects themetabolic substrate at sampling time. Wehave demonstrated in trained tippler pigeonsthat naturally occurring 13C /12C ratios in ex-haled CO2 provide a measure of the relativecontribution of carbohydrates and lipids toflight metabolism. Manipulating isotope sig-natures in the diet promises to increase theusefulness and resolution of this method.

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71.1 HATLE, J.D.*, BORST, D.W., ESKEW,M.R., JULIANO, S.A., Illinois State Univer-sity Maximum titers of vitellogenin and stor-age protein occur during the canalized phaseof grasshopper oogensis.

Many organisms meet the challenge ofunpredictable environmental conditions byremaining developmentally flexible early intheir development and only later enter acanalized (inflexible) phase of development.Our ultimate goal is to understand the physi-ological mechanisms that underlie this strat-egy in a clutch-laying grasshopper(Romalea microptera). We examined the re-lationships of protein titers and the transi-tion from flexible to inflexible reproduction.Titers of both storage proteins (SPs) andvitellogenin (VG, a precursor of yolk protein)are low in the first half of the oviposition cycleand increase to maxima in the second halfof the cycle. To produce defined canalizedphases, we raised hoppers on four diets thatvaried in their quantity of food: 1) high; 2)high switched to low; 3) low switched to high;4) low. Serial hemolymph samples were col-lected every 4 days until oviposition, andthe maximum levels of VG (VGmax) and SPs(SPmax) for each individual (and age at whichthey occurred) were determined. We ob-served no effect on VGmax levels, but SPmax

levels in hoppers fed diets 3 and 4 were halfthat of hoppers fed diets 1 and 2. The timefrom eclosion to VGmax was significantlygreater in hoppers fed diets 3 and 4, whereasthe time from VGmax to oviposition was not.Similarly, time from eclosion to SPmax wassignificantly greater in hoppers fed diets 3and 4, whereas the time from SPmax to ovi-position was not. These data show that VGmax

and SPmax are physiological landmarks as-sociated with the canalized phase of oogen-esis in grasshoppers. We hypothesize thatfactors that inhibit the increase of VG and SPtiters may be involved in the initiation of ca-nalization. (Supported by NSF grant DB1-9978810 to DB & SJ.)

32.4 HAUSSMANN,M.F.*, VLECK,C.M.,BRENNER,S.A., Iowa State University,Ames. Aging animals using telomere length- a novel approach.

Field biologists often must work with ani-mals for which there is no prior history. A

physiological marker of an animal’s agewould offer insight into how age and experi-ence affect reproductive success and otherlife history parameters. The length of telom-eres, theprotective caps on the ends of chro-mosomes, has been shown to shorten withage in humans. Our objective was to deter-mine if telomere restriction fragmentscleaved from blood cell DNA would shortenas birds aged, thus providing a relativelynon-invasive way to estimate ages of ani-mals. We took blood samples from fourteenzebra finches placed in three age groups,juvenile (< 2 months old, n=5), young (12 to13 months old, n=5) and old (> 24 months,n=4). The DNA was extracted from isolatederythrocyte nuclei, digested, and separatedon a nondenaturing agarose gel. The gelwas dried and hybridized with 32P-labeled(C3TA2)4 oligonucleotides and telomere re-striction fragments were than visualized us-ing a phosphor screen. Mean telomerelength was determined using densitometry.Telomere length decreased with age in thezebra finches (ANOVA, F2,11 = 7.18, P = .01)Juvenile birds had longer telomere frag-ments than old birds (juvenile = 7190 ± 207bp, old = 6008 ± 232 bp; Tukey-Kramer HSD,P < .05). In young birds, telomere length(6675 ± 232) was intermediate to that of ju-veniles and adults. To our knowledge, this isthe first demonstration in a non-humanstudy, of a change in telomere length withage. It may be possible, in the field, to esti-mate ages of animals with nucleated eryth-rocytes once the relationship between te-lomere length and age has been determined.This would allow the incorporation of ageinto estimates of factors affecting life historyparameters in cases where previous histo-ries of animals in the population are un-known.

P3.12HAUSWALDT, J.S.*, GLENN, T.C.,University of South Carolina, Columbia,Savannah River Ecology Laboratory, Aiken,SC. Population genetic structure of the dia-mondback terrapin, Malaclemys terrapincentrata, using microsatellite DNA markers.

The Diamondback terrapin is the onlyspecies of turtle in North America that exclu-sively inhabits brackish waters. Seven sub-species occur in separate regions from Cape

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Cod to western Texas. At the beginning oflast century terrapin numbers were drasti-cally reduced because of exploitation for thesoup trade. Since commercial harvest be-came unprofitable in the 1920s, most popu-lations have recovered. However, terrapinsface new human threats: habitat destructionand fragmentation, pollution, motor boating,and traffic that kills nesting females. Inci-dental killing by crab trapping is consideredto be one of the major threats. Currently littleis known about the population genetic struc-ture and mating biology. According to mark-recapture data, terrapins have high site fi-delity, staying in the same tidal creeks formany years. We are initiating studies to as-sess the effective population size, breedingstructure, and impacts of human activitiesfor terrapin populations from coastal SouthCarolina and Georgia using microsatelliteDNA markers. Results on the isolation ofmicrosatellite markers and preliminary dataon the genetic population structure will bepresented.

50.2 HAYES, K.H.*, KARL, S.A., Universityof South Florida, Tampa. Evolution of theIcorona complexî within the genusMelongena (Gastropoda:Melongenidae):evidence from internal transcribed spacersand microsatellite data.

Gastropods are an exceptionallyspeciose and diverse group of marine in-vertebrates, having undergone numerousadaptive radiations during their long evolu-tionary history. This diversity combined withtheir conspicuousness in the marine envi-ronment make them ideal organisms for thestudy of evolution in marine invertebrates.Gastropods in the genus Melongena offer aparticularly intriguing opportunity to study theevolution of intertidal invertebrates. Pres-ently, despite the use of traditional morpho-logical analysis in conjunction with data fromthe current geographic distribution, system-atic relationships and the evolutionary his-tory of the ICorona Complexî remain unclear.Additonal techniques will be required to gaina better understanding of the evolution ofthis species complex. Using Ribosomal in-ternal transcribed spacer DNA sequencesand microsatellite allele frequencies we areaddressing some of the more difficult ques-

tions concerning the evolution within this ge-nus. These data will allow the interpretationof present-day distribution patterns, past andpresent population parameters and the re-lationships within the species complex. Theyalso can provide an understanding of theevents that have led to these patterns and aclearer assessment of speciation in thismarine invertebrate.

S9.3 HAYES, T. B., University of California,Berkeley. Evolutionary developmental en-docrinology and behaviorial ecology: an in-tegrative approach to understanding thestress response in western toads (Bufoboreas).

We showed that exogenous corticoster-one (CORT) decreased growth and devel-opment in early larval stages, but increaseddevelopment and stimulated metamorpho-sis during later stages in the western toad(Bufo boreas). Later, we showed that endog-enous CORT increased with larval density,while growth and development decreased.Furthermore, we recently showed that inhib-iting CORT-synthesis with metyrapone pre-vented the inhibition of growth and develop-ment associated with crowding. Thus, ourdata support a natural role for CORT in regu-lating the response to crowding in this spe-cies. Here, we propose an adaptive model,in which crowded larvae in a natural popu-lation may grow and develop slower in re-sponse to increased CORT during earlystages. On the contrary, older (or later-stagedlarvae) will accelerate development andmetamorphosis in response to crowding,thereby alleviating some of the crowdingstress. The adaptive significance of themodel is increased if Bufo boreas shows kinrecognition and preferentially schools withsiblings, as shown in the literature. Kin rec-ognition would increase inclusive fitness:Once older siblings metamorphose (allevi-ating crowding), then younger sibs wouldhave the opportunity to develop faster andmetamorphosis, as opposed to intense com-petition between all larvae. An examinationof mixed versus pure sib groups could notidentify a difference between these groupsin their response to crowding. Thus the pro-posed strategy can be realized only if tad-poles truly show kin recognition and/or if

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adults show philopatry such that schools ofmixed sibships are minimized. Supportedby NSF grants IBN-9513362 and IBN-9508996.

52.4 HAZARD, L.C.*, SHEMANSKI, D.R.,NAGY, K.A., University of California, Los An-geles. Digestibility of native and exotic foodplants eaten by juvenile desert tortoises.

Exotic plants can comprise a majorcomponent of the diet for some desert tor-toises (Gopherus agassizii) in the MojaveDesert. Introduced plants may not be asnutritious as native plants. Nutrient avail-ability in a native grass (Achnatherumhymenoides), an introduced grass(Schismus barbatus), a native forb(Malacothrix glabrata) and an introducedforb (Erodium cicutarium) were measuredin one to two year old juvenile desert tor-toises. We fed tortoises measuredamounts of chopped foods daily for ~130days (dry grass) or ~90 days (fresh orthawed forb). Orts and feces were col-lected daily and dried to constant mass,and energy, water, calcium, phosphorus,and nitrogen content of food and feceswere measured. Apparent dry matter andenergy digestibilities (percent of ingestedmaterial retained) were low for A.hymenoides and S. barbatus (dry matter42% and 45%; energy 39% and 45%, re-spectively), and did not differ significantlybetween grass species. Apparent drymatter digestibility was higher for M.glabrata (56%) and E. cicutarium (71%).Tortoises did not grow while feeding oneither grass; mass changes were prima-rily due to water imbalances. Tortoisesgrew on both forb diets. Voluntary intakerates were higher for the forbs than for thegrasses. Therefore, the higher growth ratesfor forbs were the result of both higher in-take rate and higher digestibility of thesefoods. Adult tortoises fed the same dietshad similar digestibilities as did the juve-nile tortoises. Dietary digestibility is betterexplained by the type of food (forb vs.grass) than by its geographic origin (na-tive vs. exotic).

22.5 HEDRICK, T.L.*, TOBALSKE, B.W.,BIEWENER, A.A., Harvard University, Uni-

versity of Portland, Harvard University 3Dkinematic analysis of lift production over arange of speeds in ring-necked doves andcockatiels.

A central problem limiting our understand-ing of the aerodynamics of avian flight is thelack of 3D kinematic data of wing motion.The lift generated by a wing is proportionalto 1) the square of incurrent air velocity (i.e.the velocity resulting from the bird’s forwardprogress and the motion of its wings), 2) thewingís angle of attack, and 3) wingspan, allof which may be altered by a bird with flex-ible, flapping wings moving along a 3D path.To help clarify which of these parametersbirds actually vary to fly at different speeds,we investigated 3D wing kinematics of cock-atiels (Nymphicus hallandicus) and ring-necked doves (Streptopelia risoria) as theyflew in a variable-speed wind tunnel atspeeds of 1 to 15 m/s. To reconstruct the 3Dcoordinates of points marked on the wingand body, we used a direct linear transfor-mation to merge the 2D views provided by4, synchronized, Redlake high-speed videocameras (250 Hz). During downstroke inboth species we found that angle of attackvaried fourfold over the range of speeds stud-ied, while incurrent air velocity varied by lessthan twofold and wingspan varied onlyslightly. Thus, flapping birds primarily ma-nipulate lift generation over a range ofspeeds by varying angle of attack and sec-ondarily by changing the downstroke veloc-ity of the wing. (Supported by NSF IBN-9923699)

P2.74HEITMANN, D.M.*, SCHEUNEMANN,T.L., CARELLO, C.A., University of Wiscon-sin-Eau Claire. The effect of surface gradeson the joint kinematics of quail during run-ning.

Locomotion is a major component to mostanimals’ daily energy budgets. Button Quail(Coturnix chinensis) are ground foragers andtherefore spend a predominant amount oftime walking and running. However, little isknown about how surface grades and run-ning speeds affect their stride parametersand joint kinematics. Stride parameters andjoint kinematics are useful tools for evaluat-ing how surface substrates affect the cost oflocomotion because they reveal the relative

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time and range of motion devoted to decel-eration and acceleration during each step.Deceleration occurs at the beginning of thestep from when the foot strikes the grounduntil the middle of the stance. During thistime potential energy can be stored in theelastic tendons and muscles. We quantifieddeceleration as the total amount of flexion ateach joint. On the other hand, accelerationoccurs at the end of the stance phase whenthe animal is pushing itself forward. This isthe energetically expensive phase of thestep. We quantified acceleration as the totalamount of extension at each joint. We useda high speed digital camera to film ButtonQuail running on a motorized treadmill on alevel surface, two inclines (10o and 20 o)and a decline (10 o). The Quail had markerson their lower limb joints for the purpose ofdigital analysis. We found that flexion at theankle and knee joints decreased with in-creasing incline and that extension of theankle, knee and hip joints increased withincreasing incline. These results suggest thatas animals run uphill there is an overall de-crease in the potential for storing elastic en-ergy in the tendons and muscles and thatmore energy must be devoted to the accel-eration phase of the step.

12.1 HELMUTH, B.*, HOFMANN, G.E.,University South Carolina, Arizona StateUniversity Defining thermal stress in the rockyintertidal: linking ecology and physiologythrough biophysics.

Thermal stress is thought to be an impor-tant determinant of organismal distribution,abundance, and productivity in the rocky in-tertidal zone. Yet, we know surprisingly littleof how body temperatures change in spaceand time, and of how these changes trans-late into physiological stress. We monitoredthe body temperatures of intertidal mussels(Mytilus californianus) at a site in centralCalifornia for a period of two years, at inter-vals of 5-10 minutes, on both horizontal andvertical, north-facing rock surfaces. Resultsshowed strong effects of substrate, and mus-sels on north-facing slopes were often morethan 10ƒ cooler than those on adjacent hori-zontal surfaces. Body temperatures wereonly very poorly correlated with air tempera-tures, and differed substantially from tem-

perature data recorded by adjacent loggers(Tidbits) placed directly on the rock surfaceor within mussel beds. We concurrentlymeasured levels of two molecular chaper-ones from the 70 kDa heat shock family(hsp70/hsc70) at intervals of 3-4 months.These proteins served as biochemical indi-cators of stress to the protein pool and pro-vided insight into protein homeostasis ineach population of mussels. The datashowed that mussels on horizontal surfaceshad higher levels of Hsps than those fromthe north-facing locations, indicating thatanimals on horizontal surfaces were morefrequently exposed to thermal conditions thatwould denature cellular proteins, disruptprotein homeostasis and thus, require morechaperone molecules to address the largepopulation of non native proteins. Our re-sults show that levels of thermal stress withinan intertidal site vary substantially in spaceand time, and that only through a combinedbiochemical and biophysical approach canwe understand patterns in thermal stress inthe rocky intertidal zone.

62.3 HENDERSON, S.Y., University ofWashington, Seattle. Adult nutrition on juve-nile growth in Bugula pacifica.

Bugula pacifica supplies nutrients to de-veloping brooded larvae through a pla-centa-like attachment. Previous experimentsof mine showed trends toward smaller lar-val size, slower growth, and longer time tofirst reproduction for juvenile colonies thatcame from nutritionally stressed adults whencompared to larval and juvenile controls. Laband field experiments performed in summer2000 tested the influence of the adult envi-ronment on the success of developing lar-vae using a factorial design with two nutri-tional treatments (high and low). In the lowfood treatment colonies were maintained atambient food levels, and in the high foodtreatment colonies received supplementalfood twice daily. After two weeks, larvae col-lected from each adult treatment were al-lowed to metamorphose and placed in highand low food environments to examine theeffect of adult nutrition on a suite of post-metamorphic characters. Juvenile colonieswere observed for 26 days after larval settle-ment. Results suggest that the adult envi-

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ronment did not affect juvenile growth ratein high food conditions, but in low food con-ditions, juveniles from nutritionally stressedadults have slower growth and higher mor-tality. To examine the effect of adult nutritionon survival and growth under field condi-tions, newly settled larvae from the two adulttreatments were allowed to grow on settle-ment plates and were transplanted after 3days to the laboratory docks. Juvenile colo-nies were observed for 26 days after larvalsettlement. In the absence of competition,results indicate that juveniles from nutrition-ally stressed adults grow just as well as ju-veniles from fed adults.

S15.5HENEN, B.T., University of California,Los Angeles; Smithsonian. Reproductiveeffort and reproductive nutrition of femaledesert tortoises: essential field methods.

The reproductive output of female deserttortoises (Gopherus agassizii) may appearindependent of rainfall and the springtimeabundance of their preferred food, annualplants. To evaluate whether body reserves(energy, water and other nutrients) influencereproductive success and its apparent inde-pendence from such rainfall and food, threeinnovative, essential field methods (i.e., cy-clopropane, doubly-labeled water and ra-diographic methods) were used to measureindividual energy and water budgets of wild,female desert tortoises for two reproductivecycles (years). Body energy and water re-serves, field metabolic rates, and water fluxrates changed significantly amongst sea-sons and years, reflecting the females’ op-portunistic and copious storage of energyand water for subsequent support of metabo-lism and egg production when food and rain-water were scarce. Through a 90% reduc-tion of metabolic rates, females conservedenough body reserves to produce eggs dur-ing extreme drought conditions, an effectivebet-hedging reproductive pattern for animalsinhabiting an extreme and unpredictable en-vironment. Ultrasonographic analyses onwild and captive female tortoises are reveal-ing how reproductive cycles enable, andsometimes limit, egg production. Finally,studies of reproductive nutrition are reveal-ing the importance of nitrogen, and perhapsother nutrients, to female reproductive suc-

cess. New technology and field methodsare furthering basic science and conserva-tion efforts.

P1.68HENRY, M., University of South Caro-lina, Columbia. Modeling body temperatureof intertidal snails: hot mud and hot bodies.

Intertidal snails face a cyclical ambientenvironmental regime due in part to the tides.However, do their body temperatureschange along with the ambient environmentor do they act as biological filters, not beingaffected by factors like the drastic tempera-ture change around them? In a preliminarystudy conducted in the Pacific Northwest,environmental parameters of solar radiation,ground temperature, air temperature, rela-tive humidity, and wind speed, were exam-ined to determine their effects on the bodytemperature of snail models (empty shellsfilled with modeling clay). Data on the envi-ronmental parameters were collected dur-ing two days, at approximately the same timeof the tidal cycle, and used as tests of a math-ematical model of heat flux. the thermal en-ergy model included only conductoin, con-vection, IR radiation, and short-wave solarradiation terms. The mathematical modelestimated body temperatures within 1.5 de-grees of actual body temperatures recordedin the field. Estimated body temperatureswere within 0.5 degree of the ground tem-peratures, suggesting that the conductionterm plays a large role in determining inter-nal temperature of snails in rocky intertidalhabitats. The ability to predict and explainthe internal body temperature of intertidalorganisms can be an aid in explaining popu-lation distribution, migration patterns, andoperating temperature ranges.

P1.51HENRY, R.P., Auburn University. Sup-pression of salinity-sensitive branchial car-bonic anhydrase induction by a compoundin the eyestalk of the euryhaline green crab,Carcinus maenas.

Carbonic anhydrase activity in the pos-terior gills of the euryhaline green crab,Carcinus maenas, undergoes an 8 fold in-duction upon transfer from 32 to 12 ppt sa-linity. Eyestalk ablation (ESA) results in a50% increase in CA activity even in the ab-sence of a salinity change, and a 20% in-

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crease in activity after salinity transfer. Crabswere treated with ESA and subsequently in-jected daily for 7 days with supernatant ofcrude eyestalk homogenate, the equivalentof two eyestalks per day. Crabs acclimatedto 32 ppt, treated with ESA and injections,had no increase in CA activity; values weresimilar to control animals injected with seawater. Injection of eyestalk extract also sup-pressed CA induction in crabs treated withESA and low salinity exposure. CA activityin the posterior gills was significantly lowerthan in uninjected animals. Furthermore,injection of eyestalk extract suppressed CAinduction by 50% in intact crabs (no ESAtreatment) exposed to low salinity. Theseresults point to the presence of a substancein the eyestalk that functions to suppress CAexpression at high salinity. Suppression isremoved upon exposure to low salinity, andtreatment with ESA enhances that effect.Adding back the substance through injec-tion of eyestalk extract not only reverses theeffects of ESA, but it also prevents the nor-mal low salinity-mediated induction of CA inintact crabs. Supported by NSF IBN 97-27835.

51.2 HERBERHOLZ, J., ISSA, F.A.,EDWARDS, D.H., Georgia State University.The role of tailflip behavior in crayfish dur-ing dominance hierarchy formation.

When placed together in a limited space,crayfish engage in agonistic interactions thatlead to formation of social dominance hier-archies. The interactions feature attacks,where one animal physically assaults an-other with its claws, approaches, where nocontact occurs, retreats, where one animalwalks away from another, and escapes,where rapid tail flexions and extensionsthrust the animal away from the opponent.Escapes are triggered by activation of threediscrete neural circuits in crayfish, two ofwhich depend on giant command neurons.To determine how these different escapecircuits were used during dominance hier-archy formation, we placed a pair of elec-trodes in the aquarium with the animals torecord electric field potentials produced bythe giant neurons, the motor neurons andthe muscle. Activation of each tailflip circuit

could be determined from differences in thefield potentials that they produce. We usedthis non-interfering method to record activa-tion of the circuits in pairs of previously un-acquainted animals placed together in afreshwater aquarium. We found that duringinitial fighting, both animals performed at-tacks, approaches, and a new agonistic be-havior, offensive tailflips. This behavior isperformed by one animal as it grapples an-other; the offensive tailflips thrust the animalabove its opponent which is dragged about.Quite suddenly, usually after a bout of offen-sive tailflipping by one animal, the other willinitiate a series of escape tailflips mediatedeither by the medial giant neurons or by thenon-giant neurons. This is the decision pointfor social hierarchy formation, after which thebehavior of the dominant and subordinateanimals diverge.

S9.6 HERMAN, J.P.*, ZIEGLER, D.R.,CULLINAN, W.E., University of Cincinnati,University of Cincinnati, Marquette Univer-sity. Neurocircuit regulation of thehypothalamo-pituitary-adrenocortical axis.

Regulation of the hypothalamo-pitu-itary-adrenocortical (HPA) axis is coordi-nated by an elaborate neurocircuitry con-trolling activation of parvocellular neuro-secretory neurons resident in the hypo-thalamic paraventricular nucleus (PVN).Recent studies in our laboratory suggestthat neurocircuits controlling HPA axis ac-tivity are stressor-specific: rapid responsesto physical challenge (systemic stressors)primarily traverse brainstem circuitry,whereas responses to brain-assembled(processive) stressors involve multi-syn-aptic connections between the limbic sys-tem and PVN. Our recent work indicatesthat limbic control of HPA activity involvesa diffuse innervation to collections of PVN-projecting cell groups in the basal fore-brain and hypothalamus, particularly inthe perinuclear zone of the nucleus itself.In all, control of HPA responses to brain-built stressors appears to require commu-nication with hypothalamic regions con-trolling homeostasis, allowing the brain tobe advised of ongoing physiological sta-tus prior to initiating stress responses to

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psychological stimuli. Supported byMH49698, AG12962, IBN9814400 andMH60819.

S6.6 HERNANDEZ, L.P., Wesleyan Univer-sity, Middletown, CT. Functional morphologyand developmental biology of zebrafish: re-ciprocal illumination from an unlikely couple.

Developmental biology and functionalmorphology have not generally been con-sidered fields across which a useful synergycould evolve. However, recent discoveriesin vertebrate morphology have been due toadoption of techniques commonly used bydevelopmental biologists. Furthermore, re-ciprocal contributions are beginning toemerge. Functional morphology is now help-ing to explain unique patterns of morpho-genesis during early embryonic stages. Asbroadly defined here, developmental biol-ogy encompasses the functional aspects ofearly life history stages as well as molecularprocesses involved in embryonic pattern for-mation. I will first discuss the insights gainedfrom research examining the biomechanicsand kinematics of larval fish feeding in rela-tion to established paradigms based onadults. Functional morphologists have longexamined adult feeding mechanics, but havelargely ignored feeding mechanics at larvalstages. Larval zebrafish were shown to havesignificantly different kinematic profiles fromadults due to both constructional constraintsand Reynolds number regime. I will thenaddress how functional studies of larval be-havior are the basis for hypotheses that canbe tested using the methodologies of thedevelopmental biologist. Such functionaldata on larval performance are significant inidentifying anatomical complexes that mustundergo seamless embryogenesis to assurelarval survival. For example, the emphasison pronounced head lift and extreme hyoiddepression during feeding in larval zebrafishhas important implications for the develop-mental pathways leading to the formation ofstructures associated with these movementsduring early development.

S3.6 HERREL, A.*, MEYERS, J.J.,NISHIKAWA, K.C., DE VREE, F., Universityof Antwerp, Belgium, Northern Arizona Uni-versity, Flagstaff, Northern Arizona Univer-

sity, Flagstaff, University of Antwerp, Belgium.The evolution of feeding motor patterns inlizards: modulatory complexity and con-straints.

Previous research indicated that the evo-lution of feeding motor patterns across ma-jor taxonomic groups might have occurredwithout large modifications of the control ofthe jaw and hyolingual muscles. However,the proposal of this evolutionary scheme washampered by the lack of data for some keytaxa such as lizards. Recent data on jawand hyolingual feeding motor patterns of anumber of lizard families suggest extensivevariability within and between species. Al-though most lizards respond to changes inthe structural properties of food items bymodulating the activation of the jaw andhyolingual muscles, some food specialistsmight have lost this ability. Whereas the over-all similarity in motor patterns across differ-ent lineages of lizards is large for thehyolingual muscles, jaw muscle activationpatterns seem to be more flexible. Never-theless, all data suggest that both the jawand hyolingual system are complexly inte-grated. The elimination of feedback path-ways from the hyolingual system throughnerve transection experiments clearly showsthat feedings cycles are largely shaped byfeedback interactions. Yet, novel motor pat-terns including unilateral control seem tohave emerged in the evolution from lizardsto snakes.

64.2 HEYLAND, A.*, HODIN, J., Depart-ment of Zoology, University of Florida, Gaine,Seattle Central Community College, Seattle,WA, USA. Endogenous thyroxine productionin sand dollar larvae and its implication forthe evolutionary loss of larval feeding.

Studies on thyroid hormone [T3 and thy-roxine (T4)] effects on metamorphosis inamphibians have begun to elucidate howchanges in thyroid hormone productionand cellular responses underlie alter-ations in life history patterns. Recently,work on several echinoderm species hasdemonstrated that thyroxine acceleratesmetamorphosis in this group as well. In-terestingly, the feeding larvae of severalspecies of sea urchins seem to obtain thy-roxine through their diet of planktonic al-

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gae, while non-feeding larvae of the sanddollar Peronella Japonica endogenouslyproduce thyroxine. In order to understandthe role of thyroxine production in the evo-lutionary shift from feeding (planktotrophic)to non-feeding (lecithotrophic) larval de-velopment, endogenous thyroid hormoneproduction in feeding larva has to be in-vestigated more broadly in echinoderms.Here we examine the effects of thyroxineand a thyroxine synthesis inhibitor on thedevelopment of Dendraster excentricus,a sand dollar with a feeding larva. Thyrox-ine synthesis inhibitor treatments indicatethat Dendraster excentricus larvae endog-enously produce thyroxine in addition tothe exogenous thyroxine source. More-over, time to metamorphosis and juvenilesize were significantly reduced in the thy-roxine treatments, which emphasizes theimportant role of thyroxine in the develop-ment of this species. We also report thatskeleton length was reduced and vestibuleinvagination progressed faster in the thy-roxine treatments when compared to con-trols. Endogenous TH production might bea shared feature among sand dollars,which facil itates the evolution oflecithotrophy. Mounting evidence on theeffects of thyroxine in echinoderm devel-opment suggests life history models needto incorporate the evolution of thyroxineproduction.

57.2 HIEBERT, S.M.*, SALVANTE, K.,RAMENOFSKY, M., WINGFIELD, J.C.,Swarthmore College, University of Washing-ton, University of Washington, University ofWashington. Seasonal differences in the re-sponse of corticosterone and nocturnal tor-por to energy challenge in rufous humming-birds.

The energy balance of captive rufoushummingbirds (Selasphorus rufus) was chal-lenged during the autumn migratory sea-son and during the late winter prebasic moltby diluting the artificial nectar on which thebirds feed. Body mass, cloacal fluid corti-costerone, and duration of nocturnal torporwere then compared between food dilutionand normal food treatments, and betweenmigratory and molting birds. Differences be-

tween migratory and molting birds in the re-sponse patterns of all three variables to thesame food dilution treatments demonstratethat corticosterone concentrations alone arenot sufficient to explain the differences intorpor use in migratory and molting birds,and argue against an earlier hypothesis thatcorticosterone could serve as the ultimateintegrator of information about physiologi-cal condition and environmental energyavailability to the torpor regulation system.Additional experiments demonstrated thatthe sensitivity of torpor to exogenous corti-costerone during late summer differs be-tween the sexes in parallel with differencesin the timing of southward migration by adultmales and females. Although duration ofnocturnal torpor was influenced by adminis-tration of exogenous corticosterone in sev-eral experiments, the results do not distin-guish between a direct influence of corticos-terone on torpor, and an indirect influence ofcorticosterone on torpor through other vari-ables such as food consumption and bodymass.

37.4 HIGGINS, C.L., BUTLER, P.J.,STRAUSS, R.E.*, Texas Tech University, Lub-bock. Discrimination of foraging paths pro-duced by different search models.

The analysis of search paths plays a keyrole in optimal foraging theory. We devel-oped a simplified model of resource acqui-sition in which we randomly dispersed Npoints (“food items”) of equal value withinan arena, and considered only the searchpath followed to find and consume the Nitems (assuming no satiation or learning) bycomputer simulation. For a given point con-figuration, two deterministic models, the glo-bally optimal shortest and longest paths, pro-vide the lower and upper bounds on pathlength. We characterized the lengths andshapes of search paths produced under fiveprobabilistic and two other deterministicmodels: random choice, Pearson randomwalk, Levy random walk, reciprocal-distancepreference, inverse-squared-distance pref-erence, trajectory-directed search, and near-est neighbor. Each resulting search pathwas characterized geometrically by its totallength, distribution of step lengths, vector

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autocorrelation function, distribution of an-gular deviations, and number and spacingof path intersections. We used linear dis-criminant analysis and nonlinear multilayerperceptrons (artificial neural networks) todiscriminate paths produced by the differentmodels based on these path descriptors.This basic procedure can be extended invarious ways and can potentially be used toclassify observed search patterns of forag-ers according to underlying behavioral mod-els. The results suggest that organisms canattain near-optimal performance using bio-logically realistic search tactics.

S7.2 HIGGINS, R.P.*, NEUHAUS, B., Uni-versity of North Carolina, Asheville, HumboltUniversity, Berlin. Kinorhyncha.

The Kinorhyncha are protostome, bilat-erally symmetrical, exclusively free-livingmarine animals, less than 1 mm long, andecologically part of the meiofauna, eitherendo- or mesobenthic, and euryhadyl. Theyoccur throughout the world, generally insedimients but sometimes associated withplants or other animals. Kinorhynchs aresegmented as evidenced by their nervoussystem, the muscular system, a system ofsubcuticular glands, sequential rings ofscalids on the head and variously dividedcuticular rings on the neck and trunk, all to-gether forming 13 segments. Significant in-formation has been accumulated aboutpost-embryonic development but nothing isknown about kinorhynch embryology. Theirbody cavity is a sac filled with amoebocytes.the excretory system consists of a single pairof protonephridia lying dorsolateral to thegut in segments 10 and 11. About 150 spe-cies have been described and comprise 14genera, 8 families and 2 orders. Their rela-tionship to other phyla will be discussed.

21.5 HIGHAM, T.E.*, DAVENPORT, M.,MATTINGLY, W.B., JAYNE, B.C., Universityof Cincinnati. Effects of turning angle onsprinting performance of three ecomorphsof arboreal lizards.

Most studies on the locomotion of ani-mals are for straight, steady speed move-ments; however, many species often performmaneuvering or intermittent locomotion intheir natural habitats. Lizards, including sev-

eral arboreal species, have been commonmodels for testing locomotor performance.However, no previous study has determinedhow maneuvering on arboreal perches mayaffect locomotor performance of lizards.Thus, for three sympatric species of arbo-real lizards (Anolis lineatopus, A. grahami,and A. valencienni) that are differentecomorphs with different sprinting abilities,we determined how the angle of turning af-fected locomotor performance. We usedhigh-speed video (250 images/sec) torecord the maximal running speeds of thelizards on a two-meter racetrack made of4.8 cm diameter pipes covered with fiber-glass mesh and inclined 30ƒ. We used race-tracks that were straight or had turn anglesof 30ƒ or 90ƒ at the midpoint of the track,and we quantified the elapsed time andspeeds of lizard locomotion for the middle30-cm of the track. The total elapsed time totravel 30 cm increased significantly with in-creased turn angle for all three species, butthe magnitude of the increase in elapsedtime varied among species. Pauses in loco-motion became significantly more frequentand longer as turn angle increased, and thetwig anole, A. valencienni, paused more thanthe other two species. As turn angle in-creased, turning by jumping (rather than run-ning on the perch) occurred more frequentlyfor all species. Supported by NSF IBN 99-83003.

P3.20HILL, A.L.*, HILL, M.S, LIUBICICH,D.M., Fairfield University. Insights into earlyanimal evolution: developmental genes insponges.

HOM/Hox genes play vital roles in ani-mal development, and a number of re-searchers have hypothesized that a primor-dial-Hox gene or a cluster of two or moregenes must exist in sponge genomes. APCR-based strategy using degenerate oli-gonucleotide primers was employed to iden-tify important homeobox genes (includingHOM/Hox) in marine and freshwatersponges. Several potential HOM/Hox se-quences, as well as a Pax gene and anHMG-box gene, have been identified inmarine and freshwater sponge species. Us-ing RT-PCR and Northern blot analysis, wehave also begun characterizing temporal

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expression patterns of these genes in free-swimming larvae, recently settled larvae,and young adult sponges. Furthermore, pre-liminary in situ hybridization experimentshave been performed to elucidate spatialexpression patterns. Porifera represent themost basal radiation of all extant phyla fromthe metazoan lineage, and given metazoanmonophyly, it is clear that all animal bodyplans must have arisen from transformationsof a single body plan. Sponges may holdimportant clues to the ancestral state(s) ofmany genetically controlled developmentalprograms in the animal kingdom.

S1.1 HILL, P.S.M., University of Tulsa, OK.Vibration and animal communication: a re-view.

Vibration through the substrate has likelybeen important to animals as a channel ofcommunication for millions of years, but ourliterature on vibration in this context of bio-logically relevant information is a feature ofessentially the last 30 years. Morphologistsknow that the jaw mechanism of early am-phibians allowed them to perceive vibrationthrough the substrate as their large headslay on the ground. Although the exact mecha-nism of vibration production and the precisenature of the wave produced are not alwaysunderstood, recent development of afford-able instrumentation to detect and measurevibrations has allowed researchers to an-swer increasingly sophisticated questionsabout how animals send and receive sig-nals through this medium. We have knownfor some time that leafcutter ants use vibra-tion to recruit foragers, or to signal for helpwhen buried alive, but the study of vibrationin animal communication is still a relativelyyoung field. Some of us were forced to ex-plore the use of vibration when all other at-tempts to manipulate animals in the field hadfailed. Others began to think about vibrationto explain some of the puzzling behaviors ofspecies they were studying in other contexts.Since then, it has become clear that the useof vibration in animal communication is muchmore ubiquitous than previously imagined.We now know that vibration provides infor-mation used in predator defense, prey de-tection, recruitment to food, mate choice,

intrasexual competition, and maternal/broodsocial interactions in a variety of insect or-ders, spiders, crabs, scorpions, chameleons,frogs, golden moles, mole rats, kangaroorats, elephants and bison.

6.3 HILTON, E.J., University of Massachu-setts Amherst. Morphological complexity andsimplicity of the axial skeleton of Teleostei.

Morphological complexity is a difficult andrelative term, generally equated with agreater number of parts or the elaboration ofa basic structural element. The vertebral skel-eton of Teleostei is among the most complexof all vertebrates, with up to thirteen discreteossifications per body segment (more insome taxa). In this study, I examined fusionamong the pre-ural vertebral elements in abroad survey of taxa. In ∂Ichthyodectiformescentra are spool-shaped elements fromwhich the neural and haemal arches andparapophyses remain separate. InElopiformes, the haemal arches and caudalneural arches are fused to the centra; theabdominal neural arches remain autog-enous and the parapophyses are only par-tially, if at all, fused to the centra. In basalOsteoglossomorpha all elements except theabdominal neural arches are fused to thecentra; in more derived osteoglossomorphsthe abdominal neural arches are fused tothe centra. In Clupeomorpha, the anteriorneural arches and parapophyses remain au-togenous. In Cypriniformes, the very ante-rior neural arches and most of theparapophyses are autogenous, although theanterior vertebral column is greatly elabo-rated in association with the Weberian ap-paratus. In more derived teleosts, each ver-tebra is fused into a single unit - in essence,simplified. With this simplification, however,there is often considerable elaboration(=complexity) of a sort not seen in morebasal teleosts. For example, many groups ofPercomorpha have independently evolvedwell-developed zygopophyses and othermodifications of the vertebral elements.

S10.2HIRSCH, A.M., UCLA. What are theconserved elements in symbiotic associa-tions between plants and microbes?

The nitrogen-fixing symbiosis betweenRhizobiaceae and legumes is one of the

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best-studied interactions established be-tween prokaryotes and eukaryotes.Dinitrogen is fixed into ammonia by rhizobiaand made available to theplant in exchangefor carbon. The plant also develops root nod-ules that house the bacteria. It has beenhypothesized that this symbiosis evolvedfrom the more ancient vesicular-arbuscularmycorrhizal symbiosis. Support comes fromlegume mutants where Nod- and Myc- co-segregate. We also found that two earlynodulin (ENOD) genes, ENOD40 andENOD2, are expressed in alfalfa VA-mycor-rhizae, supporting the idea that the signaltransduction pathways between the twosymbioses are conserved. Now, we haveanalyzed the responses of 5 classes of non-nodulating Melilotus alba (whitesweetclover) mutants to both Sinorhizobiummeliloti (the nitrogen-fixing symbiont) andGlomus intraradices (the mycorrhizal sym-biont) to investigate how Nod- mutations af-fect the establishment of each symbiosis andthe induction of downstream genes. Of thedifferent classes, only the Sym3 mutant isboth Nod- and Myc-. In addition, we foundno up-regulation of ENOD40 gene expres-sion in response to inoculation with eithersymbiont. Other responses downstream ofthe initial perception of the symbiont are alsonot activated compared to those of wild-typeplants indicating that Sym3 is blocked in avery early stage of the interaction. More-over, there appears to be no elicitation of adefense response indicating that the host,whether wild type or mutant, recognizes themicrobe as a “friend” and not as a “foe” evenif the interaction is ultimately ineffectual.These data and their implications to sym-biosis overall will be discussed.

P1.88HOAGLAND, T.M.*, ROESER, M.,OLSON, K.R., University of Notre Dame, IN*,University of Notre Dame, IN, Indiana Uni-versity Sch. of Medicine. Venous function introut.

The venous system is an important effec-tor of cardiovascular homeostasis in mam-mals, whereas this vasculatureís function infish, remains nebulous. Fish live in a gravity-free environment and their veins appearpoorly endowed with smooth muscle, there-

fore it has been suggested that fish veinsserve primarily as passive conduits for thereturn of blood to the heart. In the presentstudy, venous function was examined inunanesthetized rainbow trout in vivo,through the construction of vascular capaci-tance curves. Vascular compliance and un-stressed blood volume can be determinedfrom these curves and they are key indexesfor describing venous function. Through theuse of pharmacological probing via auto-nomic nervous system blockers in both freshand salt water adapted fish, it appears clearthat venous regulation takes place. Further-more, this active regulation of venous ca-pacitance lends evidence to support a rolein cardiovascular homeostatic control by thevenous vasculature, in trout.

55.5 HOAGLAND, T.M.*, HANCOCK, T.V.,HILLMAN, S.S., University of Notre Dame,IN, University of Colorado, Boulder, PortlandState University, OR. Systemic vascular com-pliance in two amphibians.

The mean circulatory filling pressure(MCFP), vascular compliance (VC) and un-stressed blood volume (USBV) were mea-sured in Bufo marinus and Ranacatesbeiana, using in vivo methods. Thesevalues are integral for the understanding ofvenous function and cardiovascular homeo-stasis, and have been determined in mam-mals and fish but never in amphibians. Inthe present experiments, systemic arch ar-terial (PSA) and ventral abdominal venous(PVEN) pressures were measured in unanes-thetized amphibians before and during me-chanical occlusion of the conus arteriosus,while total blood volume was incrementallymanipulated. Mechanical occlusion of theconus arteriosus (zero-flow condition) rap-idly (<10 s) dropped PSA and increased PVEN

(equals MCFP). Capacitance curves wereconstructed by varying total vascular volumeand then measuring MCFP during zero-flowcardiac output conditions. These capacitancecurves enable the extrapolation of the USBVand determination of VC. The MCFP, VC andUSBV were 8.6 ± 0.3 mmHg, 6.4 ± 0.4ml.mmHg-1.kg-1, 18.0 ml.kg-1 (24.3% of totalvascular volume) and 9.3 ± 0.3 mmHg, 3.8 ±0.3 ml.mmHg-1.kg-1 and 17.2 ml.kg-1 (31.1%

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of total vascular volume) for B. marinus andR. catesbeiana, respectively. These resultsshow that important measures of venousfunction are readily obtained in amphibiansand the more terrestrial cane toad has agreater VC and lower USBV than the aquaticfrog; these adaptations could be advanta-geous in the move to terrestriality.

50.1 HOCHBERG, R., University of NewHampshire, Durham. Function and system-atic distribution of helicoidal muscles inGastrotricha.

Studies on the muscular system of gas-trotrichs revealed the presence of musclesin a new orientation, that of left- and right-handed helices around the digestive tract.These helicoidal muscles are found on thepharynx and intestine of numerous speciesin both orders, Chaetonotida andMacrodasyida. In many cases, the helicessurround both circular and longitudinalmuscle bands. The number of helices is afunction of ontogeny, and their position alongthe alimentary canal may be family-specific.To date, helicoidal muscles have been foundin the following families: Chaetonotidae,Dactylopodolidae, Macrodasyidae,Thaumastodermatidae, Turbanellidae, andXenotrichulidae. The precise function ofthese muscles remains to be determined,but we hypothesize that they play two roles:antagonize dilations of the pharynx and in-testine during feeding and contribute toshape change in the body during ciliary lo-comotion. Based on their wide systematicdistribution, these muscles are likely to bepart of the ground pattern of the Gastrotricha.

P3.34HOCHBERG, R.*, LITVAITIS, M. K.,University of New Hampshire, Durham. Thenervous and muscular system ofDactylopodola baltica from a phylogeneticperspective.

Attempts to infer gastrotrich phylogenyfrom morphological characters has re-vealed the family Dactylopodolidae to bethe sister taxon to the rest of theMacrodasyida. Dactylopodola retains sev-eral plesiomorphic characteristics makingthe genus worthy of attention for furtherphylogenetic investigation. Here we reportthe results of research on two organ sys-

tems of D. baltica, the muscular and ner-vous system. Immunofluorescent localiza-tion of acetylated tubulin and serotonin re-vealed the orientation of both main nervecords and small sensory fibers in the spe-cies. In several cases, the nerves of D.baltica correspond in position to those ofother macrodasyid taxa. Unique to D.baltica is the innervation of immunoreac-tive 5-HT neurons in the cerebral eyes-pots. In the muscular system, the arrange-ment of specific muscle sets is similar be-tween D. baltica and other macrodasyidans:inner circular muscles, left- and right-handed helicoidal muscles, longitudinalmuscles, and outer circular rings. The ven-trolateral longitudinal muscles areuniquely arranged at the anterior and pos-terior portion of the body, as are their sitesof insertion. It is proposed that the struc-ture and orientation of the muscles andnerves reflect both local adaptation andphylogeny, and should provide a usefulsource for information on gastrotrich evo-lution.

38.1 HOESE, W.J.*, MOONEY, R.,NOWICKI, S., California State University,Fullerton, Duke University, Durham, NC,Duke University, Durham, NC. Neural en-coding of multiple song types in the swampsparrow HVc.

Many songbirds, including swamp spar-rows (Melospiza georgiana), sing multiplesong types as adults. In Songbirds that singonly a single song type, such as zebrafinches and white-crowned sparrows, neu-rons in the song nucleus HVc are song-se-lective, firing more strongly to forward thanreverse playback of the bird’s own song(BOS), and little or not at all to other conspe-cific songs. The manner in which a swampsparrow’s multiple song types are repre-sented by its auditory HVc neurons is un-known, but could help further our under-standing of the genesis and function of thesehighly selective neurons in song learningand perception. One idea is that all songtypes are equally effective at driving audi-tory responses in HVc neurons. A secondpossibility is that HVc neurons form a mo-saic, with certain cells firing preferentially inresponse to playback of one song or an-

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other. We addressed this issue by making invivo intracellular recordings from identifiedHVc neurons in urethane-anesthetizedadult male swamp sparrows, using auditoryplayback to present the individual’s differentsong types. We found that multiple songtypes were encoded in HVc in a song andcell type-specific manner, and that there weremarked differences in subthreshold versusfiring rate responses. Almost all neuronsfired more strongly (and often exclusively)to a single song and, within single birds, dif-ferent neurons could prefer different songs.In contrast, inhibitory and/or excitatory sub-threshold responses could be evoked byeach of the bird’s song types, but these morebroadly tuned subthreshold responses werestill selective for forward over reverse play-back. These results suggest a local hierar-chy within HVc, where broadly selective in-puts are refined to generate highly selec-tive, song-type specific firing in certain neu-rons.

P1.73HOFER, S.C.*, DRACKETT, M.,WATTS, S.A., University of Alabama, Bir-mingham, Calera High School, Alabama,University of Alabama,Birmingham. Low tem-perature tolerance of GMTtm tilapia,Oreochromis niloticus.

Genetically male tilapia (GMTTM) are pro-duced by crossing XX female and YY malebroodstock. They exhibit hybrid vigor withincreased growth rates and are favored foraquaculture in warm climates. In the US tila-pia fingerlings are cultured at hatcheries andare reared at 28 to 30 C. In southern regionsfingerlings can be transferred to outdoorponds for growout in the spring. Tempera-ture tolerance dictates the duration of thevaluable outdoor growing season. We ex-amined the low temperature tolerance limitby exposing GMTTM fingerlings acutely to lowtemperatures. Fingerlings (ca. 5 g) werereared at 28 C for several weeks and ex-posed (n = 90) to reduced temperatures for24 hr and then placed back into 28 C waterfor 72 hr. Survivorship was recorded afterthe initial exposure (24 hr) and at 24, 48,and 72 hr post-exposure. Greater than 98%of the fingerlings survived the initial expo-sure to 20 C and 18 C and the subsequent

recovery period. Fish exposed to 16 C ex-hibited a 97% survival rate after the initialexposure and a 90% survival rate after the24 hr recovery period. Fish exposed to 14 Cexhibited an 88% survival rate after the ini-tial exposure and a 76% survival rate afterthe 24 hr recovery period. No fish survivedexposure to 12 C. The significant differencein survivorship between the fish exposed to14 C and 12 C suggests an LT50 of approxi-mately 13 C. To maximize production we sug-gest that fingerlings be transferred to pondswith temperatures no lower than 18 C priorto the summer growing season.

P3.7 HOFFART, C.*, HILL, P.S.M., Univer-sity of Tulsa, OK. Morphological and molecu-lar phylogenetic analyses of theGryllotalpidae: what came first, the chirp orthe trill?

The prairie mole cricket (Gryllotalpa ma-jor) is a burrowing insect native to thetallgrass prairies of the southern UnitedStates. The male produces a loud, long-range calling song at sunset in April andMay by rubbing the plectrum of one wingalong the file of the other wing. The soundproduced is a series of chirps. The wingmorphology of G. major was compared withfive other mole cricket species found in NorthAmerica: N. hexadactyla, G. gryllotalpa, S.abbreviatus, S. vicinus, S. borellii. The over-all wing structures among the crickets weresimilar, yet calling songs differ in that G. ma-jor and N. hexadactyla chirp while the oth-ers trill. S. abbreviatus does not have a call-ing song. The type of calling song may re-flect an adaptation that promotes being heardin a particular habitat and may influence thetype of mating system of a species. In addi-tion, DNA sequence data were comparedfor the same species. A morphological phy-logeny and a molecular phylogeny for theGryllotalpidae were constructed to deter-mine if the different species express a simi-lar trait because they inherited it from a com-mon ancestor or because they acquired itindependently. The phylogenies account forthe history of character change and allowfor hypotheses to be developed regardingthe course of the mole crickets’ evolution andthe correlation of this with behavior traits.

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8.2 HOGUE, A.S.*, RAVOSA, M.J., North-western University Medical School, Chi-cago, IL. Mandibular symphyseal fusion inmammals: a test of competing hypotheses.

The mammalian lineage is replete withinstances of convergent acquisition of man-dibular symphyseal fusion. While a varietyof models have been proposed to explainthis phenomenon, three are currently de-bated in the literature. Two of these, the dor-soventral (DV) shear and wishboning mod-els, suggest that fusion functions to strengthenthe symphysis against DV shear of the sym-physis and lateral transverse bending of themandible, respectively. A third model, re-ferred to here as the transverse stiffnessmodel, argues that fusion serves to stiffenthe symphysis to facilitate transverse oc-clusal movements. ANCOVA and a nonpara-metric ANOVA were used to test mandibularscaling and occlusal orientation predictionsfrom each of these models in a sample of 44species of selenodont artiodactyls. Consis-tent with the wishboning and transverse stiff-ness models, taxa with fused symphyses(camelids) have more horizontally orientedM2 and M2 occlusal wear facets and ex-panded corpus and symphysis dimensionsin the horizontal plane (p<0.05). Contrary tothe DV shear model, camelids do not haverelatively deeper corpora to resist greaterparasagittal bending of the balancing-sidecorpus. While taxa with ossified symphyseshave relatively larger symphysis cross-sec-tional areas (consistent with the DV shearmodel), this appears to be the byproduct ofan increase in AP symphysis length whichserves to counter increased lateral trans-verse bending of the mandible. A consider-ation of the biomechanics of mastication fur-ther suggests that strength, not stiffness, isthe critical factor necessitating symphysealossification. These results provide additionalevidence that fusion and transverse masti-catory loads are functionally linked, furthersecuring the role of wishboning as the pri-mary determinant of symphyseal fusion inmammals.

P3.98HOLBERTON, R.L.*, WILSON, C.M.,HUNTER, M.J., LEE, A.W., University ofMaine, University of Mississippi, Universityof Mississippi, University of Mississippi. An

endocrine basis of different migratory strat-egies in long- and short-distance neotropicalmigrants.

Migratory birds show great variation inbehavioral and physiological strategies forreaching their destinations. We are com-paring behavior and physiology in two spe-cies of Neotropical migrants, the long-dis-tance migrant, the Blackpoll warbler(Dendroica striata) and the short-distancemigrant, the Yellow-rumped warbler (D.coronata) in the field and laboratory. Duringthe post-breeding preparation for autumnmigration at Churchill, Manitoba, where bothspecies must initially undergo an overlandmigration, there was no difference betweenthe two species in fat reserves, energeticcondition or patterns of corticosterone se-cretion and triglyceride levels. However, atcoastal Maine, where Yellow-rumps continueto move further south over land and Black-polls prepare for a 4-5 day, non-stop trans-oceanic flight to South America (often dou-bling their lean body mass to do so), Black-polls had higher baseline corticosterone andtriglyceride levels than they expressed atChurchill, while Yellow-rumps did not. In thelaboratory, as expected, Blackpolls retainedgreater fat reserves and higher baseline cor-ticosterone and triglyceride levels later intothe autumnal migratory period than Yellowrumps. There was no correlation betweenbaseline corticosterone and triglyceride lev-els in either species in the field or in the labo-ratory, suggesting that while elevated corti-costerone is often associated with migratoryfattening and, in some studies, found to benecessary for it to occur, its exact role in fa-cilitating the availability or production of lipidsubstrates is unclear.

57.3 HOLBERTON, R.*, WILSON, C.M.,SIMS, C., CASH, W.B., University of Maine,University of Mississippi, University of Mis-sissippi, Maryville College. The role of corti-costerone and the effects of its inhibition dur-ing the development of migratory conditionin dark-eyed juncos.

To understand corticosteroneís role in thedevelopment of migratory feeding and fat-tening, dexamethasone (DXM) was used toinhibit an increase in baseline corticoster-one often observed during migration. Dark-

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eyed juncos (Junco hyemalis) were trans-ferred from short to long-days and monitoredfor food intake, body mass, fat deposition,and plasma corticosterone for 46 days. Ev-ery 48 h for the first 17 days, controls (C, n =10) received saline while three other groupsreceived injections of either 0.09 ug (LD, n =10), 1.8 ug (MD, n = 10) or 9.0 ug (HD, n = 9)DXM/bird. Ten days after injections began,MD and HD corticosterone levels were simi-lar to each other and significantly lower thanthose in C and LD (which were elevatedabove pre migratory levels). C and LD birdsbegan to fatten and gain body mass soonafter transfer to long days. Three weeks af-ter treatments ended there was no differencein corticosterone or body mass between thefour groups. However, MD and HD birdswere significantly delayed in the onset offattening; MD birds increased mass imme-diately after injections ceased and HD birdsbegan to fatten 5-7 days later. Differences inpatterns of mass gain could not be explainedby food intake as all groups showed the samepattern of increased food intake. These re-sults suggest that an increase in baselinecorticosterone is needed to facilitate normalspring migratory fattening but, while corti-costerone may increase food intake duringthe non-migratory period in a ìstressî orìstress avoidanceî response, it is dissociatedfrom the hyperphagia that occurs as a nor-mal component of migratory condition.

S5.9 HOLBROOK, N.M.*, ZWIENIECKI,M.A., MELCHER, P.J., Harvard University.The dynamics of “dead” wood: hydrogel-mediated changes in xylem hydraulic prop-erties.

Xylem vessels are well known for theirpassive role in water transport and the pos-sibility that these tubes comprised of deadcells might possess the ability for rapid flowcontrol has never been considered. The pre-vailing view among plant biologists is thatxylem conduits have two hydraulic states;they either transport water with a constantresistance or are blocked due to embolism.The suggestion that plants can refillembolized vessels, even when there is ten-sion in adjacent conduits, may contribute tothe dynamic stability of water transport ca-pacity in plants. We discuss our empirical

and modeling efforts to understand this re-pair phenomenon, focusing on the appar-ent contradictionbetween bubble dissolutionand xylem tension. We then discuss our re-cent finding that xylem hydraulic resistanceis a function of xylem sap ion concentration.We provide data demonstrating that the ef-fect of ions on flow resistance results fromthe action of a hydrogel located in the pitmembranes. We hypothesize that the effectof ions on xylem hydraulic resistance repre-sents an important component in the regu-lation of water flow through plants. By pro-viding a mechanism by which plants can alterthe relative flow resistance through portionsof their xylem, ion-dependent hydraulic re-sistance may allow plants to control the rela-tive flows of water in a manner appropriatefor a highly branched system.

70.4 HOLFORD, K.C.*, BORST, D.W.,Purdue University North Central, Westville,IN, Illinois State University, Normal, IL. Theeffects of sinus gland extracts on transcriptlevels of farnesoic acid O-methyl transferase(MeT) in the lobster mandibular organ.

Methyl farnesoate (MF) appears to haveimportant roles in the regulation of crusta-cean reproduction, molting, and behavior.In decapod crustaceans, the mandibular or-gan (MO) is the principle site of MF synthe-sis and is inhibited by a peptide from thesinus gland (SG, a neuroendocrine tissue inthe eyestalk). This MO-inhibiting hormone(MO-IH) lowers MF synthesis in part by re-ducing the activity of MeT (the final enzy-matic step in MF production). We investi-gated the mechanisms of this inhibition bytreating eyestalk-ablated lobsters (Homarusamericanus) with a SG extract (0.2 SGequivalents) in saline-0.1% BSA or with sa-line-BSA alone (control). Hemolymphsamples were taken for MF analysis beforeand 3 hours after treatment. MO&’s werethen removed and used to determine MeTactivity and MeT transcript levels. SG treat-ment caused a 68% decrease in hemolymphlevels of MF. Control animals showed nochange in MF levels. Likewise, MeT activityof MOs from SG treated animals was 85%less (P < 0.001) than that measured in MOsfrom control animals. However, MeT tran-script levels in these two groups were not

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significantly different (P > 0.11). These dataindicate that the decrease in MeT activitycaused by MO-IH is not mediated by a de-crease in MeT gene expression. Rather, SGextract appears to act either by inhibiting thetranslation of MeT mRNA or through the post-translational modification of MeT. (Supportedby NIH-AREA grant 1-R15 HD37953-01 toDWB).

15.1 HOLLIS, D.H.*, BOYD, S.K., Universityof Notre Dame. Characterization and distri-bution of [3H]muscimol binding to a GABA-a-like receptor in the bullfrog brain.

The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) has multiple re-ceptor subtypes. The GABAA receptor iswidespread in the mammalian brain, but littleis known about GABA receptors in the am-phibian brain. Binding of the GABAA recep-tor agonist, [3H]muscimol, to membranepreparations from the brain of the bullfrog,Rana catesbeiana, was investigated in ki-netic and competition experiments. Bindingof 20nM [3H]muscimol to membranes wasspecific and could be displaced by 10uMGABA. Association binding curves showedthat equilibrium occurred rapidly, within 10minutes, and 76% dissociation occurredwithin 10 minutes as well. Binding of[3H]muscimol could be inhibited by GABA(IC50 around 100nM) and by the GABAA re-ceptor antagonist, bicuculline (IC50 around10uM). In situ autoradiography with[3H]muscimol showed putative GABAA recep-tors broadly distributed in the bullfrog brain.Specific binding of [3H]muscimol was espe-cially dense in the olfactory bulb, striatum,and hypothalamus. In the mammalian brain,muscimol is specific for the GABAA subtypeof receptor. The affinity of the bullfrog bind-ing sites for muscimol, GABA, andbicuculline supports the hypothesis that thebullfrog brain contains a GABAA receptor-like protein. Supported by NSF# IBN95-14305.

P1.17HOLT, S.M., KINSEY, S.T.*, Universityof North Carolina at Wilmington. Argininekinase flux in osmoregulating muscle cells.

We examined arginine kinase (AK) fluxas a function of intracellular osmogregulatorystate in locomotor muscle from blue crab,

Callinectes sapidus. Phosphorus nuclearmagnetic resonance (NMR) saturation trans-fer experiments were applied to measureAK flux ex vivo in isolated, superfused swim-ming leg muscle. Blue crabs were pre-ex-posed for 7 days to either 5, 17 or 34 pptsalinity prior to experiments. AK flux wasthen measured using a superfusion mediumthat had an osmolarity equivalent to thatwhich occurs in blue crabs in vivo at one ofthe three salinities above (e.g., 5 ppt exter-nal salinity = 640 mosM blood). Therefore,we could mimic the osmolarity of the extra-cellular environment surrounding the musclecells under physiologically relevant condi-tions of osmoregulation. AK flux was thenmeasured under condtions of steady-state(superfusion medium = acclimated blood os-molarity), hyperosmotic shock andhyposmotic shock. To further elucidate therole of changes in the intracellular environ-ment on AK function, we also measured AKflux in vitro. Here, we used saturation trans-fer of isolated AK in solutions comprisingdifferent levels of salts and organicosmolytes. Proton NMR was used to helpidentify the concentrations of the relevantorganic osmolytes.

P3.38HOOD, C.S.*, ASKAR, M., LoyolaUniversity, New Orleans, LA. Sexual dimor-phism in cranial size and shape: Miopithecustalapoin (Primates, Cercopithecidae).

Sexual dimorphism in cranial and caninesize and shape was investigated in the OldWorld cercopithecine, Miopithecus talapoin.A sample of 31 museum specimens (23 fe-males, 8 males) originally collected from thefield in nearby locations in Rio Muni, WestAfrica and housed in the Tulane Museum ofNatural History was used to investigate varia-tion in cranial size and shape. It is well knownthat many primate species exhibit size sexualdimorphism (SSD). A large number of fac-tors have been implicated in the origin andmaintenance of SSD in primates, includingsexual selection, social structure, functionalmorphology and ecology. Nine 2-dimen-sional cranial landmarks were collected us-ing a video-based system and were importedinto geometric morphometric software to de-scribe and analyze size and shape dimor-

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phism. Significant size (centroid size) andshape (partial warp scores) sexual dimor-phism was found among these specimens.The ratio of male/female SSD for centroidsize was 1.0377, which was statistically sig-nificant (ANOVA, F = 4.81, P < 0.05). Shapedifferences between the skulls of males andfemales reflect larger facial regions in males(longer upper jaw and palate), but largerbraincases in females.

58.1 HOOGE, M.D.*, TYLER, S., Universityof Maine, Orono. Non-muscle actin in scle-rotic components of the female reproductivesystem of acoel turbellarians.

The seminal bursa of many acoel tur-bellarians is associated with an insemi-nation canal, called a mouthpiece ornozzle, that appears sclerotized—that is,stiff and refractile by light microscopy. Themouthpiece is composed of stacks of ring-shaped cells and the stiffening element isintracellular actin, as can be seen by fluo-rescence microscopy of phalloidin-stainedwhole mounts. The function of the mouth-piece has long been assumed to be sort-ing of sperm stored in the bursa for deliv-ery to mature oocytes situated at the distalend of the mouthpiece. In species ofPseudmecynostomum (AcoelomorphaMecynostomidae), a similar actin-richstructure is situated at the functionally op-posite end of the bursa, that is between itand the vagina, which is surprisingly com-plex in this genus. It has been identified asa vaginal sphincter in descriptions ofPseudmecynostomum species, but wefind, using electron microscopy, that it isnot muscular and consists, as do bursamouthpieces, of stacks of ring-shaped ac-tin-rich cells. We propose that the bursamouthpiece has assumed a new functionin Pseudmecynostomum, perhaps by de-velopment of a secondary female porenear the distal end of the mouthpiece froman ancestor lacking the female pore.

56.3 HOOPFER, E.D., DENVER, R.J.*, Uni-versity of Michigan, Ann Arbor. Synergisticupregulation of thyroid hormone receptormRNAs by thyroid hormone and corticos-terone in tadpoles of Xenopus laevis.

Corticosteroids (CS) potentiate thyroid

hormone (T3)-induced metamorphosis inseveral amphibian species. We tested thehypothesis that corticosterone (B) inducesT3 receptor (TR) expression and that this ef-fect is at the level of transcription. Tail ex-plant cultures were initiated from St. 54 Xe-nopus tadpoles and treated for 7 days withor without T3 at 10 or 100 nM, B at 100, 500or 3400 nM, or 10 nM T3 plus B at 100, 500or 3400 nM. Tails were imaged daily, areascalculated and dry weights determined atthe end of the experiment. Separate groupsof similarly treated tails were harvested at 2and 5 days after the initiation of hormonetreatments and total RNA extracted for North-ern blot analysis. T3 at 100 nM caused sig-nificant tail regression but 10 nM T3 alonedid not. B alone caused a dose-dependentincrease in final tail dry weight. All doses ofB synergized with 10 nM T3 to cause tail re-gression comparable to the 100 nM T3 dose.At the two time points T3 alone caused a dose-dependent increase in TR-ALPHA and TR-BETA mRNAs. Interestingly, B alone alsocaused a dose-dependent increase in bothTR mRNAs. T3 at 10 nM plus B produced asynergistic effect comparable to the level ofgene induction caused by 100 nM T3. T3

caused a dose-dependent upregulation ofglucocorticoid receptor (GR) mRNA but Bhad no effect. Xenopus TR-BETA promoteractivity was upregulated by 100 nM B intransfected XTC-2 cells, suggesting a directtranscriptional action of the GR on TR-BETAexpression. These results support the hypoth-esis that B synergizes with T3 to promote tailregression by upregulating TRs, most likelyat the level of TR transcription. (Supportedby NSF grant IBN9724080)

29.5 HORNE, B. D., Ohio Unveristy. Com-parative morphology of three populations ofMexican mud turtles, Kinosternonleucostomum.

Three populations of the white lipped mudturtle Kinosternon luecostomum in southernVeracruz, Mexico were invesitgated for dif-ferences in growth rates, shell and headmorphology. Turtles that were inhabiting alarge temporary body of water were consid-erably different in morphology and growthrates when compared to two populationsfound in permanent water bodies. It is not

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known if the resulting differences are theresults of an differential physiological re-quirements or from differing levels humaninduced mortality. Natural history differencesamong the populations will also be dis-cussed.

P3.52HOUCK, L.D., WURST, G.Z.*, MOORE,F.L., Oregon State University, Corvallis, We-ber State University, Ogden, UT, OregonState University, Corvallis. Androgen levelsin breeding Utah tiger salamanders.

Many recent papers have investigatedthe relationship between plasma levels oftestosterone (T) and male behavior duringthe breeding season. One question of inter-est is whether male reproductive behavioris associated or dissociated with maximallevels of circulating T. Data concerning pat-terns of association are scarce for amphib-ians, particularly for salamanders studied inthe field. We measured sex steroid levels (T,DHT, E) for 6 adult male tiger salamanders(Ambystoma tigrinum nebulosum) collectedduring their spring breeding season fromponds in the Wasatch Mountains nearOgden, UT (elev. 8000 ñ 8500 ft.) Bloodsamples were taken within 5 minutes of cap-ture. Mean hormone values (range) were: T= 2.25 (0.3 - 6.22) ng/ml, DHT = 481 (114 -1785) pg/ml, and E = 17 (7 - 28) pg/ml. Thesevalues are comparable to plasma levelsmeasured for spring-breeding Colorado A.tigrinum that are neotenic (aquatic adultsbreed despite retaining larval morphology.)The dissociated pattern described for thesetwo A. triginum populations is in contrast withmaximal T and DHT levels recorded for a fallbreeding congener, A. opacum. These datasuggest that elevated levels of plasma an-drogens are not required for concurrentbreeding behavior in spring-breedingambystomatid salamanders.

68.6 HOUSEMAN, J. G. *, University of Ot-tawa, Biology, Ottawa, Ontario. Incorporat-ing digital media and new technologies intoan introductory zoology course: experiencesand reflections.

This paper reports on seven years of per-sonal experience on using digital media andnew technologies for teaching IntroductoryZoology, and looks back on some of the

things that worked along with some thatdidn’t. University of Ottawa is Canada’s larg-est bilingual institution and teaching materi-als for our francophone students are non-existent. As a result, our initial, and naiveobjective for using new technologies was tocreate the required materials in both lan-guages. Complications, not the least of whichwas copyright, required that we create newmaterials and these are available in themedia bank BIODIDAC that currently con-tains over 4,000 items optimized for digital,rather than print use (a http://biodidac.bio.uottawa.ca”). Media fromBIODIDAC is used in lectures as PowerPointslides, a variety of web based self evalua-tion tools, and a multimedia application de-signed to enhance understanding of classi-fication and biology of the various speci-mens that students encounter in the lab. Col-lectively referred to as Digital Zoology (©McGraw-Hill Higher Education, http://www.mmhe.com/zoology), the material is notintended to replace lab specimens, dissec-tion, nor traditional instruction. Instead, Digi-tal Zoology gives students an opportunity tosee the dissected version of a specimen be-fore the lab and a tool for review, referenceand exam preparation. For teachers, it pro-vides the resources required to effectivelyuse new technologies in either lectures orlabs and at their own pace. Strategies forincorporating new technologies into teach-ing, student reactions to Digital Zoology, andsome of the tricks and traps that were en-countered along the way will be discussed.

13.6 HOWDESHELL, K.L.*, RUHLEN, R.L.,WELSHONS, W.V., VOM SAAL, F.S., Univer-sity of Missouri, Columbia. Serum regula-tion of estrogenic endocrine-disruptingchemicals during mouse neonatal develop-ment.

Certain chemicals used in plastics andother products are capable of disruptingdevelopment by mimicking the action of thesex hormone estradiol, and thus are referredto as estrogenic endocrine disrupting chemi-cals (EEDCs). While traditional risk assess-ment for EEDCs has focused on high doseeffects, low-dose in utero exposure to EEDCscan alter postnatal reproductive function andphysiology. In adult human serum, EEDCs

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exhibit lower affinity than endogenous es-tradiol (E2) for serum binding proteins, whichare responsible for maintaining the free(bioactive) level of E2 in blood; this reducedaffinity translates into increased availabilityof EEDCs to bind to the estrogen receptor.We hypothesized that EEDCs will also ex-hibit low affinity for serum regulatory pro-teins during development, thus resulting ina higher bioactive fraction of EEDCs andresult in different levels of estrogen-respon-siveness dependent on dose. Neonatal micewere exposed to a range of doses of E2 andthe EEDC diethylstilbestrol (DES) by cap-sule implant on postnatal day 1-5. The ac-tual dose released from the capsules wascharacterized using tritium-labeled labeledE2 and DES. Neonatal response varied asa function of dose; uterine weight was sig-nificantly heavier (P<0.001) than controlswith low dose DES exposure (0.32 ng/24hr), while a higher dose of DES (239.17 ng/24 hr) depressed the response relative tothe low DES dose. Similar results were foundwith 10-fold higher E2 exposure; uterineweight was increased (P<0.001) above con-trols at low dose of 4.68 ng/24 hr. Ongoingresearch will be presented regarding thebioactive versus total dose of DES and E2delivered to serum and their affinity for se-rum binding proteins as well as data fromsimilar investigations with the EEDC,bisphenol A.

27.4 HOYT, D.F.*, WICKLER, S.J.,COGGER, E.A., GOEHRING, M.E, Califor-nia State Polytechnic University, Pomona,California State Polytechnic University,Pomona California State Polytechnic Univer-sity, Pomona, Colby College, Waterville, ME.A reexamination of the trot-gallop transition:insights from the study of locomotion on anincline.

Previous workers concluded that forcestrigger the trot-gallop (T-G) transition be-cause it occurred at a lower speed whenponies carried a load and, at the T-G speed,the metabolic rate was higher galloping thantrotting. We determined how incline (whichdoes not increase force) affects the T-G tran-sition speed in 6 horses (mean mass 460kg) trained for at least 6 months to run on atreadmill on the level and up a 10% incline.

First, transition speeds (the lowest speed atwhich the horse would gallop continuouslyfor one minute) were determined by chang-ing speed in increments of 0.25 m/s. Subse-quently, the horses were trained to changegait on command over a range of speedsfrom 1.0 m/s below T-G speed to 0.5 m/sabove. Metabolic rate was measured usingopen-flow respirometry. Duty factor (DF) wasdetermined using accelerometers taped tothe horses’ hooves. Accelerometer signalswere validated with high-speed (125 hz)video. For trotting, data from a diagonal pairof legs were averaged and for galloping datafrom all four legs were averaged. Statisticsreported are for paired t-tests. On an incline,the T-G speed is 0.75 m/s slower (p<0.001),suggesting that force is not the trigger. At thehighest trotting speed, DF on the incline is6% higher (p=0.018) than on the level, sug-gesting that peak ground reaction forces maybe lower on the incline and there may not bea consistent threshold. At the T-G speed onthe level, metabolic rate is 7% lower(p=0.009) galloping than trotting and at theT-G speed on the incline (5.08 m/s) there isno difference in metabolic rate (p=0.09), in-dicating metabolism may be the trigger. Un-der both conditions DF at the T-G speed islower when galloping than trotting.

21.2 HSIEH, S.T., Harvard University. On-togenetic 3-D kinematics of water running ingreen basilisk lizards (Basiliscus plumifrons).

Most research on tetrapod locomotionhas focused on movement over solid sub-strates. The question of how animalslocomote on fluid substrates is just begin-ning to be explored. Basilisk lizards areknown for their ability to run across the sur-face of water to evade predators. Previousresearch indicates that this method of es-cape depends largely on how much forcethe animal generates when slapping thewater, relative to its body mass. I ran eightgreen basilisk lizards (Basiliscus plumifrons)across a 3.7 m long water track. Animalsranged in size and age from two week-oldhatchlings to year-old juveniles (2-60g).Runs were filmed with two high-speedRedlake video cameras operating at 250fpsand 1/2500 shutter speed. Digitized coordi-nates from each camera were transformed

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into three dimensions using direct lineartransformation. I divided each stride into fourphases: slap, stroke, upwards recovery, anddownwards recovery. In comparison to astride on land, the slap and stroke phasesare analogous to periods when the foot is incontact with the ground, while the recoveryphases are analogous to when the foot isnot in contact with the ground. Preliminaryresults suggest that there is extreme varia-tion in the kinematics of running, both withinand between individuals. Within one run, ve-locity may vary by as much as 18% (87.9 to107.2 cm/s); and the slap may occur with thetoe first contacting the water (toe strike), orthe whole foot contacting the water (flat-footstrike). Equally large variations could be ob-served in 3D angular motions of the hip,knee, and ankle joints. However, while con-tact time (tc, slap and stroke phases com-bined) may last between 0.040s and 0.064s,duty factor (tc/stride period) appears to berelatively invariant (0.458±0.013, mean ± se).

P3.86HSIEH, T., ROSARIO, C., DUAN, C.*,University of Michigan, Ann Arbor. Insulin-like growth factor (IGF) binding protein-5stimulates cell motility through an IGF-inde-pendent mechanism that may involve in itsnuclear translocation.

Porcine vascular smooth muscle cells(VSMCs) secrete insulin-like growth factorbinding protein-5 (IGFBP-5). In this report,we show that IGFBP-5 regulates VSMC mo-tility through an IGF-dependent as well asan IGF-I-independent mechanism. The mi-gration-promoting effects of IGFBP-5 and/orIGF-I were analyzed by a trans-well migra-tion assay (directed migration) and a goldparticle cell motility assay (random motility).IGF-I is a strong regulator of directed migra-tion in VSMCs. When incubated with IGF-I atequal molar concentration, IGFBP-5 causeda 3.6-fold increase in directed migration to-wards IGF-I. IGFBP-5 alone caused a sig-nificant increase in basal migration and ran-dom motility. While addition of an IGF neu-tralizing antibody abolished the chemotac-tic effect of IGF-I, it did not affect the IGFBP-5-induced changes, indicating such changeis not due to the interaction between IGFBP-5 and endogenous IGF-I. To investigate the

IGF-I-independent mechanism(s) thatIGFBP-5 utilizes to alter VSMC motility, thenuclear localization of IGFBP-5 was exam-ined by immunocytochemistry. IGFBP-5 waseasily detectable in the nuclei of culturedVSMCs. When added to cultured VSMCs,Cy3-tagged IGFBP-5 was translocated intonuclei. In addition to a 1.7 fold increase inIGF-I-induced migration, targeted express-ing of IGFBP-5 in VSMC nuclei resulted in a6-fold increase in the basal migration andmotility in the absence of IGF-I. These find-ings suggest that IGFBP-5 plays an impor-tant role in regulating VSMC motility througha ligand-independent mechanism that mayinvolve in nuclear translocation of this uniqueIGFBP (Supported by NIH R01HL60679 andNSF Grant 978911).

P3.64HUANG, L., BARTEL, R.C.*, DENVER,R.J., University of Michigan. Thyroid hor-mone promotes cell proliferation, migrationand differentiation in the Xenopus laevis tad-pole brain.

The essential role of thyroid hormone (T3)in amphibian metamorphosis has been un-derstood for some time. However, the mecha-nisms by which it causes pleiotropic effectsremain unknown. Our group seeks to char-acterize the molecular action of thyroid hor-mone in the larval brain. In this study, weinvestigated the effects of thyroid hormoneon cell proliferation, migration and differen-tiation during metamorphosis of the Xeno-pus tadpole. For cell proliferation studies,premetamorphic tadpoles were treated with500 nM Bromo deoxyuridine (Brdu) with orwithout 50 nM T3 for 24, 48, 72 and 96 hours.Samples were then processed for Brduimmuno-histochemistry (IHC) or in situ hy-bridization for the thyroid hormone receptor(TR) ALPHA and BETA isoforms. Our pre-liminary IHC and in situ analyses demon-strate that T3 dramatically increases cell birthwithin the periventricular zone and that bothTR-ALPHA and TR-BETA messages are el-evated in this region. We are currently at-tempting to colocalize these signals withBrdu immunoreactivity. In our migration stud-ies, animals were pulsed in 500 nM Brdu,cleared for 24 hours and then treated with orwithout 50 nM T3 for 24, 48, 72 or 96 hours.

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Brdu immunoreactivity is weaker and moredispersed throughout the brains of T3 treatedanimals. Furthermore, most of the Brdu im-munoreactive cells in T3 treated brains haveelongated nuclei, which is characteristic ofmigration. Together these data suggest thatT3 treatment shortens cell cycle and accel-erates cell migration away from theperiventricular zone.

P2.52HUBBARD, J.M., TEA, National Sci-ence Foundation/Anchorage School. Bring-ing active science to classroom and com-munity with antarctic chemical ecology re-search.

Few students, teachers or members ofthe general public participate directly in cut-ting-edge research and therefore fail to de-velop a full understanding of scientific is-sues. A community of teachers and re-searchers, supported by the National Sci-ence Foundation, have created the Teach-ers Experiencing Antarctica and the ArcticProgram to expand the impact of polar re-search. In March and April 2000, I assistedresearchers from the University of Alabamaat Birmingham (J. McClintock, C. Amsler, K.Iken) and the Florida Institute of Technology(B. Baker) with their research at Palmer Sta-tion on the Antarctic Peninsula. We investi-gated the ecological roles of bioactive com-pounds in marine macroalgae and benthicinvertebrates. During this time students,teachers and other interested parties sharedour research experience through electroniccommunication. Topics included SCUBA div-ing, sample collection, laboratory experi-mentation and chemical analysis. Theteacher participation in field research pro-vided a rich basis for public education anddevelopment of resources and materials.Through casual observation, children andadults taking part in these research-relatedactivities, workshops and presentations ap-pear to be more likely to follow upon theircuriosity, show a greater intrest in sciencetopics, better understand the research pro-cess and gain a greater awareness of therelevance of science.

S5.8 HUEY, R.B., University of Washington,Seattle. Behavior as a buffer of environmen-tal change.

A common view is that animals andplants differ fundamentally in the way theyinteract with the physical environment. Forexample, animals are generally much moremobile than plants and thus are better ableto use behavior to ameliorate environmen-tal change. If this is the case, then plantsmight be more likely to respond to environ-mental change via evolutionary shifts inphysiological sensitivity rather than by be-havioral shifts. I review how behavior canfunction as a buffer of environmental change,and then address whether behavioral op-tions do in fact differ between plants andanimals. I use examples drawn from the lit-erature of ectotherm thermoregulation.

28.3 HULSEY, C.D.*, WAINWRIGHT, P.C.,GRUBICH, J.R., University of California,Davis, University of California, Davis, FloridaState University Theoretical and empiricaldiversity of anterior jaw functional feedingmorphology.

Using both computer simulations andmorphometrics of 81 species of labrid fishes,we explored morphospace occupation andfunctional consequences of design in theanterior jaws four bar linkage. This linkagemodel abstracts the mechanical propertiesof the feeding apparatus and is composedof four physical links: the lower jaw, the max-illa, the nasal, and the suspensorium. If oneangle between any two of the links and achange in that angle are designated, an in-dex of how motion is transmitted through thelinkage, KT, can be calculated. Higher KTsrepresent increased angular rotation of themaxilla per unit angular change of the lowerjaw. By changing single links in a hypotheti-cal morphospace, we found increases in therelative length of the lower jaw or nasal in-creased KT. Alternatively, increases in themaxilla or suspensorium generally de-creased KT. We also modified starting angleand input angle to determine how the con-figuration of linkages influenced KT. Differ-ences in starting angle, the initial angle be-tween the suspensorium and lower jaw, gen-erally had a large effect on KT. However,changing input angle, the angular rotationof the lower jaw, had little effect on KT. Theempirically measured linkages suggestlabrid anterior jaws have diversified, with a

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few notable exceptions, into all mechanicallyfeasible morphologies with KTs between 0.3to 1.2. We also analyzed the correlation be-tween KT and the principal components(PCA) of all the labrid linkages. We found KTwas correlated with PC2 and PC3 butuncorrelated with PC1, interpreted as size.These correlations suggest that the skeletalstructure in labrids that transfers motion fromthe lower jaw to the maxilla has diversifiedalong at least two independent shape axes.We discuss the relevance of this to the di-versity of species and feeding modes withinlabrids.

P2.39HUMFELD, S.C., University of Mis-souri-Columbia. Satellite male greentreefrogs are competitively inferior.

Individuals of different competitive abili-ties or in certain environmental circum-stances adopt different alternative matingtactics as a conditional strategy. Male greentreefrogs (Hyla cinerea) primarily produceacoustic signals to attract females; however,satellite males do not produce advertisementcalls and attempt to intercept and mate withfemales attracted to another calling male.Satellite males are not incapable of calling;they may switch tactics within and betweennights. In an observational field study, I re-corded advertisement calls and body mea-surements of males adopting calling andsatellite mating tactics as a preliminary in-vestigation of the intrinsic and extrinsic fac-tors that lead males to adopt alternativemating tactics. Satellite males were signifi-cantly smaller, less weighty and in poorercondition than calling males (P < 0.04). Re-peated measures analysis of frogs observedusing both tactics indicates the existence ofsize-independent mating tactic choice basedon condition; seven of eight males observedusing both tactics were in poorer conditionas satellites (P < 0.03). Satellite males pro-duced higher frequency advertisement callsthan callers (P < 0.02), which are less attrac-tive to females choosing mates. When theeffects of mass on frequency are statisticallyremoved, satellite males still produce higherfrequency calls. A significant negative cor-relation (r = -0.30, P < 0.05) between condi-tion and call frequency within the popula-tion suggests that poor condition may con-

strain males to produce unattractive, high-frequency advertisement calls. I concludethat males adopting the satellite mating tac-tic are at a competitive disadvantage for ob-taining mates using the calling tactic andmay maximize their opportunities for matingby parasitizing males more likely to attractfemales.

55.2 HUNT VON HERBING, I.*, CASHON,B., University of Maine, Orono, ME. Sicklingin fish red blood cells.

The occurrence of the mutant hemoglo-bin Hb S in human red blood cells resultsin sickle cell anemia. In otheranimals,oxygen-linked sickling of redblood cells is largely unknown.In Atlanticcod red blood cells under oxygenatedconditions cell morphology appears nor-mal, but under low-oxygen conditions he-moglobin crystallizes resulting in sickledcells. To determine the oxygen linkage ofthis sickling phenomenon we insertedwhole red blood cells of a freshly killedjuvenile cod into a 1 mm thick glass cu-vette and monitored changes in the mor-phology of the cells and formation of crys-tals using a compound microscope.Imageswere relayed through a high-resolutioncolor video camera to a computer and cap-tured using the OPTIMAS image analysissystem. Simultaneously with the changeof cell morphology we were able to moni-tor the spectral shift from oxy to de-oxy he-moglobin. We found that although 99% ofthe red blood cells contained hemoglobincrystals and were sickled, the shape of thered blood cells were not drastically altered.As a result, although oxygen transport maybe modulated by the formation of crystals,transport within the vascular system maynot be impeded under conditions of hy-poxia. This differs from human sickle cellsin which red cell morphology is radicallydistorted leading to occlusions within thevascular system which cause immensepain to the patient. Exposure to carbonmonoxide reversed the sickling morphol-ogy. Sickling therefore appears to be ligandlinked which is analogous to human sicklecell hemoglobin. Of the 12 other fish spe-cies tested, sickling occurred in 6 and ap-

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peared to be independent of life historystage and stock origin. However, sicklingmay be temperature dependent and be anadaptation to specific thermal regimes.Benefits of the sickling trait for survival andthe reasons for its evolution in fishes isstill unclear and is currently under investi-gation.

S1.10HUNT, R.E., Indiana University South-east. Mating behavior in leafhoppers andtreehoppers: involvement of vibrational sig-nals in male-male competition and femalepreference.

The evolution of communication systemsis strongly influenced by the types of signalsused by animals and the environmentthough which they are transmitted. For ex-ample, acoustic signals are transmitted rap-idly over great distances and the environ-ment influences signal fidelity in predictableways. Thus, sexual selection acting on sig-nals and receiver mechanisms is possibleand has resulted in competitive interactionsamong males and female preference inmany insect and vertebrate taxa. In con-trast, sexual selection is generally thoughtto be unlikely in organisms that use vibra-tional signals on plants because of their shortrange. I review recent studies of the leaf-hopper Graminella nigrifrons that show thatsexual competition among males involvesvibrational signals. Analyses of field andlaboratory recordings reveal that males al-ternate calls (i.e. chorus) and playback ex-periments reveal simple rules that regulatechorus structure. It is further shown that avoid-ing call overlap is adaptive in that it in-creases a male’s mating success when in-volved in a scramble competition for accessto a responding female. I also summarizeongoing studies of the treehopperEnchenopa binotata which suggest that fe-males discriminate among males based oncharacteristics of their vibrational signals.

60.1 HURTT, B.C.*, BEKOFF, A.C. Univer-sity of Colorado at Boulder. Modulation ofthe walking motor pattern in chicks due toasymmetric loading of the flexor muscles.

Rhythmic motor patterns, such as walk-ing, can be characterized by various com-ponents of the movement cycle using a vari-

ety of techniques, including kinematic andelectromyographic (EMG) analyses. Normal,unloaded walking motor patterns are asym-metric: extension duration is longer than flex-ion, and extensors are active for a greaterpercentage of the cycle period than flexors.One significant question of interest concernsthe role sensory input plays in establishingand modulating various rhythmic motor pat-terns such as walking. Specifically, we wereinterested in examining the changes in walk-ing motor output in chicks following loading,and subsequent unloading, of the legs withweights. Eight day old chicks walked underthree conditions: without weights for 10 min-utes (PRE), with small, 8 gram leg weightsplaced below each ankle for 10 minutes(WTS), and after removal of the weights for10 minutes (POST). Kinematic markers wereplaced at five points and digitized to deter-mine joint movement at the three major legjoints: hip, knee and ankle. EMG analysiswas conducted by implanting electrodes inantagonistic muscles at each of the threemajor leg joints. The WTS condition resultedin an increase in extension (stance) as wellas alterations in the characteristics of stance,while flexion decreased. In response to theincreased load, both extensor and flexoractivity increased in duration, resulting in anoverlap of antagonist bursts. The POSTcondition did not show a complete recoveryto the normal walking, or PRE, level by ei-ther kinematic or EMG measures. Rather, itindicated a progressive but incomplete re-covery of normal walking at 10 minutes. Inall three conditions, extension remainedhighly correlated with cycle period. However,flexion and flexor activity became morehighly correlated with cycle period duringWTS and POST.

41.2 HUSKEY, S.H.*, TURINGAN, R.G.,Florida Institute of Technology. Variation inprey-resource utilization and oral jaw gapebetween two populations of largemouthbass, Micropterus salmoides.

Ontogenetic changes in diet and jawgape were compared between two popula-tions of largemouth bass, Micropterussalmoides to test the hypothesis thatecomorphology varies among broadly dis-tributed fish populations. Two hundred sev-

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enty-two temperate (southwest Michigan) M.salmoides and 265 subtropical (east-cen-tral Florida) conspecifics were analyzed forfood habits and oral jaw gape height andwidth. Percent volumetric contributions of fourfunctional prey categories (plankton, insect,crustacean, and fish) were compared amongfish-size classes to determine if stage-spe-cific differences in prey consumption existedbetween populations. Subtropical M.salmoides shifted from feeding on planktonand macroinvertebrates to piscivory by20mm standard length (SL); and stoppedconsuming plankton by 29mm SL. Temper-ate largemouth bass did not becomepiscivores until 37mm SL and continued uti-lizing plankton up to 69mm SL. Followingthe onset of piscivory, 100-260mm SL sub-tropical bass began utilizing more crusta-ceans than fish. In contrast, temperate M.salmoides consistently fed on fish followingthe onset of piscivory. Variations in food hab-its were associated with differences in gapesize between temperate and subtropicalpopulations. Temperate largemouth basshad significantly larger gape height andwidth than subtropical bass. Althoughpiscivory is a well-known feature of M.salmoides, the ontogeny of piscivory mayvary between locations. We hypothesize thatintraspecific differences in jaw gape may berelated to variations in prey-resource utili-zation.

31.3 HUTCHINSON, J.R., Univ Calif. 2-Dquasi-static simulations of stance and gaitin Tyrannosaurs and other tetrapods.

Could the hindlimb muscles of a mas-sive biped such as Tyrannosaurus supportthe stresses of running? I report preliminaryresults from biomechanical computer simu-lations of the net muscle moments requiredto maintain static equilibrium during bipedalstanding (with extrapolations to mid-stanceof walking and running) in Alligator, Gallus,Homo, Tyrannosaurus, and other tetrapods.Using data such as body segment dimen-sions, joint angles, and muscle architecture,I model how much volume of hindlimbmuscle must be active to balance the mo-ment of the ground reaction force at eachjoint. The models predict that the net musclemoments that the hindlimb muscles of Alli-

gator can generate could not support bipe-dal running, whereas Gallus and Homo re-quire a fairly low volume of active hindlimbmuscle even to run. Thus my simulationscompare favorably with data from living sub-jects. My models of Tyrannosaurusin vari-ous stances estimate that a huge volume ofactive hindlimb muscles would be requiredfor running. In preliminary analyses, roughly20-30% of the body mass would need to behindlimb joint extensors. The knee jointmoment is especially sensitive to the stancethat is input. Was there sufficient hindlimbmuscle volume to allow running in Tyranno-saurus? I demonstrate what assumptionsmust be made to conclude either that Tyran-nosaurus lacked sufficient muscle volumefor running, or that it did have sufficient mus-culature. This shows how sensitivity analy-sis of unknown variables is vital for quantita-tively bounding the range of possible loco-motor performance in extinct organisms andfor minimizing speculation.

S8.10HYNEMAN, W., Walt Disney Corpo-ration, The Secret Lab. Creation of an ani-mated human musculo-skeletal system.

In spite of enormous interest, realisticanimation of the range of movements of thehuman skeleton has not yet been achievedby existing bio-medical software. Utilisingcommercially-available three-dimensionalscans of the human skeleton and range ofmotion data compiled from the scientific lit-erature, a model of the human musculo-skel-etal system was created in the software pack-age Maya. The foundation for digital move-ment in this model, as in life, is to be found inthe complex workings of the axial skeleton.This paper will address some of the prob-lems involved in the creation of this anima-tion for the entertainment industry, as wellas highlighting the potential such modelinghas for improving the quality of informationpresented in the scientific literature. Videoclips of this animation will be presented.

17.6 ILSE, L.M.*, HELLGREN, E.C., Okla-homa State University, Stillwater. Porcupines,pinyon pines, and pine engravers: what’s theconnection?

Understanding linkages among differenttrophic levels is important to the conserva-

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tion and management of ecosystems. Thegoal of this research was to test the hypoth-esis that porcupines, Erethizon dorsatum,predispose the papershell pinyon pine,Pinus remota, a Pleistocene-relict species,to colonization by pine engraver beetles ofthe genus Ips. We studied porcupine ecol-ogy, pinyon pine physiology andphysiognamy, and beetle-pine associationson a study area in the southwestern EdwardsPlateau from June 1997 to August 1999 toelucidate relationships among these 3 or-ganisms. Porcupines primarily were locatedin pinyon pines. Pines damaged by porcu-pines were greater in girth (P < 0.006), taller,(P < 0.001), and had greater resin flow rates(P < 0.001) than paired undamaged trees (n= 183 pairs on 20 transects). The distribu-tion of bark beetle infestations varied (P <0.01) between damaged and undamagedtrees. Although attacks by beetles were evi-dent on both types of trees, successful colo-nization was greater on pines damaged byporcupines. Intensity of porcupine attack,indexed by number of feeding scars andamount of bark removed, was also associ-ated with greater colonization rate by barkbeetles. Our data on these interspecific re-lationships are of regional interest relativeto conservation of this unique pinyon-juni-per woodland, and of wider value as a modelsystem showing the role of distinct phyla thatdefine community structure in forest andwoodland ecosystems.

S2.5 INNIS, J.W., University of MichiganSchool of Medicine. Integrative biology andthe developing limb bud.

The identification or selective construc-tion of mutations within genes has allowedresearchers to explore the downstream ef-fects of gene disruption. Much informationhas been generated and knowledge hasadvanced rapidly. However, a limitation inour assessment of the consequences of con-ditional changes, and thereby our under-standing of roles or function, is the degree towhich we examine the effects of our manipu-lations. It is also clear that linear associa-tions are incorrect models for describing de-velopment, and newer methods now allowus an opportunity to practice an integrativebiology. In our attempts to explore the con-

sequences of Hoxa13 disruption in mice andhumans, it has become clear that a full un-derstanding may only be achievable by tak-ing a broader approach with a long-termview. Fundamental questions relative to Hoxgene function in vertebrates including howmany target genes, what degree of overlapin target genes exists, what magnitude ofmodulation is exerted, which genes are ac-tivated versus repressed, and what classesof molecules are involved need to be ex-plored if a thorough conceptual understand-ing is desired. To this and other ends, wehave undertaken a comprehensive analy-sis of the expression of genes within devel-oping limb buds of mice. Our efforts will fur-ther the 1) exploration of the broader ge-netic relationships of expressed genes, 2)determination of parallels or variations in tar-get usage for a given gene in different tis-sues and between different organisms, 3)evaluation of limb patterning mechanismsin other animal model systems, and 4) ex-ploration of gene expression hierarchiesregulated by HOX proteins in developmen-tal systems.

S6.11IRSCHICK, D.J., University of Califor-nia, Berkeley. Evolutionary approaches forstudying functional morphology: examplesfrom studies of performance capacity.

Without evolutionary information, theadaptive significance of interspecific differ-ences in both morphology and function aredifficult to discern. Here, I outline the utility ofapplying evolutionary approaches to func-tional morphology in general, and perfor-mance in particular by using two model sys-tems. First, I test the hypothesis that perfor-mance capacities can predict both the aver-age habitat use and habitat breadth thatAnolis lizard species use. I also ask whetherone can predict the kinematic characteris-tics of species based on their morphologicaland performance characteristics. To answerthis latter question, I rely on data from thethree-dimensional kinematics of high-speedlocomotion in lizards. Using an explicitlyevolutionary approach for both studiesshowed that performance capacities wereexcellent predictors of habitat use in Anolislizards. In addition, while there was not aglobal correspondence between morphol-

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ogy, performance and kinematics in lizards,certain key morphological variables wereexcellent predictors of performance capaci-ties. Both studies are good examples of theutility of incorporating evolutionary and eco-logical information for understanding howspecies specialize to their environments.

21.6 IRSCHICK, D.J.*, JAYNE, B.C.,University of California, Berkeley, Universityof Cincinnati. A comparative field study ofthe arboreal locomotion of lizards.

Few studies have rigorously quantifiedthe habitat and movements of arboreal ani-mals, particularly in a comparative context.We quantified the available habitat, habitatuse and movement patterns of three mor-phologically different arboreal Anolis lizardspecies at a field site in Jamaica (A.lineatopus, A. grahami and A. valencienni).We focused primarily on how the incline anddiameter of perches affected the preferredspeed of locomotion. The habitat was domi-nated by narrow perches (70% of percheswere less than 1 cm diameter) and steepinclines (44% of the inclines were greaterthan 70 degrees). All species used steepinclines at similar proportions as availablein the habitat, but they also used shallowinclines (<25 degrees) at greater frequen-cies than available in the habitat. One spe-cies (A. valencienni) primarily used narrowperches, whereas the other two species pri-marily used broad surfaces, despite the pau-city of such perches in the habitat. The ma-jority of movements were short in distance(<15 cm), and relatively slow. For example,for A. grahami, 90% of the speeds were lessthan 40% of maximum capacity. Two spe-cies (A. valencienni and A. grahami) tendedto move on steep uphill surfaces more oftenthan on steep downhill surfaces, but A.lineatopus exhibited the opposite trend.Multiple regression analyses revealed thataverage speed per movement was signifi-cantly affected by the distance per move-ment, incline, perch diameter and perchheight. Lizards moved more slowly whenthey were on steep uphill compared to steepdownhill perches, and also when they wereon broad compared to narrow perches. Thiswork was supported by the National ScienceFoundation (IBN 9983003)

P2.30IYENGAR, E.V., Cornell University,Ithaca, NY. To steal or not to steal? That is thequestion. Suspension feeding versuskleptoparasitism in a marine snail.

Although suspension feeding is a domi-nant feeding mode in the marine realm, isperformed by members of many diversetaxa, and has evolved at least seven timeswithin the prosobranchs, suspension feed-ing is rare among snails. In a group that ap-pears extremely versatile, why arenít moresnails suspension feeders? In order to ap-proach this question, I am studying the ma-rine caenogastropod Trichotropis cancellata.This snail is capable of suspension feeding,but the majority of its populations also par-ticipate in kleptoparasitism, usually stealingfood from tube-dwelling worms. TheTrichotropis/worm symbiosis is a systemwhere a suspension feeding snail is facinglimitations that can at least be reduced by ashift to parasitism. Kleptoparasitism is com-mon for snails of all sizes at sites from Wash-ington to Alaska, and proportions of thepopulation involved in parasitism varies sea-sonally. In the San Juan Islands, Washing-ton, parasitic snails have faster growth ratesand correspondingly higher fecundities thansuspension feeding snails. Host size doesnot affect growth rates in parasitic snails. Al-though host species does not appear to in-fluence snail growth rate in the summer,snails grow faster on sabellids than onserpulids in the winter. Finally, the discoverythat another species within the Trichotropisgenus is restricted to suspension feedingindicates that kleptoparasitism has arisen atleast twice within the superfamily and sug-gests possible factors driving the shift to para-sitism.

P3.25JACOBS, M.W.*, DAVIS, J.M.,SWALLA, B.J., University of Washington. Theevolution of coloniality in stolidobranch as-cidians: a phylogenetic analysis.

Coloniality and the ability to reproduceasexually may confer strong advantagesunder certain environmental circumstances.However, only a few phyla within the inver-tebrates contain colonial species. Shiftingbetween colonial and solitary lifestyles in-volves alteration of a whole suite of life his-tory characteristics, and it is possible that

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developmental or morphological constraintsmake that transition difficult to accomplish.The Styelidae is a family of ascidians in thesuborder Stolidobranchiata that containsboth compound and solitary species, as wellas several species with intermediate mor-phologies. In the ascidians, coloniality isstrongly associated with other reproductivetraits including brooding, large egg size, andproduction of large, short-lived, well-differ-entiated larvae. Solitary ascidians cannotreproduce asexually and are generally free-spawners with small eggs and simple lar-vae. To examine how many times colonialityand its associated traits have evolved withinthe Styelidae, a region of about 1000 basepairs in the central part of the 18S rDNA of27 ascidian species was used to constructphylogenetic trees. In addition, complete18S sequence was used in selected spe-cies from the original dataset to obtain bet-ter resolution on some branches with lowbootstrap support. Preliminary results sug-gest that coloniality has arisen only oncewithin the Stolidobranchs and that ‘social’species with intermediate morphologies aresister taxa to the rest of the colonial species.This implies that ancestry, rather than adap-tation, may be the key to understanding theevolution of coloniality in the Ascidians. Adetailed comparative analysis of other lifehistory and developmental traits may beginto elucidate the critical evolutionary stepsthat can lead to a switch between solitaryand colonial lifestyles.

41.1 JANOVETZ, J., University of Chicago.Feeding in serrasalmine fishes: a compari-son of suction and biting prey capture.

Most fishes capture prey by suction feed-ing, rapidly expanding the oral cavity to cre-ate an inward flow of water that transportsprey into the mouth. This type of prey cap-ture is primitive for osteichthyes and has beenthe subject of considerable research. Otherforms of prey capture can provide a valu-able contrast to this behavior but have re-ceived less attention. Biting is the dominantform of feeding in a wide variety of fishesincluding parrotfishes, triggerfishes, andcharacins of the subfamily serrasalminae(pacus, silver dollars, and piranhas). Thisstudy examines the trophic anatomy and ki-

nematics of prey capture in a variety ofserrasalmine species to correlate morphol-ogy and feeding behavior with natural diet.Measurements of jaw lever mechanics wereused to compare the biological design ofthe feeding system. Jaw lever ratios rangedfrom approximately .3 - .5 within the subfam-ily. Species that primarily bite seeds or piecesfrom animal prey tend to have lever mechan-ics emphasizing force production while spe-cies that feed on scales or whole fish havelever mechanics emphasizing velocity of jawclosing. To compare feeding behaviors,pacus (Piaractus), piranhas (Pygocentrus),and silver dollars (Metynnis) were filmed withhigh-speed video while capturing prey byeither suction or biting. Relative to suctionfeeding, biting was characterized by lowervalues for gape, gape cycle time, and hyoiddepression. These data suggest that bitingis a distinct method of feeding and thatserrasalmine fishes can modify prey cap-ture according to prey type. NSF DEB9815614; ONR N000149910184.

29.2 JANZEN, F.J., Iowa State University,Ames. Constraints on the microevolution ofType II temperature-dependent sex deter-mination.

Sex determination is a fundamental traitof organisms that reproduce sexually, yet thetremendous diversity of sex-determiningmechanisms remains largely unexplained.The origin of and variation in types of envi-ronmental sex determination (ESD) are par-ticularly enigmatic. In this talk, I explore theecological relevance and quantitative ge-netic underpinnings of an especially curi-ous pattern of ESD called Type II tempera-ture-dependent sex determination (TSD). Ifirst evaluate temperatures measured innatural nests with respect to both pivotal tem-peratures (Tpivs) of Type II TSD determinedin the laboratory. Subsequently, I estimateheritabilities of sex ratio at both Tpivs, GxEfor sex ratio, and the genetic correlation be-tween both Tpivs in common snappingturtles. The results suggest that the ecologi-cal relevance of Type II TSD is questionableand that this pattern of TSD may simply bemaintained by genetic constraints.

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47.3 JEFFERY, J.E.*, BININDA-EMONDS,O.R.P., COATES, M.I., RICHARDSON, M.K.,St George’s Hospital Medical School, Lon-don, University of California at Davis, Uni-versity College London, University of Leiden,The Netherlands. Heterochrony in amnioteevolution.

Heterochrony is thought to be a majorlink between developmental mechanismsand the emergence of phenotypic differenceabove the species level (macroevolution).Heterochronies affecting the timing of dis-crete events are of particular importanceduring organogenesis. Within vertebrates,this is the mid-embryonic period when thebody plan is specified under the control ofregulatory genes, and when major organprimordia develop. Previous studies haveidentified putative heterochronic changes(e.g. in somite formation) during this key pe-riod, but these have not been quantified ortracked systematically across evolutionaryhistory. In part, this is due to the difficultiesinherent in analysing comparative develop-mental data. We have developed a new pro-tocol, based on ‘event-pairing’, for quantify-ing heterochrony and mapping it across theevolution of different animal groups. It im-proves upon earlier event-pairing methodsby adding an en bloc comparison of the shiftsalong each branch of the tree. This can de-termine the shifts of individual events rela-tive to all other developmental events sur-veyed, and can identify the stronger trends.Using data from vertebrates, we track timingshifts in embryonic organ development.These include delayed eye development inmammals and advanced heart developmentwithin the amniotes. We explore possiblefunctional and adaptive explanations forthese shifts (e.g. the evolution of endot-hermy). We also subject the data to a parsi-mony analysis to identify instances of con-vergence (homoplasy). In future, our ap-proach may be adapted to analyse otherforms of comparative dynamic data.

P1.74JENKINS, J.L.*, SWANSON, D.L., Uni-versity of South Dakota, Vermillion. Liver gly-cogen and freezing survival in the chorusfrog (Pseudacris triseriata).

In freeze tolerant frogs, a principal com-ponent of freezing survival is the production

and distribution of cryoprotectants (glucoseor glycerol) from liver glycogen stores. Thesize of these stores limits the absoluteamount of cryoprotectant produced duringa freezing bout, consequently impactingfreeze-tolerance. Additionally, in R. sylvatica,liver glycogen is depleted as a result of mul-tiple freeze-thaw cycles. We froze chorusfrogs for 2-3 24h bouts over the winter pe-riod of 1998 and 1999 to determine the en-ergetic cost of freeze-thaw cycles in this spe-cies. Frogs surviving the initial freeze-thawbout survived subsequent freezing bouts.However, in contrast to R. sylvatica, multiplefreeze-thaw cycles failed to significantly re-duce liver glycogen stores or change glyco-gen phosphorylase activity. Freezing sur-vival was unexpectedly low, thus promptinga secondary investigation into the relation-ship between hepatic glycogen reserves,glucose mobilization and freezing survivalin chorus frogs. In all cases freezing in P.triseriata resulted in significant increases inthe levels of glucose in liver and muscle tis-sue. However, levels of cryoprotectant andliver glycogen of animals in the current studywere significantly lower than in previous stud-ies where freezing survival was better. Lowlevels of liver glycogen may be the explana-tory factor for the decreased cryoprotectantlevels and increased mortality. The frogs inthis study showed a positive correlation be-tween liver mass and liver glycogen. Cur-rently, it is unclear if this correlation can beextended to body size, but such a relation-ship seems likely.

56.6 JENNINGS, D.H.*, WEISS, S.L.,MOORE, M.C., Arizona State University,Tempe. Ontogenetic changes in embryonicyolk steroid content in tree lizards: transferof hormones from the developing embryo tothe yolk?

In oviparous vertebrates, hormones thataccumulate in the yolk during gametogen-esis regulate development and can affect avariety of morphological, physiological, andbehavioral traits. We examined yolk steroidhormone content during embryonic devel-opment in male and female tree lizards,Urosaurus ornatus. Progesterone (P), test-osterone (T), and estradiol (E2) were presentin most newly laid eggs, whereas corticos-

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terone (CORT) was detectable in fewer eggs(34%). Later in development, at day 25 ofthe 36 day incubation, yolk P levels werehigher in males than females. Levels of T,E2, and CORT at this stage were similar be-tween the sexes. Between day 25 and 30, Pdeclines in males but not in females. Otherhormones change little during this period.Unlike the other steroids measured, yolkCORT levels increased during embryogen-esis. We have also shown (1) that embry-onic adrenal glands secrete CORT prior tohatching and, therefore, may be a potentialsource for the increase in yolk CORT and(2) that CORT may be necessary for hatch-ing: only 10% of eggs treated with RU486 (aP and CORT inhibitor) hatched comparedwith 90% hatching success in eggs treatedwith vehicle or P. Although preliminary, theseresults suggest that CORT may mediatehatching in tree lizards as many of theRU486-treated eggs contained living em-bryos. Our results suggest that ontogeneticchanges in yolk steroids are more complexthan previously thought. Yolk hormone con-tent is not simply a function of maternal pro-visioning, and hormones produced by thedeveloping embryo during late stages of de-velopment also may contribute to yolk hor-mone content.

P1.56JENSEN, B.H.*, TAYLOR, M.H., Uni-versity of Delaware, Newark. The effects ofestradiol implants on lipid transport in Fun-dulus heteroclitus.

Fundulus heteroclitus (Mummichog) is aeuryhaline teleost that is common along thewestern Atlantic coast from the maritimeprovinces to Florida. This species has a semi-lunar reproductive cycle that is accompa-nied by large changes in plasma levels oftriglycerides, the production of vitellogenin(vtg), and changes in plasma lipoproteins.Estradiol implants were used in this study todetermine the role of estradiol in lipid trans-port, and gonadal and hepatic growth. Mum-michog were collected from the CanaryCreek near Lewes, DE in unbaited minnowtraps. They were maintained in the labora-tory for one month prior to implantation.Silastic implants were inserted in the perito-neal cavity through a small incision. Fish

were sacrificed on the third, seventh, andfourteenth day post-implantation. Gonado-and hepatosomatic indices (GSI and HSIrespectively), plasma levels of triglycerides,cholesterol, liproteins, and estradiol weremeasured. Preliminary results indicate thatestradiol reduced GSI, and at low doses alsoreduced HSI and messenteric fat stores.Estradiol also induced the production of vtg,and at day seven reduced plasma triglycer-ide levels. Unfortunately, plasma lipopro-teins and lipids have yet to be fully analyzedto this point. However, it is clear that estra-diol plays an important role in altering lipidtransport to accomidate spawning in themummichog.

45.5 JERNVALL, J.*, KERŸNEN, S.V.E.,THESLEFF, I., University of Helsinki, Finland.Quantifying evolutionary modification of de-velopment in mammalian molar topography.

Mammalian dentition is characterized bycomplex and diverse molar cusp patternsand subtle changes in molars are usuallythe earliest morphological evidence of mod-ern orders in the fossil record. However, theexact ways that embryonic patterning of toothshapes could change to result in the docu-mented evolution have been difficult to char-acterize quantitatively. We have developedtopographic methods using Geographic In-formation Systems (GIS) to analyze changesin developing teeth. We performed GISanalyses on cusp formation and gene ex-pression in the first lower molar of two spe-cies of muroid rodents, the house mouseand the sibling vole. The evolutionary lin-eages of muroids are well represented inthe fossil record, thus providing a good ba-sis for discerning the types of developmen-tal processes in evolutionary transforma-tions. We identify two hierarchical develop-mental processes, prepatterning and propa-gation, that can be implicated in mouse andvole molar evolution. Firstly, digital elevationmodels and cross-correlation analysis showthat evolution in lateral cusp topography, af-fecting location of cusps and crests, resultsfrom coordinated changes in molecularprepatterns preceding the first cusps. Sec-ondly, evolutionary increase in longitudinalcusp number results from accelerated lon-gitudinal growth and faster propagation of

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the established lateral topography. The di-versity of mammalian molar cusp patternsmay largely result from these two develop-mental processes, limiting the independenceof individual morphological features used inevolutionary studies. GIS analyses on organtopography and gene expression enablenew ways to quantify development and evo-lution.

56.5 JESSOP, T.S., University ofQueensland, Brisbane. A review of the re-wards for the big, dumb and socially inept:interactions between the adrenocorticalstress response and life-history events ofmarine turtles.

The acute adrenocortical stress response(ASR) is an important defensive mechanismthat promotes physiological and behaviouralattributes that can increase survival of verte-brates in the face of pervasive stimuli. How-ever, some vertebrates modulate their ASRto stressors to promote alternativebehavioural and physiological functioning.In this study, I examined the association be-tween the ASR and various life-historyevents of marine turtles, an ancient reptiliangroup with an unusual life-history. In par-ticular, I have examined the capacity for modu-lation in the ASR of marine turtles in asso-ciation with key life-history events, includingnatal dispersal, ontogeny, and reproduction.An effort was made to examine this relation-ship in the presence of many natural stres-sors, such as social and environmental stres-sors, in addition to a more typical capturestressor. It was evident that marine turtlesexhibit a great capacity to modulate theiracute ASR to stressors. In particular, asadults, breeding females decrease the ASRto capture and ecological stressors com-pared to non-breeding females. In contrast,adult males exhibit partial adrenocorticalmodulation, in which intermale aggressionand courtship damage fails to induce anASR, however a typical capture stressor isassociated with a pronounced ASR. In sum-mary, there is a strong association betweenlife-history events and the ability of marineturtles to modulate their ASR. Some possibleexplanations are presented to clarify the in-teractions between the marine turtle ASRand their life-history.

24.1 JINDRICH, D. L.*, FULL, R. J., Univer-sity of California at Berkeley. Dynamic stabi-lization of rapid hexapodal locomotion.

Mechanical properties of muscles, con-nective tissues, and skeletal elements con-tribute to reducing energy costs, but can alsosimplify the control of rapid locomotion inanimals. Passive mechanical behavior of themusculo-skeletal system may play a role instability. Rapidly acting, musculo-skeletal‘preflexes’ have been hypothesized to con-tribute to disturbance rejection during rapidmovements and can augment the actions ofa neural feedback controller. To assess therole of ‘preflexes’ in the stabilization of rapidlocomotion, and to study the control strate-gies used by hexapods to stabilize locomo-tion, we subjected cockroaches (Blaberusdiscoidalis) to short-duration perturbationsduring rapid running. The perturbations weregenerated using a small device attached tothe animal’s dorsal surface, positioned justabove the animal’s center of mass. The de-vice used black powder to propel a ball bear-ing laterally as the cockroach ran along atrack. The reaction force from the explosiongenerated a perturbation to the animal’s lat-eral velocity with a force impulse of 60-70%of the forward momentum of a 2 gram cock-roach running at its preferred speed of 25cm/s. The duration of force was less than 10milliseconds. Lateral velocity began to de-crease 14 +/- 8 S.D. milliseconds from theonset of the perturbation. Cockroaches wereable to recover from lateral perturbations (i.e.lateral velocity returns to within the rangeobserved during unperturbed running) in 37+/- 10 milliseconds. The rapid recovery oflateral velocity supports the hypothesis thatfast-acting musculo-skeletal ‘preflexes’ mayplay a role in stabilizing insect locomotion.Supported by DARPA/ONR N00014-98-1-0747

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S4.5 JINKS, R.N.*, MARKLEY, T.L.,PEROVICH, G.M., EPIFANIO, C., CRONIN,T.W., Franklin and Marshall College, Franklinand Marshall College, University of Dela-ware, Lewes, University of Delaware,Lewes, University of Maryland, BaltimoreCounty. Ontogeny of vision in marine crusta-ceans.

Eyes of most adult crustaceans are spe-cialized for image formation and frequentlyfor color vision or polarization vision as well;but those of larvae probably have more ba-sic functions. In contrast, eyes of adult crus-taceans found at hydrothermal vents lackimage-forming optics and are specializedfor the monochromatic detection of dim light.We studied the ontogeny of vision in thePacific vent crab Bythograea thermydron.Adults of this species live at a depth of about2500 m, but the larvae are probably pelagic,and the megalopae swim actively to settle atthe vents. Eyes of four developmental stages(megalopa, juvenile 1 and 3, and adult), wereexamined with electron microscopy (TEM)and/or microspectrophotometry. B.thermydron megalopal visual pigment ab-sorbs maximally at ~479 nm, and is thus well-suited for detection of downwelling light.Juvenile 1 (post-megalopa) eyes have rhab-doms with orthogonal microvilli like those ofsurface crabs with imaging eyes (e.g.Hemigrapsus), but lack a dioptric appara-tus. Rhabdoms of juvenile 3 retinas are hy-pertrophied relative to those in retinas of ei-ther juvenile 1 or size-matched Hemigrapsus.Absorbance of adult visual pigment is red-shifted (peak ~489 nm) compared to that ofthe megalopae; however, TEM examinationfound no neural retina in adult eyes.Megalopal and juvenile 1 retinas may beadapted to a pelagic/mesopelagic existence,while juvenile 3 and adult retinas are bettersuited to detect the dim, long-wavelengthlight emitted by hydrothermal vents. Remod-elling of structure and function at metamor-phosis is probably a common feature in crus-tacean visual development.

P3.105 JOHN-ALDER, H.B.*, CARSIA,R.V., Rutgers University, New Brunswick,UMDNJ-School of Osteopathic Medicine,Stratford. Partial characterization of adreno-cortical cells from the eastern fence lizard

(Sceloporus undulatus).Season-specific corticosterone re-

sponses are apparent in S. undulatus (Horm.Behav. 36:39-52, 1999). These varying re-sponses may be due to season-related ad-renal programming. As a beginning point toinvestigate this hypothesis, we partially char-acterized the steroidogenic properties ofadrenal cells derived from male lizards col-lected in September, 2000. Adrenal glandswere dissociated using collagenase diges-tion and mechanical agitation. ‘Adrenocorti-cal’ cells were easily identified by their nu-merous large lipid droplets. Cells (1x105adrenocortical cells/ml) were incubated withvarious test substances for 2 h at 34.5†C.Incubations were frozen (-30†C) until radio-immunoassay for corticosterone and aldos-terone. Cells exhibited high constitutive ste-roidogenic activity with basal corticosteroneand aldosterone values of ~ 4 ng/103 cells/h and 40 pg/103 cells/h, respectively. Al-though inducible responses were blunted(roughly twice basal values), cells were ex-quisitely sensitive to adrenocorticotropin(ACTH), responding to concentrations aslow as 1 pM. Cells also responded to 8-bromo-cyclic AMP, but not to angiotensin IIor the steroidogenic precursor, 25-hydroxycholesterol. The lack of a precursorresponse is suggestive of a saturated ste-roidogenic enzyme pool and is consistentwith the high constitutive activity. Although itis unclear whether the overall responses ofthe lizard cells are related to season, thisstudy demonstrates that this in-vitro ap-proach may be useful to resolve the hypoth-esis of season-specific adrenal program-ming. Supported by NSF IBN95-05729 to H.J.-A. and USDA 00-35206-9330 to R. V. C.

71.5 JOHN-ALDER, H.B.*, HAENEL, G.J.,Rutgers. University, New Brunswick, ElonCollege, NC. Experimental and demographicanalyses of growth and sexual size dimor-phism in a lizard, Sceloporus undulatus

Sexual size dimorphism (SSD) is a com-mon phenomenon caused by a variety ofenvironmental and genetic mechanisms inanimals. In the current study, we investigatethe demography of a population of easternfence lizards (Sceloporus undulatus) to com-pare age structure and survivorship between

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the sexes, and we examine growth rates ofjuveniles under both natural and controlledlaboratory conditions to elucidate causes ofSSD in this species. Furthermore, using ourlaboratory growth data, we examine the heri-tability of juvenile growth rates. Our resultsshow that SSD develops in the field beforethe end of the first year of age (before sexualmaturity) because juvenile females growmore rapidly than juvenile males. In the labo-ratory environment, however, we observedno sexual difference in growth rates for liz-ards up to the size of maturity in the field.Thus, sexual differences in growth rate andsubsequent development of SSD in thispopulation are subject to strong proximalcontrol. We found high levels of additive ge-netic variance for juvenile growth indicatinga strong potential for selection to operate onjuvenile growth rates. However, while se-lection on juvenile growth rate could explaindifferences in growth among populations, itwould not necessarily contribute to SSDwithin our population due to the high plas-ticity in growth rate. Supported by NSFIBN9507529.

19.3 JOHNSEN,S., Woods Hole Oceano-graphic Institution, Massachusetts. Protec-tion or concealment? Ultraviolet absorptionin transparent animals.

The use of transparency as camouflagein the epipelagic realm is complicated bythe presence of ultraviolet radiation, be-cause the presence of UV-protective pig-ments decreases UV-transparency and mayreveal transparent zooplankton to predatorsand prey with ultraviolet vision. During July1999, September 1999, and June 2000,transparency measurements (from 280 to500 nm) were made on living specimens offifteen epipelagic (collection depth 0-20 m,average 11±1 m) and nineteen mesopelagic(collection depth 150-790 m, average370±40 m) species of transparent zooplank-ton from Oceanographer Canyon andWilkinson Basin in the Northwest AtlanticOcean. In addition, measurements ofdownwelling irradiance (from 330 to 500 nm)versus depth were made. The tissues fromepipelagic zooplankton had lower UV trans-parency than those from mesopelagic zoop-lankton, while the average visible transpar-

ency of the two groups was not significantlydifferent. Percent transparency was posi-tively correlated with wavelength over mostof the measured range, with a rapid de-crease below a certain cutoff wavelength. Inmesopelagic tissues, the cutoff wavelengthwas generally 300 nm. In epipelagic tissues,the cutoff wavelength was between 300 and400 nm. Twelve out of 19 epipelagic tissueshad transparencies at 320 nm that were halfor less than their 480 nm transparency val-ues, versus only 4 out of 21 mesopelagictissues. The effects of UV absorption on UVvisibility and minimum attainable depth weremodeled using contrast theory and the phys-ics of light attenuation. Because UV absorp-tion was generally significantly greater in theUVB than in the UVA (where UV vision oc-curs), and because the highest UV absorp-tion was often found in less transparent indi-viduals, its modeled effects on visibility wereslight compared to its effects on minimumattainable depth.

P3.9 JOHNSON, B. D., Iowa State Univer-sity, Ames. The phylogeography of the west-ern hognose snake.

A large fragment of the mitochondrialND2 gene was sequenced from a numberof populations to assess the rangewidephylogeography of western hognosesnakes, Heterodon nasicus. The resultinganalyses designate Las Cruces, NewMexico, as representative of a deeply an-cestral lineage and suggest an intriguing mi-gratory history that identifies the most de-rived populations of H. nasicus as being lo-cated in Texas. If supported by further analy-sis, this unusual pattern may shed light onthe post-glacial activity of H. nasicus (andperhaps other co-distributed species in theGreat Plains) and the influence of geo-graphic events on its life history. This projectalso detected evidence of a new species ofHeterodon, a conclusion strongly supportedby the molecular data and seemingly in ac-cord with prior morphological work.

P3.13JOHNSON, G.W.*, JOHNSON, J.D.,IRWIN, L. N., University of Texas at El Paso.A comparison of random genetic variationin bisexual and unisexual lizards.

We analyzed genomic variation in three

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sympatric species of Teiid lizards of the ge-nus Cnemidophorus that differ in reproduc-tive structure and karyotype, to test the hy-pothesis that genetic variation is greater inparthenoforms than in sexually reproducingsister taxa. Genetic diversity within localpopulations of C. tigris (bisexual, 2N), C.tesselatus (unisexual, 2N), and C. exsanguis(unisexual, 3N) was analyzed by the ran-domly amplified polymorphic DNA (RAPD)technique. Using four different primers, Neiísindex of similarity ranged from 54% to 87%in the bisexual species and from 37% to 72%in the unisexual species. However, the dif-ferences were not statistically significant. Thesimilarity index for Cophosaurus texanus, abisexual sympatric lizard from a different fam-ily (Phrynosomatidae), ranged from 29% to79%, and was also statistically indistinguish-able from the three Teiids. Our results do notyet support the theoretical expectation thatgenomic variation increases with the evolu-tion of parthenogenesis, at least over therelatively brief history of the hybrid speciesin this study. Supported by grants from theRCMI (G12-RR0814) and Bridges to the Fu-ture programs of NIH. We thank Dr. Eliza-beth Walsh for significant help and advice.

P2.57JOHNSON, J.I.*, SUDHEIMER, K.D.,DAVIS, K.K., WINN, B.M., Michigan StateUniversity Brain atlas of the sheep on theinternet for courses in neurobiology.

Brain specimens of sheep are convenientfor classroom instruction in neurobiology. Asan adjunct to use of these specimens, wehave prepared a histologically detailed andlabeled atlas of external features and inter-nal architecture of the sheep brain, at http://www.brains.rad.msu.edu Included are im-ages of 110 coronal sections, in 55 pairs ofsections. Both members of each pair are atthe same antero-posterior level, but one isstained to show cell bodies, and the other isstained to show myelinated fibers. Individualsections can be selected for viewing froman array of miniature “thumbnail” viewswhich includes all sections. Alternatively,sections can be selected according to theantero-posterior level indicated in views ofthe whole brain. When viewing a particularsection, labels can be viewed or hidden. Thestain can be changed from cells to fibers,

and vice versa, at any time. Progress can bemade from any section to the next, in eitherdirection, without returning to the selectionscreens. Each section image is accompa-nied by a small image of the whole brainindicating the antero-poster level of the sec-tion, and a millimeter scale. Also included inthe atlas are superior, lateral, and inferiorviews of the external surface, with externalfeatures labeled. Any of the images can bedownloaded, after securing our freely grantedpermission, for use as illustrations for coursework, or for any other non-commercial pur-pose. Supported by NSF grants IBN9814911, 9814912, and 9812712.

31.5 JONES, T.D.*, RUBEN, J.A., StephenF. Austin State University, Oregon State Uni-versity. Feather origins and the myth of “feath-ered dinosaurs”.

The origin of feathers has been linked toflight and/or insulation. Recent discoveriesof dinosaurs with feathers or presumedfeather precursors have been used to sub-stantiate the latter hypothesis. However,analyses of the nasal passages and associ-ated sinuses demonstrates that dinosaursand early birds, including Archaeopteryx,were likely to have been ectothermic and,therefore, would have no need for insula-tion. Additionally, the presence of feathers inLongisquama, a Triassic gliding archosaur,suggests that feathers did not originateamong the Dinosauria and were associatedwith origins of flight. Moreover, cursorial bird-like running style of the only unambiguouslyfeathered taxon (Caudipteryx), suggests thatit may have been a secondarily flightlessbird. Based on these data, we conclude thatfeathers preceded dinosaurs, that they wereoriginally associated with flight, and took onan insulatory role in conjunction with the ori-gins of endothermy in birds.

P3.29JOZEFOWICZ, C.J.*, MCCLINTOCK,J.M., PRINCE, V.E., University of Chicago.Duplication and evolution of vertebrate Hoxgenes: hoxa1a and orthologs.

In all metazoan species in which it hasbeen investigated, Hox genes are arrangedin clusters, with invertebrates having a singlecluster and vertebrates having a minimumof 4 clusters. The four cluster organization,

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until recently thought typical for all verte-brates, does not incorporate a growing setof data documenting more than four Hoxclusters in teleosts (zebrafish, medaka, etc.).We are currently examining differences inHox paralog group (PG) 1 gene deploymentbetween teleosts and other vertebrates inorder to test the hypothesis that the duplica-tions leading to increased Hox gene num-ber allowed evolution of new functions forHox genes in teleosts. Experiments in ourlab have established that the zebrafish PG1genes have not only an altered gene comple-ment as a result of gene duplication (4 PG1genes as opposed to 3 in mouse), but alsodiffering expression patterns in relation tothe murine PG1 genes. It has been assumedthat Hox genes are important for patterninghindbrain and more posterior structures, butzebrafish PG1 genes may deviate from thisclassic model of Hox gene function as theyexhibit expression patterns in the develop-ing midbrain. We are investigating PG1genes in a phylogenetically relevant sampleof vertebrates to infer the ancestralosteichthyan condition of midbrain expres-sion. We will discriminate between the op-posing hypotheses that (1) teleost midbrainexpression is a novelty that evolved afterHox cluster duplications, versus (2) midbrainexpression is a primitive condition that hasbeen lost in the mammalian lineage.

17.5 JUDD, T.M.*, HERBERS, J.M., Colo-rado State University. The effects of moistureand time of year on the foraging preferencesof the ant Pheidole ceres.

Colonies of the ant Pheidole ceres arefaced with an environment filled with vari-able food sources. The colony must be ableto allocate its foragers to these food sourcesin order to maximize its energy intake. In thisstudy we explored the effects of two vari-ables, time of year and moisture availability,on the food preferences of Pheidole ceres.Both field and lab experiments were per-formed in which we manipulated the envi-ronment and colony composition to see howthese variables affect the colony’s foragingbehavior and which individuals are involvedin driving the colony’s food preferences.

38.3 KAATZ, I.M., Boston University MarineProgram, Woods Hole. Structurally divergentsound producing mechanisms in a clade ofarioid catfishes function in different behav-ioral contexts.

Of the over 400 teleost fish families, 23%are known to have evolved two or more struc-turally and acoustically different sound pro-ducing mechanisms (SPMs). What is the func-tional significance of these independentlyderived SPMs? Structurally different SPMsare known to produce acoustically differentsounds (Demski, Gerald and Popper 1973).Species with multiple mechanisms providethe opportunity to study how signal designrelates to specific behavioral functions.Swimbladder and stridulation acousticmechanisms differ in frequency range, tem-poral pattern and amplitude. I test the hy-pothesis that these two SPMs function in dif-ferent behavioral contexts. Twelve speciesof catfishs in the arioid superfamily weremaintained in monospecific groups inaquaria in a sound proof room. The numberof swimbladder and stridulation sounds pro-duced in intraspecific contexts (sounds hy-pothesized as conspecific targeted signals)were monitored with a hydrophone and re-corded on VHS. The mean number of focalsamples per species was 60. The meannumber of sounds observed per specieswas 176. Sounds produced by the same in-dividuals in the disturbance context (soundshypothesized as predator targeted signals)were recorded in the field (recorded under-water while hand restrained). The meannumber of sounds produced per specieswas 468. In intraspecific contextsswimbladder sounds were more abundantin ten species (69-100% of total sounds perspecies) and uncommon in two species (20-30%). In the disturbance context stridulationsounds were more common in all except fourspecies. The relative use of swimbladder andstridulation SPMs in different behavioral con-texts was species specific.

S14.7KALTENBACH, J.C., Mount HolyokeCollege, South Hadley. ATPase immunore-activity and lectin binding in gills of larvalamphibians and fish.

Strong Na+/K+ ATPase activity is a char-acteristic of chloride cells (mitochondria-rich

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cells) in fish gills. Such cells have an impor-tant role in ion transport. To determine if simi-lar cells are also present in the internal gillsof amphibian tadpoles, paraffin sections ofgills, and of other tissues, were preparedfrom representative larval stages of the bull-frog and leopard frog (Rana catesbeianaand Rana pipiens) and from gills of the fresh-water goldfish (Carassius auratus). The fol-lowing techniques were then applied: 1) his-tochemical staining with four peroxidase-conjugated lectins for specific terminal sug-ars of glycoconjugates and 2)immunostaining with antibody to the ALPHAsubunit of avian Na+/K+ ATPase. Certainepithelial cells in gills of both tadpoles andfish stained intensely with each of the fourlectins (PNA for galactose, SBA for N-acetylgalactosamine, WGA for N-acetylglucosamine, and con A for mannose).However, ATPase reactivity was different inthe gills of the two types of animals. In con-trast to the strong ATPase immunostainingin chloride cells of goldfish gills, little or noimmunoreactivity was detected in amphib-ian gills. Yet ATPase staining was strong inthe few flask cells present within the epider-mis of tadpole skin as well as in the tubulesof the tadpole pronephric kidney. In conclu-sion, lectin staining indicated that specificterminal sugars on glycoconjugates are simi-lar in certain epithelial cells of gills of bothtadpoles and fish. Moreover, the strong AT-Pase immunoreactivity in the tadpole pro-nephric kidney (as in chloride cells of fishgills), plus the very weak activity in tadpolegills, suggests that the pronephric kidneymay play a more important role than the gillswith respect to ion transport in larval am-phibians.

P1.64KARPOVICH, S.*, TOIEN, O.,BARNES, B.M., University of AlaskaFairbanks. Does active metabolic suppres-sion occur during entry into torpor?

Captive S. parryii from Toolik Lake, Alaskawere housed at University of AlaskaFairbanks and exposed to ambient tempera-tures (Ta) of +2, -5 and -12oC. Body tem-perature (Tb) was recorded via telemetry andrates of oxygen consumption (VO2) and car-bon dioxide production were measured withopen flow respirometry to estimate the ener-

getic costs of ground squirrels during the re-entry phase of arousal episodes. Explana-tions of the mechanisms that allow hiberna-tors to depress metabolic rate during entryinto torpor are controversial. Does meta-bolic rate drop as a consequence of Q10 ef-fects accompanying decreased Tb or Tbrain,OR does Tb decrease as a result of tempera-ture-independent metabolic suppression?Preliminary data indicates that Q10 of Tb vs.VO2 for trials at each Ta (+2, -5 and -12oC)average 5, which is above the biologi-cally expected Q10 range of 2-3. This indi-cates metabolic suppression independentof body temperature. Rates of Tb coolingcurves are different for trials run at the 3 Tas,with no change in the rate of VO2 decrease.This also supports the metabolic suppres-sion theory. Tbrain data will be examined.

S10.8KARR, T.L., The University of Chicago.The microbe that roared: Wolbachia rescueof a lethal Drosophila mutation.

Wolbachia is an intracellular microbeharbored by a wide variety of arthropods in-cluding Drosophila. By unknown mecha-nisms, Wolbachia alters host reproductivebiology usually to increase its representa-tion within a population. In Drosophila,Wolbachia is closely associated with ga-metic incompatibility and has undergone ex-tensive intraspecific horizontal transfer in na-ture. Neither the molecular mechanism ofincompatibility nor the genetic interactionsbetween host and microbe responsible forits persistence are known. In this report wedescribe the effect of Wolbachia on two alle-les of the insulin receptor substrate gene,Chico, recently implicated in the insulin-re-ceptor pathway of growth regulation in Droso-phila. Both lines containing the Chico1 andChico2 alleles were found infected withWolbachia and its removal significantly re-duced the viability of Chico homozygotes. Inthe most severe case, removal of infection“phenoconverted” Chico2 to lethality. Chico2

viability was restored upon reintroduction ofWolbachia either via microinjection or back-crossing into an infected maternal cyto-plasm. The degree of rescue was depen-dent on the levels of Wolbachia present. Thisunique rescue suggests Wolbachia interactseither directly with Chico or with elements of

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the insulin receptor pathway. This is the firstdemonstration of genetic interaction be-tween Wolbachia and host signaling path-ways, and expands the repertoire of host/symbiont interactions observed in this sys-tem. These results call into question the fun-damental nature of Wolbachia symbiosisand suggests robust evolutionary dynamicsnot previously appreciated.

31.6 KATZ, E.P.*, HILLMAN, S.S.,NEOUCOM, Portland State University.Cross-sectional area of the nasal pas-sages of the odontoceti. Implications forpaleophysiology.

In search of evidence bearing on the en-dothermic dinosaur hypothesis, a recentstudy by Ruben et al. (1996) revealed thatendotherms tend to have larger nasal cross-sectional areas than ectotherms of the samemass. The reason offered for this observa-tion was that larger nasal passages areneeded to house the complex respiratoryturbinates posessed by endotherms. Whaleswere excluded from the study on the groundsthat they have no nasal turbinates. In thepresent study, the cross-sectional areas ofthe nasal passages of nine species ofOdontoceti were measured using latex casts.The regression of log cross-sectional areavs. log mass for the whales was the same asfor the endotherms of the previous study.Alternative explainations for the large nasalcross-sectional area of endotherms aresought.

P2.9A KAVANAGH, K.D.*, MORGAN, B.A.,Museum of Comparative Zoology, HarvardUniversity, Massachusetts General Hospi-tal, Harvard Medical School. Regulating dif-ferentiation in vertebrates: functional homol-ogy and evolutionary co-option in Ikarosfamily genes.

The Ikaros gene family of transcriptionfactors is important in several vertebratedevelopmental pathways. Four paralogousgenes in the family encode proteins thathomo- and heterodimerize before bindingto the DNA molecule, facilitating transcrip-tion of lineage-specific genes. In the work-ing model for the function of these genes,the proteins act sequentially to regulate theprogress of differentiation along a cell lin-

eage, with different Ikaros-family genes ex-pressed as the cells become more restrictedin differentiation potential. Recent studiesdemonstrate that in vertebrates, the genesare expressed and/or function in diverse tis-sues, including neural, epidermal, andhaematopoietic lineages. Progress in un-derstanding taxon-specific and tissue-spe-cific differences and similarities in expres-sion and function will be presented with anevolutionary perspective.

S6.5 KELLY, D. A., Mount Holyoke College,South Hadley, MA. The functional morphol-ogy of penile erection: tissue designs thatmake the floppy stiff.

Functional morphology focuses on howbiological structures work in the naturalworld; the specifics of how any structureworks depends in part on both the me-chanical properties of its materials andhow those materials are arranged withinthe structure. For example, the tissue sur-rounding the penile vascular spaces ofboth mammals and turtles is made up pri-marily of collagen fibers. The tensile prop-erties of collagen let the tissue becomestiffer as it extends during penile erection.But the specific organization of the col-lagen fibers also has a profound effect onthe mechanical behavior of the entire pe-nile hydrostatic skeleton. Because the fi-bers are arranged in an axial orthogonalarray, the erect penis is able to resist bend-ing and shape changes during copula-tion—unlike most biological hydrostats,which are flexible due to their arrangementof inextensible fibers in left- and right-handed helices. In the case of the penis, alow resistance to bending when erectcould constitute a mechanical failure of thestructure, because its primary function inboth mammals and turtles is to enter thefemale reproductive tract for insemination.

P3.92KELTY, J.D.*, NOSEWORTHY, P.,FEDER, M.E., ROBERTSON, R.M.,RAMIREZ, J.M., University of Chicago,Queens University, University of Chicago,Queens University, University of Chicago. Ef-fect of heat pretreatment on spontaneousglutamatergic and glycinergic synaptic trans-mission during subsequent thermal stress

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in the mouse pre-B-tzinger complex.Brief exposure to sublethal high tempera-

ture induces protection against a variety ofstresses (e.g., high temperature, oxidation,hypoxia) in many organisms. The breadth ofprotection conferred in this way suggests po-tential importance in defending the mam-malian central nervous system against thedetrimental effects of ischemia and hypoxia.As part of our investigation into the effects ofhyperthermia on neuronal function, we usedstandard whole-cell patch clamp techniquesto determine whether thermal pretreatmentalters the frequency of spontaneousglutamatergic and glycinergic synaptic trans-mission between neurons of the mouse pre-B–tzinger complex during subsequent hy-perthermia. Without thermal pre-treatment,heating the tissue from 30o to 40oC in-creased the frequency of spontaneous min-iature postsynaptic currents elicited by bothglutamate and glycine by 1104.1 ± 86.3%and 3582.8 ± 142.6%, respectively. How-ever, a 15 min thermal pretreatment at 39.5o

- 41oC one hour prior to such hyperthermiasignificantly reduced the increase in fre-quency of spontaneous transmission viaglutamate to 456.5 ± 43.4% above 30oCbaseline (p < 0.005) and via glycine to1120.9 ± 94.8% above baseline (p < 0.0005).Two hours following thermal pretreatment,hyperthermia-induced increases in sponta-neous transmission frequency remained sig-nificantly lower than those in tissues under-going hyperthermia for the first time (p <0.005 for both neurotransmitters). These dataindicate that exposure of nervous tissue totemperatures experienced during high fe-ver or heat stroke induces an acclimatoryresponse opposing extreme deviation fromnormal frequencies of spontaneous synap-tic transmission.

S15.7KETTERSON, E.D.*, NOLAN, Jr., V.,CASTO, J.M., NEUDORF, D.L.,GRINDSTAFF, J.L., PARKER-RENGA, I., In-diana University, Bloomington, Indiana Uni-versity, Bloomington, Indiana University,Bloomington, Sam Houston State University,Indiana University, Bloomington, IndianaUniversity, Bloomington. Using hormones toexplore adaptation and constraint in a song-

bird.We take an experimental approach to the

evolution of life histories and the nature ofadaptation and constraint. For the past 13years, we have manipulated plasma levelsof testosterone (T) in free-living male dark-eyed juncos (Junco hyemalis), a socially mo-nogamous songbird. Males caught in earlyspring receive subcutaneous silastic im-plants that are empty (C-males) or packedwith T (T-males). The dose of T simulates themaximum physiological level exhibited byunmanipulated free-living males prior tobreeding. The goals have been (1) to docu-ment testosteroneís diverse effects on a widearray of phenotypic traits and (2) to relateaffected traits to fitness in order to enhanceunderstanding of the evolution of complexadaptations. Behaviorally, T-males sing more,have larger home ranges, and are more at-tractive to females, but feed their young lessoften. Physiologically, T-males have higherlevels of corticosterone and corticosteronebinding globulin, respond more strongly tostressors, and show signs of suppressed im-mune function. Overall, T-males devote moreeffort to seeking mates and less effort to pa-rental behavior and self-maintenance. Withrespect to fitness, T-males sire more youngwith their social mates and the mates of othermales, but are less successful at rearingyoung at home. Recent work has focusedon (1) whether phenotypic effects of T ex-tend to associates of treated males (matesand offspring) as reflected in egg dimensionsand contents, offspring sex ratio, or immunestatus, and (2) potential consequences forfemales and males of a correlated responsein females to selection favoring higher T inmales.

65.2 KETTLE, C. S., ARTHUR, W., Univer-sity of Sunderland. Centipede embryology:conservation and change in early develop-ment within the Chilopoda and comparisonswith other arthropods.

Centipedes provide a good opportunityto study the evolution of segmentation, be-cause (a) different orders of centipedes havedifferent numbers of segments and (b) withinone order, Geophilomorpha, there is alsointraspecific variation in this character. How-

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ever, progress in comparative studies hasbeen hindered by a lack of basic informa-tion about embryonic development in mostcentipede groups. Here, we describe theembryology of a geophilomorph centipede,and confirm that its development isepimorphic - that is, the full complement ofsegments is complete before hatching.Thisis a derived feature within the Chilopoda,shared only with the sister-groupScolopendromorpha. It is convergent withthe well-known epimorphic system of Droso-phila.

54.3 KHAN, H.R.*, MATSUSHIMA, O.,ALKINDI, A.Y.A., SALEUDDIN, A.S.M., Sul-tan Qaboos University, Oman, HiroshimaUniversity, Japan, Sultan Qaboos University,Oman, York University, Toronto, Canada. Ef-fects of serotonin, FMRFamide-related andvasopressin-related neuropeptides on freeamino acid mediated osmoregulation in apulmonate snail.

Osmoregulatory roles of serotonin andFMRFamide-related (FaRPs) in inverte-brates have been shown in previous stud-ies. We have studied the effects of seroto-nin, five FaRPs and three vasopressin-re-lated neuropeptides on free amino acid(FAA) mediated intracellular osmoregula-tion by the kidney of the pulmonate snail,Helisoma. The levels of various intracel-lular FAAs in isolated kidney tissue pieceswere measured after 30 min in vitro treat-ment with serotonin or one of the aboveneuropeptides in physiological saline. Forcontrol, the tissues were treated in physi-ological saline alone. Compared to con-trols, the levels of FAAs increased signifi-cantly in various treatments. The treat-ments with neuropeptides were more ef-fective than serotonin. The presence ofimmunoreative (IR) substance to argininevasopressin and conopressin (vaso-pressin-related molluscan neuropeptide)were studied in the central nervous sys-tem (CNS) and kidney by immunocy-tochemistry. The IR neurons are presentin all ganglia of the CNS except the buc-cal and pleural ganglia. Large IR neuronswere found in the visceral and left parietalganglia which innervate the kidney, and

many IR fibers and varicosities in the kid-ney tissue were also seen. Osmoregula-tion by serotonin and the neuropeptidesin the snail will be discussed.

P2.72KIDD, C.*, BRAINERD, E.L., Univer-sity of Massachusetts. Abdominal pressureduring high speed locomotion in the Texasspiny lizard, Sceloporus olivaceus.

In this study we measured pressure inthe abdominal cavity of Sceloporusolivaceus at rest and during high speed lo-comotion on a trackway. During trackway lo-comotion, abdominal pressure fluctuatesrapidly around mean pressure and appearsto be correlated with footfalls. Preliminaryresults from two individuals indicate thatmean abdominal pressure increases dur-ing burst locomotion. Mean abdominal pres-sure during locomotion increased abovemean resting pressure by 3.6 ± 2.3 cmH2O(0.36 ± 0.23 kPa) in one individual and by3.5 ± 1.9 cmH2O (0.35±0.19 kPa) in a sec-ond individual (mean ± s.d.). Paired t-tests(paired pre-exercise and running pressures)showed that these increases were statisti-cally significant in both individuals(p<0.0005). It is likely that these increasedabdominal pressures are transmitted to thethoracic region since lizards lack a dia-phragm and the lungs and other internal or-gans are contained within a single cavity.Previous work has shown that lung ventila-tion decreases dramatically in lizards sprint-ing on trackways, and the proposed expla-nation is for this decrease is a mechanicalconstraint on hypaxial muscles (Carrier, D.R. 1987. Exp. Biol. 47: 33-42). We proposethat increased abdominal, and therefore tho-racic, pressures may be an additional con-straint on ventilation during sprinting in liz-ards. Supported by a Beckman FoundationUndergraduate Research Scholarship toC.K. and a National Science Foundationgrant, IBN-9875245 to E.L.B.

P3.81KIRKTON, R*, THORN, R.S., DenisonUniversity. Turning on smell: nitic oxide andthe maturation of the honeybee olfactory sys-tem.

Freshly eclosed honeybees, Apismellifera, are known to have poor sensitivityto odor, but subsequently ëturn oní their ol-

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factory system within 5-10 days after emer-gence. We repeated these behavioral ex-periments and found that young bees candistinguish odors by contact within a day af-ter they emerge, but need 4-6 days to de-velop responsiveness to airborne odors.Electroantennagrams (EAGs) correlated areduced sensory cell response with this lackof sensitivity to airborne chemicals. NOSfigures prominently in the bee olfactory sys-tem, where it aids odor memory. When weexamined young bee brains for distributionand levels of NOS, they were lower in youngbee antennal lobes. If young bees wereforced to mature quickly by isolation fromthe hive, they showed increased sensitivityto airborne odors, an increased EAG re-sponse, and elevated NOS levels. SinceNOS in the antennal lobe is from antennalsensory cells, these results suggest thatyoung bees must modify these cellsí chemi-cal sensitivity and NOS levels in order tobecome sensitive to airborne odors. Whetherthese events are causative or merely cor-relative remains to be investigated.

24.3 KIRKTON, S.D.*, HARRISON, J.F., Ari-zona State University, Tempe. Effects of allo-metric growth on oxygen sensitivity andjumping performance in the American locust.

Body size changes within instars andacross the lives of insects could have sig-nificant respiratory and locomotory conse-quences because of possible problems withoxygen delivery in larger insects. We inves-tigated the effect of across and within instargrowth on performance during repeatedjumping in the American locust, Schistocercaamericana. Larger (older) grasshoppers fa-tigued more rapidly than smaller (younger)instars, both when comparisons were madeacross and within instars. We hypothesizedthat the poorer endurance of larger grass-hoppers was due to reduced oxygen deliv-ery relative to tissue metabolic needs. Grass-hoppers ranging from 2nd instars (0.08 g) toadults (2 g) were forced to jump up to 20minutes in oxygen atmospheres rangingfrom 5 kPa O2 to 60 kPa O2. Hyperoxia hadno significant effect on the endurance timeof any age grasshopper. As juveniles in-creased in size/age endurance time became

increasingly sensitive to hypoxia; specificallyendurance time in 12 kPa O2 atmospheresrelative to that in 21 kPa O2 decreased withsize. This result suggests that larger juve-niles have less tracheal oxygen deliverycapacity (or safety margin) relative to legmuscle oxygen needs. Adult endurance timewas unaffected by hypoxia, suggesting thatleg muscle activity metabolism in adults isnearly completely anaerobic. Body sizechanges within an instar also affected re-peated jumping performance. Within the 6th

instar, grasshoppers that were four daysolder have 40% lower endurance times. Incontrast to the general trend toward reducedendurance in larger (older) animals, adultsthat were 28 days old had similar endur-ance times when compared to 50% lighter 2day old adults, suggesting that adult legsmay undergo a compensatory mechanismto improve jump performance.

1.23 KISS, A.J.*, CHENG, C.-H.C, Univer-sity of Illinois at Urbana-Champaign. Gammacrystallins of Antarctic notothenioid fishes.

The Notothenioidei suborder of teleostfishes of the Southern Ocean possess anti-freeze glycoproteins (AFGPs) that allow themto thrive in the habitually ice-laden Antarcticwater. While the AFGPs are the most promi-nent adaptation of these fishes, other pro-teins have provided valuable insight into coldadaptation - lactate dehydrogenase, tubu-lin, and acetylcholinesterase. Gammacrystallins are the major lens crystallin in fish,therefore we have begun to characterise theAntarctic notothenioid GAMMA crystallins,to eventually determine whether there areadaptive changes regarding stability andpolymerisation as a consequence of freez-ing temperatures. Gamma crystallins fromthe giant Antarctic toothfish, Dissostichusmawsoni, were isolated by size exclusionand ion exchange column chromatography.SDS-polyacrylamide gel electrophoresisshows five isoforms ranging in size between19 kD to 23 kD. A partial cDNA from thetoothfish has been obtained by RT-PCR us-ing primers designed from conserved re-gions of GAMMA crystallin sequences ofcarp. With specific primers based on thetoothfish partial GAMMA crystallin cDNA we

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have used RACE to obtain the full lengthcDNA from cold-water notothenioid speciesGymnodraco acuticeps, Pagotheniaborchgrevinki, and Trematomus hansoni, andthe temperate-water species, Nototheniaangustata (from New Zealand). Compara-tive protein sequence and structural analy-ses of the lens proteins from thesenotothenioids may be informative on whetherany evolutionary adaptations have resultedfrom environmental influence.

P2.40KLEMENHAGEN, K.C.*, RAND, M.S.,Carleton College, Northfield. An investiga-tion of opioid involvement in the modulationof reproductive behavior in the whiptail liz-ard Cnemidophorus velox.

The role of endogenous opioids in re-productive behavior has been studied in avariety of mammalian species. Additionally,amphibian locomotory behavior can bemodulated by administration of the generalopioid antagonist naloxone. The investiga-tion of the opioid system in reptiles has largelyfocused on the location and synthesis ofcentral opioid peptides; however, the behav-ioral effects of opioids have not been fullyaddressed. We are interested in the pos-sible role of opioids in reproductive behav-iors of the whiptail lizard, Cnemidophorusvelox. The reproductive behavior ofCnemidophorus involves a well-character-ized copulatory position called the “dough-nut.” In this position, the male stretches hisbody into an arc above the female and closeshis jaw tightly on her midsection. During thedoughnut, the bitefrom the male appears toimmobilize the female, allowing the copula-tory position to be maintained for severalminutes. We hypothesized that endogenousopioids mediate this temporary immobility,thus allowing the female to sustain the copu-latory position. We predicted that adminis-tration of a general opioid receptor antago-nist (naloxone) to the female would blockthe immobility response to the doughnut po-sition. The administration of high (10mg/kgbody weight) and low (1mg/kg body weight)doses of naloxone did not significantly af-fect female receptivity, the duration of thecopulatory position, or the amount of loco-motory activity compared to saline controls.

Because the peak response of naloxone inmany species is between 10-30 minutespost-injection, we plan to investigate and re-port the effects of naltrexone, a longer-last-ing general opioid antagonist, on the samebehaviors.

S3.7 KLEY, N.J., University of Massachu-setts. The evolution of prey transport mecha-nisms in snakes.

Three fundamental modes of intraoralprey transport are recognized withinSquamata. Lizards use either hyolingualor inertial transport mechanisms, both ofwhich involve bilaterally symmetrical jawmovements. In contrast, most snakes ex-hibit a unilateral jaw-ratcheting mecha-nism that is characterized by asymmetri-cal jaw movements. Given the well-cor-roborated phylogenetic hypothesis thatsnakes are derived from lizards, this sug-gests that major changes occurred in boththe structure and motor control of the feed-ing apparatus during the early evolutionof snakes. Previous studies of the evolu-tion of feeding systems in snakes have fo-cused primarily on morphological featuresthat were believed to have facilitated theelaboration of unilateral transport mecha-nisms within alethinophidian snakes. Un-til recently, however, scolecophidiansnakes have generally been excludedfrom such analyses, despite their interme-diate phylogenetic position between liz-ards and other snakes. I used high-speedvideography to study feeding mechanicsin two families of scolecophidian snakes(Leptotyphlopidae and Typhlopidae).Leptotyphlopids were found to transportprey using a bilaterally symmetrical man-dibular raking mechanism. Furthermore,the morphology of the leptotyphlopid jawapparatus suggests that prey transport inthese snakes is mediated primarily by hy-poglossal rather than trigeminal muscula-ture. In contrast, typhlopids generally usedan asynchronous maxillary raking mecha-nism during intraoral transport. As inalethinophidians, protraction and retrac-tion of the upper jaw arches in typhlopidsare controlled largely by muscles of theconstrictor internus dorsalis group. How-

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ever, differences in morphology and feed-ing kinematics suggest that the asymmetri-cal jaw-ratcheting mechanisms oftyphlopids and alethinophidians arose in-dependently.

P3.88KLOHR, S.D.*, EDER, S., KRAJNIAK,K.G., Southern IL University Edwardsville.Localization and effects of FMRFamide re-lated peptides in the earthworm crop-giz-zard.

Previous studies have shown that thecrop-gizzard of the earthworm, Lumbricusterrestris responds to FMRFamide. Re-cently, we used immunohistochemicaltechniques to see where FMRFamide islocalized in these tissues and an isolatedtissue assay to determine how they re-spond to FLRFamide, which is also foundin annelids. FMRFamide immunoreactiv-ity (ir-FRMFamide) was visualized by im-munofluorescent staining. Tissues wereremoved, fixed, embedded in paraffin, sec-tioned, and placed onto slides. The sec-tions were stained with rabbit antibodiesto YGGFMRFamide, and visualized withgoat antirabbit antibodies conjugated tofluorescene. As a control some slides werestained with preimmune rabbit serum.Slides were viewed and photographedwith a fluorescent microscope. For the bio-assay the crop-gizzard was removed, con-nected to a force transducer, and placedin a tissue bath. Mechanical recordings ofthe contractions were made before, dur-ing, and after the application of increasingconcentrations of either FLRFamide orFMRFamide. ir-FRMFamide was found infibers and varicosities innevating thesmooth muscle of both the crop and giz-zard. FLRFamide caused a biphasic re-sponse in contraction rate and amplitude.At 10 uM FLRFamide caused an increasein both parameters, while at 100 uM itcaused a decrease in both parameters.The change in rate was similar to that seenwith FMRFamide, however FMRFamideonly caused a decrease in amplitude witha threshold between 1 and 10 nM. Theseresults strengthen the hypothesis thatFMRFamide related peptides may be usedto control the movements of the crop giz-

zard. Furthermore, it appears there aredifferences in how the receptor respondsto the tetrapeptides.

P2.18KNUTZEN, M., Iowa State University.Turtles in minature: an investigation intohatchling size manipulation.

Eggs Of Apalone mutica were assignedto a yolk manipulation treatment(control,sham, 0.5 g removal, or 1.0 g removal) andincubated in moist vermiculite (-150kPa) atabout 30.5 C. Three eggs from each of 7clutches were assigned to each treatmentfor a total of 84 egg. Hatchlings began toemerge approximately 51 days after ovipo-sition. Hatching success was low amongyolk-manipulated eggs (approximately 12%;nonsurviving eggs lacked embryos andsigns of fungal infection, suggesting thatmortality occurred early in development dueto trauma caused by the aspiration proce-dure. Statistical analyses idicated aporportional relationship between egg massand hatchling massand between theamount of yolk removed and the subsequentdecrease in hatchling mass. Modifying aspi-ration procedure to improve hatching suc-cess would thus prove a valuable techniquefor experimentally manipulating neonatesize. Interestingly, however, swimming andrighting performance in the laboratory wereunrelated to any measure of bosy size. Stil,the crucial tests of the relationship betweenbody size, performance, behavior, and fit-ness remain to be investigated in the field.

S11.15 KODITSCHEK, D.E., University ofMichigan. Integrating mechanical and bio-logical hypotheses for high performance lo-comotion.

Recent years have witnessed a payoff torobotics researchers who have taken theeffort to incorporate lessons from biology intheir designs. High performance locomotion– legged robots that are both stableand maneuverable over highly varied ter-rain – now appear to be close at hand.The potential for reciprocal payback to biol-ogy arises from the formal mathematical defi-nitions and analysis that such models af-ford. Within this framework, steady state lo-comotion may be cast in terms of the localstability properties of selected periodic or-

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bits. An Attractor is a collection of orbitsagainst which arbitrary small perturbationsresult in small deviations that eventuallysettle back to it. This (local) notion of stabilityis particularly useful because it entails for-mally equivalent computationally effectiveconditions on experimental observables thatapply to almost any model of biological in-terest. In contrast, developing empiricallygrounded and mathematically well foundedparadigms for maneuverability, a non-steadyphenomenon, remains an open problem.The (global) collection of non-steady devi-ant motions that settle down to an attractorcomprise its Basin of attraction. Attractors withlarge basins and fast transients have offereduseful (hybrid) building blocks for maneu-verability in robotics. The paradigm of hybridglobal stability mechanisms may offer newdirections of experimental inquiry and con-ceptual unity in biology if: i) computationallyeffective methods can be developed for theiranalysis and design in the high dimensionalnonlinear settings relevant to animal loco-motion; and ii) the hypotheses they prescribecan be tied to specific aspects of animal bio-mechanics and physiology. Supported byDARPA/ONR N00014-98-1-0747.

25.2 KOEHL, M.* A.R. *, HADFIELD,M.G., COOPER, T., REIDENBACH, M.A.,KOSEFF, J.R., University of California, Ber-keley, University of Hawaii, Stanford Univer-sity. Can larvae of benthic animals use dis-solved chemical cues in wave-driven flow?

Can chemical cues in the water affect thesettlement of larvae of benthic marine inver-tebrates in habitats subjected to the wave-driven water flow that characterizes manycoastal habitats? We addressed this ques-tion using larvae of the sea slug Phestillasibogae, which metamorphose in responseto a water-borne species-specific metabo-lite of their prey, Poritescompressa. P.compressa is an abundant coral that formsreefs in shallow, wave-dominated habitatsin Hawaii. We used dye releases and acous-tic doppler velocimetry to characterize thewater flow above and within P. compressareefs. A flow regime mimicking the turbu-lence and waves measured in the field wascreated in a flume across a reef of P.compressa skeletons; planar laser-induced

fluorescence was used to quantify the fila-mentous small-scale spatial and temporaldistribution of cue concentrations above thereef. Tethered larvae swimming in a mini-flume exposed to temporal patterns of cuemimicking those above a reef, rapidly re-tracted their ciliated velum (the swimmingorgan) when in filaments of cue. Larval bio-assays of cue strength in field-collected wa-ter elucidated patterns in the locations on areef where water-borne chemical cues arestrong enough to induce P. sibogae larvaeto stop swimming and sink. A series of fieldexperiments monitoring the transport of lar-val mimics showed that P. sibogae larvaesink rapidly enough to be retained on thereef when wave-driven flow moves acrossit.

PPA KOHN, A.J., University of Washington,Seattle. Deadly beauties of the southernseas: integrative and comparative biologyof Conus.

I will recount the highlights of nearly ahalf century in the company of beautiful butdeadly denizens of the south seas, with em-phasis on how integrative studies acrossseveral levels of organization and compara-tive studies across species in a single taxoncontribute to understanding the evolution ofbiodiversity. I will raise (but not answer all of)the following questions: 1) The large num-ber of extant species (>500) and geologicyouth (~55mybp) of Conus indicate a veryrapid rate of new species formation. When,where and how did these speciation eventstake place? 2) Do molecular and geologicclock data integrate well? 3) In addition tohigh general species richness (GAMMA di-versity) many species co-occur at finer spa-tial scales (ALPHA diversity: up to 36 on asingle coral reef). Do these species avoidcompetition by partitioning resources, and ifso how? 4) In contrast, few species co-occurin other places. Why do some environmentssupport many species, and others few orone? 5) How do the molecular properties ofthe venom peptides (conotoxins) integratewith feeding behavior and comparative ecol-ogy? And 6) what are their applications inother endeavors, especially neurobiologyand medicine?

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P2.25KORZAN, W.J.*, SUMMERS, T.R.,MINER, H.M., MARTIN, M.L., FLYNN, M.B.,SUMMERS, C.H., University of South Da-kota, Vermillion. Manipulating a visual sig-nal of sympathetic activity: influences on so-cial status and plasma Catecholamines.

Darkening of postorbital skin in Anoliscarolinensis occurs during stressful situa-tions, and is stimulated by adrenal catechola-mines via BETA2-adrenergic receptors. Thiseyespot forms more rapidly in dominantmales during social interaction. It was hy-pothesized that eyespot darkening (greento black) is a social signal communicatingsympathetic activation and limiting aggres-sive interaction. To assess the value of theeyespot as a social signal, males pairedaccording to size and weight were paintedpostorbitally one with green paint and theother with black paint. The pairs interactedand social hierarchy was determined bycounting aggressive behaviors such as ag-gressive displays, approaches, bites andchases. Males with eyespots darkened byblack paint were dominant in 100% of inter-actions. Males with eyespots painted blackalso exhibited higher plasma epinephrine,norepinephrine and dopamine levels thanmales with eyespots hidden with green paintand controls. The potency of the eyespot asa social signal serves as a catalyst that stimu-lates or inhibits the sympathetic nervous sys-tem in aggressive interactions betweenmales. Supported by NSF grant OSR-9452894, Sigma Xi grants in aid and NSFEPSCoR graduate fellowship granted toWayne J. Korzan

P2.31KOZLOWSKI, C.P.*, MCINTYRE, J.C.,MOORE, P.A., Bowling Green State Univer-sity. The winning effect in agnostic encoun-ters of crayfish is a time dependment phe-nomenon.

Previous studies have shown that fight-ing behavior is the fundamental method fordetermining dominance between crayfish.Many factors are responsible for determin-ing dominance, including the crayfish’s pre-vious fighting experiences. It has been shownthat a crayfish that has had a previous win-ning experience by fighting another crayfishis more likely to win its next fight. This is termedthe "winning effect". In this experiment, we

tested how long this winning effect lasted byvarying the time between a crayfish’s win-ning experience and its next fight. Resultsshowed that the longer the time delay be-tween the two fights, the more likely the cray-fish was to initiate a fight, but the less likely itwas to win the fight. We conclude that whileprevious fighting experiences do influencea crayfish’s likelihood of initiating and win-ning a fight, this effect is temporary and de-creases rapidly with time. This time period isbetween forty and sixty minutes in length.The period in which the “winner effect” takesplace can play an important role in domi-nance and hierarchy formation. Further re-search needs to take into account the timebetween previous fighting experiences inorder to assess a crayfish’s chances of win-ning a fight accurately.

P3.42A KRAJNIAK, KG.*, LU, J., EDER, S.,Southern Illlinois University Edwardsville.Immunohistochemical localization of sero-tonin in the zebra mussel, Dreissenapolymorpha.

The zebra mussel, Dreissenapolymorpha, is a non-indigenous bivalvemollusc that is present in the waterways ofNorth America. Previous research hasshown that the neurotransmitter serotoninor 5-hydroxytryptamine (5-HT) can inducespawning in these animals. In other bivalvesserotonin is also involved in the control ofheart rate, smooth muscle tone, and neu-ronal activity. Therefore, we decided tosearch for serotonin in a variety of zebramussel organs and tissues, including heart,transcardiac rectum, and anterior byssal re-tractor muscle (ABRM). Specimens werecollected from the Mississippi River nearGrafton, IL and kept at 10o C until used. Tis-sues were removed, fixed in Bouin’s fixa-tive, embedded in paraffin, and sectioned inpreparation for the staining process. Thetissues were stained with rabbit polyclonalantibodies to serotonin. The secondary anti-bodies used to visualize the primary anti-bodies were goat anti-rabbit antibodies con-jugated to fluorescein isothiocyanate. All tis-sues were examined with a fluorescent mi-croscope and photographed. Control slideswere stained with serotonin antibodies,preincubated with 1 mM serotonin. The heart

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and transcardiac rectum contained a largenumber of immunoreactive fibers and vari-cosities. Control sections of both rectum andheart showed no positive staining. In con-trast the ABRM displayed no specificstainining. The data suggest that serotoninis likely involved in the control of the heartand digestive tract as in other molluscs.Since this neurotransmitter can either beexcitatory or inhibitory in other molluscs, wewill need to perform bioassays with thesetissues to establish its role. We are currentlyexamining other zebra mussel tissues forthe presence of serotonin.

P2.23KRAUS-EPLEY, K.E.*, MOORE, P.A.,Bowling Green State University. The effectsof antennal lesions on orientation behaviorof the crayfish, orconectes rusticus.

Numerous animals use chemical cueswithin their environments to execute vari-ous behaviors. One of these behaviors isorientation to a food source. Crayfish, in par-ticular, can orient to food sources under anumber of different conditions. It has notbeen determined, however, if and how theseanimals with complete or partial impairmentof their chemosensory appendages can suc-cessfully locate a food source. To determinethe effects of impairment, the orientation pat-terns of crayfish with various degrees of an-tennal lesions were examined. Analysis ofresults confirmed that crayfish successfullylocate distant food sources using chemot-axis and must have both antennae to do so.It appears that crayfish use the spatial infor-mation from bilateral sampling to success-fully orient. Animals using both antennaeexhibited increased walking speed andspeed to source, decreased heading angletowards the source, and a more linear paththan animals with the use of one or neitherantenna(e). It was also found that otherchemosensory appendages, includingchelae and walking legs, play a lesser rolein orientation than may have been previ-ously thought.

S8.8 KRENTZ, D., Walt Disney FeatureAnimation. Design of digitally animated char-acters: biological solutions for fantastic situ-ations.

Design of animals in animated filmsmust balance the needs to make thembelievable as organisms and interestingas characters that interact with a definedstoryline. Morphological construction for or-ganisms focuses initially on musculoskel-etal anatomy. Initial designs attempt to re-main as true to actual structure as pos-sible. Even the retention of correct posi-tioning of such small elements as the su-praorbital bones in certain dinosaurs wasa consideration in the recent film Dinosaur.Given that dinosaurian skeletal anatomyis well known for many taxa, this initial stepmay be fairly straightforward. Characterdesign proceeds until each can be repre-sented by orthographic drawings andthree-dimensional sculptures (maquettes)that guide animators through film produc-tion. In the case of predominantly digitallygenerated films such as Dinosaur, ap-proved orthographic drawings andmaquettes direct computer modelers, andcomputer animators produce the moving,on-screen characters. However, truth andfantasy are necessarily hybridized to sat-isfy the demands of story and productiondecisions. The most typical examples arewhen nonhuman characters speak or en-gage in other anthropomorphic behaviors.In these cases, the generation of fancifulbehaviors are often derived from basic bio-logical solutions. In the example of prog-nathous iguanodontids in the film Dino-saur, there was no true reptilian model forfacial expression. In this case, mamma-lian muscles of facial expression wereadapted from horses to provide a workingmodel for facial movement with reason-able proportions. Ultimately, animated filmsdo not necessarily remain true to animalphysiognomy at all times, but when theydepart from nature, problem-solving fornovel functional combinations frequentlyreturns to the kinds of solutions that “na-ture dictates.”

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P3.14KRENZ, J.G.*, HASELKORN, T.S.,BRODIE, E.D., III, BRODIE, E.D., JR.,JANZEN, F.J., Iowa State University, IowaState University, Indiana University, UtahState University, Iowa State University. Mo-lecular phylogeography of common gartersnakes (Thamnophis sirtalis) in westernNorth America.

Populations of the common garter snake(Thamnophis sirtalis) in western NorthAmerica that are found in the same range asthe coastally distributed rough-skinned newt(Taricha granulosa) display resistance to thepoisonous effects of the newtís tetrodotoxin(TTX), while common garter snake popula-tions outside of the range of the newt do notdisplay TTX resistance. In an effort to un-cover the evolutionary pattern of TTX resis-tance in the common garter snake, we col-lected 2218 nucleotides of mitochondrialDNA sequence data including completeND2, partial ND4, and partial cytochrome bgene sequences. Phylogenetic analysis ofthe data revealed at least two independentorigins of TTX resistance in the common gar-ter snake.

29.3 KRENZ, J.G.*, JANZEN, F.J., IowaState University. Turtle phylogeny: insightsfrom a nuclear gene.

Turtles have a long and successful evo-lutionary history, dating back over 200 mil-lion years. Relationships among many ex-tant turtle families remain unclear, despite alarge data set containing morphological char-acters as well as DNA sequences from themitochondrial cytochrome b and 12S ribo-somal DNA genes. DNA sequence data froma single copy nuclear gene, RAG-1, yieldsnew insights into turtle evolution. Results ofseparate analyses as well as total evidenceanalysis are discussed.

S7.5 KRISTENSEN, R.M., University ofCopenhagen. An introduction to Loricifera,Cycliophora, and Micrognathoza.

Adult loriciferans are bilaterally sym-metrical marine metazoans between 108-485 microns. The body is divided into fiveregions: mouth cone, head (introvert), neck,thorax and abdomen. The first description ofa loriciferan (Nanaloricus mysticus) was in1983 from specimens collected from shell

gravel off the coast of France. The fine struc-ture of the mouth cone, the introvert and thecircumenteric brain indicate that the phylumis related to Kinorhyncha and Priapulida. An-nulation of the flexible buccal tube, telescop-ing of the mouth cone and three rows ofplacoids in the triradiated pharynx bulb arefound only in Tardigrada and Loricifera, butmay be convergent. The marine Cycliophorais the most recently described animal phy-lum. Cycliophorans are bilateral acoelomatemetazoans with a well-differentiated cuticle.A single microscopic species (Symbionpandora) was described in 1995.Cycliophorans appear to be a new type ofepibiont with a very complex life-cycle livingmainly on the setae of the mouthparts of sev-eral lobster species. Cycliophorans havesome similarities to sessile rotifers but areconsidered related to entoprocts although amolecular study suggests that cycliophoranscould be related to Syndermata (Acantho-cephala + Rotifera). A new microscopicaschelminth-like animal, Limnognathiamaerski with complicated jaws was de-scribed in 2000. It was assigned to a newclass, Micrognathozoa within Gnathifera,which now includes Gnathostomulida,Micrognathozoa and Syndermata. The ul-trastructure of the jaw suggests homology tojaws of gnathostomulids and the rotiferanmastax. Limnognathia maerski has dorsalplates formed by an intercellular matrix as inRotifera and Acanthocephala, but ventrallythe epidermis is “naked” with a thinglycocalyx. The gross anatomy of the bodyconsists of a head, thorax and abdomen. Thelocomotory organ consists of two rows of cellswith cilia.

12.3 KROCHMAL, A.R.*, BAKKEN, G.S.,Indiana State University Evidence for the useof facial pits for behavioral thermoregulationin the western diamondback rattlesnakes(Crotalus atrox).

Pit vipers (Crotalinae) possess uniqueorgans, called facial pits, which can detectsubtle fluctuations in emitted thermal radia-tion. Facial pits are used for prey locationand strike direction, demonstrating that pitvipers can incorporate thermal informationinto their behavioral patterns. Though neverthoroughly investigated, such thermal infor-

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mation could play a significant role in thethermoregulatory behavior of pit vipers. Be-havioral thermoregulation can impact socialand foraging behaviors, increase predationrisk, and impart physiological costs. Locat-ing thermally favorable microsites efficientlywould minimize these constraints, and theability to do so should be favored by naturalselection. Emitted thermal radiation is a di-rect indicator of an object’s surface tempera-ture, and the ability to use it as a behavioralcue would allow pit vipers to efficiently de-tect thermally favorable microsites. There-fore, we hypothesized that pit vipers mightuse their sensitivity to emitted thermal radia-tion to locate thermally favorable micrositesfrom a distance. In preliminary Y-maze trials,snakes were able to locate thermally favor-able microsites more often than predictedby chance (p < 0.01, sign test). Thus, West-ern Diamondback Rattlesnakes (Crotalusatrox) may have the ability to use the ther-mal sense to locate thermally favorablemicrosites in the absence of other cues.

19.4 KUFFNER, I.B., University of GuamMarine Laboratory, Mangilao. Effects of ul-traviolet radiation and water motion on thereef coral Porites compressa: a transplanta-tion experiment.

Ultraviolet radiation (UVR, 280 - 400 nm)is an important ecological variable affectingcoral reef organisms, but UVR effects maybe influenced by other factors such as watermotion. In this study, the effects of ambientUVR and water motion on several physi-ological parameters of the reef coral Poritescompressa were investigated in a factorialtransplantation experiment. Branches fromnine different colonies were transplantedfrom the windward side of Coconut Island(Kaneohe Bay, Hawaii) to a control area onthe windward side (ambient water motion)and to an area on the leeward side (lowwater motion). Transplanted corals wereplaced under UV-opaque or UV-transparentfilters fixed to the reef. Initially and at threeand six weeks, coral branches wereweighed to determine calcification rate, andtissues were extracted to analyze photosyn-thetic pigments and the concentration of theUV-absorbing compounds, mycosporine-like amino acids (MAAs) via HPLC. When

UVR was screened from the corals’ envi-ronment, total MAA concentration decreasedby 33 % over six weeks. The presence ofUVR resulted in higher concentrations ofMAAs in UVR-exposed colonies comparedto colonies shielded from UVR. However,UVR-exposed corals moved to low water mo-tion decreased MAAs while UVR-exposedcorals moved to the control area retainedinitial levels. Photosynthetic pigments andcalcification rate were also significantly lowerin corals moved to low water motion. Therewas no UVR effect on photosynthetic pig-ments or calcification rate. This study pro-vides evidence that water motion is impor-tant for the maintenance of MAAs. However,there were interesting colony-specific pat-terns in MAA composition in response to theUVR treatment, indicating a genetic (host,zooxanthellae or both) component to UVRresistance.

25.6 LABARBERA, M. University of Chi-cago, Chicago, IL. Physical constraints inscallop swimming: take-off and swimmingmechanics.

Take-off from the substrate and swimmingwere recorded for the cold-temperate scal-lops Chlamys hastata (N=10), C. rubida(N=22), and Crassodoma gigantea (N=7)and the warm-temperate Argopectenirradians (N=43) using high speed video.The Chlamys species and Argopecten swimthroughout their lives, but Crassodomaswims only as juveniles; adults are cementedto the substrate. Video recordings were ana-lyzed to determine clap frequency, instanta-neous accelerations, and average speed.Scallops ranged in height from 5-65 mm forthe Chlamys species, 5-57 mm forArgopecten, and 26-45 mm for C. gigantea.Peak acceleration for all species was ap-proximately 0.5 ms-2; the largest and small-est individuals exhibited lower accelerationsthan intermediate-sized animals. Averageswimming speed (integrated along theanimal’s path) ranged from 10-40 cm/s.Larger animals achieved higher absoluteswimming speeds, but relative speeds (shellheights/sec) were maximal in the smallestanimals and declined linearly with increas-ing shell size. For all species, clap frequencywas a linear function of shell height; C.

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gigantea was indistinguishable from theother species during its byssally-attachedphase. Using published data for an addi-tional seven species of scallops, a singlefunction describes the relationship betweenshell height and clap frequency for all scal-lops, independent of phylogenetic relation-ships or environmental temperature. Thesedata are the first measurements of accelera-tion during jetting for any scallop and thefirst quantitative description of swimming injuvenile Crassodoma.

43.4 LADUC, T.J., University of Texas, Aus-tin; Texas Memorial Museum. Effects of bodysize on the predatory strike of the westerndiamondback rattlesnake (Crotalus atrox).

Changes in body size can be of particu-lar importance to feeding mechanics, yet littleinformation is available for allometric effectson terrestrial vertebrate feeding systems.The predatory strike of rattlesnakes, alongwith the great range of sizes exhibited bothontogenetically and interspecifically withinthis taxon, allows us to test whether changesin body size constrain the evolution of strikeperformance. Multiple strikes from ten west-ern diamondback rattlesnakes (Crotalusatrox) of varying sizes were filmed using ahigh-speed video camera (1000 fps), and adiversity of speed, distance, and behavioralparameters were analyzed. Intraspecifically,smaller snakes are predicted to have highermaximum accelerations based on the allom-etry of force generation and body propor-tions. However, body scaling data indicatedeviations from isometry in several bodymeasurements, such as head volume.

64.4 LAMBERT, J.D., NAGY, L.M., Univer-sity of Arizona. The role of MAPK signalingin patterning mollusc embryos.

Classical experiments performed on theembryo of the mollusc Ilyanassa obsoletademonstrate that the 3D macromere acts asan embryonic organizer, by signaling toother cells and inducing them to assume thecorrect pattern of cell fates. We have discov-ered that MAP Kinase (MAPK) signaling isactivated in the cells which require the sig-nal from 3D for normal differentiation. Pre-venting specification of the D quadrant lin-eage by removing the polar lobe disrupts

the pattern of MAPK activation, as does ab-lation of the 3D macromere itself. BlockingMAPK activation with the MAPKK inhibitorU0126 produces larvae which differentiatethe same limited complement of tissues asD quadrant deletions. Our results suggestthat the MAPK signaling cascade transducesthe inductive signal from 3D and specifiescell fate among the cells that receive the sig-nal. We also report the pattern of MAPK ac-tivation in other mollusc embryos, and dis-cuss the implications for the evolution of axialpatterning in this group.

60.4 LAMMERS, A.R., Ohio University Theeffects of incline and branch diameter onthe kinematics of arboreal locomotion.

It is likely that the common ancestor ofMammalia was small, quadrupedal, andscansorial. To better understand the kine-matics of arboreal locomotion in a primitive,scansorial mammal, I examined the effectsof branch angle and diameter on limb pos-ture, speed, gait and duty factor in the SouthAmerican possum Monodelphis domestica.Animals were filmed (250 f/s) walking up ar-tificial branches of different angles and di-ameters. Kinematic data were then mea-sured from the videos. Data indicate thatbranch angle (up to 45 degrees) has littleeffect on limb kinematics for these smallmammals. These results may explain whyTaylor et al. (1972, Science 178:1096) foundthat low substrate incline had less metaboliceffect on running mice compared to chim-panzees; furthermore, Vilensky et al. (1994,J. Hum. Evol. 28:375) found kinematic differ-ences with substrate incline in squirrel mon-keys. Therefore, as mammals become largerover evolutionary time, the effects of gravityand mass appear to cause changes in ar-boreal kinematics.

10.5 LANCASTER, W.C.*, WARD, S.,JONES, G., SPEAKMAN, J.R., Pikeville Col-lege School of Osteopathic Medicine, Uni-versity of St. Andrews, U.K, University ofBristol, U.K., University of Aberdeen, U.K. En-ergetics of biosonar vocalization in station-ary insectivorous bats.

Previous studies show a linkage be-tween flight and production of biosonar callsin bats. Microchiropteran bats also emit a

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wide variety of calls while at rest includingbiosonar calls of high intensity in some spe-cies. The propensity of bats to make echolo-cation calls at rest is variable and studiessuggest that energetic constraints may un-derlie this variability in behavior. We mea-sured the energetic expenditure associatedwith biosonar call production at rest in fivespecies of insectivorous bats using respirom-etry. The species use distinct modes of for-aging and this is reflected in call structure,intensity and phrasing. Oxygen consump-tion associated with vocalization increasedwith rate of call production. The slope of theplot of watts vs. call rate gives mean cost percall. This cost was greatest in Eptesicusserotinus at 0.22 J/call, was 0.19 in Myotismyotis, 0.12 in Pipistrellus pipistrellus, 0.03in Pteronotus parnellii and in Rhinolophusferrumequinum was 0.03 J/call. Costs percall were inversely related to the species’propensity to produce calls at rest. In threespecies where data are available, energyflux density of calls averaged 7.63 x 10-7J/m2 in R. ferrumequinum, 3.69 x 10-7 in P.pipistrellus and 2.30 x 10-7 in M. myotis. Inthe other species, P. parnellii has calls of simi-lar intensity and duty cycle to R.ferrumequinum and E. serotinus is similar toPipistrellus. Bats that produce the most vo-cal energy at rest are expending the leastamount of energy in doing so. We suggestthat these species have behavioral and mor-phological adaptations to reduce the costand increase the efficiency of producingbiosonar calls at rest. Funded by BBSRC(UK)1/S04245.

28.5 LANDRY, S.O., SUNY-Binghamton.The carnivore skull as a clinker-built hull.

Ancient Mediterranean ships’ hulls were“carvel built”, that is, the strakes (longitudi-nal planks of the hull) were fastened to eachother edge-to-edge by mortise and tenon,whereas the Vikings and other sailors of thenorthern seas, used “clinker built” hulls, inwhich the strakes overlapped each otherlaterally and were held together by clenchnails. It is thought that clinker built hulls arebetter able to resist the poundidng of therough northern seas. This may be becausethe overlapping planks can, to a small de-gree, ride up over each other without start-

ing (springing leaks.) Specifically, clinkerbuilt hulls appear better able to resist tor-sion. In carnivores, canine teeth are usedasymmetrically; that is, stress is predomi-nantly on one side producing torsion at therear end of the skull. Overlap of bones isquite common in mammals, but a deep,scarfed overlap of the squamosal over theparietal is found in carnivores, suggestingthat skull structure may parallel clinker con-struction, for the same mechanical reason.In addtion, the ossified tentorium cerebelliof carnivores may serve the same purposeas a rib in a ship’s hull in resisting torsionaldeformation.

P3.71A LANDYS, M.M., RAMENOF-SKY,M., PIERSMA, T., WINGFIELD, J.C., Univer-sity of Washington, Seattle, University ofWashington, Seattle, Netherlands Inst. of SeaRes., The Netherlands, University of Wash-ington, Seattle. Regulation of potentially con-flicting behavior and physiology during mi-gration.

The avian stage of migration is com-prised of distinct sub-stages within whichpotentially conflicting issues are at work:energy mobilization during flight, versusenergy storage during fueling. Therefore,precise control of behavior and physiologyduring different sub-stages is critical for effi-cient travel. Corticosterone, the glucocorti-coid found in birds, regulates metabolismand feeding, and may participate in the con-trol of migration. I examined the pattern ofcorticosterone secretion across different mi-gratory sub-stages in a long-distance shore-bird migrant. Levels of corticosterone wereelevated prior to and during migratory flightas compared to the refueling sub-stage, sug-gesting that corticosterone may promotebehavioral and physiological process typi-cal of departure and flight. Because baselinelevels of corticosterone were far below thoseduring capture, I suggest that corticosteronemay play a role during migration that is dis-tinct from stress effects. To explore the be-havioral role of corticosterone during migra-tion, I experimentally manipulated circulat-ing levels in captive migrants and monitoredresulting differences in behavior. Birds withlow levels of corticosterone tended to inves-tigate the mudflat and cage floor less than

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did controls. In addition, birds with low corti-costerone titers tended to decrease bodymass, even though feeding behaviors werenot affected. These results suggest that anelevated level of corticosterone promotesawareness of the environment and assistsin the maintenance of the body mass peaktypical of departure. On-going studies willverify these data and clarify the physiologi-cal role that corticosterone may play duringmigration.

S3.8 LANGENBACH, G.E.J., AcademicCentre for Dentistry Amsterdam, The Neth-erlands. Mammalian feeding.

In mammals, basic symmetrical foodtransport cycles have been described forlapping and soft food ingestion. To increasechewing efficiency a unilateral occlusal mo-tion has been evolved replacing the slowclosing phase in the basic cycle. This powerstroke is preceded by fast opening and clos-ing phases increasing the gape. Jaw open-ing is produced by action of the digastricsand hyoidal muscles, often supported byactivity of the lateral pterygoid muscles. Ac-tivity of these muscles is usually asymmet-ric, moving the jaw to the working side. Therelative uniformity of the mammalian jawcloser motor patterns is striking. Neverthe-less, several specialisms, clearly differentfrom the primitive mammalian asymmetricmasticatory motor pattern, can be distin-guished. Weijs (1994) proposed tocategorise these into four groups, the carni-vore symmetric, the rodent symmetric, thetransverse and the alternate patterns. In con-trast to the relative uniformity in motor pat-terns, the anatomical diversity of jaw sys-tems is impressive and probably reflects theadaptation to diet. Mostly in the last decade,this diet influence has been investigated.With tougher foods, an increase in the clos-ing activity has been found, in combinationwith a prolonged duration and often ex-tended transverse dimension of the powerstroke. Data suggest that the individual mas-ticatory cycles are largely shaped by sen-sory feedback. Also the suckling food intakepreceding mastication has been a point ofinterest. It seems that mammals use expres-sion and suction mechanisms to collect themilk. Both motor patterns resemble that of

mastication, suggesting that transition couldbe gradual. Recently, dynamic computer 3D-modeling has emerged as an analytical tool.The approach has the potential to help ex-plain how structure and function interact, andto elucidate the existence of different feed-ing motor patterns.

66.6 LANNOO, M.J.*, NANJAPPA, P.,BLACKBURN, L.M., Muncie Center for Medi-cal Education, Indiana University, Ball StateUniversity, Muncie, IN, Ball State University,Muncie, IN. What amphibian malformationstell us about causes.

Amphibian malformations in northernand eastern regions of North America havegenerated considerable attention from boththe general public and the scientific com-munity. Common malformations of ranid frogscollected by the Minnesota Pollution Con-trol Agency include missing limbs (ectrome-lia) and multiple limbs (polymelia). Despitethe co-occurrence of both types of malfor-mations among animals in any given hotspot, and the disparate locations of hotspots, some researchers argue that discretefactors cause different malformations (Kai-ser, 1998, Science, 278:2051-2052; Souder,2000, A Plague of Frogs, Hyperion Press).Gross and radiographic analyses show thattwo unusual features — spongiform boneand dorsal pigment abnormalities — appearin a subset (74%) of malformed ranids. Suchbone and pigment abnormalities are diffi-cult (bone) or impossible (pigment) to detectin cleared and stained animals. The pres-ence of spongiform bone and dorsal pig-ment malformations proximal to the missinglimb region strongly argue against preda-tion being the main cause of ectromelia.Spongiform bone and pigment malforma-tions also appear in polymelic animals. Thepresence of these abnormalities in both ec-tromelic and polymelic animals argues twothings: 1) a shared cause, manifested differ-ently depending perhaps on dosage orvariations in exposure; and 2) the rejectionof hypothesized causes that do not producethese malformations.

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42.1 LAPPIN, A.K.*, NISHIKAWA, K.C.,PIEROTTI, D.J., Northern Arizona Univer-sity, Flagstaff. Isometric contractile propertiesof anuran jaw muscles and their relation-ship to feeding mechanics.

All terrestrial frogs examined to date usetongue prehension to capture prey. Threecategories of feeding behavior have beenidentified in frogs with respect to tongue per-formance during prey capture. Tongue per-formance characteristics that vary markedlyamong taxa in the different behavioral cat-egories include percent elongation of thetongue, and maximum tongue velocity andacceleration during protraction. Previousresearch on the isometric contractile prop-erties of the tongue protractor and retractormuscles did not reveal functional differencesthat explain this variation in tongue perfor-mance. One factor that may cause differencesin tongue performance is the transmissionof inertial forces via jaw movements duringfeeding. Jaw opening velocity and accelera-tion is greater in species that exhibit greaterelongation, velocity, and acceleration of thetongue during its protraction. As a first steptowards elucidating the role of jaw move-ments in effecting tongue protraction, wecompare jaw muscle contractile propertiesof representatives of two feeding behaviorcategories. In situ experiments were per-formed in which muscle origins were left in-tact. Removal of a lower jaw section isolatedmuscle insertions, which were attached to aforce transducer. Via direct muscle stimula-tion, we quantified the length-tension curve,contraction time, half-relaxation time, stimu-lus frequency-tension curve, and fatigabilityof each muscle. With these data, we test thehypothesis that jaw muscles of species withfaster, more greatly elongating tongues haveshorter contraction times and greater forceproduction.

P3.49LARSON, E.T.*, WINBERG, S.,BROWN, C.L., LARHAMMAR, D., UppsalaUniversity, Uppsala University, Hawaii Insti-tute of Marine Biology, Uppsala University.Differences in distribution of NPY and NPYreceptors in a sex changing fish.

Saddleback wrasse (Thalassomaduperrey) a protogynous sex-changing fishfrom the Hawaiian Islands, have behavioral

differences based on sex and social roles.Dominant, territorial terminal phase (TP)males can develop from either females orinitial phase (IP) males. Previous work indi-cates that neuropeptide Y (NPY) can stimu-late release of gonadotropins in fishes. Ad-ditionally, NPY has been show to stimulatesex reversal in the congener T. bifasciatum.NPY and peptide YY (PYY) are closely re-lated peptides that bind to the same recep-tors. Fish were collected from reefs duringtime of daily mating. PYY was labeled with125I and applied to brain sections to deter-mine receptor distribution. Anti-NPY was alsoapplied to sections to determine peptide dis-tribution. Females had receptor binding inthe dosomedial zone. TP males had recep-tor binding in hypothalamic, preoptic area(POA) and tuberal nucleus. All three pheno-types had receptor binding in optic tectum(OT). Distribution of NPY-like immunoreac-tivity (NPY-LI) occurred in the same regionsas receptor binding. The fact that NPY-LIand receptors are found in OT of all fish isprobably related to vision. The differencesin phenotypes suggests that in this speciesNPY affects regulation of sex or sex roles. T.duperrey demonstrates sexual plasticity viaprotogyny. NPY could play a role in main-taining the sexual status of individuals in thissystem when social cues inducing sex re-versal are absent. The presence of NPY-LIin the POA of TP males corresponds withearlier results in T. bifasciatum indicating thatTP males have greater GnRHir in POA. Thissuggests that NPY plays a role in mainte-nance of sexual status of TP males, likely viacontrol of GnRH.

67.2 LARSON, P., Ohio University.Chondrocranial development in larval Ranasylvatica (Anura: Ranidae): a morphometricanalysis of cranial allometry and ontogeneticshape change.

This study provides baseline quantitativedata on the morphological development ofthe chondrocranium in a larval anuran. Bothlinear and geometric morphometric meth-ods are used to quantitatively analyze sizerelated shape change in a complete devel-opmental series (n = 73) of larvae of the woodfrog, Rana sylvatica. The null hypothesis ofisometry was rejected in all geometric mor-

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phometric and most linear morphometricanalyses. Reduced major axis regressionsof 11 linear chondrocranial measurementson size indicate a mixture of allometric andisometric scaling. Measurements in the oticand oral regions tend to scale with negativeallometry and those associated with thepalatoquadrate and muscular process scalewith isometry or positive allometry. Geomet-ric morphometric analyses, based on a setof 11 chondrocranial landmarks, include lin-ear regression of relative warp scores andmultivariate regression of partial warp scoresand uniform components on log centroidsize. Results indicate that body size explainsabout one quarter to one third of the totalshape variation found in the sample. Areasof regional shape transformation (e.g., oticregion, trabecular horns) are identified bythin-plate spline deformation grids and areconcordant with linear morphometric results.These results indicate that the anuran chon-drocranium is not a static structure duringthe pre-metamorphic stage with allometricpatterns generally following scaling predic-tions for tetrapod cranial development.

2.2 LAURITZEN, D.V.*, HERTEL, F., GOR-DON, M.S., University of California, Los An-geles, California State University, Northridge,University of California, Los Angeles. Kine-matics of salmon leaping up waterfalls.

Fish ladders have been used for hun-dreds of years to help migratory fishes moveupstream past human-made obstacles suchas dams. The designs of these ladders ap-pear to have given little consideration to thebehaviors and leaping abilities of the fishesthey are supposed to help. These inadequatedesigns seem partly a result of the paucity ofinformation on the behavior and biomechan-ics of fishes as they leap. We hope to inte-grate biological considerations with the de-sign and construction of fish ladders by un-derstanding the preferences, capacities andlimitations of wild fishes leaping up naturalstream obstacles. We analyzed aspects ofthe biomechanics of leaping in sockeyesalmon as they passed two natural water-falls during their spawning migration. Videorecordings were used to track the fish asthey traveled through the air and kinematicparameters of individual leaps were quanti-

fied. Stream characteristics were also mea-sured in the vicinity of the leaping fish. Theseresults are summarized along with calcu-lated theoretical parameter values for suc-cessful leaps. We plan to conduct future stud-ies correlating the hydrology downstream ofwaterfalls with leaping salmonid kinemat-ics, both underwater and in air. These stud-ies will experimentally investigate the pref-erences of migrating salmonids at streamobstructions. These results along with thetheoretical model describing successfulleaps may be used in the development offish ladders to help maintain a natural pas-sage rate of fishes up streams that containhuman made obstacles. This study wasfunded by the Centers for Water and Wild-land Resources project number W-928 andthe UC Energy Science and TechnologyProgram.

P2.47LAWRENCE, K.A., STRANGE, R.M.,Southeast Missouri State University. Allom-etric neuroanatomy among percids: corre-lation with adaptive trends?

Adaptation to small headwater streamsand a concomitant reduction in overall sizeis a major evolutionary trend in percid fishes.Changes in behavior, such as habitat pref-erences and life history attributes, are oftenlinked with changes in the proportionatesizes of corresponding regions of the brain.We examined the neuroanatomy amongprimitive percids (Perca and Stizostedion),primitive darters (Percina spp.), and morespecialized darters (Etheostoma spp.) forevidence of simple scaling effects, correla-tion with adaptive changes in behavior, andphylogenetic legacy. A negative allometricrelationship exists between body mass andbrain mass in percids, indicating that dart-ers have proportionately larger brain massthan either Perca or Stizostedion. This maybe a scaling effect. Changes in cerebellumand optic lobes are isometric. A positive al-lometric relationship exists between both thecerebellum and optic lobes and the olfac-tory regions. Differing proportions amongbrain regions in percids may prove to beadaptive and not a phylogenetic effect if itcan be shown that darters rely more on vi-sion and agility in foraging and avoidingpredators than do Perca or Stizostedion.

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P3.40LAYNE, J. R. JR., KUHARSKY, D.K.,Slippery Rock University, PA, University ofPittsburgh, PA. Physiological consequencesof supercooling and freezing for overwinter-ing insects.

Freeze tolerance and enhanced super-cooling ability (freeze avoidance) are dis-tinct adaptations in insects facilitating sur-vival of subfreezing temperatures. It hasbeen suggested that freeze tolerance hasadvantages over freeze avoidance with re-spect to certain aspects of insect ecophysi-ology. Third instars of the goldenrod gall fly(Eurosta solidaginis Fitch) were kept eitherfrozen or supercooled at -5 C for 10 weeks.Supercooled larvae lost 26% of their wetweight (-15.2 mg) and frozen larvae lost 14%of wet weight (-8.3 mg), mostly as a result ofwater loss during the treatments. Moreover,although supercooled larvae lost more wa-ter than did frozen larvae (-13.5 mg vs. -7.9mg), lipid content was stable throughout bothtreatments (approximately 10 mg per larva).Freeze-treated larvae were more likely tosurvive to pupariation (92% vs. 65%) andadult emergence (73% vs. 50%) than weresupercool-exposed larvae. This insect spe-cies copes better with prolonged freezingthan it endures prolonged supercooling.However, it remains to be clarified whetheror not this effect can be attributed to differ-ences in water retention.

P1.39LEE, C.E.*, PIERMARINI, P., REID, N.,University of Wisconsin, Madison, Univer-sity of Florida, Gainesville, University ofFlorida, Gainesville. Independent invasionsof fresh water: low-salinity tolerance andactivity and expression of Na,K-ATPase inlineages of the copepod Eurytemora spp.

The invasion of fresh water has occurredat least eight times independently in the sib-ling species complex Eurytemora affinis. Weinvestigated the osmoregulatory role of anion-pumping enzyme, Na, K-ATPase, in in-vasive and non-invasive lineages of E. affinisand in a non-invasive congener E.americana. We measured enzyme activityand expression at salinities ranging from0.25 to 25PSU. We also measured devel-opment time and survival in response tosalinity. At low salinities, survival declined,development time increased, and activity of

Na, K-ATPase increased by about 1.5 foldfor E. affinis. In contrast, for E. americana,Na, K-ATPase activity declined with salinityand survival was 0% at the lowest salinities.A positive correlation between Na, K-ATPaseactivity and survival at lower salinities sug-gests that this enzyme plays a role in fresh-water survival. However, the modest 1.5-fold increase in enzyme activity is unlikely toaccount for the required ion uptake.Immunostaining for Na,K-ATPase was local-ized to the ventral nerve cord, and did notappear to vary among populations, species,or salinities. Moreover, we were unable tofind a distinct epithelial-based organ or glandthat could potentially function for ion excre-tion or ion absorption. Our results suggestthat Na,K-ATPase may not be an importantion regulatory enzyme for maintaininghemolymph concentration in copepods in-vading low salinities, unlike the scenario as-sumed for most invertebrates.

21.1 LEE, D. V., University of Utah, Salt LakeCity. Relating limb geometry to ground reac-tion force in running quadrupeds: a designfor stability?

A defining characteristic of legged loco-motion is forward movement of the body overthe feet, which remain more-or-less fixedwith respect to the ground. This mandatesthat, in quadrupeds, the limbs retract abouttheir proximal joints (i.e., hip or shoulder)during the entire stance. I used a simple,planar model to investigate the mechanicalconsequences of this kinematic constraint.The model consisted of a rigid body and twomassless limbs (a fore- and hindlimb). Theproximal segments were joined to distalportions of the limbs by rotational springsand were oriented either anteriorly or poste-riorly. The distal portions acted as compres-sion springs. Two basic assumptions weremade in the simulation: 1) limb excursionsare symmetrical with respect to a transverseplane through the proximal joint, and 2) thelimbs retract with a constant angular veloc-ity that produces no net acceleration or de-celeration during stance. Given these neu-tral criteria, proximal segment orientationwas found to produce substantial directionalbiases in ground reaction force during simu-lated trotting. A knee-forward, elbow-back

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geometry emulated the hindlimb accelera-tion bias and forelimb deceleration bias ob-served in trotting quadrupeds. This limb ge-ometry, which is common to nearly all quad-rupeds, may provide intrinsic mechanicalstability during running.

P3.73LEE, K.J.*, WATSON, R.D., Universityof Alabama at Birmingham. Production ofantipeptide antibodies for detection of crus-tacean molt-inhibiting hormone.

In crustaceans, the synthesis of steroidmolting hormones, ecdysteroids, is nega-tively regulated by a neuropeptide molt-in-hibiting hormone (MIH). Amino acid se-quence data place MIH in the crustaceanhyperglycemic hormone (CHH) family. Aspart of our studies of the control of growthand molting in blue crabs (Callinectessapidus), we have generated antipeptide an-tibodies for detection of MIH. Using GCG(University of Wisconsin) sequence analy-sis software programs, two regions of theblue crab MIH peptide were selected for an-tibody production. These fragments wereselected using multiple alignment and pep-tide structure programs that predicted re-gions of MIH having high surface probabil-ity, flexibility and antigenicity, but which werenot highly conserved between MIH and othermembers of the CHH family. The two 10-mer peptides were commercially synthesizedand used to generate polyclonal antisera inrabbits. The binding properties of the antis-era were characterized by immunocy-tochemistry (ICC) and Western blot. Thinsection ICC showed specific immunoreac-tivity in the X-organ/sinus gland complex ofeyestalk neural ganglia with both antisera.Western blot analysis revealed that bothantisera also bound to proteins of the pre-dicted size in blue crab sinus gland extractsand cell lysates containing recombinant MIHprotein. We anticipate that these antipeptideantibodies will be useful for developing animmunoassay for quantification of MIH inhemolymph. Supported by MS/AL Sea Grantand NSF.

P3.69LEONARD, J.B.K.*, PLISETSKAYA,E.M., SILVERSTEIN, J.T., Northern MichiganUniversity, Marquette, MI, University of Wash-ington, Seattle, WA, USDA/ARS-CGRU,

Stoneville, MS. Effect of season and age onthe hypothalamic neuropeptide Y mRNA re-sponse to fasting in channel catfish.

While food intake is likely controlled by avariety of interacting neuroendocrine factors,neuropeptide Y (NPY) has repeatedly beenimplicated in this complex behavior. NPY’saffects on food intake in fish are likely local-ized to the hypothalamus and preoptic area.We investigated how hypothalamic NPYmRNA responds to fasting and how it differsbetween strains of fish known to grow differ-ently. Fish of two strains of channel catfish(Ictalurus punctatus; Norris and USDA 103)were kept at constant 26oC and 12:12 LL:DDphotoperiod from December (~ 7 g fish mass)until June and subjected to monthly, 1-week,fasting challenges. During the study, USDA103s grew significantly faster than Norris.The expected elevation in NPY mRNA didoccur in response to fasting in catfish, al-though this response was not demonstratedthroughout the study. During spring (Apr, fish~100 g), there was an elevation of hypotha-lamic NPY mRNA in fasted fish. In winter(Dec-Feb) and during the summer (May-June), there was no suggestion of this pat-tern. Plasma insulin levels also followed thisgeneral pattern of the maximum responseto fasting (a decrease in this case) occurringin the spring. Our results suggest that 1)hypothalamically-produced NPY is impor-tant in the neural response to fasting, butthat other areas of the brain are likely in-volved 2) the response of channel catfish toa fast varies with season and/or size 3) thereare likely differences in the endocrine con-trol of feeding between different strains ofcatfish. This work was supported in part byNSF grant #IBN-9722830.

P3.67LEONARD, C.M.*, MAYS, L.,BRANDONI, C., MONTES,C., MENON, J.,William Paterson University, Wayne NJ. Therole of nitric oxide in amphibian develop-ment.

The role of nitric oxide (NO), a free radi-cal, as a novel intercellular signal moleculein embryonic development of several organ-isms has been well documented. In addi-tion, NO has been also shown to be involvedin remodeling of the spinal cord and thyrox-ine induced tail regression in anuran tad-

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poles. In this study, the distribution ofNADPH- diaphorase (NADPH-d) activitywas studied in Xenopus laevis tadpolesduring embryonic and post-embryonic de-velopment by the histochemical reaction ofNADPH-diaphorase that indicates the pres-ence of nitric oxide synthase (NOS), the en-zyme responsible for nitric oxide production.Developmental stages were designated ac-cording to Nieuwkoop and Faber, (1967). Thehighest activity appeared at stage 37/38 andby stage 46/47, NADPH-d activity was widelydistributed in brain especially in olfactorylobes, cerebral hemispheres and cerebel-lum which could be due to development ofneuronal connectivities and synaptic plas-ticity. By the time tadpoles reached stage 52,there was complete lack of NADPH-d activ-ity in the brain. In this study we also show theenhancement of NADPH-d staining in re-sponse to retinol and retinol/thyroxine treat-ment in vitro. At the molecular level, the lev-els of mRNA for NOS increased significantlyin response to these treatments. In conclu-sion, we propose a role for NO as a hor-mone-sensitive trigger, beginning the com-plicated cascade of events that lead to theremodeling of brain and regression of tis-sues such as tail during amphibian meta-morphosis. The presence and distribution ofthis enzyme in evolutionarily distant animalsfrom mammals adds information about therole of nitric oxide in development.

11.2 LERMAN, D.N.*, BETTENCOURT,B.R., YI, C.H., KIM, I., FEDER, M.E., Univer-sity of Chicago. Response of an Hsp70 genecluster to laboratory and natural selection inDrosophila melanogaster.

We investigated whether polymorphismsat the 87A7 hsp70 cluster, which includes 2of the 5 genes encoding the inducible mo-lecular chaperone/heat-shock proteinHsp70, respond to natural and laboratorythermal selection in Drosophila populations.Our principal foci were morphs originally re-ported by Goldschmidt-Clermont (1980,Nucleic Acids Res. 8) as clones 122 and56H8, and detectable by PCR and RFLPanalysis. Allele frequencies covaried withevolution temperature in Drosophilamelanogaster lines that have been cultured

at different temperatures for more than 20years and that differ in Hsp70 expressionand inducible thermotolerance. Replicatelines evolving at 28ƒC fixed the 56H8-typemorph, while those evolving at 18ƒC and25ƒC fixed the alternative allele. Popula-tions selected for low knockdown tempera-ture (Gilchrist & Huey, 1999, Heredity 83)also differed in 56H8-type allele frequen-cies from the control and high selected popu-lations. To test if hsp70 allele frequenciescovaries with temperature in natural Droso-phila populations, we screened flies from“Evolution Canyon,” a small canyon in Israel(200 m wide at base) with north- and south-facing slopes (NFS and SFS, respectively).Allele frequencies in the NFS differed sig-nificantly from those in the SFS. Allele fre-quencies also covaried with collection lati-tude in Australian Drosophila populationsfrom tropical to temperate (gift of Ary A.Hoffmann). These results suggest that alle-les at the hsp70 87A7 cluster respond to ther-mal selection in both natural and laboratoryenvironments. The functional significanceof the alleles themselves (or of sequenceslinked to these markers) remains to be de-termined. Supported by NSF97-23298, 99-86158, BSF98-00443, and HHMI.

S1.6 LEWIS, E.R. R., NARINS, P.M.*,University of California, Berkeley, Universityof California, Los Angeles. Do white-lippedfrogs use seismic signals for intraspecificcommunication?

In the inner ear of a modern frog, the vol-ume occupied by the saccule is approxi-mately equal to that occupied by all of theseven other sensory endorgans taken to-gether. Unlike that of any other terrestrialvertebrate, the sensory surface (macula) ofthe modern-frog saccule is detached fromthe wall of the otic capsule and suspendedon a pool of periotic fluid. The sensory hairbundles are those of an acoustic sensorrather than a sensor of slow motion or ori-entation. The primary afferent axons are re-sponsive to both airborne sound and sub-strate vibration— being exquisitely sensitiveto the latter, especially in the dorsoventralplane. Their spikes are phase-locked to alinearly-filtered version of the stimulus wave-

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form. The filter dynamics are remarkablycomplex, providing excellent temporal reso-lution, passing energy in the frequencyrange (10-150 Hz) appropriate for local seis-mic signals in the ground, and strongly re-jecting energy in the frequency range (be-low 10 Hz) occupied by typical microseis-mic background noise. For stimuli in themiddle of the filter pass band, many indi-vidual axons exhibit conspicuous responsesto vibrational accelerations of the order of0.5 x 10-6g. In the field, the calling behavioroften reflects this sensitivity, even very gentlefootfalls producing a local area of silenceamong a chorus of male frogs. The airbornecalls of the males of one species,Leptodactylus albilabris, often are accom-panied by a strong seismic componentwhose spectrum lies in the middle of thesaccular-filter passband. Hoping to obtaindefinitive evidence of involvement of thiscomponent in male-male communication,we undertook what has evolved into a longseries of behavioral studies in the field.These have centered about a timing gap inthe male frog’s advertisement call, producedin response to calls of conspecic males.

S12.2LEWIS, S.A., University Texas Medi-cal Branch. Extracellular modulation of epi-thelial permeability.

One of the primary functions of an epi-thelium is to act as a barrier to the move-ment of substances between the lumen ofthe epithelium and the blood. Loss of epi-thelial barrier function due to cell death canlead to a loss of homeostasis and result indeath of the organism. Proteins associatedwith eosinophils, certain bacteria and presentin human semen have been demonstratedto be toxic to mammalian epithelial cells. Theeosinophil proteins are major basic proteinand eosinophil peroxidase, the bacterialprotein is polymyxin B and the proteins foundin semen are histones and protamine. Aproperty shared by these proteins is a highdensity (15-80%) of positively charged (ba-sic) amino acids. The effect of these proteinson the mammalian urinary bladder epithe-lium was studied using electrophysiologicaltechniques and confocal microscopy. It wasdemonstrated that these proteins cause cell

death by interacting and increase the ionpermebility of the cell membrane. Specifi-cally, we demonstrate that these proteins killepithelial cells by making their cell mem-brane leaky to both cations and anions, re-sulting in cell swelling and ultimately cell ly-sis. Additional sites of protein interaction havebeen suggested from studies utilizing con-focal microscopy. A model for epithelial celldeath by these positively charged proteinswill be discussed, and includes protein-membrane interaction, a voltage dependentstep, a recycling of membrane receptors andsites for divalent cation modulation.

P1.45LI, T.*, ROER, R.D., University of N.C.at Wilmington. Effect of salinity on gill Na+,K+-ATPase activity in juvenile and adultCallinectes sapidus.

Juvenile and adult blue crabs, Callinectessapidus, were collected from Cape FearRiver and acclimated in the laboratory fortwo weeks to either sea water (1050 mOsm)or dilute sea water (150 mOsm). Gills wereremoved from crabs, homogenized, andassayed biochemically for Na+, K+-ATPaseactivity. For adult crabs, individual anteriorand posterior gills were assayed individu-ally. For juveniles, anterior gills from indi-vidual crabs were pooled, as were posteriorgills. Both anterior and posterior gills werealso fixed and prepared for transmissionelectron and light microscopy. Gills from adultcrabs acclimated to sea water showed lowlevels of Na+, K+-ATPase activity, althoughthe posterior gills had twice that of anteriorgills. Juvenile crabs (<5g in weight) had en-zyme levels 11 times higher than those inthe anterior gills of adults and 7.5 timeshigher in posterior gills in sea water. Uponacclimation to 150 mOsm, adult anterior gillsdisplayed a 3-fold increase in Na+, K+-AT-Pase activity; posterior gills had a 4.3-foldincrease. In contrast, the anterior gills of ju-venile crabs had a 4.3-fold increase, whilethe posterior gills demonstrated an 11-foldincrease relative to sea water. Specific ac-tivity of Na+, K+-ATPase in juvenile gills at150 mOsm was 15 times and 19 times higherthan that of anterior and posterior gills ofadults, respectively. Preliminary microscopicexamination of anterior gills from 150 mOsm-

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acclimated juvenile crabs failed to revealmorphology typical of the transport epithe-lium of posterior gills.

2.3 LIAO, J., Harvard University. Locomo-tion in needlefish: anguilliform swimming withfins.

Anguilliform locomotion involves the un-dulation of an elongate body axis and is char-acteristic of a diverse array of vertebrates,ranging from fishes to salamanders and rep-tiles. The Atlantic needlefish, Strongyluramarina, is an elongate fish that displaysanguilliform locomotion and also possessesa typical percomorph fin arrangement. Whiledetailed body kinematics have been de-scribed for various anguilliform swimmers,no work has integrated the movement of theappendages during this mode of locomo-tion. In order to assess the role of the finsduring anguilliform locomotion, I swam fourneedlefish (mean total length L= 24cm)in aflow tank at eight speeds (0.25- 2.0 Ls-1) andcaptured simultaneous images of the ven-tral and posterior view using two synchro-nized high-speed video cameras. Fromthese images I analyzed the kinematics ofthe body, pectoral fins, dorsal and anal fins,and caudal fin. Preliminary data show thatat the lowest speed the pectoral fins oscil-late at 3.7 Hz, while during the highest speedthe pectoral fins are held flush against thebody. The dorsal and anal fins move syn-chronously and are out of phase with bodyundulations at the lower speeds, leading thebody during lateral excursions in a mannerthat suggests active control. At the lowestspeed the tail oscillates at 2.8 Hz, while atthe highest speed the tail oscillates at 6.0Hz. A large (133%) increase in the maxi-mum lateral tail displacement is observedacross the range of speeds (atypical of te-leost locomotion), from 2.4% L at the lowestspeed to 5.6% L at the highest speed.Analysis of the trailing edge of the caudal finat the lowest speed shows that the dorsallobe leads the ventral lobe, while at the high-est speed both the dorsal and ventral lobesoscillate at the same rate.

20.2 LICKLITER, C.L.*, NISHIGUCHI,M.K., New Mexico State Univeristy. Phylo-genetic characterization of the genus Vibriobased on morphological and moleculardata.

Vibrio fischeri and Vibrio logei are twospecies of luminous bacteria (GAMMA-Proteobacteria) that reside as symbionts inthe light organs of a variety of sepiolidsquids (Cephalopoda: Family Sepiolidae).These squids include the genera Euprymnaand Sepiola, which are capable of exhibit-ing specificity towards their symbiotic asso-ciates. In order to better understand the evo-lutionary relationships between symbioticvibrios and other related species that arepathogenic or benign, we have examinedboth phenotypic and molecular data to de-termine the phylogenetic relationshipsamong particular Vibrio species. Phenotypicdata was obtained by analyzing several bio-chemical processes (based on enzymaticcapabilities), as well as measuring thegrowth rates of various bacterial strains inculture at two different temperatures (20ƒ or28ƒC). We also amplified and sequencedboth the 16S rDNA and glyceraldehyde phos-phate dehydrogenase (GapA) loci to obtainmolecular sequence data for each of theVibrio species used in the study. Combiningboth the morphological and molecular databetween the different Vibrio species has al-lowed us to determine which species aregenetically similar or distant, as well as helppredict the evolutionary radiation of the sym-biotic, pathogenic, and free-living speciesof the genus Vibrio.

P1.36LIGHT, D.B.*, DAHLSTROM, P.K.,Ripon College. Extracellular atp stimulatesvolume decrease in Necturus erythrocytesvia a p2x2 receptor. Receptor

Regulatory volume decrease (RVD) inmudpuppy (Necturus maculosus) erythro-cytes depends on a K+ conductance that isactivated during cell swelling. In addition,hypotonic swelling causes release of ATPinto the extracellular medium, which leadsto increased K+ efflux (Light et al. 1999. Amer.J. Physiol. 277: C480). This study was de-signed to determine the nature of the P2 re-ceptor involved in this process. Thehemolytic index (HI), a measure of osmotic

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fragility, was determined with a spectropho-tometer. This value decreased with extra-cellular ATP (50 ? MICROmolar), ATP-GAMMA-S (50 ? MICROmolar), and 2-MeS-ATP (50 ?MICROmolar). In contrast, adenos-ine (50? MICROmolar), UTP (50 ?MICROmolar) and ?,?-Me-ATP (50MICROmolar) had no effect on HI. Further-more, HI increased with the P2 antagonistsuramin (100 ? MICROmolar) and the P2Xinhibitor PPADS (10-100 MICROmolar), butnot with the P2Y antagonist RB2 (10MICROmolar). We also measured the per-cent volume recovery of cells following hy-potonic shock (0.5X Ringer) electronicallywith a Coulter counter. This value increasedwith extracellular ATP (50 ? MICROmolar),ATP?S (50 ? MICROmolar), and 2-MeS-ATP(50 ? MICROmolar). In contrast, suramin(100 ? MICROmolar) inhibited volume re-covery and this affect was reversed withgramicidin (5 MICROmolar). Adenosine (50MICROmolar), UTP (50 MICROmolar) and?,?-Me-ATP (50 MICROmolar) had no effecton RVD. Finally, we used the whole-cellpatch clamp technique to measure ion cur-rents directly. We found ATP (50MICROmolar) enhanced a K+-conductancethat was activated during cell swelling. Thiscurrent was inhibited by suramin (100 ?MICROmolar). Conclusion: our results aremost consistent with extracellular ATP acti-vation of a P2X2 receptor during cell swell-ing, which in turn leads to volume decreaseby enhancing K+ efflux. (Supported by NSFgrant MCB-9603568 and MCB-0076006.)

34.1 LIGHTON, J. R. B.*, TURNER, R. J.,University of Nevada at Las Vegas. Waterand carbon dioxide flux in the flutter phaseof the insect discontinuous gas exchangecycle (DGC).

The insect DGC is characterized by ex-treme variations in carbon dioxide releaseand oxygen uptake rates. During the flutteror F phase of the DGC, oxygen diffuses in-wards from a ca. 21 kPa external partial pres-sure to a ca. 4 kPa internal partial pressure.Is this process augmented by inward-di-rected bulk flow, caused by a negative trans-spiracular pressure gradient, as Kestler andothers surmise? JRBL and others have

shown that diffusive processes appear to besufficient to explain experimental observa-tions performed on F-phase carbon dioxiderelease. However, direct experimental evi-dence of F phase water vapor emission rateswith reference to carbon dioxide release rateshas been lacking because of the extremesensitivity of the required measurements.These experimental measurements are im-portant, because arguments for the evolu-tion of the insect DGC that are based onrestriction of respiratory water loss by theDGC, rather than the authors’ argument thatthe DGC is primarily an adaptation to gasexchange in hypoxic and hypercapnic con-ditions, depend vitally on the nature andbalance of the diffusive and convective pro-cesses taking place during the F phase. Inthis study we reveal the first experimentaldata on F-phase water vapor release anddiscuss the implications of our findings forthe diffusive model of the DGC’s F phase.NSF-BSR9306537, NSF-IBN9603873.

10.2 LIGON, D.B.*, PETERSON, C.C., Okla-homa State University. Physiological varia-tion in estivation among mud turtles(Kinosternon spp.).

Sonoran mud turtles (Kinosternonsonoriense) have long been believed to beobligately aquatic, yet recent evidence sug-gests that populations in the extreme east-ern portion of the species’ range thrive inhabitats that experience annual drying. Wecompared the physiological response to dryconditions of K. sonoriense from two popu-lations: one from Arizona, in which turtleshave been described as primarily aquatic,and one from New Mexico, in which exten-sive estivation has been documented. Forcomparative purposes, the responses ofgroups of K. flavescens (a well-documentedestivator) and K. hirtipes (a highly aquaticspecies) were also measured. All fourgroups were subjected to simulated dry-sea-son conditions in the laboratory. Restingmetabolic rates and rates of evaporativewater loss were measured prior to removalfrom water, after seven weeks of estivation,and following rehydration. Blood sampleswere drawn at the same intervals. Over thecourse of the study, Arizona K. sonoriense

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exhibited rates of mass loss similar to thoseof K. hirtipes, but that were higher than boththe New Mexico K. sonoriense and K.flavescens. Differences among groups wereevident in rates of evaporative water loss,resting metabolic rates, and several bloodchemistry variables, including Na+, K+, andBUN. The effects of behavior on physiologi-cal response to estivation were examined.

12.4 LIKNES, E.T.*, SWANSON, D.L., Uni-versity of South Dakota. Seasonal metabolicacclimatization in the American goldfinch re-visited: to what extent does summit metabo-lism vary seasonally?

Large seasonal changes in summit meta-bolic rate (Msum) have been considered onlya minor component of winter acclimatiza-tion in small birds. This conclusion is basedlargely on data from Cardueline finches, in-cluding American Goldfinches. Recent evi-dence from a wider diversity of species sug-gest that relatively large winter incrementsof Msum (25-50%) are common amongsmall passerines wintering in cold climatesand are associated with improved wintercold tolerance. In this study, we evaluateseasonal changes in cold tolerance, BMR,and Msum for American Goldfinches fromsoutheastern South Dakota. Goldfincheswere captured in winter (Jan-Feb), spring(April), and summer (Jun-Aug) and testedon the day of capture. Cold exposure testsinvolved subjecting individual birds to a de-creasing series of temperature in 79%He/21%O2 (helox) concurrent with open-circuitrespirometry. The helox temperature elicit-ing hypothermia was designated the coldlimit (Tcl). Winter goldfinches demonstratedsignificantly higher BMR (46%) and Msum(34%) and significantly lower Tcl (-9.5 vs.1.3†C) than their summer counterparts. Aprilgoldfinches also showed significantly higherMsum (24%) and significantly lower Tcl (-5.3†C) than summer birds. Winter birds hadhigher BMR (23%, P<0.05) and Msum (9%,P=0.066) than April birds. Winter birds alsohad significantly lower Tcl than April birds.These data indicate that prominent winterincreases in Msum are a component of win-ter acclimatization in goldfinches from SouthDakota. Furthermore, seasonal changes in

Msum accompany seasonal changes in coldtolerance, suggesting that Msum and coldtolerance are functionally linked.

33.4 LILLYWHITE, H.B., TU, M.C., Univer-sity of Florida, Gainesville. First ecdysis in-creases skin resistance to evaporative wa-ter loss in newborn snakes.

Aquatic-terrestrial transitions associatedwith nativity present numerous physiologi-cal challenges for terrestrial vertebrates, onebeing the requirement to limit excessivelosses of water due to evaporation. Epider-mal water barriers comprised of lipids pre-vent excessive water loss in the adults ofmost species, but little is known about de-velopmental mechanisms that establish orregulate these barriers. Newborn snakestypically shed their epidermis within a fewdays following birth, and behavioral changesare associated with this event. We employed20 newly hatched California king snakes(Lampropeltis getula) to test the hypothesisthat the first ecdysis is important for estab-lishing the epidermal barrier to cutaneouswater loss (CWL). We measured CWL withinthree days of hatching and again at threedays following the first ecdysis (9-14 dayspost hatching). Rates of CWL were quanti-fied using a RH/Dew Point meter to mea-sure water vapor density in partially satu-rated air flowing through an acrylic tube withand without a snake present. Each snakewas anesthetized to eliminate movementsand to minimize respiratory water loss.Boundary layer resistance was negligible inthe conditions of our experiments. We foundthat CWL was significantly lower (37.1 ± 1.2vs. 66.1 ± 4.3 mg/cm2- h), and skin resistancehigher (1118.2 ± 37.9 vs. 596.0 ± 31.6 s/cm),following the first ecdysis (P<0.0001). Suchchanges might explain the reclusive behav-iors of newborn snakes and might also ter-minate parental care of newborn pit vipersthat disperse away from parents followingthe first ecdysis. We are investigating thisphenomenon in pit vipers as well as the like-lihood that increases in cutaneous resis-tance are related to the deposition of lipidswithin the epidermis.

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70.3 LINDER, C.J., TSUKIMURA, B.*, Cali-fornia State University, Fresno. Inhibitory ef-fects of methyl farnesoate (MF) on the re-productive development of tadpole shrimp(TS), Triops longicaudatus.

To identify a reproductive regulator for theinvasive TS, T. longicaudatus, the hormoneMF was administered to growing juveniles.To administer MF, aquatic vectors (Artemianauplii) incubated in 0.05% albumin and 5mg/ml MF for 2 hours, were fed to TS dailyfrom hatching until 10 days of development.Oocyte development was observed by dis-section at days 5 and 10. Body cavity exami-nation of day 5 TS was a mean of 33.2 oo-cytes in the controls and 16.5 in the MFtreated (p<0.002, ANOVA). Day 10 ovarianweight was reduced from a mean of 1.1 mg(controls) to 0.6 mg (MF treated) (p<0.01,ANOVA). There were no somatic effects (bodyweights and lengths) between control andtreatment groups at day 5 or 10. To studyefficacy in rice fields, MF was added to shrimppellets with Tween-20 as a binding solutionat two treatment concentrations [low-0.0001% = 1 mg MF/kg pellets (MF1) andhigh-0.001% = 10 mg MF/kg pellets (MF2)].Initial lab tests of the pellets indicated thenumber of oocytes for MF1 treated TS at day5 were reduced from the controls (p<0.045,ANOVA). At day 10, ovary weight also de-creased (p<0.01, ANOVA), with no somaticdifferences. The MF2 treatment at days 5 and10 resulted in differences in body weight,body length, # of oocytes and ovarian weight,indicating a possible toxic effect. A randomblock design of 16 rings was set in a ricefield to study the MF1 and MF2 pellet treat-ments. At day 5, MF1 and MF2 treatmentsdecreased both ovary weight and GSI. Nosomatic effects were detected with MF1,however toxic effects were possible in MF2.At day 10, significant block effects obscuredany MF effects. MF appears to inhibit ova-rian development when administered to ju-veniles.

P1.84LOCKLAIR, M.R.*, GLAS, P.S., TheCitadel. Chitin type substances associatedwith the embryonic coat of the grass shrimp,Palaemonetes pugio.

The focus of this investigation is to deter-mine if embryonic coat proteins are com-

posed of chitin or chitin-type derivatives. Themorphological changes in the embryoniccoat were shown by Glas, et al., but the com-position of the embryonic coat has yet to bedetermined. Embryos were collected andtheir coats isolated during each stage of theirembryonic development. The isolates werethen electrophoresed on a gradient gel, fixedand stained for protein. Gels were alsostained for glycoproteins such as chitin. Also,some isolates were treated with chitinase,N-acetylglucosaminidase or both. The result-ing supernatants and pellets were run onPAGE. The results suggest the presence ofchitin or a chitin derivative in the embryonicenvelope. Determining coat compostitioncan be beneficial in a number of ways. Itcould be of assistance in the culture of re-lated species as food sources, environmen-tal monitoring, and in the biomedical field.More specifically the production of chitin orN-acetylglucosamine production by thegrass shrimpembryo might be of interest asa source of a flexible, resilient polymer forbiomedical groups, or as a source of the glu-cosamine gene. This study was supportedby The Citadel Developmental Foundation(PSG) and Charleston Scientific and Cul-tural Education Fund (MRL).

P3.18A LOEWEN, M. A., SAMPSON, S. D.;University of Utah, University of Utah.Hindlimb ontogeny in the Late Jurassictheropod dinosaur Allosaurus fragilis.

The Cleveland-Lloyd Dinosaur Quarry(CLDQ) of central Utah contains an exten-sive sample of Allosaurus fragilis, the larg-est known for any large theropod taxon. Thiscollection, along with isolated articulatedspecimens, forms the material basis of astudy of ontogenetic change in the hindlimbof this Late Jurassic theropod dinosaur. Pre-vious research assumed isometric growthin the hindlimb of Allosaurus. However, re-cent work has called this hypothesis intoquestion, suggesting instead that juvenilespossessed relatively longer hindlimbs thanadults. Hindlimb elements of Allosaurus havebeen subjected to gross morphological studyand analysis of cross-sectional geometry.The femur exhibits strong negative allom-etry in length as compared with ilium length.

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This indicates that juveniles had relativelylonger hindlimbs than adults. In contrast,ontogentic series of femoral cross-sectionsexhibit strong positive allometry in circum-ference, cortical bone thickness, and sec-ond moment of area. Moreover, femoralcross-sections exhibit a dramatic decreasein circularity. Specifically, greatest thicknessin adult femora occurs in the caudomedial-craniolateral plane, directly associated withinsertion of the major femoral retractor mus-culature (m. caudofemoralis). In total, thesefindings indicate substantial shifts in load-ing regimes during ontogeny. Ultimately,comparisons with extant taxa will be used toestimate changes in locomotor function.

16.1 LONDRAVILLE, R.L.*, DUVALL, C.S.,University of Akron. Fish respond to murineleptin injections by increasing intracellularfat metabolism.

Green sunfish (Lepomis cyanellus) wereinjected (i.p.) with murine leptin over thecourse of two weeks to test the hypothesisthat fish respond to leptin in a manner simi-lar to mammals. Leptin is a 16 kDa proteinhormone that controls metabolic rate andstorage of body fat in mammals; we recentlydemonstrated the presence of leptin infishes. If leptin signaling in fishes is similar tothat in mammals, then administering leptinshould lead to loss of body weight, decreaseof appetite, and increase in fatty acid me-tabolism. Fish were divided into three groupsof 10 each; the first group received 10 mgleptin per day for 9 days and 20 mg for 5days (IP injection); the second group receivedan equal volume of phosphate-buffered sa-line, and the third group was simply handled.All groups lost weight, but total weight, %dry weight, % body fat, cardiosomatic indexand hepatosomatic index were not differentamong groups. However, two indicators offatty acid metabolism approximately doubledin the leptin treated group: CPT inliver(carnitine palmitoyl transferase; 0.57 ±0.10; 0.28 ± 0.10; 0.25 ± 0.08 U/gm wetweight; LEPTIN, PBS, HANDLED, respec-tively; p<0.05) and FABP in heart (fatty acid-binding protein; 85.6 ± 6.1; 53.2 ± 10.1; 32.6± 4.1 % relative signal strength; LEPTIN,PBS, HANDLED, respectively; p<0.05).These data indicate that the leptin signaling

pathway is present in fish, and that it triggersan increase in fatty acid oxidation. Spon-sored by OhioSeaGrant #735489 and NIH#1R15DK5811301 grants to RLL.

P2.55 LONDRAVILLE, R.L.*, NIEWIAR-OWSKI, P.H., MCCONNELL, D.A.,ORCUTT, F.S., University of Akron. Coop-erative learning in large undergraduatescience classes.

Cooperative learning exercises were in-corporated into large (~100 student) sectionsof introductory undergraduate classes in Bi-ology and Geology. ‘Lecture’ was reducedby more than half, with most of the class dedi-cated to working in cooperative groups. Avariety of classroom assessment techniqueswere incorporated into the group exercisesto evaluate basic knowledge, critical think-ing, synthesis of information, and attitudesabout scientific issues. In-class group work,homework assignments, and pre-class read-ing quizzes accounted for up to 50% of avail-able points. Computer technology (multi-media, email and WWW) was strongly em-phasized. Comparing previous ‘lecture’ (L)sections to ‘cooperative’ (C) sections withininstructors, and comparing L vs. C sectionsbetween instructors assessed impact of thechange. Class attendance increased from~50% (L) to >90% (C). Performance on com-mon questions between L and C sectionswas not significantly different; however,within the C section, scores were significantlyhigher on questions based on the C exer-cises than questions taken from a test bank(Prob> F= .0018). Approximately 65% of stu-dents enrolled in the first semester of Biol-ogy (C) also enrolled in the second semes-ter, and 80% of that group enrolled in a sec-tion with the cooperative format vs. returningto the lecture format. These data, althoughpreliminary, suggest that the cooperativelearning format offers advantages over thelecture format. Anonymous surveys revealthat students overwhelmingly prefer C to L(88% vs. 12%) and approximately 75% ofrespondents believed that cooperative workhelped them learn course material. We arecontinuing our pedagogical revisions inother areas of the curriculum (non-majorsclasses, laboratories, and advanced/gradu-ate classes).

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P2.20LONG, K.L.*, MOORE, P.A., BowlingGreen State University. Attraction to mater-nal odor by juvenile crayfish, Orconectesrusticus.

Chemical odor cues have been found toplay an important role in the behavior andecology of several species of juvenile or-ganisms, including crayfish. In crayfish, can-nibalism occurs among juveniles of differ-ent broods, therefore chemical signals thatcan convey maternal status may be impor-tant for protection. The aim of this study is toidentify the role that maternal odor plays inthe life of the juvenile crayfish, Orconectesrusticus. Past research has shown that youngcrayfish are attracted to chemical odors pro-duced by any ovigerous female that is notnecessarily genetically related. Researchalso demonstrates that crayfish in the thirdstage of development, when recently sepa-rated from their mother, seek aid from her,acquiring protection when confronted by anunfamiliar chemical source. Our study testswhether juvenile crayfish are attracted tomaternal odors and whether non-maternalodors are aversive. The third stage juve-niles were isolated and tested in groups ofthree individuals selected from the samebrood in a Y-maze containing the pairedchemical cues of two adults or various con-trols. The variable measured was the timespent by each juvenile in both sides of a Y-maze. Our results suggest that an attractionto maternal odor exists for juvenile crayfish.These results indicate that juvenile crayfishmay have the ability to discriminate betweenmaternal and non-related female chemicalcues.

P2.62LOPEZ, Y., MOORE, A.M.F.,Universityof the Pacific. Assessing the weightthat black widow gumfoot lines can pick up.

Like other theridiid spiders, the blackwidow (Latrodectus hesperus) constructsgumfoot lines at the bottom of its cobweb.Gumfoot lines are vertical strands of silk thatare tautly attached to the surface and de-tach easily when an insect touches them.Sticky droplets on the gumfoot line pull theinsect into the air. Provided the insect is smallenough, gumfoot lines are effective traps. Inthis study, we determined how much weightcan be picked up by gumfoot lines. 27 black

widows were housed separately. They weregiven wooden frames to encourage con-struction of gumfoot lines of uniform 10 cmlength. We constructed 20 weights, rangingfrom 1-20 mg, out of insulated copper wire.We rolled each weight into 100 differentgumfoot lines. The gumfoot lines either (1)broke, without lifting the weight, (2) brokeand lifted the weight or, (3) attached to theweight but did not break. As the weight in-creased the percentage of threads that brokewithout lifting the weight increased, as didthe percentage of threads that attached tothe weight but did not break. As the weightincreased a smaller percentage of gumfootlines picked up the weight. The 1 mg weightwas picked up by 95% of the threads whilethe 20 mg weight was picked up by 3% ofthe threads. The percentage of threads thatpick up the weight appears to decrease loga-rithmically (R2 = 0.93) as the weight in-creases. Thus, gumfoot lines seem to be aneffective trap for insects of 10 mg and smaller.Tests of live insects are ongoing. (NSF DBI-9996072).

71.3 LOTT, D.B., ACKERMAN, R.A.*,Clarion University, Iowa State University. Ther-mal dose and embryonic sex determinationin Chelydra serpentina.

The thermal dose (degree hours) neces-sary to determine the sex of Chelydraserpentina embryos was assessed over twonesting seasons (1996,1997) using pro-grammable incubators. A total of 48 clutchesfrom Iowa, Illinois, Minnesota and Louisianawere divided among treatments and amongexperimental boxes within treatments wherethey were incubated fully buried in sand at -7 kPa. All treatment incubators were pro-grammed to produce an average tempera-ture of 25 C, which is close to the averagesummer soil temperature at nest depth inIowa. One incubator produced a constant25 C incubation treatment (control). The otherfour incubators were programmed to pro-duce quasi square wave thermal pulses inthe boxes (up 6 C and down 6 C for 1, 2, 4,and 6 hours in each daily cycle). The 6 Camplitude represented the average for Iowacalculated from an extensive data set of soiltemperatures at nest depth. Dose treatmentstrongly influenced hatchling sex with 0%

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females in the control, >90% females in the6 hr treatment and progressively more fe-males at each of the intermediate treatments(1,2,4 hrs). There appeared to be an influ-ence attributable to geographic origin. Doseresponse analysis indicates that about 160degree hours over the incubation period (I)were needed to produce 50% femalehatchlings. I was a positive function of in-creasing dose and was influenced by geo-graphic origin. Hatchling mass was not in-fluenced by treatment.

33.5 LOTZ, C.N., University of Wyoming.Effects of nectar concentration on water bal-ance, osmoregulation, and thermoregula-tion in a nectar-feeding sunbird.

The water balance of nectar-feeding ani-mals is inextricably linked to their energybalance. Because nectar secreted by bird-pollinated flowers can be dilute, birds canbe forced to consume high volumes of wa-ter to satisfy their energy demands. I exam-ined the consequences of feeding on dilutenectar for the African sunbird Nectariniachalybea (Nectariniidae). Sunbirds ingestedthe same amount of sugar over a wide rangeof sugar concentrations by modulating volu-metric intake. When feeding on 0.2 M su-crose, birds consumed four times their bodymass in water daily. Most of this water wasexcreted, with a remarkably small loss ofelectrolytes. Evaporative water loss wastwice as high in sunbirds fed 0.2 M sucrosethan in those fed 1.2 M sucrose. I estimatedthat birds used 10 % of their total daily en-ergy intake to warm 0.2 M sucrose from 20oC to body temperature, in contrast to thenegligible amount of energy used to warm1.2 M sucrose. To compensate for the in-creasing costs of evaporative heat loss andfood warming with decreasing food concen-tration, sunbirds maintained higher meta-bolic rates while feeding on lower nectar con-centrations. I hypothesize that the thermalinsulation of sunbirds feeding on dilute nec-tar is higher than that in birds feeding onmore concentrated nectar, because the in-crease in metabolic rate that I observed ac-counts only partially for the estimated costsof evaporative heat loss and food warming.

P3.19LOVEJOY, C.O.*, RENO, P.L.,MCCOLLUM, M.A., HAMRICK, M.W.,MEINDL, R.S., COHN, M.J., Kent State Uni-versity, OH, KSU, Case Western ReserveUniversity, Cleveland, KSU, KSU, Universityof Reading, UK. The evolution of primatehands: growth scaling registers with poste-rior HOXD expression.

The hands of great apes and humansare very similar morphologically but differsystematically in digital proportions. Thisimplies a modular basis of size. Since Ab-dominal-B-related Hox genes have beenshown to act as growth regulators in theautopod, we explored the size relationshipsamong elements which share their expres-sion. Our measurements, taken from a bal-anced sample composed of all 5 hominoidgenera (N=120), include the lengths of theproximal and distal radius (defined by thenutrient foramen), all 5 metacarpals, and theproximal 2 phalanges of each ray. Geomet-ric means of joint dimensions were used forsize adjustment. An ontogenetic series wasalso collected for Homo, Pan and Gorilla.We also monitored the expression of poste-rior HOXD genes in developing murineautopods using whole-mount in situ hybrid-ization of riboprobes. In situ hybridizationdemonstrates that the growth plates of thedistal radius and posterior 4 digits collocatewith Hoxd11 expression. ANCOVA shows astrong relationship between the posteriorrays and distal radial length, but none withits proximal segment. These data suggestthat hominoid digit and distal forearm pro-portions are modulated by responses ofgrowth promoting targets downstream ofposterior HOXD genes. Similar, relativelysimple, changes in gene expression canwholly explicate the probable pattern of evo-lution in the early hominid hand and fore-arm skeleton, including the emergence ofunusually short posterior digits and forearmsin the time period between Australopithecusgarhi and Homo habilis/erectus. Suchchanges are likely to be related to develop-ments in lithic technology and to be com-pletely unrelated to locomotion.

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15.2 LOVERN, M.B.*, MCNABB, F.M.A.,JENSSEN, T.A., Michigan State University,Virginia Tech, Virginia Tech. Developmentaleffects of testosterone on behavior in maleand female green anole lizards.

This study addressed the role of testoster-one (T) in the development of sexually di-morphic behavior in the green anole lizard,Anolis carolinensis. We described the de-velopmental pattern of endogenous T con-centrations, and determined the behavioraleffects of experimentally elevated T, in bothjuvenile males and females. T concentra-tions in the plasma of hatchlings from labo-ratory-incubated eggs and field-sampled ju-veniles of all sizes, as well as in the yolks offreshly laid eggs in the laboratory, were com-pared to plasma T concentrations in adultmales and females. There were no sex-spe-cific differences in plasma T in hatchlingsand small juveniles (< 26 mm snout-ventlength, SVL; < 14 d old). However, plasma Tsharply increased in juvenile males, but notfemales, after approximately 14 d post-hatch-ing, and it became significantly higher afterapproximately 38 d post-hatching (> 30 mmSVL). Plasma T for juvenile males was withinthe range detected in breeding adult fe-males, but it was 20- to 45-fold lower thanthat of adult males, breeding or post-breed-ing. Furthermore, eggs that gave rise tomales contained nearly twice as much yolkT on the day of oviposition as those that gaverise to females (0.9 vs. 0.5 pg/mg, respec-tively). Behavior trials revealed that, in com-parison to juveniles given empty implants,juvenile males and females given T-implantshad increased rates of nearly every behav-ior monitored, approaching those found inbreeding adult males. These results dem-onstrate that in spite of sex differences inendogenous T exposure during ontogeny,juveniles of both sexes exhibit an equiva-lent behavioral response to elevated T.

P3.46LUKER, L.A.*, HATLE, J.D., JULIANO,S.A., Illinois State University The effects ofphotoperiod on the length of the ovipositioncycle of the grasshopper, Romaleamicroptera.

The reproductive tactics of many insectsare affected by photoperiod because short-day photoperiods serve as a cue of the on-

set of winter. We tested several hypothesesregarding the effects of photoperiod on thelength of the ovipositioncycle of the Easternlubber grasshopper. We predicted that ovi-position would occur sooner in short-day(11.5L:12.5D) animals versus long-day(13.75L:10.25D) animals because the short-day animals would be in a photoperiod as-sociated with the Fall season. We also pre-dicted that costs associated with earlier ovi-position may be expressed as smaller sizeat the time of oviposition, fewer eggs, orsmaller eggs for females on the short-dayphotoperiod. Two different diets (low and highfood quantity) were tested at each photope-riod. The results indicate that the photope-riod did not have a significant effect on thetiming of oviposition within either diet treat-ment. Females in the two photoperiod groupsdid not differ significantly in size at the timeof oviposition in either diet treatment. In thehigh food treatment, there was no signifi-cant difference in the number of eggs be-tween the two photoperiods. However, inthe low food treatment, the short-day ani-mals produced significantly fewer eggs thandid the long-day animals. This suggests thatshorter photoperiod can alter reproductivetactics when food is limited.

S5.4 LUTZ, P.*, Prentice, H., Florida Atlan-tic University, Boca Raton. Sensing and re-sponding to hypoxia, molecular and physi-ological mechanisms.

In order to accommodate to low oxygenit is necessary first to be able to detect hy-poxia, then to initiate the appropriate mecha-nisms. There are two basic detectors: mo-lecular sensors that are directly linked togene regulation and metabolic indicatorsthat are triggered when the cell goes into astate of energy imbalance. The molecularresponses to oxygen deprivation in mam-mals are characterized in a variety of celltypes and include activation of oxygen sen-sors, signaling through specific promoter el-ements and subsequent downstream adap-tations. Many of the components are highlyconserved across species. A fall in ATP actsas a metabolic indicator of cellular energycrisis. In brain, in particular, there is a re-lease of adenosine which acts to reducemetabolic demand. We are investigating the

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extent to which altered molecular pathwaysof hypoxia sensing and adaptation may ac-count for the extraordinary ability of the turtlebrain to survive prolonged anoxia. Our ini-tial observations show differential expres-sion between normoxic and anoxic turtlebrains of transcripts encoding the immedi-ate early gene products c-fos and c-jun, theHSP-70 and the apoptosis regulators bcl-2and bax. Transcription factor binding assaysconfirm the presence of a hypoxia responseelement (HRE) binding activity in anoxicturtle brain and display anoxia regulatedbinding of the redox dependent factor NF-kappaB. In the anoxic turtle brain an earlyrelease of adenosine appears to mediatechannel arrest, reducing K+ efflux and Ca2+influx, and inhibit excitatory neurotransmit-ter release. The molecular characterisationof hypoxia sensing and adaptation in theturtle brain provides fundamental insightsinto cell signalling for neuroprotection andneuronal survival in the face of oxygen dep-rivation.

S10.17 LUTZONI, F.*, PAGEL, M., REEB,V., The Field Museum, Chicago, Universityof Reading, UK, The Field Museum, Chicago.Contribution of the lichen symbiosis to thediversification of fungi: a new approach todetermining confidence levels for ancestralcharacter states.

The acceptance by the mycological andlichenological communities, more than 12years ago, that basidiomycetes tightly asso-ciated with green algae or cyanobacteria arelichens, simultaneously established, for thefirst time, that lichens (including both asco-and basidiolichens) are derived from mul-tiple independent origins. Because approxi-mately one-fifth of all known fungi arelichenized and more than 98% of the diver-sity of lichens is within the ascomycetes, onecrucial question remains to be answered:How many independent origins of lichenstook place during the evolution of the asco-mycetes? To address this question we havesequenced a 1 kb and a 1.4 kb fragment atthe 5' end of the small and large subunits ofthe nuclear ribosomal DNA, respectively, for54 species representing 31 orders of asco-mycetes. The combined maximum parsi-mony analysis revealed two equally most

parsimonious trees. The ancestral charac-ter states (lichenized versus non-lichenized)were reconstructed for every node usingmaximum likelihood and by taking into con-sideration phylogenetic uncertainty. Theconfidence levels for each of the ancestralcharacter states were estimated by recon-structing the evolution of lichenization on alarge number of trees randomly sampledwithin the confidence envelope surround-ing the best trees.

36.2 LYNN, S.E.*, BENOWITZ-FREDERICKS, Z.M., HAYWARD, L.S.,WINGFIELD, J.C., University of Washing-ton, Seattle. Testosterone influences malebehavior during incubation but not duringthe parental phase in a temperate passe-rine.

Most monogamous male birds exhibita peak in plasma testosterone (T) in theearly spring coincident with territory es-tablishment and pair bonding. Once nestsare initiated, T declines precipitously andremains low as nestlings hatch and malesbecome parental. A growing body of evi-dence suggests there is a trade-off be-tween a maleís level of T and expressionof paternal care: high T is associated withreduced paternal care in favor of enhancedsexual behavior. Male chestnut-collaredlongspurs (Calcarius ornatus) show a highdegree of paternal care, including feed-ing and brooding young, acting as nestsentries, and aggressively defending thenest against predators. We experimen-tally altered the plasma level of T of maleC. ornatus such that the early spring T peakwas extended through the parental phase.T enhanced song behavior typical of thesexual phase and decreased nest sentrybehavior during incubation, but did notinterfere with brooding or feeding of nest-lings. Thus, males responded behaviorallyto T during incubation, but, unlike mostother monogamous birds studied, did notrespond to T during the parental phase.Through a series of male removal experi-ments, we determined that male chestnut-collared longspurs are critical for nestlingsurvival. Based on these data and similarresults in an Arctic passerine, we suggest

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that the pattern of malesí reduced respon-siveness to T during the nestling phasemay reflect the importance of male care innest success.

P2.8 MABEE, P.M., CROTWELL, P.L.*,BIRD, N.C., University of South Dakota, Ver-million. Models to explain directions of de-velopment and evolution of fin skeletons.

Data on development of radials and raysof median (dorsal, anal, caudal) and paired(pectoral, pelvic) fins were compared withina phylogenetic framework. We foundbroadly conserved phylogenetic patterns indirections of development within the differ-ent median and paired fins. Variability withinclosely related taxa (e.g. Percoidei) demon-strates the evolution of regional specializa-tion and new levels of independence withinformerly tightly integrated fin modules. Weconsider a module to be an element thatdevelops as an independent unit and un-dergoes coordinated changes in evolution.For example, the dorsal and anal fins de-velop in similar ways and undergo coordi-nated changes inevolution, thus may be clas-sified as a module. Previously unrecognizedpatterns in median fin development contrib-ute to our understanding of fin module de-velopment and evolution, and influence con-struction of genetic models to explain direc-tional phenomena. Based on constraints ob-served within these taxa, models consistentwith observed directional patterns were de-veloped. Hox gene activation or repressionmay account for location of median fins anddirection of radial formation within. Or, per-haps in analogy to butterfly wing eyespotdevelopment, specific genes are expressedin a pattern of symmetrical nesting, thus pat-terning fin location and development. Mod-ern genetic techniques will permit research-ers to test the models presented here, con-sequently significantly increasing our under-standing of the evolution and developmentof fin modules.

S10.6MACKIE, R.I., University of Illinois atUrbana-Champaign. Mutualistic fermentativedigestion in the gastrointestinaltract:diversity and evolution.

Animals of a wide range of orders orclasses have a portion of their digestive sys-

tem adapted to accommodate a fermenta-tion, which assists in digestion as well asproviding a varietyof other benefits. Becauseof the refractory nature of the plant cell walland the difficulty in digesting it, herbivoreshave anatomical and physiological adapta-tions of the digestive tract to allow assimila-tion of this material. Herbivorous reptiles,birds, and mammals usually have enlargedor elongated digestive tracts, often includ-ing fermentation chambers or sacs in theforegut and hindgut. Cecum-colon (hindgut)fermentors represent an older differentiationthan foregut fermentors which, in turn, areolder than ruminants. Advances in our un-derstanding of fermentative digestion havetended to obscure the vital role that the gas-trointestinal microbiota plays in the normalphysiological, immunological and protectivefunctions of the host animal. The associationof microbes with tissues of the gastrointesti-nal tract of animals during evolution has re-sulted in a balanced relationship betweenresident microbes and the host. In fact, allanimals including humans are adapted tolife in a microbial world. Numerous biochemi-cal, physiological and immunological fea-tures that are considered intrinsic charac-teristics of animal species are actually re-sponses by the animal to the physical pres-ence and metabolic activities of the normalindigenous microbiota. This microbial chal-lenge has modified the course of evolutionin animals resulting in the selection of ani-mal-microbe relationships which are com-plex and which vary tremendously rangingfrom competition to cooperation. Its highpopulation density, wide diversity and com-plexity of interactions characterize the gas-trointestinal microbial community.

8.3 MADERSON, P.F.A.*, ALIBARDI, L.,Brooklyn College of C.U.N.Y., University ofBologna. Origin and evolution of mamma-lian integument.

Maderson’s (1972) model proposed thathairs derived from mechanoreceptive epi-dermal appendages located betweentheropsid scales. It argued an initial role inthermo-regulatory behavior because such“protohairs” lacked insulatory properties (IP).Later quantitative changes in developmen-

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tal fields underlying their form and distribu-tion produced a “protopelage” whose IPwere the subject of later selection. The modeldid not consider the skin’s role as a barrierto cutaneous water loss (CWL) and couldnot readily explain the origin or initial selec-tive advantage of the postulated quantita-tive modifications of morphogenesis. Paleo-ecological analyses suggest that “true” ter-restrial ecosystems only appeared in theL.Trias, a time of major radiations of ad-vanced therapsids. Morphological diversityof CWL barriers in living amniotes suggestsindependent evolution in different clades.Residing in delicate epidermal tissues, suchbarriers must be protected from abrasive en-vironmental contact either by tough scales(extant reptiles), or by appendages (hairs orfeathers). The demonstration that a simplemolecular trigger causes hair follicle multi-plication suggests an explanation for pel-age origin and primary role. Unscaled, earlytherapsids living in “wet” habitats employedbehavioral thermo-regulation as do manyanuran amphibians. While some epidermaltoughening may have been achieved by in-corporation of histidine-rich proteins into AL-PHA-keratinizing cells, invasion of “dry,” po-tentially desiccating, abrasive environmentsnecessitated an appropriately protectedCWL barrier. A mutation causing multiplica-tion of protohairs would have provided suchprotection and would have spread rapidlypermitting speciation in the new “terrestrial”environment. The IP of this pilose skin formwere a protoadaptation (Gans, 1979) laterfavored as endothermy emerged.

P2.17MADIGAN, P.A., WATERS, K.A., HAR-RIS, L.G.*, University of New Hampshire. Ju-venile growth variation in the green sea ur-chin, Strongylocentrotus droe-bachiensis:possible roles for larval history, behavior andgenetics.

Growth of juvenile green sea urchins,Strongylocentrotus droebachiensis, hasbeen observed for three year classes, 1998,1999 and 2000. The urchins from 1998 and1999 were collected from juvenile settlementpanels set out from May to July at the Isles ofShoals off the New Hampshire coast. Theurchins used for the 2000 year class growth

studies were obtained from laboratory cul-tures originating from adults collected at theIsles of Shoals, so all individuals had a simi-lar larval history and settlement date.Throughout the study, urchins were main-tained under similar culture conditions andfed a combination of microalgal film andfleshy algae. Animals from 1998 and 1999were measured for test diameter on amonthly basis, while the animals from the2000 year class have been measured ev-ery two weeks. All three cohorts displayedconsiderable variation in growth rates un-der similar culture conditions. Larval historyand timing of settlement are two possibleexplanations for growth rate variation in thewild collected 1998 and 1999 year classes.Genetic variation between individuals is alsosuggested from the similar patterns of growthvariation shown by the laboratory reared2000 year class. Results also indicate thatbehavior may be important at high densi-ties, which has implications for aquacultureoperations.

44.2 MAGLIA, A.*, BUCHHOLZ, D.R., Uni-versity of Kansas, LME/NICHD/NIH. Hetero-chrony and patterns of osteogenesis inpelobatoid frogs.

Change in developmental timing is com-monly cited as the source of morphologicalevolution in anurans (and vertebrates ingeneral). Despite the warnings of Fink(1982), very few studies suggesting hetero-chrony as the cause of variation in anuranmorphology have tested their hypothesesin reference to a phylogeny. Primarily, this isbecause to do so, two things must be avail-able—a well-supported hypothesis of rela-tionships, and detailed developmental in-formation for the taxa in question. Herein,we examine ontogenetic series of four spe-cies of Pelobatoidea, a group for which thereare well-supported phylogenetic hypoth-eses. A total of 177 cleared-and-doublestained specimens representing postembry-onic ontogenetic series (Gosner Stages30‚46) of lab-reared Spea multiplicata,Scaphiopus couchii, Pelobates syriacus, andPelodytes ibericus, was examined for pat-terns of osteogenesis (including timing ofonset of ossification and degree of ossifica-

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tion at metamorphosis). Although S. couchiiand P. syriacus are similar in number of ossi-fied elements and amount of ossification atmetamorphosis, the time needed to ossify isremarkably different (P. syriacus = 23 days;S. couchii = 9 days). Moreover, S. multiplicataand P. ibericus both metamorphose 41 daysfrom hatching and resemble one another inpattern and degree of cranial ossification,but the time to onset of ossification of ele-ments is greater in P. ibericus (20 days) thanin S. multiplicata (11 days). These and otherheterochronic variations in osteogenesis ofthe four taxa will be discussed within theframework of a phylogenetic hypothesis. Is-sues regarding the examination of labora-tory-raised versus wild-caught specimensalso will be reviewed.

51.4 MAHON, A.R.*, AMSLER, C.D.,MCCLINTOCK, J.B., BAKER, B.J., Univer-sity of Alabama at Birmingham, University ofAlabama at Birmingham, University of Ala-bama at Birmingham, Florida Institute of Tech-nology. Chemo-tactile predator avoidanceresponses of the Antarctic limpet, Nacellaconcinna.

The antarctic limpet Nacella concinnahas the ability to escape potential predationby the highly mobile and predaceous seastar Neosmilaster georgianus. When the seastar comes into contact with the limpet, thelimpet undergoes characteristic avoidancebehaviors that include an extension of itspallial tenticles, a rasing of its shell in a mush-room-like fashion, a shell rotation, and flight.These behaviors were not induced by theomnivorous sea star, Odontaster validuswhich occupies the same habitats as N.georgainus. Crude hydrophilic extracts fromN. georgianus also induced the avoidanebehaviors, showing that this response ismediated by chemical as well as tactilestimuli. In the field, N. georgianus and O.validus were rarely seen feeding on N.concinna, and there was no difference inthe incidence of limpet predation betweenthe two sea stars. The escape behaviorsdisplayed by N. concinna appear to be aneffective behavior to deter predation by N.georgianus.

S13.2MAIENSCHEIN, J., Arizona State Uni-versity. Promoting interdisciplinary thinkingthrough biology and society programs.

We hear increasing calls for scientists tobecome involved in public arenas, yet weoffer too little training for such roles and wetypically offer it too late. By graduate school,students are already expected to concen-trate on their research. Faculty focus on pub-lishing and productivity. We argue that un-dergraduates are best prepared to benefitfrom multi-disciplinary education that in-cludes science policy, ethics, history, philoso-phy, and a range of other social issues. Anundergraduate major within the Biology De-partment at Arizona State University, an an-nual bioethics retreat for undergraduates,and student travel opportunities are the mainfeatures of our approach. Benefits then“trickle up” to the larger community.

P2.81MAIN, R. P.*, GRIFFIN, T. M., FARLEY,C.T., Harvard, University of California, Ber-keley University, University of Colorado,Boulder. Biomechanics of quadrupedal walk-ing: how do four-legged animals walk likeinverted pendulums?

Walking bipedal and quadrupedal ani-mals conserve mechanical energy by con-verting kinetic energy into gravitational po-tential energy and vice-versa. This invertedpendulum-like exchange is well understoodfor bipeds in which the center of mass (COM)vaults up and over the stiff support leg. How-ever, walking quadrupeds have 2, 3, and 4legs in contact with the ground at varioustimes during a stride, making it difficult tounderstand how the pendulum-like energyexchange occurs. In addition, the typical25% limb phase (percentage of stride timebetween successive limb contacts) of walk-ing mammals seems likely to cause the pec-toral and pelvic girdles to oscillate out ofphase, thus minimizing the vertical oscilla-tions of the COM. We sought to understandhow the limbs of quadrupeds function to al-low the COM to move like an inverted pen-dulum. We collected ground reaction forcesand video of 6 dogs walking at a range ofspeeds. We integrated the forces to deter-mine the velocity and vertical displacementof the COM, which were used to calculate

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the kinetic and potential energy fluctuations.Dogs saved up to 70% of the mechanicalwork required to lift and accelerate the COMvia the inverted pendulum mechanism. Twofactors were primarily responsible for this in-verted pendulum-like movement. First, theforelimbs supported the majority of bodyweight (63%). Consequently, the COM move-ments followed the forelimb movements,mimicking a walking biped. Second, dogswalked with a relatively short time betweentheir ipsilateral hindlimb and forelimb groundcontacts (limb phase = 15%), perhaps pre-venting the pectoral and pelvic girdles frommoving out of phase with each other. Sup-ported by UC Berkeley Gompertz Fellow-ship, NIH AR44688 and AR44008.

56.1 MALDONADO, T.M.*, JONES, R.E.,NORRIS, D.O., University of Colorado, Boul-der. Neurodegen-eration and amyloidosis inthe brain of kokanee salmon (Oncorhynchusnerka kennerlyi) during sexual maturationand senescence.

The brain of senescent kokaneesalmon exhibits neuropathology similar tothat of aging humans (Maldonado et al.,Brain Research. 858, 237-251, 2000).Beta-amyloid (ABETA) is distributed re-gionally in the salmon brain and its extra-cellular presence correlates with senes-cence. Brains of kokanee from one of fourreproductive stages (immature, maturing,mature and spawning) were stained withcresyl violet to visualize pyknotic neurons(neurodegeneration) in 24 specific regionsof the brain. Brains of immature and ma-turing fish exhibited only low levels ofneurodegen-eration compared to sexuallymature and spawning fish. Greatestneurodegeneration occurred in regionsimmunopositive for ABETA including thoseinvolved in gustation, olfaction, vision thestress response, reproductive behaviorand coordination as well as in thesuprachiasmatic nucleus and inferior lobeof the hypothalamus. Five regions showedneurodegeneration with no amyloidosis(ABETA deposition) whereas the nucleuslateralis tuberis and the Purkinje cells ofthe cerebellum showed neitherneurodegeneration nor amyloidosis. In

most regions, increased neuro-degenera-tion preceded ABETA deposition while insome regions it could not be determinedwhich appeared first.

14.2 MANZON, L.A.*, LAUDET, V.,YOUSON, J.H., University of Toronto atScarborough, Ecole Normale Superieure deLyon et CNRS, France, University of Torontoat Scarborough. Cloning and expression ofsea lamprey (Petromyzon marinus) thyroidhormone and retinoid X receptors.

Sea lampreys (Petromyzon marinus) areextant representatives of an ancient groupof vertebrates with a history that can betraced over 500 million years. A dramaticdecline in serum thyroid hormones (TH) oc-curs at the onset of lamprey metamorpho-sis, but the significance of this decline to theinitiation and progression of metamorpho-sis remains to be elucidated. Since, in mostother vertebrates, the effects of TH are gen-erally mediated by interactions with a thy-roid hormone receptor (TR) - retinoid X re-ceptor (RXR) heterodimer, we cloned thecDNAs for these receptors and examinedtheir expression over the lamprey life cycle.RT-PCR and 5' and 3' RACE yielded full-length cDNAs for two thyroid hormone re-ceptors (TR1 and TR2) and one retinoid Xreceptor (RXR). The deduced amino acid se-quences of these lamprey receptors wereapproximately 85-88% similar to those ofother vertebrates. Northern blotting usingRNA from several larval and adult tissuesindicated that the expression of TR1, but notTR2, is tissue- and stage-specific. SimilarTR expression patterns are also observedin other metamorphosing vertebrates. Ourlamprey RXR contains a deletion in the hingeand ligand-binding domains of the receptor,but its expression patterns have not yet beendetermined. The results of these cloning andexpression studies indicate that the se-quence, and perhaps the function, of thesereceptors has been conserved during ver-tebrate evolution. Furthermore, knowledgeof the expression of these receptors aids ourunderstanding of the role of TH in lampreymetamorphosis and provides insights intothe molecular mechanisms involved in thisdevelopmental event. Funded by NSERC.

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P3.63MANZON, R.G.*, YOUSON, J.H., Uni-versity of Toronto at Scarborough, Univer-sity of Toronto at Scarborough. In vitro inhibi-tion of thyroidal activity in the larval lampreyendostyle by potassium perchlorate.

The larval lamprey is unique among ver-tebrates because it lacks a follicular thyroidgland. In larval lampreys, thyroid hormonesare produced in the endostyle, asubpharyngeal gland. Moreover, contraryto the amphibian paradigm, lamprey meta-morphosis coincides with a decline in se-rum thyroid hormone (TH) titers and goitro-gens (anti-thyroid agents), which depressTH titers, can induce precocious metamor-phosis in lampreys. In this study, an in vitroexperimental system was devised to assessthe direct effects of the goitrogen potassiumperchlorate (KClO4) on radioiodide uptakeand organification by the larval lamprey en-dostyle. Organification refers to the incorpo-ration of iodide into lamprey thyroglobulin(Tg), an essential step in TH synthesis. Asingle iodoprotein, designated as lampreyTg, was identified in the endostylarhomogenates with polyacrylamide gel elec-trophoresis followed by autoradiographyand Western blotting. Lamprey Tg was im-munoreactive with a rabbit anti-human Tgantibody and had an electrophoretic mobil-ity similar to porcine Tg. When KClO4 wasadded to the incubation medium, both io-dide uptake and organification by the endo-style were inhibited, as determined bygamma counting and gel-autoradiography,respectively. Western blotting showed thatKClO4 lowered the total amount of lampreyTg in the endostyle. Based on the results ofthis in vitro investigation, we conclude thatKClO4 acts directly on the larval lamprey en-dostyle to inhibit thyroidal activity, thus sup-pressing the synthesis of thyroxine and tri-iodothyronine and resulting in a decreasein the serum levels of these two hormones.Funded by NSERC.

36.1 MAPLE, M.M., University of Kentucky.Direct and indirect effects of maternal rear-ing site choice on tadpole survival in thestrawberry arrow poison frog, Dendrobatespumilio.

Parental choice of early offspring envi-ronments can have important fitness conse-

quences for their young, especially in taxawith otherwise limited parental investment.The pathways by which site variables influ-ence fitness will determine the strength ofselection for site choice. In 1995 and 1996,I investigated the direct and indirect effectsof rearing site choice in Dendrobates pumilio,a frog with extended parental care. FemaleD. pumilio deposit their tadpoles inDieffenbachia and bromeliad axils that varyin age, water volume, pH, mean tempera-ture, and temperature variance. The resultsof this study indicate that female D. pumilioactively discriminate among abundantlyavailable rearing sites when depositing theirtadpoles and that these site choices mayhave both direct and indirect consequencesfor tadpole survival. Females consistentlychose younger rearing sites with greaterwater volumes in both years, and selectedon mean temperature in 1995. Although thefitness consequences of water volume andaxil age could not be assessed in this study,these axil characters are expected to havedirect effects on offspring survival. Variancein axil temperature had an indirect effect ontadpole fitness via its effect on tadpole growthin 1996; however, females showed no pref-erence for temperature variance when de-positing their tadpoles. These results areconsistent with the prediction that mothersshowing extended parental care will morelikely discriminate among sites (if they dis-criminate at all) based on characters havingdirect effects on offspring survival thanamong sites based on characters with onlyindirect effects.

S14.4MARSH-ARMSTRONG, N.*, BROWN,D.D., Carnegie Institution of Washington,Baltimore. Transgenic studies of metamor-phic changes in the nervous system of Xe-nopus laevis.

During Xenopus laevis metamorphosis,herbivorous filter feeding tadpoles that swimby flicking their tails are transformed into car-nivorous frogs that use their arms to shovelin food and their legs to swim. The nervoussystem changes during metamorphosis toaccommodate these new behaviors. Untilrecently, it has been difficult to dissociatenervous system changes from the otherchanges that occur during metamorphosis.

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However, the recent development oftransgenic technology in Xenopus laevisnow allows us to directly study the metamor-phosis of the nervous system. During meta-morphosis, the spinal cord develops the cir-cuitry to control arm and leg movement. Theinterference of thyroid hormone action in thespinal cord by means of nervous systemspecific transgenes leads to the develop-ment of limbs that look normal but that insevere cases lack any motion and in lesssevere cases have uncoordinated move-ment. Examination of these paralyzed limbsshow abnormal development of the neuro-muscular junction. Also during metamorpho-sis, the eyes shift their position and for thefirst time develop a region of visual overlap.Concurrent with these eye position changes,the retinas alter their proliferation pattern fromsymmetric to asymmetric and for the first timedevelop an axonal projection to the sameside of the brain. Transgenic interference ofthe action of the action of thyroid hormone inthe retina leads to inhibition of both thesechanges. Further, transgenic studies alsodemonstrate that the localized expressionof a thyroid hormone degrading enzyme inthe dorsal margin of the retina is sufficient toaccount for the asymmetry that develops inthe retina at metamorphosis.

P2.91MARSHALL, C.D.*, HERRING, S.W.,University of Washington. Motor control ofperioral muscles: somatotopic organizationin the pig facial nucleus.

The lips and cheeks of mammals form acomplex structure of constant volume thatappears to function as a muscular hydrostat.The muscles involved, primarily orbicularisoris and buccinator, are part of the facial mus-culature innervated by CN VII. Their finemotor control is likely accompanied by spe-cialized innervation. The degree of perioralmuscle elaboration is related to food acqui-sition and processing. For example, the lipsof herbivores (e.g., guinea pigs) are well de-veloped and complex compared to carni-vores (e.g., felids). The size and organiza-tion of the facial nucleus may reflect the be-havioral use of perioral muscles. The lipsand cheeks of pigs provide an intermediatemodel of a mammalian muscular hydrostatin which the innervation can be investigated.

We conducted a retrograde nerve tracingstudy of CN VII in pigs to determine (1) thelocation and morphology of the facial motornucleus, (2) the location of motor neuronpools that innervate perioral muscles, and(3) the organization of these motor pools.Lips and cheeks were injected with fluores-cent neurotracers. Subjects survived for 7days to allow retrograde transport of tracers.The pig facial nucleus is located in the ven-tral pontine tegmentum and is comprised of7 subnuclei. Perioral muscle motor neuronpools are found in 3 of the 7 subnuclei and,in general, are segregated from motor neu-rons innervating other facial muscles. Thesemotor pools are organized somatotopically;neurons within the lateral, ventral lateral, andventral intermediate subnuclei innervate thesuperior orbicularis oris, inferior orbicularisoris, and buccinator muscles respectively.The size and organization of the pig facialnucleus lie between those of guinea pigsand cats.

S12.3MARTIN, J.E., University of B.C.. Ad-vances through the insect hindgut.

How are insects able to maintain internalosmotic and ionic balance in the face of en-vironmental challenges? Since early stud-ies by Phillips which established desert lo-custs actively conserve water and producea hyperosmotic excreta, the question of howhomeostasis is achieved has been the cen-tral focus of his work. Utilizing isolated prepa-rations of hindgut segments, John˘s labo-ratory has developed a detailed model ofhindgut function and regulation. The ante-rior segment (ileum)reabsorbs the bulk ofentering fluid and delivers an isosmotic fluidto the rectum. Local osmosis and ion recy-cling allow the rectum to elaborate ahyposmotic absorbate and produce stronglyhyperosmotic excreta. 90% of water is re-cycled due in part to lateral membrane/mito-chondrial complexes present in the rectum.Metabolic support of transport is providedby luminal amino acids. Numerous solutetransporters have been characterized andlocalized in the hindgut and there is evidencethat many are hormonally regulated. Vari-ous tissue homogenates stimulate ion trans-port and are antidiuretic factors. One factor,ion transport peptide (ITP) has been puri-

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fied from locust corpora cardiaca and a par-tial amino acid sequence obtained. A par-tial cDNA corresponding to this sequencewas amplified and extended by polymerasechain reaction to give a complete cDNAwhich predicted a 72 amino acid peptidewith 3 disufide bridges and an amidated Cterminus. Synthesis of the predicted pep-tide resulted in a peptide whose biologicalactivity was identical to that of ITP purifiedfrom CC. Expression of ITP and mutant ITPpeptides in a Drosphila cell line indicateresidues important for binding and signaltransduction. There is now evidence for pep-tides structurally related to ITP in Coleoptera,Lepidoptera, and Diptera as well as Ortho-ptera and it will be very exciting to deter-mine their functions in whole animals.

35.5 MARTÌNEZ DEL RIO, C.*, SABAT, P.,SCHONDUBE, J. E., University of Wyoming,University de Chile, University of Arizona.Stable isotope composition as a covariatein comparative physiology.

When animals ingest different diets, theymust process contrasting arrays of nutrients,electrolytes, toxins and water. Hence, diet isa major determinant of an animal’s diges-tive and osmoregulatory traits and an im-portant independent variable in compara-tive studies. Characterizing diets, however,can be difficult. We propose the use of thestable isotopic composition of an animal’stissues as an indicator of its diet. We hypoth-esized that stable isotopic composition canbe used as a covariate in comparative stud-ies and used two systems to examine thisconjecture: phyllostomid bats and passerinebirds in the genus Cinclodes (Furnariidae).We used DELTA15N as a proxy variable forprotein ingestion in phyllostomid bats.Nectarivorous and frugivorous species werecharacterized by low values of DELTA15N,whereas insectivorous, sanguinivorous, andcarnivorous species were characterized byhigh values. The kidney’s concentrating ca-pacity increased with DELTA15N. In contrast,the capacity of the gut to process sugarsdecreased with DELTA15N. The genusCinclodes is unique among passerines inthat it includes species that live in hyperaridenvironments and feed on maritime envi-

ronments. It also includes species that liveand feed on terrestrial and fresh-water habi-tats. DELTA13C characterized the marineand terrestrial/fresh water diet of these birds,and hence the salt loads that they ingested.Kidney mass and relative medulary thick-ness, as well as the osmotic concentrationof urine and excreta, were positively corre-lated with DELTA13C within and among spe-cies. Our two examples highlight the poten-tial value of stable isotope composition datafor comparative analyses.

P1.44MARTINEZ, A.-S., TOULLEC, J.-Y.,SHILLITO, B., CHARMANTIER-DAURES,M.*, CHARMANTIER, G., University ofMontpellier, France, University of Paris,France, University of Paris, France, Univer-sity of Montpellier, France, University ofMontpellier, France. Osmotic and ionic regu-lation in the hydrothermal vent crabBythograea thermydron.

This study investigates the salinity tol-erance and the ability to osmoregulate andionoregulate of a brachyuran crab en-demic to the deep sea hydrothermal venthabitat, Bythograea thermydron. Crabswere collected during the HOPE 99 mis-sion from hydrothermal vents on the EastPacific Rise (EPR) on the 13ƒN and 9ƒNsites, at a depth of approximately 2500 m.Salinities of 32-34 ppt were measured inthe seawater surrounding the capturedspecimens. We found that this species is amarine stenohaline osmoconformer withtolerable salinities ranging between ap-proximately 31 and 41 ppt. The time of os-motic adaptation after a sudden decreasein external salinity was approximately 15-24h, which is particularly short for an adultbrachyuran crab. In the range of tolerablesalinities, it exhibited an iso-osmotic regu-lation, which was not affected by changesin hydrostatic pressure, and an iso-ionicregulation for Na and Cl. The hemolymphCa concentration was slightly hyper-regu-lated, K concentration was slightly hyper-hypo-regulated and Mg concentration wasstrongly hypo-regulated. These findingsprobably reflect a high permeability of theteguments of these crabs to water and ions.In addition, the presence of ionocytes was

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not detected through electron microscopy,and immunocytochemistry revealed theabsence of Na-K ATPase in all the struc-tures (gil ls, epipodites and branch-iostegites) of the branchial chambers. Nohistological difference was noted betweenanterior and posterior gills. These resultslead to the hypothesis that B. thermydron,as a stenohaline osmoconformer, lives ina habitat of stable seawater salinity.

64.6 MARTINEZ.G.M, University of NewHampshire. Muscle development in the long-finned squid using phalloidin staining meth-ods.

Whole mounts and serial sections ofembryonic and paralarval Loligo pealisquids were prepared and stained withphalloidinñrhodamine flourescent stainwhich binds to F-actin filaments. Stainingrevealed a network of actin filaments at dif-ferent densities at different stages. Musclesof the mantle, arms, tentacles and buccalmass were traced from Stage 17 to posthatching (staging according to Arnold, 1965).Particularly striking was the formation of thechromatophore musculature system, whichappears as a circular array around individualchromatophores. Extensive work on the func-tional morphology of cephalopod muscleshas been carried out by Kier et al., althoughthe actual ontogeny of major muscle sys-tems has not been followed. I here present anew method for investigating muscle devel-opment. This technique will also be usefulfor comparative studies, and in providingphylogenetically useful characters.

7.3 MASLAKOVA, S. A.*, MARTINDALE,M. Q., NORENBURG, J. L., George Wash-ington University, Kewalo Marine Lab, Uni-versity Hawaii, National Museum of NaturalHistory, Smithsonian In. Remains of thepilidium in direct developing nemerteans?

Nemertean worms display two basictypes of development: direct and indirect. Aspecialized planktonic larva, the pilidium,characterizes the order Heteronemertea. Thejuvenile worm develops via a unique form ofimaginal discs and sheds most of the larvalbody during radical metamorphosis. An en-capsulated larva, homologous to the pilidium,

is found in some heteronemertean species;in this case, metamorphosis takes placewithin the egg envelope. Species of two othermajor nemertean groups - the orders Palaeo- and Hoplonemertea have long been con-sidered to have direct development, al-though a few literature sources point to thepresence of larval epidermis, replaced bythe definitive epidermis during an encapsu-lated development in several species.Whether a direct or an indirect type of devel-opment is ancestral is a key question in stud-ies of evolution of the phylum. If this lost lar-val epidermis among palaeo- andhoplonemerteans can be shown to be ho-mologous to that of the pilidium larva, andtherefore plesiomorphic for the phylum, thiswould challenge the current, implicit viewthat direct development is primitive forNemertea. Here we present the first photo-graphs of the larval ectoderm of ahoplonemertean, as well as additional dataon the distribution of the larval ectodermamong hoplonemertean species. Our recentcell-lineage studies provide some evidencethat larval ectoderm of hoplonemerteansoriginates (at least in part) from the cells ofthe first quartet of micromeres. This supportsthe hypothesis that the larval ectoderm ofhoplonemerteans is homologous to the lar-val body of the heteronemerteans, as thefirst quartet of micromeres produces most ofthe pilidial body.

51.3 MATHEWS, L.M., University of Louisi-ana, Lafayette. Evolution of social mo-nogamy in snapping shrimp.

Social monogamy in the absence of bi-parental care is a topic of interest, as it ispredicted to be rare by parental investmenttheory, yet it occurs in a broad range of taxa.Most or all caridean shrimp of the genusAlpheus occur in heterosexual pairs, a so-cial organization that may have evolved asa form of extended mate guarding of femalesor territorial cooperation between partners.The mate-guarding hypothesis predicts thatmales should be able to detect female sexualreceptivity, and should prefer to associatewith females closer to receptivity. An experi-ment to test for distance communication ofgender and sexual status revealed that male

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A. angulatus are repelled by water contain-ing chemical cues from intermolt conspecif-ics (male or female) but are attracted to wa-ter containing chemical cues from premolt(pre-receptive) females. A mate-choice ex-periment showed that this is translated intoactive mate-choice decisions: males pairedwith premolt females significantly more thanwith intermolt females. The territorial coop-eration hypothesis predicts that individualsin pairs benefit through shared territorialdefense, by having a significantly lower riskof eviction from the burrow when faced withan intruder. Laboratory experiments showedthat females in pairs are less likely to beevicted than solitary females (p=0.034), butthere was no difference in the eviction ratesfor paired and solitary males. Furthermore,males were significantly more likely to aban-don the burrow if their mates were low-value(far from receptivity) than if their mates werehigh-value (p=0.004). These data togethersuggest that male and female A. angulatusare under different selective pressures lead-ing to social monogamy: males engage inextended mate-guarding, which is toleratedby females because of the advantages ofshared territorial defense.

16.3 MAURES, T.*, DUAN, C. University ofMichigan, Ann Arbor, University of Michigan,Ann Arbor. Expression of insulin-like growthfactor binding protein-1 in zebrafish.

Regulation of growth factor and hormoneaction by soluble hormone binding proteinshas emerged as a common theme for a va-riety of peptides including insulin-like growthfactors (IGFs). Among the best studied hor-mone binding proteins are members of theIGF binding protein (IGFBP) gene family. Sixdistinct high-affinity IGFBPs have been iden-tified and cloned. Each of these IGFBPs rep-resents an individual gene product, and isregulated differentially. The differential tissuedistribution and regulation patterns supportthe hypothesis that each IGFBP may have aunique function. The exact role of eachIGFBP in vivo, however, is poorly understood.This lack of knowledge is particularly evi-dent in the embryonic stage. Research inthis area has heavily relied on rodent mod-els, and attempts have been hampered by

the inaccessibility of the mammalian fetusenclosed in the uterus. Our laboratory hasbeen addressing this problem utilizing a te-leost model, the zebrafish. The free-living,transparent and fast-developing zebrafishembryos and the availability of numerousgenetic mutants make them a particularlysuitable model system. In this paper, we re-port the cloning and characterization of anIGFBP in zebrafish. Sequence comparisonand phylogenetic analysis results indicatedthat this protein is closely related to IGFBP-1. Its sequence identity to human IGFBP-1is 37%. RT-PCR analysis indicated thatIGFBP-1 mRNA is expressed in zebrafishembryos and adult tissues and its expres-sion is tissue-specific. Currently experimentsare undergoing to determine the spatial andtemporal expression of IGFBP-1 in all em-bryonic stages at single cell resolution. (Sup-ported by NSF Grant IBN-9728911).

13.4 MAYER, L.P*, DYER, C. A.,PROPPER, C. R., Northern Arizona Univer-sity. Sexual dimorphism in gonadal ste-roidogenic factor 1 (SF-1) expression dur-ing sexual differentiation and the effects ofoctylphenol on the differentiation processin the American bullfrog Rana catesbeiana.

Gonadal steroidogenesis during devel-opment is critical to differentiation of the adultsexually dimorphic phenotype and repro-ductive function. Environmental contami-nants may play a role in affecting the pro-cess of sexual differentiation through dis-ruption of steroidogenic action. Control ofthe steroidogenic pathway is regulated, inpart, by P450 cytochrome hydroxylases, andthe expression of many of these enzymes iscontrolled by the orphan nuclear receptor,steroidogenic factor-1 (SF-1). In mammals,SF-1 expression is critical for developmentof the reproductive axis and adult reproduc-tive function. In Rana catesbeiana duringsequential stages of development, we de-termined that SF-1 protein expression be-comes elevated in ovaries of sexually dif-ferentiating females, while expression in tes-tes decreases as differentiation occurs.Next, we exposed animals to the industrialpollutant, octylphenol (OP), for 24 hoursbefore and during the critical stages of sexual

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differentiation. We found that animals treatedwith OP prior to the normal time of differen-tiation underwent early gonadal differentia-tion and those that differentiated into femaleshad elevated SF-1 expression. This is thefirst study to investigate changes in SF-1during development at the protein level. Ourresults suggest that 1) SF-1 expression dif-fers between males and females duringsexual differentiation in a pattern similar tochickens and alligators, but different frommammals and turtles, and 2) OP affects thetiming of differentiation in bullfrogs demon-strating that OP has effects on developmen-tal processes.

P2.41MCALEER, M. W.*, GIRARD, I.,RHODES, J. S., GARLAND, JR., T., Univer-sity of Wisconsin-Madison. Motivation ofhouse mice artificially selected for highwheel running.

We have conducted an artificial selec-tion experiment in which 4 replicate lines ofhouse mice were bred for high wheel run-ning and 4 non-selected lines were main-tained as controls. At generation 24, micefrom selected lines were running approxi-mately 2.77-times as many revolutions perday as individuals from random-bred con-trol lines. As compared with the randombredcontrol lines, our selected lines of mice mayrun more on wheels because they have (1)higher motivation to run but similar physi-ological capacities for wheel running; (2)similar motivation but higher physiologicalcapacities; (3) both higher motivation andhigher physiological capacities. Researchto date has detected some differences inmorphological and physiological traits thatmay support wheel running, including re-duced body mass, more symmetricalhindlimb lengths, and enhanced capacity forinsulin-stimulated glucose uptake inhindlimb muscles. To measure motivation,we followed R. C. Bolles’ definition of moti-vation as a cognitive state for which multiplemeasures can be used to assess its level.The most appropriate measure may dependon the specific question, and it is likely thatno single measure can adequately capturedifferences in motivation. Hence, we usedseveral ways to increase the difficulty of

wheel running, and analyzed the propor-tional reduction in wheel running. Treatmentsincluded greater rotational resistance, 1 or2 hurdles placed in wheels, and insertion ofa tube between wheel and home cage. Dur-ing treatments with either 1 or 2 hurdles, theproportional decrease in total number ofwheel revolutions, the number of intervalsspent running, and the maximum number ofrevolutions during any 1-min interval wereall significantly less for selected-line animals.NSF IBN-9728434 and NIH P30 HD03352.

43.1 MCBRAYER, L.D.*, REILLY, S.M., OhioUniversity. The variation in feeding behaviorof scleroglossan and autarchoglossan liz-ards

One of the primary goals of functionalmorphology is the quantification of behav-ior in relation to morphological variation.The two major clades of l izards,scleroglossa and autarchoglossa, showsubstantial variation in cranial morphol-ogy, hyoid apparatus, tongue musculature,and the functional morphology of lizardfeeding. However, our understanding of thebehavioral variation present in lizard feed-ing is limited and no work to date has ad-equately described the range of behav-iors lizards use to ingest and process prey.The goal of this study is to describe andquantify the behavioral repertoire lizardsuse while feeding. Feeding bouts were vid-eotaped in a phylogenetically diversesample of lizard taxa and behavioral cat-egories were delineated. Five distinct typesof prey processing behavior were de-scribed (transport, inertial transport, side-to side movement, puncture crushing, and“palatal crushing”). All taxa engaged inprey transport behaviors. However, the fre-quencies of the five behaviors differedbetween scleroglossan and autarcho-glossan lizards. Per feeding bout,autarchoglossans consistently engaged inmore puncture crushing, transport, andtotal number of feeding behaviors. Also,autarchoglossans showed an increasedtendency to intersperse behaviors duringa feeding bout. Interestingly, all lizardsexhibited a previously undescribed behav-ior that we are calling “palatal crushing”.

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Here, the prey item was held and com-pressed between the dorsal surface of thetongue and the hard palate. Several hy-potheses will be put forth to explain thisbehavior as well as the behavioral varia-tion observed between scleroglossan andautarchoglossan lizards.

45.1 MCCAULEY, D.W.*, BRONNER-FRASER, M., California institute of Technol-ogy. Cranial neural crest cell migration in thelamprey Petromyzon marinus.

The neural crest is a vertebrate-specificpopulation of cells that gives rise to much ofthe peripheral nervous system, pigmentcells, and many craniofacial derivatives in-cluding facial bones, cartilage, teeth, andcranial ganglia. We have begun to investi-gate the origin of these cells in the lamprey,the most basal extant vertebrate. Here wedescribe the migration of cranial neural crestcells into the pharyngeal arches by using acell lineage tracer, DiI. Small regions of cellsalong the dorsal midline were labeled withDiI at the time of neural crest cell migration.Embryos were allowed to develop and werethen fixed at various intervals following mi-gration. We show that cranial neural crestmigratory pathways do not differ apprecia-bly from those previously demonstrated inmore derived vertebrates, such as the frog,even though the lamprey lacks such neuralcrest derivatives as jaws and true teeth. In-terestingly, although cells were labeled pos-terior to the hindbrain, no migratory crestcells were seen in this region. This observa-tion may relate to the lack of sympatheticchain ganglia, another neural crest deriva-tive not found in the lamprey. These studieswill be used to correlate the expression ofknown neural crest markers with migratorypathways to begin to understand the level ofconservation of neural crest developmentalmechanisms between basal and derivedvertebrates.

P2.76A MCCAY, M. G., University of Cali-fornia, Berkeley. The effects of aerodynamicstability on the dynamics of tree frog gliding.

Gliding has originated independently inat least two tree frog families, including thegenus Agalychnis (family Hylidae). Glidingtree frogs of both families possess features

such as enlarged, extensively webbedhands and feet and a unique gliding pos-ture. In a previous study, the aerodynamicstability of both derived gliding frogs andprimitive non-gliding frogs in the genusAgalychnis were very low overall and didnot correlate with any aspect of morphology.A possible explanation for the low stabilityfor all Agalychnis regardless of gliding abil-ity was that the low stability enhances thefrog’s maneuverability throughout theAgalychnis lineage. I investigated the ef-fects of aerodynamic stability on tree frogmaneuverability using a six-degree-of-free-dom computational model. This model ac-counted for the effects of the frog’s mass,morphology, and aerodynamic stability. Inaddition, the effects of wind gusts calculatedfrom wind gusts measured in the field werealso incorporated into the computationalmodel. The model demonstrates oscillationswhile gliding (Dutch roll) which have beenobserved in actual gliding tree frogs, andglide angles and glide speeds similar tothose observed from measurements of ac-tual gliding tree frogs. Higher body masstends to reduce maneuverability for a givenmorphology. I compared the maneuverabil-ity of a non-gliding tree frog and a glidingtree frog, and found that the reduced respon-siveness to maneuvering postures of thenon-gliding tree frog is ameliorated by itslower body mass compared to the moremassive gliding tree frog. Increasing (mak-ing more stable) or decreasing (making lessstable) the aerodynamic stability reduces theinitial response of a tree frog to a maneuver-ing posture, but does not change the overallmaximum turn rate.

P2.16MCCLARY, JR., M., Fairleigh DickinsonUniversity. Distribution of living barnacles inthe tidal Hackensack River.

The tidal Hackensack River of New Jer-sey contains sites where the barnacle,Balanus improvisus, lives, and sites wherethey once lived. To investigate the possibil-ity of increasing the distribution of living bar-nacles, five of ten rocks from the site wherethe barnacles live were transplanted to thesite where they once lived. The other fiverocks were not transplanted (controls). After

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nine days, the number of barnacles aliveand dead was counted. Although the de-crease in the percentage of living barnacleson control rocks (from 62% to 58%) was notsignificantly different, the decrease in the per-centage of living barnacles on transplantedrocks (from 70% to 14%) was significantlydifferent (X2

.05 (1) = 3.841, P < 0.001). Theresults suggest that the distribution of livingB. improvisus in the tidal Hackensack Rivercan not be increased by dispersal. Biologi-cal, physical, and chemical factors will betested in the future.

14.4 MCCLEARY, R.J.R.*, MCFAR-LAND,E.C., GRASMAN, K.A., MCNABB, F.M.A., Vir-ginia Tech, Blacksburg, Virginia Tech,Blacksburg, Wright State University, Dayton,OH, Virginia Tech, Blacksburg. Ontogeny ofUDP-GT activity in Japanese quail and ef-fects of PCB 126 on UDP-GT activity inchicken embryos.

U r i d i ned iphospha te -g lucu rono -syltransferases (UDP-GTs) are importantphase II liver biotransformation enzymes re-sponsible for conjugation of many endog-enous and exogenous substances in verte-brates. Induction of UDP-GTs has beenshown in birds exposed to pollutant chemi-cals such as PCBs and TCDD. BecauseUDP-GTs are responsible for the removal ofthyroxine from the circulation, their induc-tion can cause a concomitant decrease incirculating thyroid hormones (THs). To in-vestigate the development of UDP-GT activ-ity in precocial bird embryos, we examinedthe pattern of enzyme activity during differ-ent stages of embryonic (d12, 14, 16 and 17of incubation) and post-hatch (d<1, 1 and 7)development in Japanese quail. To eluci-date the effects of pollutant chemicals onUDP-GT induction in developing bird em-bryos, we dosed chicken eggs with the co-planar PCB 126 (0, .0512 to .80 ng/g egg)and sampled on d20 of the 21 day incuba-tion period. We validated a colorimetric as-say for UDP-GT activity in quail and chickenliver homogenate with Para-nitrophenol assubstrate. Plasma THs were determined byRIA. The development of quail UDP-GT ac-tivity shows low, stable activity pre-hatch, in-creasing activity during the peri-hatch pe-

riod and further increases in activity from d1to 7 post-hatch. In PCB-dosed chickens,there were no significant differences fromcontrols in UDP-GT activity, plasma thyrox-ine, thyroid gland weights or thyroid glandTHs. Thus, embryonic exposure to PCB 126did not cause thyroid disruption at sub-le-thal concentrations. However, additionalcongeners and PCB mixtures need to beevaluated for their effects on thyroid func-tion. Supported by EPA grant #827400-01-0 and a Sigma Xi Grant-in-Aid of Research.

47.1 MCCLINTOCK, J.M.*, JOZEFOWICZ,C., CARLSON, R., MANN, D.J., PRINCE,V.E., University of Chicago. Hox gene pat-terning and fish evolution.

We are using the zebrafish to investi-gate the evolution of Hox gene patterningfunctions. Whereas tetrapods possess 4clusters of Hox genes, zebrafish have 7distinct clusters. This condition is mostlikely due to a whole genome duplication,which occurred either early in or prior tothe radiation of teleost fish. Zebrafish haveat least 47 Hox genes, compared with 39in mouse and human. Why have these “ex-tra” Hox genes been maintained in thezebrafish? To address this question, wehave undertaken an analysis of thezebrafish homologues of DrosophilaLabial,the members of paralogue group 1(PG1). Zebrafish have four PG1 genes,whereas mouse and human have three.We find that two of the zebrafish PG1genes share an expression domain in theventral midbrain, well anterior to the re-gion that vertebrate Hox genes are thoughtto pattern based on both expression andfunctional data. Our data suggest that thispatterning role may be an ancestral fea-ture within the vertebrates which has beensecondarily lost in mammals. We haveused mis-expression to directly examinethe function of the four zebrafish PG1genes. We find that ectopic expression of3 of the 4 PG1 proteins leads to a homeotictransformation in the hindbrain such thatrhombomere 2 (r2) takes on characteris-tics of r4, as assayed by anatomical andmolecular markers. Thus, we find evidencefor evolution of PG1 genes at both cis-

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regulatory and protein-coding levels. Weare presently exploring the nature of thechanges in both regulation and proteinfunction.

P3.23MCEDWARD, L.R.*, MINER, B.G.,University of Florida, Gainesville. Diversityand evolution of larval patterns in ophiuroidechinoderms.

Ophiuroids have three larval types:ophiopluteus, vitellaria, and doliolaria, aswell as direct developing mesogens. Thereare four developmental patterns:planktotrophy, pelagic lecithotrophy, benthiclecithotrophy, and direct development.Lecithotrophic development is phylogeneti-cally widespread and occurs in more fami-lies (10 of 11) than does planktotrophy viaan ophiopluteus (5 of 10 families). In mostspecies with planktotrophic development,the pluteus is the final larval stage, but inone species, Ophiocoma pumila, theophiopluteus transforms into a pelagic,nonfeeding doliolaria at the onset of meta-morphosis. Pelagic lecithotrophic develop-ment occurs via a reduced pluteus or adoliolaria larva. Benthic development in-volves a reduced pluteus that metamorpho-ses before hatching, or a brooded vitellariaor mesogen. The ancestral ophiuroid lifecycle probably involved planktotrophic de-velopment via an ophiopluteus larva, fol-lowed by a pelagic, lecithotrophic doliolarialarva. Assuming that the loss of a feedinglarval stage is irreversible, then nonfeedinglarval development must have evolved atleast 10 times. Benthic development musthave evolved at least 9 times. Direct devel-opment has evolved at least twice in theclass. The doliolaria stage has been lost atleast 3 times, and the pluteus has been losta minimum of 9 times. There is a confusingarray of possible evolutionary transitions thatcould account for the diverse derived lifecycles and larval stages of ophiuroids. Sev-eral developmental patterns could haveevolved by alternative routes and if evolvedrepeatedly, by multiple routes. Unfortunately,the developmental diversity of the ophiuroidsis too poorly known to confirm or eliminatemost of these possibilities.

5.1 MCFADDEN, C.S.*, TULLIS, I.,HUTCHINSON, M.B., WINNER, K., HarveyMudd College, Claremont, CA. Rates of evo-lution of cnidarian mitochondrial genes.

Molecular phylogenetic and phylogeo-graphic studies of cnidarians have beenhampered by the apparently slow rate of mi-tochondrial gene evolution in this group.Genes such as COI, routinely used for popu-lation-level studies of other invertebrates,are often virtually invariant among conge-neric species of cnidarians. Nuclear rDNAsequences such as ITS, on the other hand,often evolve too rapidly to resolve the rela-tionships of congeners. We have developedPCR primers to amplify several regions ofthe soft coral mitochondrial genome (includ-ing ND2, ND6 and control regions) that mayprovide more phylogenetic resolutionamong species and genera than either ITSor COI. We have used these three mtDNAsequences to reconstruct the phylogeny ofseveral genera in the soft coral familyAlcyoniidae, and compare the rates of evo-lution and number of parsimony-informativecharacters in each region relative to COI andITS.

13.1 MCGINN, N.A.*, WALKER, C.W., Uni-versity of New Hampshire. Vitellogenesis inthe green sea urchin, Strongylocentrotusdroebachiensis: localization of vitellogeninprotein in gonadal tissue.

The green sea urchin, Strongyl-ocentrotus droebachiensis, is the focus of acommercial fishery and an aquaculture can-didate. It is therefore imperative that we un-derstand the general and reproductive biol-ogy of this species. In particular, vitellogen-esis is a process in sea urchins on whichlittle basic research has been done. Vitello-genesis is vital to successful reproductionand the vitellogenin protein may influencethe palatability of sea urchin roe. Sea ur-chins are unique in that males as well asfemales normally produce and usevitellogenin. This study explores some de-tails of vitellogenesis in the green sea ur-chin. Immunohistochemistry was performedon gonadal sections using a vitellogeninantibody prepared against a partial se-quence of a Strongylocentrotid vitellogenin

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protein. Immunohistochemical results pro-vide information on the localization of thevitellogenin protein in gonadal tissue. Novelobservations include the labeling of maturesperm and connective tissue cells associ-ated with the outer gonadal wall by avitellogenin antibody. This study and futurework on vitellogenesis in commercial seaurchin species will be important as naturalstocks continue to decline and interest inaquaculture increases.

7.2 MCGOVERN, TM, Florida St. Univer-sity Sex ratio bias in the clonal brittle starOphiactis savignyi.

Despite the prevalence of clonal organ-isms in many communities, few investiga-tors have explicitly related clonal and sexualmodes of reproduction. Clonal reproductionis likely to affect sexual reproduction in avariety of ways, including the alteration ofoperational sex ratios. Sex ratios in naturalpopulations of the clonal brittle star Ophiactissavignyi are consistently and significantlymale-biased. To explore the impact of clonalreproduction on sex ratios in this species, Iexamined patterns of clonal structure andconducted field experiments to determinegender-specific rates of clonal reproduction.Using RAPD patterns to demarcate clones,I have shown that male clones typically hadmore clonemates than female clones. Thegreater number of individuals in male clonescan explain the bias toward male individu-als in natural populations. In a field experi-ment in which I followed the fates of indi-viduals of known gender, I demonstrated thatmales are more likely to divide than females.This bias in division rates is likely respon-sible for the greater number of clonematesin male clones. Differences between thegenders in allocation to sexual reproduc-tion and the cost to sexual reproduction as-sociated with cloning may underlie the dif-ferences in rates of clonal division. Thesefindings demonstrate that differences be-tween the genders in rates of clonal divisionand the subsequent effects on clonal struc-ture have the potential to influence sexualreproduction on a population level by gen-erating a bias in the operational sex ratio.

41.5 MCGOWAN, C.P.*, O’REILLY, J.C.,NISHIKAWA, K.C., Northern Arizona Univer-sity, Flagstaff, AZ. Scaling of the feedingmechanism in the Colorado River toad.

There are several potential structural andfunctional consequences of an animalchanging size. As the whole animal grows,individual components that make up com-plex functional systems, such as the feedingmechanism, may grow at varying rates. Toexplore this issue, we examined the feedingsystem of the Colorado River Toad, Bufoalvarius, modeled as a simple mechanicallever system. We evaluated several aspectsof the feeding mechanism, including skullmeasurements, linear jaw measurements,mechanical advantage of jaw opening andclosing, jaw opening and closing muscula-ture and in vivo bite forces. Components ofthe feeding system were scaled againstbody length in order to test for isometry andestablish relative growth rates. The samplesize included 30 animals ranging from 15 to130 mm in body length as well as a sepa-rate group of 12 live toads in this size range,which were used to acquire bite forces. Theresults of the changing skull and jaw mor-phology were related to existing feeding ki-nematics for Bufo alvarius of a similar sizerange. Mechanical advantage remainedconstant for both jaw opening and closing,though the lever arms measured to deter-mine mechanical advantage were not iso-metric with respect to body size. The pre-dicted jaw Closing force was very similar tothat observed in vivo, but also did not scaleisometrically with size. The results of the pre-dicted jaw Opening forces however did notmatch that observed through kinematics,suggesting that some other component notexplored in this study is active in the ballistictongue protraction mechanism of this spe-cies. Supported by NSF 9809942 and aHooper Undergraduate Research Awardfrom Northern Arizona University.

1.2 MCHENRY, M.J., University of Califor-nia, Berkeley. Force generation by undula-tory swimming at intermediate Reynoldsnumbers in tunicate larvae (Botrylloides sp.).

Despite recent advances in computa-tional modeling and flow visualization, thehydrodynamics of swimming animals re-

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mains a subject of debate. This is certainlythe case for undulatory swimmers operat-ing at intermediate Reynolds numbers (Re),where both inertial and viscous forces areimportant. In the present study, propulsiveforces were measured in both tethered andfreely swimming ascidian ‘tadpole’ larvae(Botrylloides sp.), which swim at Re~100.These 2mm long larvae were tethered to mi-cro-capillary tubes with light suction. By mea-suring the stiffness of this tether, the total forcegenerated by the larval body was calculatedfrom tether deflection measurements. Forcesmeasured in tethered larvae were greatestin the lateral direction and were found tovary between 1 and 40 MU N among indi-viduals. These measurements were com-pared to theoretical predictions for lateralforces by applying blade element methodsto the axial kinematics of the tail. Predictedforces were also compared to the centrip-etal forces generated by freely swimminglarvae recorded in three dimensions withhigh-speed video. These measurements willprovide the basis for a more comprehen-sive treatment of the dynamics of helical swim-ming in larvae of ascidians and other ma-rine invertebrates.

P3.80MCINTYRE, J.C.*, MOORE, P.A.,Bowling Green State University. Boundary-layer effect on the chemical signal move-ment across the antennae of the maleantherea polyphemus.

Male A. polyphemus use pheromones inorder to locate females. The male detectsthe pheromones after it moves through theantennae. The antennae of the male arelarge and very plumose, and therefore havea significant boundary layer. The purpose ofthis study is to find out how the boundarylayer influences the movement of chemicalsignals to the receptors. The chemical sig-nal was measured using IVEC 10. In the firstpart of the study the angle at which the an-tennae faced into flow was manipulated, andin the second part we moved the electrodein a transverse fashion. Several parametersimportant for the detection of chemical sig-nals were analyzed, these included peaklength, peak rise time, maximum height, anddecay slope. The results show that the pres-ence of the antennae, the angle, and of the

position on the antennae impacts chemicalsignals parameters and t hus the informa-tion that male moths can extract from odorsignals.

14.5 McNABB, F.M.A.*, FOWLER, L.A.,PARSONS, C.M., GRASMAN, K.A., FOX,G.A., Virginia Tech, Blacksburg, Virginia Tech,Blacksburg, Virginia Tech, Blacksburg,Wright State University, Dayton, CanadianWildlife Service, Environment Canada, Hul.Thyroid function in herring gulls from PCB-contaminated Great Lakes sites.

We have investigated thyroid function inpipped embryos and prefledglings of her-ring gulls sampled in 1998 and 1999 at sev-eral Great Lakes sites with different amountsof PCB contamination and have comparedthem with gulls from the reference site, KentIsland in the Bay of Fundy. Previous studiesfound alterations in thyroid gland histologyand size in gulls from PCB-polluted GreatLakes sites, suggesting thyroid disruption inthese birds. Gulls collected in 1992 had de-creased organ masses (liver, kidney, spleen,adrenals) and thyroid gland hypertrophycorrelated with the sum of PCBs in pooledegg homogenates from different sites. In1998 and 1999, there was no consistentpattern of differences in plasma thyroid hor-mones (THs) or T4 to T3 conversion in brainof either embryos or prefledglings acrosssites. However, thyroid glands tended to belarger in embryos and were significantly hy-pertrophied in prefledglings from the highPCB sites compared to the reference site.Weight-specific thyroid gland TH contentwas significantly decreased in both embryosand prefledglings at high PCB sites in both1998 and 1999. Thus, despite thyroid glanddepletion of stored THs with high PCB expo-sure, developing herring gulls are able tomaintain their circulating THs at concentra-tions comparable to those in gulls from thereference site. Supported by EPA grant#827400-01-0.

53.2 MCWILLIAMS, S.*, W. KARASOV, J.LEAFLOOR, E. CAVIEDES-VIDAL, Univer-sity of Rhode Island, University of Wiscon-sin, University of Wisconsin, University

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Nacional de San Luis, Argentina. Digestiveadjustments in geese to reduced foragequality and its ecological implications.

When habitat quality on the breedinggrounds is poor, arctic-nesting geese musteat foods of lower quality than their preferredfoods. We tested the hypothesis that whengeese eat foods of lower quality (i.e., higherfiber), (a) they eat more, (b) their digesta re-tention time and digestive efficiency doesnot change, (c) their total capacity for break-down and absorption of nutrients increases,and (d) the mechanism responsible for theincrease in total capacity will be an increasein amount of intestine rather than an increasein intestinal tissue-specific enzyme activityor nutrient transporter activity. Contrary topredictions, Canada geese fed lower qual-ity food (50% fiber) had lower food intake,longer retention times, and larger foregutscompared to geese fed higher quality food(30% fiber). Digestive efficiency and tissue-specific enzyme and nutrient uptake activitydid not change with forage quality. Patternsof specific uptake rates and enzyme hydroly-sis rates suggest that geese feeding on rela-tively low quality diets maintain high rates ofileal uptake and thereby increase their inte-grated uptake capacity without the costs as-sociated with increasing hindgut mass. Inthe wild, geese compensate for the reduc-tion in food intake associated with reduceddiet quality by increasing feeding time; how-ever, there are limits to this strategy, espe-cially when risk of predation or disturbanceis high or when daylight is short. The in-crease in gut size associated with reduceddiet quality may represent the primary di-gestive constraint that determines the low-est quality of food eaten by geese that mustfly.

S6.9 MEAD, K. S., University of California,Berkeley. An interdisciplinary, multilevel ap-proach to olfaction in stomatopods.

Mantis shrimp rely on their sense of smellto find food, mates, and habitat. They sampletheir olfactory environment by flicking theirantennules with a rapid outstroke followedby a slow return stroke. Flicking facilitatesfluid and odorant access to the chemosen-sory sensillae (aesthetascs) on the anten-nule. I measured velocity gradients near dy-

namically scaled models of aesthetasc ar-rays from juvenile and adult stomatopodsusing particle image velocimetry. More fluidflows between the aesthetascs on the flickoutstroke than on the return stroke. Thisasymmetry ensures that new fluid is sampledduring each flick. The velocity data was in-corporated into an advection-diffusion modelof odorant molecule arrival at the aesthetascsurface. Odor molecules arrive at thesensillar surface more quickly during theoutstroke than during the return stroke of theflick, suggesting that the two strokes havedifferent functions. Odorant access is alsoaffected by the sensillar position on the an-tennule, and by the position along theaesthetasc. Reconstruction of serial trans-mission electron micrographs indicates thatthere are several features of both the inter-nal and external aesthetasc structure thatfacilitate efficient odor sampling. For in-stance, velocity gradients are steeper, per-mitting more rapid odorant access, along thedistal portion of the aesthetasc. This outerregion is where the aesthetasc cuticle is thethinnest, and where the outer dendritic seg-ments are the most highly branched, provid-ing maximum surface area for putative odorreceptors. Recent experiments, measuringodor concentration and velocity at the an-tennule as stomatopods track odor plumes,will help us discover how stomatopods useodor arrival information to navigate to theplume source.

P2.61MEAD, K. S., University of California,Berkeley. The mechanisms of turbulent ac-tion: how does hydrodynamic shear stressaffect fertilization and development in seaurchins?

Marine invertebrates that reproduce byexternal fertilization release their eggs andsperm into the water column. For animalsliving in the surf zone, this means that theirgametes are exposed to high energy dissi-pation rates (up to 3000 W/m3) associatedwith breaking waves. To test the effects ofsurf zone turbulence, fertilization experi-ments were carried out in a Couette cell, adevice that creates reproducible energy dis-sipation rates. Gametes from seven speciesof sea urchins were exposed to energy dis-sipation rates typical of wave-exposed surf

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zones. Exposure to high energy dissipationrates during fertilization decreased fertiliza-tion and developmental success in severalspecies. The energy dissipation rate createdin the Couette cell is affected by both thevelocity gradients in the fluid, and the vis-cosity of the fluid. Some potential mecha-nisms of turbulent action vary with viscosity,and others are affected by the velocity gra-dient. To assess which mechanisms of tur-bulent action might be operating viscosityand velocity gradient were varied separatelyin a series of Couette cell experiments. Apotential mechanism of turbulent action thatemerged from this analysis was that surf zoneturbulence might affect fertilization successis to interfere with gamete binding. This hy-pothesis was tested by counting the num-ber of sperm bound to eggs after exposureto energy dissipation rates during fertiliza-tion. In addition, the importance of egg size(relative to turbulent eddy size) is discussedfor fertilization and development.

12.5 MEAGHER, E.*, PABST, D.A.,MCLELLAN, W., WESTGATE, A., WELLS, R.,University of North Carolina, Wilmington,Duke University Marine Lab, Chicago Zoo-logical Society. Heart rate, respiration andheat flux across the dorsal fin in wild bottle-nose dolphins, Tursiops truncatus.

The dolphin dorsal fin is a thermal win-dow, invested with blood vessels that func-tion to conserve or dissipate body heat de-pending on thermoregulatory demands.Heat flux, measured at a single position onthe dorsal fin of bottlenose dolphins, de-creases during dives, relative to values mea-sured at the surface (Williams et al., 1999).This decrease has been attributed to dimin-ished peripheral blood flow as a result ofbradycardia during a dive. Dolphins, how-ever, are arrhythmic breathers, experienc-ing cycles of bradycardia, followed by anassociated tachycardia during respiration,even while resting at the surface. Thus, wehypothesized that heat flux across the dor-sal fin would decrease during apneustic pe-riods at the surface. We took simultaneousand continuous recordings of heart rate, res-piration and heat flux at three positions onthe dorsal fin (in air and with fin submerged)

of 19 wild bottlenose dolphins. Tachycardiawas associated with each respiratory eventand heart rate, although variable, decreasedduring intervening breathholds. Heat flowacross the dorsal fin in air ranged from -60W/m2 (gaining heat) to 150 W/m2, while heatflow during submergence ranged from 25W/m2 to 225 W/m2. Although no consistentpattern between heart rate and heat flux wasevident, heat flow values depended stronglyupon fin position. Heat flow measured at twosites on the center of the fin- one directlyover a superficial vein and the other pur-posely avoiding a vein- could differ by asmuch as 125 W/m2. These results suggestheat flux across the dorsal fin is strongly in-fluenced by underlying patterns of vascula-ture. Funded by NMFS.

P2.89MEDINA, C.L., KOESTER, D.M.*,LUER, C., University New England,Biddeford, ME, University New England,Biddeford, ME, Mote Marine Laboratory,Sarasota, FL. Development of the electricorgan of the skate, Raja eglanteria.

The electric organ of Raja eglanteria con-sists of paired, longitudinal columns ofelectrocytes within the lateral musculatureof the tail. Although it is known thatelectrocytes develop from embryonic hy-paxial muscle fibers within the tail, little in-formation exists on the stages of this differ-entiation process. Examination of H&Estained paraffin sections through the tail ofskate embryos sampled at weekly intervals(hatching occurs around week 12) and at 3months post-hatching, reveals that eachelectrocyte develops from a single skeletalmuscle fiber. Prior to the 4th week of devel-opment the tail consists exclusively of skel-etal muscle fibers oriented in a rostrocaudaldirection. During the 4th week some of theskeletal muscle fibers begin to differentiateinto electroblasts. Electroblasts are distin-guished from adjacent skeletal muscle fibersby an increase in number of nuclei and ashortening of fiber length. As developmentproceeds (weeks 6-8), electroblasts con-tinue to shorten as the rostral end expandsto form a club-shaped cell. In addition, nervefibers appear at the rostral end of eachelectroblast indicating formation of the mo-

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tor end plate. Further expansion of the ros-tral end and regression and thinning of thecaudal end result in the formation of a thick,transversely oriented disc-like cell by the10th week. The 3 layers of a typical disc-shaped electrocyte, which include the elec-tric plate, striated, and alveolar layers, areeasily identified at this time. Further devel-opment of the electrocytes up to and afterhatching involves an expansion and thin-ning of the disc in the transverse plane.Electrocytes of Raja eglanteria are fully dif-ferentiated by 3 months of age.

P1.95A MEDLER, S., Colorado StateUniversity. Comparative trends in maxi-mum shortening velocity and tetanic ten-sion: influence on skeletal muscle diver-sity.

Maximum shortening velocity (Vmax) andmaximum tetanic tension (P0) are two de-terminants of a muscle’s contractile proper-ties. Muscle power output, contractile effi-ciency, and ultimately the energetics of lo-comotion are all linked to Vmax. P0 defines amuscle’s force production and is generallyconsidered to be constant, although signifi-cant differences have been found amongsome fiber types. In this study, publishedvalues of Vmax and P0 for more than 90muscles representing three phyla and about50 animal species were analyzed. P0 wasfound to be constant at about 150 kN/m2,being unrelated to body mass, phylogenicgroup, or shortening velocity. As such, P0

may represent a design constraint in theevolution of skeletal muscle diversity. In con-trast, a significant inverse correlation (p <0.0001) was found between body mass andVmax in locomotory muscles, consistent withHill’s observation that smaller animals pos-sess faster muscles. Body mass alone ac-counts for almost 50% (r2 = 0.48) of the vari-ability among the different shortening veloci-ties, independent of either phylogenic groupor mode of locomotion. Neither the ultimatecause nor the molecular mechanisms re-sponsible for this scaling effect is fully un-derstood. The mass exponent of –0.19 isabout the same as described for quadrupe-dal mammals, but is derived from a muchmore diverse group of animals than previ-

ously studied. At a molecular level, differ-ences in Vmax are generally associated withdifferent myosin isoforms and this is prob-ably the case here. How animals experi-encing indeterminate growth sense masschanges and then appropriately switch theirmuscles’ contractile properties is unknown,but provides an interesting model of muscu-lar plasticity.

27.1 MEIJER, K*, LIBBY, T.M., FULL, R.J.,University of California, Berkeley. Passivestability provided by the musculo-skeletalproperties of an insect leg.

Cockroaches have an amazing ability torun over rough terrain. It has been hypoth-esized that their ability to perform stable lo-comotion in unstructured environments is fa-cilitated by the mechanical properties of theirmuscles and exoskeleton. To investigate thepassive stabilizing properties of individuallegs, we measured the mechanical imped-ance of the metathoracic limb of tetheredcockroaches (Blaberus discoidalis). The hindlimb of the cockroach was attached to amuscle lever system with a stainless steelrod. Sinusoidal length oscillations (2-25 Hz,1-5 mm) were imposed on the hind limb inthe plane of leg movement when muscleswere relaxed. The resulting angular changesof the coxa-femur and femur-tibia jointsamounted to 10-40 % of their natural rangeof motion. We found that the peak leg forcesin response to the length oscillations rangedfrom 2.8 - 8 mN, which is within the rangereported for single leg forces of freely run-ning cockroaches (Full et al., 1991). Analy-sis of the displacement- force data indicatedthat the leg behaves as a spring-damper sys-tem. The magnitude of impedance (Dforce/Dlength) ranged from 5-15 mN/mm andshowed no effect of oscillation frequency.These values are substantially lower thanthose found for out of plane oscillations. Itsuggests that in a relaxed animal the re-sponse is slower for planar vs. non-planarperturbations. The tangent of the phaseangle increased with frequency from 0.2 -0.9, indicating that a significant part of theenergy introduced by perturbations is dissi-pated in the leg. Our next step is to use amodel of the cockroach leg to determine the

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muscle and exoskeleton contributions to themeasured leg impedance. Supported byONR N00014-98-1-0669.

P3.95MENDONCA, M.T., TRUCKS, K.T.,Auburn University, Auburn. Comparison ofaromatase activity in female yellow-blotchedmap turtles from contaminant impacted vs.reference sites.

Yellow-blotched map turtles, Graptemysflavimaculata, from a portion of thePascagoula River drainage system in Mis-sissippi, USA, impacted by paper mill efflent,exhibit low reproductive rates. Significantlyfewer females from a historically contami-nated site develop second clutches whencompared to females from a reference site(e.g. 17% vs 50%). However, there were nosignificant differences found in the monthlymean plasma 17BETA-estrodiol (E) levelsof females from the two sites. Female fishfrom sites contaminated by bleached kraftmill effluent exhibit lowered E as well as low-ered ovarian aromatase activity. We com-pared aromatase activity in ovarian and he-patic tissue of females collected from an im-pacted and reference site in June-July, 1999.Female map turtles from the contaminatedsite exhibited significantly lower mean ova-rian aromatase activity levels than those fromthe reference site. Hepatic aromatase activ-ity did not differ between sites. In June-July2000, we collected additional females fromthe two sites, and biopsied several ovarianfollicles from them. The difference inaromatase activity between sites using thebiopsied follicles did not differ from the pat-tern found when entire ovaries were used in1999 when corrected for protein content.Additionally, we examined the levels ofaromatase mRNA of embryos from impactedand reference sites and these results will bediscussed. This research funded by Missis-sippi-Alabama Sea Grant R/ER-43PD.

15.6 MENDONÇA, M.T., Auburn University.Effects of temperature, testosterone, andflutamide on mating in male big brown bats.

Male big brown bats exhibit a dissoci-ated pattern of reproduction. They mate inthe late fall and throughout the winter uponperiodic arousal from hibernation when tes-tosterone (T) is basal and gonads are re-

gressed. In previous experiments, malesmated even when gonadectomized (GX)several months before the beginning of themating season, if they are exposed to aninitial period of 5 C for 7 d and then allowedto return to 22 C. However, GX males givenflutamide (F) did not mate until the very endof the test period (Mar, 1999). In Jan-March2000, we continued to examine the interac-tions of temperature and T on male matingbehavior. Males were divided into 5 groups:INTACT, SHAM, GX, GX+T, and GX+F. Malesfrom each group were divided into 3 tem-perature regimens: constant 22 C (CON-STANT), repeated exposures of 5 C for 7 d(LONG), and repeated exposures to 5 C for1 d (PULSE) with returns to 22 C for 4 d.Based on previous data, we predicted malesnot exposed to low temperature (CON-STANT) would not exhibit mating behavior.Contrary to prediction, males of all treatmentgroups (including GX+F) exhibited matingbehavior when exposed to CONSTANT.However, INTACT males exposed to LONGexhibited significantly higher levels of mat-ing behavior than INTACTs exposed toPULSE or CONSTANT conditions. Addition-ally, when, after 2 months, the CONSTANTgroup was given LONG exposure, malesfrom all treatment groups exhibited signifi-cantly higher levels of mating. This result ar-gues that exposure to low temperatures fora period of time does potentiate mating be-havior in males of this species. Especiallyintriguing was the behavior of the GX+Fgroups. The CONSTANT GX+F males ex-hibited significantly much higher matingscores than those in the PULSE and LONGcondition. Thus, it appears flutamide is inef-fective at blocking mating behavior at highertemperatures but seems effective when ani-mals are exposed to either short or long pe-riods of low temperature with subsequentwarming.

S14.5MENON J.*, FRESSE, D., WilliamPaterson University of New Jersey, Wayne.Effects of hormones/morphogens in anuranmetamorphosis.

Retinoids, a large family of natural andsynthetic compounds related to vitamin A,have pleiotropic effects on embryonic de-velopment. The role of retinoids in pro-

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cesses such as cell proliferation, differen-tiation and apoptosis is well documented.Heterodimerization of retinoid X receptors(RXRs) with receptors of thyroid hormone(TRs) is crucial for action of the latter, re-sponsible for tissue remodeling duringmetamorphosis. Presently we found thatretinol palmitate (10-6 M) treatment duringprometamorphic stage (stage 55/56Nieuwkoop and Faber, 1967) acceleratesmetamorphic events in tadpoles of Xeno-pus laevis as confirmed by morphologi-cal, histological and ultrastructural obser-vations in various organs. A further accel-eration was seen when treated with ret-inol (10-6 M) plus thyroxine (10-6 M) indi-cating their synergistic mode of action. Incontrast, no such positive effects wereseen in Rana catesbeiana tadpoles whentreated during mid prometamorphic stage.However, retinol treatment duringpremetamorphic stage, inhibited metamor-phosis in both the species of tadpoles. Weused high performance liquid chromatog-raphy (HPLC) to identify, and quantify con-centrations of retinoid metabolites presentin tissues such as tail, body skin, liver andlimbs of both the species under differentexperimental conditions. Our results indi-cate significant differences in retinol me-tabolism between the two species, whichare correlated with the species differencesin response to retinol treatment.

P3.62MENON, J., ROBERTS, R.*, DAVILA,I., William Paterson University of New Jer-sey. Influence of peroxisome proliferator ac-tivated receptor (PPAR) and retinoid recep-tor agonists on tail epidermis and limb budsof Xenopus laevis in vitro.

Members of the superfamily of nuclearhormone receptors, which are obligateheterodimeric partners of the retinoid X re-ceptors, may be important in amphibian post-embryonic development. Here, we exam-ined the effects of retinol palmitate, and ofclofibrate (agonist of peroxisome proliferatoractivated receptors ñ PPARs) on two organs- tail epidermis and limb bud of the tadpolesof Xenopus laevis in vitro . Amputated tailsand limb buds during (stage 54/55,Nieuwkoop and Faber, 1967) were main-

tained in vitro with two retinol concentrations(10-6 M,10-5 M) and clofibrate (10-3 M). Tailsand limbs were maintained in culture me-dium for 72 h and 96 h respectively and tis-sues were processed for electron micros-copy. In Xenopus laevis, tail epidermis is bi-layered with underlying collagen layers.While there were no observable changes intail epidermis retinol concentration of 10-6

M, higher retinol concentration (10-5 M) in-duced large-scale apoptosis and sloughingof the epidermis. Limb buds, when treatedwith retinol showed differentiation of the dig-its. Clofibrate treatment induced significantepidermal lipid deposits and loss of struc-tural integrity of tail epidermis. No change incartilage differentiation was observed in thelimb buds following clofibrate treatment. Wehypothesize that at developmental stage 54/55, PPAR agonists may not have a signifi-cant role to play in limb morphogensis incontrast to ligands of retinoid receptors andthe effects of PPAR agonist in tail tissue maybe related to a different developmental fate(regression) of this organ.

P1.1 MEYER, H.A., McNeese State Univer-sity. Tardigrada of Arkansas and Louisiana.

Outside of the states of Texas and Ala-bama, the distribution of limnoterrestrial tar-digrades in the American Deep South ispoorly known. There are no publishedrecords from the states of Louisiana andMississippi, while in Arkansas only one spe-cies has been reported. As part of a long-term study of tardigrade distribution and ecol-ogy in the region, I began sampling for Loui-siana and Arkansas tardigrades in the springof 2000. In Louisiana, I sampled mosses andlichens from two sites in Calcasieu Parishand one in Natchitoches Parish. No tardi-grades were found in ground mosses (Sph-agnum sp.). From mosses and lichens ontrees I identified seven species of tardigrade,belonging to four genera. No sample con-tained more than two species of tardigrade.Mosses and lichens obtained from trees androcks in the Ouachita and Ozark Mountainregions of western Arkansas contained fif-teen species of tardigrade. The number ofspecies per sample ranged from one to six.

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43.2 MEYERS, J.J.*, HERREL, A.,NISHIKAWA, K.C., Northern Arizona Univer-sity, University of Antwerp, Northern ArizonaUniversity. Morphological specializations ofthe feeding system in horned lizards(Phrynosoma).

Lizards of the genus Phrynosoma havelong been noted as dietary specialists, feed-ing predominately on various species of ants.Several studies looking at the diet of the four-teen different species of Phrynosoma havenoted that there appears to be a gradationin the percentage of ants eaten by each spe-cies. As part of study looking at the form andfunction of the feeding system inPhrynosoma we compared the relativemasses of all the jaw and hyolingual musclesin several species. A strong correlation ex-ists between the relative mass of the jawadductors and depressors and volume ofants eaten. Species such as P. Douglassi,which have large adductor mass, have alarger percentage of other insects in theirdiet. Whereas species with a higher per-centage of ants in the diet have smaller ad-ductors but larger jaw openers. This transi-tion appears to be a trade-off between be-tween a generalist and specialist diet. Largeradductors may allow generalists to processlarger, harder prey items. Ant specialists donot need to crush prey and it may be moreimportant to open the mouth quickly whencapturing small, fast prey. These observa-tions are supported by some preliminary ki-nematic and bite force data in two species.

P3.105A MEYLAN, S.*, CLOBERT, J., DEFRAIPONT, M., Université Pierre et MarieCurie-Paris 6. Maternal stress and juve-nile dispersal in the common lizard.

The causes of phenotypic variationamong individuals are of interest to manyscientists in Evolutionary Ecology. A phe-notype results from genetic and environ-mental influences. We are interested in theinfluences of maternal environment onphenotypic variation in natal dispersal.Offspring natal dispersal, as are other lifehistory traits, is influenced by prenatal en-vironment. An adaptive maternal controlof offspring behavior may promote off-spring fitness in temporally predictable en-

vironments. Conversely, maternal effectscould be maladaptive due to the time lagof the response to selection. In the com-mon lizard Lacerta vivipara, a suite of ex-periments has shown that maternal con-dition during gestation affects juvenile dis-persal, and we hypothesized that the con-dition of the mother reflects her own health(i.e. her future survival prospects) ratherthan the quality of the environment. Fur-thermore, Kin competition was shown tobe very important in shaping natal dis-persal in common lizards. To explore thishypothesis, we induced stress in pregnantfemales by application of corticosteroneand we measured dispersal and morphol-ogy of juveniles. No effect was found onmorphology. However, offspring dispersalfrom stressed mothers was decreased forlarge-sized (old) mothers, and increasedfor small-sized (young) females. So, fe-male age influenced the stress effect, andone can argue that corticosterone is notthe only factor affecting the developmentof the dispersal phenotype.

P1.75MIDDLE, L.B.*, BARNES, B.M, Uni-versity of Alaska, Fairbanks. Overwinteringstrategies of the wood frog, Rana sylvatica,in interior Alaska.

The wood frog, Rana sylvatica, is one ofthe most northerly distributed amphibianspecies with populations ranging up to 100miles north of the Arctic Circle. The key to itssurvival at high latitudes is the ability to sur-vive extracellular freezing of body tissues,an adaptation shared by only six species ofvertebrates. Laboratory studies of limits tocold tolerance of R. sylvatica have concen-trated on individuals from southern popula-tions from Ohio, USA and Ottawa, Canada.These studies determined a lower lethalbody temperature (50% survival) of -8oC andlimits to survival duration of freezing of ca.one month. Within the range of their distri-bution in Alaska, average ambient air tem-peratures range from -19.4oC to below -30oCfrom October to April, and soil-snow inter-face temperatures are regularly below -10oC,2oC below the lower lethal temperature.Wood frogs overwinter in terrestrial habitatswith individuals found within the leaf layer

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3-6 cm below the surface. Wood frogs inAlaska may survive prolonged freezing andminimum temperatures below lower lethaltemperatures known from southern popula-tions. Alternatively, Wood frogs in Alaska mayshare limits to freeze tolerance with south-ern populations and survive at high latitudesby finding hibernacula that are protected fromextreme temperatures. We explore poten-tial mechanisms of extended freeze toler-ance by determining hepatic glycogen andtissue levels of glucose in captive animalsbefore, during and after freezing to thesenew limits. This comparison adds insight asto whether Wood frogs in Interior Alaska dif-fer physiologically in their mechanisms offreeze tolerance from southern populations.In addition, we present temperatures expe-rienced by naturally hibernating Wood frogsin Interior Alaska.

P2.73MIDDLETON, K.M., Brown University,Providence RI. Influence of hallucal rever-sion on terrestrial locomotion in birds.

The reversed or opposable avian hallux(digit I) has been the subject of few anatomi-cal or functional studies. Primitively, thetheropod hallux was short and did not nor-mally reach the substrate during locomotion,while the reversed hallux of birds representsa subsequent elongation and rotation of digitI. It has been proposed that the presence ofa reversed hallux in a terrestrial theropodwould hinder over-ground locomotion and,therefore, would have evolved exclusivelyin an arboreal form. I recorded foot force out-put and center of pressure variation in theEuropean Starling (Sturnus vulgaris). Thehallux of the European Starling is large -approximately equal to the length of digit III -and is in contact with the substrate over thefull length of the digit. During most of the stridecycle, the center of pressure is located nearthe base of digit III, and the hallux contrib-utes significantly to the ground force of thefoot. A contrasting outcome would be ex-pected in a bird with a reduced hallux thathas less contact with the ground. Possibletradeoffs of hallucal reversion include alarger potential base of support and betterstability and increased mechanical advan-tage at the tarsometatarsal joint contrastedwith altered locomotor kinematics.

23.1 MILLER, L.A., Courant Institute ofMathematical Sciences, New Yo. A math-ematical model of insect flight: the immersedboundary method with fling.

Lift generation by insects at low Reynoldísnumbers has been a subject of great inter-est to some biologists, engineers, and math-ematicians over the past few decades. Un-fortunately, a realistic mathematical modelof insect flight, including a flexible wing mov-ing with three axes of rotation, has beencomputationally difficult to model. The im-mersed boundary method offers a reason-able approach toward modeling a flexible,moving boundary in a three-dimensionalfluid. In this presentation, results from a two-dimensional model of the clap and flingmechanism in Drosophila melanogaster willbe shown. These results include movies ofthe vorticity field over time and lift generatedover time for varying angular velocities andinitial angles between the wings during fling.Preliminary results from a three-dimensionalmodel of flight in Drosophila using experi-mentally determined flight kinematics withthree axes of rotation will also be presented.

S2.1 MINELLI, A., University of Padova. Ho-mology, limbs and genitalia.

Similarities in genetic control between themain body axis and its appendages havebeen generally explained in terms of geneticco-option. This extends to the parallels in thepatterning of arthropod and vertebrate ap-pendages, which have been explained ei-ther invoking a common ancestor alreadyprovided with patterned body outgrowths,or as the effect of independent recruitmentin limb patterning of single genes or geneticcassettes originally used for purposes otherthan axis patterning. I have suggest insteadthat these body appendages are evolution-arily divergent duplicates (paramorphs) ofthe main body axis. The same interpretationmay also apply to genitalia, irrespective ofwhether they are modified limbs, or directlyderive ex novo from a duplication of the mainbody axis. But, are all metazoan limbs andgenitalia homologous? Are limbs homolo-gous to genitalia (in vertebrates, or in otherphyla)? The answer to these question isnever a simple yes or no. The possibility foran animal to express a complex organ

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ectopically demonstrates that positional andspecial homology can be evolutionarily un-coupled. The concept of body appendages(limbs and genitalia) as paramorphs of themain body axis eliminates the requirementfor the last common ancestor of limb-bear-ing animals to have been provided withlimbs. Examples of a specified axial positionbeing alternatively used for genital and non-genital structures within the same phyluminclude a mid-body level hotspot correspond-ing to the millipede male gonopods, the drag-onfly secondary penis and the centipede“mid-body anomaly.” Also the transition frompaired to unpaired appendage (either limbor genitalia) is not necessarily large, as dem-onstrated by the insect genitalia (paired inmayflies, unpaired in the remainingpterygotes) as well as by the celacanth fins.

P3.22MINER, B.G*, MCEDWARD, L.R., Uni-versity of Florida, Gainesville. Diversity andevolution of larval patterns in holothuroidechinoderms.

Larval types and developmental patternshave been well studied in the echinodermclasses, asteroids and echinoids. In con-trast, the other classes of echinoderms,crinoids, holothuroids, and ophiuroids, havebeen ignored. We have reviewed the litera-ture on 69 species of holothuroids focusingon the phylogenetic distribution of develop-mental patterns and larval types within theclade. There are three observed larval types:auricularia, doliolaria, and vitellaria. Al-though not documented, facultativeplanktotrophy and a direct development mayexist. Phylogenetic distribution of these lar-val types suggests that the auricularia hasbeen lost 8 times, and that the vitellaria hasevolved 3-6 times within the group. The de-velopmental patterns that have been docu-mented are planktotrophy, pelagiclecithotrophy, and benthic lecithotrophy. As-suming a planktotrophic ancestor, the phy-logenetic distribution of these patterns sug-gests that brooding has evolved 6 timeswithin the holothuroids. In light of the fewstudies documenting developmental typeswithin holothuroids, the possible evolution-ary changes that can explain the observedtypes are complex. Future studies on devel-

opmental diversity, as well as a better un-derstanding of phylogenetic relationships,are necessary to elucidate the evolution oflarval patterns in this group.

P1.82MOFFETT, D.F.*, MOFFETT, S.B.,ROMERO, M.F., Washington State U., Wash-ington State U., Case Western ReserveMedical School. Immunolocalization of na+-dependent anion exchanger (NDAE1) inanterior stomach of mosquito larvae (Aedesaegypti): relevance to gut alkalinization.

A Na+-dependent anion exchanger(NDAE1) with homology to vertebrate bicar-bonate transporters has recently beencloned from Drosophila and expressed inXenopus oocytes.* In its orthograde modeNDAE1 mediates extrusion of Cl- and/or H+

in exchange for entry of Na+ and HCO3-.

NDAE1, like other bicarbonate transporters,is likely involved in both cytoplasmic acid-base homeostasis and transepithelial acidand alkali secretion. In these studies, fluo-rescence immunohistochemistry againstseveral conserved epitopes of NDAE1showed localization in anterior stomach (andother epithelia and CNS neurons) of mos-quito larvae. The anterior stomach gener-ates a luminal pH of ~10; the cellular mecha-nisms of this active alkali secretion are largelyunknown. In the anterior stomach, NDAE1immunoreactivity was abundant inbasolateral plasma membranes. This loca-tion is consistent with a model of alkaliniza-tion driven by tandem operation ofbasolateral Na+/K+ ATPase and electrogenicV-type H+ ATPase. The large electrochemi-cal gradient for Na+ created by these pumpswould provide the necessary ionic gradientsfor NDAE1, driving H+ from cell tohemolymph and HCO3

- from hemolymph tocytoplasm. Since NDAE1 also appears inapical cell membranes, and since mosquitolarvae ingest their very-low-Na+ freshwatermedium, it may function in the antigrademode in apical membranes, mediating cell-to-lumen movement of Na+ and HCO3

-.*Romero et al. (2000) J. Biol Chem. 275,24552.

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P2.45MOFFETT, S.B.*, MARTUS, J.M.,GELPERIN, A., Washington State University,Pullman, Washington State University, Pull-man, Bell Laboratories, Murray Hill. Ablationof a slug’s procerebral lobe blocks its abilityto discriminate water sources that are dan-gerous for rehydration.

Limax maximus, the common gardenslug, can experience dramatic reduction inbody water and then is highly motivated tofind a source of moisture for rehydrationthrough the body surface (Matanock andWelsford,1995). In nature, appropriatesources of moisture often have odors asso-ciated with them. Slugs sense odors prima-rily with their major tentacles, from which in-formation projects into a lobe of the braincalled the procerebral lobe. The procerebrallobe has been implicated in odor learning(Teyke and Gelperin,1999). In this experi-ment, we tested the hypothesis that slugscould be trained to associate odors withwater that was unsafe for rehydrating andthat this behavior might be missing in slugsthat lacked tentacles or the procerebral lobe.We dehydrated slugs and used three trials,spaced over 24 hours, to force them into con-tact with the dangerous (NaCl- and quinine-added), odor-laden (e.g., orange, cherry,pineapple) water for 2 min. After each dehy-dration and training exposure, we rehydratedthem in an odor free container. In the testsituation, 14 of 21 trained control slugschoose to rehydrate on a water source pairedwith a novel odor rather than in water pairedwith the odor previously associated with dan-gerous water. Slugs with the procerebrallobe ablated on one side and the tentaclecut off on the other side behave as if theycannot smell. Of 11 such operated slugs,trained and tested as described above, 7chose to rehydrate on the water source pre-viously paired with the dangerous water.These data and our behavioral observationssuggest that the combination of the unilat-eral procerebral lobe operation and con-tralateral sensory ablation can prevent theslugs from learning, perhaps by producinganosmia.

42.5 MONROY, J.A.*, NISHIKAWA, K.C.,Northern Arizona University. Aiming duringprey capture in microhylid frogs.

Microhylid frogs have the unusual abilityto aim their tongues independently of thehead during prey capture. The tongue iselongated hydrostatically, which requires anovel protractor muscle (m. genioglossus)morphology. This novel morphology anddemand for fine motor control raised thequestion: Are there unusual aspects to theinnervation of the tongue muscles inmicrohylids? Retrograde labeling of the hy-poglossal nerve revealed an exceptionallylarge number of motor neurons distributedmore caudally in the brainstem when com-pared to other anurans. In addition, dener-vation and EMG experiments have demon-strated that the m. genioglossus is the pri-mary muscle responsible for aiming thetongue within the Microhylidae. Thus, an in-crease in motor neurons may have resultedfrom an increase in the innervation of the m.genioglossus required to produce hydro-static elongation and aim the tongue. Thespeed of tongue protraction is highly vari-able between species (30 ñ 200 cm/s). Pre-liminary results suggest that microhylids withslower protraction speeds will have a largernumber of motor neurons innervating the m.genioglossus, which allows more controlover the tongue than microhylids that pro-tract their tongues at faster speeds. This hy-pothesis suggests a trade-off between thespeed of protraction and the degree of con-trol over the tongue in three dimensions. Thistrade-off may also reflect a frogís feedingstrategy and ecological niche.

9.1 MONTOOTH, K.L.*, CLARK, A.G.,MARDEN, J.H., Pennsylvania State Univer-sity, University Park. Physiological geneticsof flight performance in Drosophilamelanogaster.

Given the high demand that insect flightplaces on glycolytic metabolism, insect flightperformance should be particularly sensi-tive to the functional effects of allelic and regu-latory variation in energy metabolism. How-ever, the contribution of variation in energymetabolism to variation in flight performancehas yet to be quantified in a systematic man-

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ner, and the genetic basis for this variation isnot well characterized. Using a computer-ized tracking system, we quantified varia-tion in components of free-flight performanceamong genetically characterized lines of D.melanogaster. From frame-to-frame changesin three-dimensional location we calculatedpath velocity, acceleration and angular tra-jectory for individual flights. Differencesamong lines were found to be far greaterthan the variability among replicate flights offlies from the same line. Measures of ge-netic variation in components of free-flightperformance among 98 recombinant-inbredlines of D. melanogaster were used to con-struct a map of Quantitative Trait Loci (QTL).The QTL map revealed regions of the ge-nome that were significantly associated withvariation in flight performance. The relation-ship between variation in flight performanceand variation in metabolic rate, metabolicenzyme activity, and glycogen andtriacylglycerol concentration was investi-gated using multiple regression models. Theextent to which regions of the genome ex-hibited pleiotropic effects on multiple meta-bolic traits will also be discussed. This quan-titative genetic approach gives us insight intowhat might be the genetic response to se-lection on whole organism physiologicalperformance. Supported by NSF and HHMI.

26.5 MOON, B.R.*, URQUHART, M.R.,CONLEY, K.E., University of Washington,Seattle, Northern Arizona University, Flag-staff, University of Washington, Seattle. Invivo shortening in the superfast tailshakermuscle of rattlesnakes.

Sound-producing muscles typically con-tract at high frequencies with minimal short-ening. The tailshaker muscle of western dia-mondback rattlesnakes (Crotalus atrox) con-tracts at frequencies of 20-100 Hz and has aconstant energetic cost per twitch, but its ex-tent of shortening is unknown. Decreasinglateral displacement of the rattle with in-creasing twitch frequency suggests that themuscles shorten less at higher twitch fre-quencies. However, the constant cost pertwitch suggests that muscle shortening isconstant. We are using sonomicrometry tomeasure muscle shortening in vivo and to

test three factors that may account for theapparent discrepancy between muscle en-ergetics and mechanics: (1) A tradeoff be-tween lateral and torsional rotation of therattle with increasing twitch frequency mayinvolve a tradeoff in shortening among thethree groups of tailshaker muscles. (2) Theextent of eccentric contraction may vary withtwitch frequency, which could change theforce and displacement per twitch with mini-mal or no change in cost. (3) Rattle motionmay be ballistic, with the maximal displace-ment being limited by the timing of contralat-eral twitches rather than by the extent of ac-tive muscle shortening. Preliminary resultsindicate that all three factors are important.Quantitative analysis, now under way, mayshow how each factor contributes to changesin muscle and rattle mechanics withoutchanging the muscle energetics.

S9.9 MOORE, F.L.*, Oregon State Univer-sity. Ultimate and proximate mechanismsthat control the stress-induced inhibition ofreproductive behaviors.

When animals confront harsh or threat-ening conditions, they frequently respondwith rapid changes in behavior, for example,switching from courtship behavior to survivalbehaviors such as hiding or fleeing. Stresshormones regulate this shift in behavioralstate. Behavioral studies in an amphibianmodel, the roughskin newt (Taricha granu-losa), demonstrate that acute stress triggersthe secretion of corticosterone and that theelevated corticosterone concentrationcauses a rapid suppression of reproductivebehaviors. This behavioral response to cor-ticosterone works through a non-genomicpathway that involves a membrane-associ-ated corticosteroid receptor (mCR) in the G-protein coupled receptor superfamily(Orchinik et al., 1991). The mCR protein hasan apparent mass of 63 kDa (Evans et al.,2000a). The mCR binding site is highly se-lective, recognizing only two steroids (corti-costerone and cortisol) and a subset ofkappa-selective ligands (Orchinik et al.,1991; Evans et al. 2000b). These binding dataare consistent with behavioral and physi-ological studies showing that corticosteroneand specific kappa ligands trigger similar

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responses. Our working hypothesis is thatthe mCR is structurally related to a kappaopioid-like receptor. (Supported by NSF grantIBN 9319633)

P3.97MOORE, I.T.*, WINGFIELD, J.C., Uni-versity of Washington. Latitudinal gradientin sensitivity of the hypothalamic-pituitary-gonadal axis to gonadotropin-releasing hor-mone.

Field investigations have revealed com-plex patterns of testosterone levels in verte-brates. Even in closely related taxa andwithin populations (especially birds) patternsof testosterone secretion may be dramati-cally different. The mechanisms underlyingthis variation in patterns remain unclear. Atthe secretion level, differences in plasmatestosterone levels could result from differ-ences in activity or sensitivity of the hypo-thalamic-pituitary-gonadal (HPG) axis. To ad-dress this we challenged birds from differ-ent latitudes with similar doses of gonadot-ropin-releasing hormone (GnRH) and mea-sured resulting plasma levels of testoster-one. If bird populations respond similarly tothe GnRH challenge then observed differ-ences in plasma testosterone may be theresult of differences in activity of the HPGaxis. If bird populations respond differentlyto the GnRH challenge then observed dif-ferences in plasma testosterone may be theresult of differences in sensitivity of the HPGaxis. We performed the experiment in twopopulations of white crown sparrows: thehigh latitude breeding Gambleís white crownsparrow (Zonotrichia leucophrys gambelii)in Toolik, Alaska and the mid latitude breed-ing Puget Sound white crown sparrow (Z. l.pugetensis ) from Washington. Birds werecaptured and received a 500ng of GnRHand a blood sample obtained either 10 or30 minutes later. GnRH treated birds fromboth populations had significantly higherplasma levels of testosterone after 30 min-utes that was not evident at 10 minutes postinjection. There was no difference in the re-sponse between the mid and high latitudepopulations of birds. We are currently ex-tending this study to a low latitude popula-tion of rufous-collared sparrow (Z. capensis)in central Ecuador.

15.4 MOORE, M.C.*, PAINTER, D.,WOODLEY, S.K., LACY, E.L., JENNINGS,D.H., WIKELSKI, M., Arizona State Univer-sity, Tempe, Arizona State University, Tempe,Boston Univ, Boston, Arizona State Univer-sity, Tempe, Arizona State University, Tempe,Princeton University, Princeton. Neuroendo-crine mechanisms of alternative male repro-ductive tactics in marine iguanas.

Alternative male phenotypes often dif-fer as much in appearance and behavioras do males from females. These extremeexamples of within-sex variation are goodmodels to examine neuroendocrine basesof such variation. The relative plasticity hy-pothesis (RPH) generalizes the organiza-tion-activation model of sexual differentia-tion to within-sex variation. It proposes thatspecies with fixed alternative male mor-phs will have developmental (organiza-tional) mechanisms of differentiationwhereas species with plastic alternativemale morphs will use activational mecha-nisms. In this study, we examined marineiguanas (Amblyrhynchus cristatus), whichhave a complex system of plastic alterna-tive male phenotypes: there are 3 distinctmorphologies and 5 distinct social classes.Since males transform types as they age,the RPH predicts that there will be hor-monal mechanisms operating at the timeof transformation. Comparison of testoster-one (T) levels in free-living males from theGenovesa Island population partially con-firms this prediction. Males of the twononterritorial classes had T levels lowerthan those of males in the two successfulterritorial classes. Furthermore, when sub-jected to 30 minutes of handling stress,nonterritorial males increased their T lev-els whereas successful territorial malesdid not. Unsuccessful territorial maleswere intermediate. These results contrastwith those from species with fixed systemsand suggest that activational neuroendo-crine mechanisms are important in plasticalternative male phenotypes of marineiguanas.

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P1.34MOORE, M.M.*, White, J.V., WILL-IAMS, E.E., Salisbury State University.Docosahexaenoic acid in cell membranes:vital for fish and fatal for cancer.

It is known that cells from fish main-tained in cold water contain much higheramounts of docosahexaenoic acid (DHA)than cells of the same fish at warmer tem-peratures. DHA is also associated with thealleviation of many human diseases. In ad-dition, it severely inhibits the growth of tu-mor cells. In all of these cases, there isevidence that the incorporation of DHA intocellular membranes is the common bondbetween these events. Thus, there seemsto be a dichotomy of consequences to thepresence of DHA in cellular membranes.Our research is focused on why DHA islethal to tumor cells and beneficial to cold-water fish. We cultured murine leukemiacells (T27A line) at 37ƒC in various con-centrations of DHA and measured prolif-eration rates and cell viability in order toverify the anti-cancer properties of DHAon this cell line. At concentrations below150 mg/mL, DHA had no effect on eithervariable. At concentrations above 150 mg/mL, a significant reduction in both of theseparameters was observed. For example,after four days of culture at 300 mg/mLDHA, only 22% of the cells present re-mained viable and cell numbers fell dra-matically. Cells grown in the presence ofoleic acid at the same concentrations andlength of time grew at the same rate ascontrol cells. These data confirm the sen-sitivity of this cell line to the anti-cancereffects of DHA. Currently, two sets of ex-periments are underway. The first set in-volves repeating the experiments on cellscultured at 27ƒC, a temperature decrease(10ƒC) known to cause an increase in thelevel of DHA in the membranes of fish cells.The second set uses fluorescent micros-copy to determine the mode of death in-duced by DHA (apoptosis or necrosis).Combined, these data will allow us to as-sess the interdependence of DHA and tem-perature as it relates to cell survival.

25.5 MOORE, A.M.F.*, CHIU, H.,LAWRENCE, B.A., Universityof the Pacific,Stockton, Ca, University of the Pacific, Stock-

ton, Ca, Eastern Illinois University Charles-ton. Mechanical characterization of egg casesilk in the black widow spider (Latrodectushesperus).

Silk from egg case of the black widowspider (Latrodectus hesperus) differs inamino acid composition from the animal’sdragline silk. Because the primary functionof an egg case is non-load bearing, we ex-pected that the molecular differences in thetwo silks might lead to differences in theirmaterial properties. To test this hypothesis,we stretched egg-case silk to breaking andcompared the resulting stress-strain curveto the stress-strain curve of the animal’s dra-gline silk. The two curves are similar in thatthey both have an initial linear region, fol-lowed by a yield point and then a second,less stiff, linear region. The presence of ayield point suggests a conformationalchange in the protein that, in turn, changesthe way the molecular interactions resist theload as the silk is stretched. The two silksare also similar in strength and in the stiff-ness of the initial linear region of the curve.However, they differ in that (1) egg case silkis twice as extensible as dragline silk, (2) itsyield point occurs at about three times higherstrain and (3) after the yield point, egg casesilk is almost an order of magnitude less stiffthan dragline silk. We used carbon-13 solidstate NMR spectroscopy to look at the sec-ondary structure of the silk proteins. Thespectra show that the alanine in both dra-gline and egg case silk is in beta-sheet con-formation. This is consistent with the pres-ence of alanine-rich beta-sheet crystalscommonly found in silks. The spectra alsoconfirm the presence of a large amount ofserine in the egg case silk that is not presentin dragline silk. It is possible that serine af-fects the non-crystaline region of the mol-ecule to cause the observed differences inbulk properties. (NSF DBI-9996072).

23.4 MORENO, C.A.*, TU, M.S., DANIEL,T.L., University of Washington, Seattle. Vi-sual-motor feedback in the tracking behav-ior of hovering Manduca sexta.

Insight into the complex interplay of sen-sory information, musculoskeletal mechan-ics, and aerodynamic forces is critical for un-derstanding the fundamental determinants

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and limits of insect flight performance. Whilefeeding at flowers in the wind, hovering hawk-moths must track a moving target in a spa-tially complex environment. Although the vi-sual system can discriminate motion in dif-ferent directions, characteristcs of the mus-culoskeletal system could constrain the pre-cision of directional control (eg., by introduc-ing ‘crosstalk’ into control pathways). More-over, frequency tuning in the visual systemmay be insufficient to account for the fre-quency response of tracking behavior at theorganismal level. To understand the con-straints that emerge from sensorimotor inte-gration, we used 30Hz video to record hov-ering moths as they fed at artificial flowers.We oscillated the flowers sinusoidaly at 1,2,and 3 hz, and three amplitudes (~ 1, 2, 3 cm)for motion in the x- (looming), y- (vertical),and z-(lateral) directions. For each feedingbout, we calculated the gain of the moths’tracking behavior as the amplitude of mothmotion relative to flower motion at the driv-ing frequency. For all three directions, thegain was lowest at 3hz. Tracking behavior,however, had the greatest match of animalmotion to flower motion at 2 hz for both loom-ing and lateral motions. Moreover, there isstrong coupling between these componentsat all frequencies. The peak in tracking abil-ity is consistent with predictions from mod-els of motion detection. Our data, therefore,show a close alignment of whole organismdynamics with retinal and neuronal process-ing. (NSF IBN9511881, ONR to C. Diorio).

37.2 MORGAN, S.M.*, ASHLEY-ROSS,M.A., ANDERSON, D.J., Wake Forest Uni-versity. Incubation in masked boobies.

Lacking brood patches, masked boobies(Sula dactylatra) incubate eggs with theirwebbed feet. No studies to date have ex-amined incubation temperature in maskedboobies. Incubation temperatures weretracked for individual masked boobies nest-ing in a colony on the island of Espanola,Galapagos, Ecuador. Plastic Easter eggs,identical in size to actual eggs, containingwater and a temperature data logger torecord egg temperature, were sealed withwhite acrylic paint to more closely resemblenatural eggs. Natural eggs in four, one-egg

clutch nests were replaced with data loggereggs. Birds were allowed to incubate thelogger eggs for 3 days. This procedure wasrepeated 13 times for a total of 52 nests. Allegg temperatures remained above ambienttemperature during incubation. Over the 3-day interval, mean egg temperatures were37ƒC (range: 2 - 3ƒ), while ambient tem-perature fluctuated cyclically throughouteach 24-hour period from 22ƒC to 35ƒC. Pre-liminary data with isolated thermocouplessuggest that boobies added heat for incu-bation through the webs of their feet.

53.3 MORRIS, K.A.*, KARASOV, W.H.,CAVIEDES-VIDAL, E., University of Wiscon-sin, Madison, University of Wisconsin, Madi-son, Universidad Nacional de San Luis, Ar-gentina. Does digestive physiology limit re-fueling rates in migratory yellow-rumpedwarblers (Dendroica coronata)?

Smaller guts and slow initial mass gainsin migrating birds at stopover sites have ledto the idea of a digestive limitation to refuel-ing in migrants. We tested the digestive limi-tation hypothesis in yellow-rumped warblersusing food restriction to simulate infrequentfeeding during migration, which may causea reduction in alimentary tract mass. We pre-dicted that following three days of food re-striction (ca. 50% ad libitum intake): 1) di-gestive organ masses would decrease, 2)digestive capacity as measured by diges-tive enzyme activities would decrease, and3) previously restricted birds would not beable to feed and digest at a high rate imme-diately following return to ad lib. feeding. Inour tests of these predictions, restricted birdshad small intestine, pancreas, and livermasses 18-22% lower than ad lib.-fed con-trols. Total activities of sucrase, maltase, ami-nopeptidase, and amylase were significantlylower (by 37-48%) in restricted birds than incontrols, while those of trypsin and chymot-rypsin were not. Mass-specific activities didnot differ significantly between groups ex-cept for aminopeptidase, which was lowerin restricted birds. Contrary to our prediction,previously restricted birds were able to feedand digest at a significantly higher rate thanthe controls immediately following return toad lib. feeding. Digestive efficiency did not

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differ between groups. These results sug-gest that prior to migration yellow-rumpedwarblers have greater than 20% spare di-gestive capacity to compensate for declinesin their digestive organ masses during mi-gration.

68.2 MORSE, M.P., University of Washing-ton. AIBS/Packard review of high school bi-ology instructional materials.

Ten sets of instructional materials cur-rently used in high school biology coursesacross the nation were reviewed by a 9-person team of scientists, science educa-tors and teachers. This team developedthe AIBS/Packard review instrument andconducted the review over a period of 18months. The review instrument is basedon the National Science Education Stan-dards (NRC), and on parts of Benchmarks(AAAS,2061).Each set of materials re-ceived six independent reviews, two ineach of the three biology content areas.Scores from 3 discipline content areas, mo-lecular genetics, evolution and interdepen-dence of organisms were combined withscores relating to other content standardsand pedagogical considerations such asactive learning, inquiry and assessment.Results indicate authors and publishershave begun to address the standards in avariety of ways. Some add numerous ac-tivities, visuals, concepts and facts to tra-ditional text materials. Others utilize coreunits with flexibility built in with additionalmaterials for teachers to teach conceptsof choice. Other materials utilize innova-tive changes in instructional design.Choosing materials is a responsibility; in-volving teachers, parents, scientists,school boards, superintendents, state se-lection committees and others; we providethese stakeholders with an accountableindependent review of the spectrum ofavailable materials. The goal is to helpthose who choose curricular materials forthe nationís classrooms with a basis formaking informed decisions. Results arevariable, some meeting content standards,some meeting content and assessmentstandards, and some meeting content,pedagogical, assessment and profes-

sional development standards. Teachersneed materials that meet the national stan-dards and engage all students in opportu-nistic learning environments to become lit-erate in biology.

P3.59MOSHEL-LYNCH, S.*, COLLIER, J.,University of California, Berkeley, Effie Labo-ratory. Conservation of mesodermal-specificgenes in molluscs.

While bilateral symmetry is the ancestralstate of molluscs, the gastropods haveadopted various developmental pathwaysleading from bilateral symmetry to complexasymmetrical body plans. Because many ofthe asymmetrical organ systems are meso-dermal derivatives the identification of me-sodermal regulatory genes is essential forunderstanding how the molluscs diversified.It has been well demonstrated that Twist andSnail play a significant role in both determi-nation and differentiation of mesoderm in avariety of organisms. Thus, using the poly-merase chain reaction we have identifiedthese two genes in the genomes of variousmolluscs. By in situ hybridization and Immu-nocytochemistry we have detected the ex-pression of Twist and Snail in mesodermallineages of the marine mud snail Ilyanassaobsoleta. We have also found that both ofthese genes are maternally expressed.Throughout the animal kingdom there are avariety of different mechanisms for meso-derm formation, and our study of teloblasticmesoderm formation in a spiralian embryoextends the body of evidence for the con-servation of genes used for mesoderm for-mation. This body of evidence illustrates ge-nomic antiquity in the face of developmentaldiversifiction.

3.5 MOTANI, R., Royal Ontario Museum.Using models of extant swimmers to inferaspects of locomotion in thunniform ichthyo-saurs.

Studying the functional morphology ofextinct vertebrates poses challenges be-cause only fossil remains are available.Robust correlations among certain physical,physiological, or kinematic variables in ex-tant vertebrates can help infer functionalparameters of extinct animals. I present a

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case where such correlational approachesprove useful in estimating some swimmingcharacteristics of extinct marine reptiles. Ich-thyosaurs (250 to 90 million years ago)evolved a tuna-like body shape from a liz-ard-like body plan of their ancestors, andsome well-preserved specimens of the ge-nus Stenopterygius, for example, show theoutlines of lunate caudal fins. I used twocorrelations observed among living swim-ming vertebrates to estimate optimal swim-ming speeds in Stenopterygius (0.5 to 2.5 mfork length). The first set of estimates wasbased on the scaling of caudal fin kinemat-ics observed in thunniform, carangiform, andsubcarangiform swimmers. The second setwas derived from the commonly used ener-getic model of constantly swimming verte-brates. The first estimates showed an almostidentical distribution to the second set, pro-viding some confidence in the results ob-tained, and suggesting that Stenopterygiuscruised more slowly than delphinids of simi-lar body size. The two estimation methodswere tested by applying them to extant swim-ming vertebrates, prior to the application toStenopterygius. The methods successfullyapproximated the optimal speed values inthe literature (based on speed vs. oxygenconsumption data). These results hold thepromise of testable quantifications of somegeneral performance variables in extinctswimming vertebrates, and of more accu-rate characterization of their functional andecological modes of life.

51.1 MOTZ, A.M., WOLCOTT, T.G.*,WOLCOTT, D.L., HINES, A.H., NC State Uni-versity, Raleigh, NC State University, Ra-leigh, NC State University, Raleigh,Smithsonian Env. Research Ctr., EdgewaterMD. Sperm limitation and operational sexratio in blue crabs.

To understand whether the intense fish-ery on male blue crabs (Callinectes sapidus)is leading to sperm limitation and reducedreproductive potential in Chesapeake Baypopulations, we are investigating whetherthe number of males, or their adequacy asmates, is diminished. A long-term S.E.R.C.trawl data set is being analyzed for evidencethat the male:female ratio has changed his-

torically. We have developed biotelemetrysystems for free-ranging crabs to measurelatencies to pairing and mating for each gen-der, as well as to reveal where these activi-ties occur and thus where operational sexratio should be measured. We are collect-ing crabs engaged in pre- or post-copula-tory mate guarding (“doublers”) from the field.Many small males are mating, even thoughthey could be displaced if large ones werepresent. A large proportion of the males inthe Bay is severely sperm-depleted. Largemales caught as “doublers” often possessand deliver no more seminal resources thando small ones, even though we would ex-pect them to deliver much more if they were“fully-recharged”. The most-depleted malesare not found as “doublers” and apparentlyare not mating. This indicates that the op-erational sex ratio is lower than suggestedby the numerical ratio of adult males to pu-bertal females. Even if a proportion of themales that escape the fishery is not mating,the remaining number seems adequate toprovide almost all females with at least somesperm during their single brief opportunityfor mating. The concern is whether it isenough to fertilize their potential egg output;many of those males are small or have par-tially-depleted sperm stores.

P1.99A MUELLER, P.J.*, STEYER-MARK,A.S., UCLA School of Medicine. Constraintof small cages turns California mice intocouch potatoes.

Although care is taken in maintainingproper temperature, lighting and feedingregimes for captive experimental animals,other facets of husbandry that can influenceexperimental results may be overlooked. Forexample, investigators routinely place ani-mals in whatever size of cage they have athand that seems remotely reasonable. Wequestioned whether the size of the cage inrelation to the size of the animal may affectphysiological variables. We measured 24-hour energy expenditure (VO2) and ten dayfood intake in two species of Peromyscusmice that differed in body size: largePeromyscus californicus (body mass 45-55g) and small P. eremicus (22-26 g). In a two-period cross over study, mice were individu-

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ally housed in both small (25x15x12cm) andlarge (40x25x20cm) cages. While VO2 andfood intake of small mice (P. eremicus) wereunaffected by cage size, VO2 of large mice(P. californicus) was less when placed in asmall cage compared to a large cage, de-spite the fact that the small cage size waswithin normal animal care guidelines.Californicus mice also ate less food whenhoused in small cages, but not enough lessto offset their reduced energy expenditureand consequently body mass increasedslightly. In large cages, we observed allmice frequently jumping and flipping; smallcages did not afford sufficient room for largemice to jump and hence they likely spentmore time stationary. Small mice were notsimilarly constrained. Our data suggest thatmore care needs to be given to consider-ations of size and type of animal housing,otherwise measurements thought to be un-biased may be reflecting factors other thanapplied treatments. In our case, choice ofcage was unimportant when studying thesmaller species, but could skew results forlarger mice.

49.1 MUELLER, R.L., Museum of Verte-brate Zoology, UC Berkeley. Who needs anucleus? Red blood cells in the genusBatrachoseps.

Some species of lungless salamanders,family Plethodontidae, have blood contain-ing enucleated red cells. Unlike nearly allmammals, which possess uniformly enucle-ated RBCís, these salamanders have bothenucleated and nucleated RBCís presentin their circulation at all times. In some cases,the percentage of enucleated red cells is ashigh as 99%. Despite its unique status amongnon-mammalian vertebrates, this blood con-dition has been relatively unstudied. Initialreports (Eisen, 1897) of the enucleated con-dition were from two species ofBatrachoseps. In recent years, analysis ofmorphological and molecular data hasshown Batrachoseps to be comprised ofover twenty species, many as yetundescribed, with high levels of genetic di-vergence. Villolobos et al (1988) examinedthe blood of four species of Batrachoseps,two from each of the major clades (subgen-

era). Their results showed that species nowassigned to the subgenus Batrachosepshave a high percentage of enucleated eryth-rocytes, while species of the subgenusPlethopsis have a low percentage of enucle-ated erythrocytes. A full understanding ofthe evolution of enucleated red cells muststart with knowledge of the relative abun-dance of these cells in all extant members ofthe genus, coupled with a robust phyloge-netic hypothesis. To this end, I examined theblood of ten individuals from each of twentyspecies. Results for the subgenus Plethopsisagree with previous reports; specimens havelow numbers of enucleated cells. However,members of the subgenus Batrachosepsdisplay substantial variation in numbers ofenucleated cells. This variation exists bothamong different species and within a singlespecies, and raises questions of ontogeneticand environmental effects on blood compo-sition.

P2.64MULLER, U.K.*, STAMHUIS, E.J.,ELLINGTON, C.P., University of Cambridge.Quantifying the leading-edge vortex of ahovering robotic insect during thedownstroke.

A hovering hawkmoth Manduca sextagenerates a stable leading-edge vortex dur-ing the downstroke. To study the flow ingreater detail, a scaled-up robotic model thatmimics the wing movements was built (theflapper). The flow around its wings wasvisualised with neutrally buoyant soapbubbles and mapped using three-dimen-sional particle tracking velocimetry. Our re-cordings confirm earlier findings obtainedfrom qualitative smoke flow visualisation(van den Berg and Ellington, 1997): a coni-cal leading-edge vortexdevelops during thedownstroke, with a strong spanwise com-ponent from the wing base to the wing tip. At75% wing length, the leading-edge vortexbends towards the trailing edge and feedsinto the tip vortex. While the vortex is stillattached and close to the leading edge itsdiameter increases five-fold and thespanwise flow accelerates from 1 to 5 ms-1.Computational flow fields around a hover-ing hawkmoth (Liu and Kawachi, 1998) sug-gest that late in the downstroke a second

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leading-edge vortex develops with aspanwise flow towards the base rather thanthe tip of the wing. This vortex was not ob-served in the previous flow visualisationstudy (van den Berg and Ellington, 1997) orin the present experiments, which employeda smoother wing surface, leading edge, andcamber. References: Van den Berg C. andEllington C.P. (1997) Phil. Trans. R. Soc. Lond.B 352, 329-340. Liu H. And Kawachi K. (1998)Journal of Computational Physics 146, 124-156.

P3.96MURDOCK, C.*, WIBBELS, T., Univer-sity of Alabama at Birmingham. Use of a quan-titative competitive RT-PCR to evaluatearomatase expression in a turtle.

The red eared slider turtle, Trachemysscripta, possess temperature-dependentsex determination (TSD). Previous studieswith T. scripta have suggested that steroids,in particular estrogens, may play key rolesin the sex determination cascade. Therefore,steroidogenic enzymes involved in the syn-thesis of estrogens are of particular interest.Previously in our laboratory the cDNA forone such steroidogenic enzyme, aromatase,has been cloned and sequenced from T.scripta. Using this sequence data, a PCR-based strategy was employed in the con-struction of an RNA competitor molecule foraromatase. The synthesis of this RNA com-petitor facilitated the development of a quan-titative competitive RT-PCR (QC RT-PCR) foraromatase. In the current study, we havevalidated and begun utilizing this QC RT-PCR. Preliminary results have shown that:(1) When competitor RNA was added to to-tal RNA extracted from tissues, both co-am-plified. (2) Varying the amount of competitorwhile leaving the amount of total RNA addedto each tube constant results in varying in-tensity in the competitor bands, while theintensity of the endogenous target band re-mains constant. (3) By varying the amount ofcompetitor added to each sample tube, astandard curve of intensity can be gener-ated, by which aromatase expression dur-ing TSD can be quantified. We are now us-ing this QC RT-PCR to examine the expres-sion of aromatase during TSD. QC RT-PCRsare currently being performed on total RNA

isolated from adrenal-kidney-gonadal com-plexes taken from embryos incubated at bothmale and female-producing temperatures(26OC and 31OC respectively) at stages 15,17, 19, and 21 of embryonic development.The results will provide a chronology ofaromatase expression during TSD.

P1.91MYKLES, D.L.*, MULDER, E.P.,MEDLER, S.A., CHANG, E.S., ColoradoState University, Bodega Marine Lab, Colo-rado State University, Bodega Marine Lab.Developmentally-regulated fiber-typeswitching in claw muscles of American lob-ster, Homarus americanus.

Fibers in the claw closer muscles un-dergo a developmentally-regulated switch-ing as the isomorphic claws of larvae andjuveniles differentiate into the heteromorphiccutter and crusher claws of the adult. Fast-to-slow switching occurs in the presumptivecrusher claw and slow-to-fast switching oc-curs in the presumptive cutter claw. This fi-ber switching occurs at the boundary be-tween the central fast-fiber and the periph-eral slow-fiber regions, and thus the switch-ing of a specific fiber is determined by itsposition within the muscle. We have clonedcDNAs encoding fast-type isoforms of myo-sin heavy chain (fMHC), P75 regulatory pro-tein (P75), and tropomyosin (fTm) and slow-type isoforms (sMHC and sTm1) to use asmolecular markers for switching. The expres-sion of myofibrillar protein isoforms duringthe intermolt cycle was determined usingRNA blot analysis and in situ hybridization.Switching fibers were identified as those fi-bers expressing both fast and slow tran-scripts. Switching occurred in the postmoltperiod, during which accelerated proteinturnover facilitates incorporation of newly-synthesized protein into the contractile ap-paratus. Supported by NSF (IBN 00-77422).

S1.8 NARINS, P.M.*, LEWIS, E.R., Univer-sity of California, Los Angeles, University ofCalifornia, Berkeley. Good vibrations: seis-mic signal use by fossorial mammals.

Low-frequency seismic vibrations areknown to travel across the surface of theearth, a medium relatively free from back-ground noise. In recent years, seismic sen-

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sitivity has been recognized as an importantsensory modality in fossorial mammals.Consistent with this idea, it has been experi-mentally demonstrated that seismic signalsare propagated at least an order of magni-tude better than airborne signals betweenthe natural tunnels of the South African Capemole-rat, Georychus capensis. Indeed, low-frequency seismic signals are generated byfoot- and head-drumming in many fossorialrodents. It has been proposed that the “seis-mic communication modality may be themajor long-distance communication chan-nel in the evolution of [the mole-rat Spalax]and possibly in subterranean mammalsgenerally”. Evidence is accumulating to in-dicate that certain fossorial mammals, as inthe case of frogs, may use the auditory sys-tem to detect seismic signals. Geophoneand microphone measurements in the sandsuggest that the Namib Desert golden mole(Eremitalpa granti namibensis) is able todetect termite colonies and other prey itemsusing seismic cues from distances up to 20m, presumably aided by its hypertrophiedmalleus and the low substrate backgroundnoise level. We here review the evidencefor the use of seismic signals by subterra-nean mammals and discuss putative mecha-nisms underlying their detection.

2.5 NAUEN, J.C.*, LAUDER, G.V., HarvardUniversity. Small-scale flow around the finletsand caudal peduncle of free-swimming chubmackerel (Scomber japonicus).

The trajectory and speed of flow in thevicinity of the finlets (small fins on the dorsaland ventral body margin anterior to the cau-dal fin) and caudal peduncle of chub mack-erel (Scomber japonicus) swimming steadilyin a flow tunnel at 1.2 lengths/s were deter-mined by particle tracking. Small, reflectiveparticles in the water were illuminated by avertical (xy) or horizontal (xz) light sheet pro-duced by a 5W argon-ion laser; images ofthe flow were recorded at 250 Hz using atwo camera NAC HSV 500 video system. Atotal of over 800 particles were tracked for atleast 12 ms for four tail beats from each offour fish 20 - 24 cm in length. Particles vis-ible in the xz light sheet approximately 3 mmbelow the ventral body surface were tracked

for up to 40 ms, indicating strong horizontalflow. As the tail decelerates, the most poste-rior finlet achieves an angle of attack of atleast 20o to incident flow indicating lift pro-duction and vortex formation. In the xy lightsheet the trajectory of particles on the leftside of the fish above and below the bodymidline were significantly different when thefinlets were present and the tail was decel-erating to the right than when the finlets wereabsent and the tail was decelerating to theleft. On average, when finlets were presentand the tail was decelerating to the right thetrajectory angle of particles above the bodymidline decreased from –3 to –10o relativeto the horizontal, and the trajectory of par-ticles below the body midline increased from–2 to 16o, indicating the creation of conver-gent flow. These data are consistent with thehypothesis that finlets increase the flow di-rected into the caudal fin vortex, and thusincrease the thrust produced by the tail ofthe swimming mackerel.

4.3 NAUWELAERTS, S.*, AERTS, P., Uni-versity of Antwerp, Belgium. Gait patterns infrog locomotion: why use alternate-leg swim-ming?

During terrestrial locomotion, frogs usetwo different gaits: asynchronous leg move-ments associated with slow crawlingbahaviour and synchronous leg movementsduring fast jumps. In Rana esculenta crawl-ing occurs during feeding, while jumping isused as an escape strategy. We examinedwhether a similar velocity-dependent gaittransition appears in swimming R. esculenta.Typically, swimming frogs propel themselvesby kicking both hind limbs simultaneously.Observations of asynchronous leg move-ments in swimming frogs have been re-ported, but usually were assumed to be as-sociated only with directional changes. Wedemonstrate that alternating-leg swimmingis used quite frequently and that it results ina significantly lower velocity to that obtainedusing synchronous leg movements. This dif-ference is likely to be associated with ener-getic costs. External mechanical costs forasynchronous swimming were only half ofthose for synchronous swimming at a com-parable speed. However, asynchronous

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swimming at speeds higher then 0.19 m/swas never observed. Although energy re-quirements for asynchronous swimming arelower, at high speeds asynchronous swim-ming is apparently never applied. Possibleexplanations for this phenomenon arehigher inertial energy losses for synchro-nous swimming, but at high speeds jet pro-pulsion and an interaction effect may be-come important.

S7.9 NEAR, T.J., University of California,Davis. Phylogeny of the Acanthocephala andinsights to the evolution of parasitism.

The Acanthocephala are a lineage ofobligate helminth parasites of arthropods andvertebrates. Previous phylogenetic investi-gations utilizing ribosomal and protein cod-ing genes indicate that the Acanthocephalais nested within the Rotifera. This is the onlymajor parasitic lineage with an indentifiedfree-living sister-taxon. This recovered phy-logenetic relationship permits critical exami-nation of several hypotheses concerning theevolution of parasitism in metazoans. Thehypothesis that the Acanthocephala aremodified rotifers has been questioned. Theevidence for this hypothesis is reviewed andboth total evidence and consensus ap-proaches are utilized in a phylogenetic re-analysis of the extant morphological andmolecular data. Potential confounding vari-ables in the phylogenetic analyses are pre-sented. For example, alignment of the 18SrRNA dataset is problematic. The issue ofhomology assessment is discussed in rela-tion to previous investigations and recogni-tion of rRNA secondary structure. Revisedphylogenetic analyses of relationships withinAcanthocephala are used to test the validityof recognized taxonomic groups, characterevolution within and among lineages, anddiversification of hosts and habitats. The re-sults of phylogenetic reanalysis of acantho-cephalan affinities, in relation to the Rotifera,are utilized to examine the evolution of para-sitism in the Acanthocephala. The resultsfrom this examination provide a critical testto several long-standing hypotheses con-cerning the evolution of parasitism in meta-zoans.

P3.24NEDERBRAGT, A.J.*, LESPINET, O.,DICTUS, W.J.A.G., VANLOON, A.E.,ADOUTTE, A., VANDENBIGGELAAR,J.A.M., Utrecht University, Netherlands, Cen-tre de Genetique Moleculaire CNRS,France, Utrecht University, Netherlands,Utrecht University, Netherlands, Centre deGenetique Moleculaire CNRS, France,Utrecht University, Netherlands. Twist andsnail homologues in the gastropod molluskPatella vulgata: a new twist for an old genenetwork?

Mesoderm development must have beencrucial in the evolution from diploblastic intotriploblastic animals. To obtain a reliable in-sight into the evolution of the mesoderm weurgently need information about the molecu-lar control of mesoderm in other phyla. Ourgroup is interested in the molecular aspectsof mesoderm formation in Spiralia. As thetwist-snail gene network is known to specifymesoderm in a number of animals, it is inter-esting to know whether its function in Spiraliasuch as Molluscs and Annelids is conserved.As a starting point we chose a primitive gas-tropod mollusk, Patella vulgata. We haveobtained two Patella orthologues of Snail,and a fragment of the orthologue of Twist.The results of in situ hybridization experi-ments for Snail are very intriguing, as no dis-tinct mesodermal expression for either of theSnail orthologues has been observed. Thepattern we see indicates expression insidethe future head region, in the developingmantle folds, and possibly in the developingcentral nervous system. In situ hybridizationsfor Twist thus far showed several phases ofexpression inside the embryo, none of whichclearly indicate a role in mesoderm devel-opment. The role of Twist in Patella thereforeremains unclear. We conclude that in mol-luscs, and possibly in all Spiralia, the Twist-snail gene network does not function in me-soderm formation, and that the ancestral roleof the Snail gene family involves epithelial-mesenchymal transitions and nervous sys-tem development.

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46.3 NEDERBRAGT, A.J.*, DICTUS,W.J.A.G., VANLOON, A.E., Utrecht Univer-sity, Netherlands. Conserved gene networksin development: the engrailed and Dpp ho-mologues in molluscan shell development.

During Drosophila development theEngrailed/hedgehog/decapentaplegic genenetwork functions in setting up boundariesbetween different compartments, e.g. be-tween anterior and posterior compartmentsin imaginal discs. Here, Engrailed is ex-pressed in cells on one side of the border.These cells then secrete the Hedgehog geneproduct that reaches the other side of theborder where it induces the expression ofDecapentaplegic (dpp). We are investigat-ing the possible role of this network duringthe development of the gastropod molluskPatella vulgata. We have cloned the Patellavulgata homologues of Engrailed and Dppand analyzed their spatio-temporal expres-sion patterns by in situ hybridization. ThePatella engrailed and Dpp genes are ex-pressed at the border between the shell form-ing epithelium and adjacent ectodermalnon-shell forming cells, with Engrailed be-ing expressed by the shell forming cells. Pre-vious research in our lab has shown that thecells of the shell forming mantle edge cancommunicate via gap junctions with eachother, but not with surrounding tissue. Thisshows that there is a communication com-partment boundary between the Patellaengrailed and Dpp expressing cells. Inter-estingly, insect imaginal disc compartmentsare also communication compartments. Ourresults show that the gene network involv-ing Engrailed and Dpp, has a conservedfunction between Drosophila, Patella andother animal systems, namely setting upboundaries between developmental com-partments. To further confirm this hypothesis,we have recently isolated a Patella hedge-hog homologue and are investigating its rolein setting up this boundary.

S7.6 NELSON, D.R., East Tennessee StateUniversity. Johnson City, Current status ofthe Tardigrada.

The Tardigrada are lobopodousmicrometazoans that occupy a diversity ofniches in marine, freshwater, and terrestrialenvironments throughout the world. Some

have a cosmopolitan distribution, while oth-ers are endemic. About 900 species havebeen described thus far, but many more spe-cies are expected as additional habitats areinvestigated. Most are less than 1 mm in bodylength and are opaque or translucent, ex-hibiting colors such as brown, green, orange,yellow, red, or pink in the cuticle and/or gut.Tardigrades are bilaterally symmetrical, withfour pairs of legs terminating in claws and/orsucking disks. Marine species are more vari-able in body shape and overall appearanceand generally exhibit low populations withhigh species diversity. Reproductive modesinclude sexual reproduction and partheno-genesis, but much remains to be knownabout development. Tardigrades have afluid-filled body cavity (hemocoel), a com-plete digestive tract, and a dorsal lobed brainwith a ventral nerve cord with fused ganglia.Recent molecular analyses and additionalmorphological studies of the nervous sys-tem have confirmed the phylogenetic posi-tion of tardigrades as a sister group of thearthropods. The ability of tardigrades to un-dergo cryptobiosis has long intrigued scien-tists. Although tardigrades are active onlywhen surrounded by a film of water, theycan enter latent states in response to desic-cation (anyhydrobiosis), temperature(cryobiosis), low oxygen (anoxybiosis), andsalinity changes (osmobiosis). Cryptobioticstates also aid in dispersal.

P3.71NEPHEW, B.C.*, ROMERO, L.M., TuftsUniversity. Peripheral arginine vasotocin(AVT) increases corticosterone, but de-creases behavior in European starlings(Sturnus vulgaris).

The neurohormone arginine vaso-tocin (AVT) has been shown to have diverseeffects on numerous avian behaviors includ-ing vocalization, learning, sexual behavior,aggression, and general activity level. It isunclear whether these effects are modulatedby AVT alone, AVT-induced increases in cor-ticosterone concentrations, or by an inter-play of both hormones. To test this relation-ship, AVT was administered peripherally toEuropean Starlings (Sturnus vulgaris) andthe ensuing endocrine and behavioral ef-fects were monitored. Four doses of AVT(0.5, 1.0, 4.0, 8.0ug) were injected subcuta-

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neously and starling behavior wasvideorecorded for 55 minutes. AVT causedsignificant decreases in feeding, drinking,preening, and perch hopping behavior in adose-dependent manner. In a second ex-periment starlings were injected with 0.5, 4.0,and 8.0ug AVT, and 30 minute post-injec-tion blood samples were collected for analy-sis of corticosterone concentrations by ra-dioimmunoassay. Although the 4.0 and8.0ug doses resulted in elevated corticos-terone concentrations, the 0.5ug AVT doseelicited behavioral effects in the absence ofa significant rise in plasma corticosteroneconcentrations. These results suggest thatsystemic AVT may gain entry to the brainand act as a potent neurohormone in star-lings independent of its stimulatory role inadrenocorticotropin release.

44.5 NGUYEN, L*, LECLAIR, E.E., DePaulUniversit., Ontogenetic expression of Plunc,a mouse marker for selected derivatives ofthe pharyngeal epithelium.

In mammalian development the lung andthymus both form from local expansions ofthe embryonic gut tube. The thymus arisesfrom ventral elongations of the third pharyn-geal pouch, while the lung tree starts as aventral outpouching of the foregut. Althoughthe respiratory passages function in breath-ing and the thymus in the maturation of T-cells, both these organs express Plunc, anovel secreted protein, in an unusual pat-tern of epithelial cells. In situ studies showthat Plunc is expressed discontinuously inmouse nasal epithelium starting at embry-onic day 14 and continuing into adulthood.Plunc expression in the lungs begins be-tween day 18 and birth and is present in theentire lining of the trachea and the largebronchial passages. Plunc also appears inthe embryonic mouse thymus on day 14,with segmental staining of the cells surround-ing the larger medullary venules. Althoughno function has been proposed for Plunc,similar sequences have recently beencloned from humans, rats and cows, sug-gesting an evolutionary conserved ontoge-netic expression at least within mammals.In support of this we show that human tra-cheobronchial tissue expresses the humanhomolog Hplunc in a manner similar to that

observed in mice. No sequences homolo-gous to Plunc are present in the genomesof Saccharomyces, C. elegans, or Droso-phila, indicating that this gene may play arole in the immune and/or respiratory matu-ration of “higher” animals. We are now as-sessing this role by colocalizing Plunc withlung surfactant proteins and markers of thethymic epithelium, and by evaluating thebehavior of overexpressed Plunc in primarytracheobronchial cells in vitro. (Supportedby the DePaul University Research Coun-cil)

S13.6NICHOLS, J.S.*, CUTLER, L.M.,HARRISON, J., WHITMER, A.C., ArizonaState University, Tempe. Assessing physicalspace function in a laboratory classroom.

A collaborative effort between ArizonaState University’s Biology Department andthe School of Design created a laboratoryprototype designed to promote a coopera-tive learning and interactive teaching envi-ronment. In this setting, students participatein hands-on group work designed to engagethem in the process of scientific inquiry andfoster their understanding of HumanAnatomy and Physiology. Videotape, per-sonal observation, and student survey dataof space-use and attitudes about sciencewere collected for both pre- and post-reno-vation. This presentation will answer thequestion ”How effectively does this new de-sign promote cooperative learning in a labenvironment?”

P3.5 NICHOLS, P.B.*, GAREY, J.R., Univer-sity of South Florida. Tardigrade evolution-ary relationships.

Tardigrades are a phylum of at least 750species of small (0.1-0.5 mm) animals com-monly known as water bears. They are al-lied with the arthropods and onychophoranswithin Panarthropoda. They live in marine,freshwater aquatic, and limno-terrestrial en-vironments and feed mainly on the cytoplas-mic fluid of plant cells although some arecarnivorous. Many descriptions of tardigradespecies exist, and the families, orders, andclasses are well defined, but it is remark-able that there is currently no hypothesis ofhow the families, subfamilies, and genera ofthis entire phylum are related. The purpose

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of this project is to carry out a combined mor-phological and molecular based phyloge-netic study of tardigrade evolutionary rela-tionships using shared derived characters,18S rRNA, cytochrome oxidase subunit I,and cytochrome b. The phylogeny will pro-vide useful information in understanding howthe various feeding mechanisms, habitatpreferences and cryptobiosis evolvedamong the tardigrades and it is importantbecause tardigrades are central to the un-derstanding of protostome evolution.

9.2 NICHOLSON, G.S.*, JAMISON, M.,KELLEY, K.M., California State University atLong Beach. Insulin-regulated glucose trans-port in muscle of the goby, Gillichthysmirabilis.

In the goby, a total pancreatic endocrineisletectomy (Ix) is followed by hyperglyce-mia and several additional symptoms typi-cal of insulin-dependent diabetes mellitus(IDDM). Insulin treatment of Ix gobies nor-malizes serum glucose levels, with a signifi-cant glucose-lowering effect of the hormoneobservable by as early as 6 hr. In addition,glucose tolerance tests indicate that the Ixgoby is impaired in its ability to clear glu-cose following injection of 250 mg/kg glu-cose, as compared with that in intact gobies,while injection of insulin significantly en-hances glucose clearance rate. The degreeto which these changes in serum glucosemay be associated with alterations in pe-ripheral glucose transport was assessed inpart by measuring the rate of uptake of thenon-metabolizable glucose analog, 3H-2-deoxyglucose, by muscle explants in vitro.Insulin treatment (1 IU/kg) of intact gobiesresults in a 2-fold greater rate of muscle glu-cose uptake as compared with that of con-trols, while in untreated Ix fish it was reducedby half. Furthermore, glucose transport inmuscle from Ix gobies becomes resistant todirect insulin action in vitro, while insulin-replacement therapy of the Ix goby restoresthis response to normal. These data sug-gest the existence of a functional insulin-regulated glucose transport system in thisteleost fish. [Support by NSF grant IBN-9600783 & NIH grant GM50089].

P2.92NICOLAY, C.W.*, SHERWOOD, R.J.,NE Ohio Univs. College of Medicine, Uni-versity Wisconsin, Madison. Eigenshapeand biomechanical analysis of thephyllostomid mandibular symphysis.

Bats of the family Phyllostomidae arecharacterized by considerable dietary diver-sity, which may be reflected in the morphol-ogy of the mandibular symphysis. Symphy-seal outline shapes and biomechanical prop-erties of the symphysis were compared us-ing bone densitometer (CT) scans (midlinesagittal sections) of dry skulls. The diets ofthe 9 species (71 individuals) sampled rangefrom fig specialists to dedicated nectarivores.Eigenshape analysis was performed toquantify symphyseal outline shape. CT sec-tions were digitized and converted PHI* co-ordinates, which were then subjected to asingular value decomposition using the co-variance matrix. Biomechanical propertiescalculated from bitmap images included cor-tical bone area, area moments of inertia, andangular orientation of the symphysis. Bothtechniques yield broadly similar (but not iden-tical) results, effectively separatingnectarivorous from frugivorous species, withomnivorous species falling intermediately.The second eigenshape factor (E2) is posi-tively correlated with all biomechanical pa-rameters (r = 0.52 - 0.59) and symphysealorientation (r = 0.75), but other eigenshapefactors (E1 and E3) are not well correlatedwith any mechanical variables or linear mea-surements. Both E2 and mechanical pa-rameters are strongly correlated with palatelength/breadth ratios and measures of man-dible size (r = 0.63 - 0.87). When mappedonto published phylogenies, outline shapefunctions show a relatively strong phyloge-netic signal, while biomechanical propertiesappear to be associated with finer patternsof dietary and allometric variation.

S7.12 NIELSEN, C., UniversityCopenhagen, Zoological Museum. Thephylogenetic position of Entoprocta,Ectoprocta, Phoronida and Brachiopoda.

Ectoprocts, phoronids and brachiopodsare often dealt with under the headingTentaculata or Lophophorata, sometimeswith entoprocts as a more or less closely

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related group. The Lophophorata is pur-ported to be held together by the presenceof a “lophophore”, a mesosomal tentaclecrown with an upstream-collecting ciliaryband on monociliate cells. However, the ten-tacle crown of pterobranchs is an identicalstructure, although its ontogeny is not welldocumented. On the contrary, the ectoprocttentacle crown carries a ciliary sieving sys-tem with multiciliate cells and the body doesnot show archimery, neither during ontog-eny nor during budding, so the tentaclescannot be characterized as mesosomal. Theentoprocts have tentacles without coelomiccanals and with a downstream-collectingciliary system like that of trochophore larvaeand adult rotifers and serpulid and sabellidannelids. Planktotrophic phoronid and bra-chiopod larvae develop tentacles at an earlystage, but their ciliary system resembles thatof echinoderm and enteropneust larvae.Ectoproct larvae are generally non-feeding,but the planktotrophic cyphonautes larvaeof certain gymnolaemates have a ciliary bandresembling that if the adults. The entoproctshave typical trochophore larvae and manyare feeding with the downstream-collectingciliary bands. Phoronids and brachiopodsare thus morphologically on the deuteros-tome line, probably as the sister group of the“Neorenalia” or Deuterostomia s.str. The en-toprocts are clearly spiralians, although theirmore precise position has not been deter-mined. The position of the ectoprocts is un-certain, but nothing in their morphology in-dicate deuterostome affinities; certain detailsin their metamorphosis may point to a rela-tionship with the entoprocts.

48.6 NIEWIAROWSKI, P.H.*, ANGILLETTA,Jr., M.J., LEACHE, A.D., PORTER, W.P., Uni-versity of Akron, Akron OH, Indiana StateUniversity, Terre Haute IN, Louisiana StateUniversity, Baton Rouge LA, University ofWisconsin, Madison WI. Phylogenetically-based comparative analysis of life historyvariation among populations of Sceloporusundulatus.

The eastern fence lizard, Sceloporusundulatus, is one of the most widely distrib-uted lizards in North America. Across itsrange, populations display two- to three-fold

variation in many life history traits, includingage at maturity, adult body size, clutch size,and longevity. Although this variation hasbeen the subject of extensive empirical andtheoretical study, comparative analyses oflife history variation have been limited bythe lack of a population level phylogeny. Weused a phylogeny inferred from sequencesof mitochondrial DNA to construct indepen-dent contrasts for comparative analyses of13 widely-distributed populations. Our analy-ses explore patterns of covariation amonglife history traits predicted by life history theory(e.g., egg size vs.clutch size, reproductiveoutput vs. survival), as well as covariationamong life history traits and environmentalparameters (e.g., precipitation, temperature,activity season length estimates derived froma biophysical model). Our study representsthe first time that life history variation in thisspecies has been interpreted within a rigor-ous phylogenetic framework. Intraspecific,phylogenetically-based comparative stud-ies, like ours, provide insights for develop-ing testable hypotheses about life historyevolution and adaptation.

P3.28NINOMIYA,H.*, ELINSON, R.P., Uni-versity of Toronto, Canada, Duquesne Uni-versity, Pittsburgh. The geometry of meso-derm formation in the direct developerEleutherodactylus coqui, a frog with bigeggs.

E. coqui is a direct developing frog, whichhatches as a froglet without going through atadpole stage. It develops from a big egg(diameter 3.5mm), much of which forms largeyolky cells, which are assumed to have pri-marily a nutritive role. The large fraction ofthe egg devoted to yolk may affect the geo-metric disposition of germ layer formation inthis embryo. To address this question, weinvestigated mesoderm formation in E. coquiand compared it to that of Xenopus laevis(egg diameter 1.3mm). First, we examinedthe position of prospective mesoderm alongthe animal-vegetal axis of the egg. Animaland vegetal regions are initially divided bythe fourth cleavage furrow, close to the ani-mal pole, unlike in X. laevis, where the ani-mal cells are formed by the third cleavage ina supra-equatorial position. We followed cell

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lineage of 16-cell E. coqui embryos by in-jecting them with the lineage tracerRhodamine dextran amine. Although ani-mal cells are small, they form most of theblastocoel roof and make extensive contri-butions to differentiated mesodermal tissues.Second, we performed recombinant analy-sis to examine which regions have meso-derm inducing activity. We combined partsof E. coqui blastula or early gastrula with X.laevis animal cap and examined mesodermdifferentiation of X. laevis cells. Mesoderminducing activity was restricted to the mar-ginal or sub- marginal regions in E. coqui.Neither the vegetal pole nor the inner veg-etal core, including the blastocoel floor, hadactivity, although these same regions fromX. laevis blastulae induced mesoderm. Ourresults suggest that mesoderm formation isshifted to more animal and superficial re-gions in E. coqui compared to X. laevis.

20.3 NISHIGUCHI, M.K.*, New MexicoState University. Reverse physiological pat-terns between sepiolid squids and their lu-minous bacterial symbionts: host specificityexamined from down under.

Mutualistic associations between bacte-ria and their eukaryotic hosts have a varietyof mechanisms that determine patterns ofhost specificity among symbionts during in-fection and colonization. Although mostsymbiotic bacteria are only capable of in-fecting their particular host partner, closelyrelated strains with similar host species havebeen shown to colonize and persist in otherhost species. Sepiolid squids (Cephalopoda:Family Sepiolidae) and their bioluminescentbacteria (Genus Vibrio) are one examplewhere symbiotic bacterial strains are capableof infecting similar host species. These dif-ferent symbiotic strains have the same in-fection and colonization behavior as do na-tive strains, but when placed in direct com-petition with one another, the native strain isalways dominant. This study examined howsymbiotically competent Vibrio fischeristrains isolated from Australian Euprymnatasmanica display dominance for nativesquid hosts over other equally competent V.fischeri strains isolated from other sepiolidsquids. Infection by bacterial symbionts from

the monocentrid fish Cleidopus gloriamarisand the loliginid squid Photololigo noctilucaproduced a lesser degree of infection, de-spite their presence in the same geographi-cal location. Since previous studies haveshown that a similar phenomenon occurs inthe sister species E. scolopes (Hawaii), thiscomparision of both host species exempli-fies the importance of host-symbiont recog-nition in habitats where symbiont composi-tion is dictated by a specific host and not theenvironment.

S3.10NISHIKAWA, K.C., Northern ArizonaUniversity Feeding motor patterns: insightsfrom biomechanical modeling.

Biomechanical modeling and empiricalstudies in my laboratory over the past tenyears have produced a number of insightsinto activation patterns of tongue and jawmuscles during feeding in frogs. One insightfrom empirical work, confirmed by biome-chanical modeling, is that activation patternsof antagonistic muscles change with bodysize. For example, in toads, the onset time ofthe tongue retractor muscles relative to thetongue protractors changes systematicallywith body size. This occurs because the con-traction and relaxation times of individualmuscles are independent of body size,whereas the duration of activation is directlyproportional to linear dimensions. As ani-mals grow, the relative onset times ofmuscles change so that peak force is devel-oped at the same time during the feedingcycle. The implication of such considerationsis that neither are muscle activation patternsconstant during the lifetime of individualswithin a species, nor can they be character-istic of a species as a whole. A second in-sight from biomechanical modeling, whichis consistent with a large body of empiricalwork, is that the genioglossus muscles offrogs, long considered as tongue protrac-tors, are actually an order of magnitude toosmall to affect the tongue trajectory duringprotraction. Tongue protraction is dynami-cally stable, and is powered mostly by an-gular momentum transferred from the open-ing jaws to the tongue. Connective tissuesin the tongue are designed to resist or per-mit tongue elongation. We hypothesize that

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the genioglossus muscles themselves,rather than powering tongue protraction, mayperform some other essential role, such asbreaking surface tension between thetongue and the lower jaw. Biomechanicalmodels, coupled with empirical studies, of-ten suggest functional hypotheses that arenot intuitively obvious.

61.5 NORCLIFFE, H. R.*, WATTS, P., CAR-RIER, D. R., Applied Fluids Engineering, Inc.,Applied Fluids Engineering, Inc., Universityof Utah, Salt Lake City. Comparative study ofhuman locomotion in microgravity.

Because human locomotion evolved withthe burden of gravity, locomotion is difficultin space. The absence of significant gravita-tional force could make human flight com-monplace in a space station. To addressthis possibility, we analyzed mechanisms ofanimal locomotion applied to an astronautin a space station. Our analyses indicatethat humans could fly, but with relatively poorperformance. Acceleration and turning agil-ity would be much less than we are accus-tomed to on Earth, but limits on initial accel-eration could be overcome, in most cases,by pushing-off from solid surfaces. With aninitial take-off jump, relatively small wingsmounted on the arms would give an astro-naut a capacity to turn and change body ori-entation in a controlled manner. Becausewe are not structured to flap our arms asbirds and bats do, we could produce greateraccelerations using various methods of drag-based propulsion. Unfortunately, turningagility with drag-based propulsion would belimited by the intermittent generation of turn-ing forces that is necessitated by the recov-ery stroke. The most versatile system oftransport would likely be a space bike thatwould allow an astronaut to convert themuscular power of the human leg into a di-rected momentum flux of air, albeit with muchless effort than needed on earth. Our resultsyield insight into the effect of gravity on theevolution of viable forms of animal locomo-tion. Our analyses also reinforce the efficientuse of rotation by modern engineering.

P1.49NORDEEN, J.M.*, SHEFFIELD, E.M.,KINSEY, S.T., University of North Carolina atWilmington. Size- and salinity-dependent en-zyme activities in gills of the blue crab.

In the lower Cape Fear River estuary,populations of juvenile (< 12 mm carapacewidth) blue crabs, Callinectes sapidus, arefound at low salinity (<5 ppt). This distribu-tion pattern may have ecological benefits,such as predator avoidance, but it also leadsto increased metabolic costs associated withATP-dependent osmoregulation. The osmo-regulatory costs should be particularly highfor the smallest animals, which have thehighest surface area-to-volume ratio. Wehypothesized that the increased metaboliccost of size-dependent osmoregulation atlow salinities would be reflected in the activ-ity of enzymes of energy metabolism in thegills. We measured activities of hexokinase,lactate dehydrogenase, citrate synthase,glutamate dehydrogenase andhydroxyacyl-CoA-dehydrogenase as a func-tion of animal size and acclimation salinity.Measurements were made on posterior gills(6 and 7), which are principally involved withosmoregulation, and in anterior gills (3 and4), which are principally respiratory. Salinitytreatments were 7 days acclimation to 5, 17or 34 ppt and four size classes were selectedfrom the smallest juveniles to adults. Thedata were interpreted both in terms of salin-ity treatment and animal scaling laws.

P1.66B NOREN, D.P.*, WILLIAMS, T.M.,University of California, Santa Cruz. Effectsof environmental regime and body condi-tion on resting metabolic rates in northernelephant seal pups: does RMR measuredin ambient air represent true RMR?

Northern elephant seal pups (Miroungaangustirostris) are weaned at body massesthat are 30 - 50% lipid. Due to the widerange of body compositions at weaning,northern elephant seals provide a goodmodel to examine how body condition influ-ences resting metabolic rates (RMR) andthermal conductance under different tem-perature regimes. Percent body lipid (viatritium dilution), RMR (via open flowrespirometry), and core body temperature(Tb) were determined in 17 fasting pups rest-

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ing in ambient air (20.9 ± 3.3 ∞C), cold water(3.8 ± 1.7 ∞C), and warm water (14.1 ± 1.8∞C). We found that percent lipid (range:34.4% - 43.8%) tended to increase with bodymass (range: 62.0 kg - 108.0 kg) but was notcorrelated with RMR. RMR was correlatedwith total body mass and lean body mass.RMR increased with body mass in air (R =0.71, P = 0.002) and cold water (R = 0.66, P= 0.004), but not significantly in warm water(R = 0.45, P = 0.068). RMR (range: 293.6mlO2 min-1 - 521.7 mlO2 min-1) differed (P =0.050) between the three regimes, with thehighest mean RMR in warm water and thelowest RMR in cold water. Furthermore, RMRtended to increase with environmental tem-peratures. Thermal conductance, calculatedfrom RMR and Tb, increased with environ-mental temperature, more steeply in ambi-ent air than in water. These results indicatethat body condition and environmental re-gime have synergistic effects on RMR andthermal conductance for resting northernelephant seals. A consequence of largebody size and high body lipid content is anelevation in RMR and thermal conductance,particularly when resting in ambient air, withthe result that minimum RMR occurs whenthese mammals are in cold water.

P1.66C NOREN, S.R.*, LACAVE, G.,WELLS, R.S., WILLIAMS, T.M., University ofCalifornia, Santa Cruz, Boudewin Park, Chi-cago Zoological Society, University of Cali-fornia, Santa Cruz. Development of bloodoxygen stores in bottlenose dolphins(Tursiops truncatus).

Increased blood oxygen reserves facili-tate diving in marine mammals. Previousstudies show that pinnipeds require a de-velopmental period for blood oxygen storesto reach adult capacities. We investigated ifa developmental period for the blood alsooccurs in cetaceans which unlike pinnipeds,are exposed to diving immediately after birth.Blood samples were collected from bottle-nose dolphins aged 0-12 years from wildand captive populations to determine redblood cell number cell number (RBC), he-moglobin content (Hb), hematocrit (Hct),mean corpuscular volume (MCV), mean cellhemoglobin (MCH), and mean corpuscular

hemoglobin concentration (MCHC). Wefound that during postnatal development,RBC, Hb, and Hct decrease from 0-1.5months and then increase significantly from1.5-6 months, reaching adult levels by 3years. MCV and MCH significantly increasefrom birth until 2 months of age at which timethey approximate adult values. MCHC sig-nificantly decreases from 0-3.2 months, thenincreases and approximates adult values by6 months. Because weaning occurs at 1.5years for bottlenose dolphins, the develop-ment of the blood oxygen store is not com-plete with the initiation of independent for-aging. The lower oxygen storage capacityof immature dolphins undoubtedly limits divecapabilities as indicated by aerobic dive lim-its (ADL) calculated from our blood data.ADLs of 0-3 year olds (1.9-4.8 min) are lowerthan the ADLs of 4-8 and 9-12 year olds (5.1and 5.4 min, respectively). Increases in ADLfrom 0 to 3 years are attributed to increasesin body mass and mass specific oxygenstores while body mass alone explains theincreases in ADL for dolphins 3 to 9 years.

P1.4 NORENBURG, J.L.*, ROE, P.,Smithsonian Institution, Washington, DC,Calif. State University-Stanislaus, Turlock.New sticky things in holopelagic nemerte-ans.

Biology and diversity of delicate, gelati-nous, holopelagic deep-sea organisms con-tinue to be sources of major surprises, de-spite more than a century of studies. Nem-erteans are among the least studied groupsof these organisms. Recent collaborativedeep-sea mid-water collections made with J.Childress (UCSB) and Monterey BayAquarium demonstrated that taxonomic di-versity of holopelagic nemerteans was vastlyunder-appreciated and that previously stud-ied species were poorly known. One surpriseis a pair of epidermal, specialized glandularregions found near the posterior of the body,more or less along the left and right lateralmargins, occuring in 13 of our recently col-lected morpho-species. The taxonomic distri-bution of the glandular structures is sugges-tive of a strong phylogenetic correlation, pro-viding some welcome relief in this character-impoverished group of worms. In fact, the

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structures appear to constitute asynapomorphy for Pelagonemertidae andBalaenanemertidae.These glandular struc-tures generally appear as an elongate patchof thickened epidermis comprised of twomostly segregated types of glandular cells,with staining properties suggestive of acidmucins and more proteinaceous mucoids re-spectively. A key attribute of these structuresis strong bonding with underlying connectivetissue, unlike the rest of the epidermis, whichis readily lost in the collecting process. Ho-mology of these structures with a ventral, morecomplex glandular specialization known pre-viously from Plotonemertes remains to betested. In the course of our study we foundadditional regional glandular specializationof epidermis in three other species of pelagicnemerteans; these seem to be non-homolo-gous. Neither structure nor location offer self-evident suggestions for function of these spe-cializations.

S10.18 NORRIS, R.D., Woods HoleOceanographic Institution. Evolution ofphotosymbiosis in planktic foraminifera.

Photosymbiotic relationships have beenestablished at least seven times betweenlarge clades of planktic foraminifera (unicel-lular marine protists) and dinoflagellate au-totrophs in the past 100 million years. Algalsymbionts impart a distinct carbon isotopechemistry on the host foraminifera that canbe detected even in extinct species. Carbonisotope data show that planktic foraminiferphotosymbiosis first evolved in the late Cre-taceous (~75-80 Ma). Photosymbioticclades were wiped out during the Creta-ceous/Paleogene mass extinction (65 Ma),re-established in a different clade in themiddle Paleocene (~61 Ma), eliminatedagain about 38 Ma and re-established for athird time in four separate subclades ofplanktic foraminifera starting about 18 Ma.The first two diversifications of thephotosymbiotic ecology coincide with thosein the host foraminifera and suggest that theestablishment of the symbiotic relationshipallowed the host group to radiate into nutri-ent-stressed habitats. However, the most re-cent re-acquisition of photosymbiosis oc-curred in a number of different subclades of

a group of foraminifera that had begun itsradiation 6-8 million years earlier. Hence,although there is some evidence for coevo-lution between planktic foraminifera andtheir algal symbionts, this is not always thecase. Photosymbiosis may allow diversifi-cation into environments where competitionis weak and lead to the spread ofphotosymbiotic groups. However, consid-erable diversity of photosymbiotic taxa canalso develop through colonization of an al-ready diverse clade by the algal partner.Clearly the context of radiation is importantin determining the macroevolutionary effectsof the establishment of symbioses.

P2.14NOWICKI, J.L.*, TAKIMOTO, R.,FOLEY, A.B., BURKE, A. C., University ofNorth Carolina-Chapel Hill, Wesleyan Uni-versity, Wesleyan University, Wesleyan Uni-versity. Global patterning information in thelateral plate mesoderm.

The somitic mesoderm produces the axialskeleton and the striated muscle of both bodyand limbs of vertebrates. The limb skeletonand connective tissue develops from cellsof the lateral plate mesoderm. To functionproperly, the elements of the appendicularand axial systems must be coordinated dur-ing development; for instance the limbs needto be in register with regional changes in thevertebral column. This patterning is realizedduring development as cells from thesomites migrate into the lateral plate anddifferentiate into specific muscles. There is aboundary that separates the dorsal compart-ment (somitic cells only) from the ventralcompartment (somitic and LP cells) that wecall the somitic frontier. Previous experimentsin avian embryos have shown that somiticmesoderm forming structures in the dorsalcompartment of the body (axial skeleton,paravertebral muscles, dorsal dermis) is in-trinsically patterned, i.e. it maintains its axial,morphological identity despite transplanta-tion to a new anterior-posterior (AP) axialaddress. Furthermore, Hox gene expressionis also maintained in transplanted tissue,strengthening the correlation between Hoxgene activity and AP patterning of axial tis-sues. The somitic cells that cross the somiticfrontier and form limb and abdominal

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muscles, however, appear to come underthe influence of the lateral plate. It is uncer-tain whether the lateral plate mesoderm hasan intrinsic axial identity with regard to bothmorphology and Hox expression. Using thequail-chick chimera system we are perform-ing heterotopic transplants of lateral platemesoderm to determine the nature of pat-terning information in the lateral plate, andthe role of Hox gene expression in this tis-sue.

20.5 O’BRIEN, J.J.*, BOETTCHER, A.A.,BOONE, E., SHERMAN, T.D., University ofSouth Alabama. Chemical cues and vulner-able hosts: an investigation into factors af-fecting settlement of Loxothylacus texanus,a rhizocephalan barnacle parasitizingportunid crabs in the Gulf of Mexico.

The parasitic castrator, Loxothylacustexanus, stunts the growth and inhibits re-production of economically importantportunid crabs in the Gulf of Mexico whereprevalence has been reported to be higherthan 50% in some localities. Data from ex-periments utilizing lectins and specificsugars as inhibitors indicate that mannosein/on postmolt exoskeleton plays an im-portant role in the recognition signal usedby the barnacle to identify vulnerable hosts.Enhanced settlement occurred onpostmolt exoskeleton that had beentreated with chloroform to remove lipidssuggesting that lipids may serve to maskthe recognition signal. Removal of pro-teins from substrates by the action of Pro-teinase K, on the other hand, did not affectsettlement. Settlement did occur underlaboratory conditions on exoskeleton fromspecies of decapods not known to be in-fected by the parasite. The latter data sug-gest caution before using rhizocephalansas biological control agents as has beenproposed by others.

P2.49O’BRYANT, E.L.*, WADE, J., MichiganSt. University Sexual dimorphisms in neuro-muscular junction morphology in the greenanole lizard.

The green anole lizard exhibits seasonalcourtship behavior that is sexually dimor-phic. It consists of the extension of a brightred throat fan, called a dewlap, along with

head-bobs and a push-up display. Whilemales extend the dewlap in aggressive en-counters as well as in courtship, females usetheir diminutive dewlap much less fre-quently, and in agonistic encounters only. Inparallel, a number of components of theneuromuscular system controlling dewlapextension are sexually dimorphic during thebreeding season. For example, length ofthe second ceratobranchial cartilage (whichbows out to extend the dewlap), dewlap mo-toneuron soma size, as well as dewlapmuscle fiber size and number are all greaterin males than in females. In the presentstudy, intact males and females were sacri-ficed during the breeding season and thedewlap muscle and surrounding cartilagepieces (ceratohyal and first ceratobranchial)were extracted and post-fixed for 1 hr. Thelength of the muscle was measured in twodimensions: (1) along fibers between the twocartilage pieces, and (2) along the muscleparallel to them. The muscle was thenstained for acetylcholinesterase to visualizeneuromuscular junctions (NMJ) on the fi-bers. The cross-sectional area and densityof NMJ were then measured for each ani-mal. NMJ were on average larger in malesthan in females (p=.022), but their densityalong each fiber was equivalent betweenthe sexes (p=.094). In addition, the length ofthe overall muscle (p<.0001), but not indi-vidual muscle fiber length (p=.372) waslarger in males than in females. These re-sults are consistent with the idea that en-hanced NMJ size either facilitates or is aconsequence of increased use of a largerdewlap in breeding males compared to fe-males. Supported by NSF IBN-9733074.

S1.2 O’CONNELL-RODWELL, C.E.*,ARNASON, B., HART, L.A., Stanford Univer-sity, Tezar, Inc., Austin, TX, University of Cali-fornia, Davis. Exploring the possibility of low-frequency seismic communication in el-ephants and other large mammals.

As an elephant vocalizes with low fre-quency rumbles, a signal replica is propa-gated in the ground. Using seismic model-ing, we estimated that the elephant rumblesthat we recorded could potentially travel upto 16.7 km in the ground and foot stompsfrom a mock charge could possibly travel up

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to 32 kilometers. To determine if elephantscan detect these seismic signals, we con-ducted seismic playback experiments withAfrican and Asian elephants. Previously re-corded seismic components of particularelephant vocalizations were played backthrough two specially adapted 50 W seis-mic transmitters at 10 m distances from theelephant. A TEAC digital recorder providedthe signal source for the transmitters. Play-back signals and elephant responses wererecorded close to the elephant on a TASCAM2-channel digital recorder through a 20 HzMandrel geophone and Neumann low fre-quency microphone. Real time monitoringon a laptop using SpectraPLUS software en-sured signal integrity, without coupling intothe air. To assess detection of seismic sig-nals, elephant behavior was monitoredthrough video and visual observations. Weare also investigating organs of interest onthe elephant’s head and feet as candidatesfor special seismic and auditory sensitivity.If elephants detect seismic components oftheir vocalizations, communication may bepossible at greater distances than previouslythought. The results of this study may havesignificant implications for elephant long dis-tance communication and a better under-standing of elephant audition. Possible seis-mic communication in other large mammalssuch as lions and bison is also discussed.

12.2 O’CONNOR, M.P.*, ZIMMERMAN,L.C., SPOTILA, J.R., Drexel University, Uni-versity of Nevada, Reno, Drexel University.Effects of behavior, physiology, and habitaton thermoregulation in desert tortoises.

Desert tortoises are herbivorous ecto-thermic denizens of the Mojave andSonoran deserts whose thermal ecologyconstrains activity and resource acquisitionon both seasonal and daily time scales. Weused behavioral observations of individualtortoises with temperature sensitive teleme-ters, operative temperature models, and re-cently developed analytic techniques to es-timate both operative and available bodytemperatures to study the thermal ecologyof free-ranging tortoises near Las Vegas, NV.We particularly addressed the roles of habi-tat and microhabitat choices, thermal inertia

(due to relatively large body size), and thephysiological control of heating and coolingin controlling body temperatures. Analysesof available operative temperatures sug-gested that thermal constraints on activityvaried both seasonally and day-to-day. Theyalso reveal a role for burrow use as a ther-mal refugium and a possible role for selec-tion among surface microhabitats in control-ling body temperatures. Microsites undershrubs warmed significantly slower thanother microhabitats. Contrary to a priori pre-dictions, sites near, but not under, shrubswere often among the hottest available sites.Much of the microsite-based diversity in op-erative temperature occurred during the hot-test parts of the day when tortoises could notbe active, but some diversity was availableat times when tortoises were active. Bothobservations of telemetered tortoises andbody temperatures predicted from operativetemperatures using a model of heating andcooling in tortoises support an important rolefor the tortoise’s thermal inertia in bufferingbody temperatures from rapidly rising andfalling operative temperatures. The role andimportance of physiological control of warm-ing and cooling is much less clear.

P1.65O’CONNOR, T.P.*, GIBBS, C.L.,KUROIWA, K., City College of New York,CUNY. Effect of cold-acclimation on housefinch metabolism and organ sizes.

Two of the most intensively studied pro-cesses in the field of ecological physiologyare the limits to metabolic performance andthe energetics of temperature acclimation.A major emphasis currently is the examina-tion of relationships among basal metabolicrate (BMR), maximum metabolic rate (MMR),and the sizes of vital organs and tissuessuch as kidneys, liver, heart, and skeletalmuscle. We examined these relationshipsin house finches (Carpodacus mexicanus)that were maintained in the laboratory at twodifferent acclimation temperatures. Birds inthe cold-acclimation (CA) group were main-tained at 5ƒC, and those in the warm-accli-mation (WA) control group at 25ƒC, for sixweeks following capture in New York in June.All metabolic rate values were measured asoxygen consumption in an open-circuit

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respirometry system. MMR was determinedby two methods for each animal: exercisemaximum in a running wheel chamber andthermogenic maximum during exposure tocold temperatures in a helium-oxygen(heliox) atmosphere. The body mass of CAbirds (20.1±0.5 g) was significantly greater(p<0.001) than that of WA birds (18.4±0.3 g).Even when adjusted for differences in bodymass, the BMR of CA birds was 15% greaterthan that of WA individuals (p<0.01). How-ever, there was no effect of acclimation tem-perature on either exercise or cold-inducedMMR. Exercise-induced MMR values were17.5% greater than those obtained using theheliox protocol (p<0.01). The relationshipsamong organ sizes and metabolic measure-ments will be discussed.

P2.87O’REILLY, J.C.*, KLEY, N.J., RICH-MOND, A.M., BRAINERD, E.L., University ofMassachusetts Amherst. Prey capture kine-matics in Chelus fimbriatus (Testudines:Pleurodira).

Many aquatic turtles can successfullycapture elusive aquatic prey but few, if any,approach the abilities of the South Ameri-can matamata (Chelus fimbriatus). The goalof this project is to use high-speedvideography, fluoroscopy and anatomicaldissection to gain a better understanding ofthe exceptional suction feeding abilities ofChelus. Unlike most turtles, the skull ofChelus is dorsoventrally flattened and thedistal half of the mandible is reduced to athin rod of bone. Unlike any other turtle,Chelus possess no lateral gape when themouth is open; a large flap of skin unfolds atthe angle of the gape and restricts the circu-lar mouth opening to a single plane. The hy-oid skeleton is large relative to similar sizedindividuals of other species and very robust,functioning as a four-bar linkage system toexpand the pharynx both ventrally and lat-erally in response to posteriorly directedforces generated by the M. rectus cervicus.In addition to its many morphological pecu-liarities, the strike of Chelus is much fasterthan that of any other turtle for which dataare currently available (peak gape in 10-15ms for individuals with 13 cm carapacelength). The combination of this unique suite

of characters adds up to exceptional suctionfeeding abilities at the apparent expense ofbiting performance. The combination of asuch an extremely flattened skull with an at-tenuated mandible, results in Chelus beingeffectively incapable of biting. This researchis supported by a UMass/OEB DarwinPostdoctoral Fellowship to JCO and NSFgrant IBN-9875245 to ELB.

50.4 OAKLEY, T.H., Duke University. Mul-tiple lines of evidence support the indepen-dent origin of an arthropod compound eye.

One of the most debated issues in ar-thropod evolution is whether compound eyesevolved once or multiple times. One reasonthis issue has remained unresolved is thatmost previous researchers have relied onsingle lines of evidence. Here I present fourseparate lines of evidence that the com-pound eyes of ostracod crustaceans are in-dependently derived. The first evidence isphylogeny. Myodocopids - the only ostra-cods with compound eyes - are phyloge-netically nested within several groups thatlack compound eyes. Sequence analysesof 28S and 18S rDNA unequivocally sup-port this result. Second, I have documenteda recent duplication of visual pigment genes(opsins) coupled with a change to com-pound eye-specific gene expression. Thetiming of these events are coincident withthe origin of myodocopids and therefore theputative origin of ostracod compound eyes.The recent origin of a compound eye-spe-cific opsin is especially compelling becauseI cannot detect any other compound eye-opsins in ostracods with older origins. Theancestral absence of compound eye opsinssuggests an ancestral absence of com-pound eyes themselves because all meta-zoan eyes express opsin. Third, one wouldexpect a unique structure in independentlyderived organs. The ultrastructure of the fac-ets of ostracod compound eyes deviatesfrom the common arthropod structure of eightretinular cells and four crystalline cone cells.Ostracods have six and two, respectively.Finally, the oldest known fossil ostracod witha compound eye is also the oldestmyodocopid. No fossil compound eyes areknown from ostracods older than

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myodocopids. Taken together, these dataprovide the strongest case yet for the mul-tiple origin of arthropod compound eyes.

9.5 ODELL, J.P.*, CHAPPELL, M.A., Uni-versity of California, Riverside. Variation inaerobic capacity within and among “com-mon-garden” populations of trinidadian gup-pies (Poecilia reticulata) from different pre-dation regimes.

We measured maximal oxygen uptakerates (VO2max) in laboratory-reared F2 andF3 offspring of Trinidadian guppies from fourdifferent streams. These streams representhabitats that differ in predation intensity andflow characteristics, and contain guppies thathave evolved significantly different life his-tories. Guppies were exercised in a smallclosed chamber at increasing speeds untilthey began sprinting. Control experimentsdemonstrated that the exercise protocolcaused elevated whole-animal lactate lev-els, and did not cause hypoxic conditions inthe chamber. We found that VO2max in gup-pies was a repeatable trait when measuredover one-week and three month intervals,although the correlation between measure-ments decreased over time. Within popula-tion variation in VO2max ranged between 10and 13% when the effect of body mass wasremoved by regression. Within streams,aerobic performance did not differ betweenthe sexes. Male performance was not sig-nificantly different among locales; however,female performance was highly variableamong streams. In addition, our data sug-gest a significant effect of stream predationlevel on female performance. Elucidatingthe evolutionary forces for the observed dif-ferences in female performance requiresfurther study of more stream pairs. In light ofrecent studies showing rapid evolution oflife-history traits in wild guppies, it is of notethat this selection regime does not appearto affect male aerobic performance.

20.4 OKAMURA, B.*, ANDERSON, C.L.,CANNING, E.U., University of Reading,Reading, U.K., Imperial College of Science,Technology and Medici, Imperial College ofScience, Technology and Medici. An ancientclade of myxozoans parasitic in freshwaterbryozoans.

The Myxozoa, an enigmatic group of en-doparasites, is marked by a long history ofphylogenetic and taxonomic uncertainty.Originally classified as protists, it is now clearthat myxozoans are proper metazoans, al-though controversy remains as to whetherthey are highly degenerate triploblasts ordiploblasts. In addition, taxonomic revisionwas required when it was discovered thatcertain myxozoan parasites of worms go onto infect fish, thus uniting within one life cycle,forms that were previously assigned to sepa-rate classes. This discovery led to the de-mise of the Class Actinosporea leaving asingle class, the Myxosporea, in the phylum.Recently we have described two myxozoanspecies that occur as parasitic sacs withinthe body cavity of freshwater bryozoans(Class Phylactolaemata). Comparisons ofmorphologies and life cycles have revealedmajor differences between these bryozoanparasites and the myxozoan parasites of fishand worms. Phylogenetic analysis of 18SrDNA sequences identifies two clades withinthe Myxozoa that diverged early in the evo-lution of the group. Our studies suggest thatbryozoans may have been ancestral hostsof myxozoans and provide the basis for iden-tifying a new class of myxozoans, theMalacosporea. Finally, our discovery of thebryozoan parasite, Tetracapsula bryo-salmonae, has identified the source of thecausative agent of Proliferative Kidney Dis-ease, a devastating disease of salmonid fish-eries resulting from accidental infection by apreviously unknown myxozoan.

36.5 OLIVER,S.J.*, LOBEL, P.S., BostonUniversity Marine Program. Female matechoice based on male acoustic displays indomino damselfish, Dascyllus albisella.

Male Dascyllus albisella produce anacoustic and visual courtship display. Atagged population of fish (29 males and 31females)at Johnston Atoll (Central PacificOcean) were observed for three months toassess the correlates of male mating suc-cess. Phenotypic, behavioral, and territo-rial characteristics of males were measuredand compared to male mating success (mea-sured as ratio of clutches receiver per 6-daymating cycle) No component of male phe-notypic quality or territory quality was sig-

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nificantly correlated to mating success. Onlythe acoustic call repetition rate was signifi-cantly correlated to male mating success.Previous work on damselfish suggests thatcall repetition rate is indicative of energeticreserves, which was reflected in higher qual-ity paternal care of eggs. This suggestsmales are advertising their available energyas an indication of the quality of paternalcare they are likely to provide to eggs. Weexamine this data with reference to prevail-ing theory, particularly the good genes ver-sus good parent process hypotheses ofsexual selection.

P2.12OLSON, W.M.*, HALL, B.K., DalhousieUniversity, Halifax, N.S. Heart morphogen-esis and neural crest cell migration in cardiabifida chick embryos.

During normal development, cardiacneural crest cells migrate from their positionover the neural tube, through the pharyn-geal region and into the heart, where theycontribute to the septation of the heart andoutflow tract, as well as to the cardiac valvesand great vessels. The primitive heart tubeof higher vertebrates is the result of migra-tion and fusion of bilateral cardiac primordiaalong the ventral midline of the embryo.Cardia bifida, or “split hearts” can be inducedby cutting the anterior intestinal portal (AIP)early in development, thus preventing fusionof the heart primordia. Bifid embryos pos-ses two lateral hearts instead of one me-dian, and pharyngeal development is dis-rupted. In vitro methods, in which embryoswere cultured ventral side up on thin albu-min, produced cardia bifida (100%), but didnot allow development past ST 11. Cultur-ing the embryos on semisolid medium (1:1agar:albumin) permitted development to ST16. In ovo techniques, in which the AIP wascut either from the lateral dorsal side of theembryo or by cutting straight through thedorsal midline, proved less successful at pro-ducing bifida (up to 50%), but prolongedsurvival until ST 24. No completely bifid em-bryos survived past ST 17. HNK-1, a neuralcrest marker, was used to analyze whethermigration of the cardiac crest is altered incardia bifida embryos. Initial results sug-gest that the distribution of HNK-1 positive

cells is similar in experimental, sham, andundisturbed embryos, with the following ex-ceptions. Starting at stage 16, experimentalembryos show transverse streams of posi-tive cells crossing the dorsal hindbrain; inST 16-20, HNK-1 is limited to the proximalregions of the pharyngeal arches and doesnot extend as far distally as in the non-ex-perimental groups.

S9.8 ORCHINIK, M.*, BREUNER, C., GAS-SER, P., JENNINGS, D., Arizona State Uni-versity. Diversity and plasticity in corticoster-oid action.

Stressor-induced increases in plasmacorticosteroid (CORT) levels produce manyphysiological and neurochemical responsesthat serve, in large part, to facilitate appro-priate behavioral responses to imminentthreats. The behavioral responses to CORTare varied, being time-, context- and spe-cies-specific. Comparative studies can pro-vide insights into how a diversity of CORTreceptor mechanisms, involving neuronalmembranes, ligand-activated transcriptionfactors in neuronal cytosol, and plasma cor-ticosteroid binding globulins (CBG), contrib-utes to the diversity of behavioral responses.Neuronal membrane-associated receptorsappear to produce rapid changes in the pro-cessing of sensory or environmental infor-mation leading to acute behavioral transi-tions. Between species, the affinities of thesereceptors for CORT appears to be inverselyrelated to basal circulating levels of corti-costerone, making these receptors particu-larly well suited for responding to stress lev-els of CORT. The context specificity of rapidCORT action appears to be related to mem-brane receptor-mediated signaling mecha-nisms, particularly the pathways regulatedby behaviorally relevant neuropeptides.Seasonal differences in behavioral sensi-tivity to stressors may be mediated not onlyby seasonal differences in CORT release,but by seasonal plasticity in the numberCORT receptors in neuronal membranesand/or neuronal cytosol. Additional factorsin the plasticity of CORT action are the poorlyunderstood interaction of CORT with CBGsand the potential signaling activity of CBG.CBG, which regulates the circulating levels

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of free CORT, is regulated by multiple fac-tors in nonmammalian species includingseason, gonadal steroids, and social status.In several nonmammalian species, “CBGs”bind androgens with at least as high affinityas they bind CORT. Therefore, the binding ofCORT and androgens to the same moleculemay reciprocally regulate the relative con-centrations of free steroids, and this may beespecially significant during a stress re-sponse. In order to understand the adaptiveand deleterious actions of CORT, we needto consider the dynamics and plasticity ofcorticosteroid interaction with plasma, neu-ronal membrane, and intracellular bindingsites.

49.3 OWERKOWICZ, T.*, BRAINERD, E. L.,CARRIER, D. R., Harvard University, Cam-bridge, MA, University of Massachusetts,Amherst, University of Utah, Salt Lake City.Electromyographic pattern of the gular pumpin monitor lizards.

Gular pumping has recently been shownto play an important role in lung ventilationof monitor lizards but its evolutionary originhas not yet been investigated. To comparethis mechanism with the amphibian buccalpump, we studied the activity of throatmuscles during gular pumping in savannahmonitors (Varanus exanthematicus). We im-planted bipolar electrodes in hyobranchialmuscles, and recorded their firing patternsin synchrony with kinematic, airflow and pres-sure profiles of the gular pump. The monitorthroat is supported by a highly mobile hyoidapparatus, the unfolding and folding of whichproduces large volume air flows into andout of the gular cavity. Mm. sternohyoideusand branchiohyoideus expand the gularcavity, whereas mm. constrictor colli,intermandibularis and mandibulohyoideuscompress it. Closure of the choanae by sub-lingual plicae precedes gular compression,thus allowing positive pressure to be gener-ated in the gular cavity and air to be forcedinto the lungs. The gular pump is found toexhibit a neuromotor pattern identical to thebuccal pump of extant amphibians, and bothmechanisms involve homologous muscles.This suggests that the gular pump of moni-tor lizards may derive from the buccal pump

of basal tetrapods. Whether it does remainsto be determined by mapping gular pump-ing as a character on the squamate phylog-eny.

67.5 PABST, D.A.*, KOOPMAN, H.N.,ROMMEL, S.A., POTTER, C.W, READ, R.J.,MCLELLAN, W.A., University of North Caro-lina, Wilmington, Duke University, FloridaMarine Research Institute, Smithsonian In-stitution. Ontogenetic allometry and bodycomposition of harbor porpoises Phocoenaphocoena from the Western North Atlantic.

North Atlantic harbor porpoises face con-siderable energetic challenges, as they arerelatively small mammals with an intensereproductive schedule and a cold-waterhabitat. We describe post-natal growth ofporpoises using ontogenetic allometry andbody composition techniques. Our samplecontained robust calves, immature, andmature porpoises (n=122) killed in fishingoperations from 1992-98. Total mass andmasses of 26 body components were mea-sured using a standard dissection protocol.Most body components grew similarly in fe-male and male porpoises. Blubber, brainand skull grew negatively allometrically;muscle and reproductive tissues grew posi-tively allometrically. Female heart, liver, in-testines and mesenteric lymph node grewsignificantly faster than in males. Male loco-motor muscle and pelvic bones grew signifi-cantly faster than in females. High growthrates for visceral and reproductive organs inporpoises, relative to other mammals, mayunderlie their early maturation and supporttheir annual reproductive schedule. Rela-tive to other cetaceans, porpoises invest alarger percentage of their body mass in blub-ber. This large investment in blubber, whichis highest in calves (37% of body mass), mayprovide small-bodied porpoises the thermalinsulation required to live in cold, north At-lantic waters. The factors influencing growthrates and differential investments in bodycomposition, thus, appear to change at vari-ous stages of a porpoise’s life. Energetic in-vestment in porpoises shifts from an empha-sis on developing an insulative blubber layerin young animals to preparing the body forreproduction by the point of maturity.

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4.4 PACE, C.M.*, BLOB, R.W.,WESTNEAT, M.W., Field Museum, Chicago,IL. Comparative kinematics of the forelimbduring swimming in red-eared slider andspiny softshell turtles.

In freshwater turtles the hindlimb typicallyhas been viewed as the primary propulsiveorgan during swimming. However, in highlyaquatic softshell turtles, extensive webbingis present between the digits of the hand aswell as the foot, suggesting that the forelimbmay also serve as an effective paddle forgenerating drag-based thrust in these spe-cies. To test whether forelimb movements insoftshells also were consistent with a role inthrust production, we measured the three-dimensional swimming kinematics of theforelimb in spiny softshell turtles (Apalonespinifera) from digital video and comparedthese data with similar measurements fromred-eared sliders (Trachemys scripta), turtlesthat frequently travel on land and do not pos-sess webbed front feet. Several aspects offorelimb kinematics differ significantly be-tween these species. In general, the limbsegments move in a nearly horizontal planethroughout the stroke in softshells, but in slid-ers the humerus is raised as much as 30ƒabove the horizontal during protraction be-fore slicing down ventrally through the wa-ter during retraction. Peak elbow extensionduring the power stroke is nearly 50ƒ greaterin softshells than in sliders; in addition, theforefoot is oriented perpendicular to waterflow through nearly all of forelimb retractionin softshells, but only through the middle thirdof retraction in sliders. As a result of theselatter factors, softshells maintain a muchlarger surface area than sliders for drag-based propulsion with the forelimbs. Thus,the forelimbs could make much more sub-stantial contributions to forward thrust dur-ing swimming in highly aquatic softshellturtles than in more generalized turtles likesliders. NIH 5F32NS1081302 to RB andONR N000149910184 to MW.

35.2 PACKARD, G.C.*, PACK-ARD, M.J.,Colorado State University, Fort Collins. En-vironmentally induced variation in size andcondition of hatchling painted turtles.

We manipulated the contents of newlyconstructed nests of painted turtles

(Chrysemys picta) so that each of three nestsreceived two eggs from each of the samefive females. The manipulation was repli-cated on three successive days, therebyyielding a sample of nine nests and 15clutches. The eggs then were allowed toincubate in the field for 54-56 days beforethey were brought into the laboratory to com-plete incubation at an optimal temperatureand water potential. Both clutch and nestcontributed significantly to variation in sizeand condition of hatchlings. Embryos ineggs that absorbed water from the nest en-vironment mobilized more of the lipid andprotein from their yolk and grew larger be-fore hatching than did embryos in eggs thatlost water to the surroundings. The relativelylarge hatchlings contained more storagelipid than did smaller animals, but the lipidreserve scaled with body size. Our findingspoint to an important role for water in modu-lating the metabolism and growth of embry-onic turtles developing under natural condi-tions in the field. Supported by NSF (IBN-9612562).

29.1 PACKARD, M.J.*, PACK-ARD, G.C.,Colorado State University, Fort Collins. Whyhatchling painted turtles overwinter in theirnest.

We placed hatchling painted turtles(Chrysemys picta) individually into pint-vol-ume canning jars containing damp soil orartificial pond water and then exposed theanimals to 4oC in a simulated hibernationlasting 70 days. Our goal was to gain newinsight into why baby painted turtles remaininside the natal nest for the first winter oftheir life and thereby expose themselves topotentially lethal conditions of ice and cold.The usual explanation for this behavior holdsthat hatchlings remaining in their nest overthe winter minimize their exposure to preda-tors at a time of year when the potential forgrowth is low. However, few of the turtles inour experiment survived 70 days of immer-sion in pond water whereas all the animalssurvived for 70 days in soil. Hatchlings inpond water may have succumbed to osmo-ionic imbalance, insufficiency of gas ex-change, or some unidentified factor. Never-theless, the overwintering behavior of neo-natal painted turtles may be related to limi-

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tations of their physiology and not to somereduction in the risk of predation. Supportedby NSF (IBN-9612562).

31.4 PADIAN, K.*, HORNER, J.R., deRICQLES, A., University of California, Ber-keley, Montana State University, Bozeman,College de France, Paris. Dinosaurian lifehistory strategies: evidence of differentialgrowth rates from bone histology.

Dinosaurs, like other tetrapods, grewmore quickly shortly after hatching than laterin life. However, they did not grow like othernon-avian reptiles, slowing their trajectorygradually in a convex arc through ontogeny.Rather, dinosaurs (especially large ones)grew to their adult size relatively quickly,much like large birds and mammals do to-day. Some large duckbills took only sevenyears to reach seven meters in length; somelarge sauropods may have taken only a de-cade to reach full size. Gigantic crocodilesof the past, in contrast, grew along the growthtrajectory of living crocodiles, but simply ex-tended and attenuated the growth curve.They may have taken several decades toreach tens of meters in length. Large ptero-saurs apparently grew much like large birdsand other large dinosaurs. But small ptero-saurs and some small dinosaurs apparentlygrew at slower rates after hatching, compa-rable to fast-growing rates in crocodiles, judg-ing from bone tissue structure and vascular-ization. Theropod (carnivorous) dinosaursseem to have grown very quickly from theirearly evolution, regardless of size. The firstbirds apparently slowed growth rates butmaintained shape trajectory to produce asmaller adult size; only later in avian historywas small size attained quickly.

7.6 PADILLA, D.K., DILGER, E.K.,DITTMANN, D.E., SUNY Stony Brook, WardMelville High School, USGS/Tunison Labo-ratory of Aquatic Science. Phenotyic plastic-ity of feeding structures in species ofLittorina.

Several species of gastropods in the ge-nus Lacuna, Family Littorinidae, have beenfound to have phenotypically plastic feed-ing morphologies. Animals fed different di-ets produce different shaped radular teeth.When fed diatom epiphytes found on eel-

grass, snails produce blunt-shaped teeth.When fed macroalgae (kelps, ulvoids, orbladed red algae) they produce pointed-shaped teeth. Experiments were performedwith three species of Littorina, with differentdevelopment patterns, to see if they wouldrespond in a similar fashion as Lacuna.Littorina littorea has plaktotrpohic develop-ment, Littorina obtusata lays benthic eggmasses and has crawl away juveniles, andLittorina saxatilis is viviporous. We fed indi-viduals of each species one of two diets,either diatom epiphytes or the green alga,Ulva lactuca, for 6 weeks and then exam-ined their radulae. For each individual wedeteremined the shape of the theeth on theanterior (older) portion of the radula and theposterior (younger) portion. Differences intooth shape along the length of the radula ofan individual was used to determine if toothmorphology was phenotypically plastic. Wefound that two species were phenotypicallyplastic, but the third was not. Of the two spe-cies that were plastic, only one showed asignificantly different response to diet.

63.1 PAGE, L.R., University of Victoria. Theapical sensory organ of gastropod larvae:new data on a patellogastropod.

The larval nervous systems of annelidand molluscan larvae include an apical clus-ter of sensory and non-sensory neurons thatis often associated with a tuft of long cilia.Some of the neurons show immunoreactiv-ity to serotonin and the structure includes aneuropil adjacent to the cerebral commis-sure. In gastropods, this apical sensory or-gan (ASO, also called apical ganlgion) maycontrol activities of muscles and cilia of thevelum and also may be involved in initiatingor coordinating metamorphosis. Detailedcomparative analyses of this structure mayyield characters having value for phyloge-netic reconstructions and may provide in-sights about its function. Among gastropods,the ASO of a number of caenogastropodsand hetero-branchs have now been de-scribed, but the ASO of more basal gastro-pod clades has not been investigated. I de-scribe the structure of the ASO in severallarval and post-larval stages of apatellogastropod, a group that may be the

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most basal clade of gastropods having liv-ing descendants. My observations arebased on scanning and transmission elec-tron microscopy and on immunohistochemi-cal techniques for detecting serotonin anti-genicity. The ciliary tuft associated with theASO of Tectura scutum is lost soon after on-togenetic torsion and the neuronal clusterincludes at least one and possibly three neu-rons showing immunoreactivity to serotonin.A serotonergic axon emerges from each sideof the ASO and extends along the base ofthe prototrochal ciliary cells of the velum.These characteristics and additional ultra-structural features of the ASO of T. scutumwill be compared to the ASO of thecaenogastropod and heterobranch larvaethat have been studied to date.

13.5 PAK, T.R.*, LYNCH, G.R., TSAI, P.-S.,University of Colorado. Testosterone and es-trogen act via different pathways to inhibit pu-berty in male Siberian hamsters.

Testosterone (T), dihydrotestos-terone(DHT), and 17b-estradiol (E) induce testicu-lar regression in peripubertal, male, Sibe-rian hamsters, Phodopus sungorus. SinceT can be converted to DHT or E, whether Tacts directly or through its metabolites to in-hibit gonadal development is not known. Thepurpose of this study was: 1) to determine ifT, DHT, and E have differential effects on thehypothalamic-pituitary-gonadal axis (HPG);and 2) to determine if peripubertal hamstersshow a change in sensitivity to T inhibitionfollowing the pubertal transition. In Experi-ment 1, pre-pubertal hamsters were im-planted with a capsule containing crystal-line T, DHT, E, or cholesterol (Ch). After 15days, blood, hypothalami, pituitaries, andtestes were collected. In experiment 2, pre-pubertal animals were implanted with T orCh, castrated at 35-days of age, and implantwas removed at 45-days of age. The im-plant was replaced 5 (Group A) or 10 (GroupB) days post implant removal. Results fromExperiment 1 showed E significantly reducedpituitary FSH content but not T or DHT.Plasma FSH content was undetectable in Tand DHT groups but E-treated animals weresimilar to controls. Experiment 2 showedthat plasma FSH levels were undetectable

in T-treated animals until implant removal.FSH levels rise significantly as early as 1-day post-implant removal. Plasma FSH wasundetectable following re-implantation inGroup A, whereas they remained signifi-cantly higher in Group B. Taken together,our data showed that T and E act via differ-ent pathways to inhibit the HPG axis duringpubertal maturation in the male Siberianhamster. Further, a decrease in the sensitiv-ity to T-induced HPG inhibition occurred dur-ing a defined period immediately after theperi-pubertal transition. Supported by NSFgrant IBN-9996398

P3.16PANKO, L.J., University of Chicago, IL.How to distinguish the basal triassiccynodonts Galesaurus and Thrinaxodon fromone another using rib morphology.

A peculiar feature of certain non-mam-malian cynodonts is their broad, overlappingribs. Galesaurus and Thrinaxodon havebroadened ribs in both thoracic and lumbarregions, though the details of morphologyvary along the trunk. In the past, Galesaurushas been reconstructed as having the samepattern of rib morphology as occurs in thebetter-known genus Thrinaxodon. Cynodontspecimens BP/1/3911 and BP/1/4506 at theBernard Price Institute, South Africa, revealfeatures in the mid-dorsal and lumbar ribs ofGalesaurus that clearly distinguish them fromthe ribs of Thrinaxodon. Mid-dorsal ribs ofGalesaurus have a caudally-projecting lobeof bone approximately as long as it is wide,whereas mid-dorsal ribs of Thrinaxodonhave a projecting shelf of bone that is trans-versely wider than long. The lumbar ribs ofGalesaurus are expanded cranio-caudally,with a roughly oval shape in lateral view.The lumbar ribs of Thrinaxodon are less elon-gated cranio-caudally, with a roughly squareshape in lateral view. The presence of dis-tinct variation in rib morphology betweenthese two genera indicates that among non-mammalian cynodonts, ribs may be of usein (1) identification of skeletons when theskull is incomplete or missing, (2) phyloge-netic analyses, and (3) functional interpre-tation of axial skeleton evolution.

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29.6 PARHAM, J.F., University of Califor-nia at Berkeley. New perspectives on theorigin(s) of marine turtles.

Because they share a large number ofmorphological characters, living marineturtles (Chelonioidea) are thought to haveevolved from a single ancestor. Allchelonioids share paddle-like limbs, a re-duced shell, and peculiar arterial perfora-tions of the braincase. However, compara-tive studies of distantly related clades thatinhabit marine or open waters shows thatmany of these characters are correlated toecology and mode of locomotion. For ex-ample, besides chelonioids, the livingCarettochelys is the only other turtle with asymmetrical underwater flight stroke and itshares many limb characters consideredsynapomorphies of marine turtles. Further-more, the phylogenetic analyses of long-ne-glected Asian fossils shows that many of theother characters are actually primitive - lostby other living turtles, but retained inchelonioids. Taken together, these data castdoubt on the hypothesis of monophyly. Anindependent line of evidence for multiple ori-gins is the first appearances of marine turtleclades in the fossil record. Marine sedimentspreserve the pulses of separate radiationsas morphologically primitive turtles becamemore specialized and diverse. The timing ofthese appearances is congruent with a mul-tiple origin hypothesis because some puta-tive sister taxa are separated by about 50million years. Finally, when marine-relatedcharacters are removed, the morphology ofthe primitive members of these groups cor-responds to the morphology of coeval ter-restrial lineages. The turtle bauplan is gen-erally conservative, and the interaction of hy-drodynamic and ontogenetic factors mayhave contributed to similar iterations of char-acter complexes in marine turtles.

66.4 PARHAM, J.F.*, SIMISON, W.B.,KOZAK, K.H., FELDMAN, C.R., University ofCalifornia at Berkeley, University of Califor-nia Museum of Paleontology, University ofWashington at St. Louis, University of Wash-ington at St. Louis. A reassessment of somerecently described Chinese turtles.

Over the past 16 years, herpetologists de-scribed 13 new species of turtles. Most of these

are based on specimens purchased from thepet trade. Herpetologists collected only two ofthese species, the rest have not been observedin the areas and habitats in which they werereported to occur. Questions have been raisedabout the validity and conservation of theserare and putatively endangered turtles. Weused mitochondrial DNA and allozyme elec-trophoresis to test the validity of two of thesenew species (Mauremys iversoni and Cuoraserrata). Both lines of evidence support theidea that these turtles are intergeneric hybrids.This hypothesis is consistent with the morphol-ogy of these turtles, which is intermediate be-tween the two genera. Serious issues remain.Other “new” turtle species require intensive in-vestigation: Whereas some are probably validspecies worthy of conservation, others may beturtle farm hybrids. The parent species ofMauremys iversoni are common in turtle farms,and the accidental production of this “species”has been documented. But the parent speciesof C. serrata are not farmed. In fact, the lattermay be a naturally occurring hybrid. We can-not assume that all the hybridization is an-thropogenic, but how do we separate natu-ral hybridization from husbandry? The abil-ity of turtles to hybridize readily is well docu-mented. Could reticulation be a commonsource of new species in turtle evolution?New observations from China suggest thatmost of the new “species” are artifically pro-duced.

P2.26PARK, D.S.*, PROPPER, C. R., North-ern Arizona University, Flagstaff. Purificationand action of a repelling pheromone frommale red-spotted newts.

Male red-spotted newts, Notopthalmusviridescens, interacting with females releaserepelling pheromones that function to repelconspecific males. It has suggested that therepelling pheromones may conserve boththe courting and approaching (towards acourting group) males’ reproductive fitnessby controlling the sex ratio within the court-ing arena. Using behavioral bio-assays, col-umn-chromatography, and SDS-PAGE, wehave begun to purify the repelling phero-mone. Also, the pathway for the action of therepelling pheromone in male olfactory or-gan was investigated using an electro-olfacto-gram (EOG) analysis. We found that

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1) the repelling pheromone is produced frommale cloacal glands, 2) the repelling phero-mone is protein of approximately 37 kda,and 3) the repelling pheromone induceshigher olfactory response from the vomero-nasal system than the main olfactory organof male newts. These results suggest thatthe proteinacious repelling phromone in-duces repelling responses from conspecificmales via the vomeronasal organ. The Coun-cil of Tobacco Research, USA (#4601811)to C.R.P supported this work.

P3.60PARK, S.C.*, CHO, S.J., LEE, M.S.,CHO, P.Y., KOH, K. S., Chung-Ang Univer-sity, Chung-Ang University, Chung-Ang Uni-versity, Chung-Ang University, Kon-Kuk Uni-versity College of Medicine. Developmentalchanges of Blastema and Proteinase activi-ties during earthworm tail regeneration.

Developmental Changes of Blastemaand Proteinase Activities during EarthwormTail Regeneration Sung Jin Cho, Myung SikLee, Pyo Hyun Cho and Soon Cheol ParkDepartment of Life Science, Chung-AngUniversity, Seoul 156-756, Korea Althoughthe earthworm is an important animal spe-cies capable of regenerating missing bodypart, earthworm regeneration is not well un-derstood at the tissue, cell and molecularlevels. In order to understand the develop-mental changes of blastema and the signifi-cance of proteinase activity during earth-worm tail regeneration, the formation anddevelopment of blastema and the charac-teristics of proteinases induced during re-generation were investigated by histologi-cal and zymographic analysis. By histologi-cal observation, we have identified that amajor origin of earthworm blastemal cells isthe longitudinal muscle layer of body wall.Blastema formed beneath wound dermiswas segmented and then redifferentiated.Zymographic analysis of proteinase re-vealed that at least four types of proteinaseswere induced during tail regeneration, whichhad molecular weight of 25, 28, 38, and 44kDa, respectively. Proteinase activities werebegun to increase within 24 hrs after ampu-tation. All types of proteinase activities in-duced during tail regeneration were stronglyinhibited by treatment of PMSF and aprotininbut not by pepstatin A, E-64, iodoacetamide

and metal ion free-medium, indicating thatthey are serine proteinases. By fibrin autog-raphy, we have detected an elevation ofplasminogen activator (PA) just prior to serineproteinase peaks, suggesting that theseserine proteinases would be a member ofplasmin.

P3.27PARKER, S.C.J., daSILVA, J.,STELLWAG, E.J.*, East Carolina University.Computational method for identification offunctionally significant non-coding se-quences: studies of Hox cluster organiza-tion.

A question of considerable interest toevolutionary developmental biologists isthe linkage between Hox gene architec-ture and spatio-temporal expression pat-terns during embryogenesis. The prevail-ing hypothesis is that this linkage resultsfrom a network of interacting cis-regula-tory elements that compete for and sharethe transcriptional regulatory apparatus ofclustered Hox genes. There are two im-portant corollaries of this hypothesis thatwe are addressing. 1) If the clustered ar-chitecture of the Hox complex is depen-dent on the sharing and competition be-tween cis-regulatory elements, then theelements should be functionally significantand undergoing purifying selection. 2) Thenetwork of regulatory elements within eachcluster should be sufficiently extensive toaccount for the evolutionary maintenanceof linkage between the clustered architec-ture and spatio-temporal expression pat-terns. We have developed a computationalmethod to identify functionally significantnon-coding seqeunces; i.e. sequencesunder purifying selection and used it toexamine non-coding sequences both up-stream and downstream of the Hoxb7apseudogene in teleosts. Our results dem-onstrate the occurrence of an extensivenetwork of intergenic sequence domainsundergoing purifying selection in the neigh-borhood of the Hoxb7a pseudogene. Thesignificance of the sequence domainsidentified is underscored by the fact thatone of the domains identified in our analy-sis has previously been shown to bepresent on all Hox clusters in the samerelative position. We believe our method

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provides an opportunity to use compara-tive genomic analyses to reveal function-ally significant non-coding sequences.

P3.35PARMENTIER, E.*, LAGARDERE, F.,DIOGO, R., VANDEWALLE, P., University ofLiëge, Belgium, CREMA L’Houmeau,CNRS-IFREMER, France, University ofLiëge, Belgium, University of Liëge, Belgium.Study of the otoliths and otic area incarapidae fishes : eco-morphological impli-cations?

Carapidae-family species arecharacterised by so-called oto-physicalstructures (sonic muscles, broad first apo-physes covering the anterior part of theswimbladder, etc.) The family includes pe-lagic (e.g. Pyramodon sp.) and benthic(e.g. Echiodon sp.) species and ones thatare either commensal (e.g. Carapus sp.)or parasites of (e.g. Encheliophis sp.) in-vertebrates (sea cucumbers, etc). The aimof the work is to seek possible relation-ships between the structures of the innerear on the one hand and otophysical struc-tures and lifestyles within the Carapidaefamily. In the eight species studied, theotic cavity is wide, the saccular otosac andits sagitta are particularly developed. Thesacculi touch each other on the medianline. A comparison of the inner ear struc-tures reveals notably that the species withthe most developed sagitta and sacculusare those with the largest parapophyses.These structures, both auditory and oto-physical, are most developed in speciesthat are not completely free-swimming, i.e.,with a commensal or especially a para-sitic lifestyle.

53.5 PARSONS, J.L.*, HELLGREN, E.C.,LOCHMILLER, R.L. (deceased), LESLIE,D.M., JR., JORGENSEN, E.E., OklahomaCooperative Fish and Wildlife Research Un,Oklahoma State University, Stillwater, Okla-homa State University, Stillwater, OklahomaCooperative Fish and Wildlife Research Un,U.S. Environmental Protection Agency, Ada,Oklahoma. Protein nutrition of Southernplains small mammals: comparative nitro-gen requirements for reproduction.

Nitrogen nutrition and dynamics in ani-mal communities are of increasing interest,

given growing amounts of nitrogen in ter-restrial and aquatic systems and the role ofnitrogen as an essential nutrient. We per-formed feeding trials on two small mammalspecies (the hispid cotton rat, Sigmodonhispidus, and the fulvous harvest mouse,Reithrodontomys fulvescens) to determinenitrogen requirements for reproduction. Be-cause of the relatively low-protein diet of wildcotton rats, we predicted that S. hispiduswould have a lower nitrogen requirementthan R. fulvescens. Females were fed oneof seven experimental diets (1% to 3.5% ni-trogen) from the third trimester ofgestationthrough lactation. Offspring were weighedevery other day from birth until weaning, andpup growth rate was regressed on maternalnitrogen intake. A break-point analysis wasperformed to determine each species’ re-productive requirement. Our data indicatethat S. hispidus required 2.47% dietary ni-trogen (2731.08 mg/kg0.75) and R. fulvescensrequired 1.69% nitrogen (2258.48 mg/kg0.75)for maximal reproduction. Although our pre-diction was not upheld, the use of maximumreproductive output to define nitrogen re-quirements may not reflect the reality of free-ranging animals. Results will be discussedwith regard to interspecies comparisons, di-etary niche and life-history strategies, andalternate analyses will be proposed to find amore ecologically relevant definition of re-productive requirements.

5.5 PASSAMANECK, Y.J.*, HALANYCH,K.M., MIT/Woods Hole Oceanographic In-stitution Joint Prog, Woods Hole Oceano-graphic Institution. Lophotrochozoan rela-tionships inferred from 28s rDNA se-quences.

28S rDNA has been sequenced from avariety of taxa to investigate evolutionaryrelationships within the Lophotrochozoa.The clade Lophotrochozoa, which in-cludes annelids, mollusks, and the threelophophorate taxa (bryozoans, brachio-pods, and phoronids), was first identifiedbased based upon analysis of 18S rDNA.Analyses of 18S rDNA has also suggesteda polyphyletic origin for the lophophorates,with bryozoans branching seperately frombrachiopods and phoronids. Despite iden-tifying these novel groupings, the ability of

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18S rDNA sequences to resolve relation-ships between the major taxa within theLophotrochozoa appears to be limited.Preliminary results suggest that full-length28S rDNA sequence provides more char-acters for phylogenetic reconstruction thandoes 18S rDNA. Increased resolution ofrelationships between lophotrochozoantaxa provides an important framework forunderstanding character evolution withinthe Lophotrochozoa.

P1.48PATE, S.E.*, CHECK, J.F., ROER, R.D.,MOUSTAKAS, C.T., University of N.C. atWilmington. Effects of size and salinity onsodium and water permeability inCallinectes sapidus.

In order to understand the magnitude ofthe osmoregulatory stress imposed uponjuvenile blue crabs in low salinities, the wa-ter and sodium permeabilities of these crabswere measured after acclimation to eithersea water (1000 mOsm) or dilute sea water(150 mOsm) and compared to adult and sub-adult specimens. Crabs were incubated intheir acclimation medium to which either3H2O or 22NaCl was added. After at least 24h equilibration, washout of the isotope wasmonitored into non-radioactive media. Therate of passive efflux was used as an indexof relative permeabilities. In all cases, therewas an inverse logarithmic relationship be-tween size and permeability, typical of meta-bolic rate scaling functions. Acclimation to150 mOsm induced a decrease in Na per-meability for crabs of all sizes, but the de-crease was greater for juvenile crabs thanfor adults. Water efflux was unchanged inboth adult and juvenile crabs acclimatedto150 mOsm relative to the rate in sea water.Because the osmotic gradient is much largerat low salinity, these data reflect a decreasein water permeability. While juvenile crabsare capable of marked reductions of Na andwater permeability in low salinities, the datasuggest that this is not sufficient to completelyoffset a higher metabolic cost associated withosmoregulation relative to adults.

S12.8PATRICK, M.L.*, BRADLEY, T.J., Uni-versity of California, Irvine. Salt-lovin’skeeters: the osmocon-forming strategy ofmosquito larvae.

Culex is a genus of mosquito that pos-sesses both freshwater restricted (e.g. C.quinquefasciatus) and euryhaline larvae(e.g. C. tarsalis), the latter being able totolerate up to 70% full strength seawater.While held in freshwater conditions, boththe euryhaline and the freshwater-re-stricted species are hyperosmotic regula-tors and maintain similar hemolymph ionconcentrations. However, when environ-mental osmolality is raised using salts, C.quinquefasciatus cannot survive whereasC. tarsalis employs the osmoconformingstrategy, in which hemolymph osmolalityconforms to the environment thereby elimi-nating the gradient for water loss. Follow-ing an acute increase in environmental sa-linity, the larva of C. tarsalis, regulate bodyvolume by increasing their drinking rate ofthe external medium. Increases inhemolymph Na and Cl concentrations areattenuated by the differential stimulationof Na efflux and reduction of Cl influx. Therise in hemolymph osmolality during ac-climation to higher salinity is attributed tothe accumulation of two organicosmolytes: the amino acid proline and thedisaccharide trehalose. Hemolymph pro-line levels increase almost 50 fold and tre-halose accumulates two fold from fresh-water values. Additionally, proline is ac-cumulated intracellularly to levels equiva-lent to that found in the extracellular com-partment (hemolymph), the first such casereported in salt-tolerant animals. By ma-nipulating environmental osmolality usingsalts, compatible solutes (sorbitol), or acombination thereof, we determined thatproline accumulation is cued by changesin hemolymph NaCl whereas trehalosefollows environmental osmolality. Thesource for the proline accumulation dur-ing the osmoconforming response is notfrom hemolymph proteins but rather thestimulation of proline synthesis fromglutamate. Funded by NSF grant IBN9723404.

P1.42 PAULSEN, R.S.*, WEIHRAUCH,D., LIGNOT, J.-H., TOWLE, D.W., Lake For-est College, IL and Mt. Desert Island Biol,University Montpellier II, France. Na,K-ATPase in gills of the blue crab Callinectes

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sapidus: cDNA sequencing and salinity-related expression of alpha subunit mRNAand protein.

Many studies have shown thathyperosmoregulation in euryhaline crabsis accompanied by enhanced Na,K-AT-Pase activity in posterior gills, but it is notclear whether the response is due to acti-vation of pre-existing enzyme or to in-creased gene transcription and mRNAtranslation. To address this question, thecomplete open reading frame and 3'untranslated region of the mRNA codingfor the ALPHA subunit of Na,K-ATPasewere amplified and sequenced by RT-PCR.The resulting 3,433-nucleotide cDNA en-codes a putative 1,011-amino acid proteinwith a predicted molecular mass of 112.5kDa. Hydrophobicity analysis of the aminoacid sequence indicated eight membrane-spanning regions, in agreement with pre-viously suggested topologies. The ALPHAsubunit amino acid sequence is highly con-served among species, with the blue crabsequence showing 81-83% identity toother arthropods and 74-77% identity tovertebrate and non-arthropod invertebratespecies. Semi-quantitative PCR showedhigh levels of ALPHA subunit mRNA inposterior gills 6-8 compared with anteriorgills 3-5. Western blots of gill plasma mem-branes revealed a single Na,K-ATPaseALPHA subunit protein band of the ex-pected size. Posterior gills contained amuch greater level of ALPHA subunit pro-tein compared with anterior gills, in agree-ment with historical measurements of en-zyme activity. Transfer of blue crabs from35 to 5 ppt salinity was accompanied bymodest increases in ALPHA subunitmRNA and protein in posterior gills, pro-viding a molecular explanation for the en-hanced Na,K-ATPase enzyme activity thataccompanies the hyperosmoregulatoryresponse. Supported by NSF (IBN-9807539).

P2.95 PAVLOV, V., Crimean State Uni-versity of Medicine. Morphological adap-tation of dorsal fin of harbour porpoise(Phocoena phocoena) to swimming andthermal regulation function.

Dorsal fin is an example of particular

specialization of an organ having com-bined function of stabilization of motion andheat regulation. The shape of the fin wasevaluated by the set of wing and foil pa-rameters: angle of leading edge sweep,leading edge radius, maximum thicknessof the foil, position of maximum thicknessfrom the leading edge. The distribution ofthickness of epidermis, papillary and sub-papillary layers of dermis, ligamentouslayer of fin as well as dermal ridges direc-tion, 3D structure of dermal-epidermaljoint, central core structure and character-istic features of the blood system of dorsalfin had been studied. It was found thatmorphology parameters of dorsal fin de-pend on wing and foil parameters. Sincethe skin structure is the base of the skinmechanical properties, the founded regu-larity can be considered as an indirectevidence of correspondence of passivemechanical properties of the surface to thefin flow. The central core structure assignssmooth decrease of the rigidity of dorsalfin in chordwise and spanwise directions.Ligamentous layer being elastic and al-most not extensible braid of fin preventsfrom excessive bending in these directions.The characteristic feature of dorsal finblood system consists in existence of com-bined vessels in the central core, wherethe braid of veins surrounds arteries aswell as the system of big veins beneaththe ligamentous layer. Such characteristicprovides an effective heat exchange be-tween venous and artery blood as well astransfer of the heat redundancy into theenvironment. Dorsal fin design is the com-promise between wing performance andrequirements of thermal regulation.

17.3 PEDERSEN, S.P., South Dakota StateUniversity. The impact of volcanic eruptionson the bat populations of Montserrat, BWI.

Hurricanes and volcanic eruptions havehad significant impacts upon the bat popu-lations of Montserrat, underlined by the lossof 3 of its 10 species:Chiroderma, Sturnira,Noctilio. Seven surveys have documentedpopulation decreases following HurricaneHugo in í89 and the Soufriere Hills volcanosince ë95. Apart from the minor inconve-

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nience of being incinerated by pyroclasticflows (500 C), the fruitbats of Montserrat havecontended with acid rain, the deposition ofvolcanic ash on fruits/flowers (and its sub-sequent ingestion), and the accumulation ofash on the animals pelage whilst foraging.Volcanic activity has declined during the lasttwo years. and fruitbat populations have re-bounded slightly as estimated by bat cap-tures per net-night. There was a focal in-crease in sub-lethal pathologies associatedwith ash-fall during peak volcanic activity(95-98). Before the onset of activity, 3/641 (<1%) fruit bat captures exhibited tooth wear.Since 1995, 35/190 (18%) fruit-bats exhib-ited abnormal wear and/or dental attrition.Occlusal surfaces of remaining teeth exhibitabnormal wear, advanced dramatically bythe incidental ingestion of volcanic ash whilefeeding and grooming. Idiopathic hair-loss(alopecia) had only been observed once in638 captures before ë95. Alopecia was fre-quently (30-60%) recorded for allBrachyphylla, Artibeus, and Ardops in ë97-í98. This alopecia is likely related to roost-parasitism, and possible mineral deficien-cies associated with ash ingestion. During2000, alopecia was noted only in femaleBrachyphylla. Our survey of the adjacent is-land of Antigua provides an interesting con-trol for the biogeography and natural historyof Montserratian bats. Antigua has not beenaffected by volcanic ash, nor have our sur-vey efforts identified a single case of alope-cia or extreme tooth wear.

P3.58A PERFITO, N.*, MEDDLE, S.L.,SHARP, P.J., WINGFIELD, J.C., University ofWashington, University of Edinburgh Medi-cal School, Roslin Institute, University ofWashington. Seasonal gonadal recrudes-cence in song sparrows (Melospizamelodia): response to temperature cues.

Reproduction is timed so the likelihoodof offspring survival is optimal, and for sea-sonal breeders often coincides with peaksin food abundance. Changing of the sea-sons is predictable at mid-latitudes, andspring is forecasted by lengthening days inwinter. However, additional environmentalcues (e.g. temperature, rainfall) give moreprecise information about when subsequent

food peaks will occur. We tested the effectsof temperature on the seasonal reproduc-tive development of male song sparrows(Melospiza melodia morphna) from twopopulations: the coast of Western Washing-ton (3 m) and the Cascade Mountains (1600m). In the field, the timing of gonadal recru-descence can differ between the two popu-lations by as much as two months, but in thelab under identical conditions, testes growat the same rate. To investigate the role oftemperature on the rate of gonadal growth,we captured birds from each population andassigned them to one of two treatmentgroups (2x2 design). We held birds in tem-perature controlled environmental cham-bers that either mimicked temperatures ex-perienced in the mountains or on the coast.We increased daylength on a natural sched-ule in all groups, and measured testis vol-ume, levels of circulating testosterone andprolactin, and song rates. Increasingdaylength stimulated gonadal growth in allgroups. Only in the mountain birds did colder,montane temperatures produce slowedrates of gonadal growth, delaying the onsetof growth by one month when compared toall other groups. Since temperature changesmore markedly during the early winter monthsin the mountains than on the coast, increas-ing temperature may be a more relevant cuein timing of reproduction in the mountainpopulation.

S9.7 PERRIN, M.H., LEE, K-F., BALE, T.*,LEWIS, K., VAUGHAN, J., VALE, W., The SalkInstitute. Diverse roles of corticotropin releas-ing factor receptors and their ligands.

Corticotropin releasing factor, CRF, playsa major role in homeostasis by mediatingthe endocrine, autonomic, immune and be-havioral responses to stress. The actions ofCRF result from activation of its receptors,CRF-R1 and CRF-R2, which are encodedby distinct genes and belong to the family of7-TMD receptors which includes those forGRF, secretin, calcitonin and PTH. The re-ceptors couple to GTP-binding proteins andactivate adenylate cyclase. CRF-R1 is widelyexpressed in the central nervous system andalso in the pituitary, gonads, thymus andadrenals. One splice variant of CRF-R2 is

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expressed mainly in the central nervoussystem while the other variant is appears inthe heart, skeletal muscle, epididymis andGI tract. The second mammalian CRF-re-lated peptide, urocortin, Ucn is found in manybrain areas and also in the heart, GI tractand immune system, regions of high expres-sion of CRF-R2. Pharmacology of the CRFligand family, including (fish) urotensin, (frog)sauvagine and (insect) diuretic hormoneshow that all the CRF ligands bind with simi-lar high affinity to CRF-R1, but urocortin,urotensin and sauvagine are more potentthan CRF for CRF-R2. Ucn is a potent anti-inflammatory agent, modulates vasculartone, displays cardiovascular effects, andacting centrally, reduces appetite and foodintake. Transgenic mice lacking functionalCRF-R1 display impaired stress responses,reduced anxiety and lack of acute anorecticeffect of Ucn. In contrast, CRF-R2 knock-outmice show hypersensitivity to stress, anxi-ety-like behavior, reduced food intake fol-lowing food deprivation and lack of Ucn-in-duced hypotension. The future holds prom-ise for discovering new CRF ligands andreceptors and further understanding of theirmanifold physiologic roles.

38.6 PERRY, G.*, GARLAND, T., JR., Uni-versity of Wisconsin, Madison. Lizard homeranges revisited: traditional and phylogeneticperspectives.

Home range (HR) is the area traversedduring food gathering, mating, and other rou-tine activities. Thus, it is an ecologically im-portant indicator of the behavioral and re-source requirements of an animal. We re-evaluated the factors affecting estimates ofHR area in lizards. We compiled a databaseof over 470 published sex X population datasets. After removal of incomplete sets, weanalyzed data representing 103 populationsfrom 58 species. Conventional nested analy-sis of covariance, which treats each datapoint as statistically independent, showedhighly significant effects of all factors andcovariates tested, including both biological(diet, habitat type, body size, sex) and meth-odological (calculation method, number ofsightings) ones. Addition of basic phyloge-netic information (major and minor clade) tothe statistical model produced similar con-

clusions. HR did not significantly differ be-tween members of Autarchoglossa andIguania, but the differences among families,nested within these two major clades, werehighly significant. To account for possiblephylogenetic non-independence, we alsoanalyzed the data with independent con-trasts (Felsenstein, 1985, Am. Nat. 125:1-15;Garland, Midford, and Ives, 1999, Am. Zool.39:374-388), and a phylogeny assembledfrom published studies. This analysis pro-duced similar results: diet, habitat type, bodysize, and calculation method had significanteffects for both sexes, but no differenceswere detected between Autarchoglossa andIguania. The allometric slope for HR areawas similar to that for the scaling of field meta-bolic rates of lizards (Nagy, Girard, andBrown, 1999, Annu. Rev. Nutr. 19:247-277).NSF IBN-9723758.

P3.7A PESAVENTO, J.J.*, NEAR, T.J.,CHENG, C-H.C.; University of Illinois,Champaign-Urbana, University of Illinois,Champaign-Urbana, University of California,Davis. The phylogenentic investigations ofthe Perciformes (Actinopterygii) and the ori-gin of the Antarctic Notothenioidei: infer-ences for mitochondrial and nuclear DNAsequences.

Comprising approximately 9,300 species,the Perciformes represents the largest orderof vertebrates. Perciform fishes are the domi-nate component of vertebrate ocean life. TheAntarctic fishes of the Notothenioidei areclassified as sub-taxon of the Perciformes.Assessment of notothenioid monophyly iscomplicated by the lack of resolute phyloge-netic hypotheses for perciform fishes. Mor-phological characters have been unable tounambiguously discriminate among alterna-tive hypotheses due to the lack of informa-tive character states and a propensity of con-vergent evolutionary trends. DNA sequencedata provides an alternative strategy to esti-mate phylogenetic relationships, especiallywhen morphological characters are uninfor-mative or misleading with regards to recon-structing relationships. In this investigationwe have gathered a preliminary samplingof perciform diversity to assess the phyloge-netic utility of two mitochondrial genes (16sribosomal and cytochrome b) and a single-

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copy nuclear gene (titan). These analysesare used to test hypotheses of perciform re-lationships based onmorphology, determineif the Notothenioidei represents a mono-phyletic lineage, and attempt to identify thesister taxon of the Notothenioidei.

30.4 PETERSON, C.C.*, HUSAK, J., Okla-homa State University, Stillwater. Sexual se-lection and dimorphism of morphology andlocomotor performance in a polygynous, ter-ritorial lizard.

Integrative, whole-animal traits such aslocomotor performance could, in theory,evolve via sexual selection. Predictions ofthis hypothesis include: 1) such a second-ary sexual performance characteristicshould be sexually dimorphic in adults, butnot in juveniles, 2) proximate morphologi-cal correlates of performance should varysimilarly, and 3) variation in performanceamong males should be correlated tomating success. We tested these predic-tions in a population of the polygynous,male-territorial lizard Crotaphytus collaris.Maximal sprint performance was mea-sured on a computer-timed racetrack incomplete ontogenetic series of wild-caughtmale and female collared lizards. Individualvariation in sprint speed was highly re-peatable. Sprint speed scaled to bodysize, but was not consistently correlatedwith any other morphological characteris-tics once body size was accounted for.Contrary to our prediction, size-relativesprint speed did not differ between sexesin any size class. In contrast, adult lizards(but not juveniles) were strongly sexuallydimorphic for several morphological char-acteristics, including relative hindlimblength (a common intraspecific correlateof sprint speed in other lizards). We sug-gest that the longer legs of males may com-pensate for the slowing effect of their rela-tively much larger heads. In a subset ofadult males for which both field and labo-ratory data were available, sprint speedwas a better predictor of territory size andnumber of female home ranges over-lapped than was body size or any othermorphological variable. These results aresuggestive of sexual selection for whole-animal locomotor performance in male

collared lizards, but do not reveal proxi-mate correlates of performance variation.

17.1 PFENNIG, D. W.*, HARCOMBE, W. R.,PFENNIG, K. S., University of North Caro-lina, Chapel Hill, University of North Caro-lina, Chapel Hill, University of Texas, Austin.Coral snake mimics are protected only whenthey occur with their model.

Many species avoid being eaten by mim-icking unpalatable species. A critical, butuntested, prediction of mimicry theory is thatprotection from predators should break downin the absence of a dangerous model. Weevaluated this prediction in two presumedcoral snake mimicry complexes. We foundthat free-ranging predators avoidedplasticine replicas of coral snake “mimics”in areas where highly venomous coralsnakes occurred, but not in areas wherecoral snakes were absent. These data sup-port the central prediction of Batesian mim-icry and indicate that tricolor patterns innonvenonmous snakes are maintainedevolutionarily by the protection received fromresembling coral snakes.

30.1 PFENNIG, K.S.*, TINSLEY, R.C., Uni-versity of Texas, Austin, University of Bristol,UK. Parasites, female mating behavior andsexual selection on male traits.

Female choice for parasite-free matesoften may favor the evolution of elaboratemale traits that indicate male health. Yet,parasite infection of females can alter theirmate preferences, thereby mitigating selec-tion on male traits. Here, we show that fe-male spadefoot toads face a paradox.Whereas males that can provide femaleswith enhanced fertilization success are morelikely to harbor sexually-transmittable para-sites, unparasitized males may be less ableto fertilize an entire femaleís clutch. Wefound that female mate preferences de-pended on the femaleís own infection sta-tus. In particular, unpara-sitized females pre-ferred mates that potentially provide greaterfertilization success despite the risk that fe-males accrue of selecting parasitized mates.By contrast, parasitized females avoidedparasitized mates, even though such malesmay provide enhanced fertilization success.Consequently, the different preferences be-

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tween parasitized and unparasitized femalesreduce directional selection for exaggeratedmale traits. Our results suggest that to un-derstand the effects of parasites on the evo-lution of mate choice behavior, it is neces-sary to evaluate how female mate selectionis altered when females themselves are in-fected.

P3.78PFISTERMUELLER, R.*, TYLER, S.,University of Maine, Orono. Actin-rich sen-sory receptors in Convoluta pulchra(Platyhelminthes, Acoelomorpha) identifiedby correlative electron and fluorescence mi-croscopy.

Phalloidin-stained whole mounts of acoelturbellarians show brightly fluorescing club-shaped structures distributed over the epi-dermis and concentrated especially at theanterior and posterior tips of the body. Bycorrelating electron micrographic imagesand fluorescence images of Convolutapulchra, these structures can be seen to besensory receptors with a central cilium sur-rounded by a collar of microvilli. Other can-didates for the fluorescence in the epider-mis, namely gland necks and a second typeof sensory receptor lacking the collar of mi-crovilli, can be ruled out. The collared sen-sory receptors were inserted between epi-dermal cells, and each bore a central ciliumsurrounded by a collar of 6‚18 microvilli andan additional centrally positioned 2‚7 mi-crovilli of which 2 or 3 were associated witha modified rootlet called the swallow’s nest.Confocal scanning laser microscopy re-solved the core of actin filaments within themicrovilli of the collar and their rootlet-likeconnections to the base of the sensory cell.Such receptors could be identified by fluo-rescence microscopy in several other spe-cies of acoel turbellarians as well.

62.5 PHILLIPS, N.E., University of Califor-nia, Santa Barbara. The effects of larval nu-tritional history on larval condition and post-settlement juvenile growth of the musselMytilus galloprovincialis.

For organisms with planktonic feedinglarvae, variation in food availability duringthe larval stage influences the condition oflarvae as they develop, and may also have

effects on the performance of juveniles afterthey settle. To investigate this issue for themussel Mytilus galloprovincialis, full siblinglarvae were raised in the laboratory in threedifferent food treatments. Each treatment wascomposed of equal amounts of two speciesof cultured phytoplankton, and differed onlyin the total amount of food available. Thefood treatments were 20,000, 2,000, and 500cells/ml. Larval size, measured weekly, var-ied predictably with larval food treatment (i.e.larvae from the highest food level were al-ways largest). After 3-4 weeks, larvae werecompetent and settled onto introduced sub-strates. The mean size and lipid content ofsettlers was largest for larvae from the 20,000cells/ml treatment. A subset of substratesfrom each larval food treatment were kept inthe lab and half fed a high and half fed a lowjuvenile food ration for 10 and 20 days. Theremaining substrates were moved to ropeshanging from a pier and left for two weeks.Juveniles were then recovered and mea-sured. In all cases, juveniles from the high-est larval food treatment were significantlylarger than those from the lowest larval foodtreatment. From the pier, high larval food ju-veniles were 43% larger than low larval foodjuveniles even though they had been grow-ing in the same environment for two weekspost-settlement. Juvenile growth comparedbetween laboratory and field settlers fromeach of the different larval food treatmentshad substantial interactions. This work dem-onstrates the important effects larval nutri-tional history may have on juvenile perfor-mance, and how those effects might varywith conditions at the site of settlement.

P1.52PIERMARINI, P.M.*, CHOE, K.P.,EVANS, D.H., University of Florida, Dept. ofZoology. Morphological and immunochemi-cal properties of the urinary bladder in fe-male atlantic stingrays (Dasyatis sabina).

In vertebrates, urinary bladders serve astemporary storage organs for urine producedby the kidneys. Additionally, bladders areable to attenuate the final pH and ionic con-centrations of urine before it is excreted. Inelasmobranch fishes, the urinary bladder hasbeen described in the little skate (Rajaerinacea), where it is only found in females

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and has been implicated in the acidificationof urine. The goal of this study was to de-scribe the urinary bladder of another elas-mobranch species, the Atlantic stingray(Dasyatis sabina), and determine if the blad-der demonstrates immunochemical evi-dence of enzymes known to be importantfor acid/base and ion regulation. We foundthat female Atlantic stingrays have two blad-ders (one for each kidney) that accumulateurine from several collecting ducts. Histo-logical observations revealed that the blad-der is composed of an outer connective tis-sue/muscular layer and an inner cuboidalepithelium (urothelium) that lines the blad-der lumen. The urothelium is immunoreac-tive for carbonic anhydrase, vacuolar-pro-ton-ATPase, and Na+,K+-ATPase, suggest-ing that it may have a role in acid/base andion regulation of the Atlantic stingray. Sup-ported by EPA STAR Grant U-915419-01-0(PMP), Sigma-Xi Grants-in-Aid of Research(KPC), and NSF Grant IBN-9604824 (DHE).

33.3 PIERMARINI, P.M.*, EVANS, D.H.,University of Florida, Dept. of Zoology. Effectof salinity on expression of the vacuolar pro-ton-ATPase B-subunit in the gills of a eury-haline stingray (Dasyatis sabina).

The vacuolar proton-ATPase (V-H-AT-Pase) is an important ion transporter that isresponsible for energizing a variety of ac-tive transport processes in animals. Recently,the V-H-ATPase has been consideredalikely transporter for driving active sodiumuptake by the gills of freshwater teleosts. Inaddition, it has been demonstrated that theactivity and expression of V-H-ATPase in thegills decreased when freshwater rainbowtrout (Oncorhynchus mykiss), were accli-mated to seawater. To date, V-H-ATPase hasbeen immunolocalized in the gills of a ma-rine elasmobranch (Squalus acanthias), butstudies on its expression in response tochanges in environmental salinity have yetto be conducted. In this study, we used im-munochemical techniques to examine theeffect of environmental salinity on expres-sion of the V-H-ATPase B-subunit in a eury-haline elasmobranch, the Atlantic stingray(Dasyatis sabina). Western blots demon-strated that V-H-ATPase expression was

negatively correlated with environmental sa-linity; gills from freshwater rays demonstratedthe highest abundance of the transporter,while lowest abundance was associatedwith gills from seawater rays. Immunohis-tochemistry revealed that V-H-ATPase-richcells were present on both the gill lamellaeand interlamellar region of freshwater rays,while seawater rays only had V-H-ATPase-rich cells on the gill interlamellar region. Ourresults demonstrate that branchial V-H-AT-Pase expression in the Atlantic stingray fol-lows a similar trend as found in the rainbowtrout, and we suggest that the V-H-ATPasein elasmobranch gills may be important forion uptake from freshwater environments.Supported by EPA STAR Grant U-915419-01-0 (PMP) and NSF Grant IBN-9604824(DHE).

S15.3PIERSMA, T.*, VAN GILS, J.,DEKINGA, A., SPAANS, B., DIETZ, M.W.,VISSER, G.H., NIOZ, Texel and University ofGroningen, NIOZ, Texel and University ofGroningen, NIOZ, Texel, NIOZ, Texel, Uni-versity of Groningen, University of Groningen.Physiology-based trade-offs in diet and habi-tat selection of a small shorebird.

Red knots (Calidris canutus, Scolo-pacidae) are small, 120 g, shorebirds thatbreed on High Arctic tundra and spend thenonbreed-ing season in coastal intertidalareas, reaching much of the world’s coast-lines in the course of their migrations. Redknots are sensory equipped to efficientlydetect hard-shelled prey such as bivalvesburied in soft sediments. They are also spe-cialized in processing these prey that con-sist largely of salt water and shell. We havestudied their diet and habitat requirementin the field and in the laboratory using alarge array of techniques, often focussingon what we consider key physiological pro-cesses. Using energy budgets as the ba-sis, we aim to contrast the great range ofenergy expenditure levels encountered byindividual knots in the course of their an-nual cycle and by knots of different popu-lations spending the nonwintering seasonin very different climates. Shifting focus tothe components of energy budgets, weexamine the different cost factors and the

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extent to which birds try to minimize thesecosts, and the gain functions of differentkinds of prey and whether the birds try tomaximize these gains. Underlying theseconsiderations is the realization that thephenotypic flexibility of red knots and othershorebirds demands that external (envi-ronmental) and internal (physiological)factors always have to be studied in con-cert.

P2.43PIRTLE, T.J.*, SATTERLIE, R.A., Ari-zona State University. Ionic currents under-lying the activity of swim interneurons ofClione limacina.

The marine pteropod mollusk, Clionelimacina is used as a model system to studythe cellular basis of locomotor speed change.Clione swim by alternate dorsal and ventralflexion of wing-like parapodia. The swim cen-tral pattern generator is located in the pedalganglia and consists of two groups of inter-neurons — one group of interneuron (d-in-terneurons) controls the dorsal bend of thewing and another group (v-interneurons)controls the ventral bend of the wing. Thetwo antagonistic groups of interneurons in-teract through reciprocal inhibitory synapses.Thus, when one group of interneuron is ac-tive it simultaneously inhibits activity in theother group. Additionally, both d-interneu-rons and v-interneurons exhibit postin-hibitory rebound (PIR). Jointly, the recipro-cal inhibitory synaptic connections betweend-interneurons and v-interneurons and PIRgenerate the basic motor rhythm. Here wedescribe preliminary data that suggests thatisolated Clione swim interneurons exhibitthree inward currents that include an inwardcurrent that generates PIR (IPIR). In addition,Clione swim interneurons exhibit at least twooutward currents — one that closely re-sembles a delayed rectifier type K+-current(IK) and one that closely resembles the fasttransitory K+-current (IA). Changes in swim-ming speed are produced in part byserotonin’s modulation of the intrinsic prop-erties of swim interneurons. We are currentlyinvestigating serotonin’s modulation of iden-tified currents in Clione swim interneurons.

46.5 PIZER, M.*, WRAY, G.A., Duke Univer-sity. The evolution and development of left-right asymmetry in echinoderms.

Echinoderms have a bilaterally symmetri-cal larva that becomes left-right asymmetricwhen adult structures begin to develop.These structures form primarily on the leftside of the larva, eventually producing apentaradially symmetrical adult. This un-usual symmetry transition is one of the mostdistinctive characteristics of the phylum andplays a central role in many theories of echi-noderm origins. We are using a variety ofapproaches to investigate the evolution anddevelopment of left-right asymmetry andmetamorphosis in echinoderms. The first ofthese approaches involves determining thefates of cells in the left and right larval coelo-mic sacs in a variety of echinoderm groups.Comparison of the degree of left-right asym-metry between different classes of echino-derms suggests how this feature hasevolved within the phylum. The second ap-proach uses molecular developmental tech-niques to investigate the mechanistic basisof left-right asymmetry in echinoids. Thestudy of the developmental mechanisms ofthe unique symmetry characteristics ofechinoderms has important implications forthe evolution of these features in echino-derms and in deuterostomes.

P3.99PLACE, S.P.*, HOFMANN, G.E., Ari-zona State University. Temperature-proteininteractions of the molecular chaperoneHsc70 purified from a eurythermal goby.

Many heat shock proteins (Hsps) areknown molecular chaperones that are fun-damental to protein folding. Although a greatdeal is known about Hsps as molecular chap-erones in model systems (e.g., E. coli andcultured mammalian cells), very little isknown about their function in organisms fromnatural populations. Consequently, we havelittle insight into the temperature interactionsof Hsps under ecologically relevant condi-tions. In this study we examined the tem-perature-protein interactions of a molecularchaperone, Hsc70, from Gillichthys mirabilis,a goby that encounters a broad range of tem-peratures in its estuarine habitat. Seasonaltemperatures experienced by this fish range

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from 7 - 37ƒ C annually. Our goal was toaddress the question of how the biochemi-cal function of Hsc70 mapped onto the rangeof temperatures encountered by G. mirabilisin its natural environment. For these stud-ies, we examined the activity and biochemi-cal properties of Hsc70 purified from whitemuscle of G. mirabilis. Since Hsc70 bindsand hydrolyzes ATP during a chaperoningcycle, ATPase activity was used as an indi-cator of chaperone function. Using an invitro 32P-based ATPase assay, the resultsshowed that (1) Hsc70 has a generally lowintrinsic ATPase activity that can be stimu-lated by the addition of an unfolded protein,(2) Q10 calculations for the chaperone rangefrom 1.2 -2.2 over the environmental tem-perature range for G. mirabilis, and (3) thethermal stability of Hsc70 greatly exceedsenvironmental temperatures for this species.The results indicate that Hsc70 from G.mirabilis is a thermally stable protein withan ATPase activity that is functional over abroad range of environmentally relevanttemperatures.

S2.8 PODLASEK, C.A., Northwestern Uni-versity Medical School. Posterior Hox geneexpression in developing genitalia.

The process of development requirescomplex interactions of mesenchyme andepithelium to specify tissue identity andunique organ specific morphology. The Hoxfamily of homeobox genes encode transcrip-tional regulators that are crucial for specifi-cation of positional identity during embryo-genesis and which are expressed in a colin-ear manner in regionalized domains alongthe main body axis, limb, lung, and gut. Con-served mechanisms of gene expression andregulation are apparent during embryogen-esis and postnatal morphogenesis of theseorgan systems, with minimal variation evi-dent across species. A rudimentary path-way of essential developmental genes hasbeen defined in the limb, which includes bothpositive and negative growth regulators suchas Hox genes, Sonic hedgehog (Shh), andBone morphogenetic proteins 2 and 4.These same genes are abundantly ex-pressed in the primary and accessory sexorgans during development and targeted

loss of a specific member of the pathwayresults in genital abnormalities. It is proposedthat vertebrate genitalia represent anotherdevelopmental axis, similar to the limb, andthat mechanisms that define positional iden-tity and control proliferation in the limb, lungand gut are also crucial for normal specifi-cation and morphogenesis of the primaryand accessory sex organs.

62.6 PODOLSKY, R.D., University of NorthCarolina, Chapel Hill. Intertidal embryos:temperature tradeoffs during early develop-ment.

Species from several phyla brood or de-posit benthic embryo masses in intertidalhabitats. These habitats can expose embryosto extreme environmental change on shorttime-scales, which can have diverse effectson development. In the molluscMelanochlamys diomedia environmental (=developmental) temperature can changefrom 11 to 34-degrees C and back over atidal exchange. In the laboratory, time tohatching was influenced by temperature re-gimes associated with large vs. small ex-changes, and with variable vs. constant tem-peratures. Although embryos developedfastest under a regime characteristic of alarge exchange, they are also the most vul-nerable to heat stress during such periodsin the field. Embryos are especially vulner-able during their first one or two low tideswhen the induction of heat shock protein ex-pression is minimal or absent. In addition,embryo masses face a threat of prematuredislodgment from the substrate, which maybe greater during periods of greater ex-change, or may be reduced overall by morerapid development. These results indicate acomplex set of tradeoffs that influence thesuccess of development under variable tidalconditions.

S8.2 POLCYN, D.M., California State Uni-versity, San Bernardino. From creepycrawlies to cuddly critters: can arthropodsreally be tweaked enough to capture thenation’s attention?

In a nation which spends billions of dol-lars a year to kill arthropods, in which peopleyoung and old would rather swat an insectthan observe it, it seems hard to imagine

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how film studios could create a cast of insectcharacters realistic enough to retain their bio-logical characteristics yet “cuddly” enoughto garner the affection of a mammal-orientedpublic. The solution, evidenced in severalrecent arthropod-based family films, hasbeen an interesting blending of the odditiesof arthropod natural history and anatomy withfamiliar, and often comforting, mammalian(usually human) characteristics. Although theresulting characters and story lines are notcompletely biologically realistic, they serveto introduce and educate the public to thelargest group of organisms on earth -theArthropods. Story lines revolve around thedynamics of social insect societies, interspe-cific and intraspecific competitive interac-tions, predator-prey relations, and the vari-ous ecological roles played by different spe-cies. The tremendous variety of anatomicalmodifications seen in the arthropods facili-tates the development of both “good” and“evil” characters, and the presence of char-acteristics such as the exoskeleton andhinged joints has been exploited in the de-velopment of animated characters as wellas action figures and other toys. Appropri-ate terminology, although kept to a minimum,is used throughout the films to a surprisinglysuccessful degree. Viewed as a whole, therecent releases of arthropod-based anima-tions have been far more realistic in portray-ing the structure, function and dynamics ofarthropods than had previous attempts, andas such serve to simultaneously entertainand educate a national audience possess-ing an abysmally low level of scientific lit-eracy.

41.4 PORTER, H.T.*, MOTTA, P.J., Univer-sity of South Florida. A comparison of preycapture behavior and kinematics in threeram feeding fishes.

Ram feeding is the process by which apredatory fish uses a high-velocity lunge orchase to overtake its prey. This study com-pares the strike and prey capture behaviorsand kinematics of three species of ram-feed-ing fishes: Florida gar Lepisosteusplatyrhincus, redfin needlefish Strongyluranotata, and great barracuda Sphyraena bar-racuda. These ram-feeding piscivores are

morphologically similar with fusiform bod-ies, posteriorly-placed dorsal and anal fins,and large, conical teeth. Strike and prey cap-ture behaviors and kinematics for five indi-viduals of each species were recorded withhigh-speed video. Pre-strike behavior in garconsists of a slow stalk, resulting in the close,lateral positioning of the predator’s head rela-tive to the prey. Gar employ a sideways lungeof the head during the strike, which lasts only25 to 40 milliseconds. Needlefish and bar-racuda exhibit longitudinal orientation to theprey before the strike, followed by a highvelocity, head-on lunge initiated by an s-start.Needlefish and barracuda achieve averagestrike velocities of 64 cm/s and 144 cm/s re-spectively. Prey capture in gar and needle-fish is characterized by the jaws closing onthe prey, which is generally positioned or-thogonal to the jaws. This is followed bymanipulation to reposition the prey head first,and suction transport into the buccal cavity.Manipulation can last up to 7000 millisec-onds. Prey capture in barracuda is accom-plished by closing the jaws after the preyhas entered the buccal cavity, resulting inram transport of the prey with no oral ma-nipulation. The differences among thesespecies in kinematics may be related to dif-ferences in cranial morphology, size, andhabitat-specific behaviors.

S5.2 PORTER, W.* P., BUDARAJU, S.,STEWART, W.E., RAMANKUTTY, N., Univer-sity of Wisconsin, Madison. Physiology on alandscape scale: applications in ecologicaltheory and conservation practice.

Plant properties play a crucial role in anovel and unsuspected way that involvesthe physiology of animals as does effects ofclimate variation in time and space in howmany species can coexist in the community.This paper describes how climate variationin time and space can constrain communitystructure on a global scale. We explore bodysize scaling and the energetic consequencesin terms of absorbed mass and energy andexpended mass and energy. We explainhow morphology, specific physiological prop-erties, and temperature dependent behav-iors are key variables that link individualenergetics to population dynamics and com-

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munity structure. For mammals ranging insize from mice to elephants we show thatcalculated metabolic costs are in agreementwith experimental data. We also demonstratehow we can do the same for birds ranging insize from hummingbirds to ostriches. Weshow the impact of changing posture andchanging air temperatures on energeticcosts for birds and mammals. We demon-strate how optimalbody size that maximizesthe potential for growth and reproductionchanges with changing climatic conditionsand with diet quality. Climate and diet mayplay important roles in constraining commu-nity structure (collection of functional typesof different body sizes) at local and globalscales. Thus, multiple functional types maycoexist in a locality in part because of thetemporal and spatial variation in climate andseasonal food variation. We illustrate howthe models can be applied in a conserva-tion and biodiversity context to a rare andendangered species of parrot, the Orange-bellied Parrot of Australia and Tasmania.

19.1 POWELL, J.S.*, RAFFA, K.F., Univer-sity of Wisconsin, Madison. The effect of feed-ing specificity on the fate of terpenoids inLymantriidae (Lepidoptera).

Insect herbivores possess a wide arrayof mechanisms for processing ingestedphytochemicals. However, it is difficult topredict the fate of phytochemicals since it isinfluenced by many factors. We are testingwhether feeding specificity influences therelative extent to which an herbivore relieson excretion, sequestration, and metabolism.Our model consists of 5 generalist and spe-cialist Lymantriids, each of which includeconifer terpenes within its diet. The monoter-penes bornyl acetate, limonene, andmyrcene, and the diterpenes isopimaric acidand neoabietic acid all occur in tamarack, acommon coniferous host of the 5 Lymantriidspecies. Each species is fed knownamounts of these compounds in amendeddiet. Frass, larvae and exuviae are analyzedto quantify excretion and sequestration. En-zyme inhibitors are used to determinewhether specific enzymes are responsiblefor metabolism. The fate of monoterpeneshas been examined in 4 species. Prelimi-

nary results suggest metabolism is the mostimportant mechanism for processing monot-erpenes. Limonene and myrcene appear tobe completely metabolized. Borneol, a me-tabolite of bornyl acetate is recovered infrass, larvae, and exuviae. Piperonyl butox-ide does not affect recovery of any monoter-pene or performance of larvae, indicatingP450 enzymes are not responsible for me-tabolizing these monoterpenes. Excretionappears to be partially involved in process-ing bornyl acetate, but not limonene ormyrcene. Both bornyl acetate and borneolare recovered from frass. The extent of eachmechanism in processing monoterpenesdepends on both the larval stadium and ter-pene concentration.

59.5 POWELL, K.P.*, ROMMEL, S.A., FLMar. Res. Inst., St. Petersburg, FL. Reproduc-tive anatomy of the female Florida manatee(Trichechus manatus latirostris).

The Florida manatee (Trichechusmanatus latirostris), an endangered marinemammal, inhabits coastal waters of theSoutheastern United States. Relative tomany other mammals, descriptions of thefemale reproductive tract of the Florida mana-tee are limited. It is essential to understandthe reproductive capabilities and limitationsof this species in order to better assess itsreproductive potential. In this study, repro-ductive tracts from over 100 female Floridamanatee carcasses, from calf to adult, wereexamined. Gross anatomical descriptionswere made, refining previous descriptionsof the reproductive tract; we compare themanatee with dogs, elephants and dugongs.The manatee tract resembles that of theclosely related dugong. The perianal posi-tion of the urogenital opening (on the ven-tral abdomen) is the only reliable sexuallydimorphic external feature. The urogenitalsinus is moderate in size, in contrast to dogsand elephants. A distinct hymen is presentin very young manatees. The cervical canalin manatees is directed cranioventral vscraniodorsal in dogs. Cervical position im-plies sperm deposition is vaginal. The uterusis bicornuate. The distal horns are perpen-dicular to the uterine body, in contrast to theY shaped uterus in dogs and elephants. The

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ovaries are unusual in size, shape and po-sition. In mature individuals maximum lineardimensions can range from 12 to 8 cm. Theshape is typically flattened and irregular inoutline. They are located in hypogastric fos-sae between the last two ribs, distant fromthe kidneys. Each ovary of reproductively ac-tive manatees may have numerous enlargedfollicles though only a single egg may bereleased.

9.4 POWELL, M.L.*, WATTS, S.A., Univer-sity of Alabama at Birmingham. Survivor: theenergetics of crayfish in burrows.

Procambarus clarkii (PC) and P.zonangulus (PZ) share overlapping rangesin the southeastern United States. Within thisshared range the success of each speciesvaries, possibly related to the ability to sur-vive environmental challenges and ex-tended periods of nutrient deprivation dur-ing the summer when both species retreatto burrows. Metabolic rate, proximate com-position and energy content were deter-mined for adult male crayfish during a five-month starvation period. The pattern andsource of nutrients utilized during starvationvaried between species. In PZ 75 % of thetail muscle and 30 % of the hepatopancreaswas mobilized during the starvation period,compared to 60 % of both the tail muscleand hepatopancreas in PC. Although agreater percentage of the dry tissue was mo-bilized from the tail and hepatopancreas ofboth species, over 50 % of the total dry ma-terial was mobilized from the remaining car-cass. Nutrient utilization in both species wastissue-specific; the hepatopancreas mobi-lized a greater percentage of lipid, and tailmuscle a greater percentage of protein. PCmobilized almost twice as much energy asPZ, but from different tissues. PC mobilized8 % of the energy from the hepatopancreas,14 % from the tail and 78 % from the car-cass. PZ mobilized 14 % of the energy fromthe hepatopancreas, 59 % from the tail andonly 27 % from the carcass. Survivorship was45 % for PC and 71 % of PZ. These differentresponses to nutrient deprivation may par-tially explain the observed changes in spe-cies composition in ponds.

P1.54A POWERS, D.R.*, ANDREW-JESKI,P.M., GRAMENZ, P.W., KIMBERLY, D.J.,George Fox University, Newberg, OR 97132.Cutaneous water abosorption by Rough-skinned newts (Taricha granulosa) in openterrain vs. water-soaked environments.

We measured cutaneous water uptakerate in Rough-skinned Newts (Taricha granu-losa) using an open terrestrial (ventral sur-face only) and submergence (whole body)model to evaluate their ability to regulate wa-ter balance in open terrain vs. water-soakedenvironments. These are meaningful mea-surements for this species because theyhave both an aquatic and terrestrial phaseduring their annual cycle, and the osmoregu-latory challenges of these two periods aredramatically different. We hypothesized thatnet water flux rate (absorption rate – evapo-ration) would be higher in the submergencemodel based on two factors. First, this spe-cies is aquatic for much of the year and islikely adapted primarily to this environment.Second, using immunohistochemistry wehave shown that the outer skin cells of boththe dorsal and ventral surfaces of the newtcontain high densities of aquaporin (AQP)water channels. This indicates that thesesurfaces are probably actively involved inwater absorption. Surprisingly, our measure-ments show that net water flux rate in theopen terrestrial model is slightly higher thanin the submergence model. While the rea-sons for this result have yet to be determined,it is possible that ventral skin permeability isincreased at appropriate times to maximizeabsorption rate. One way to control skin per-meability to water is to regulate the numberof active AQP water channels. Hormonessuch as ADH, AVT, and AII will likely be ma-jor players in the regulation of skin perme-ability regardless of the role of AQP. Previ-ous studies have shown that some AQP wa-ter channels are responsive ADH. We arecurrently working to sequence the AQP innewt skin so it can be compared to thosethat have shown ADH sensitivity.

S11.14 PRATT, G., MIT, Cambridge. Lowimpedance robotics.

Almost all robots, including current walk-ing robots, embody a “stiffer is better” de-sign and control philosophy inherited from

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the earliest days of numerically controlledmachine tools, where position accuracy inthe face of unpredictable force disturbanceswas of paramount importance. This philoso-phy is so pervasive that is has become partof the cultural definition of a robot. By con-trast, the impedance of animals is low. Wecannot hold positions accurately in the faceof unexpected force disturbances. What wecan do is execute natural tasks, like locomo-tion, manipulation and prey catching, withbreathtaking agility and grace. Previous workhas shown that the passive dynamics of ananimal’s body acts to self-stabilize and au-tomatically sequence some movements. Un-fortunately, in today’s stiff, trajectory con-trolled robots, such natural dynamics areover-ridden. We have developed a family oflow-impedance actuators, mechanisms, andcontrol philosophies that allow our robots tointeract with the world more softly - more likeanimals. In the actuator arena, we have de-veloped a succession of series elastic ac-tuators that incorporate elasticity betweenthe motor/transmission and the load. Usedin a feedback configuration, this elasticitygives our actuators low minimum imped-ance, high force fidelity, high dynamic range,high shock tolerance, and the capacity forenergy storage. In the control arena, we havedeveloped physics-based low-impedancetechniques and a general programming toolcalled virtual model control that extends theimpedance control paradigm of robot con-trol. Using these control methods on bothsimulated and real low-impedance walkingrobots, we have demonstrated that soft,model free control can be effected in paral-lel with the natural dynamics of the robot.Experiments have shown that these tech-niques are capable of achieving both stabil-ity, performance, and, to the human eye,grace.

25.4 PRATT, M.C., Duke University,Durham NC. Growth and survival of an erectand encrusting bryozoan in different flowhabitats.

Bryozoans are active filter feeding inver-tebrates that can exhibit a wide variety ofdifferent colonial growth forms. These growthforms can roughly be divided into speciesthat are erect or encrusting. I compared the

effects of hydrodynamics on the growth andsurvival of an encrusting and an erect bryo-zoan. Membranipora membranacea has anencrusting growth form and is found almostexclusively on large flat macroalgae (suchas kelps) in relatively high and low flow habi-tats. Bugula pacifica has an erect growth formand is generally found on hard substrata(such as docks or rocks) in relatively lowflow habitats. These two species do occa-sionally overlap in habitat: both can be foundon large macroalgae in low flow environ-ments. Previous data suggest thatMembranipora can capture more particlesthan Bugula at both slow (2.5cm/s) and fast(10cm/s) flow velocities. However, it remainsto be seen whether a higher particle capturesuccess translates into faster growth and/orhigher survival rates. I measured the growth(change in area) and survival rate ofMembranipora and Bugula colonies in thefield in a high and low flow habitat over amonth and a half time period. Growth ratedid not vary greatly between high and lowflow habitats for either species, but survivalrate did vary between species and betweenhabitats. Membranipora had a higher sur-vival rate than Bugula in both flow habitats,and both species had a higher survival ratein the slower flow habitat than in the higherflow habitat. These results suggest that hy-drodynamics can have a large effect on sur-vival of bryozoans based on their growthform.

P1.53PREEST, M.*, GONZALEZ, R., TheClaremont Colleges, University of San Di-ego. Ion balance in the extremely acid-toler-ant neon tetra.

Neon tetras (Paracheirodon innesi) arenative to acidic waters of the Amazon. Theyare highly acid-tolerant and survive expo-sure to acidity levels that are lethal to manyspecies due to a disruption of ion fluxes,particularly Na+. Uptake of Na+ in neon tet-ras is insensitive to pH (down to 3.25), andinflux is only mildly sensitive to amiloride, aNa+ channel blocker. This suggests Na+ up-take might occur as the result of a novelmechanism. We investigated ion balance inneon tetras by measuring ion fluxes duringexposure to a variety of blockers of trans-porters proposed to exist in gill epithelia. To

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assess the effectiveness of the blockers, wealso measured fluxes in goldfish (Carassiusauratus, a non-acid tolerant species). Na+/H+ exchange blockers (DMA, MIA, EIPA,HMA) and Na+ channel blockers (benzamil,phenamil) failed to inhibit Na+ uptake in neontetras, but all, except benzamil, reduced up-take in goldfish. The H+ blocker vanadatehad no effect on either species. A Na+/Cl- co-transport blocker, furosemide, inhibited Na+

and Cl- uptake in goldfish, but not neon tet-ras. Exposure to AgCl2, a potent Na+/K+ AT-Pase blocker, reduced uptake in both spe-cies. Finally, acetazolamide, an inhibitor ofcarbonic anhydrase did not inhibit Na+ up-take in either species, but reduced Cl- up-take in neon tetras. The relative insensitivityof neon tetras to this array of agents may bedue to a novel mechanism for branchial Na+

uptake. Alternatively, if they possess thesame mechanisms, the transporters are suf-ficiently distinct so that inhibitors effectiveagainst other fish have no effect on neontetras. These differences may be responsiblefor continued function at extremely low pH.

P1.78PRESSMAN, E.*, TEMPLE, J. G., MaryWashington College, Fredericksburg, VA. Anexamination of the thermoregulatory re-sponse of the garter snake Thamnophis ra-dix radix to the bacterium Aeromonashydrophila.

Research has shown that certain spe-cies of ectotherms behaviorally induce a fe-ver in response to an infection. Researchhas also shown that the garter snakeThamnophis sirtalis shows a hypothermicresponse to bacterial infection. This prelimi-nary experiment addresses the thermoregu-latory behavior of Thamnophis radix radix inresponse to a bacterial (Aeromonashydrophila) infection. It also addresseswhether, if given a localized infection,Thamnophis radix radix will induce a feveronly in the infected part of its body by com-paring the thermoregulatory responses ofsnakes given localized infections to thosegiven a general infection. Snakes were al-lowed to thermoregulate in an aquarium witha thermal gradient. For the general infectionprocedure, saline was injected intraperito-neally and 48 hours later, alcohol-killedAeromonas hydrophila were injected intra-

peritoneally. For the localized infection, thesame injection schedule was followed, onlyinjections were subcutaneous. Following allinjections, cloacal temperatures were mea-sured continuously. The position of eachsnake on the gradient was recorded to de-termine patterns of thermoregulation. Notemperature change was significant, thusshowing neither a hypothermic nor a hyper-thermic response to infection. Thermoregu-latory patterns did not vary between the re-sponses to saline and bacteria injections orbetween responses to subcutaneous andintraperitoneal injections.

P1.15PRESTON, R.L.*, PRES-TON, E.J.D.,MIDDAUGH, D.R., Illinois State UniversityEnzymatic racemization of amino acids inmarine invertebrate tissues.

Previously we showed that D-amino ac-ids are present in the cellular free aminoacid pools of diverse groups of marine in-vertebrates. Using a coupled enzyme assayemploying D-amino acid oxidase or chiralHPLC, we surveyed over 130 species ofmarine invertebrates in 12 phyla. About 40%of these species in 10 phyla showed detect-able levels of D-amino acids. In some cases,very high concentrations were observed, e.g.gill tissue of the soft-shelled clam, Myaarenaria, contained 63 mM D-alanine. D-Aspartate, D-glutamate, D-serine and D-ala-nine were detected in other species. We alsoshowed that 14C-D-alanine was absorbedvia membrane transport processes and me-tabolized. Transport occurred via low affinityL-amino acid preferring pathways or by D-stereoselective transport systems. The ma-jor pathway for D-alanine metabolism in-volved racemization. Using a modificationof the coupled enzyme assay and chiralHPLC, we detected alanine racemase ac-tivity in 15 species of marine invertebrate (5phyla). Analysis of partially purified race-mase from Mya gill revealed this enzymewas relatively specific for alanine (Km 9 mM).We screened other species for alanine andserine racemase activity. Some species ex-pressed only serine racemase activity (e.g.Limulus polyphemus) or only alanine race-mase activity (e.g. Lunatia heros). Other spe-cies expressed both serine and alanine race-mase activity (e.g. Asterias forbesi). We cur-

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rently are purifying alanine racemase fromMya and have tentatively identified the ala-nine racemase gene. These data support thehypothesis that D-amino acids have signifi-cant biological roles in marine invertebratetissues. Accumulating evidence suggeststhat D-amino acids may function asneuromodu-lators, as precursors for endog-enous antibiotics, may have a role in osmo-regulation and provide a contribution to thenutrition of marine invertebrates.

36.4 PRETE, F.R.*, HURD, L.E., JONES, T.,PORTMAN, R., SINGH, T.B., CO, J.E., VisionTech, inc., Morton Grove Il, Washington &Lee University, Lexington, VA, Virginia Mili-tary Institute, Lexington, VA, University ofTulsa, OK, Washington & Lee University,Lexington, VA, Virginia Military Institute, Lex-ington, VA. Scent of a woman: the first identi-fication and assay of a mantid pheromone.

Although insect pheromones are wellstudied, little is known about their roles inthe life of predators such as praying man-tids. We examined the mantis Sphodromantislineola, to determine (1) if females producea pheromone-like chemical, (2) if the chemi-cal has an effect on male behavior, and (3) ifmales possess antenna sensilla capable ofsensing a pheromone. Female headspacesamples collected via solid phasemicroextrac-tion and analyzed with gas chro-matography revealed a 1:3 ratio oftetradecanal to pentadecanal (the putativepheromone). In Y-maze tests, males alwayschose the maze arm with the synthesizedpheromone, spending an average of 99%their time there. In an open-field test, the syn-thesized pheromone elicited vigorous mat-ing-related behaviors directed toward othermales and dummies. These behaviors in-cluded flying leaps onto males, abdominaltwisting and lateral flexion (indicative of at-tempts to intromit), and phallomere spread-ing. SEM photos of male antennae revealedthat among the estimated 30,000 hair- andpeg-like sensilla were several well-recog-nized classes of chemoreceptors: large (100-130 um long) uniporous trichoid sensilla withunelaborated apical pores; small (<100 umlong) multiporous trichoid sensilla; grooved,multiporous basiconic sensilla; and grooved,

basiconic sensilla with apical pores. Of these,the multiporous trichoid and basiconic sen-silla are the most likely to be olfactory recep-tors responsive to airborne female producedpheromones.

42.6 PRICE, C.L.*, MEYERS, J.J.,HERREL, A., NISHIKAWA, K.C., NorthernArizona University, Flagstaff, Northern Ari-zona University, Flagstaff, University ofAntwerp, Belgium, Northern Arizona Univer-sity, Flagstaff. Scaling and kinematics oftongue projection in chameleons.

Within a year from hatching, chameleonscan grow up to two orders of magnitude. Thisrapid increase in body size likely imposesconstraints on the function of chameleonmuscles used for prey capture. In this study,we looked at the possible structural andfunctional constraints of prey capture kine-matics associated with body size. Constraintson the feeding system are likely high, asunique, ballistic tongue projection requiresaccurate control of the jaw and hyolingualapparatus. Mass, SVL, jaw length and headwidth, were measured in order to identifypatterns of growth. Feeding sequences ofeach chameleon were filmed at 250 framesper second with a high-speed digital videocamera. Movement, velocity and accelera-tion of the jaw and the hyolingual apparatuswere quantified. Several species of chame-leons were studied, including C. jacksonii,C. melleri, C. oustaleti, C. fischeri and C.calyptratus, which varied in size from ap-proximately one gram to 200 grams. Ouranalysis showed that the kinematics of preycapture in chameleons scale allometricallywith body size. The data were graphedagainst mass, which yielded a linear regres-sion. The slope values were equivalent toslopes predicted by elastic similarity for al-lometric growth. Change in maximumtongue projection and maximum hyoid pro-trusion can be explained by allometricgrowth. The scaling of maximum gape dis-tance showed slight negative allometry.Analyses of EMG and muscle force mea-surements will be used to test these predic-tions further.

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67.4 PRUM, R.O.*, WILLIAM-SON, S., Uni-versity of Kansas. Models of the develop-mental determination of feather shape andpigmentation pattern.

We present the first explicit theories ofthe growth of feather shape (the outline of apennaceous vane) and the determinationof within feather pigmentation pattern. Thegrowth of feathers is simulated with a math-ematical model based on six growth param-eters: (1) absolute barb and rachis ridgegrowth rate, (2) angle of helical growth ofbarb ridges, (3) initial barb ridge number, (4)new barb ridge addition rate, (5) barb ridgediameter, and (6) the angle of barb spreadfollowing emergence from the sheath. Thegrowth model simulates a diversity of shapesthat correspond closely to real feathers, in-cluding various contour feather shapes,asymmetrical feathers, and even emargin-ate primaries. Each parameter can havesubstantial independent effects on feathershape. The parameters also have complexand redundant effects on feather shapethrough their influence on the diameter ofthe follicle, the barb ridge fusion rate, andthe internodal distance. Accurate simulationof the shape and position of feather fault barsstrongly confirms the uniform absolutegrowth rate hypothesis and the realism ofthe model. Within feather pigmentation pat-terning is simulated by activator-inhibitormodels during feather growth. Simple acti-vator inhibitor models successfully simulatemost common feather pigmentation patterns,including horizontal bars, stripes, and chev-rons. More complex patterns, such as alter-nating rows of spots, can be simulated byincluding additional parameters. The pig-mentation pattern models can simulate manyof the complex transitions in feather pattern-ing observed in complex avian plumages.Together, the two models provide numeroustestable predictions about the developmen-tal determination and evolution of feathershape and pigmentation patterning.

66.2 QUINN, N.J., University of Papua NewGuinea. Reef check - Papua New Guinea’sparticipation in a global assessment of hu-man effects on coral reefs.

Villagers in Papua New Guinea (PNG)have used coral reefs for thousands of years.

Recent human development in PNG hasaltered the use of coral reefs. Today morereefs are fished commercially, used by tour-ist divers, and impacted by coastal loggingand mining companies. While the state ofthe reefs may be known locally, there hasbeen no general assessment of the humaneffects on the coral reefs. Using Reef Checkprotocol developed by Dr. G. Hodson, stu-dents at the University of Papua New Guineahave been conducting surveys on coral reefs.To do this the students needed to be taught:1) the use of a mask and snorket, 2) scubadiving skills, and 3) marine survey skills.Twenty-five students have received PADIopen water certification. Advanced studentdivers conducted surveys of over 20 reefs.The results indicate that while human im-pact is obvious on some reefs, most of thereefs surveyed are in excellent shape with ahigh percentange live coral cover. PNG reefsare among the least disturbed reefs in theglobal Reef Check survey. Few crown ofthorns starfish were observed. There is needto develop a well-funded coral reef monitor-ing program using national biologists in as-sociation with a community based marineawareness effort. Presently, many non gov-ernment conservation organizations (NGOs)are engaged in colonial conservation activi-ties. Their adgenda is directed by a foreignmembership that fund marine biodiversitysurveys using foreign experts. These activi-ties contribute little to the development oflocal skills and technology transfer. The dis-covery of new animals by foreign scientistseffectively removes the possibility of futurediscovery by national scientists. Relation-ships between colonial NGOs and nationaltertiary education institutions need to be im-proved.

P1.7 QUINN, N.J.*, NEWELL, P., Universityof West Indies, University of South Pacific.Subsurface sea water temperatures and theyear 2000 coral bleaching event in Fijianwaters.

Analysis of three years of subsurface seawater temperatures at several sites showsincreased temperatures receeding the year2000 coral bleaching event. Hugrun auto-mated temperaure recorders were deployedat 3m at twelve sites and programed to record

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temperature hourly. Temperatures in early2000 were 1oC to oC warmer than duringprevious years. Off shore temperatures inBligh Passage in previous years rangedfrom 24oC to 28oC. However, in the periodpreceeding and during the coral bleachingevent the temperature range was 26oC to29oC. The period of coolest temperatureswas typically July to early October. Tempera-tures in Bligh Passage seldom dropped be-low 25.5oC. Although temperatures on fring-ing reefs around islands were more variablethey also exhibited a similar temperatureincrease as off shore sites. The reefs nearSuva were influenced by freshwater dis-charges from the Rewa River. Suddenchanges in temperature were correlated withlarge discharges of freshwater using a con-ductivity meter. Temperatures in the lagoonalwaters off western Vite Levu were typicallywarmer than other sites.

P2.27QUINN, V.S., HEWS, D.K.*, IndianaState University. Dermal melanin densityexplains variation in a phylogenetically la-bile color signal in Sceloporus lizards: cor-relational and experimental evidence.

We examined the production of a signal-ing trait, blue abdominal patches, in threeSceloporus lizard species. Sexes and spe-cies can differ in the occurrence of thepatches. We tested the hypothesis that bluepatches require a high density of melanin inthe dermis underlying the iridophore layer,and that the mechanism is conservedamong Sceloporus expressing the patches.Measurements of relative melanin densityusing light microscopy images of abdomi-nal skin from Sceloporus undulatusconsobrinus, S. virgatus, and S. jarrovii sup-port this hypothesis. Lizards with bluepatches (male undulatus, and male and fe-male jarrovii) have more melanin than whiteabdominal skin from lizards lacking patches(female undulatus, and male and femalevirgatus). Within the sexually dimorphicundulatus (males blue females white), mela-nin abundance in blue abdominal skin washigher than melanin in white skin of femalesremoved from the male patch location. Injarrovii (both sexes have blue abdominalpatches) and virgatus (neither sex has blue

abdominal patches), the pattern of highermelanin density in blue skin was consistentregardless of species or sex. We are quanti-fying melanin density of blue skin fromundulatus females (normally white) that wereandrogen-manipulated as hatchlings for anexperimental test of the melanin hypothesis.

30.3 QUINN, V.S.*, HEWS, D.K., IndianaState University. Species variation in femalepreference for male behavioral and morpho-logical signaling traits.

Handicap and Fisherian run-away theo-ries of sexual selection predict that male traitsand female preferences for those traits havecoevolved. Thus, gains or losses of maletraits are coincident with female preferencesfor those male traits. However, sensory biasdoes not predict this coevolutionary pattern.We examined the coevolution of males andfemales in a phylogenetic context by com-paring the responses of females to male traitsin sister species of Sceloporus lizards bymanipulating a pair of blue abdominalpatches of skin. We measured female re-sponse in S. u. consobrinus, a lizard repre-senting the ancestral and typical characterstate of sexual dimorphism. We also exam-ined S. virgatus a species representing aderived character state, male loss of abdomi-nal coloration. We presented females withpairs of male conspecifics, one with blue-painted patches and the other with white-painted patches. Female S. u. consobrinus,did not preferentially associate or copulatewith males based on abdominal coloration,but did preferentially associate with the firstmale to display. Female S. virgatus associ-ated with and were mounted by white-painted more than blue-painted males. Thesedata suggest that female responses to ab-dominal coloration have not coevolved withlosses of this male signal in these species.

S1.3 RANDALL, J.A., San Francisco StateUniversity. Why do desert rodents drum theirfeet?

Vibrational signals are one of the morecommon modes of communication in ro-dents. Striking the feet on the ground to cre-ate mechanical vibrations seems to haveevolved independently in several lineagesof fossorial and semi-fossorial desert rodents

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on all continents except Australia. Footdrum-ming produces both substrate-borne and air-borne acoustic energy in multiple contexts.In the social context, rodents footdrum tocommunicate territorial ownership, competi-tive superiority, familiarity, submission andpredation risk to conspecifics. Footdrummingis species specific and ranges from singlethumps to individually distinct footdrummingsignatures that the banner-tailed kangaroorat, Dipodomys spectabilis, uses to adver-tise its territorial ownership to neighbors.Footdrumming signatures are flexible andcan be adjusted to changes in the socialenvironment. Many desert rodents alsofootdrum in the presence of predators. Soli-tary kangaroo rats footdrum at snakes andkit foxes in individual defense to inform thepredator that the rat is alert, not easy preyand to go away. In contrast to solitary ro-dents, the great gerbil, Rhombomys opimus,from Central Asia is highly social and uses acombination of footdrum-ming and vocaliza-tions to communicate predation risk to off-spring, relatives and mates. Great gerbilsmay footdrum in the presence of snakes andpolecats that hunt in burrows to communi-cate predation risk to family members insidethe burrow. There is much more to be learnedabout vibrational communication in rodents.Research on more species from differenthabitats and lineages should reveal the di-versity and importance of this mode of com-munication in mammals.

S11.9RAYNER, J. M. V. *, MAYBURY, W. J.,COULDRICK, L. B., University of Leeds,United Kingdom, University of Bristol, UnitedKingdom, University of Leeds, United King-dom. Aerodynamic control by the avian tail.

The bird tail has been credited as ameans of controlling stability andmanoeuvrability in flight and as a supple-mentary lifting organ, but others have em-phasized its role in sexual selection and dis-play. Theoretical models of tail aerodynam-ics based on slender wing theory have nothitherto been tested. Flow visualization andforce measurements with mounted Euro-pean starling Sturnus vulgaris reveal the ge-ometry of vortices around the tail, and theeffect of the tail on airflow around the body.

Lift from the spread starling tail at low speedsis strongly influenced by the presence of thebody and does not correspond to predic-tions of slender wing theory. A furled tail hasan important effect on body aerodynamics; itacts as a splitter plate, controlling the onsetof separation on the anterior part of the body,and reducing parasite drag significantly.Flow control and body drag reduction is hy-pothesized to be the major role of the tail innormal forward flight, although the tail playsvaried roles in different species. It probablyevolved from a balancing, and heavy, bonytail in bipedal theropods.

S8.4 REDD, J., SONY Pictures Image-works. Modeling fur and feathers and theneed to balance perception, science, andentertainment.

Artistic decisions are constantly maderegarding the presentation of characters infilms, especially when fanciful characters areplaced into realistic or photorealistic envi-ronments. When animating or digitally pro-ducing a clearly fanciful character, care mustbe taken to adopt certain elements that willpersuade the viewing audience that the “or-ganism” is interacting with that environmentin a convincing manner. One of the most ef-fective component elements that allows per-suasive integration of such characters witha realistic environment are fur, feathers, andtextured clothing. Modeling surfaces as com-plex as animal skins with fur or feathers re-quires that computer programmers and ani-mators deal with an enormous amount ofdata. Not only must every individual hair orfeather be modeled and rendered, but thesurface structure and texture of each mustbe considered, as must the interplay of light,shadow, and translucence of each individualelement. Great care is taken to use biologi-cal reality as a point of reference and depar-ture for hair and feathers. In this regard, indi-vidual morphology, as well as fur and feathertracts are used by modelers and digital art-ists. However, certain compromises are in-evitably encountered. Examples of the solu-tions to these difficulties are demonstratedfrom the film Stuart Little and other projects.

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P1.60 REED, W.L.*, Iowa State University,Ames. The plateau phase in egg metabolicrates: evidence for oxygen limitation.

In bird eggs, rates of gas exchangeacross the shell are limited by diffusion and,thus, a function of the physical properties ofthe shell and the surrounding environment(i.e. conductance, surface area:volume ra-tio). As metabolic rates increase over theincubation period oxygen demand may even-tually exceed oxygen supply and ultimatelylimit metabolism. In many birds a plateau inmetabolic rate is reached prior to hatchingand this plateau may be a function of oxy-gen limitation. I tested this hypothesis byincubating American coot eggs in hyperoxic(60% O2) and normoxic (21% O2) conditions.Metabolic rates of eggs incubated inhyperoxic conditions were greater thanmetabolic rates of eggs in normoxic condi-tions during the last two days prior to con-vective breathing. This suggests that me-tabolism is compromised by diffusion of oxy-gen across the shell late in incubation andthe plateau phase of metabolic rates is dueto oxygen limitation. Hatchlings from thehyperoxic treatment were heavier thanhatchlings from the normoxic treatment, how-ever most of this mass difference was duechicks from the hyperoxic incubation envi-ronment having more water in their tissuesthan chicks from the normoxic incubation en-vironment.

P3.102 REES, B.B*, SUDRADJAT, F.A.,LOVE, J.W., University of New Orleans. Ac-climation to hypoxia increases survival timeof zebrafish during lethal hypoxia.

Survivorship of zebrafish, Danio rerio,was measured during lethal hypoxic stressafter pre-treatment in water at either ambi-ent oxygen or at a lowered, but non-lethal,level of oxygen. Acclimation to non-lethalhypoxia (ca. 10% air-saturation) for 48 h sig-nificantly extended survival time during moresevere hypoxia (ca. 5% air-saturation) com-pared to survival of individuals with no priorhypoxic exposure. The magnitude of theacclimation effect depended upon the sexof the fish; hypoxia pre-treatment increasedthe survival times of males by a factor of ap-proximately 9, and that of females by a fac-

tor of 3, relative to controls. In addition, sur-vival time of control and hypoxia acclimatedfish depended upon when in the year ex-periments were conducted. Survival timeswere 2 to 3 times longer when measured inthe late fall or winter compared to survivaltimes measured during the spring or sum-mer. These results demonstrate a direct sur-vival benefit of short-term acclimation to hy-poxia in this genetically-tractable fish. Thefact that the acclimation effect dependedupon the sex of the fish and the season dur-ing which experiments were conducteddemonstrates that other genetic and/or en-vironmental factors affect hypoxia tolerancein this species. This work was supported byNational Science Foundation grant IBN9723050 (to BBR) and by a student intern-ship from the Freeport-McMoRAN Founda-tion (to FS).

54.2 REES, B.B.*, SCHULTE, P.M., Univer-sity of New Orleans, Louisiana, University ofWaterloo, Ontario. Is intron 2 of the funduluslactate dehydrogenase B gene a hypoxiaresponsive element?

Previous studies have shown that liverlactate dehydrogenase B (LDH-B) activityincreases during hypoxic exposure of F.heteroclitus. Several glycolytic genes inmammals are known to be upregulated dur-ing hypoxia via the binding of hypoxia-in-ducible factor (HIF-1) to a conserved se-quence motif, the hypoxia responsive ele-ment (HRE). The F. heteroclitus Ldh-B genecontains a putative HRE in the second in-tron, which might be involved in the up-regu-lation of this gene in response to hypoxia.We used two complementary approachesto evaluate this hypothesis. First, we rea-soned that if this DNA element were func-tionally important it would be conservedamong multiple species. Therefore, we se-quenced intron 2 of Ldh-B from 13 speciesin the genus Fundulus. The 3' region of theintron was highly conserved and contained2 putative HREs and a sequence similar tothe mammalian cyclic AMP responsive ele-ment (CRE). The number and spacing ofthese elements is virtually identical to thearrangement of elements in the hypoxia re-sponsive promoter of mammalian Ldh-A. Inaddition, we assessed the capacity of this

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intron to confer hypoxia-inducibility uponreporter gene expression using in vivo tran-sient transfection. Although the addition ofintron 2 upstream of the minimal Ldh-B pro-moter led to a marginal increase in reportergene expression during normoxia, intron 2failed to enhance gene expression underhypoxia. In this experiment, however, therewas no increase in LDH-B enzyme activity,suggesting that the fish may have respondedbehaviorally or physiologically to environ-mental hypoxia in such a way as to mini-mize tissue hypoxia. We are currently ex-ploring the operation of Ldh-B intron 2 as anHRE in cell culture. Supported by NationalScience Foundation grant IBN 9723050.

P1.54REESE, S. A.*, CROCKER, C. E.,CARWILE, M. E., JACKSON, D.C., ULTSCH,G.R., University of Alabama, Tuscaloosa,San Francisco State University, University ofAlabama, Tuscaloosa, Brown University,Providence, University of Alabama,Tuscaloosa. Habitat selection and the physi-ology of hibernation in common map turtles(Graptemys geographica).

We submerged map turtles (Graptemysgeographica) from Wisconsin in water equili-brated with air (normoxic) and in water equili-brated with nitrogen (anoxic) at 3oC. Beforesubmergence and for periods up to 150 daysof submergence, plasma PO2, PCO2, pH, [Cl-

], [Na+], [K+], total Mg, total Ca, lactate, glu-cose, and osmolality were measured; he-matocrit and body mass were determined,and plasma [HCO3

-] was calculated. Turtlesin anoxic water developed a severe meta-bolic acidosis, accumulating lactate from apredive value of 1.7 to 116 mmol/L, associ-ated with a fall in pH from 8.010 to 7.128.Total calcium and magnesium rose from 3.5and 2.0 to 25.7 and 7.6 mmol/L, respectively,helping to buffer the accumulating lactate.Plasma [HCO3

-] was titrated from 44.7 to 4.3mmol/L in anoxic turtles. Only minor distur-bances occured in those turtles submergedin normoxic water; there was a marked in-crease in hematocrit from 31.1 to 51.9%. Wesuggest that map turtles have an obligatoryrequirment for a hibernaculum that provideswell-oxygenated water and that this require-ment is important in determining their distri-bution.

S8.9 REGA, E.A., Western University ofHealth Sciences. The “dynamic digital hu-man” in research, entertainment and edu-cation.

The demand for human anatomical ma-terial in teaching at the undergraduate andprofessional school level is enormous, asattested to by the sheer volume of (expen-sive) textbooks, manuals and study aids onthe market and the number of academicpositions whose primary teaching respon-sibilities involve medical and allied healthstudents. There exists a widespreadmisperception by many academics that hu-man anatomy consists simply of rote memo-rization; in truth, assisting students in com-ing to terms with the complexities of humanmorphology and movement in three dimen-sions continues to present the greatest chal-lenge for medical educators. Advances incomputer graphic capa-bilites in recentyears should have revolutionised anatomi-cal teaching by allowing students to viewand manipulate quasi three-dimensionaldigital humans. However, existing anatomi-cal software suffers from curious and pro-nounced limitations arising from a typologi-cal and inherently two-dimensional peda-gogical approach. Despite the need, the de-velopment of new software is limited by acost of development which exceeds typicalacademic resources. In this regard, the vastresources of the entertainment industry canbenefit educators. In consultation with aca-demics and medical professionals, SonyImageworks created a dynamic digital hu-man (and gorilla) as part of the computergraphics effects for the Sony film Hollow Man.This material represents one of the closestdigital approximations of human musculo-skeletal morphology and dynamics to date,and will be a resource for teaching (and in-deed research) applications when fully de-veloped for the educational domain.

P1.87REIBER, C.L.*, HARPER, S.L.,NEWELL, C, LAUNDRIE, N, University of Ne-vada, Las Vegas. Cardiac regulation in thegrass shrimp (Palaemonetes pugio): larvaeto adult.

Grass shrimp exhibit an anamorphic de-velopmental pattern where successive lar-val stages show only minor anatomical

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changes. Larval shrimp exposed tostepwise reductions in water oxygen (150,100, 75, 50 and 25 mmHg O2) were moni-tored for cardiac functions. Both heart rateand stroke volume of larval shrimp (stages 6- 10) remained unchanged when exposedto moderate hypoxia (75 mmHg O2; belowthis a bradycardia was observed. Stroke vol-ume remained at normoxic levels which re-sulted in a decrease in cardiac output. Ju-venile and adult shrimp increased heart rateand decreased stroke volume when ex-posed to hypoxic water. This compensatoryresponse maintained cardiac output downto 75 mmHg O2 below this cardiac outputdeclined sugnificantly. This is in direct con-trast to hypoxic responses observed in manyother decapod crustaceans. Adult grassshrimp hearts also show only limited sensi-tivity to the cardioactive substances, GABAand 5-Ht. These results may suggest thatcardiac regulatory mechanisms in decapodsmaybe more diverse than previouslythought.

60.5 REILLY, S.M.*, WHITE, T.D., Ohio Uni-versity, Buffalo State College. Abdominal mo-tor dynamics in mammal locomotion I: asym-metrical modulation of “cross-couplet” bodysupport in trotting opossums.

Electromyographical patterns of abdomi-nal muscles and muscles associated withthe epipubic bones were studied in the Vir-ginia (Didelphis virginiana) and Pygmy(Monodelphis domestica) Opossums duringtreadmill locomotion at different speeds.Both species exhibited a striking pattern ofasymetrical activation of a specific set of ab-dominal wall and epipubic muscles sum-ming to produce a linear pattern of contrac-tion spanning diagonal fore- and hind limbpairs during the time they are supporting thebody during trotting gaits. In effect, a seriesof muscles contract diagonally to stiffen andbend the body during the time that a givendiagonal couplet is on the ground. Theepipubic bones move little and appear toact as a mid-abdominal strut serving to alignand anchor the diagonal muscle array. Thepectineus exhibits a peculiar pattern of iso-metric tetanus during locomotion.

P2.38REINSEL, K.A.*, RITTSCHOF, D.,FORAN, E., FORWARD, Jr., R.B., WittenbergUniversity, Springfield, OH, Duke UniversityMarine Laboratory, Beaufort, NC, Duke Uni-versity Marine Laboratory, Beaufort, NC,Duke University Marine Laboratory, Beau-fort, NC. Larval release behaviors of deca-pod crustaceans: similar responses inshrimp and crabs.

Ovigerous brachyuran crustaceans re-spond to peptide pheromones from devel-oping embryos with stereotyped larval re-lease behavior. This behavior involves rhyth-mic motion of the pleopods (pumping), whichventilates the egg mass and facilitates hatch-ing of the embryos. We conducted behav-ioral studies using two European shrimpspecies, Paleomon serratus and Crangonvulgaris, and the North American grassshrimp Palaemonetes vulgaris to determinewhether shrimp responses parallel pub-lished observations of brachyuran crabs.Focal stimulation of pleopods with crushedembryo extracts evoked pumping behaviorin all 3 shrimp species. The rate of pumpingin response to the stimulus increased withincreasing embryo concentration. Bradyki-nin, a larval release peptide mimic, alsoevoked increased pumping responses in P.serratus and C. vulgaris. These results areconsistent with observations of brachyurancrabs. In P. serratus, focal stimulation ofaestetasc hairs evoked flicking of the anten-nules, whereas stimulation of the first walk-ing legs evoked feeding responses; neitherstimulated pumping. These results indicatethat the receptors that mediate pumpingbehavior in shrimp are located on the pleo-pods.

P3.23A REITZEL, A.M., MINER, B.G.; Uni-versity of Florida. Spawning times and theimportance of development time in life his-tory models of marine invertebrates.

Trade-offs between fecundity and devel-opment time have been used in life historymodels to predict the optimal amount ofmaternal energy to supply eggs. However,there is very little evidence to support thatselection favors shorter development time.Other factors like juvenile fitness, exogenousfood, larval transport, and fertilization suc-

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cess may influence the evolution of life his-tory and maternal reserves. Here we indi-rectly test the importance of developmenttime on spawning season. In particular, welook at spawning times in species of marineinvertebrates with lecithotrophic larvae (non-feeding). We assume species withlecithotrophic larvae will be more flexible inthe time in which they can spawn, since lar-vae can develop when food is present ornot. Additionally, without the need to feed,temperature will most influence develop-ment time. We therefore predict that speciesthat produce lecithotrophic larvae will spawnjust prior to the warmest seasonal seawatertemperatures. However, other selectivepressures may be important if lecithotrophiclarvae develop during colder months. Wesurveyed spawning times for species withplanktotrophic (feeding), lecithotrophic, andbrooded larvae from the Pacific Northwest.Water temperatures for ten years were com-pared to spawning times to test our predic-tion. Species with planktotrophic larvae typi-cally spawned throughout spring and sum-mer. Species with lecithotrophic larvae weremostly restricted to the months June throughAugust, with the exception of annelids. Spe-cies with brooded larvae were typically foundto brood year around. Water temperaturesand spawning time did not match the pre-diction that development time influencesspawning times and are not consistent withthe theoretical model’s parameters.

P3.106 REMAGE-HEALEY, L., ROMERO,L.M.*, Tufts University, Medford, MA. Effectsof insulin and corticosterone on stress incaptive starlings: daily and seasonal varia-tions in metabolite responses.

Captive starlings (Sturnus vulgaris) wereused to examine the effects of exogenousinsulin and corticosterone administration onplasma metabolite levels in response tostress, and how these responses varied overthe course of the day and season. Starlingswere captured from the wild during the win-ter, held on short days (11L:13D - mimickingwinter), and then shifted to long days (19L:5D- mimicking summer). Levels of corticoster-one (CORT), glucose, and triglycerides weremeasured in blood plasma. Basal sampleswere taken within 3 min of disturbance and

subsequent concentrations were measured40, 70, and 150 min following handlingstress and injection of exogenous saline, in-sulin or CORT. Both triglyceride and CORTconcentrations responded to handling andrestraint stress in control (saline-injected)birds when monitored at both morning andnight, while control birds only exhibitedstress-induced hyperglycemia at night(23:00) and not during the day (11:00). BasalCORT levels were higher at night than dur-ing the day, opposite of the circadiel varia-tion in basal glucose concentrations, andtriglycerides showed no daily variation. In-jected insulin did not affect circulating CORTor triglyceride concentrations but significantlylowered plasma glucose (hypoglycemia). In-jected insulin + injected CORT did not affecttriglyceride concentrations but CORT ap-peared to hasten plasma glucose recoveryfrom insulin-induced hypoglycemia. Thesefindings provide evidence of a possible per-missive role of glucocorticoids in the stressresponse in birds.

P3.106A REMAGE-HEALEY, L., ROMERO,L.M., Cornell University, Tufts University. Cor-ticosterone and insulin interact to regulateglucose and lipid concentrations duringstress in starlings undergoing molt.

Captive starlings (Sturnus vulgaris) un-dergoing a prebasic molt (the costly replace-ment of body feathers) were given exog-enous insulin and corticosterone (CORT) todetermine how counterregulatory hormonesalter glucose and triglycerides during stress.Experiments were conducted at both morn-ing (11:00) and night (23:00) to monitor dailyvariation in responses. Concentrations ofCORT, glucose and triglycerides were mea-sured in blood plasma at <3 min (basal) andat three time points over 2.5 hours thereafter(stress-induced) to monitor the effect of in-jected saline, insulin or CORT. Birds wereexposed to handling and restraint stress,which caused an increase in CORT con-centrations, a decrease in triglycerides, buthad no effect on circulating glucose.Circadiel (daily) variation was not evident inCORT or glucose, but concentrations of trig-lycerides were higher at night than duringthe day. Insulin markedly suppressed glu-cose concentrations, and had no effect on

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plasma CORT or triglycerides. InjectedCORT hastened the recovery of glucoseconcentrations from insulin-induced hy-poglycemia, while CORT had no effect onplasma triglycerides. Exogenous CORT alsoproduced considerable hyperglycemia inthe absence of injected insulin, and this ef-fect was demonstrated at both times-of-day.Basal concentrations of CORT, glucose andtriglycerides exhibited circannual (seasonal)variation when combined with data from anearlier study of starlings held on short andlong days. During the energetically-costlyprebasic molt, all three indicators were atlower basal concentrations than during simu-lated winter (short days) or summer (longdays). These results further demonstrate thesubstantial alteration of metabolism andstress physiology in birds undergoing molt,and present evidence for a permissive roleof glucocorticoids during stress.

P2.44RICHARDSON, J.F.*, ERNST, H.H.,SATTERLIE, R.A., Arizona State University.Pleural ganglion asymmetry in the sexuallyimmature and mature pteropod mollusc,Clione limacina.

In immature specimens of the pteropodmollusk Clione limacina, the right pleuralganglion is slightly larger than the left. Theaverage diameter of the former is 180um,while that of the latter is 160um. The right-to-left diameter ratio is 1.13. In mature ani-mals, average diameters are 300um for theright ganglion and 200um for the left, for aright-to-left diameter ratio of 1.50. A left-to-left ganglion comparison of mature vs. im-mature animals yields a diameter ratio of1.25, while a right-to-right ganglion compari-son gives a ratio of 1.67. Thus, the right pleu-ral ganglion grows out of proportion to theleft with development of sexual maturity. Cellcounts were conducted to determine if theincrease in size was due to an increase ofcell number, an increase in cell size, or both.Initial cell counts utilizing the fluorescentnuclear dye, Hoechst 33342, indicate a sig-nificant increase in cell number in the rightpleural ganglion when comparing immatureto mature animals. The sexual maturity-on-set changes in the pleural ganglia parallelsignificant development of both male andfemale reproductive structures.

P1.29RIDGWAY, R.L.*, CHEUNG, M.B.,BARLAM, I., Seattle Pacific University.Hemocyte activation in molluscs is inhibitedin the presence of a Ca2+-chelating buffer.

In the snail Lymnaea stagnalis, hemocyteactivation is correlated with a rapid shift incytoskeletal organization that facilitatesamoeboid movement and cell aggregation.Activation involves characteristic stages: 1)substrate attachment, 2) spreading/flatten-ing out, 3) generation of lamellipodia/filipodia, 4) random motility, 5) directed mo-tility/phagocytosis, and 6) hemocyte aggre-gation/fibroblast-like morphology. Previ-ously, a chelating buffer (containing 2 mMNa2-EDTA) was shown to prevent hemocyteaggregation (Adema et al., Dev. Comp.Immunol. 18: 25-31, 1994). We employedthis buffer to examine the effects of loweringextracellular Ca2+ on the time course ofhemocyte activation and the shift in organi-zation of microfilaments/microtubules. In thepresence of the chelating buffer hemocyteswere slower to attach to the substrate, butreached stage 3 in roughly the same time(5-10 min) as control preparations. After 15min of exposure to EDTA, however, mosthemocytes began to round up (reverting tostage 1) and their degree of microfilament/microtubule organization was significantlydecreased. These results support our hy-pothesis that Ca2+ concentration, perhapsmediated by Ca2+-binding proteins, under-lie the cytoskeletal changes associated withhemocyte activation.

11.1 RIEHLE, M. M.*, BENNETT, A.F.,LONG, A.D., University of California, Irvine.Genetic analysis of the adaptation to tem-perature stress: a role for gene duplications.

Additional copies of certain genes or generegions have been implicated previously asinstrumental players in organismal adapta-tion to environmental stresses, especially asa means for gene amplification in microor-ganisms. Six lines of high temperature(41.5ƒC) adapted Escherichia coli werescreened for gene duplications and dele-tions using DNA high-density array technol-ogy. Three of the six selected lines contain aregion of gene duplication at least 23.7 kb insize at the 59th minute of the chromosome.This duplicated region contains genes that

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have previously been shown to enhance sta-tionary phase survival under benign orstressful conditions and to help in the repairof damaged proteins. Expression of twocandidate genes in the lines with the geneduplication is significantly elevated overancestral expression levels. In the two caseswhere the duplication at 2.85MB has beenfurthered characterized, the timing of the ge-nome reorganization is coincident with sig-nificant increases in relative fitness. Thesesix lines of high temperature adapted bacte-ria have now spent 2000 additional genera-tions back at their ancestral temperature of37ƒC and we will determine (1) how theirrelative fitness has changed at both hightemperature and at 37ƒC and (2) whetherthe bacteria still contain the duplication atthe 59th minute that originated during the2000 generations at high temperature orhave they reverted back to their ancestralhaploid state. Supported by NSF-IBN9507416, NSF-IBN 9905980 to AFB, NIH-GM 58564 to ADL and a NSF PredoctoralFellowship to MMR.

71.4 RIMKUS, T.A.*, SIEBERT, C.A.,SELBY, D.M., Marymount University. Leadanalysis of snapping turtle (Chelydraserpentina) hatchlings exposed to lead ni-trate at various times during incubation.

Eggs from three female snapping turtleswere incubated in sand with a water contentof 4% by mass. This is equivalent to beingexposed to a water potential of -7 kPa. Threeeggs from each female were exposed to leadnitrate for 48 hours on days 0, 15, 21, 30, 40,and 50 of incubation. A 0.01M lead nitratesolution was used to wet the sand to 4%water content. The eggs were then incu-bated in the absence of lead nitrate for theremainder of incubation. The hatchings weresubsequently sacrificed and analyzed forlead. Hatchlings that were exposed to leadnitrate at the beginning of incubation hadhigh levels of lead (1.54 ppm) whilehatchlings that were incubated after day fif-teen had lead levels (0.050 ppm) not signifi-cantly different from the controls (0.043 ppm).During the time of exposure to the lead ni-trate, the eggs did take up water. These re-sults support the hypothesis that egg waterexchange during the later stages of incuba-

tion should be in the vapor phase, so as notto interfere with gas exchange.

P2.19RIORDAN, T.J.*, LINDSAY, S.M., Uni-versity of Maine. Chemically stimulated de-posit-feeding in the spionid polychaete,Polydora quadrilobata.

In marine soft-sediment habitats, chemi-cal sensing by deposit feeding organismsmost likely plays a critical role in feedingbehavior, yet few specifics about this roleand its ecological implications are known.As part of a multi-disciplinary investigationof chemoreception in the spionid polycha-ete Polydora quadrilobata, we have identi-fied several phagostimulatory chemical cues.Using glass beads as a proxy for sediment,we tested for feeding responses to a se-lected number of potential cues that mightbe used to indicate food availability or qual-ity. We presented two sets of beads to indi-vidual intact worms: one with and one with-out covalently bound compounds such assingle amino acids, mixtures of amino ac-ids, and single simple sugars. Worms wereexposed to the beads under slow flowingseawater so that any dissolved cues wereflushed from the test chamber. Each wormwas videotaped for fifteen minutes immedi-ately following the addition of beads andthese records were scored for the time theworm spent in a variety of behaviors. Re-sponses to beads with and without cueswere compared to identify compounds asstimulatory, inhibitory, or inactive. Cues elic-iting significant behavioral responses will beused in future neurobiological examinationsof this species to identify and localizechemoreceptor cells. Supported by NSFgrant OCE-9973327 to SML.

11.3 ROBERTS, S. P.*, FEDER, M.E.,POSLUSZNY, J.A, University of Nevada LasVegas, The University of Chicago, The Uni-versity of Chicago. Developmental and fit-ness consequences of natural thermal stressand Hsp70 copy number in Drosophilamelanogaster.

Natural heat exposure of larval Droso-phila melanogaster results in high rates oflarval mortality and severe developmentaldefects in eclosing adults. Transgenic in-creases in copy number of the gene encod-

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ing the major inducible heat-shock protein(Hsp) of D. melanogaster, Hsp70, mitigatethese effects yet increase mortality duringbenign thermal conditions. In two wild D.melanogaster populations studied, approxi-mately 10% of adult flies reared from field-collected fruit had severe developmentalanomalies of wing and abdominal morphol-ogy. The frequency of developmental ab-normalities varied along a natural thermalgradient, reaching 4% in adults eclosing fromlarvae developing in cool, shaded fruit andexceeding 12% for flies from warm, sunlitfruit. Heat-induced wing deformities dramati-cally reduced mating success in male flies.When exposed to strong natural heat stress,D. melanogaster with the wild-type numberof Hsp70 genes (10) had higher rates of lar-val mortality and developmental disruptionthan a transgenic sister strain with additional(22) copies of the Hsp70 gene. However,under conditions of little or moderate natu-ral thermal stress, larvae possessing 22Hsp70 copies had higher mortality rates thanlarvae possessing 10 Hsp70 copies. Theseresults support the hypothesis of an evolu-tionary trade-off of the benefits and adverseconsequences of Hsp70 expression.

P3.90ROBERTS, S.A.*, MOORE, P.A.,HUBER, R., HECKMAN, C., CAYER, M.,Bowling Green State University. Immunocy-tochemical localization of Met-enkephalin incrayfish eye stalk.

Experimental investigation into the effectof chemical signals in the nervous system ofcrayfish has shown certain neurotransmit-ters, such as seratonin and dopamine, havethe capability of altering the aggressive ten-dencies of crayfish in a hierarchical commu-nity. While such studies are becoming welldocumented, a third group of polypeptideneurotransmitters, enkephalins, have gonerelatively unstudied. Enkephalins are be-lieved to function in a manner echoing thatof seratonin and dopamine, however, thelack of research into these chemical signalsprovides only a small platform from which toembark onto further study. The goals of thisstudy are two fold. First, it attempts to deter-mine the relative dispersion of Met-enkepha-lin in the crayfish eye stalk, where unusuallylarge amounts of enkephalins have been

reported. Secondly, it strives to identify thespecific location of high concentration cen-ters of the neurotransmitter in the hopes oflending information towards the functioningof these chemicals within the crayfish ner-vous system and possible behavioral effectscaused by the presence of the neurotrans-mitter. Results appear to indicate localiza-tion of enkephalin or enkephalin-like mol-ecules within the eye stalk, depicting speci-fied use of the neurotransmitter. Ultimately,the wide range of organisms that utilize en-kephalins in their nervous systems providesa strong possibility for extrapolation of en-kephalin effects to other complex organismsform a crayfish basis.

22.1 ROBERTS, T.J.*, SCALES, J.A., Or-egon State University. The source of powerfor acceleration in turkeys.

Many of the features that make somemuscle-tendon units effective as springsduring running - long tendons, short musclefibers, articulations across more than onejoint - may make them ill-suited to perform-ing mechanical work. It has been suggestedthat the work required for activities such asuphill running or acceleration is producedby long-fibered muscles of distal limb seg-ments. We measured the work done at indi-vidual joints in wild turkeys during accelera-tion to determine which muscles provide thework of acceleration. Force-plate and high-speed video measurements were used tomeasure joint work during single footfalls asturkeys accelerated along a 10 meter track-way. The net work per step at the hip and theankle increased in direct proportion to therate of acceleration. At the ankle, a decreasein joint flexion and an increase in joint ex-tension contributed to the total increase innet work output. Hip work was increased byincreasing the joint extension from an aver-age of 12o during steady speed running toabove 40o at the strongest accelerations. Theknee and tarsometatarsal-phalangeal jointdid not contribute to the work of accelera-tion, as net work output at these joints wasindependent of acceleration rate. Net workproduced for the most rapid accelerationsaveraged 0.9 J/kg body mass at the hip and0.8 J/kg body mass at the ankle. The largemuscle masses at the ankle and the hip ap-

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pear to be equally important for providingthe work necessary for acceleration. Thehigh work output of ankle extensors indi-cates that while long tendons and short fi-bers may improve a muscleís ability to de-velop force economically, they do not nec-essarily limit its ability to perform mechani-cal work. Supported by the Medical Re-search Foundation of Oregon and NIHAR46499 to TJR.

P3.3 ROBESON II, M.S.*, GAREY, J.R.,University of South Florida. The mitochon-drial genome of the rotifer Brachionusplicatilis.

There are no published sequences of thecomplete mitochondrial genome from a roti-fer. The mitochondrial genome of differentisolates of the rotifer Brachionus plicatilis varyin size from 16-26 kilobases (kb). About 12kb from an isolate with a genome totalingapproximately 16-20 kb was sequenced. Thecontiguous stretch contains the genes for11 tRNAs, 2 rRNA genes, 4 protein codinggenes (NADH dehydrogenase 1, NADHdehydrogenase 2, ATPase 6, and cyto-chrome b). The remaining sequence appearsto be non-coding. The expansion or contrac-tion of this non-coding region may accountfor the variation in mitochondrial genomesize from different isolates. Currently an at-tempt is being made to PCR amplify andsequence the remaining mitochondrial ge-nome. The order of the genes and the se-quences of the genes will provide phyloge-netic information to help elucidate the rela-tionship of rotifers to other metazoans. Thesequence of this genome will make it easierto PCR amplify mitochondrial genes fromother rotifers, facilitating studies of the evo-lutionary relationships among rotifers.

S13.4ROEN, D.*, WHITMER, A. C., ArizonaState University, Tempe. Learner-centeredapproaches in biology.

What is learner-centered education? Howis it distinguished from learning-centerededucation? What is the value of these ap-proaches? How can biology faculty applyprinciples of these approaches to reinvigo-rate teaching and enhance learning? Howcan faculty use these approaches in largeclasses? We will address these and other

related questions as we offer some strate-gies for promoting active learning for stu-dents in a variety of settings - in a lab, in alarge lecture class, in a small discussiongroup, sitting alone at a computer, alone witha book. We will also engage the audiencein several activities to demonstrate their use.

P3.61ROIG-LOPEZ, J.L.*, SAN-TIAGO, P.,NIEVES, L., JIMENEZ, B., GARCIA-ARRARAS, J.E., University of Puerto Rico,Rio Piedras., Medical Sciences Campus,University of Puerto Rico. Differential expres-sion of actin isoforms during intestinal re-generation in the sea cucumber Holothuriaglaberrima.

The regeneration capability of echino-derms is well known, however, few stud-ies have focused on the cellular and mo-lecular events underlying this phenom-enon. We are using the sea cucumberHolothuria glaberrima as a model systemto elucidate the molecular aspects of re-generation. Differential display analysisbetween normal and regenerated tissuesproduced a series of bands preferentiallyexpressed in the regenerated tissue.These bands were used as probes toscreen a regenerated tissue cDNA expres-sion library, from which two actin cDNAclones, HgAct1 (2.0 Kb) and HgAct2 (2.2Kb), were obtained. A possible third actinisoform HgAct3 (280 Bp) was cloned byPCR using rat actin primers. Two lines ofevidence suggest that HgAct1 and HgAct2are different isoforms: partial sequenceanalysis, including the 3í UTR, show nosignificant similarities between them andnorthern blots with one probe show mul-tiple bands with differential expressionpatterns at various regeneration stages.A prominent signal of approximately 2.5Kb shows an up-regulation during earlyintestinal regeneration when compared tolate regenerate and normal tissues. Theexpression of actin isoforms is known tobe developmentally regulated during em-bryogenesis in vertebrate and invertebratedeuterostomes, but few studies have ad-dressed their regulation during regenera-tion. The regulated expression of these ac-tin isoforms can be associated with impor-tant events in the regeneration process,

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such as, cell differentiation and migration.Supported by: NSF-EPSCoR (OSR-9452893); NIH-MBRS (RR-8102-18); NIH-RCMI (RR03641-02); and the Universityof Puerto Rico.

59.4 ROMMEL, S.A.*, PABST, D.A.,MCLELLAN, W.A., Florida Marine ResearchInst., University North Carolina atWilmington, University North Carolina atWilmington. Convergent evolution in the vas-cular systems of three marine mammals.

Conservation of thermal energy inaquatic mammals is essential for the main-tenance of high core temperatures in a heatconducting aquatic environment. Seals, dol-phins, and manatees have gross morpho-logical adaptations such as large size, modi-fication of appendages, and blubber to con-serve body heat. Additionally, they possessvascular countercurrent heat exchangers intheir extremities. Nevertheless, the need forheat conservation is balanced by an equallyimportant need for selective heat dissipa-tion to protect susceptible organs, such asthe testes and epididymides, from hyperther-mic insult. Seals, dolphins, and manateesare ascrotal, increasing the potential for hy-perthermic insult. However, specialized vas-cular designs enable the selective coolingof these thermally sensitive tissues. Vascu-lar structures that prevent reproductive hy-perthermic insult in seals, dolphins, andmanatees are reviewed and physiologicalevidence to support these anatomical ob-servations is presented. Each of these ma-rine mammals possesses vascular shuntsassociated with the testes and epididymides.These shunts are parallel to the countercur-rent heat exchangers, connecting superfi-cial vascular beds and deep vascular plex-uses. The thermo-vascular “circumventions”are convergent adaptations across threediving mammalian groups with independentevolutionary histories.

15.3 ROSEN, G.*, WADE, J., Michigan StateUniversity, East Lansing. Androgen metabo-lism in the green anole lizard brain.

5ALPHA-reductase facilitates male court-ship behavior in green anole lizards by con-verting testosterone (T) to dihydrotes-tosterone. The present study was done to

determine whether sex and seasonal differ-ences in the enzymeís activity occur in theanole brain, reflecting its role in male court-ship behavior. The pattern of expression alsowas assessed for aromatase, which con-verts T to 17BETA-estradiol. Multiple assayswere done to compare enzyme activities inthe following: 1) breeding males and breed-ing females; 2) breeding males and non-breeding males; 3) non-breeding males andnon-breeding females. Enzyme activity wasassayed in homogenates of individual wholebrains. 5ALPHA-reductase was also as-sessed in brainstem homogenates, sincethis region contains the greatest level of ac-tivity for this enzyme. Breeding males, breed-ing females and non-breeding males hadequivalently high 5ALPHA-reductase activ-ity. In contrast, breeding males had greateraromatase activity than breeding femalesand non-breeding males. The results aregenerally consistent with those of other ver-tebrate species in which sex and seasonaldifferences are present in aromatase, butnot 5ALPHA-reductase. The greateraromatase activity in breeding males indi-cates that this enzyme might mediate male-specific functions, although the behavioralrelevance of this enzyme in male anoles isunclear. The high levels of 5ALPHA-reduc-tase activity in both sexes suggests that theenzyme might have important functions infemales as well as in males.

3.1 ROSENBERGER, L.* J., WALKER, J.A., COLLAR, D., WESTNEAT, M. W., FieldMuseum of Natural History, University ofSouthern Maine, Field Museum of NaturalHistory, Field Museum of Natural History.Effects of fin shape and fin motion onlabriform swimming performance.

Labriform locomotion in fishes is per-formed by either rowing or flapping the pec-toral fins. In this study, we tested a priori hy-potheses of causal associations between finshape, fin kinematics, and swimming per-formance using a diverse group of wrasses(Labridae) differing in fin and body shape,swimming behavior, and phylogenetic posi-tion, including members of the generaBodianus, Cheilinus, Choerodon, Coris,Cirrhilabrus, Gomphosus, Halichoeres,Thalassoma, Tautoga, Scarus and others.

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Locomotor performance was determined asthe maximum swimming velocity that fishesattained using strict pectoral-based locomo-tion. Critical swimming speed ranged fromabout 3 body lengths per second up togreater than 5 bl/s in the taxa sampled. Finshape is a major determinant of labriformpropulsion mechanics, as wrasses rangefrom extremely paddle-like fins (e.g. Tautogawith an AR of 1.5) to highly tapered and wing-like fins (e.g. Gomphosus with an AR of 3.5).To assess differences in kinematics of spe-cies on the rowing to flapping continuum,we calculated stroke plane angle, frequencyand amplitude in all species. Our resultsshow that maximum pectoral-fin-poweredswimming speeds were higher in wrassesthat had a more vertical stroke plane angleand higher aspect ratio (more wing-like) fins.Recent models suggest that there may be atrade-off between swimming performanceand rapid force production for higher ma-neuverability that may have resulted in re-peated evolution of these two alternativestrategies in the family Labridae. ONRN000149910184 and NSF DEB- 9815614.

S10.13 ROWAN, R.; University of GuamMarine Laboratory. Evolutionary and eco-logical dynamics of coral-zooxanthellasymbioses.

Many tropical marine invertebrate ani-mals harbor endosymbiotic algae. Reef-building corals are the best-studied ofthese symbioses. These corals host zoox-anthellae that are far dinoflagellates in thegenus Symbiodinium. Earlier views of cor-als as “one host-one symbiont” associa-tions have been challenged by molecularstudies of zooxanthellar taxonomy, whichshow that some coral species encompassmore than one species of Symbiodinium.The non-random distribution of these poly-morphic symbioses implies that corals ac-climatize to different environments by host-ing differently-adapted Symbiodinium spp.Examples from the Caribbean (corals inthe Montastraea annularis species com-plex) and the Pacific (the coral Pocilloporadamicornis) will be presented. Disturbanceexperiments on M. annularis imply that theirzooxanthellae include species ofSymbiodinium that range from “weeds” to

narrowly-adapted specialists, whose dy-namics may have parallels with the dy-namics of plant communities. An under-standing of these processes is relevant topredicting the response of corals and coralreefs to climate change.

35.4 RUBEGA, M.A.*, HEATH, K.M., Uni-versity of Connecticut, Storrs. Skeletal de-velopment in hatchling avocets and stilts: theeffects of salt stress on growth and ossifica-tion.

Post-hatching skeletal development innon-galliform precocial birds is less well-known than is embryonic development, andthe effects of stress during growth are evenless studied. Many studies have shown thathigh salinity levels are lethal to hatchlingbirds, but the effects of sublethal levels ofsalt stress on ultimate adult form and func-tion are completely unknown. We examinednormal and salt-stressed American avocet(Recurvirostra americana) and black-necked stilt (Himantopus mexicanus) chicks(0 - 14 days post-hatching) for the effects ofsalt stress on skeletal development. Mea-surements of cleared and stained speci-mens revealed that salt stress stunted growthin avocets, but did not suppress ossification.Salt-stressed avocets were smaller becauseof reduced bone growth, but proportionallymore ossified because ossification pro-ceeded despite salt stress. The patterns ofsalinity effects on the development of theskeleton in stilts were more ambiguous.These patterns suggest that the ontogeny ofossification may be invariant, and thus maypartly explain observations of reduced ulti-mate adult size in birds subjected to otherforms of stress during the postnatal growthphase.

P1.11RYAN, W.L.*, SCATCHARD, K.,BRADY, B., Kutztown University of Pennsyl-vania. Preliminary findings from a study ofgas bubble disease in embryos and fry ofthe japanese medaka (Oryzias latipes).

Gas bubble trauma is known to causesubstantial morbidity and mortality of fishresiding in gas supersaturated water. Thetrauma results from gas bubbles in the vas-cular system and other locations, causinga variety of physiological problems. Much

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interest in this topic is related to the con-trolled spilling of water from dams and theresulting gas supersaturation. Previousstudies have examined the susceptibilityof juvenile and adult fishes, but little workhas been done to determine the responseof developing stages to gas supersatu-rated conditions. This study focused onthe exposure of embryos and newlyhatched fry of the Japanese Medaka,Oryzias latipes, to very low gas supersatu-rations (ranging from 102 to 110% satura-tion). The gas supersaturation was estab-lished using a bubble column and wasmaintained for days at a time. Water waspumped from the aquarium and forceddown an inner PVC pipe, exiting near thebottom of the column into an outer pipe,then ascended between the two pipes tothe exit point and back to the tank. Airwands within the pipes generated the gassupersaturation. Each individual embryoor fry was observed daily for the diagnos-tic features of gas bubble disease and anyother developmental abnormalities. Inaddition, digital images of each organismwere analyzed in order to quantify the sizeof any gas bubbles or abnormalitiespresent. Preliminary results show only asmall percentage (<5%) of the embryosand fry exposed to these conditionsshowed abnormalities, none of whichwere characteristic of gas bubble trauma.In addition, no internal gas bubbles wereobserved. Further study is needed to fullycharacterize the response of the embryosto these potentially lethal environmentalconditions.

S10.1SAFFO, M.B., Arizona State Univer-sity West. Symbiosis: a complex and deli-cate balance.

Symbiotic associations are intimate as-sociations among two or more species. Suchinterspecific intimacy can have diverse evo-lutionary outcomes, ranging from antagonis-tic interactions (parasitisms and pathogenicassociations) to mutualistic ones. Even whenwell understood (and many are not), the dy-

namics of many symbiotic associations re-sist simple definition. Many multi-partnersymbioses embrace both antagonistic andmutualistic species interactions within asingle association.Many others vary in theireffects over time and space, depending onthe particular environmental conditions, de-velopmental stages, and species partnersinvolved; such examples suggest that theboundary between antagonistic and mutu-alistic symbiosis can be a thin and variableone. Recent symbiosis research, particu-larly on mycorrhizae and coral-dinoflagel-late symbioses, but also on numerous othersystems, has revealed, with compelling andinstructive detail, the depth and extent of theecological and evolutionary complexities ofsymbiont interactions in both plant and ani-mal hosts. Ongoing investigations also con-tinue to confirm the geographical and taxo-nomic ubiquity, and ecological and evolu-tionary (including agricultural and medical)importance of both parasitic and mutualisticsymbioses. Drawing on symbiosis researchon plant and animal (as well as computer)hosts, from marine, freshwater and terres-trial habitats, and on integration of molecu-lar, ecological and systematic approaches,this symposium seeks to explore the com-monalities between parasitic and mutualis-tic symbioses, and also to gather fresh in-sights from exploration of their differences.

S5.5 SAGE, R.F., University of Toronto. Howplants sense, signal, and respond to carbondioxide.

Most effects of atmospheric CO2 increasearise indirectly as a result of photosyntheticstimulation, inhibition of respiration, or im-proved water use efficiency. Only the guardcells that control stomatal function are knownto directly sense variation in CO2 and trans-duce it into a regulated response. High CO2reduces stomatal aperture, while low CO2increases it. The mechanism of this signal-transduction response remains unclear. Atthe level of the internal leaf biochemistry, theexpression of only a few enzymes may bedirectly regulated by CO2 level. For example,

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carbonic anhydrase expression is reducedby high CO2, but the mechanism for thiscontrol is also unclear. Increasing CO2 pro-motes photosynthesis through its effect as asubstrate in carbon fixation and as an in-hibitor of photorespiration. Long-term(weeks to years) exposure to high CO2 in-creases leaf carbohydrate status, which inturn reduces photosynthetic gene expres-sion, causing a decline in photosynthetic ca-pacity. This reduction in photosynthetic ca-pacity is the main acclimation response tohigh CO2, and is similar to acclimation re-sponses to other environmental agents thatpromote carbohydrate accumulation. Fac-tors that affect carbohydrate accumulationfollowing transfer to high CO2 modulate thestrength of the acclimation response. Forexample, low sink capacity and low nutrientstatus promote carbohydrate accumulationand a strong CO2 acclimation response.Carbohydrates status alone does not driveCO2 acclimation. Instead, it appears leavesmust be primed to respond to high levels ofcarbohydrate, probably by long-distancesignals such as ABAand cytokinins that aresent from the roots and other sinks. Identify-ing the mechanisms of interaction betweencarbohydrate status, plant hormones andother developmental signals is a major re-quirement for understanding how plants willrespond to atmospheric CO2 enrichment.

35.1 SAGE, R.F.*, SAGE, T.L., University ofToronto. Microsites characteristics ofMuhlenbergia richardsonis, an alpine c4plant.

C4 plants are uncommon in cold envi-ronments at high latitude and altitude, andare not generally thought to occur in thealpine tundra. In the White Mountains ofCalifornia, we found that the C4 grassMuhlenbergia richardsonis commonly oc-curs in the alpine zone at 3300 to 3800 m,with the highest population observed 3950m above sea level. This is the highest re-ported C4 plant population in NorthAmerica, and is near the world altitude lim-its (4000 to 4200 m) reported for C4 plantsin Asia and the Andes. At its highest distri-bution (3600 to 3950 m), M. richardsonisis restricted to southeast and southwest

facing slopes, with greatest frequency onsoutheast faces. Muhlenbergia richard-sonis plants form low mats with meanheight of 2.7 cm, while co-occurring C3grasses form bunches that are on aver-age two to three times taller. As a result, M.richardsonis leaves are more affected bythe boundary layer of the soil than nearbyC3 grasses. Temperature of M.richardsonis leaves was over 20ƒC aboveair temperature in full sun and still air, and10ƒC above air temperature in full sun andwind. As a result, midday leaf tempera-tures in M. richardsonis were routinelyobserved to be 25ƒC to 35ƒC, conditionsfavorable to C4 photosynthesis. At night,the high boundary layer in theMuhlenbergia mats allows for 5ƒ to 15ƒCreduction of leaf temperature below airtemperature, resulting in regular frostingof leaves. These results indicate that M.richardsonis requires daytime heating forecological success, and has evolved thecapacity for freezing tolerance at night andearly in the day. The ability to withstandregular freezing suggests that minimumdaily temperature alone cannot accountfor the general absence of the C4 path-way in cold environments. Instead, a fea-ture associated with the daytime heat re-quirement of the C4 pathway may be moreimportant.

57.4 SALVANTE, K.G.*, WILLIAMS, T.D.,Simon Fraser University, Burnaby, BC,Canada. Hormonal control of reproduction:effects of corticosterone on timing of laying,egg size, clutch size, and yolk precursor lev-els.

Egg formation involves major adjust-ments in lipid metabolism, including anupregulation of total lipoprotein synthesis,and production of a specific yolk-targetedvery-low density lipoprotein (VLDL), andvitellogenin (VTG). Corticosterone (B) isknown to be involved in regulating manyaspects of lipid metabolism in non-reproduc-tive animals, including increased fat depo-sition in the liver and adipose tissue andhyperglycemia. We therefore investigatedwhether B is involved in regulating or modu-lating lipoprotein production and metabo-lism during yolk formation, and the effect of

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B treatment on reproductive output (egg size,clutch size, and timing of laying), in zebrafinches (Taeniopygia guttata). Egg-laying fe-males had significantly lower stress-inducedplasma B levels compared with non-breed-ers (8.8 vs. 18.1 ng/ml), although there wasno difference in basal B levels (3.2 vs. 3.3ng/ml). Egg-laying females were treated withexogenous corticosterone using silastic im-plants, and this elevated plasma B to highphysiological levels (23.5 ± 7.8 ng/ml). B-treated females were less likely to lay eggsand also had a longer laying interval com-pared with control females. Effects of B onegg size and clutch size, as well as onplasma levels of the two yolk precursors, VTGand VLDL, will also be described.

P2.50SANDERS, N.K.*, MAYO, M.,STUART, J., Truman State University. TrumanState University students and evolution: asurvey.

Recent media attention has refocusedthe American public on the teaching of evo-lution in public schools. Nationwide, differ-ences in state standards for science educa-tion offer a wide variety of possibilities of howto teach about evolution ñ or not - for publicschool science teachers. Truman State Uni-versity in northeast Missouri is public liberalarts school in a state that does not mentionevolution in the state science standards.Student writing assignments in introductorybiology over an 8 year period led to my per-ception that many Truman students know littleabout the science of evolution, and havemany major misconceptions about thistheory. A survey was designed to elucidateattitudes toward and understanding of evo-lution by students in Truman biology classes.We predicted that non major biology studentswould have the least understanding of evo-lution, and senior biology majors in thecapstone course would have the greatestunderstanding. Preliminary data support thisprediction.

40.6 SANDERSON, S.L.*, CHEER, A.Y.,GOODRICH, J.S., GRAZIANO, J.D.,CALLAN, W.T., College of William and Mary,

University of California, Davis, PrincetonUniversity, Howard University, College ofWilliam and Mary. How do gill rakers func-tion in suspension-feeding fishes?

Gill rakers have been assumed to serveas either (1) a sieve that accumulates par-ticles larger than the mesh size or (2) a stickyfilter that retains particles encountered via ahydrosol filtration mechanism. However, ourvideo endoscopy (30 - 250 Hz) in the oralcavities of freely-swimming fish during pumpsuspension feeding demonstrates that therakers of species belonging to three fami-lies (gizzard shad, Dorosoma cepedianum;goldfish, Carassius auratus; ngege tilapia,Oreochromis esculentus) do not function asa sieve or as a sticky filter. The gill rakers ofpump suspension-feeding Sacramentoblackfish (Orthodon microlepidotus) havebeen hypothesized to serve as a barrier tofluid flow, directing particle-laden water tothe sticky oral roof where particles aretrapped (Science 251: 1346-1348, 1991).However, our use of computational fluid dy-namics to simulate flow in the vicinity of rak-ers at intermediate Reynolds numbers (250- 500) shows that the rakers of pump sus-pension-feeding fishes are leaky, never serv-ing as a barrier to flow. Based on these re-sults, we propose a new model of filtration insuspension-feeding fishes. Supported byNSF grants to SLS and AYC.

23.3 SANE, S.S.*, DICKINSON, M.H., Uni-versity Of California, Berkeley. Unsteadyaerodynamic forces are important for pro-duction of force moments by flapping wings.

Insects use aerodynamic forces not onlyto stay in air, but also to steer and maneuver.Through changes in wing kinematics, in-sects can finely control the pitch, roll andyaw moments around their body and thusmaneuver. In a previous study, we used amechanical model of a fly to study the influ-ence of wing kinematics on unsteady forcegeneration. In this study, we extend theanalysis to include moments generated dur-ing single strokes. To address how unsteadyforce mechanisms such as delayed stall,wake capture and wing rotation affect mo-ments, we used an extensive data set ofaerodynamic forces corresponding to differ-

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ent kinematic patterns, and calculated theresulting instantaneous pitch, roll and yawmoments throughout the stroke. For the ki-nematics that generated maximum lift, weidentified sub-regions where pitch, roll oryaw are most sensitive to changes in strokeamplitude, angle of attack, flip timing, flipduration and deviation from mean strokeplane, respectively. First, for fixed flip dura-tion and flip timing, all three moments weresensitive to variation in stroke amplitude andangle of attack within a kinematic rangewhere lift is sufficient to support body weight.Second, for fixed stroke amplitude and angleof attack, roll moments vary little withchanges in flip timing or flip duration. How-ever, pitch and yaw moments are sensitiveto changes in flip timing and duration. Third,for fixed stroke amplitude, angle of attack,flip timing and flip duration, all three momentsare very sensitive to variation in the devia-tion from mean stroke plane. This suggeststhat changes in stroke deviation may be anexcellent strategy for manipulation of mo-ments around an insect’s body.

P2.9 SANSTAD, E.A., JARZAB, D.M.,LeCLAIR, E.E., DePaul University. A cDNAcatalog of turtle shell development.

In turtles, the cranial and postcranial der-mal bones are remarkably similar in struc-ture, containing both sutures and plates. Thisleads to the question of how the vertebrategene families that regulate mesodermal fateand intramembraneous bone formationhave been co-opted to a different role in turtleshells. Using histological techniques wehave cleared and stained the shells of de-veloping turtle embryos (Chrysemys scripta)after 2 weeks, 3 weeks,5 weeks and 7 weeksof incubation. This allows us to study theprogress of ossification as the shell devel-ops. Next, we have created three tissue-specific cDNA libraries from the lateral cara-pace ridge (which initiates shell develop-ment), the 3-week embryonic shell (cartilagi-nous phase) and the 5-week embryonicshell (ossification phase). After reverse tran-scription and long-distance PCR amplifica-tion, all cDNAs were directionally cloned intothe lTriplEx2 vector (Clontech) and pack-aged into phage. Preliminary analysis of theamplified libraries show that the titers ex-

ceed 4-8 million pfu/uL; randomly isolatedphage were sequenced and found to con-tain mid-length (>700 bp) turtle-specificcDNAs, including the 3' poly-A tail. Theselibraries are now being screened for genesinvolved in shell initiation (e.g. FGFs) andthe regulation of growth at bony sutures (Msx,BMPs). Aliquots of these libraries are avail-able to interested researchers. (Supportedby the DePaul University Research Counciland Sigma Xi.)

63.5 SANTAGATA, S.*, ZIMMER, R.L., Uni-versity of Southern California. Muscle, neu-ral, and epithelial tissue variation betweenlarval and presumptive juvenile structuresin different species of actinotroch larvae(Phoronida).

Actinotroch larvae exhibit variationamong several characteristic traits at com-petence. These traits include the structureof the larval and juvenile tentacles and themuscular and neural components of thehood. All actinotrochs develop three me-dian hood nerves at competence, howeverthere are at least two distinct types of neuralstructures associated with these nervesamong different species. One is a second-ary neuropil and the other is a secondarynerve complex that contains scattered sero-tonergic cell bodies. Larval and presump-tive juvenile tentacles show different degreesof cellular integration among species. Cur-rently there are three known designs for theorigin of the juvenile tentacles: the larval ten-tacles are remodeled into the juvenile ten-tacles, the juvenile tentacles develop from abasal primordium attached to the larval ten-tacles, or the juvenile tentacles are devel-oped as a separate set underneath the lar-val tentacles. All species from the two lattergroups form lateral cilia on their juvenile ten-tacle primordia, but these cilia remain im-motile during larval life. The juvenile ten-tacular epithelium of one of these speciesalso selectively labels for serotonin. Larvalcategories based on these characteristicsdo not directly correlate with generic group-ings or reproductive types of the adults ex-cept in the case of Phoronis architecta andP. muelleri. These data also do not supportthe proposed synonymy of P. architecta withP. psammophila.

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31.1 SANTINI, F., University of Toronto. Ori-gin and evolution of the tetra-odontiformes(teleostei, pisces), with an analysis of thepatterns of speciation of the familytriacanthodidae.

Fossil evidence seems to point towardsan origin in shallow waters, during the up-per Cretaceous, of several lineages of Acan-thopterygian fishes, which now are widelydistributed in deep waters. Among thesegroups, we find the Zeiformes, theCaproiformes, and the Tetraodontiformes.This distributional shift probably happenedafter the K/T mass extinction. Possible sce-narios regarding the origin of one of theseclades, the Tetraodontiformes, are presentedand discussed. In addition to this, a phylo-genetic systematic analysis of one of thesegroups, the family Triacanthodidae(Tetraodontiformes, Teleostei) is being uti-lized to test the applicability to marine taxaof methodologies that rely on phylogenetichypotheses and biogeographical distribu-tions to study patterns of speciation. A vari-ety of pioneering studies seem to suggestthat the vast majority of speciation processesin terrestrial and freshwater taxa might bedue to vicariant events. By contrast very pre-liminary work on marine organisms seemsto indicate that different modes of specia-tions might be predominant in the sea, per-haps due to important differences in the re-productive biology of many marine organ-isms. The results of this study are presentedand discussed.

P3.15SANTINI, F., University of Toronto. His-torical biogeography of coral reefs organ-isms: is the indonesian region a center oforigin?

Historical biogeography is the disciplineconcerned with the study of the evolutionaryphenomena responsible for the distributionof living organisms in space. I have collectedand analyzed phylogenetic hypotheses anddistributional data for twelve clades of Indo-Western Pacific coral reef organisms, com-prising fishes, mollusks and scleractiniancorals. The analysis indicates that the Indo-nesian region, long thought to be a Acenterof origin@ for most of the Indo-Western Pa-cific marine fauna, seems to be a very de-

rived area, and that most of the lineages mayhave had their origins in the Eastern IndianOcean or in the South-Western Pacific.

P1.14A SARGAZI, M., ROBERTS, N.B.,SHENKIN, A.; The University of Liverpool.Cytotoxic studies of Fe and Zn comparedwith Hg on a monolayer of renal proximaltubular cells (PTC) and the evaluation ofcytoprotectants.

The toxicity effects of iron (III), zinc andHg were evaluated between 0, 25, 50, 75,100 mmol/l final concentrations on PTC in amonolayer culture. Assessment of cell viabil-ity used MTT (Thiazol blue) uptake as anindicator of mitochondrial membrane integ-rity, release of NAG (N-Acetyl-b-D-glucosaminidase) as an indicator of lysoso-mal damage, LDH (lactate dehydrogenase)as an indicator of plasma membrane integ-rity and DAPI staining for DNAfragmentation.Studies showed that Fe andZn reduced cell viability maximally by 40 %and 30 % after 72 and 48 hrs incubation,whereas reduction for Hg was 95 % after 72hrs at the concentration of 100 mmol/l re-spectively. Fe and Zn showed an increase(3.7 % and 11 %) in NAG activity, whereasHg showed an inhibitory effect. All elementsinduced LDH release 2-3 fold. DNA frag-mentation by DAPI staining showed no dif-ference from control for Fe, but there wasobvious nuclei condensation for Zn and Hgexpressing a typical apoptosis model of celldeath.Electron microscopy in treated cellswith Fe showed no changes. However in Hgtreated cells there was loss of brush bor-ders, the presence of vaccuolated cyto-plasm, disruption of mitochondria and lossof nucleus density.Glutathione and Tioproninshowed a significant protective effect on thePTC exposed to Fe, Zn and Hg. Howevervitamin C and cysteine had no effect on cellstreated with Hg. Conclusion: Iron, zinc andmercury showed toxic effect on kidney proxi-mal tubular cells, which include damage toplasma membrane, cytoplasm and/or thenucleus.

18.1 SATTERLIE, R.A.*, NOLEN, T.G., Ari-zona State University, SUNY New Paltz. Thesmall number of swim pacemakers incubomedusae may promote biphasic modu-

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lation of swimming activity.Since the earliest behavioral investiga-

tions of scyphomedusan and cubomedusanswimming, swim contractions were found tobe controlled by multiple pacemaker/sen-sory centers that were spread around themargin of the jellyfish. Coordination of swimpacemakers was presumed to be due to asimple dominance hierarchy, in which a dis-charge in one pacemaker would reset all ofthe other pacemakers. The resultant pace-maker redundancy was examined in threeprevious modeling studies in which contrac-tile activity in a piece of jellyfish containing asingle rhopalium was used to construct mod-els of multiple-pacemaker networks. In allthree studies, pacemakers were connectedto one another with re-setting linkages simi-lar to those described in earlier works. Weconducted a similar study on thecubomedusa Carybdea marsupialis, but ourinitial results are not consistent with a modelin which pacemakers interact via simple re-setting linkages, thus challenging the de-cades-old notion of how pacemakers inter-act in cubozoan and scyphozoan jellyfish.In our study, real electrophysiological datawere compared to resetting and indepen-dent computer model networks of pacemak-ers. The real data fell between that of thetwo models suggesting that pacemakersshow a degree of independence. Our mod-els also suggest that this type of semi-inde-pendent network may allow a greater sensi-tivity to asymmetrical stimuli, and thus allowsignificant directional reponses to thesestimuli.

P2.2 SAVAGE, R.M.*, MEIKLE-JOHN, D.A.,Williams College. Hunchback homologuesin annelids.

We are interested in how body plans arepatterned and have focused on characteriz-ing homologues to the Drosophila gap geneHunchback (hb) in two annelid classes. Thehb gene encodes a C2H2 zinc-finger tran-scription factor that plays a pivotal role in flypattern formation. We are using a cross-spe-cies antibody to compare the expression pat-terns of hunchback-like proteins in bothleeches (Helobdella) and polychaetes (Capi-tella). Hb-like protein is expressed in the mi-

cromeres (and its epithelial derivatives), thegut and the nervous system in both classes,and the class-specific differences in expres-sion correlate with changes in life history.Comparative studies between dipteran in-sects, nematode and annelid hbexpressiondomains suggest there are at least twophases of shared hb function: an embryonicand organogenic phase. In the embryonicphase, hb is expressed in cells undergoingproliferation such as the epithelial cells thatalso undergo morphogenetic movements. Inthe organogenic phase, hb is expressed indifferentiated neurons of the VNC and theperipheral nervous system. Together the hbexpression patterns in annelids and nema-todes suggest that they do not participate inanteroposterior (AP) pattern formation in ananalogous way to that of the hb in flies. Thisspecific function apparently originated withinthe insect lineage. However the data doesnot preclude the possibility that hb homo-logues outside of insects adopted other pat-terning functions. This research is supportedby NIH grant (HD-57778) to RMS.

P3.77SCAPPATICCI, A.A.*, KASS-SIMON,G., University of Rhode Island. Nematocystdischarge: the response of prey capturingdesmonemes to chemical and mechanicalstimulation.

The effects of chemical and mechani-cal stimulation on the discharge ofdesmonemes were quantitatively studied insitu, in ablated tentacles and in hypostome-attached tentacles of Hydra. Feeding andlocomotion in hydra depend upon the dis-charge of nematocysts. Nematocysts arespecialized organelles which possess aprominent trigger hair, the cnidocil. Thereare three types of nematocysts, thestenoteles, which pierce and paralyze prey,desmonemes, which ensnare them, andisorhizas, used for locomotion. Cnidocils ofdesmonemes were stimulated, 4 and 24hours after tentacle ablation, with piezoelec-trically-driven probes vibrating at frequen-cies ranging between 2 and 80 Hz. The ef-fect of a nematocyst sensitizing agent, mu-cin, was studied at 6 and 60 Hz. Withoutmucin, desmonemes discharged in a fre-quency-dependent manner in 24 hour ab-lated tentacles, and in 4 and 24 hour ab-

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lated hypostome-attached tentacles, with op-timal discharge occurring between 15 and35 Hz. The presence of the hypostome sig-nificantly depressed the response by over30%. There was no frequency differentia-tion in 4 hour ablated tentacles. Desmonemedischarge was enhanced by the presenceof mucin in a dose-dependent manner, withoptimal discharge occuring at 1 X 10-11M andcomplete inhibition occurring at 1 X 10-5M.Mucin increased the number ofdesmonemes discharged at 60 Hz to equalthe number discharged at 6 Hz without mu-cin. 6 Hz is the swimming frequency of labo-ratory prey. Striking the cnidocil with singlecontacts of increasingly greater force causeda significant increase in discharge in a dose-dependent manner. Our results suggest thatthe desmonemal cnidocil responds to theimpulsive force of a mechanical stimuluswhose threshold is lowered by the presenceof mucin.

58.4 SCHAACK, S.*, CHAP-MAN, L.J.,University of Florida, Gainesville. Cascad-ing effects of hypoxia on the functional mor-phology, ecology, and diversification of anAfrican cyprinid.

Adaptive change in one character mayaffect associated, but functionally unrelated,characters in an adaptive or non-adaptiveway. For example, in some fish species, in-dividuals living in low oxygen environmentshave larger gills than conspecifics living inwell-oxygenated water. Adaptive change ingill size may alter adjacent feeding struc-tures and therefore have indirect effects onbehavior or other fitness components. Thisstudy investigates whether variation in gillsize of the African cyprinid Barbus neumayericorrelates with variation in associated trophicstructures, foraging ecology and fitness-re-lated characters in two populations living indifferent oxygen regimes. Our different popu-lations of B. neumayeri offer a unique sys-tem to examine functional-morphologicaltradeoffs. Reciprocal transplant cage experi-ments showed lower survivorship for small-gilled fish moved to hypoxic swamp waters.Large-gilled fish, however, do not show lowersurvivorship in stream cages, though theymay suffer a competitive disadvantage if theirlarge gills impact associated feeding struc-

tures. To investigate this question, we com-pared trophic morphology and feeding effi-ciency of fish from small- and large-gilledpopulations. In addition, we evaluated dif-ferences in diet by quantifying prey abun-dance and selection for each group. Finally,we looked at fitness components in naturalpopulations, including growth rates and con-dition factor. Our results demonstrate differ-ences in functional morphology, feeding ef-ficiency, diet, and some fitness componentsbetween the two populations. We argue thatvariation in gill size has facilitated the broadhabitat distribution of B. neumayeri but maylimit the success of phenotypes crossingphysico-chemical gradients leading to diver-sification in this species.

P2.70SCHAUB, M.J.*, ZALISKO, E.J.,SCHAEFER, J.C., Blackburn College. An-other advantage of long sauropod necks:reaching out and over hazardous environ-ments.

Long necks in sauropods may have di-verse advantages. In addition to reachingup to browse on high vegetation, long neckspermit sauropods to graze where they can-not easily stand, pass, or reach. Such re-strictive environments include the marginsand bottoms of aquatic systems. We testedthe forces required to extract limbs from mudto estimate the difficulties encountered by alarge sauropod struggling to move throughsaturated soil. Sauropod leg models con-sisted of PVC pipes (1.6-11.4 cm diameter)with attached end caps. Additional weightwas added inside the tubes as needed toadjust each leg to a standard weight of 2.5kg. Thus the legs varied only in their dimen-sions. Legs were submerged into a tub con-taining saturated potting soil to a depth of 45cm. A pulley system was used to determinethe force required to vertically extract eachlimb in a standard period of time. The resultsindicate that drag force increases at nearlythe same rate as the radius of the leg. Inaddition to requiring greater forces for limbextraction, muddy environments pose otherchallenges. Saturated soils often consist ofa moving, unstable substrate. Extractinglimbs from deep mud likely required a de-gree of agility and flexibility beyond thatfound in large sauropods. Longer necks

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would allow these animals to graze at themargins of aquatic environments that theyotherwise could not reach.

16.4 SCHMIDT, K.E.*, LEAL, R., DESAI, P.,KELLEY, K.M., California State University atLong Beach. Proposed growth-inhibitory roleof a membrane-associated insulin-likegrowth factor-binding protein (IGFBP) in aniguanid heart cell.

A heart cell line derived from Iguanaiguana expresses a single IGFBP that ispresent as both a secreted 30 kDa proteinas well as bound on the cell membranes.Competition binding assays for the solubleiguana IGFBP demonstrate that the proteinbinds 125I-IGF-I in a highly specific manner,with 50% inhibition of 125I-IGF-I binding be-tween 0.1-0.5 ng/ml of added unlabeled IGF-I. Affinity crosslinking of 125I-IGF-I to cell mono-layers demonstrates that this IGFBP is alsobound to the cell membranes at levels thatrival that of the type-I IGF receptor. Additionof excess unlabeled IGF-I at concentrationsabove 10 ng/ml results in the removal ofmembrane-bound IGFBP, upon which a cor-responding increase in its levels in the me-dium are detected. This “membrane-re-moval” effect of IGF-I occurs rapidly, within 5min of peptide addition. When the cells areprecultured for 15 min in medium contain-ing 100 ng/ml IGF-I, followed by replacementof fresh identical medium (i.e., IGFBP is re-moved from membrane and the mediumcontaining released IGFBP discarded), themitogenic effect of IGF-I is significantly en-hanced as compared with cells in which theIGFBP remains throughout. This has pro-moted the hypothesis that this IGFBP servesto inhibit IGF-I actions in the iguana heartcell, using a unique mechanism by whichIGF-I binding to abundant cell membrane-associated IGFBP is followed by release ofthe IGF/IGFBP complex from proximity to thecellular type-I IGF receptor. [Support in partby NSF grant IBN-9600783 & NIH grantGM50089]

S7.3 SCHMIDT-RHAESA, A., UniversitaetBielefeld. The two dimensions of biodiversityresearch exemplified by Nematomorphaand Gastrotricha.

Biodiversity research is characterized by

two dimensions: the horizontal dimensionrecognizes species, their spatial interrela-tionships and patterns such as biogeo-graphical distribution. The vertical dimen-sion tries to explain the history of the recentbiodiversity through phylogenetic and evo-lutionary approaches. The horizontal dimen-sion is illustrated by Nematomorpha (horse-hair worms). The standard of species de-scriptions has to be raised and reinvestiga-tions are necessary, if statements accordingspecies numbers, distribution patterns, im-pact on their host population and the role inthe ecosystem should be substantial. Thevertical dimension is illustrated by gastrot-richs. Recent hypotheses about their place-ment differ, either including them in theSpiralia (molecular data) or placing thembasal to Cycloneuralia/Ecdysozoa (morpho-logical data). In both hypotheses, however,gastrotrichs are a very basal bilaterian taxonand therefore have a potentially solid im-pact on the phylogeny of this taxon as wellas the reconstruction of it’s ancestor.

P1.3 SCHNEIDER, K.S., University ofFlorida. The respiratory ecology of benthicmacroinvertebrates in a swamp-river systemin East Africa.

Hypoxia (oxygen scarcity) is widespreadin tropical freshwater systems, particularlyin dense swamps, and may be an importantfactor structuring benthic macro-invertebratecommunities. Benthic macro-invertebratesshow a broad diversity of respiratory modesranging from atmospheric breathers to tra-cheal gills. These adaptations have associ-ated costs and benefits that vary with eco-logical backgrounds and affect the ability ofaquatic invertebrates to use hypoxic water.The objectives of this study were to (a) de-scribe the benthic macro-invertebrate com-munity from nine sites in Kibale NationalPark, Uganda and (b) determine the degreeto which dissolved oxygen can explain varia-tion in respiratory guilds. There were distinctdifferences among sites in the occurrenceof respiratory guilds and in their relativeabundance. Across all sites, the percent rela-tive abundance of atmospheric breatherswas negatively correlated with concentra-tion of dissolved oxygen, while the relativeabundance of tracheal gill breathers was

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positively correlated with dissolved oxygen.Invertebrates with permanent or temporaryair storage (transportable stores) were onlyfound in high abundance in well-oxygen-ated flowing water. Seasonal differences inthe relative abundance of respiratory guildswere most pronounced in the papyrusswamp site where dry season conditionsproduce extremely hypoxic waters (<1.0 mg/L). In the dry season the swamp was charac-terized by fewer respiratory guilds and ahigher abundance of atmospheric breath-ers than during the wet season. Althoughother environmental characters may influ-ence the composition of benthic macro-in-vertebrates communities, dissolved oxygenconcentration seems to be a good predictorof respiratory guild abundance and a keyfactor in maintaining invertebrate faunalstructure and diversity.

4.1 SCHOENFUSS, H.L.*, BLOB, R.W.,University of Minnesota, St. Paul, Field Mu-seum, Chicago. Kinematics of vertical climb-ing in hawaiian freshwater gobies.

The Hawaiian freshwater ecosystemincludes three species of waterfall climb-ing gobies. Larvae of these species arewashed into the ocean by currents uponhatching, return to freshwater 3 to 6 monthsposthatching, and then climb waterfalls (upto 350 m vertically for Lentipes concolor)to reach adult habitats. We used high-speed video to contrast climbing kinemat-ics of Sicyopterus stimpsoni (20-24 mmtotal length) with that of Awaousguamensis and L. concolor (both 12-16 mmTL) on a clear plexiglas waterfall. L.concolor and A. guamensis climb verticallyusing bursts of axial-based swimming.Bursts typically last 0.07 ± 0.02 sec at ve-locities of 10.3 ± 4.2 TL/sec (190 ± 80 mm/sec). The pectoral fins extend perpendicu-lar to the body during pauses betweenbursts, but adduct quickly as climbing re-sumes (possibly contributing to thrust ini-tiation). In contrast, S. stimpsoni usuallyclimb by alternately attaching oral or pel-vic sucking discs to surfaces and ‘inching’upwards with little axial undulation or finmovement. As the oral disc attaches it ex-pands to twice its resting area, after which

the posterior body is pulled upwards; oncethe pelvic disc attaches, the oral disc re-leases and the anterior body advances.Climbing bouts can include multiple cyclesof disc attachment and last several sec-onds at velocities of 0.25 ± 0.04 TL/sec (6± 1 mm/sec). The use of power-bursts toclimb may be impeded in S. stimpsoni asthis species typically loses 15% of itsweight during metamorphosis precedingtheir migration up waterfalls. By ‘inching’up waterfalls, S. stimpsoni always remainattached to the substrate by suction at leastat one point along the body. ONRN000149910184 (M. Westneat); HawaiiFish Restoration Project F-14-R-18 (M.Fitzsimons).

S5.3 SCHULTZ, J.C., Penn State University.Shared signals and the potential for phylo-genetic espionage between plants and ani-mals.

Our understanding of responses to bioticand abiotic stimuli has developed sepa-rately for plants and animals. But recent bio-chemical and molecular work is producinga growing list of elements involved in diverseresponses that are common to both king-doms. Some of the more interesting ex-amples of these are reviewed, includingprostaglandin/octadecanoid-mediated re-sponses to wounding, oxidative defenses,steroid- and flavonoid-based signalling sys-tems, and pathogen-recognition mecha-nisms. Some of these similarities probablyrepresent evolutionary convergence, whileothers may be ancestral to the developmentof plants and animals. Whatever the origins,they permit widely divergent taxa to exploiteach other’s signalling systems (“phyloge-netic espionage”). The ecological and evo-lutionary consequences, of such overlapsare highlighted. These include the existenceof pathogens that can cause disease inplants and animals (e.g., strains ofPseudomonas aeruginosa), the ability ofherbivores to manipulate plant disease andanti-herbivore responses and enhance plantquality; the usurpation of microbial mecha-nisms and genes by parasitic insects, her-bivorous animals, and plants; the evolutionof plant defenses that exploit signalling sys-

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tems shared by animals; and the medicinaluse of plants by humans. Comparative studyof the signalling and response mechanismsused by plants, animals, and microbes todeal with dynamic environments providesnovel and useful insights to the ecology andevolution of interactions across kingdoms.Some of these insights suggest new waysin which we might exploit plants, animals,and microbes to our own benefit.

7.4 SCHWARTZ, M.L., NOR-ENBURG,J.L., George Washington University, Wash-ington, DC, Smithsonian Institution, Wash-ington, DC. Can we infer heteronemerteanphylogeny from morphological data?

A cladistic analysis of the genera withinthe order Heteronemertea (Nemertea) wasperformed from morphological data gath-ered from the literature. Resulting trees werenumerous and mostly unresolved. Theanalysis gives insight into current taxonomicproblems for the heteronemerteans. Chiefamong these are brief and inadequate taxo-nomic descriptions of species and morpho-logical features. The limited number of char-acters and poor definition of homologiesavailable in this literature-based data setresult in abundant homoplasy and hinderprogress towards building a robust phylog-eny for the Heteronemertea. To remedy this,we are undertaking a critical re-examina-tion of taxa and characters by direct study ofa range of heteronemertean exemplar spe-cies, for which we are gathering molecularsequence data to complement the morpho-logical data. We expect the resulting analy-ses to alter drastically the face ofheteronemertean systematics.

29.4 SCHWARTZ, T.S.*, KARL, S.A., Uni-versity of South Florida, Tampa. Geneticstructure of florida gopher tortoise(Gopherus polyphemus) populations.

Gopher tortoise (Gopherus polyphemus)population sizes are believed to have de-clined by an estimated 80% in the past 100years. Habitat destruction from human de-velopment, predation, and infection fromupper respiratory tract disease (URTD) havecontributed to this decline. We currently areusing 7-10 microsatellite loci to investigat-

ing the genetic structure andphylogeography of 18 gopher tortoise popu-lations throughout Florida. Estimates of in-breeding and migration have been deter-mined for 5 of these populations. Effectivepopulation sizes (Ne) based on microsatellitedata are being correlated with parallel fielddemographic studies. The occurrence ofURTD will be compared to gene flow pat-terns among populations in an attempt toassess the potential association of migra-tion with the spread of the disease.Microsatellite data will be used to evaluatethe phylogeography of the tortoise withinFlorida, and to identify potential effects ofisolation in the populations peripheral to theBrooksville and Lake Wales ridges. This re-search will provide estimates on populationviability and help focus conservation effortson this threatened species.

8.1 SCHWENK, K., University of Con-necticut, Storrs. Extrinsic vs. Intrinsic lingualmuscles: the amniote tongue as a functionalunit.

The muscular tongue of amniote verte-brates is traditionally described as a com-posite of two muscle types: extrinsic musclesoriginate outside the tongue and insert withinit; intrinsic muscles arise and insert com-pletely within the tongue. Whole-tonguemovements are attributed to the former, lin-gual shape change to the latter. This dichoto-mous view of tongue structure and functionhas endured since the mid-19th century, de-spite persistent indications of its inadequacy.A histological analysis of the mm. genioglo-ssus and verticalis in mammals and the m.hyoglossus in lepidosaurian reptiles finds:(1) the “extrinsic” m. genioglossus contrib-utes extensively to the “intrinsic” m. verticalis;(2) the verticalis “muscle” is composed offibers from at least three nominally separatemuscles, both extrinsic and intrinsic (genio-glossus, longitudinalis inferior, intrinsicverticalis fibers); (3) the “extrinsic” m. hyo-glossus in lepidosaurs comprises both ex-trinsic and intrinsic parts which may be his-tochemically differentiated. Current modelsof the tongue as a muscular hydrostat sug-gest that it functions as an integrated func-tional unit and that the traditional atomistic,

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dichotomous view of lingual muscles is in-accurate and misleading. The notion of indi-viduated “muscles” is inapplicable within thetongue and should be replaced by referenceto “fiber systems.” This view of the tonguehighlights the weakness of an atomistic ap-proach to complex form and calls into ques-tion the application of traditional characterconcepts and character analyses to inte-grated functional units.

39.5 SCOTT, M.P., University of New Hamp-shire. Hormonally-mediated cues for materecognition by burying beetles.

Individual recognition of a mate or a pastenemy has seldom been demonstrated ininvertebrates. When recognition cues havebeen identified, they are usually found to bebased on social status or family member-ship. Burying beetles rear a brood on an un-predictable resource and as a pair, they mustdefend their young and the resource fromconspecific intruders. Thus a mechanism forthe identification of a non-mate is necessaryfor the appropriate aggressive response.Burying beetles appear to match the hor-monal state of an intruder to a templatebased on that of their mate. Unknown indi-viduals at the same reproductive stage wereaccepted as mates. In addition, aggressionby males was significantly reduced towardsunknown non-breeding females treated withjuvenile hormone or its analogue,methoprene. When mating behavior was ex-amined, the “acceptance threshold” for thecomparison of the unknown individual to thetemplate was lower than for aggressive be-havior. Males were more likely to mate orattempt to mate with non-breeding, breed-ing, or treated strangers than with their ownmate, as long as trial with the mate precededthe trial with the stranger. Aggression towardunknown non-breeding females treated withan extract of the mate’s cuticular hydrocar-bons was reduced. Thus we conclude thatrecognition cues are provided by contactpheromones.

P1.83SCRUGGS, J.R.*, GLAS, P.S., TheCitadel, Charleston, SC. Protein changes inthe embryonic coat during development ofthe grass shrimp, Palaemonetes pugio.

The morphological changes in the em-bryonic coats of grass shrimp were shownby Glas, et al. (1997), but the composition ofthe embryonic coat has yet to be determined.This study determined that the embryoniccoat protein composition of the developinggrass shrimp changes over time as the em-bryo adds new internal envelopes. Embryoswere collected during each stage of theirembryonic development, and the embryoniccoats were isolated. The isolates were thenelectrophoresed, fixed and stained for pro-tein. Additionally, embryos were cultured incell culture dishes, and the supernatant wasremoved and concentrated. The concentratewas then electrophoresed on a gradient gel,fixed and stained. The results of these ex-periments show a change in the position ofthe protein bands suggesting that the em-bryonic coat protein content changes as en-velopes are added and then dissolved dur-ing embryonic development. There was nodefinitive evidence of an ovoperoxidaseenzyme as found in other invertebrates. Thisstudy begins the determination of the com-position of the different envelopes. This de-termination will be of assistance in culture ofsimilar species that are used as food sources.Embryonic coat composition may also be ofuse in environmental monitoring. This studywas supported by The Citadel DevelopmentFoundation (PSG) and Charleston Scientificand Cultural Education Fund (JRS).

46.4 SEAVER, E.C.*, PAULSON, D.,IRVINE, S.Q., MARTINDALE, M. Q., Univer-sity of Hawaii, Honolulu, HI, University ofHawaii, Yale University, New Haven, Conn.,University of Hawaii. Sequence and devel-opmental expression of the engrailed genein the polychaete Chaetopterus.

The number of times a segmented bodyplan has evolved in the metazoa is a cur-rently debated issue. We are interested inunderstanding whether the annelids andarthropods share a common segmentedancestor and have approached this ques-tion by characterizing the expression pat-tern of the segment polarity gene en-grailed(en) in a basal annelid, the polychaeteChaetopterus. We have isolated a memberof the en class of genes from a Chaetopterus

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cDNA library. Not only does the predictedprotein sequence have an en classhomeobox, but the 1.2 kb cDNA clone alsocontains all domains characteristic of en pro-teins in other taxa. Whole mount in situ hy-bridization reveals that en is expressed incomplex dynamic pattern during larval life,when the adult body plan is formed. The entranscript is expressed in all body regions ofChaetopterus, and is localized exclusivelyto mesodermal tissues and small sets of seg-mentally reiterated cells in the nervous sys-tem. Although expression precedes mor-phological segmentation, en does not ex-hibit a segment polarity pattern of expres-sion in the ectoderm, which is the highly con-served pattern observed in arthropods. Ourresults of the expression of en inChaetopterus do not support the homologyof segmentation between annelids andarthropods.

52.5 SECOR, S.M.*, NAGY, T.R., Universityof Mississippi, University, University of Ala-bama, Birmingham. Postprandial responseof plasma lipids and the hormone leptin inpythons.

With each meal, pythons rapidlyupregulate gut performance and dramaticallyincrease metabolic rate. We suggest onemanner by which pythons fuel these post-prandial responses is to mobilize storedenergy sources, particularly lipids. To evalu-ate the mobilization of lipids with feeding wemeasured plasma levels of triglycerides, freefatty acids, and cholesterol from fasted andfed pythons. Aware that the hormone leptinpossibly mediates fat deposition and me-tabolism, we simultaneously measuredplasma levels of leptin from fasted and fedsnakes. Following the ingestion of mealsequaling 25% of their body mass, pythonssignificantly increased plasma levels of trig-lycerides (by 50-fold), free fatty acids (by50%), and cholesterol (by 80%). Simulta-neously, pythons experienced significantincreases (by 65%) in plasma concentra-tions of leptin. Fasted control snakes(sampled at the same time and in the samefashion as fed snakes) exhibited no signifi-cant changes in plasma lipid or leptin con-centrations. Feeding induces in pythons the

mobilization of lipids which conceivablyserve as the energy source to fuel the costlyupregulation of their guts after feeding.Leptin may function to trigger the release ofthese lipids from fat bodies and to stimulatethe postprandial increase in metabolism.

P2.51SECORD, D.*, RUPP, J., University ofWashington, Tacoma, Point Defiance Zooand Aquarium, Tacoma, WA. Interpretingmarine invasive species for the public: auniversity-aquarium collaboration.

Economic and ecological problems as-sociated with aquatic non-indigenous spe-cies (NIS) are growing nationally and inter-nationally. Many of these species introduc-tions are preventable, and are caused byvectors that an informed public can do some-thing about directly (live bait, aquaculture,and pet industries) or indirectly (by support-ing policy limiting ballast water dispersal ofcoastal organisms). In order to reach thebroadest possible audience with accurate,up-to-date information on the biology, pre-vention, and control of marine NIS, the Uni-versity of Washington-Tacoma (UWT) andthe Point Defiance Zoo and Aquarium(PDZA) in Tacoma, WA are jointly designinga public exhibit on NIS for aquaria through-out the Pacific Northwest. We describe theinvolvement of undergraduate environmen-tal biology students, UWT faculty, PDZA cu-ratorial staff, local, state, and federal agen-cies, the Washington and Oregon Sea GrantPrograms, and Northwest graphic designfirms in this collaborative effort. Undergradu-ate research and internship experiences inscientific documentation, organism hus-bandry, artistic design, and public interpre-tation of science and science policy are atthe heart of this effort. This poster describesboth the content of the proposed exhibit (con-cepts of invasion biology and key live or-ganisms as examples) and the process ofdeveloping the necessary broad-based col-laboration. Key messages of the exhibit in-clude the distinction between native andnon-indigenous organisms, costs and ben-efits of allowing new introductions (passivelyor actively), and lessons from specific casestudies (e.g. zebra mussels, European greencrabs, Chinese mitten crabs, saltmarsh

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cordgrass, and introduced ctenophores andsea squirts).

59.7 SEDLMAYR, J.C.*, WIT-MER, L.M.,Ohio University, Athens, College of Osteo-pathic Medicine, Ohio University. The aviansuborbital air sac and its potential role inbrain cooling in birds and other dinosaurs.

The avian suborbital air sac, a caudaldiverticulum of the antorbital paranasal airsinus, partially encircles the eyeball and in-terleaves between portions of the jaw mus-culature. It is unique in being a paranasalsinus capable of being actively ventilatedlike a bellows pump during abduction andadduction of the mandible. The discovery ofa dense venous plexus surrounding the sub-orbital air sinus suggests a physiological roleas an important contributor to selective braincooling via its drainage into the ophthalmicrete, an arteriovenous countercurrent heatexchanger known to cool the hypothalamus.In addition, the suborbital plexus is poten-tially involved in whole-brain cooling viamultiple routes of drainage, including: (1) theethmoid vein and thus the dorsal sagittal si-nus; (2) drainage through foramina for CN II-VI into the cavernous sinus which surroundsthe hypophysis; and (3) along themaxillomandibular (trigeminal) nerve viadrainage of the ophthalmic rete, into the ros-tral petrosal sinus which is in close contactwith the mesencephalon. These findings mayshed light on dinosaur physiology in thatseveral non-avian theropod dinosaurs pos-sess osteological correlates for the subor-bital air sinus; moreover, many fossilarchosaurs display the bony architecturepermitting the presence of a suborbital di-verticulum of the antorbital air sinus. Thevery large size of the cranial nerve foraminain certain dinosaurs may provide further evi-dence of the brain-cooling properties of thesuborbital air sac and/or other orbital vascu-lar structures.

P2.53SELCER, K.W. *, Duquesne Univer-sity. Field ecology laboratory: what to do ona rainy day.

Field biology laboratories are intendedto provide students with experience at con-ducting experiments under field conditions.However, actual conditions at the scheluled

time of the class may not be suitable or de-sirable for field experiments. Therefore, labo-ratory exercises are needed that allow ex-periments to be conducted under simulatedfield conditions. A terrestrial field biologycourse is offered at Duquesne University inthe Spring semester. The first two months ofthis class correspond with winter weather inPittsburgh and therefore are not always ame-nable to field experiments. I employ a seriesof experiments which can be readily substi-tuted for a field excursion if the weather isnot suitable. These include: mark-recaptureof flour beetles, migration (emigration/immi-gration) of sow bugs, and density and diver-sity of plants determined from line intersectand quadrat studies of artificial aerial maps.These substitute experiments have allowedus to learn the methods and principles offield ecology even under the most harsh con-ditions.

13.3 SELCER, K.W.*, DAY, A.M.,VERBANIC, J.D., Duquesne University.Northern leopard frog (Rana pipiens)vitellogenin: purification, development of animmunoassay, and characterization of in-duction following immersion in diethylstil-bestrol.

In oviparous vertebrates, estrogen stimu-lates the female liver to produce the egg yolkprecursor, vitellogenin. This protein circulatesin the blood, is taken up by oocytes, and iscleaved into egg-yolk proteins. Vitellogeninis now being used as a biomarker for expo-sure of animals to environmental estrogens.Thus, there is a need for assays capable ofmeasuring vitellogenin induction in variousspecies. The purpose of this study was tocharacterize vitellogenin induction in adultmale Rana pipiens after injection with estra-diol-17BETA and after immersion in the po-tent estrogenic compound diethylstilbestrol(DES). Sera from estrogen-treated frogs hadsignificantly elevated total protein levels,compared to control frogs. Denaturing gelelectrophoresis revealed increasedamounts of a large (160 kDa) protein, pre-sumably vitellogenin. The identity of the pu-tative vitellogenin was confirmed by itscross-reactivity in Western blots with an an-tibody generated against a Xenopus laevis

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vitellogenin peptide and by its elution fromDEAE-chromatography under high-salt con-ditions, which is typical of vertebratevitellogenins. An anti-Rana pipiensvitellogenin antibody was also generatedfrom the purified vitellogenin. An enzyme-linked immunosorbent assay was developedfor Rana pipiens vitellogenin and the assaywas used to characterize vitellogenin induc-tion in frogs immersed in DES for varioustimes and at different doses. Elevations inserum and hepatic cytosol vitellogenin weredetected within five days after initial immer-sion in 1 mg/L DES and vitellogenin levelscontinued to increase through 20 days. In-duction of vitellogenin in Rana pipiens maybe a useful model system for field studies ofenvironmental estrogens.

S1.7 SHADLEY, J.R.*, HILL, P.S.M., Univer-sity of Tulsa, OK. Talking back: sending soilvibration signals to lekking prairie molecricket males.

The prairie mole cricket, Gryllotalpa ma-jor, native of the tallgrass prairie of the southcentral U.S., is the largest North Americancricket. A male constructs a specializedacoustic burrow in the spring in the prairiesoil from which he generates an airbornecalling song that attracts flying females formating. At the same time, vibrations with thesame temporal scale and pattern as the air-borne signal are produced in the substratethrough an unknown mechanism. Theseground vibrations can be distinguished frombackground vibrations in the soil with a geo-phone (transducer) buried in the soil at dis-tances up to 3 m, depending on soil condi-tions and conditions that control the back-ground vibration environment (e.g. wind,highway traffic). We hypothesize that malesuse the vibration component of the call asinformation for spacing as they form displayarenas, or leks. We used modified field re-cordings of soil vibrations from singing maleswith an electromechanical vibration exciterto simulate the vibration component of a sing-ing male in playback experiments. Airbornesounds of males were monitored for two min-utes before and two minutes after the intro-duction of the ground vibration signal with atape recorder microphone placed 20 cm from

the burrow opening. Males did respond tothe manipulation experiment; although, weobserved individual variation in the level ofresponse.

P2.67SHADWICK, R.E., SYME, D.A.*,Scripps Inst. of Oceanography, University ofCalifornia, University of Calgary, Alberta. Me-chanical power production by red and whiteswimming muscles of yellowfin tuna(Thunnus albacares).

The mechanical performance of red andwhite muscle from yellowfin tuna was stud-ied in vitro at 25oC using the work loop tech-nique. Fibers from internal red muscle weretaken from two axial locations, 0.5L and0.65L (L=total body length), and subjectedto sinusoidal strains at frequencies of 1-12Hzand activation patterns that mimicked thosein vivo, as determined previously. White fi-bers from 0.45L and 0.65L were tested overfrequencies of 3-15Hz. During steady swim-ming, where the muscle strain cycle (=tailbeat) frequency is 2-4Hz, the activationphase and duration used by fish were nearlyidentical to those that elicited maximal network and power from isolated red muscle.The greatest net work per cycle occurred at1-2Hz, while peak power (=work X fre-quency) was obtained at 3-4Hz. Thus, dur-ing steady swimming the internal red musclefunctions to maximize power production. Athigher frequencies, the stimulation phaseand duration that yielded maximal net workdecreased, as expected, with power drop-ping to zero at about 9Hz. The twitch time(i.e from stimulus to peak force) of red fiberswas about 100ms. Compared to skipjacktuna, yellowfin red muscle has slower con-traction kinetics, so it requires longer andearlier activation to maximize power output.These results are in agreement with the dif-ferences in muscle activation timing previ-ously reported for these two species in vivo.For yellowfin white fibers, tests with optimalactivation produced the greatest work percycle at 8Hz and peak power at 10Hz. Posi-tive net work was still produced at frequen-cies up to 14Hz, approximately the highesttail beat frequency recorded during burstswimming.

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P2.68SHADWICK, R.E.*, STEF-FENSEN,J.F., University of California, San Diego, Uni-versity of Copenhagen. The cost and effi-ciency of aerobic locomotion in the chubmackerel (Scomber japonicus).

The cost of aerobic locomotion in the chubmackerel was investigated at different steadyswimming speeds in a water tunnelrespirometer. Eight fish, 25 to 30 cm in length(L), and 145-199g mass were used at 14-15oC. O2 consumption was measured bycomputer-controlled intermittent flowrespirometry with a ten minute cycle. Fishwere placed in the respirometer and allowedto acclimatize while swimming at a lowspeed (1 L/s) for at least 12 h while O2 con-sumption was monitored. Initially high val-ues typically declined by 3 to 5-fold to a stablelevel after several hours of undisturbed swim-ming. Swim speeds were then raised in in-crements of 0.25L/s each 30 min until steadyswimming was no longer possible, usuallynear 3L/s. A the same time, dorsal body im-ages were recorded by video at 60Hz. O2

consumption increased exponentially withspeed. Extrapolation of ln-linear plots to zerovelocity gave estimates of standard meta-bolic rates (SMR), ranging from 90-120 mgO2/kg/h, or 0.35-0.47 Watts/kg. The aerobicscope was in excess of 6.8 times the SMR.The cost of transport was minimal (2.0-3.5 J/kg/m) at 1.5-1.75 L/s. Kinematic analysis ofthe dorsal body midline, using the Lighthillsmall amplitude bulk momentum model,provided an estimate of the thrust power andkinetic energy losses. By comparing the si-multaneously determined power output andmetabolic power consumed, the froude andaerobic efficiencies were calculated. Thesewere typically >0.8 and <0.2, respectively.

P1.50SHAFER, T.H.*, MON-TOYA, L.M.,HOFFMAN, G.G., University of North Caro-lina, Wilmington. Developmental and envi-ronmental expression of the gene for a Na/K/2Cl cotransporter in the blue crab(Callinectes sapidus).

Juvenile blue crabs (Callinectes sapidus)inhabit low salinity environments (5 ppt orless) in the tidal rivers and creeks of south-eastern NC. Larvae generally hatch fromovigerous females in sea water (about 35ppt). It is possible that an ontogenetic change

in the capacity to osmoregulate dictates thedevelopmental stage at which recruitmentto estuaries occurs. Reverse transcriptase-polymerase chain reaction (RT-PCR) wasemployed to examine the expression ofgenes potentially coding for parts of the os-moregulatory mechanism. A V-type protonpump is expressed at all embryonic and lar-val stages examined. It is also expressed athigh levels in both the anterior (gas ex-change) and posterior (ion transporting) gillsof adult blue crabs. Expression of the V-AT-Pase is equally high in the hepatopancreas.For these reasons, this gene does not ap-pear to be specifically induced as a require-ment for osmoregulation. On the other hand,the mRNA for a Na/K/2Cl cotransportershows interesting tissue-related, stage-re-lated, and salinity-related expression. It ispresent in both gill types but is much morestrongly expressed in the posterior gills. It isabsent in the hepatopancreas. Thecotransporter mRNA is present at high lev-els in all embryonic stages from gastrula tohatching. However, the gene is not ex-pressed in megalopae at 35 ppt salinity. Atthis stage it is induced by gradually decreas-ing the salinity to 5 ppt. This suggests thatthe cotranspor-ter is part of the osmoregula-tory mechanism and that it can be activatedas needed. Zoea stages are being culturedto determine when the cotransporter prod-uct is no longer constitutively present (as inembryos) and when it becomes inducibleby hyposaline conditions (as in megalopae).

47.5 SHAPIRO, M.D., Harvard University,Cambridge, MA. Developmental morphol-ogy and gene expression in lizard digit re-duction

Evolutionary digit loss in lizards. has beenattributed to truncations in ancestral devel-opmental programs, while another hypoth-esis refutes this idea. However, neither hy-pothesis has been tested in a developmen-tal framework. Among living tetrapods, Aus-tralian skinks may offer the best examples ofgraded limb reduction. Within its WesternAustralian species, the genus Hemiergisdisplays a graded morphocline of digit con-figurations, containing from 2 to 5 fully formeddigits, on both sets of limbs. Growth series of

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embryos from taxa with different adult limbconfigurations were cleared and stained toelucidate comparative ontogenetic patternsof the limb skeleton. Digit loss among thesetaxa did not result from the truncation of anancestral limb development program, whichwould have yielded only partial digits, butrather from localized differences in limb mor-phogenesis. Moreover, immunohistochemi-cal studies suggest that differential tempo-ral expression of the anteroposterior pattern-ing gene Sonic hedgehog may play a rolein digit loss in Hemiergis, but do not impli-cate other proteins as regulators of digit lossin these lizards.

P2.7 SHARDO, J.D.*, GRANDE, T., Univer-sity of South Alabama, Mobile, Loyola Uni-versity Chicago, Illinois. Morphology and de-velopment of the postcranial axial skeletonof the American shad, Alosa sapidissima.

The morphology and ontogeny of thepostcranial skeleton were studied in threedevelopmental series and a number ofpostmeta-morphic specimens of Americanshad, equaling more than 180 specimens.Specimens were cleared and stained withalcian blue to identify cartilage structures andwith alizarin red to examine bone develop-ment. Histological preparations were madeto confirm several questionable cases ofendochondrial ossification. Pre-hatch em-bryos lack postcranial skeletal elements al-though the finfolds and pectoral fin buds arepresent. By the end of the yolk-sac larvalperiod the hypurals in the caudal fin beginto form, rapidly followed by the developmentof the dorsal and anal fins. As the medialfins form, the elements of the vertebral col-umn develop. The paired pelvic fins are thelast to form during the metamorphic changeof larvae into juveniles. The developmentalsequence was divided into a series of stagesthat will allow future comparisons with otherclosely related species. Our results alsoshow that 1) the uroneurals in shad areendochondrial in origin like other teleosts,2) hypural 1 is autogenous because of in-complete ossification, 3) mineralization ofprotocentra occurs in an anterior to poste-rior direction resulting in chordacentra, and

4) development of the skull and anterior ver-tebral column exhibit several modificationsassociated with the otophysic system andsound transmission.

P2.96SHEETS, D.H.*, ZELDITCH, M.L.,Canisius College, University of Michigan.Studies of shapes with bilateral symmetry.

The first step in any comparison ofshapes is putting them in a common frame-work or registration, which is done by super-imposition. Superimposition involves plac-ing shapes on top of each other, mathemati-cally rescaling them, and sometimes rotat-ing them so that they differ as little as pos-sible from each other. This allows for math-ematical comparison of shape, eliminatingdifferences in size or position of the object.The most common methods of superposi-tion are based on minimizing the morpho-metric difference between two shapes. Weshow how these approaches can producebiologically unreasonable superpositionswhen organisms are bilaterally symmetric.The problem is that the methods do not re-spect that axis of symmetry. We suggest analternative approach to superimposition thatdoes respect axes of symmetry. This alter-native is likely to be most useful in cases ofbilateral symmetry, but may also be usefulwhenever workers wish to prevent biologi-cally implausible rotations of shapes. Soft-ware developed for several superpositionmethods will be shown and made available.

31.2 SHEIL, C.S., University of Kansas,Lawrence. Amniote phylogeny inferred frommorphology.

Phylogenetic relationships among livingand fossil amniotes remain uncertain, andthe topic is among the most contentious inevolutionary biology. Numerous evolution-ary hypotheses supported by molecular andmorphological data have been published re-cently. Previously, I presented results of acollaboration that combined the largest setof morphological and molecular data. Here,preliminary results of an expanded morpho-logical data set (i.e., incresed taxon and char-acter sampling) are presented. Extant taxarepresent six amniote lineages (birds, croco-dilians, mammals, rhynchocephalians,

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squamates, and turtles). Extinct taxa repre-sent several fossil lineages: Captorhinidae,Procolophinidae and Pareiasauridae (non-turtle anapsids); Petrolacosaurus andAraeoscelis (early diapsids); Mesosauridae;and several non-mammal synapsids. Addi-tional taxa and characters will be added.Relative congruence among alternate phy-logenetic hypotheses, taxon and charactersampling, and missing data will be dis-cussed.

P3.82SHERMAN, M.L.*, MOORE, P.A., Bowl-ing Green State University. Boundary-layereffect on the chemical signal movementalong the body of the brown bullhead.

Flow speed influences the spatial andtemporal distribution of a chemical signal.However, a boundary layer exists aroundthe olfactory appendages and can furtherinfluence the distribution of chemical signal.The goal of this research is to quantify howmorphology and fluid flow interact to influ-ence the movement of a chemical signalalong an organismís body. This research iscritical for understanding the interaction be-tween hydrodynamics and sensory biology.Brown bullheads have taste buds along theirbody that are used to sense chemicals thatmediate a variety of behaviors. The chemi-cal signal was measured using the IVEC 10along the body of a model brown bullhead.Several parameters, including peak length,peak rise time, maximum height, absoluteslope, and maximum slope were analyzedas well as a spectral analysis. Differences insignal parameters were found along thebody and at different flows. These resultsshow that the presence of the model, flowand position on the fish model affects thechemical signal properties and thus influ-ences the type of information the bullheadcan perceive. There is an interaction occur-ring between flow, the presence of modeland specific areas on the fish. This indicatesthat the morphology of the body affects sig-nals attributes and acts as a sensory filter.

P2.86SHERMAN, R.L.*, SULIKOWSKI, J.,SPIELER, R.E.; Nova Southeastern Univer-sity, University of New Hampshire, NovaSoutheastern University Oceanographic

Center and Guy Harvey Research Institute.Similarities and differences in fine gill vas-culature among batiod elasmobranchs.

Classic studies of gill vasculature indi-cate the gross anatomy of elasmobranchgills is similar in most species, and in gen-eral, resembles that of teleosts. Recentstudies of fine gill structure of several spe-cies of batoid elasmobranchs (Order:Rajiformes), however, have reported pre-viously undescribed fine structural differ-ences including; the presence, inUrolophus jamaicensis, U. mucosus, U.paucimaculatus, Rhinoptera bonasus,Dasyatis americana and D. sabina (Sub-order: Myliobatoidei), of; 1) a tip channel,possibly an extension of the afferent fila-ment artery that runs along the distal endof the filament corpus cavernosum; and 2)a vascular arcade, a vessel serially con-necting afferent filament arteries of indi-vidual hemibranchs near the tip of the gillfilaments. Using light and scanning elec-tron microscopy we examined the fine gillstructure of Raja erinacea, R. ocellata andR. radiata (Suborder: Rajoidei). Contraryto previous reports which suggested thatthese structures might be unique toMyliobatids, results of this study indicatethe presence of a similar vascular arcadeand tip channel in Rajoidei. However, dif-ferences were found in the gross structureof the ventral aorta and afferent branchialarteries between the suborders. Additionalresearch is necessary to further elucidatethe adaptive significance, if any, of thesemorphological differences betweenclosely related groups of Rajiform fishes.

25.3 SHERRARD, K.M., University of Chi-cago. Limits to early juvenile suspensionfeeding performance in sea squirts.

Post-metamorphic marine invertebratesare maximally different from adults in size,though often similar to them in morphologyand behavior. How does small size affectearly juvenile performance? Ascidians, assessile suspension feeders, provide a con-venient system in which to investigate thisquestion. In the first weeks of juvenile exist-ence there are a number of morphologicalchanges which potentially influence suspen-

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sion feeding performance: the siphons ex-pand and rotate to an upright position, theciliated stigmata lenghten and multiply, andthe animal grows away from boundary lay-ers near the substrate. In the solitary spe-cies Corella inflata, individuals increasegreatly in size, from a siphonal Reynoldsnumber of 10-2 to 102. In the colonial speciesDistaplia occidentalis, the first zooid doublesin length during the first two weeks, afterwhich additional zooids begin to appear.High resolution, in vivo particle tracking ex-periments using early juvniles of these twospecies suggest that the high cost of resis-tance to flow in a small siphon is balancedby its greater ability to draw in particles.

S14.1SHI, Y.B.; NICHD. Mechanism and de-velopmental function of gene regulation bythyroid hormone receptors in Xenopuslaevis.

Thyroid hormone (T3) receptors (TRs)are the presumed mediators of the effects ofT3 during metamorphosis. Interestingly,these receptors are expressed not only dur-ing metamorphosis but also in premetamor-phic tadpoles when there is no T3. To inves-tigate the roles of TRs during Xenopus laevisdevelopment, we have taken several ap-proaches. First, using an oocyte transcrip-tion system, we have demonstrated that TR/RXR hetero-dimers can alternatively activateor repress a T3-dependent promoter in chro-matin in the presence or absence of T3, re-spectively. Furthermore, transcriptional regu-lation by TR/RXR appears to involve histoneacetylases/deacetylases and transcriptionalactivation is accompanied by drastic chro-matin disruption. Second, we have analyzedthe expression of TR and RXR (9-cis retinoicacid receptor, the hetero-dimerization part-ner of TR) genes during development, whichsuggests that TR/RXR heterodimers havedual roles during frog development. Third,by introducing TRs and/or RXRs into Xeno-pus embryos, We have shown that TR/RXRheterodimers, but not TRs or RXRs alone,can precociously activate endogenousgenes in the presence of T3, while repress-ing these genes in the absence of T3.Finally, we demonstrate by chromatin immu-noprecipitation (ChIP) assay that TR/RXR

heterodimers are bound to T3 target genesin premetamorphic tadpoles. We furthershow that histone acetylation changes cor-relate with T3 target gene expression in somebut not all tadpole organs. These resultssuggest that TR/RXR heterodimers havedual functions during frog development, inpart by modifying histone acetylation.

11.6 SHILLINGTON, C., Oklahoma StateUniversity. Energy metabolism and thermalecology of male tarantulas (Araneae:Theraphosidae).

Male tarantulas of North America engagein intense mate-searching activity during themating season. They compete for opportu-nities to mate and their mating success de-pends largely on rapid walking. Becausethey are ectotherms, their biological pro-cesses are dependent on environmentaltemperatures, which influences body tem-perature (Tb). Tb, in turn, has pronouncedeffects on metabolic rates and activities likelocomotion and may directly influence mat-ing opportunities. Temperature and ener-getic considerations are of particular inter-est because these factors help define thebehavioral capabilities of animals and influ-ence and organism’s interactions with its bi-otic and abiotic environment. Field studiesof active male tarantulas indicate that theyare primarily thermoconform-ers and restrictactivity periods to times when ambient andground temperatures are within their pre-ferred range of body temperatures. Becauseof exceedingly hot day-time temperatures,males retreat below ground into abandonedburrows or holes during daylight hours andemerge around sunset. Times of retreat andemergence are temperature dependent al-though light intensity is also an importantfactor. Resting metabolic rates measured inboth male and female tarantulas increasedwith temperature and, after adjusting for bodymass, males had significantly higher meta-bolic rates than females between 20 and 35degrees Celsius.

S7.4 SHIRLEY,T.C., University of AlaskaFairbanks. Priapulida.

Priapulida are a monophyletic group ofmarine, benthic worms with a retractile in-trovert for locomotion and feeding and a chiti-

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nous cuticle which is shed periodically. Amixture of bilateral and radial symmetry ispresent. The integument may bear manyunique structures, including scalids, flosculi,setae, hooks, trunk scalids, tubercles andtumuli. A spacious body cavity serves as ahydrostatic skeleton and contains a complexalimentary canal with a thick, muscular phar-ynx. Several blood cell types occur. Unusualprotonephridia serve as excretory organs.Priapulids are dioecious, with internal orexternal fertilization; hermaphroditism andparthenogenesis may occur. Indirect devel-opment of demersal larvae is normal, butdirect development occurs in one species.Morphology of larvae is less variable than inadults and three types of larvae are known.Distribution of 18 extant species is from theshallow arctic, to the deep ocean, to intersti-tial waters of tropical, sandy beaches. Sizesvary from meiofaunal (<0.5 mm) tomacrofaunal (40 cm). Some extant speciesare morphologically similar to mid-Cambrianfossils. The feeding ecology of most speciesis unknown, but several macrofaunalpriapulids are predaceous and help struc-ture benthic communities; some are com-mon prey items for marine mammals andfish. Some species have high tolerance ofhypoxic conditions and hydrogen sulfide.Priapulida have close affinities withKinorhyncha, Loricifera and perhapsNematomorpha.

P1.71SHREVE, S.M.*, KELTY, J.D, LEE,R.E., Miami University, University of Chicago,Miami Uviversity. The preservation of repro-ductive behaviors during chilling by a rapidcold-hardening process in Drosophilamelanogaster.

Rapid cold-hardening, which occurswithin minutes or hours, confers protectionfrom injury during sudden chilling. Recently,we demonstrated that rapid cold-hardeningoccurs during ecologically-basedthermoperiods and functions to decrease thetemperature at which flies enter cold torpor.However, the evolutionary significance of thisprocess, as it relates to reproduction, hasbeen little studied. In this study, we demon-strated that rapid cold-hardening preservesnormal reproductive behaviors in the fruitfly, Drosophila melanogaster. Once group

of flies was rapidly cold-hardened by steptransfer of the flies from 23oC to 16oC. Wevideo taped pairs of rapidly cold hardened(RCH) flies (exposed to 16oC for 2 h) andpairs of control flies (transferred directly from23oC) at 16oC, and measured whether theycourted, the duration of courtship, andwhether they mated. More RCH pairs thancontrol pairs were able to court (17 vs. 11pairs) and to mate (11 vs. 0 pairs). The court-ship events of the RCH flies averaged19.0±3.5 min, which was significantly longerthan that of control pairs (9.5±2.2 min). Wealso repeated these tests at 23ƒC and foundno significant difference between RCH andcontrol groups in the number of pairs court-ing or mating. However, the event durationsof the control flies (7.9±1.2 min) were signifi-cantly longer than those of the RCH pairs(4.9±0.7 min).

S10.12 SIMMS, E., BEVER, J. D.; Univer-sity of California, Berkeley. Effects of le-gume symbiosis on rhizobium evolution

Symbiosis between legumes and nitro-gen-fixing bacteria is thought to bring mu-tual benefit to each participant. However, itis unclear how rhizobia benefit from nodula-tion of legume hosts because they fix nitro-gen only after differentiating into bacteroids,terminally differentiated cells that cannot re-produce. Because free-living rhizobia canreproduce, and may benefit from the in-crease of plant root exudates stimulated bynodulation. Hence, evolution of symbioticnitrogen fixation may depend upon kin se-lection. Spatial genetic structure often im-poses constraints on the evolution of kinselected traits because it can influence theirvulnerability to cheating. We have been us-ing simple mathematical models to investi-gate the effect of spatial structure of rhizo-bium populations within the soil on the evo-lution of symbiotic traits. Our models predictthat nitrogen fixation can evolve as a symbi-otic trait under relatively strict conditions ofspatial structure. However, other traits, suchas the ability to produce and use private car-bon sources, may expand the conditionsunder which nitrogen fixation can evolve. Wepresent these and other models that explorethe effect of legume symbiosis on evolutionin this interesting group of bacteria.

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P3.54SIMON WESTENDORF, S.*, PALMER,B.D., Ohio University, Athens, University ofKentucky, Lexington. Seasonal pattern ofplasma steroid levels and ovarian growth inthe adult female slider turtle, Trachemysscripta scripta.

The female seasonal reproductive cyclewas studied in a captive South Carolinapopulation of slider turtles (Trachemys scriptascripta) over a period of one year. Plasmaconcentrations of estradiol-17BETA, proges-terone and testosterone were measuredduring the cycle using radioimmunoassay.Ovaries were removed from randomly se-lected individuals throughout the year tomonitor ovarian growth. While mean ova-rian mass increased from mid-summerthrough the following spring, the increasewas not statistically significant. Mean plasmalevels of all three hormones were relativelylow throughout the year when compared toother freshwater turtle species. Estradiol lev-els were lowest, followed by testosteroneand progesterone levels respectively. Cir-culating estradiol and testosterone levelsexhibited no apparent pattern over the re-productive cycle. However progesteroneconcentrations, although relatively low andstatic during most of the year, displayed adistinct peak, possibly representing a spike,around ovulation. The periovulatory releaseof high levels of progesterone along withthe short life of corpora lutea in these turtles,suggests that preovulatory follicles, ratherthan corpora lutea, may be the primarysource of progesterone in slider turtles.

P1.13SKAGGS, H.S.*, SNYDER, E., HENRY,R.P., Auburn University, Brown University, Au-burn University. Heavy metal effects on car-bonic anhydrase in Callinectes sapidus andCarcinus maenas.

Branchial carbonic anhydrase (CA) ineuryhaline crustaceans is known to functionin active ion uptake and osmoregulation inlow salinity. This function could be compro-mised by heavy metals in the aquatic envi-ronment. Cytoplasmic CA from gills ofCallinectes sapidus and Carcinus maenaswas titrated against increasing concentra-tions of Ag, Cu, Cd, and Zn in vitro to deter-mine the inhibitory effects on the enzyme.

All metals were strong inhibitors of CA fromC. sapidus, with Ki values of 0.39, 0.40, 0.65and 3.88 nM, respectively. Concentrationsneeded to affect 100% inhibition were alsolow: 3.3, 17, 17, and 166 nM, for Ag, Cu, Cd,and Zn, respectively. In contrast, cytoplas-mic CA from gills of C. maenas was muchless sensitive to heavy metal inhibition. Con-centrations of Cu, Cd, and Zn needed toachieve 100% inhibition in vitro were 4.2,5.0, and 12.5 M, respectively, approximately100 to 1000 fold higher than those for C.sapidus. This suggests the presence of ametal-resistant isoform in the gills of C.maenas that may help protect the ion trans-port mechanism against heavy metal toxic-ity. When individuals of C. maenas accli-mated to 35 ppt salinity and exposed to threeconcentrations of Cd (0.1, 1.0, and 10 M)were transferred to low salinity (10 ppt), mor-tality was no different than in control, un-treated crabs. Furthermore, hemolymphosmotic concentrations in both control andtreated crabs stabilized by 12 hr post-trans-fer at between 650 and 700 mOsm.

P2.80SKENE, J.A.*, FISCHER, I.M.,HUBER, M.H., HEDRICK, T., STOCKWELL,E.S., SWARTZ, S.M., Brown University, Provi-dence, RI, Brown University, Providence, RI,Brown University, Providence, RI, HarvardUniversity, Cambridge, MA, Brown Univer-sity, Providence, RI and Dalhousie Uni,Brown University, Providence, RI. Three-di-mensional kinematics of level flight in theEgyptian fruit bat, Rousettus aegyptiacus.

To understand the functional and evolu-tionary significance of the diversity of batwing morphologies, it is critical to understandthe three-dimensional deployment of thewing during flight behaviors. Here, we usethree-dimensional kinematic analysis to in-vestigate wing motion patterns in a medium-sized megachiropteran bat, Rousettusaegyptiacus. We trained four individuals tofly in a wind-tunnel over a range of veloci-ties. We then employed a dual camera sys-tem to record digital video images of flights.From these data we map the three-dimen-sional movement patterns of the shoulder,elbow, carpus, and third and fifth digits. Wedocument previously unde-scribed move-ments of the clavicle and handwing, and find

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significant changes in kinematic patternswith changing velocity. We also use the ki-nematic patterns described here as input intoa computer model of bat flight, and compareresults from this species to previous analy-ses of a much larger megachiropteran spe-cies, Pteropus poliocephalus.

17.4 SMALLWOOD, P.D.*, TERZAGHI,W.B., STEELE, M.A., CARLSON, J.E., MANK,J.E, University of Richmond, Wilkes Univer-sity, Wilkes University, Pennsylvania StateUniversity, Pennsylvania State University.Further investigations into the interactionsbetween small vertebrates and oaks: an in-terdisciplinary approach.

At last year’s meeting, we reported thatseveral species of small vertebrates consis-tently cache viable acorns of the red oakgroup much more frequently than those ofthe white oak group. We hypothesized thatthis behavior affects the structure of forests.Seedlings from red oak species should bewidely dispersed from their parent trees,while those from white oaks should beclumped near the parent tree. We have nowbegun a long term project, utilizing molecu-lar genetic techniques (DNA fingerprinting)to test this hypothesis directly. Here, wepresent an interim report on this project. Wehave mapped study sites in two locations,with some species in common between thesites. We have sampled over 500 adult andseedling oak trees at each site. For one site,we have isolated usable DNA from most in-dividuals. We are now using these DNAsamples to test primer pairs shown to am-plify polymorphic simple tandem repeats(STRs) in other oak species, and to optimizePCR conditions for each primer set. We haveidentified 9 primer pairs which reliably am-plify STRs with multiple alleles (determinedby sizing on agarose and acrylamide gels)in Quercus alba, Q. velutina and Q. rubra.The variation at these 9 sites should allowus to assemble unique profiles for each in-dividual. We are now matching the DNAprofiles of seedlings and adult trees to iden-tify parent-offspring pairs. This allows us todirectly test our hypothesis, by measuringdispersal distances between adult trees andtheir offspring. As far as we know, this repre-

sents the first use of molecular genetic tech-niques to test specific seed dispersal hypoth-eses. NSF-DBI #997 8807

44.3 SMITH, M.H., WILLIAMS, N.L.,STELLWAG, E.J., SCEMAMA, J.L.*, EastCarolina University. Characterization of anovel Hox group gene 1 from Moronesaxatilis.

Hox genes are transcription factors thatcontrol regional specification of tissues indeveloping embryos. Our laboratory is work-ing toward the complete characterization ofthe Hox cluster genes from Morone saxitilis,a member of the order Perciformes. A ge-nomic clone, 11D, was isolated and found tocontain a complete paralogous group 1gene (11D-1). Phylogenetic analysis showsthat 11D-1 is most related to Oryzias latipesand Danio rerio Hox-b1b. Whole-mount insitu hybridization of Morone embryos withan 11D-1 exon1-specific antisenseriboprobe shows an expression pattern dif-ferent from the patterns described for Hox-a1a and b1a genes in Danio rerio. Thesegenes in Danio rerio are expressed prima-rily in the notochord and rhombomeres. 11D-1 is initially expressed in the cell cap duringgastrulation, and in the notochord andparaxial mesoderm during neurulation. Thisearly expression fades and by the 14-somitestage, 11D-1 is later expressed dorso-ven-trally and in the hindbrain before all expres-sion terminates by 72 hpf (corresponding tothe pec fin stage in Danio rerio). The threephase expression, primarily outside of thehindbrain, and the duration of expressionare unusual for a paralogous group 1 gene,and suggests that 11D-1 is a gene not previ-ously characterized in teleosts. However,our data indicates that 11D-1 is a member ofparalogous group 1 and is most likely a B orD cluster derivative. Additional linkage datawill be required to assign 11D-1 to a specificHox cluster.

P2.36SMITH, T.L.*, KARDONG, K.V., Wash-ington State University, Pullman. Cues usedduring post-strike trailing in rattlesnakes.

Research on snake predatory behaviorhas involved identifying the specific cueseliciting foraging and attack behaviors. Prey

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integument and feces have been shown toproduce behaviors correlated with increasedpredatory behavior. In addition, recent stud-ies have shown that blood, itself, providessimilar cues in some groups of snakes. Ithas been proposed that blood acquired dur-ing a predatory strike in rattlesnakes mightelicit elevated levels of tongue-flicking.Rattlesnakes typically release rodents im-mediately poststrike, and exhibit a high rateof tongue flicking along with increased move-ment. Collectively these behaviors havebeen defined as strike-induced chemosen-sory searching (SICS). The strike releasesSICS, and it releases specific poststrike trail-ing of the envenomated rodent. The exactcue (or cues) used during poststrike trailingis unknown, but integumentary cues (mouseodor) are likely used to locate and follow thetrail of the envenomated rodent. Becauseblood has been shown to elicit SICS, weasked if blood might also serve as achemosensory cue guiding post-strike trail-ing as well. In other words, can rattlesnakes(Crotalus viridis oreganus) use blood, alone,as a prey odor trail during poststrike trail-ing? Fifteen snakes were run in a series ofY-maze choice trials, presenting them withblood from the mouse they just envenomatedversus a control trail. We found that althoughthe group of snakes showed an elevatedrate of tongue-flicking, poststrike, they failedto follow a blood trail alone. Therefore, al-though blood seems to elicit SICS, it is not achemosensory cue used directly in poststriketrailing.

6.4 SMITH, W.L., WEBB, J.F.*, VillanovaUniversity. Phylogenetic variation in the mor-phology of the laterophysic connection inbutterfly-fishes of the genus Chaetodon.

The laterophysic connection is a uniquelinkage between paired anterior diverticula(horns) of the swimbladder and mesial open-ings in the cranial lateral-line canals in thesupracleithra, which may allow the lateral-line system of butterfly-fishes in the genusChaetodon to detect pressure stimuli. A his-tological examination of 19 species in 10 ofthe 12 Chaetodon subgenera has revealedtwo laterophysic connection types (directand indirect) and six laterophysic connec-

tion variants on these two types. A directlaterophysic connection (whereswimbladder horns lie deep to the lateral-line canal in the supra-cleithrum with only orwithout intervening mucoid connective tis-sue) was found in 9 species in 6 subgenera.Two variants on the direct laterophysic con-nection differed in the presence or absenceof the mucoid connective tissue and inswimbladder morphology. An indirectlaterophysic connection (where epaxialmuscle lies between the lateral-line canal inthe supra-cleithrum and the swimbladderhorns) was found in 10 species in 5 subgen-era. Four variants on the indirect laterophysicconnection also differed in the presence orabsence of mucoid connective tissue and inswimbladder morphology. We hypothesizethat the variation in soft tissue morphologythat defines the laterophysic connectiontypes and variants is functionally significant.In addition, we used four characters derivedfrom this study to hypothesize newsubgeneric relationships for Chaetodon andto examine the phylogenetic distribution ofthese laterophysic connection charactersamong species in the genus. Supported byNSF IBN-9603896 to J.F.W.

66.1 SNYDER, M.J.*, ROSSI, S., Universityof California, Davis, Institut de Ciëncies delMar, Barcelona, Spain. Alterations in stressproteins correlate with space competition insessile marine invertebrates.

Competition for space among sessilemarine invertebrates, following larval settle-ment, can involve aggressive behaviors andthe production of biologically active sub-stances. These strategies have been widelystudied in benthic cnidarians, for which thedestructive nature of such responses to com-peting species is well known. In this work,we have chosen two nearshore subtidalcnidarians, the anemone Anthopleuraelegantissima and the corallimorpharianCorynactis californica. We tested whetherstress proteins (HSP70) could be useful in-dicators of intra- and interspecies competi-tion intensity in these species. In A.elegantissima, HSP70 was concentrated inthe tentacles while in C. californica, therewas no difference between tentacles and

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body. HSP70 levels were similar betweenC. californica inside and outside polyps whendifferent clones interact, and were fairly con-stant in the coral-limorpharian in the differ-ent interspecies encounters. All C. californicaindividuals appear prepared to war as ex-hibited the high constant polyp HSP70 ex-pression. When interacting with other clonesor specific competitors, A. elegantissimaoutside polyps (warriors) express signifi-cantly higher HSP70 levels than interior pol-yps. A. elegantissima distributes the defen-sive efforts with high warrior tentacle HSP70levels correlating with the clonal responsi-bility for interactions against many differentsessile competitors. Our results demonstratethat biochemical measurements such asstress protein levels may provide interest-ing clues about the in situ intensity and de-structive nature of interactions betweensessile benthic marine species. (Funded byNOAA California Sea Grant R/A-108)

S10.16 SORENSON, M.D.*, PAYNE, R.B.,Boston University, Massachusetts, Univer-sity of Michigan, Ann Arbor. Molecular ge-netic perspectives on the coevolution ofavian brood parasites and their hosts.

Some of the clearest examples of coevo-lution are provided by avian brood parasitesand their hosts. Adaptations of parasitic spe-cies to secure parental care from hosts andcounter-adaptations of hosts to avoid or re-duce the negative effects of parasitism havebeen studied extensively in selected spe-cies. Recently, molecular genetic data haveadded a historical perspective to analysesof host-parasite coevolution. We review re-cent molecular studies on cowbirds, cuck-oos, and parasitic finches, focussing on therole of varying behavioral mechanisms inthe evolution of host-specificity. The Africanindigobirds (Vidua spp.) are the most host-specific of brood parasites. Each indigobirdspecies generally mimics the songs andnestling mouth markings of a single hostspecies. Behavioral studies have demon-strated that indigobirds imprint on the songsof their hosts and that indigobirds reared bya particular host species mate assortatively.Broad sharing of mitochondrial haplotypesand microsatellite alleles among indigobird

species indicates a very recent and rapiddiversification, precipitated by indigobirdscolonizing and imprinting on new hosts.Common cuckoos (Cuculus canorus) areknown for their species-specific mimicry ofhost egg markings. In contrast to indigobirds,different females within this single speciesspecialize on different hosts. The pattern ofmitochondrial differentiation among cuckoofemales using different hosts species is simi-lar to that observed among indigobird spe-cies and supports the long-standing hypoth-esis that cuckoos are divided into distincthost races or “gentes.” In contrast toindigobirds, however, host-specializationhas not lead to speciation because malecuckoos mate with females irrespective ofthe host species that reared them.

P3.42SOTO, N.E.*, MARSHALL, C.,CHENG, C.-H.C., University of Illinois, Ur-bana-Champaign, University of Otago, NewZealand, University of Illinois, Urbana-Champaign. The trypsinogen-like proteaseancestor of the antarctic notothenioid anti-freeze glycogen is a novel serine protease.

Dominating the Southern Ocean fishfauna is a single suborder of perciform te-leost, the notothenioids, which produce an-tifreeze glycoproteins (AFGPs) to survive theice-laden freezing Antarctic water. The an-cestral gene that gave rise to the AFGP genewas that of a trypsinogen-like protease (TLP),but whether TLP is the trypsinogen that per-forms digestive function in the notothenioidsis not known. We have now cloned and se-quenced full length cDNA of both pancre-atic TLPs and digestive trypsinogens acrossnotothenioid families, thereby establishingthat they are two distinct groups of pancre-atic proteases. TLPs are found in allnotothenioids (and non-notothenioids) ex-amined, and they share only ~50% aminoacid identity with digestive trypsinogens inthe respective species. And while TLPs con-tain the conserved catalytic triad, disulfidebridges, and many of the conserved resi-dues, other amino acid differences as wellas structural disparity from digestive trypsi-nogens based on molecular modeling indi-cate the likelihood of a non-trypsin specific-ity. Phylogenetic analyses also reveal sepa-rate grouping of digestive trypsinogens, TLPs

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and other serine proteases. Therefore webelieve TLP is a novel member of the serineprotease family whose precise function re-mains to be ascertained.

P1.41SPANINGS-PIERROT, C.,WEIHRAUCH, D.*, LIGNOT, J.-H.,CHARMANTIER, G., TOWLE, D.W., Univer-sity Montpellier II, France, Lake Forest Col-lege, IL and Mt. Desert Island Biol.Immunolocaliza-tion and gene expressionof Na,K-ATPase in gills of the grapsid crabPachygrapsus marmoratus.

The activity, immunolocalization, andmRNA expression of Na,K-ATPase werestudied in gil ls of the hyper-/hypoosmoregulating crab Pachygrapsusmarmoratus acclimated to salinities of 10,37, and 45 ppt. Enzyme activity was sig-nificantly higher in pooled posterior gills(7-9) than in anterior gills (1-6) and in-creased significantly upon acclimation todiluted medium, confirming previous ob-servations with other crab species. Immu-nofluorescent analysis of gill sections in-dicated localization of Na,K-ATPase pro-tein in basolateral membranes of branchialepithelium adjacent to the afferent bloodvessel. Using degenerate primers basedon Na,K-ATPase ALPHA subunit homolo-gies published in GenBank, we amplifiedrelated sequences in cDNA transcribedfrom gill mRNA and employed the result-ing PCR products for sequencing andmRNA expression analyses. Immunofluo-rescence and mRNA quantitation pro-duced parallel results, showing high ex-pression of Na,K-ATPase protein andmRNA in gills 6, 7, and 8 at low salinity. Ingills 6 and 8, the abundance of Na,K-AT-Pase protein and mRNA increased dra-matically with decreasing salinity. How-ever, gill 7 showed substantial levels ofNa,K-ATPase protein and mRNA even in45 ppt seawater, suggesting that this gillmay play an important role inhypoosmoregulation. Our results offer amolecular explanation for the previouslyobserved changes in Na,K-ATPase activ-ity in gills of euryhaline crabs adjusting toosmoregulatory demands in salinity ex-tremes, namely the upregulation of Na,K-ATPase gene transcription and subse-

quent translation of Na,K-ATPase protein.Supported by NSF (IBN-9807539).

38.2 SPARKES, T.C.*, YAN, H.Y., PRATER,C., AKAMATSU, T, DePaul University, Chi-cago, University of Kentucky, Lexington,University of Kentucky, Lexington, NationalResearch Institute of Fisheries Engineeri.Condition-dependent acoustic signals andtheir importance for resolving aggressiveconflicts in the skunk loach (Botia morleti):integrating sensory and behavioral ap-proaches.

In the skunk loach, Botia morleti (Pisces,Cobitidae) sounds are produced during ag-gressive contests over access to hidingplaces. These contests are costly for bothcontestants and signals that act honesty (re-liably) to indicate fighting ability could func-tion to minimize these costs. We examinedwhether sounds produced during contestsact as honest signals in B. morleti. To test thishypothesis we first quantified the relation-ship between sound characteristics and en-ergetic state (condition index) and docu-mented a positive correlation between con-dition index and peak-to-peak sound pres-sure level (loudness). Thus acoustic signalscould be used to avoid costly escalationswith fish in better condition, i.e., superiorcompetitors. We then manipulated the hear-ing ability of individual contestants to deter-mine whether signal misperception alteredcontest dynamics in a manner that was con-sistent with honest signaling, i.e., are esca-lations with superior competitors more com-mon when signals are misper-ceived? Wewill present the results of this experiment.

P3.100 SPEES, J.L.*, CHANG, S. A.,SNYDER, M.J., CHANG, E.S., University ofCalifornia, Davis. Interactive effects of os-motic and thermal stress on stress-respon-sive gene expression in the american lob-ster, Homarus americanus.

Organisms in nature experience multipleenvironmental stressors simultaneously. Formarine animals such as the American lob-ster, Homarus americanus, osmotic and ther-mal stress often occur concurrently or inclose temporal proximity. Presently however,few studies have examined the molecularbasis for responding to multiple stressors or

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whether such events can interactively alterthe expression of stress-responsive genesin vivo. To this end, we first characterizedthe effects of hypo- and hyper-osmotic stresson the lobster for 0.5, 1, and 2 h. We quan-tified the expression of the molecular chap-erone HSP90 (an indicator of reversible pro-tein damage) and polyubiquitin (an indica-tor of irreversible protein damage) as mea-sures of cellular perturbation in abdominalmuscle and hepatopancreas (a digestive tis-sue). We then exposed lobsters to either a 2h hypo- or hyper-osmotic stress followedimmediately by a 2 h thermal stress and abrief recovery (3 h). Balanced design two-way ANOVA was used to detect interactionsbetween salinity exposure and treatmenttime in the first experiment and to detect in-teractions between osmotic and thermalstress in the second experiment. Significantinteractions were found between salinityexposure and treatment time for both HSP90mRNA levels as well as polyubiquitin mRNAlevels for hepatopancreas; such interactionswere not observed for abdominal muscle.However, osmotic and thermal stress didinteract significantly to alter the expressionof both HSP90 and polyubiquitin in abdomi-nal muscle, as well as HSP90 expression inhepatopancreas. Polyubiquitin mRNA lev-els in hepatopancreas, although significantlyhigher than control levels, did not display asignificant interaction between osmotic andthermal stress.

S4.2 SPICER, J.I., University of Plymouth,UK. Development of cardiac function in crus-taceans: patterns, processes and implica-tions.

While our knowledge of cardiovascularfunction in adult crustaceans is reasonable,our understanding of how that functioncomes into being during ontogeny is still,quite literally, embryonic. In this presenta-tion I will briefly outline the different patternsof the onset and development of cardiacfunction in different crustacean groups.Thereafter our current understanding of themechanisms underpinning the developmentof cardiac regulation will be presented to-gether with an assessment of future researchpriorities. Finally the wider importance of

studying the development of cardiac func-tion will be explored. This includes using thecrustacean heart as a model for studyingthe ontogeny of physiological regulation andlinking life history characteristics to heart ratevariability during early development.

P3.75SPRAFKA, J.B., CHANG, E.S.,SNYDER, M.J.*, University of California,Davis. Insulin-like growth factor I (IGF-I) treat-ment results in time- and dose-dependentincreases in tissue glucose levels in thepenaeid shrimp Sicyonia ingentis.

Insulin-like growth factors (IGF) are im-portant regulators of vertebrate growth anddevelopment. We have previously reportedon the identity of IGF-like mRNA in decapodcrustacean muscles. The role(s) of IGFs, suchas IGF-I, in invertebrate systems remains un-clear. In this study, we examined the in vivoeffects of IGF-I treatment on glucose levelsin Sicyonia ingentis. We show that IGF-I in-jections promote both dose- and time- de-pendent increases in abdominal muscle andhepatopancreas glucose levels. Hepato-pancreas samples collected 15 min post-IGF-I injection (0.2 MUg/g wet wt.) had meanglucose levels approximately 30% higherthan both non-injected and control-injected(0.2 MUg /g wet wt.) shrimp. Glucose levelswere still 22% higher 30 min post-injection.Mean glucose levels in abdominal musclesamples 15 min after treatment were un-changed from controls, but at 30 min levelswere elevated to 23.2% above controls. Ourwork demonstrates that IGF-I elicits a dis-tinct metabolic response n this species. Therapid physiological effects suggest that anIGF-like peptide may regulate key metabolicprocesses in this decapod crustacean.(Funded by NOAA California Sea Grant R/A-108)

S12.5SPRING, J.H.*, HAZEL-TON, S.R.,University of Louisiana, Lafayette. Excretionin the house cricket, Acheta domesticus: ef-fects of cAMP on membrane dynamics, cellultrastructure and secretion.

In Acheta domesticus, the Malpighiantubules (Mt) are composed of three regions,each consisting of a single cell type. The cellsof the mid-tubule display the classic archi-

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tecture of transport epithelia, possessing ex-tensive basolateral infoldings and a densebrush border. The mid-tubule is secretory infunction and responds to endocrine stimu-lation. Our research centers on correlatingthe physiological response of the mid-tubulewith the structural changes within the cellsfollowing the addition of various secreta-gogues. One of the most striking ultrastruc-tural changes occurs when the Mt are stimu-lated with the second messenger analogue,dibutyryl cAMP. The increase in secretion rate(approximately doubling) is accompanied bynotable changes in ultrastructure, the mostprominent being membrane re-organizationto increase the surface area of thebasolateral infolds and vesiculation. Theextensive pattern of endomembrane distri-bution noted in unstimulated tissue disap-pears following stimulation and the concre-tions (spherites) begin to dissolve. The areaof the cell given over to vesicles/vacuolesmore than doubles over 420 s post-stimula-tion. We followed the membrane dynamicsof the mid-tubule using TEM, SEM coupledwith freeze-cleaving followed by extractionof the cytosol, and various fluorescent trac-ers. Using this SEM technique (developedin our laboratory) we were able to observethe increase in basolateral infoldings alongwith the presence of dilated areas of mem-brane suggestive of the vesiculation patternof stimulated tissue previously observed withTEM. Our findings suggest that there is anintricate endomembrane network that ve-siculates in response to rapid fluid transportpossibly to compartmentalize fluid to pre-vent dilution of the cytoplasm. Supported byNSF grant IBN-9807948 to JHS.

24.5 SRYGLEY, R.B., University of Oxford,Oxford. Locomotor mimicry among passion-vine butterflies Heliconius.

With regard to prey motion, the evolutionof mimicry has been investigated in threeareas: 1) locomotor mimicry, 2) anti-apostaticselection, and 3) escape mimicry. Locomo-tor mimicry is the similarity in motion of twodistantly-related prey species. Because ofevolutionary convergence in key morpho-logical features that are relevant to flight, con-vergence in the flight behavior of distasteful,

mimetic passion-vine butterflies in the ge-nus Heliconius was predicted. Applying amethodology developed in C.P. Ellingtoníslaboratory, I present evidence that mimeticHeliconius are more similar in wingbeat fre-quency and the degree of asymmetry in thewing motion than they are to their sister spe-cies. Anti-apostatic selection, or selectionagainst odd individuals, may be the selec-tive force for behavioral similarity amongM¸llerian mimics. Prey motion increases se-lection against odd individuals when preyare at high densities, and perhaps when theprey are M¸llerian mimics. Ultimately, the be-haviors of the different mimetic morphsshould converge on that behavior whichminimizes the energetic cost of flight. Apply-ing Ellingtonís aerodynamic models, I esti-mated the energetic cost of each mimeticmorphís flight behavior in order to qualita-tively predict the difference in height of eachfitness peak and the direction of convergentselection. Following adjustments for bodymass, mimetic H. melpomene and H. eratorequired more aerodynamic power than H.cydno and H. sapho. This difference was at-tributed to the slower flight speeds andhigher wingbeat frequencies of H.melpomene and H. erato. From morphology,locomotor mimicry with important limitationsis also predicted to occur in palatable spe-cies that appear like distasteful models (Ba-tesian mimics), and among palatable spe-cies that are color mimetic due to unprofit-able prey (or escape) mimicry.

5.4 STACH, T.*, TURBEVILLE, J. M., Uni-versity of Arkansas. Reconstruction of tuni-cate phylogeny using molecular and mor-phological data.

The phylogeny of the Tunicata and as-cidian families within the Tunicata was re-constructed using molecular and morpho-logical evidence. Mitochondrial cytochromeoxidase I (COI) and 18S rDNA sequencesof 15 tunicate species were obtained andaligned with gene sequences ofcephalochordates and craniates. Morpho-logical characters of larval and adult stageswere compiled from the literature and ana-lyzed cladistically. Implications of separateand simultaneous analyses of molecular

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and morphological data were examined.Aplousobranch ascidians were included ina molecular phylogenetic analysis for thefirst time. COI data and the combined analy-sis of COI data and morphological charac-ters do not support monophyly of theAplousobranchiata, whereas morphologicalcharacters suggest monophyly. When asingle aplousobranch species is included,Appendicularia (= Larvacea) nest within theAscidiacea in the analysis of the preliminary18S rDNA data and the combined molecu-lar (18S rDNA) and morphological analysis.In the morphological analysis Agnesiidaeand Octacnemidae (= Hypobythiidae) nestwithin the Phlebobranchiata (Entero-gona).Morphological evidence suggests that theSorberacea (= Aspiraculata), traditionallythought to represent a separate tunicateclass, are aberrant pleurogonid deep-seaascidians, constituting the sister group of theMolgulidae. No molecular data exist forAgnesiidae, Octacnemidae, andSorberacea. Morphological character evo-lution and implications for the reconstruc-tion of the chordate groundplan will be dis-cussed. The preliminary results show thatmore molecular and morphological data areneeded to reliably resolve tunicate and as-cidian phylogeny and acquisition of thesedata is currently underway.

P2.79STAKEBAKE, E.F., MEYERS, R.A.*,Weber State University, Ogden, UT. The al-batross shoulder lock: a biomechanical andimmunohistochemical study.

As a postural behavior, gliding and soar-ing flight in birds requires less energy thanflapping flight. Slow tonic and slow twitchmuscle fibers are specialized for sustainedcontraction with high fatigue resistance andare typically found in muscles associatedwith posture. Albatrosses are the elite ofavian gliders; as such we wanted to learnhow their musculoskeletal system enablesthem to maintain spread-wing posture forprolonged gliding bouts. We used dissec-tion and immunohistochemistry to evaluatemuscle function for gliding flight in Laysanand Black-footed Albatrosses. Albatrossespossess a locking mechanism at the shoul-der; internal and external tendinous sheets

extend from origin to insertion throughoutthe length of the deep layer of the pectoralismuscle. This fascial “strut” passively main-tains horizontal wing orientation during glid-ing and soaring flight. A number of muscles,which likely facilitate gliding posture, werefound to be comprised exclusively of slowfibers. These include Mm. coracobrachialiscranialis, extensor metacarpi radialis dor-salis and deep pectoralis. In addition, a num-ber of other muscles, including tricepsscapularis, supracoracoideus, and extensormetacarpi radialis ventralis, were found tohave populations of slow fibers. We believethat this suite of uniformly slow muscles isassociated with sustained gliding and isunique to birds that perform such behaviors.These findings demonstrate that albatrossesutilize a combination of slow muscle fibersand a rigid limiting tendon for maintainingprolonged, gliding posture.

43.5 STARCK, J.M., University of Jena. Mor-phological flexibility of the intestine of snakes.

The small intestine of snakes respondsto feeding by rapid upregulation of organsize. After absorption of nutrients the smallintestine size is down regulated to fastingsize. The mechanisms of the morphologicalflexibility of the small intestine are comparedin Burmese pythons (Python molurusbivittatus) which are infrequent feeding ‘sitand wait’ foraging snakes, and red sidedgarter snakes (Thamnophis sirtalisparietalis) which are actively hunting and fre-quently feeding snakes. Ultrasonography,light microscopy, transmission electron mi-croscopy, and flow cytometry were used tostudy the mechanisms of small intestine sizeresponse to feeding. Independent of the feed-ing strategies, both species showed thesame responsiveness of the small intestineto feeding and the small intestine had thesame histological architecture. The mucosalepithelium a was a transitional (pseudo-stratified) epithelium that allowed for sizechanges without production of new tissue.Driving force of the size increase were a fluidpressure pump (lymph and blood pressure)and incorporation of lipid droplets into theenterocytes. No cell proliferation was asso-ciated with upregulation of organ size. In-stead, cell proliferation, i.e., production of

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new tissue was observed during down regu-lation of organ size. A possible explanationis that cells that deteriorated during absorp-tion of nutrients were replaced when diges-tion and absorption ended. Based on pre-liminary comparative evidence it is sug-gested that the described histological prop-erties of the small intestine are an ancestralfeature of snakes, and, possibly, of other non-avian sauropsids (supported by German Re-search Council STA 345/5-1).

P2.11STARCK, M.J.*, HELM, B., SALZER,U., University Jena, Max-Planck Institute ofOrnithology, Andechs, University Jena. De-velopmental asymmetry in growingjapanese quail (Coturnix japonica).

Measures of fluctuating asymmetry (FA)may by used as a gauge of developmentalstability of various traits in growing animals;i.e., a high level of FA indicates labile devel-opment while low levels of FA stand for sta-bile development. In this study, we asked (1)whether levels of FA change during devel-opment, and (2) whether interactions be-tween environment and organism affect FA.In detail, we asked whether coefficients ofvariation (CV) of morphometric measure-ments as well as their FAs change duringontogeny. Further, we addressed the ques-tion whether interactions between the envi-ronment and the growing organism affectedFAs and patterns of morphological develop-ment. We studied developing tarsometatar-sus of Japanese quail (Coturnix japonica)from its first occurrence on embryonic day 5to adulthood. Coefficients of variation of tar-sal length were high during early and midembryogenesis. Coefficients of Variation andlevel of FA began to decline briefly beforehatching. A sudden and distinct drop of mea-sured FA occurred immediately after hatch-ing. During posthatching development, mea-sures of FA continued to decline to low adultvalues. If signed asymmetry was recordedfor each day post-hatching, we observed aclear pattern of alternating asymmetry. Con-clusions from our study are that (1) degreeof developmental stabilization (canalization)increases during ontogeny. (2) The steepdecline of FA immediately after hatching sug-gests that organism environment interactionsare an important contribution to shaping the

phenotype, i.e., reduce asymmetry, and (3)time series of alternating asymmetry sug-gest compensatory growth and left-right sig-naling during growth of tarsus.

S9.1 STEFANO, G.B., State University NewYork, Old Westbury. The beginnings of thestress response: opioid modulation in inver-tebrates.

It is evident that chemical signal mol-ecules mediate intercellular communication.During evolution, organisms using this formof communication have increased theirchances of survival, passing this trait on totheir descendents. Chemical communica-tion exhibits a greater level of sophistica-tion, i.e., synaptic, hormonal. The end resultof such chemical-communication mecha-nisms would be a higher degree of sophisti-cation and detailed information transfer,which allows for a greater number of behav-ioral characteristics (including afferent hor-monal influences), enhancing an organism’schance for survival in a changing environ-ment. Periodically, environmental changesmay represent an immediate adverse event,regardless of where an organism is on theevolutionary tree. In this regard, concerningany organism, a correct response to ensuresurvival is required: thus, the presence ofmorphine and proenkephalin, prodynorphinand proopiomelanocortin, and their derivedpeptides. In simple animals, the presenceof such derived peptides is not surprisingsince they must respond to similar chal-lenges from the environment, i.e., bacterial.Given the success of these signal moleculesin modulating the internal stress responsein invertebrates, they must have been con-served during evolution, presumably be-cause the signaling process was so difficultto achieve in the first place. Recent findingsnot only document the invertebrate presenceof signal molecules, exhibiting high se-quence identity associated with the "mam-malian" hypothalamic-pituitary -adrenal axisbut, their receptors as well. All in all, it ap-pears that the mammalian "stress-associ-ated" processes first existed in invertebrates,if not earlier. In this regard, evolution simplyplaced cognition on this basic foundation inman.

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P1.95STEGALL, V.S.*, KINSEY, S.A.,MCLELLAN, W.A., DILLAMAN, R.M., PABST,D.A., University of North Carolina,Wilmington. Biochemical changes in loco-motor muscle of harbor porpoise, Phocoenaphocoena, during starvation.

A primary locomotor muscle (M. longissi-mus) of stranded, emaciated porpoises wascompared to that of robust porpoises killedin fishing operations. We previously demon-strated that emaciated porpoises displayeddecreases in body mass, axial locomotormuscle mass, M. longissimus muscle fiberdiameters and fast twitch fiber-type areasequivalent to, or greater than, that seen inlaboratory animals undergoing starvation.This study investigates changes in musclebiochemical profiles of starved (n=5) and ro-bust (n=4) porpoises. A suite of enzymeswere assayed representing glycolysis, lipidoxidation, citric acid cycle, and amino acidoxidation. We report here the activities(MUmoles/min.*g wet wt.) for citrate synthase(CS), lactate dehydrogenase (LDH) and hex-okinase (HK). CS was chosen as a repre-sentative enzyme for the citric acid cycle; wehypothesized its relative activity would in-crease during starvation because of the in-creased need for lipid oxidation. LDH waschosen to monitor the muscle’s anaerobicmetabolism; we hypothesized its relativeactivity would decrease because of the in-creased atrophy of fast twitch fibers. HK waschosen as a representative enzyme for gly-colysis; we hypothesized its relative activitywould decrease because of the loss of gly-cogen during starvation. Our results showedthat CS increased by 49%, LDH decreasedby 40%, HK decreased by 35% and the ra-tio CS/LDH increased by 37% in starvedanimals. These results support the his-tochemical study and suggest a transition tothe use of oxidative slow twitch fibers as thereliance of metabolic fuel changes from glu-cose to lipid during starvation. Research sup-ported by Marine Mammal Health andStranding Response Program, NMFS, ONR,UNCW-CMS, and Sigma-Xi GIAR.

52.6 STEIN, R.W.*, WILLIAMS, T.D.,PLACE, A.R., DEL RIO, C.M., Simon FraserUniversity, Simon Fraser University, Univer-sity of Wyoming, University of Maryland. Age-

related differences in digestive function dur-ing migration in the Western sandpiper(Calidris mauri).

It is common practice to use species’mean values of standardized measures,such as BMR, to evaluate changes in en-ergy demands. However, relying upon spe-cies’ mean values becomes problematicwhen age-related differences are large andare not accounted for. The problem becomespronounced when conservation decisionsare being made, i.e. preservation of particu-lar migratory stop-over sites, on the basis ofthese measures. I use the digestive tract asa model system to evaluate individual per-formance in relation to meeting the ener-getic demands of migration. I evaluated func-tional aspects of the digestive tract at threelevels: a) uptake rates across epithelium us-ing the everted sleeve, b) morphology (his-tological analysis) and c) activities of twodigestive enzymes (pancreatic lipase andaminopeptidase-N) in three age-classes ofthe Western Sandpiper (Calidris mauri) dur-ing migration. I present these data in thecontext of whole organism performance anddifferences in energy demands for the dif-ferent age-classes. In particular I will showthat there appear to be problems associatedwith the use of the everted sleeve method(extensive tissue damage during eversion)in free-living birds (cf. captive birds that havebeen used in many previous studies). Thismay relate to changes in gut structure asso-ciated with captivity per se.

68.3 STEVENSON, R.D., University of Mas-sachusetts Boston. Building conceptualframeworks for teaching biology and physi-ology: theory, examples and a new role forSICB?

A recent publication from the NationalAcademy Press titled “How People Learn:Bridging Research and Practice” byDonovan et al. (http://books.nap.edu/html/howpeople2/ch1.html) highlights severalways to improve teaching and learning. Thereport states that deep factual knowledge, aconceptual framework and an organizationalknowledge are necessary to master a disci-pline. Biology as a discipline overwhelmsstudents with facts and is not as strong as it

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could be in providing conceptual frame-works. Furthermore the linkages betweenconceptual framework and factual knowl-edge are often not as explicit as they couldbe. I reviewed college biology and physiol-ogy textbooks to see what conceptual frame-works are offered. Biology texts discuss theprocess of science, levels of biological or-ganization, evolution, phylogeny, commonfeatures of life, while physiology texts usu-ally discuss levels of biological organiza-tion, structure-function relationships, regu-lation especially feedback and homeosta-sis and physical and chemical constraintson biological function. Older texts providefewer frameworks suggesting that teachingstrategies are changing. Comparative or en-vironmental physiology texts provided moreframeworks than did human anatomy andphysiology texts. SICB’s predecessor, ASZ,sponsored John Moore’s Science As A WayOf Knowing symposia that developed con-ceptual frameworks for Biology and resultedin a series of ASZ publications. Using theInternet, it is now possible to develop dy-namics conceptual frameworks based on theexpertise of the community of SICB mem-bers that could be an online resource. I ex-plore the possibility that such a web sitemight replace textbooks and generate rev-enue for the society.

P2.60STEWART, H.L, University of Califor-nia, Berkeley. Morphological heterogeneityamong zooids of encrusting colonies ofMembranipora membranacea induces pas-sive flow through the colony.

Encrusting bryozoans live in a velocitygradient at the base of momentum bound-ary layers in the fluid environment in whichthey live. As suspension feeders, their inter-action with the surrounding fluid is impor-tant in filter-feeding success, which is pro-portional to competitive ability and fitness ofthe colony. Active ciliary pumping by indi-vidual zooids of Membranipora mem-branacea creates incurrent flow that passesover tentacled-lophophores and is expelledin ‘chimneys’; regions of non-feeding zooidssurrounded by feeding zooids that have lo-phophores that are ~2x taller than the lo-phophores of non-chimney feeding zooids.This study was conducted to investigate the

possible induction of passive flow inducedthrough the colony by the interaction of am-bient flow and this morphological heteroge-neity among zooids. Particle imagevelocimetry (PIV) was used to quantify aver-age velocity of the excurrent flow from a chim-ney as a function of ambient flow speed.There was a significant correlation betweenthe velocity in the vertical direction throughthe chimney and ambient horizontal veloc-ity in the horizontal direction. This suggeststhat there may be induced flow through colo-nies with chimneys, even at the low Reynoldsnumber that characterizes the fluid environ-ment in which they live.

45.4 STEWART, J.R.*, HEULIN, B., EastTennessee State University, Johnson City,Station Biologique de Paimpont, France.Ontogeny of the extraembryonic membranesin oviparous viviparous lizards, Lacertavivipara.

Lacerta vivipara is a reproductively bi-modal species with allopatrically distributedviviparous and oviparous populations. Mor-phological, ecological and genetical simi-larities among populations indicate thatoviparous and viviparous populations areclosely related and diverged recently. Thisspecies provides a rare opportunity amongsquamate reptiles to compare the influenceof reproductive mode on intraspecific varia-tion in development of the extraembryonicmembranes. We studied ontogeny of theextraembryonic membranes of an oviparouspopulation for comparison with classical andrecent studies of viviparous populations.Morphogenesis of the yolk cleft and isolatedyolk mass is typical for Squamata. The yolkcleft extends across the abembryonic sur-face of the yolk vesicle shortly after oviposi-tion. The allantoic vesicle fills the embryonichemisphere of recently oviposited eggs anda vascularized chorioallantoic membranecontacts the eggshell over the surface of thishemisphere. The isolated yolk mass hasregressed and the chorioallantoic mem-brane completely encircles the egg in near-term embryos; both of these events are char-acteristic of other oviparous lizards. How-ever, one component of the ontogeny of theyolk sac has not been reported in other spe-cies. The novel feature is a secondary yolk

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cleft that develops as a sheet of intravitellinecells penetrates the yolk mass internal, andparallel, to the primary yolk cleft. The allan-toic vesicle grows into the secondary yolkcleft as it expands around the perimeter ofthe egg. Although the topology of the ex-traembryonic membranes in near-term em-bryos is similar to other oviparous species,the developmental sequence producing thattopology differs.

P1.99STEYERMARK, A.C.*, LAM, M., DIA-MOND, J., University of California, Los An-geles. Functional design of the gut.

Did animals’ bodies evolve such that ca-pacities of body components are matchedefficiently to maximum natural loads, war-ranting the motto “enough but not too much”?Series pathways raise a further question indesign optimality: do all steps have similarcapacities, or is there a single rate-limitingstep? Nutrient processing involves energeti-cally expensive organs arranged in series:absorption in the intestine, metabolism inthe liver, circulation by the heart, oxidationby lung gases, and waste excretion by thekidney. Thus, we tested concepts of designeconomy for the gut vis-a-vis other organsthat process nutrients. A practical problemin exploring organ matches of nutrient pro-cessing capacities is that nutrients normallyreach other organs from the intestine, so thatthe nutrient loads on those other organs can-not be separately manipulated. We circum-vented this problem by nourishing labora-tory rats with total parenteral nutrition (TPN)-a clinical procedure for delivering nutrientsdirectly into the circulation of human patients.TPN permits us to administer an identicalliquid nutrient mix to rats either as TPN ororal feeding. Thus, under circumstances ofnourishing a rat with TPN, with any potentialintestinal bottleneck eliminated, can the ratprocess far more nutrients than its intestinecan absorb? Or are processing rates of othergut organs matched to intestinal absorptionrates? Or can the intestine absorb nutrientsfaster than other organs can process them?Which, if any, nutrient-processing organ israte-limiting?

P1.22STODDARD, S.T., JIN, Y., CHENG,C.H.*, DEVRIES, A.L., University of Illinois

at Urbana-Champaign. Antifreeze potenti-ating protein in Antarctic notothenioid fishes.

The ability of Antarctic notothenioid fishesto survive in ice-laden waters at -1.9o C hasbeen attributed to a group of antifreeze gly-coproteins (AFGPs). In the absence ofAFGPs, the freezing point of body fluids inthe fish would be approximately -1o C due tocolligative properties. By binding to ice crys-tals and inhibiting their growth, AFGPs sup-press the freezing point another 1.2o C. To-gether, this gives an organismal freezingpoint of about -2.2o C, sufficient for the fish toavoid freezing. However, it has also beenobserved that the freezing point of nativenotothenioid fish serum can reach as low as-2.7o C, suggesting that another factor is ac-tive in preventing ice growth. We have nowdiscovered a second ice-active serum pro-tein. Alone, this protein displays weak anti-freeze activity and does not contribute theremainder of the observed activity in nativeserum. However, when mixed with AFGPs1-5, it was found to potentiate antifreeze ac-tivity up to 5 or 6 fold, thus accounting for thefull freezing point depression observed innative serum. This protein, called antifreezepotentiating protein (AFPP), has a molecu-lar weight of 15,489 kD. It is present at vari-able concentrations (1 - 4 mg/ml) in the bloodof notothenioids; the highest value found inspecies associated with the iciest habitats.Proteolytic digestion and protein sequenceanalysis has yielded partial sequences thatappear to contain a repeated Ser-Ala-Glymotif. Current work is focusing on the use ofprimers derived from the protein sequenceto generate full length AFPP cDNA by RT-PCR. There are no current sequences in thedata similar to the AFPP partial sequence.Therefore AFPP is a novel ice-binding pro-tein that together with AFGPs forms the firstexample of a two-protein antifreeze systemin fish.

S13.3STOLLNITZ, F. *, WOODIN, T. S., Na-tional Science Foundation, National ScienceFoundation. NSF funding opportunities re-lated to education.

Funding opportunities currently availablefor educational activities both in the educa-tion and the research divisions will be pre-sented. We will also review key information

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often omitted by proposers. As a means ofhighlighting important components of a sub-mission to NSF programs, participants willhave an opportunity to review and commentupon a proposal. Details of the programsare available on the NSF Web site(www.nsf.gov) under “Biology,” “Education,”and “Crosscutting.”

P3.32STRANGE, R.M., Southeast MissouriState University. Evolution of sexual dimor-phisms in spottail darters (Teleostei:percidae): fitness sets, phylogenetics, and atest of the egg-mimic hypothesis.

I investigated the dynamics between re-productive ecology and morphological phe-notypes among spottail darters by develop-ing a fitness set model. Spottail darters ex-hibit two types of sexual dimorphism, andboth presumably related to male resource-defense polygyny. My model considers malephenotypes as conflicting signals in matechoice behavior. Large male size is an hon-est signal in my model, by which large malesobtain and defend better nests. Femalechoice for large males increases female fit-ness. Males of some species develop largeknobs supported by rays of the second dor-sal fin. Fin knobs are hypothesized to act asegg-mimics used to attract receptive females,if females selectively deposit their eggs innests that already contain eggs despite thesize of the male guarding that nest. Egg-mimicry is a false signal in my model. Fe-male choice for males exhibiting egg-mim-ics may decrease female fitness when nestsites are limiting. Medium size males withsmall knobs are at a disadvantage in mymodel, as they lack the large size requiredto acquire nest sites and effective egg-mim-ics. Phylogenetic relationship among spottaildarters is consistent with the model: Largeegg-mimics evolve twice, and are alwaysassociated with a reduction in male size.Species in which egg-mimicry is maintainedoccur in habitats in which nest sites are notlimiting. Further, large male size has re-evolved in one species restricted to nest-poor habitats with a simultaneous reductionin egg- mimics.

S8.3 SUMIDA, S.S., California State Uni-versity San Bernardino. Biological principals

that drive digital effects and strategies of ani-mation: trading lessons between vertebratemechanics and commercial entertainment.

Comparative morphological studies andresponsible strategies of animation (both tra-ditionally hand-drawn and computer gener-ated) both require an understanding of struc-ture, function, ontogenetic variation, andsexual dimorphism. Within animation, differ-ent techniques utilize slightly differing em-phases. Traditional hand-drawn animationis focuses on superficial musculoskeletalanatomy. Dietary strategy (carnivory, her-bivory, or others) informs the type the basicmusculoskeletal patterns and locomotor be-havior employed. Digitally created animalcharacters demand intimate knowledge ofthe skeleton as a first principal, as it is a skel-etal wireframe that drives the movement ofthe character. Current standards require thatthe underlying skeleton (usually simplified)drive the movement of modeled soft tissue. Itmay be argued that restricting study or analy-sis to external structures, or having bonesmove muscles (as opposed to the converse)represent inappropriate approaches to studyand representation of movement. This per-spective is shortsighted. Rather, these nec-essary approaches present "exercises" or"problems" that may be solved with a thor-ough knowledge of how integrated biome-chanical systems operate. More extreme "ex-ercises" are presented by the needs of com-mercially driven storylines. Dinosaurs andmammals don't speak. Puppies aren't nor-mally found in litters of over 100, or even101, individuals. Graviportal elephants areincapable of galloping and an extendedphase floating. Hybrid organisms composedof taxa that crisscross the range of vertebrateclasses do not exist in the real world. How-ever, if they did, how would you solve theproblems? The answers lie in understand-ing comparative vertebrate anatomy andfunction.

P3.17SUMIDA, S.S.*, DEVLIN, K.R., Cali-fornia State University San Bernardino. Fea-tures of transitions between vertebrate ma-jor groups of terrestrial vertebrates.

The advent of cladistic analysis has pro-vided more rigorous means of defining lin-eages. Interpretations of the stratigraphic

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range or nature of the transition depend onthe use of crown-clade or node-based ap-proaches. In seeking common patterns, werestrict ourselves to transitions that: (1)characterise what have traditionally beenreferred to as “classes” of vertebrates; and(2) reflect, as least in part, significant envi-ronmental changes. The beginning and endof the water to land transition (origin of tetra-pods and origin of amniotes), and the dino-saur to bird transition may each becharacterised by the exploitation of a newniche (or niches), be they physiographic,physiological or both. Most transitions pro-vided profound new opportunities for habi-tat use, food acquisition, and predator avoid-ance. Features of transitions between majorgroups may be obvious from fossils, onlyindirectly evident, or not at all discernible.Respective examples include: the develop-ment of weight-bearing limbs in basal tetra-pods (obvious), addition of a slow-openingphase to prey capture in basal amniotes (in-direct evidence from morphology), and po-tential refinement of endothermy related topre-existing insulating structures (primitivefeathers inherited from mani-raptorantheropod dinosaurs) in basal birds. This lasttransition is a matter of some recent mediaattention, but no controversy about bird ori-gins actually exists, as all phylogenetic analy-ses exclude Longisquama from close rela-tionship with birds, its possession of “feath-ers” remains contentious, and many the ar-guments to support its supposed relation-ships to birds are those previously used toreject a theropod relatiionship with birds.Supported by the CSU Tyrannosaurusproject.

P2.6A SUMMERS, A.P., ROWE, T.,KETCHAM, R.A., University of California,Berkeley, University of Texas, Austin, Uni-versity of Texas, Austin. Ontogeny of thehornshark chondrocranium and the evolu-tion of trabecular cartilage.

The skeleton of the sharks, rays, andchimaeroids is composed of cartilage, someof which is calcified. The vertebrae are com-pletely calcified, while the remainder of theskeleton has one or more thin layers of cal-cified blocks (tesserae) covering a core ofuncalcified cartilage. In a clade of stingrays

containing hard prey specialists an internalnetwork of calcified struts augments the sur-face calcification. This strut-reinforced tissueis called trabecular cartilage. Some sharks,most notably the heterodontids, also eat hardprey. We examined a size series ofHeterodontus francisci with a high resolu-tion CT scanner for evidence of trabecularcartilage and to examine the morphology ofthe jaw joint. The CT scans and dissectionrevealed no trace of trabeculae. The jawmechanism is the mechanical antithesis ofthat of the hard prey crushing stingrays. Therays have a well-calcified symphysis but theupper and lower jaws meet at a joint thathas a large uncalcified region. In contrastheterodontids have an extremely loose,uncalcified, ligamentous symphysis and theupper and lower jaw joints form a well-calci-fied hinge joint. This raises the possibility thatthe left and right side of the shark’s jaws workas levers with the fulcrum at the joint. Dis-section of other shark taxa that are reportedto eat hard prey, Sphyrna tiburo andOrectolobus ornatus, did not reveal any tra-becular cartilage. Trabecular cartilage ap-pears to be an evolutionary innovation, con-fined to the myliobatid stingrays that allowsthem to eat harder prey than other cartilagi-nous fishes.

S9.15SUMMERS, C.H., Univ S Dakota. So-cial interaction over time, implications forstress responsiveness.

Behavioral interaction during social situa-tions is a continuum of action, response, andreaction. The temporal nature of social inter-action creates a series of stressful situations,such as aggression, displacement from re-sources, and the persistent psychologicalthreat accompanying social hierarchy. Theebb and flow of neurochemical and endo-crine secretions during social stress providea unique tool for understanding individual-ized responses to stress. Each social stationis an adaptive response to a stressful socialcondition, resulting in unique neuroendo-crine and behavioral responses. By exam-ining the temporal changes of limbicmonoamines and plasma glucocorticoids,aspects of mechanisms for adaptationemerge. The similarity of temporal patterns

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induced by social stress among fish, rep-tiles and primates are remarkable. Even dif-ferent specific coping mechanisms point outthe similarity of vertebrate stress responses.The lizard Anolis carolinensis exhibits aunique sign stimulus generated during so-cial stress by the sympathetic nervous sys-tem that serves as a temporal landmark todistinguish neuroendocrine patterns. Duringsocial interaction dominant males have ashorter latency to eyespot darkening thanopponents, inhibiting aggressive display.Eyespot coloration can be delayed using aserotonin reuptake inhibitor, causing domi-nant social status in many animals to be lost.Reversal of social status via serotonergicactivation appears to mimic chronic sero-tonergic activity. The pattern of eyespot dark-ening, faster in dominant males, is coinci-dent with that for serotonergic activity. Thefundamental temporal relationship betweendominant and subordinate limbic monoam-inergic activity over a continuous course ofsocial interaction appears to be a two-phaseresponse, temporally specific to brain re-gion, and always faster in dominant indi-viduals.

P3.31SWANSON, C.A., Florida State Uni-versity, Tallahassee. Positive effect of in-creasing egg mass size on juvenile successin the apple murex snail, Phyllonotuspomum.

Packaging and placement of offspring isan important aspect of life history because itcan directly affect fitness in terms of offspringsurvival. Previous studies addressing theeffect of egg mass structure on embryo suc-cess suggest that, due to a lower oxygendiffusion coefficient in aquatic environments,increasing egg mass size without compen-sation for spacing, size, or number of em-bryos decreases embryo survival. Femaleapple murex snails, Phyllonotus pomum, ex-hibit communal egg-laying in which numer-ous females simultaneously lay clutches ofegg capsules in a single mass. These massescan reach up to 2.3L. Because of the sheersize and 3-dimensional structure of thesecommunal masses, I would expect to find anegative affect on juvenile success as masssize increases. Contrary to predictions basedon empirical studies in other taxa, my data

on Phyllonotus pomum show a trend of in-creasing juvenile number at time of hatch-ing with increasing mass size. This suggeststhat larger mass sizes may actually provideprotection for developing embryos in cer-tain species.

S11.8SWARTZ, S.M.*, STOCKWELL, E.F.,Brown University, Providence, RI, BrownUniversity, Providence, RI and DalhousieUni. Wing architecture and maneuverabilityin bats: a 3-d kinematic approach.

Both the flight capabilities and the wingstructure of extant bats are diverse, and manystudies have sought the morphological ba-sis for bat flight performance, including ma-neuverability. Most analyses of the relation-ship between wing structure and flight ma-neuverability have selected descriptors ofwing morphology based on the aerodynam-ics of fixed-wing aircraft. In particular, singlevalues for wing area, wing loading, and as-pect ratio, defined at an estimated mid-downstroke posture, have been employedas descriptors. Here, we suggest that flap-ping flight, particularly the ability to performthree-dimensionally complex maneuvers,can be better related to wing design by mor-phological and kinematic descriptors thataccount for the intrinsically dynamic andthree-dimensional nature of flight. We em-ploy three-dimensional kinematics of wild-caught bats in wind-tunnel and obstacle ar-ray flights to demonstrate the considerablevariation in wing conformation that may beassociated with given values of static mid-downstroke wing area, loading, and aspectratio. We propose some descriptors of wingform based on three-dimensional kinemat-ics, and suggest directions for future work.

32.3 SWIDERSKI, D.L., University of Michi-gan. Diversity of patterns of variation in thelower jaw of tree squirrels.

Squirrels have a reputation for beingmorphologically conservative, and someinvestigators explicitly argue that most evo-lution of squirrel morphology can be de-scribed by an allometric trend. Most previ-ous morphometric studies of squirrels haveused sets of distance measurements. Suchstudies are predisposed to find evidence of

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allometric constraints because the measure-ments are all correlated with size and thusare correlated with each other. Geometricmorphometric methods are free of this biasbecause size and shape are evaluated in-dependently. In this study, I am using geo-metric methods to examine patterns of varia-tion in the lower jaw of the fox squirrel, Sciurusniger. Analyses of adult variation in two popu-lations indicate that shape features are nothighly correlated with each other, or with size,in either population. Comparisons betweenthe populations show that they differ in bothsize and shape of the jaw. However, thedifference in shape is not consistent with ex-trapolation of juvenile growth from thesmaller adult size to the larger adult size.These results indicate that evolution of jawshape in squirrels may not be as constrainedas previous studies suggested.

3.3 SYME, D.A.*, SHADWICK, R.E., Uni-versity of Calgary, AB, Scripps Inst. of Ocean-ography, University of California. Mechani-cal power production by internal red muscleat different longitudinal body positions in skip-jack tuna (Katsuwonus pelamis) in relationto swimming.

The work loop technique was used tostudy power output by internal red musclefrom skipjack tuna, to understandthe primaryfunction of this muscle in swimming, howdifferent strain amplitudes at different musclelocations affect performance, and how workand power output are affected by swimspeed. Red muscle was isolated from ante-rior (0.4L) and posterior (0.7L) positions(L=total body length) and subjected to sinu-soidal length changes and stimulus param-eters determined previously from swimmingfish or those producing maximal net work, at25oC. The optimum activation phase andduration decreased with increasing fre-quency, but were the same for anterior andposterior muscle. At test frequencies corre-sponding to tail beat frequencies used insteady swimming (3-5Hz) near maximalpositive work was produced when the strainand activation conditions measured in swim-ming fish were used. Net work per cyclepeaked at 2-3Hz and dropped to zero above15 Hz. Maximum power occurred at 5Hz, butpower production remained substantial be-

yond 10 Hz. Compared to anterior muscle,posterior fibers had higher power output(133 vs 79 W/kg), significantly shorter twitchrise times (60 vs 80 ms), but similar relax-ation times. The close agreement betweenstrain amplitude and activation parametersused in vivo and those producing maximumwork per cycle in vitro, and the match be-tween the frequency for peak power and tailbeat frequencies used for cruising suggestthat tunas use red muscle all along the bodyfor maximal power generation during steadyswimming. The maintained power produc-tion at higher frequencies suggests that redmuscle may also contribute power duringfast swimming.

S2.3 TABIN, T., Harvard Univ Med Sch.Genetic cassettes and the evolution of regu-latory networks patterning the embryo.

As genetic regulatory networks underly-ing development have been uncovered in avariety of organisms, a recurring theme isthat the same sets of genes often act in con-cert in different developmental pathways inthe ontogeny of one organism and in bothhomologous and non-homologous settingsin distantly related organisms. A challengeis to explain how such genetic “cassettes,”have been co-selected. An interesting caseis the cassette of Pax, eya, six, and dachs-hund genes, first described in the context ofDrosophila eye development. There is a syn-ergistic regulation of eye formation by eya,so(a six gene)and dac. These genes arelinked in their regulation so that each posi-tively affects the expression of the others.Moreover,all these genes participate in apositive feedback loop with the upstreamgene eya, a Pax6 homologue. We havefound that an analogous regulatory networkin vertebrate muscle development involvingeya2, six1, dac2, and Pax3. Moreover, othermembers of these families are co-expressedduring development of the vertebrate earand eye. Several evolutionary issues needto be explored. The co-selection of eya, sixand dac genes is likely driven by the factthat their gene products physically interactin a functional complex. Different family mem-bers may provide different specificities(andthe same genes may also function indepen-dently of each other in different settings),but

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it is easy to imagine that expression of onewould favor recruitment of a partner andsubsequent linking of their regulation. Harderto explain is the similar epistatic relationshipwith different Pax genes, since they do notinteract physically and the Pax genes inquestion are actually quite distantly relatedfrom one another. Finally not all the geneticinterrelationships between these genes inthe fly eye and vertebrate myogenic cellsare recapitulated in the vertebrate eye andear, which needs to be explained.

39.4 TAMMERO,L.F.*, DICKINSON, M.H.,University of California, Berkeley. The pat-tern of optic flow determines flight behaviorin freely flying Drosophila.

While flying through its environment insearch of food, a fruitfly (Drosophila) mustintegrate input from several sensory modali-ties. To study the behavioral patterns thatemerge from the interactions of these sen-sory systems, we reconstructed three-dimen-sional trajectories from images taken by ste-reo infrared video cameras during free flightwithin a controlled arena. Flies move throughtheir environment using a series of straightflight segments separated by rapid turnscalled saccades. Analysis of the trajectoriessuggests that saccades are fixed motor pat-terns that alter course by approximately 90degrees. For eachposition in the flight tra-jectory, we calculated the fly’s angular andtranslational velocities and reconstructed thevisual environment from the fly’s perspec-tive. From these reconstructions, we deter-mined the optic flow experienced by the flyduring the course of its flight. Analysis ofthese data suggests that optic flow does notalter course direction during the straight seg-ments and that the mechano-sensory hal-teres, which act as an inertial guidance sys-tem, dominate this portion of free flight be-havior. However, reverse correlations of thespatially integrated optic flow suggest thatimage expansion is the signal that triggerssaccades. In summary, our data suggest thatcomplex behavioral patterns seen duringfree flight emerge from interactions betweenthe flight control system and the visual envi-ronment.

39.3 TARSITANO, M.*, DICKIN-SON, M.,

University of California, Berkeley. Visual-ol-factory fusion in the flight behavior of Droso-phila.

Food is often associated with odor, soolfaction is an important sense which ani-mals use to guide them to food. Course con-trol in insects, however, is strongly influencedby visual cues. We are testing Drosophilato see how the visual algorithms they use tocontrol flight change to enable them tosearch for food in the presence of attractiveodors. We examined the 3-D flight paths offlies within a 100 x 60 cm chamber underthree conditions: with the wall of the cham-ber covered with a background of randomlydistributed white and black squares, with thewall covered with a background but also withan odor source embedded in its floor, andwith an odor but no visual background. Theflies tended towards the middle of the arenawhen tested with the random background(condition #1). In addition, flies flew at aheight between 200 and 300 mm. Whentested with a background and an odor (con-dition #2), flies flew around the location ofthe odor and at a height between 0 to 100mm. When flies were tested with an odor butno background (condition #3), they couldnot locate the odor in the horizontal plane.However, the flies flew at a height between0 - 100 mm, the same altitude as per condi-tion #2. Our tests suggest that optic flow isrequired for the localization of an odorsource. The process whereby one sensorymodality (olfaction) modulates another sen-sory mediated behavior (vision) is termed'sensory fusion'. It is not clear if the mecha-nism that enables a fly to localize the alti-tude of an odor source also requires visualinput. In the case of vertical localization, fliesmight use the top and bottom edges of thearena as visual cues.

P3.76 TASI, T., MAURES, T.*,FUNKENSTEIN, B., DUAN, C., Universityof Michigan, Ann Arbor, University of Michi-gan, Ann Arbor, Israel Ocean. & Limno.Res. Inst., University of Michigan, Ann Ar-bor. Molecular cloning and expression ofinsulin-like growth factor binding protein-2 in the gilthead seabream, Sparus aurata.

The insulin-like growth factors (IGFs) inextracellular fluids are bound to several high-

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affinity binding proteins (IGFBPs). The circu-lating IGF/IGFBP complexes prolong thehalf-lives of IGFs and buffer the acute hy-poglycemic effects of IGFs. Locally ex-pressed IGFBPs may also provide a meansof localizing IGFs in defined areas and mayalter IGF bioactivity by modulating the ligandreceptor interaction. In this paper, we reportthe cloning of an IGFBP cDNA from thegilthead seabream, Sparus aurata. ThecDNA encodes a protein of 285 amino ac-ids. The primary structure of this protein is43~49% identical to that of zebrafish,chicken, rat, mouse, and human. The se-quence identity of seabream IGFBP-2 withother human IGFBPs ranges from 28-34%.Northern blot analysis revealed that theseabream IGFBP-2 transcript is approxi-mately 1.8 kb and is highly expressed in theliver. Analysis of IGFBP-2 mRNA in variousadult tissues using RT-PCR revealed its ex-pression in all tissues studied, with the high-est levels in liver, skin, gonad and pyloriccaeca. The hepatic mRNA levels of IGFBP-2were greatly reduced in growth hormone-treated animals. This data is in agreementwith the role of IGFBP-2 function as a nega-tive growth regulator in the growth hormone-IGF-I axis. Transcripts for IGFBP2 were de-tected throughout early development in un-fertilized eggs, embryos and larvae, withhighest levels observed on days 3-6 afterhatching, suggesting that this mRNA is theproduct of both the maternal and embryonicgenomes. These data suggest that IGFBP-2 is expressed from the earliest stages ofdevelopment and may play an important rolein regulating growth and development in fish(Supported by BARD Grant IS-2769096Rand NSF Grant IBN-9728911).

P3.51TAYLOR, M.H.*, CALLA-WAY, S.B.,University of Delaware. Comparative analy-sis of ovarian contraction in some teleostfish.

Contraction of ovaries has been dem-onstrated in the mummichog, Fundulusheteroclitus and several other teleosts. Wehave expanded this information by record-ing spontaneous contractions and the re-sponse to acetylcholine in ovaries of thestriped killifish, Fundulus majalis, the Atlan-

tic silverside, Menidia menidia, and thepumpkinseed, Lepomis gibbosus sus-pended in a smooth muscle bath containinga modified Ringer’s solution. Ovaries of allthree species produced similar contractionsin response to 10 -5 M acetylcholine. Spon-taneous contractions in F. majalis, and M.menidia occurred in a series of single peakswith frequencies and amplitudes similar tothe pattern previously observed in F.heteroclitus. Those seen in L. gibbosus hada lower frequency and greater amplitude,with a series of superimposed higher fre-quency contractions. These results suggestthat ovarian contraction may be a commonphenomenon in the Antherinidae andFundulidae which share many reproductivecharacteristics including the occurrence ofsemilunar reproductive cycles. TheCentrarchidae are nest-building Percoidswhich are taxonomically distant from theother species analyzed.

52.3 TELANG, A.*, CHAPMAN, R.F.,WHEELER, D.E., University of Arizona.Sexual differences in protein and carbohy-drate utilization by larval tobacco budworm,Heliothis virescens (f.).

Female Lepidoptera are often heavierthan males, presumably due to greater foodconsumption. Our previous studies indicatedthat female Heliothis virescens caterpillarsuse both feeding and post-ingestive pro-cessing as mechanisms to meet nutrientneeds. Our present report focuses on thelatter mechanism. Post-ingestive responsesto four different diets containing protein andcarbohydrate at various concentrations wereanalyzed for fifth stadium Heliothis virescenscaterpillars of both sexes. Amounts eaten,excreted and used toward growth were mea-sured across the fifth stadium. Both femaleand male larvae differentially utilized in-gested protein and carbohydrate with fe-males achieving greater mean relativegrowth rate and protein-derived growth onall four diets. Results suggests that femalesare capable of more efficiently utilizing in-gested protein toward such growth. Chemi-cal analyses of frass nitrogen content sug-gest that ammonia excretion may be em-ployed by caterpillars under high protein,low carbohydrate diet conditions.

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P3.10TEMKIN, M. H.*, NELSON, M. L.,SNELL, A., ERICKSON, J. M., St. LawrenceUniversity, St. Lawrence University, CornellUniversity, St. Lawrence University. Geneticvariation in the freshwater mussel Elliptiocomplanata from Northern New York.

Freshwater mussels are an importantgroup of animals inhabiting the rivers andlakes of North America. Many native popu-lations of freshwater mussels in theAdirondack highlands and St. Lawrence low-lands have been lost or are endangeredbecause of the introduction of the exotic spe-cies Dreissena polymorpha (zebra mussels)and Dreissena bugensis (quagga mussels).The loss of populations within the range of aspecies may significantly effect the geneticdiversity contained within that species. Here,we examine the genetic variation at two mi-tochondrial loci of the freshwater musselElliptio complanata. Fifty E. complanata werecollected from fifteen sites in northern NewYork. After isolating DNA from individuals,nested PCR protocols were used to amplifya 400 bp segment of the cytochrome C oxi-dase subunit I (CO I) gene and a 362 bpsegment of the 16s rRNA gene. Variationamong PCR products for each gene werescreened using single stranded polymor-phism conformation analysis (SSCP). InitialSSCP analysis revealed six CO I alleles andfour 16s rRNA alleles. To identify how PCRproducts of each gene differed, we clonedand sequenced each PCR product. We usethe DNA sequences of the CO I and 16srRNA genes to assess genetic diversity andevaluate the roles of historical and contem-porary processes in determining the geneticvariation within E. complanata populationsin northern New York.

68.4 TEMPLE, J. G., Mary Washington Col-lege, Fredericksburg, VA. Animal magnetism:using magnetic stir bars to learn about di-gestive passage rate in snakes.

Snakes, as classic ectotherms, are inter-esting subjects for studying the relationshipbetween temperature and physiological pro-cesses. They are particularly well-suited forstudying digestive passage rate given thelinear anatomical arrangement of their di-gestive tracts. In this paper, a simple and in-

expensive laboratory exercise in which yourstudents can design and carry out an ex-periment to track the passage of an ingestedmeal through the digestive system of thegarter snake (Genus Thamnophis) is de-scribed. Teflon-coated micro stir bars areplaced in a meal and their location in thesnake is determined using a standard com-pass. Using the guided inquiry approach,the students are provided background infor-mation on the topic and the experimentaltechniques, and they are then allowed todevelop their own hypotheses and designtheir own experiments with guidance fromthe instructor. The digestive passage rate isdetermined over a range of temperatures,and the direct relationship between tem-perature and digestive passage rate can beeasily demonstrated using relatively smallsample sizes. This exercise is effective fordiscussions of comparative physiology andanatomy in vertebrates. The straightforwardtechnique can be easily modified to fit theneeds of courses with all levels of students.

S4.1 TERWILLIGER, N.B., RYAN, M., Uni-versity of Oregon, Charleston. Ontogeny ofcrustacean respiratory proteins.

The respiratory proteins hemocyanin(Hc) and hemoglobin (Hb) share the func-tion of oxygen transport, but the proteins,their active sites and the metal ions that bindthe oxygen are totally different. Either Hc orHb, but not both, is expressed in thehemolymph of many arthropod crustaceans.Hb is present in Branchiopoda, Ostracoda,Copepoda, rhizocephalan Cirripedia andone suborder of amphipodan Malacostracawhile Hc has been described inMalacostraca. Recent work by several labo-ratories have provided new information onthe gene structure, site of synthesis and ex-pression of branchiopod Hbs and suggeststhey are excellent model organisms for stud-ies of hypoxia sensors and oxygen responseelements during development and adultstages. Studies on Hc ontogeny have shownfunctional changes in Nephrops andHomarus Hcs. The focus in our laboratoryon the ontogeny of Hc in the Dungenesscrab has demonstrated that both structureand function of Hc change from megalopato adult crab. The Hc of an oceanic megalopa

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contains 4 subunits. A 5th subunit appearsabout the time of metamorphosis to 1st juve-nile instar, and expression of a 6th subunitbegins four or five molts later. The timing ofonset of adult Hc can be altered by food avail-ability and/or temperature. Experiments test-ing the potential role of magnesium concen-tration on regulation of Hc ontogeny point tonon-specific stress as an additional factor inthe timing of the development shift from ju-venile to adult Hc. We have identified a Hc-like protein in nauplii and juvenile Artemiausing mono- and polyclonal antibodies. Thismay indicate simultaneous expression ofboth Hb and Hc gene families in the sameorganism.

39.2 THEOBALD, J.C.*, O’CARROLL, D.,University of Washington, Seattle. Neuralstrategies that optimize motion detection inthe crepuscular hawkmoth Manduca sexta.

Perhaps the greatest demand on visualsystem design occurs with the transition fromday to night, since illuminance can differ bya factor of 108. For an animal to function indarker conditions, its visual system mustdeal with an inherently ënoisierí image. Thisis a special problem for hovering hawkmoths,as the detection of low image velocities re-quired for hovering is visually demanding.We tested the hypothesis that hawkmothsuse not just optical, but neural strategies toadapt their vision and motion detection tolow light levels. We compared the responsesof neurons in the lobula plate (a retinotopicneuropil rich in motion-sensitive cells) andphotoreceptors to a moving sinusoidal stimu-lus of varying stripe density (spatial fre-quency), rate (temporal frequency), and lightintensity. Our results support the hypothesisthat hawkmoths use temporal neural filter-ing at low light levels, but not spatial filtering.Because the velocity of an image is the quo-tient of its temporal and spatial frequencies,low velocity information is found in both lowtemporal and high spatial frequencies. Bysacrificing only high temporal frequency in-formation, hawkmoths improve the signal tonoise ratio of a dark image, but retain thehigh spatial frequency information requiredfor hovering in spatially complex habitats.

32.2 THEODOR, J. M.*, JANIS, C. M.,

BOISVERT, B., University of California, LosAngeles, Brown University, Providence RI,Brown University, Providence RI. Camelidfoot morphology and the evolution of thepacing gait.

Among wild mammals, camels are uniquein their use of a running pacing gait insteadof a trot. Extant camelids are characterizedby features unusual among artiodactyls: theirfeet are secondarily digitigrade, with a broad,flat pad in place of hooves; and the distalmetapodials are widely splayed. These fea-tures have been assumed to represent anadaptation for pacing, to increase lateral sta-bility in this rolling gait. Morphometric analy-sis of 16 measurements of the metapodialsand phalanges of extant camelids and ru-minants revealed distinct differences. Extantcamelids have relatively longer first phalan-ges with larger, flattened distal articulationsextending onto the volar surface, and thedistal phalanx is short and flat, while rumi-nants have longer second phalanges withan extension of the distal facet onto the volarsurface, indicating unguligrade foot posture.The sample included 18 genera of extinctcamelids from the Tertiary of North America,most of which showed some morphologicalfeatures typical of modern forms, and a num-ber clustered with the extant camelids. Ex-tinct members of the Camelinae andProtolabis show all of the morphological fea-tures of modern camelid foot posture, butthe current phylogeny indicates they evolvedthese features in parallel. Independent evi-dence from trackways associated withProtolabis shows that this taxon used a pac-ing gait, indicating that these foot morpholo-gies are correlated with pacing. Evolution-ary change towards a modern camelid-likecondition was also seen within the subfami-lies Stenomylinae and Miolabinae. Theseparallel changes in camelid locomotoranatomy occurred in the late Oligocene orearly Miocene, preceding the formation ofopen grassland habitats in the late Miocene.

25.1 THOMAS, F.I.M., BOLTON, T.F., Univer-sity of South Florida. Mechanical forces im-posed on echinoid eggs during spawning:mitigation of force by fibrous networks withinegg extracellular layers.

Eggs of echinoids are exposed to me-

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chanical forces during spawning. The mag-nitude of these forces depends on the prop-erties of the eggs and the relative dimen-sions of the egg and gonopores. Recentevidence suggests that mechanical forceshave the propensity to damage eggs,thereby reducing their fertilizability, or to de-stroy them. Jelly coats that surround echino-derm eggs have a composite structure ofirregularly arranged fiberous networks em-bedded in a matrix. These fibrous networkshave characteristics that are similar to engi-neered and biological materials that areknown to reduce the transmission of me-chanical forces to other structures. Experi-mental evidence shows that these coats pro-tect eggs from shear stresses and reducethe strain imposed on eggs under a com-pressive force. Given the similarity of the jellycoats structure to other materials, three pos-sible mechanisms for the action of the jellycoat may be identified. First, the apparentviscosity of the eggs of echinoids declinesas the rate at which they are sheared duringspawning increases. This reduction in vis-cosity with increasing shear rate (shear thin-ning) may in part be due to the structure ofthe jelly coats and their resultant non-newtonian nature. Second, experimentalevidence indicates that the jelly coat prefer-entially deforms under a compressive loadreducing the transmission of that load to theegg. Thirdly, the jelly (but not the fibers in thecoating) may deform in a nearly viscousmanner. In this case, the fibers may serve toprovide an elastic “backbone” to the layer,and remain in place to stiffen the outer layerof the egg. The composite structure of thejelly coat and the morphology of the fibrousnetwork are likely to be critical to all thesemechanisms.

S13.9THOMAS, F.I.M. University of SouthFLorida. Incorporation of an educationalcomponant into a research program: trialsand successes.

The CAREER program at NSF providesgrants for researchers early in their careers.In addition to a research program, these re-searchers are asked to develop programsdesigned to integrate their research with aneducational component. I was a recipient ofa CAREER award and subsequent

PECASE award in 1997. The research com-ponent of this grant is to examine the effectsof water velocity and community topogra-phy on transport and uptake of dissolvednutrients. We are using engineering mod-els, combined with field data to determinethe factors that control nutrient uptake by en-tire communities. We are also using stableisotopes to examine which members of thecommunity are involved in uptake. The edu-cation component of the program includesminority recruitment, high school and com-munity outreach programs. Developingthese educational programs has added achallenge to my early career development,but in general has been an addition to myresearch and to my entire laboratory. Themost successful and productive portion ofthe educational program has been the mi-nority recruitment program. Each summer 1- 2 undergraduates come to my laboratoryand participate in a research program. Thisprogram has been run in cooperation withTuskeegee University, Talladega College,and Florida A & M University. A total of sixstudents have participated in the programover the last 3 years. The program is nowfocused on developing continuing researchcollaboration with a laboratory at FAMU sothat the research experience can continuethroughout the academic year. The highschool and community outreach programhas evolved through time. At present we areworking with a high school physics teacherto develop a web based curriculum for highschool students that will also be accessiblefor community outreach.

S10.15 THOMPSON, J.N.*, NUIS-MER,S.L., University of California, Santa Cruz,Washington State University. Coevolutionand maladaptation.

Many of the most commonly cited ex-amples of exquisite adaptation are of co-evolved symbioses. As we learn more aboutthe coevolutionary process, however, it isbecoming increasingly evident that coevo-lution may also keep populations moderately

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maladapted much of the time. As a result,coevolving populations may only rarely oc-cupy adaptive peaks, because the selectivelandscape is under continual changethrough reciprocal selection on the speciesthemselves. These shifting patterns of co-adaptation are further shaped by the geo-graphic structure of most species. Selectionmosaics across landscapes and coevolu-tionary hotspots can favor different evolu-tionary trajectories in different populations.The combined action of gene flow, randomgenetic drift, and local extinction of popula-tions may then continually remold these lo-cal patterns, creating a geographic mosaicin the degrees of maladaptation found withinlocal interactions. Recent mathematicalmodels of the geographic mosaic of coevo-lution suggest that complex mosaics of mal-adaptation are a likely consequence of spa-tially structured species interactions. Thesemodels indicate that the spatial structure ofmaladaptation may depend upon the typeof coevolutionary interaction and the under-lying selection mosaic. By maintaining localpolymorphisms and driving the divergenceof populations, coevolution may producespatial patterns of maladaptation that are asource of ongoing innovation and diversifi-cation in species interactions.

58.3 THOMPSON, J.T., University of NorthCarolina, Chapel Hill. The ontogeny of squidmantle structure and function.

The mantle of cephalopod molluscs iscomposed of a complicated arrangement ofseveral different muscle and connective tis-sue components. Much is known aboutmantle structure and function in adult squid.However, significant alterations in mantle or-ganization occur during ontogeny that mayentail significant changes in mantle function.To understand the functional implications ofontogenetic changes in mantle morphology,I studied mantle connective tissue arrange-ment and mantle kinematics in Oval Squid,Sepioteuthis lessoniana. In the mantle, thefiber angle of collagen fibers in intramuscu-lar fiber system (IM) 1 and IM-2 was lowestin hatchling squid and increased exponen-tially during growth in squid up to 15mmdorsal mantle length (DML). In squid largerthan 15mm DML, IM-1 and IM-2 fiber angles

did not change significantly. A simple modelof mantle function based on IM collagen fi-ber arrangement predicts that the amplitudeof mantle movement during jet locomotionwill be highest in hatchling squid and willdecline with growth. Video records of es-cape jet behavior in tethered S. lessonianasupported the ontogenetic change in mantlekinematics predicted by the model. Duringthe escape jet, mantle hyperinflation andmantle contraction were greatest in newlyhatched animals and decreased exponen-tially during growth in squid up to 15mmDML. Mantle hyperinflation and contractiondid not change significantly in squid largerthan 15mm DML.h

28.2 THOMPSON,E.N.*, BIK-NEVICIUS,A.R., Ohio University, Athens. A biomechani-cal analysis of the development of the mas-ticatory apparatus of Monodelphisdomestica.

While several studies have found differ-ences in the craniofacial configurations ofjuvenile and adult mammals, how these dif-ferences affect masticatory process has beenpoorly explored. The present study evalu-ates the masticatory apparatus in an onto-genetic series of short-tailed opossums(Monodelphis domestica) using a biome-chanical model of the jaw developed byGreaves’(1978. J. Zool. Lond. 184: 295). Lon-gitudinal data on skull and upper jaw pa-rameters were obtained using radiographs.Results suggest that the occlusal area rep-resenting maximal bite force production (Re-gion II) is limited in juveniles and increasesinto adulthood. This increase appears to beassociated not only with posterior molar erup-tion but with changes in the configuration ofthe entire skull as well.

P1.40THURMAN, C.L.* University of North-ern Iowa, Cedar Falls. Variance in osmo-regulation among sympatric fiddler crabs,genus Uca, from Texas.

Osmoregulatory capabilties were mea-sured in five species of fiddler crabs fromeight coastal locations in Texas. Specimenswere placed in finger bowls containing 50mls of water ranging in osmolarity from 50 to3450 mOsm (2 to 110 ppt). Survivorship wasrecorded for each species. After 3 to 5 days

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of exposure, the osmolarity of a hemolymphsample was estimated using a Wescor 5520Vapor Pressure Osmometer. Uca rapax andU. panacea were most hardy over a widerange of media osmolarities. Uca spinicarpawere limited to surviving in media below1400 mOsm (45ppt). Uca subcylindrica andU. longisignalis were intermediate in sur-vival. U. panacea, U. sub-cylindrica and U.rapax were equivalent in their osmoregula-tion between 50(2ppt) and 3200 mOsm(100ppt). U. longisignalis lost it’s ability toregulate above 2200 mOsm (70ppt) whileU. spinicarpa ceased to regulate above 1200mOsm (40ppt). Among the five species, onlyU. longisignalis exhibited a variance in regu-lation related to site of collection. Thesephysiological capabilities correlate with thesalinity characteristics of the habitats typi-cally occupied by each species.

70.5 TILDEN, A.R.*, SCHWARTZ, J.,MCGANN, L., Colby College. Influence ofmelatonin on hemolymph metabolites in thefiddler crab Uca pugilator.

Melatonin levels were measured in theeyestalks of fiddler crabs (Uca pugilator)acclimated to a LD 12:12 photoperiod, con-stant dark, and constant light. Melatonincycled with a photophase peak during theLD 12:12 photoperiod. The cycle persistedin constant dark and constant light, with sig-nificantly greater melatonin production inconstant light. These results are contrary tothe scotophase melatonin peaks observedin most other organisms but may reflect ageneral crustacean phenomenon. We alsostudied the influence of melatonin onhemolymph glucose and lactate levels in fid-dler crabs. Crabs were acclimated to a LD12:12 photoperiod and were injected withmelatonin at the onset of light. Hemolymphsamples were taken every three hours over24 hr, and glucose and lactate were mea-sured simultaneously with enzymatic assays.In intact crabs, glucose and lactate levelscycled, with peaks in both occurring duringearly and late photophase. Melatonin shiftedboth glucose and lactate cycles, with onepeak occurring closer to mid-photophase.Glucose did not cycle in eyestalk-ablatedcrabs, and overall lactate levels were lowerthan in intact crabs. Melatonin injection

caused a delayed hyperglycemic responsein eyestalk-ablated crabs with a less pro-nounced but similar effect on lactate levels.Melatonin may be involved in the synchro-nization of hemolymph metabolite levels withactivity patterns, an influence that may notinvolve eyestalk factors.

P2.76TOBALSKE, B.W.*, BIE-WENER, A.A.,ZIMMERMAN, B.B., Harvard University,Cambridge MA and University of Portland,Harvard University, Cambridge MA, Univer-sity of Portland, OR. Scaling of takeoff me-chanics in doves (Columbidae).

Takeoff ability is considered to be of cen-tral importance to the ecology and evolutionof animal flight, yet few studies have exam-ined the magnitude and timing of groundreaction forces during takeoff in flying birds.Predictions of takeoff ability suggest that: 1)peak accelerations during maximum take-off should scale negatively with increasingbody mass and 2) initial air velocity is inde-pendent of body mass. To test these predic-tions, we studied takeoff mechanics in threespecies of doves (Columbidae) that variedin body mass from 40 to 492 g. The birdsinitiated flight while standing on a force platethat enabled measurement of vertical andhorizontal ground reaction forces. After take-off, the birds ascended nearly vertically andlanded on a perch 2 m above the force plate.Force recordings were sampled at 500 Hz;simultaneous high-speed video (250 Hz)was obtained for analysis of wing and bodykinematics. Among the three species, thelegs contributed proportionally more than thewings to flight velocity at the start of the sec-ond downstroke. Peak acceleration de-creased proportional to the -0.08 power ofbody mass while takeoff velocity scaled pro-portional to mass to the 0.11 power. Theseresults support prediction 1 but not predic-tion 2. Similar scaling patterns are reportedfor jump performance in terrestrial animals.Average takeoff speed among dove speciesranged from 2.0 to 2.7 m/s, which highlightsthat at no point during takeoff were the wingsused at 0 m/s, the speed at which the powercost for flapping flight is highest. (NSF IBN9923699)

54.1 TOMANEK, L.*, SOMERO, G.N.,

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Stanford University, Pacific Grove. Heat-shock protein (hsp) 70 and promoter se-quences in species of the genus Tegula fromwidely differing thermal environments.

Marine gastropod species of the genusTegula occupy widely differing thermal en-vironments along the transition from the sub-to the intertidal zone. Corresponding withthese differences in vertical zonation are find-ings that the mid-intertidal T. funebralis showsa higher thermotolerance as well as a higherinduction and upper temperature of hsp syn-thesis, following acclimation to a commontemperature than do the two subtidal spe-cies, T. brunnea and T. montereyi. In addi-tion, in nature T. funebralis experiences tem-peratures that induce the stress responsemore frequently than the two subtidal spe-cies, which suggests that it activates thestress response more frequently under invivo conditions. Previous research has alsoshown that T. funebralis activates the stressresponse and recovers much faster from astress-inducing temperature exposure typi-cal for the mid-intertidal than the subtidal T.brunnea. To investigate the molecularmechanisms that underlie these differencesin stress response activation we sequencedthe promoter region and the complete cyto-solic hsp70 mRNA of T. funebralis. The pro-moter region contains a heat-shock element(HSE), which is a binding region for the heat-shock factor. By binding to the HSE, heat-shock factor activates transcription of hspgenes. A comparison of 65% of the hsp70gene among all three congeners showsthree non-synonymous changes in aminoacid primary structure in the far C-terminalregion only. This region may be important inthe conversion of active hsp70 monomersinto inactive oligomers following a stress re-sponse. We are currently elucidating theremaining hsp70 and promoter sequencesfor T. brunnea and T. montereyi.

P3.45TOSTE, A.M.*, BAUER, D.K.,TSUKIMURA, B., California State Univeersity,Fresno. Reproductive properties of the Chi-nese mitten crab Eriocheir sinensis.

The Chinese mitten crab, Eriocheirsinensis, invaded Central California’s wa-terways and expanded into the San Joaquinwater system. Our focus is to study their re-

productive capacity. We first investigated aportion of their reproductive cycle and foundovarian weights doubled from September(6.0 ± 0.4g) to October (11.3 ± 0.42g), thenremained constant from October throughFebruary. The gonadosomatic index (GSI)doubled from 4 ± 0.27% to 8 ± 0.25% duringthe same time. We isolated and character-ized the yolk protein, vitellin (Vn). UsingFPLC, the molecular mass (MM) of Vn was618 kDa. SDS-PAGE revealed Vn is com-posed of four subunits 129 ± 1.8 kDa, 115 ±2.5 kDa, 105 ± 1.5 kDa, and 95 ± 1.7 kDa inMM. Digestion with PNGase-F reducedthese subunits into three subunits, 119±3.6,102±2.5, and 95±3.0 kDa indicating N-linked glycosylation of the two larger Vn sub-units. NANase II and O-Glycosidase DSshowed no quantifiable effect. Anti-Vn antis-era was developed against native Vn. West-ern blots were used to demonstrate antiseraspecificity. ELISA’s, using a 1:14000 antis-era dilution and having an effective range of1- 300 ng, were developed to measurehemolymph concentrations of yolk proteinsand to compare hemolymph concentrationswith the GSI.

P1.32TOWLE, D.W., Lake Forest College,IL and Mt. Desert Island Bio. A proposal toestablish CRABinfo, a user-directed data-base for crustacean bioinformatics.

The crustacean research community isinvited to respond to a proposal to establishthe Crustacean Research And Bio-INFOrmatics database, CRABinfo. Modeledafter successful internet projects such asFlyBase and the Zebrafish Information Net-work (ZFIN), CRABinfo seeks to support andenhance research activities on crustaceans,particularly studies at the molecular level. IfCRABinfo can be funded and implemented,genomic DNA and cDNA sequences fromcrustacean species will be collected in apublicly accessible database, with links toGenBank and other generalized databases.The entries will be annotated by a curator,adding such information as bibliographicrecords, multiple alignments, and links tohomologous sequences. Links will be in-cluded to laboratories and individuals par-ticipating in constructing the database. Oneof the potentially most useful applications of

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the database will be to serve as a clearinghouse for molecular reagents such as cDNAand genomic libraries, RNA and DNAprobes, and PCR primers, indicating whereinvestigators may obtain the materials. Ascrustacean species become targets for ge-nomic sequencing and expressed sequencetag analysis, these data will be added toCRABinfo. The database will be providedwith a web-based search page to which anyinvestigator may obtain access. User-di-rected entry of data will be accomplished byregistered users as well as the databasecurators. Please email your gestures of sup-port and suggestions for development ofCRABinfo to [email protected]. Supported byNSF (IBN-9807539).

49.2 TRACY, C. R.*, DIAMOND, J., Univer-sity of Wisconsin - Madison, UCLA. Altitudi-nal variation in effects of hibernation andfeeding on nutrient uptake in chuckwallas(Sauromalus obesus: Iguanidae).

We examined the effects of hibernationand fasting on intestinal glucose and pro-line uptake rates of chuckwallas. These liz-ards show dramatic geographic variation inbody size and growth rate that parallels analtitudinal gradient in our study area. At lowaltitude, food is available only for a short timeduring the spring; at high altitude, food mayalso be available during summer and au-tumn, depending on rainfall conditions in agiven year. We hypothesized that low-alti-tude lizards with a short season of food avail-ability would show more pronounced regu-lation of gut size and function than high-alti-tude lizards with prolonged or bimodal foodavailability. Hibernating lizards from bothareas had significantly lower uptake ratesper milligram intestine for both nutrients, andthey had lower small intestine mass thanactive lizards. This results in significantlylower total nutrient uptake in hibernatinganimals compared to active ones. Lizardsfrom low altitudes with a short growing sea-son also showed a greater increase in bothuptake rates and small intestine mass whenactive versus when hibernating, comparedto those from high altitudes with longer grow-ing seasons. Thus, compared to those fromlong season areas, lizards from short sea-son areas have equal uptake capacity dur-

ing hibernation, but much higher uptake ca-pacity while active and feeding. This patternof regulation of gut function may be an adap-tive response. In areas with a short season,those lizards which can extract nutrientsquickly and then reduce the expensive gutwill be favored; in areas where food may beavailable later in the year, those lizards thatmaintain a relatively active gut would be fa-vored.

20.1 TRAPIDO-ROSENTHAL, H.G.*,ZENGLER, K., RITTER, J.E., Bermuda Bio-logical Station for Research, Diversa Cor-poration, Diversa Corporation. Multiple spe-cies of archaea, cyanobacteria, andeubacteria live in association with the spongeChondrilla nucula.

Marine sponges have been the subjectsof natural products chemists’ investigationsfor many years, and have been the sourcesfrom which novel chemicals with interestingproperties have been isolated. Many marinesponges harbor large populations of symbi-otic bacteria, an observation which has ledto the thought that these bacteria may be theorganisms responsible for a significant frac-tion of the interesting chemicals that havebeen found in sponge homogenates. At-tempts to culture these symbionts prior tofurther taxonomic and chemical studies havenot always been successful. We are investi-gating the biodiversity of bacterial popula-tions that live in association with spongesusing techniques that allow us to bypass theculturing step. The sponge Chondrilla nuculawas collected from shallow depths inHarrington Sound, frozen at ñ70 ƒC, andthen mechanically homogenized in five vol-umes of sterile, calcium- and magnesium-free artificial seawater (ASW). Thehomogenates were subjected to multiplerounds of centrifugation on Percoll/ASW gra-dients (15% v/v). The resulting bands of cellswere collected, the cells were lysed, and the16S ribosomal RNA genes present in thelysate were amplified by means of PCR,using primer sets designed to identify thesegenes from eubacteria, cyanobacteria, andarchaea. The amplification products werecloned, and their sequences determined andcompared to 16S sequences in GenBank.The results indicate that 15 species of

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eubacteria, 7 of cyanobacteria, and 4 ofarchaea, were living in association with C.nucula. Molecular methods have the poten-tial to enhance our understanding of the na-ture of sponge-bacteria relationships at boththe quantitative and qualitative levels.

P1.24 TRINACHARTVANIT, W., DEVRIES,A.L., CHENG, C.- H. C., University of Illinois,Urbana-Champaign. Antifreeze glycopro-teins (AFGPs) are secreted into the diges-tive tract from the pancreas in Antarcticnotothenioid fishes.

Pancreatic tissues in teleost fishes arediffuse unlike other vertebrates. In the largeAntarctic notothenioid fish Dissostichusmawsoni a small reservoir exists at the ter-minus of the pancreatic tissue duct systemin the tissue surrounding the common bileduct. Freezing-melting point (i.e. antifreezeactivity) analyses of pancreatic fluid samples(0.2 ml to 1.0 ml) from this reservoir indicatethe presence of high levels of antifreeze pro-tein. Polyacrylamide gel electrophoresis ofpurified antifreeze from pancreatic fluidshows the presence of the same eight sizesof antifreeze glycoproteins (AFGPs) foundin the blood except the large AFGPs 1-5occur in much lower abundance. The intes-tinal fluid has a similar AFGP profile as thepancreatic fluid, indicating the intestinalAFGPs came from the pancreatic fluid. Theantifreeze activity of the intestinal fluid ishigher than that of the pancreatic, indicatingthat the AFGP concentrations in intestinalfluids are higher than in the pancreatic flu-ids. Since AFGPs in the intestinal fluid ap-pear to be neither digested nor reabsorbed,the higher AFGP levels in the intestinal fluidare likely due to concentration of AFGPs asdigested food and water are absorbed.

18.4 TROWBRIDGE, C.D.* HIRANO, Y.J.,Oregon State University, Newport, ChibaUniversity, Kominato, Japan. Marine special-ist herbivores on high-diversity shores: eco-logical notes of Japanese ascoglossan (=Sacoglossan) opisthobranchs.

Most marine specialist herbivores belongto the molluscan order Ascoglossa, a groupof suctorial sea slugs that show intriguingparallels with phytophagous insects. We in-vestigated the ecology of ascoglossans in a

region of high species richness: the temper-ate rocky shores of Sagami Bay, NE Japan.The wealth of taxonomic descriptions aboutJapanese sea slugs contrasts with the mea-ger ecological information. Based at MisakiMarine Biological Station (University Tokyo),we investigated three ascoglossan assem-blages: (1) Placida dendritica, Elysiatrisinuata, and Elysia setoensis on Codiumspp., (2) Ercolania boodleae, Aplysiopsisminor, and Elysia nigrocapitata in high inter-tidal pools associated with filamentous greenalgae, and (3) Stiliger berghi associated withpolysiphonous red algae. The small (<15mg) Placida dendritica was most abundanton subtidal C. fragile whereas the large(<800 mg) Elysia trisinuata was most frequenton the encrusting C. arabicum. The pool-dwelling Ercolania boodleae formed high-density populations of small animals (<10mg) whereas the other two sympatric spe-cies were sparsely distributed and consid-erably larger. Finally, the very small (<4 mg)Stiliger berghi occurred on red algae epi-phytic on subtidal Codium. The feedingspecificity of the Codium-associated slugswas partially elucidated: recent feeding his-tory of the slugs and age and physiologicalcondition of the algae influenced slugs' host-plant choice. Given the high species rich-ness of ascoglossans on NW Pacific shores,interspecific interactions may influence co-existence among these sympatric species.Additional ecological study of these speciesis clearly merited.

70.6 TSAI, P.-S.*, MALDONADO, T.A., PAK,T.R., ZHANG, L., University of Colorado,Boulder, University of Colorado, Boulder,University of Colorado, Boulder, Universityof Connecticut, Storrs. Characterization of aGonadotropin-Releasing Hormone Systemin an opisthobranch mollusk, Aplysiacalifornica.

Gonadotropin-releasing hormone(GnRH) is a neurohormone crucial for theregulation of reproductive and neural func-tions in vertebrates. Recent discoveriesof GnRH immunoreactivity (IR) in a num-ber of invertebrates raised the possibilitythat GnRH may be an ancient moleculethat had arisen before the emergence ofPhylum Chordata. We previously demon-

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strated the presence of a GnRH-IR similarto the mammalian (m) and tunicate I (tI)forms of GnRH in the hemolymph andovotestis of an opisthobranch mollusk,Aplysia californica; however, the presenceof GnRH in Aplysia central nervous sys-tem (CNS) could not be detected with theavailable antisera against various formsof chordate GnRH. In the present study,we generated an antiserum against a syn-thetic tI-GnRH analogue (97575). Thisantiserum cross-reacted strongly with na-tive tI-GnRH and also detected GnRH-IRin extracts of ovotestis and hemolymph.Immunocytochemical analysis revealedthat this antiserum detected strong GnRH-IR in defined neurons of Aplysia CNS, withthe greatest number of GnRH-IR neuronspresent in pedal and pleural ganglia. Insummary, we have identified a GnRH-IRvery similar to tI-GnRH in the CNS,hemolymph and ovotestis of Aplysiacalifornica. In view of our previous findingthat vertebrate GnRH can alter the electri-cal activity of Aplysia neurons, the possi-bility exists that this GnRH-IR may be afactor released from the CNS and ovotes-tis into circulation to alter neural functions.(Supported by NSF Grant IBN-9996398 toPST).

P3.43 TUBERTY, S.R.*, NATES, S.F.,MCKENNEY Jr., C.L., University of WestFlorida, Pensacola, FL, NRC/US EPANHEERL-Gulf Ecology Division, Gulf Bree,US EPA NHEERL-Gulf Ecology Division,Gulf Breeze. Polyclonal antisera againstestuarine crustacean vitellins: a molecu-lar approach to reproductive endocrinol-ogy and toxicology.

In order to fully elucidate the action ofcrustacean hormones, or their agonists,on reproduction and vitellogenesis it hasbecome increasingly important to developsensitive assays that indicate a stimula-tory or inhibitory effect on easily measuredendpoints. Because of the relative abun-dance of vitellin in crustacean yolk andthe ease with which it can be isolated, vi-tellin makes an excellent model for study-ing the mechanisms that control and regu-

late reproduction. With this in mind, adultfemale Lepidophthalmus louisianensis,Palaemonetes pugio, Rhithropanopeusharrisii, Americamysis (Mysidopsis) bahia,and Uca panacea were collected from es-tuarine localities in Santa Rosa Sound,Gulf Breeze, Florida during late spring andsummer of 1999. Vitellin was purified fromeach crustacean and used to immunizerabbits for polyclonal antibody production.Specificity of each antisera was testedagainst their respective vitellins by West-ern blotting. The antisera will be used todevelop enzyme-linked im-munosorbentassays for determination of hemolymphvitellogenin and egg vitellin concentra-tions. These assays could be used to de-termine effects of endogenous hormoneson the rate or onset of vitellogenesis. Inaddition, these assays would be valuabletools in determining the effects of insectjuvenile hormone agonists on reproduc-tion and egg maturation.

S7.13TURBEVILLE, J. M., University of Ar-kansas. Recent progress in Nemertean bi-ology: phylogeny, development, ecology.

Phylum Nemertea contains approxi-mately 1000 species of unsegmented wormsthat possess an eversible proboscis. Thephylum has a global distribution and in-cludes marine, freshwater and terrestrialspecies. Although relatively common, nem-erteans have been understudied. However,in recent years significant advances in nem-ertean biology have been made and contri-butions to three areas will be reviewed: 1)phylogeny, 2) development and 3) ecology.Nemerteans are generally considered to beprimitive acoelomate bilaterians most closelyrelated to platyhelminths, and their HOXgenes recently have been examined to gaininsight into the evolution of these regulatorygenes in Bilateria. Nevertheless, their phy-logenetic position remains uncertain. Onerecent cladistic analysis of morphologicalcharacters places nemerteans in a spiraliancoelomate clade, whereas another supportsa Nemertea + Platyhelminthes clade. Theseconflicting phylogenies result from differenta priori interpretations of nemertean bodycavities and other morphological features.Analyses of 18S rDNA sequences suggest

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that nemerteans are most closely related tocoelomate “lophotrochozoans”. Preliminarycomparisons of mitochondrial gene rear-rangements support monophyly of spiraliansinclusive of playthelminths and nemerteans,but the placement of nemerteans among thespiralians is unresolved. Additional molecu-lar and morphological characters are cur-rently being evaluated for estimating nem-ertean relationships. Recent studies of nem-ertean development have clarified the ori-gin of mesoderm and larval structures, haverevealed differences in regulation betweendirect and indirect developing species andhave elucidated calcium dynamics duringfertilization. Progress in nemertean ecologywill also be addressed.

40.3 TURINGAN, R.G., Florida Institute ofTechnology. Functional and morphologicalbases of prey-capture performance in ma-rine-fish larvae.

A critical period, marked by a rapid de-cline in population size, occurs immediatelyfollowing yolk-absorption during the larvalphase of marine teleosts. Biotic and abioticfactors associated with mortality during thiscritical period have been identified, but thecausal link between these factors and mor-tality is not clearly understood. This studyexplores the link between development ofthe feeding mechanism and prey-captureperformance in larval red drum (Sciaenopsocellatus). Lower-jaw depression in reddrum larvae developed from a simplemechanism around first-feeding, driven bythe hyoid-mandible linkage (i.e., the hyoidstage), to a more complex mechanismaround metamorphosis, driven by the hy-oid- and opercular series-mandible linkages(i.e., the hyoid-opercular stage). This two-stage development of the feeding mecha-nism was associated with differences in feed-ing performance: (1) less than 50% of larvaefed during the hyoid stage whereas almostall larvae at the hyoid-opercular stage con-sumed prey; and (2) first-feeding larvae pre-ferred small and less elusive prey relative toconspecifics at metamorphosis, which pre-ferred larger and more elusive prey. Ourability to understand the functional relation-ship between development of the feeding

mechanism and prey-capture performanceenhances our ability to understand the un-derlying causes of mortality in larval fishes.

P1.16TWEEDIE, E.P.*, SHAFER, T.H., Uni-versity of North Carolina, Wilmington. Purifi-cation and characterization of mucin-like gly-coproteins from the cuticle of the blue crabCallinectes sapidus.

Two molecular species previously iden-tified as electrophoretic bands at 66 and 79kD in extracts from dorsal carpace cuticledisappear within a few hours after the moltin the blue crab, Callinectes sapidus. Dis-appearance of these bands occurs coinci-dentally with the onset of initial mineral depo-sition in the new cuticle exposed by molting.Identified as heavily glycosylated, mucin-likeproteins, these two molecular species havebeen purified to homogeneity by jacalin lec-tin affinity and gel filtration chromatographycolumns and SDS-PAGE. The species con-tain both N- and O-glycosidic linkages, asindicated by PNGase electrophoretic bandshifts, as well as affinity for jacalin and con-canavalin A lectins. Polyclonal antibodiesraised against the purified glycoproteinswere used in Western blot and immunohis-tochemical analyses of early postmolt cu-ticle. Western blots revealed similar post-ecdysial cuticle alteration (PECA) changesas those recorded in previous research;namely, a dramatic electrophoretic band shiftat one to two hours postmolt. Although anti-bodies demonstrated an affinity for epicu-ticular material in fluorescence-assisted his-tochemistry, they were not specific enoughto distinguish or localize the mucin-like pro-teins in cuticle sections. Amino acid se-quencing is being undertaken in order toraise more specific antibodies againstepitopes in the core polypeptide.

P1.5 TYLER, S.*, HOOGE M.D., Universityof Maine, Orono. Squeezing through tightspaces—functional morphology of muscu-lature of Gnathostomula armata.

Gnathostomulids live in fine-grained sedi-ments with pore sizes that are typicallysmaller than the diameter of their bodies.How they negotiate such spaces is some-thing of a mystery, but whole-mount prepa-rations of Gnathostomula armata stained with

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a phalloidin-linked fluorescent marker to re-veal its musculature under confocal scan-ning laser microscopy provides some clues.The musculature is unlike that of other soft-bodied meiofaunal phyla, being dominatedby longitudinal fibers that run the full lengthof the body and having circular fibers only inthe posterior half of the body. Conceivably,the strong circular muscles may be used topush the anterior body half through restrict-ing pores, and the longitudinal elements maythen pull the rest of the body through. Musclesof the pharynx visible in such preparationsare positioned to move the cuticularizedmouthparts in ways appropriate to scrapingup and grasping the bacteria and fungal hy-phae on which gnathostomulids are be-lieved to feed.

P2.64A TYTELL, E.D., ELLINGTON, C.P.,Department of Zoology, University of Cam-bridge. The vortex wake of the hawkmoth,Manduca sexta: simulation and Reynoldsnumber effects.

The vortex wake structure of the hawk-moth, Manduca sexta, was investigated us-ing a vortex ring generator. Based on exist-ing kinematic and morphological data, a pis-ton and tube apparatus was constructed toproduce circular vortex rings with the samesize and disc loading as a hovering hawk-moth. The artificial rings were shown to bequalitatively similar to the vortex wake ofactual hawkmoths. They were initially lami-nar, but developed an azimuthal wave in-stability and became turbulent. The initialimpulse and circulation was accurately esti-mated for laminar rings using particle imag-ing velocimetry (PIV); after the transition toturbulence, though, initial circulation wasgenerally underestimated. The underesti-mate for turbulent rings can be corrected iftransition time and velocity profile are accu-rately known, but this correction will not befeasible for experiments on real animals. Itis therefore crucial that the circulation andimpulse are estimated while the wake vorti-ces are still laminar. Based on the scaling ofring Reynolds number, hawkmoths and ani-mals with similar wingspan and wing beatfrequency are probably the largest for whichthe laminar period lasts long enough during

hovering. Thus, at low advance ratios, theymay be largest animals for which wake cir-culation and impulse can be accuratelymeasured.

S13.8UDOVIC, D., University of Oregon.Rethinking introductory biology: the work-shop biology project as a case study in cur-ricular reform.

Workshop Biology is one of many experi-mental approaches to teaching introductorycollege-level science that emerged duringthe 1990’s. The goal of this non-majors’course is to engage students in open-ended,interactive activities and projects designedto develop (1) studentsí understanding ofessential biological concepts, (2) their un-derstanding of the process of scientific dis-covery, and (3) their critical thinking skills.Overall, our desire is to improve students’abilities to make good decisions about im-portant personal and societal issues by fos-tering their ability to bring scientific knowl-edge and ways of thinking to bear on prob-lems whenever relevant. In this talk I will de-scribe the Workshop Biology philosophy, il-lustrate our approach, and discuss currentevidence that this approach and others likeit are effective in achieving their goals.

23.2 USHERWOOD, J. R., Florida StateUniversity, Tallahassee. Aerodynamics andenergetics of animal flight based on propel-ler models.

Recent work on flapping insect modelshas demonstrated the importance of a spiral'leading-edge vortex' created by dynamicstall and maintained by some aspect ofspanwise flow, for creating the lift requiredduring flight (Ellington et al., 1996; Dickinsonet al., 1999). This study uses propeller mod-els to investigate further the forces acting onmodel and real animal wings in 'propeller-like' rotation ('revolution'). The effects of cam-ber, twist, and leading-edge characteristicsare shown to be minor for model Manducawings. Force coefficients are derived forwings of animals ranging from mayfly toquail. Some aspect of the aerodynamics ofanimal wings in revolution, presumably theleading-edge vortex, results in high lift anddrag forces, and appears to be a robust phe-nomenon. A consistent relationship be-

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tween vertical and horizontal forces, and theangle of attack, is described. This is inde-pendent from local flow conditions, and anew method for estimating power require-ments is developed. The power require-ments derived for hovering are higher thanthose previously predicted, but are consid-ered upper estimates.

7.1 VAGELLI, A.A., N.J. Academy forAquatic Sciences. New observations on theasexual reproduction of Aurelia aurita(cnidaria, scyphozoa) with comments on itsdaptative significance.

A new reproductive mechanism has beenobserved in scyphistomae of Aurelia aurita.It is termed gemmation and it is referred toas an asexual mode of reproduction in whichscyphistomae produce small and mostlyspherical masses of cells called gemmae.These structures are generated internally byextrusion of the body wall tissue. In contrastto the budding process, gemmation pro-duces ramets that do not develop adult scy-phistoma morphology prior to their release,and they only do so after passing through afree-swimming period that lasts severalweeks. In addition, a new budding processin A. aurita is reported. It is characterized bythe external production of free-swimmingbuds, which also pass through a planktonicstage before settlement and metamorpho-sis occurs. A description of A. aurita lifecycle is presented, including comments onits various modes of asexual reproduction,larval development, and their adaptativesignificance.

57.1 VALVERDE, R.A.*, DENVER, R.J.,University of Michigan, Ann Arbor. Molecu-lar evolution of the corticotropin-releasinghormone binding protein

Corticotropin-releasing hormone (CRH)is the primary neuroendocrine mediator ofthe stress response in vertebrates. CRH isknown to regulate appetite, locomotion, re-productive processes, and development,either by acting within the central nervoussystem or by functioning as ahypophysiotropin, regulating the productionof adrenal steroids and thyroid hormone. Ahigh affinity, specific CRH binding protein

(CRHBP) has been identified in severalmammalian species and in the amphibianXenopus laevis. The protein exhibits exten-sive structural and functional conservationamong the taxa studied to date. The CRHBPis thought to regulate the bioavailability ofCRH by competing for binding with CRH re-ceptors. Using a crosslinking, competitivebinding assay we report the detection of theCRHBP in the brain of an agnathan fish thesea lamprey (Petromyzon marinus), a teleostfish, the tilapia (Oreochromis mossambicus),a chelonian reptile, the red-eared slider turtle(Trachemys scripta), and a bird, the chicken(Gallus domesticus). The CRHBP in thesetaxa reversibly binds [125I]-Xenopus CRH asdoes the frog binding protein. In an effort tounderstand the molecular evolution of thiskey neuroendocrine regulatory protein weare currently cloning and sequencingCRHBP cDNAs from several vertebrates. Ourcurrent data show that the CRHBP is a phy-logenetically ancient protein and suggestthat the regulatory role of CRHBP for theCRH peptide arose early in animalevolution.(Supported by NSF grantIBN9974672 to RJD; RAV was supported bya NIH training grant administered by theCenter for Organogenesis, University ofMichigan)

16.5 VAN CLEEFF, J.*, BLACHE, D.,MARTIN, G., University of Western Aus-tralia. Early castration of male emus(dromaius novaehollandiae) reduces theirfeed efficiency and attenuates vernal fat-tening without impairing appetite.

The emu responds to increasing photo-period with an increase in appetite and fatdeposition. This response is normally de-layed until breeding season hormones,stimulated by short days, have been clearedfrom the system, about 6 weeks after theWinter Solstice in the case of non-incubat-ing males. We investigated the interactionsbetween testosterone, feed intake and ver-nal fatttening in male emus fed ad libitumand maintained outdoors in a Mediterra-nean type environment (Perth, Australia).Emus castrated as 8-week-old chicks grewnormally but in adulthood failed to undergovernal fattening to the same extent as intact

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contemporaries, and lost less weight in Win-ter. Thus, live weight change was significantlyattenuated in Castrated emus. Maximumsummer weight was 43.1 ± 1.4 kg for Cas-trated emus, and 49.2 ± 1.6 kg for Intactemus. In Winter, Castrated emus lost 9% fromthe maximum live weight of the previoussummer, compared to 18% for Intact emus.Annual feed intake was similar between In-tact and Castrated emus, but intake was high-est in Winter for Castrated emus and high-est in Spring for Intact emus. Castrated emuscan respond to increasing photoperiod verysoon after the Winter Solstice with increasedintake and fat deposition, but their ability todeposit fat is severely impaired. Testoster-one appears to be necessary for normal feedefficiency and conversion of consumed feedto fat deposits in Spring and Summer in theemu.

33.6 VAN VOORHIES, W. A., New MexicoState University. Broad oxygen tolerance inthe nematode Caenorhabditis elegans.

I studied the effects of oxygen tensionsranging from 0 to 90 kPa on the metabolism,movement, and survivorship in the free-liv-ing, soil nematode Caenorhabditis elegans.C. elegans requires oxygen to develop andsurvive. However, it can maintain a normalmetabolic rate at oxygen levels of 3.6 kPaand has near normal metabolic levels atoxygen levels as low as 2 kPa. The ability towithstand low ambient oxygen levels ap-pears to be a consequence of the small bodysize of C. elegans which allows diffusion toreadily supply oxygen to cells without re-quiring any specialized respiratory or meta-bolic adaptations. Thus, the small size of thisorganism pre-adapts C. elegans to living insoil environments that commonly becomehypoxic. Movement in C. elegans appearsto be of relatively minor metabolic cost. Dif-ferent developmental stages of C. elegansare able to withstand up to 24 hrs of anoxiawithout major mortality. Longer periods sig-nificantly increased mortality, particularly foreggs. Remarkably, long-term exposure to100% oxygen had no effect on C. elegansmetabolic rate and populations were able tosurvive for a least 50 generations in 100%(90 kPa) oxygen. Such hyperoxic conditionsare fatal to most organisms within a short

period.

P3.30VAN WINKLE, D.H.*, BLACKSTONE,N.W., Northern Illinois University Ontoge-netic changes in competitive behavior &ability in colonial hydroids.

In controlled laboratory experiments, colo-nies of Podocoryna carnea (PC) typicallyovergrow and kill colonies of Hydractiniasymbiolongicarpus (HS). Generally, theseexperiments have used colonies grown fromtissue explants surgically removed frommature colonies taken from natural popula-tions. Recent experiments comparing inter-specific bouts among juveniles and thoseamong explants taken from mature coloniesreveal that both the behavioral characteris-tics and outcomes of competition are signifi-cantly different. Among juveniles, HS colo-nies exhibit directional growth toward PCand more readily produce nematocyte-richhyperplastic stolons than PC. Nevertheless,PC can still overcome HS if it initially growsaway from the contact zone and subse-quently outgrows HS. Overall, HS juvenilesdestroyed their PC counterparts in more than35% of competitive bouts on limited sub-strata, while mature PC colonies dominatedtheir HS counterparts in all similar encoun-ters. In the field, both species occur on gas-tropod shells inhabited by hermit crabs. Onthese shells, competition among young colo-nies is a common phenomenon. The samefactors that lead to differential larval settle-ment over the shell surface likely also leadto food gradients. The directional growth po-tential of juvenile HS colonies leading to theoccupation and defense of these nutrient-rich zones may thus provide a significantadvantage owing to increased growth ratesin early ontogeny. The recently observed be-havior and relative success of competingjuvenile HS colonies may in part explain theconsiderably greater abundance of this spe-cies in natural habitats relative to PC.

S3.9 VANDERLEEUW, A.H.J.*, BOUT, R.G.,ZWEERS, G.A., Leiden University, Instituteof Evolutionary and E. Control of the cranio-cervical system during feeding in birds.

The avian neck is a complex, kinemati-

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cally redundant system, that plays a roleduring i.a. food prehension and manipula-tion. The kinematic redundancy is resolvedby movement principles, e.g., Fowl movetheir necks according to a geometric prin-ciple that maximizes rotation efficiency. Themovement pattern shows large rotations insome joints, while keeping the other verte-brae more or less as straight bars. Water-fowl show a pattern of successive, rather thansimultaneous rotations, in the rostral part ofthe neck. A kinematic model shows that thegeometric principle only produces a Water-fowl-like pattern if a constraint on the move-ment of the caudal vertebrae is introduced.The constraint is related to the amount ofstretch in the long dorsal neck muscles,which have a different configuration in Wa-terfowl. To investigate whether the differencein movement pattern result from differencesin either anatomy or neuromotor patterns,the EMG of neck muscles was comparedbetween Mallard and Chicken for drinking,pecking and inertial feeding. The resultsshow large differences: 1. In mallards, con-siderable overlap is found in the activity ofantagonist, but not in chickens. 2. Dorsalmuscles in the rostral part of the neck areactivated successively in mallards, ratherthan simultaneously as in chickens. 3. In mal-lards, ventral and dorsal muscles are activeduring the backward and forward movementof inertial feeding respectively, but the re-verse is found in chickens. We conclude thatthe difference in movement patterning be-tween Chicken and Mallard results from adifference in the control system of the neck,which may have evolved as an adaptationto aquatic feeding in Waterfowl, but is alsoevident in various movements above thewater surface and on land.

48.4 VANHOOYDONCK, B.*, VAN DAMME,R., AERTS, P., University of Antwerp (U.I.A),Belgium. Trade-offs in the evolution of loco-motor performance: are speed and staminacorrelated in lacertid lizards?

Morphological and physiological consid-erations suggest that sprinting ability andendurance capacity put conflicting demandson the design of an animal’s locomotor ap-paratus, and therefore cannot be optimised

simultaneously. To test this hypothesis, wecorrelated size-corrected maximal sprintspeed and stamina of 12 species of lacertidlizards. Both raw species means and phylo-genetically independent contrasts of sprintspeed and stamina showed a significantnegative relationship, giving support to theidea of an evolutionary trade-off betweenthe two performance measures. To test thehypothesis that the trade-off is mediated bya conflict in morphological requirements, wecorrelated both performance traits with snout-vent length, size-corrected estimates of bodymass and limb length, and relative hind limblength (the residuals of the relationship be-tween hind and fore limb length). Fast run-ning species had hind limbs that were longcompared to their fore limbs. None of theother size and shape variables showed asignificant relationship with speed or endur-ance. We conclude that the evolution of sprintcapacity may be constrained by the need forendurance capacity and vice versa, but iden-tification of the design conflict underlying thistrade-off is needed to close the case.

P2.54VATNICK, I.*, GRANT, B., WidenerUniversity. Principles of design for a re-search-centered biology curriculum.

In the last decade, undergraduate sci-ence education has undergone a quietrevolution emphasizing opportunities forstudent-directed original inquiry as thecurriculum. Opportunities to conduct genu-ine investigations are important becausethey teach students how science is actu-ally done and thereby they learn by doingit. However, entering students lack suffi-cient confidence, organizational skills, andcontent background for open-ended stu-dent-directed investigations as freshmen.Our solution is to design a program thatincrementally introduces more open-ended inquiries. The initial task in the lad-der is to infuse research inquiry experi-ences in the laboratory portions of ourfreshmen and sophomore requiredcourses that will at least enable studentsto understand the process of knowledgeconstruction. In addition we hope thatthese experiences will stimulate studentsto become involved in substantive re-

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search collaborations with faculty as earlyas the freshmen or sophomore years. Ourupper division curriculum allows studentsto concentrate on their areas of interestand is flexible enough to allow students toconduct research projects in addition tocourse work. We discuss some of the keyissues (e.g. pedagogies, facilities, and thereward system) that arise while transform-ing traditional curricula to a research- richcurriculum.

50.5 VESS, T.J.*, FREDERIK, H.N., DukeUniversity. Unraveling the evolution of colorpattern: exploring sources of variation inCoccinellid spots.

Development is the vehicle by whichgenetic and environmental inputs affectmorphology and is critical for accurate in-terpretation of the evolution of Coccinellidcolor pattern. Ladybug spots are of par-ticular interest because the genetics andthe distributions of melanic and non-mela-nic forms are well charactarized yet theexisting variation is not fully explained. Inaddition, many of the selective forceswhich act on spotting pattern have beenidentified. To date, studies have focusedon the differences among morphs in poly-morphic species, with little to no attentionpaid to sources of variation within a morphor in monomorphic species. Adult Harmo-nia axyridis, an extremely polymorphicspecies, and Epilachna varivestis, a mono-morphic species were reared at three tem-peratures and their spots measured to de-termine the degree of phenotypic plasiticyin expression of spots. Both speciesshowed significant levels of plasticity anda sexual dimorphism in spot expression.

10.3 VEZINA, F.*, SALVANTE, K.G., WILL-IAMS, T.D., Simon Fraser University, Burnaby,B.C. Canada, The metabolic cost of yolk pre-cursor production.

The metabolic cost of egg productionin birds is poorly understood. Previous re-sults with European Starlings (Sturnus vul-garis) suggested that physiological adjust-ments, namely production of the yolk pre-cursors, vitellogenin (VTG) and yolk-tar-geted very-low density l ipoprotein(VLDLy), may be responsible for an in-

crease in resting metabolic rate (RMR)during follicular development and egg pro-duction. To test this hypothesis we admin-istered 17-beta estradiol (E2) to male andfemale zebra finches (Taeniopygia guttata)to stimulate yolk precursor production innon-reproductive birds and measure itseffect on RMR. The metabolic rates of shamand E2-treated birds were measured be-fore and after the E2 administration pe-riod (four daily injections). E2 administra-tion resulted in an increase in plasma VTGlevels, as well as an increase in oviductmass, but to levels lower than natural re-productive state. RMR was not affected byE2 treatment, nor were plasma levels ofVLDL or ovary mass. Resting metabolicrate was not related to oviduct mass andwas repeatable when comparing beforeand after treatment.

S15.9VLECK, C.*, VLECK, D., Iowa StateUniversity, Ames. Physiological condition andreproductive consequences in Adelie pen-guins.

Animals must make ‘decisions’ (e.g. whenor whether to breed, the effort to put into abreeding episode) by integrating physiologi-cal, environmental and social inputs. Thisintegration can only be studied in a field con-text. Physiological measurements that pro-vide reliable predictors of animalsí reproduc-tive decisions will aid in identifying criticalinput variables and in predicting and poten-tially managing reproductive success innatural populations. Candidate measure-ments include body mass and body size,glucocorticoid titers and blood cell countsas indicators of stress, and hematologicalmeasures that estimate hydration and reli-ance of cellular metabolism on stored bodyfat or protein. In Adelie penguins (Pygoscelisadeliae) reproduction is constrained by for-aging ecology, mode of transport, and thelatitude at which they live. Females that re-turn to the colony but do not breed are 10-12% lighter than females that do, but malenonbreeders are as heavy as male breed-ers and have similar hormone levels. Pen-guins must fast for many weeks during re-production. Nest failure often occurs whenone parent does not return to the colony,

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and the fasting parent must eventually leave.During normal-length fasts corticosteronelevels do not change, but when fasts arevery long and birds have lost >35% of theirbody mass, corticosterone and hematocritincrease and prolactin decreases. Duringfasting ketone levels gradually increasewhile uric acid levels are low, but in birdswith the longest fasts, ketone levels fall anduric acid levels increase, indicative of aswitch from using fat to body proteins for me-tabolism. These physiological and endo-crine measurement help to reveal the proxi-mate mechanisms at the individual level thatlink environmental and population-levelvariation in penguin reproductive success.

69.3 VOGEL, S. Duke University Muscle asengine: a biomechanical look at some an-cient tasks.

Using muscle to power large-scale taskspresents specific difficulties. For instance,the relatively uniform size of people and draftanimals imposes problems of scaling, andmuscle’s inability to produce rotary motionmeans that non-functional mass must be ac-celerated and decelerated. Thus (1) theblocks used for the Egyptian pyramids mayhave deliberately been made large in orderto minimize the surface area that had to becut and dressedóperhaps we should focusless on how they were moved than on howthe quarries could produce a well-cut stoneevery two minutes. The blocks were cer-tainly dwarfed by stones moved long dis-tances by less socially-elaborate cultures.(2) Oars and paddles do well for small boats,but if oar power is to scale with anythingclose to hull area, multiple manning of eachis necessary. As a result, the masses of theoars of the great triremes and galleys, oftenover 100 kg each, imposed excessive iner-tial loads. A good alternative, treadmill-pow-ered paddle-wheels, saw little use outsideChina. (3) Ballistae, using stretched tendonas energy store, minimized non-functionalmoving mass but were limited in both forceand power to what one or two artillerymencould generate. By contrast, medievaltrebuchets, using gravitational storage, couldemploy large numbers of operators, but theirmassive arms imposed low inertial efficien-

cies.

P1.72VOGT, D., Plattsburgh State Univer-sity, NY. Cold-hardiness in bumblebees.

Muscular thermogenesis enables indi-vidual bumblebees to fly while foraging inthe cold. However, this ability comes withgreat risk. Bumblebees are unable to warm-up and fly if they cool to near freezing airtemperature or if they have inadequate fuelreserves to sustain a high enough body tem-perature for flight. Bumblebees were sub-jected to prolonged exposure to cold air tem-peratures without a food source to determinesome of the limits in performance (activityand flight). No discernable differences wereobserved between drones and workers.Bees with ample food in the crop were ca-pable of enduring several days at cool airtemperatures. Larger body size may in-crease survival time at near-freezing air tem-perature. Prolonged exposure to near-freez-ing air temperature appears to suppress theability of bees that have been stimulated towarm-up at 22C when compared to beesacclimated to warmer air temperature.

S13.5VON BLUM, R., Evaluation Consult-ant. How to use evaluation to improve yourinstructional program.

Evaluation? “The systematic investiga-tion of the worth or merit of an object.” Howdo we go about evaluating the merit of ourinstructional programs? What are the tech-niques and procedures we can use to findout what’s really happening–before, during,and after we initiate education reform? Dur-ing this presentation, you will get an over-view of what it means to evaluate a wholeinstructional program, what it takes to con-vince our colleagues, administrators, fund-ing agencies, and ourselves that our effortsin science education reform are making adifference.

19.5 VONESH, J. R. *, DE LA CRUZ, O.,University of Florida, Gainesville. Modelingthe effect of UV-B induced egg-stage mor-tality on the population dynamics of the com-mon toad.

There has been increasing evidence ofwidespread population declines of amphib-ians from relatively undisturbed habitats. It

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has been suggested that ultraviolet radia-tion induced embryonic mortality has con-tributed to the decline of some species. How-ever, the connection between UV inducedmortality and population dynamics has notbeen examined explicitly. We examine thepopulation-level consequences of UV-B in-duced egg mortality in the Common toad,Bufo bufo using a stage-structured popula-tion model that includes terms for densitydependent juvenile recruitment, and juve-nile and adult survivorship. Our results sug-gest that, except for a small range of valuesfor some parameters, the stable adult popu-lation size shows little variation underchanges in the survival of the eggs. Thus,based on our model increased egg-stagemortality due to exposure to UV-B alone isunlikely to result in declining adult popula-tions for this species. The model exhibits simi-lar behavior under a wide range of param-eter values, which leads us to believe it tobe an adequate analysis tool. The sensitiv-ity analysis provides information on whichparameters strongly affect the stable adultpopulation size, and this could lead to otherhypothesis on the causes of the reduction ofamphibian populations.

S3.12WAINWRIGHT, P.C., University of Cali-fornia, Davis. The role of motor patterns inthe evolution of fish feeding performance.

How are fish feeding mechanisms modi-fied during evolution to produce diversity infeeding ability and feeding ecology? In par-ticular, are feeding motor patterns alwaysaltered in conjunction with biomechanicalchanges of muscle-skeleton linkages? Stud-ies of the evolution of fish feeding mecha-nisms have consistently yielded two verydifferent answers to the latter question. Theorigin of novel trophic habits can be associ-ated with considerable modification of themotor pattern that drives feeding behavior.This occurs when the new prey type is cap-tured or processed using a new behavior ormechanism. Examples include the origin ofmollusc crushing in several groups of teleo-sts, and the origin of algae scraping inparrotfishes. Alternatively, a number of in-dependent, quantitative interspecific com-parisons of the motor patterns used in preycapture by fishes have found that the aver-

age value of burst duration and onset timeof homologous muscles does not vary sig-nificantly across species. This is true evenin some cases where the jaw mechanics,feeding performance and patterns of preyuse of the species differ considerably. I sug-gest that this evolutionary conservation ofmotor patterns does not represent a con-straint on the malleability of the neuromus-cular system. There is abundant evidencethat motor patterns can readily be alteredand that they are under fine control by indi-vidual fish. Rather, conservation of a func-tional trait that is inherently quite flexible sug-gests that altering it is neither effective nornecessary for modifying feeding perfor-mance. Some trophic radiations may thusinvolve extensive morphological changeswith consequences for linkage mechanicsand prey capture kinematics, but with fewconcomitant changes to the motor patternsthat control feeding.

S6.7 WALKER, J.A., University of SouthernMaine. Swimming in air, flying under water:physical constraints on the design of oscil-lating wings, fins, legs, and feet at interme-diate reynolds numbers.

Why do some animals swim by rowingappendages back and forth while others flyby flapping them up and down? One an-swer lies in the sharply divergent physicalenvironments encountered by small, slowanimals, and large, fast animals. Flappingappendages allow large animals to movethrough a fluid environment quickly and effi-ciently. As size and speed decrease, how-ever, viscous drag dominates the force bal-ance. Consequently, the geometry of ap-pendage motion allows a rowing, but notflapping, appendage to exploit large skin-friction drag for thrust generation. I used botha comparative analysis and a mathematicalmodel to address the question “At what scaledoes a rowing appendage work more effi-ciently than a flapping appendage?” Thecomparative analysis suggests that flappingflight is less effective than rowing at Re lessthan 50 -100. A simple quasi-steady, blade-element model of virtual oscillating append-ages has several important results. First, themechanical efficiency of both rowing andflapping decrease dramatically with scale.

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Second, at Re 1, rowing appendages aremuch more efficient than flapping append-ages. At Re 10, flapping appendages aremore efficient than rowing appendages onlyif high reduced frequencies are allowed.Third, flapping appendages are much moreefficient than rowing appendages at com-monly found reduced frequencies when thescale increases to about Re 200. These re-sults suggest at what scale we might findaquatic animals flying under water or aerialanimals swimming in air.

52.1 WALLACE, B.D.*, HAMMER, H.S.,WATTS, S.A., LAWRENCE, J.M.,LAWRENCE, A.L., University of Alabama atBirmingham, University of Alabama at Bir-mingham, University of Alabama at Birming-ham, University of South Florida, Tampa,Texas A&M University, Port Aransas. The ef-fects of dietary protein concentration ongrowth of juveniles of the sea urchinLytechinus variegatus.

Juveniles (ca. 14 mm diameter, n=120)were collected at St. Joseph Bay, FL in March2000. They were held in 80 L aquaria withartificial seawater at 21 C and 32 ppt salinity.The juveniles were fed ad libitum one of fourisocaloric diets varying in protein concen-tration (14, 23, 32 or 50%) for 14 weeks. Testdiameters increased from 14 mm to 19.8,29.4, 30.5, or 32.6 mm in individuals fed the14, 23, 32, or 50 % protein diet, respectively.Total wet weights increased from 1.06 g to4.7, 13.7, 14.4, or 16.5 g in individuals fedthe 14, 23, 32, or 50 % protein diet, respec-tively. Specific growth rates were 1.7, 2.9,2.9, or 3.1 % body wet weight increase perday. At week 14, gonad indices (wet gonad/wet weight x 100) were 2.5, 7.4, 7.2 or 9.1 forthe 14, 23, 32, or 50 % protein diet, respec-tively. Apparent dry matter digestibility, mea-sured on week 5 and 10, ranged from 83 to90 % (lowest in those fed the low proteindiet) and did not change over time. Survivor-ship was 100% in individuals fed the 32 or50 % protein diet, but was reduced to 77 or70 % in those fed the 14 or 23 % protein diet.Low concentrations of dietary protein influ-enced growth rate, gonad production, andsurvivorship, but had minimal influence onabsorption efficiency. Gonad production oc-curred in individuals whose diameters were

smaller than reported previously in fieldpopulations. The requirement for a proteindiet of > 23 % corroborates with ecologicalstudies that indicate L. variegatus preferen-tially consumes epibionts and animal tissuesin preference to seagrasses. Funded by Mis-sissippi-Alabama Sea Grant.

S7.8 WALLACE, R.L., Ripon College. Roti-fers: exquisite metazoans.

Being among the first microorganismsseen by children exploring the world withtheir new microscope or high schoolers inbiology class, rotifers have fascinatedpeople for nearly 325 years, ever sinceLeeuwenhoek began describing them in hisletters to the Royal Society in London late inthe 17th century. And while these organ-isms have captivated the imagination ofmany, including writers of science fiction andartists working in glass, they are generallyignored by research biologists, for probablyfewer than 350 people world-wide study ro-tifers on a regular or even irregular basis.Accordingly, rotifer research is still an openfield where amateurs and professionalscoming lately to the discipline can make animmediate positive impact on our knowl-edge of these curious little beasties. Pos-sessing an anterior ciliated field (corona)used in locomotion and/or food gatheringand a pharynx (mastax) equipped with com-plex jaws (trophi), rotifers comprise a mod-erately-sized phylum (=1850 species) of tiny(=100-1,500 mm), bilaterally symmetrical,eutelic metazoans, traditionally grouped withthe pseudocoelomates. Rotifers are saccateto cylindrical animals with three prominentregions (corona, trunk, foot) and a body cav-ity in which are suspended the internal or-gans. Unfortunately these generalizationsgrossly oversimplify a rich and fascinatingdiversity. Chief among their charms for re-search is their ease of culture (includingchemostat technology) and the fact that thereis much that remains unknown about thephylum. Here I review the trends in rotiferresearch over the past 25 years, note thedirections of current work, and suggest ar-eas where future efforts may prove profit-able. These fields include, but certainly are

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not limited to, the following: ecology, molecu-lar biology, phylogeny, systematics, biophys-ics, neurophysiology, biology of aging, andcell and development biology.

P3.2 WALSH, E.J.*, DE LA RIVA, V., Univer-sity of Texas, El Paso. Molecular systematicsof the brachionidae (phylum rotifera) basedon internal transcribed spacers (its) of thenuclear ribosomal gene complex.

Rotifers play important roles in freshwa-ter communities. Despite their ubiquity, littleis known about their evolutionary relation-ships. From an ecological perspectivebrachionid rotifers have received consider-able attention yet the most basic feature oftheir phylogeny, the monophyly of the group,has not been investigated. We have se-quenced both ITS regions from representa-tives of 5 genera and 23 species withinBrachionidae in addition to species fromfamilies Epiphanidae, Lecanidae, andEuchlanidae. Both regions contained manyinformative sites and each data set containeda strong phylogenetic signal as indicated byg1 values of -0.0755 (p<0.01) and -0.6688(p<0.01) for ITS1 and ITS2, respectively. Datasets were analyzed individually and in com-bination using parsimony and maximum like-lihood. Support for monophyly of theBrachionidae was found in all analyses.Monophyly of genera Keratella andNotholca were also supported. The positionof Plationus patulus is investigated as is theplacement of genus Rhinoglena.

P2.83WALTER, R. *, OTTER-STROM, J.,CARRIER, D., University of Utah. Effects ofbody morphology on vertebrate rotationalinertia.

Because the force required to rotate abody about an axis is directly proportionalto its rotation inertia about the axis, it islikely that animals with high rotational in-ertia would be constrained in their turningabilities. Using the fact that a physicalpendulumís period is proportional to itsrotational inertia1/2, we measured the ro-tational inertia in two groups of vertebrateswith greatly different body shapes: murianrodents and lizards (Iguana iguana andVaranus exanthermaticus). A small lizardhas more than double the rotational iner-

tia about its center of mass as an equiva-lent size rodent. Because, in geometri-cally similar animals, rotational inertiascales with mass^5/3, while muscle forcescales with mass^2/3, larger animals areexpected to have more difficulty turning.Rotational inertia scaled nearly isometri-cally for the muiran rodents, and with slightnegative alometry for the varanids andiguanas. This suggests that either theseanimals are not constrained by rotationalinertia due to their relatively small size, orthat larger rodents and lizards are poorerturners than smaller ones. The basalsynapsids from which cynodonts andmammals are derived had a body mor-phology best represented by recent lizardssuch as varanids or iguanas. The loss ofthe large muscular tail and elongatedbody form during synapsid evolution re-duced rotational inertia and likely im-proved turning ability.

63.4 WALTERS, L.J.*, ABGRALL, M.J., Uni-versity of Central Florida, Orlando. Impact ofdrift species (Gracilaria compressa,Zoobotryon verticillatum) on the recruitmentand fitness of sessile invertebrates.

Mosquito Lagoon is the northern-mostestuary in the Indian River Lagoon system.Here, large, dislodged masses ofmacroalgae and the bryozoan Zoobotryonverticillatum can be found drifting in the wa-ter at varying times throughout the year.Capture of drift in nets ranged from 0-158 g/hr. Drift algae and masses of Zoobotryon fre-quently become entangled around sub-merged hard surfaces, and thus may signifi-cantly impact the settlement and fitness ofhard-bottom sessile invertebrates. We ex-amined the impact of the common redmacroalga Gracilaria compressa and thebryozoan Zoobotryon on the recruitment andsurvival of two dominant fouling organisms,the barnacle Balanus eburneus and thebryozoan Bugula neritina. Manipulative fieldexperiments were designed to separate outchemical versus abrasion effects of the driftorganisms. In recruitment trials, replicatesurfaces were submerged as one of fivetreatments: caged with live drift species,caged with drift mimic, empty cage, partialcage and uncaged control. Plates were

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monitored every two days and reductions inrecruitment were found with both live driftand mimics of both species. The impact ofdrift on survival of recruits in 6-week trialswas next tested using the same design.Gracilaria, Gracilaria mimics and Zoobotryonsignificantly reduced the survival of Bugula.Survival of Balanus was only significantlyreduced by live Gracilaria. Thus, whenpresent, drift organisms can significantly al-ter sessile invertebrate community compo-sition.

40.5 WALTZEK, T.B.*, WAINWRIGHT, P.C.,University of California, Davis. The functionalmorphology of jaw protrusion amongneotropical cichlids.

The evolution of protrusible upper jawsamong acanthopterygian teleosts has longbeen argued a major factor contributing tothe success of this extremely diverse groupof fishes. Yet, few studies have investigatedupper jaw protrusion in a comparative frame-work. Additionally, previously unstudied taxaare revealing new kinematic pathways ofprotrusion of not only the upper jaws but alsothe lower jaws. In this investigation the kine-matics, functional morphology, and perfor-mance measures of upper and lower jawprotrusion were analyzed among severalCentral and South American cichlids.Petenia splendida and a member of its sis-ter genus, Caquetaia spectabile, both whichexhibit extreme jaw protrusion were com-pared to each other and to the basaloutgroups Cichla ocellaris and Astronotusocellatus which do not exhibit the same levelof jaw protrusion. Digital high speed film(500 fps) of feeding on live guppy prey wasutilized to compare kinematic and perfor-mance variables. Dissection and bone/car-tilage clearing and staining were used tocompare the functional morphology amongthe taxa. Unlike much of the previous workon jaw protrusion, kinematic data was usedto measure prey capture performance bymeasuring the ram and suction componentsof successful feeding events. Feeding per-formance data was used to explore the rela-tionship between jaw protrusion and thegeneration of suction and ram. Compari-sons of dissected and cleared and stainedspecimens revealed novel joints within the

suspensorium allowing considerable lowerjaw protrusion coordinated with upper jawprotrusion in Petenia splendida andCaquetaia spectabile. Finally, patterns ofkinematic and morphological convergencewill be compared among Petenia splendida,Caquetaia spectabile, and other distantly re-lated extreme jaw protruding teleosts.

38.4 WARKENTIN, K.M., University of Ken-tucky and Smithsonian Tropical Re. Hatch-ing as a defense against egg predators: therole of vibrational cues.

Red-eyed treefrogs, Agalychniscallidryas, lay their eggs on vegetationoverhanging water, into which the tad-poles fall at hatching. The age and devel-opmental stage at which hatching occursvaries. The ability of hatchlings to escapefrom aquatic predators improves with de-velopment, and undisturbed embryoshatch relatively late. However, well beforespontaneous hatching occurs, embryoswill hatch rapidly in response to attack byegg-eating snakes or wasps. The rapid,synchronous early hatching (escapehatching) appears to be a specific re-sponse to mechanical disturbance of theegg clutch by predators. It occurs only af-ter predators have begun physically ma-nipulating eggs, and similar responsescan be induced with artificial mechanicalstimuli. Embryos are, however, unrespon-sive to a variety of benign natural distur-bances, including wind, rain and earth-quakes, as well as to some artificial distur-bances. I used a sub-miniature acceler-ometer inserted among the embryos in A.callidryas egg clutches to record vibrationsproduced in snake attacks, wasp attacks,rain, and several types of artificial distur-bance. I presented these recorded vibra-tions to hatchable eggs via a minishakerinterfaced with the clutches through a setof tines inserted between eggs. Playbacksof recorded snake attacks elicited morehatching than did playbacks of intensity-matched rain recordings. Furthermore,playbacks of natural rain elicited lesshatching than did playbacks of rain thatwere edited to clump drops together andartificially extend still intervals betweenperiods of vibration. Embryos may use

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simple temporal patterns of vibration to dis-tinguish among benign and dangeroussources of physical disturbance.

48.5 WARNER, D.A.*, ANDREWS, R.M.,Virginia Tech, Blacksburg. Maternal and en-vironmental contributions to hatchling phe-notypes and survival of the lizard Sceloporusundulatus.

Phenotypic variation of hatchling reptilesis influenced by environmental conditionsduring egg incubation and by various ma-ternal sources. We investigated the effectsof incubation moisture conditions, maternalyolk investment, and clutch on various phe-notypic traits and subsequent survival ofhatchlings of the lizard, Sceloporusundulatus. Eggs from 28 clutches were in-cubated under two moisture regimes (-150kPa and -530 kPa) to evaluate the effect ofincubation moisture on hatchling pheno-types. Yolk was removed from eggs in an-other treatment to evaluate the effect of yolkinvestment on hatchling phenotypes. Afterhatching, snout-vent length, mass, taillength, growth rate, thermal preference, run-ning speed, and desiccation rate were mea-sured for each hatchling. Hatchlings werereleased at a field site near Blacksburg, Vir-ginia and monitored until winter and againthe following spring. Incubation moisturehad a small effect on hatchling body size;hatchlings incubated under wet conditionswere slightly larger than those from dry con-ditions. Maternal yolk investment had a simi-lar effect on hatchling body size; eggs withyolk removed resulted in small bodiedhatchlings. Neither incubation moisture noryolk investment had an effect on perfor-mance; clutch explained most of the varia-tion in phenotypes. Similarly, survival wasnot affected by treatment, but was associ-ated with clutch. Hatchlings that survivedlonger than 6 weeks grew more slowly thanthose that did not survive to six weeks. As-suming rapid growth rate is associated withhigh activity, the more rapidly growinghatchlings could have been conspicuous topredators. In general, our observations dem-onstrate the importance of maternal (clutch)contributions to offspring fitness.

S14.9WASSERSUG, R.J., Dalhousie Uni-

versity. Problems in metamorphosis abovethe molecular level.

Tadpoles from a single clutch, whichhatch at approximately equal size, can varyin size by nearly an order of magnitude bythe time they metamorphose. This observa-tion has led to extensive research by ecolo-gists on social and environmental factors thatinfluence metamorphosis. Independently,molecular biologists have made great stridesin understanding genetic programs in tad-pole tissues that are activated when meta-morphosis begins. What has been largelymissing in our efforts to understand meta-morphosis are the mechanistic links be-tween the factors studied by ecologists andthe genes studied by molecular biologists.We do not understand, for example, howextrinsic factors, such as density or waterdepth, are sensed by amphibian larvae andultimately manifested as changes in genetranscription within specific tissues. In my talkI will review some of the environmental fac-tors that influence size at metamorphosis byinfluencing growth. I will then present a setof heuristic models that explore the balancebetween growth and metamorphosis at thetissue level, in an effort to develop testablehypotheses about the link between the en-vironmental and molecular regulation ofmetamorphosis.

59.3 WATTS, P.*, FISH, F., Applied FluidsEngineering, Inc., West Chester University.Fluid dynamic role of tubercles on hump-back whale flippers.

Tubercles are leading edge protrusionson the flippers of humpback whales(Megaptera novaeangliae). Humpbackwhales are the only baleen whales that cap-ture prey through routine tight maneuvers.We investigated the fluid dynamic benefitsof tubercles with regard to force productionby the flippers. Fluid dynamic simulationswere carried out with inviscid, panel method,computer simulations applied to steady,three-dimensional flow about an airfoil. At amodest angle of attack of 10 degrees, thetubercles enhance lift by 5% and reduce dragby 10%, respectively. The additional lift isderived in part from low pressure regionsbetween tubercles. Drag is reduced through

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several mechanisms, although the dominantone is lowered induced drag due to com-partmentalization of the low pressure regionsover the airfoil. The result is an increase inboth the relative and absolute performanceof humpback whale flippers as control de-vices during tight maneuvers. In modifyingthe flow over the flipper, the tubercles canalso extend the useful performance enve-lope of the flipper. This work provides thefirst dynamical evidence that tubercles couldindeed be functional adaptations that en-hance prey capture for humpback whales.

S11.2WEBB, P.W., University of Michigan,Ann Arbor, MI. Mechanisms for the control ofposture and swimming trajectories of fishes.

Fish with a high density ratio can achievestability on the substratum. Morphologicaldesign criteria stabilizing station holding andmaximizing current speeds displacing fishare well known, but optimal designs for allcriteria are not possible. In the water col-umn, fish are inherently unstable. Posture offish in the water column is not stable be-cause the metacentric height is typicallynegative and the centers of mass are sepa-rated longitudinally. When gas inclusions areused to regulate density, altitude is not stable.Neutrally buoyant fish are unstable in coast-ing. Biological materials are deformable, andsome control surfaces are forward of thecenter of mass both of which tend to amplifydisturbances. When swimming, stability de-pends on dynamic controls, generated bythe same range of body and fin appendagesthat introduce instabilities for maneuvering.Dynamic forces may be passive, resultingfrom flow over the control surface due to themotion of the body, or self-powered. Pow-ered controls are required to stabilize alti-tude and swimming trajectories at lowspeeds, but these are energetically expen-sive. Passive controls are effective and moreeconomical at higher speeds and can beself-correcting. Predictable disturbances,such as recoil, may be damped using pas-sive systems, but powered control is requiredto improve the smoothness of swimming tra-jectories. Unpredictable disturbances are agreater challenge, especially when self-cor-rection is not possible or inadequate, and

when response delays occur. Some prelimi-nary observations suggest reliance on pow-ered control affects the distribution of vari-ous fish morphs in hydrodynamically vari-able habitats.

P2.56WEBSTER, M.D.*, CHAPLIN, S.B., St.John’s University, University of St. Thomas.Student initiated projects in animal physiol-ogy lab instruction.

To enhance student learning of physiologi-cal concepts, build a departmental cultureof inquiry, and motivate students to pursuestudies of animal biology, we use indepen-dent laboratory projects as a primary modefor instruction in our comparative animalphysiology courses. Students are first ex-posed to standard recording techniques andanimal preparations. After directed litera-ture studies and discussion of experimentaldesign, we ask students to design their ownlaboratory investigations. Four to six weeksof lab meetings are devoted to the students’independent work. End-of-term reports takethe form of research articles or poster pre-sentations. Focused studies that are exten-sions of the published literature or that usewell studied organisms or methods seem tobe most successful; we direct students awayfrom equipment-intensive or overly broadprojects. Our experience has been that thismodel of laboratory instruction takes moreinstructor time for animal husbandry, equip-ment maintenance, and ordering suppliesthan courses using traditional “cookbook”exercises. We also observe, however,greater student interest and enthusiasm, andhigher academic achievement in success-ful students. Students take ownership of thematerial, become experts on a particulartopic, and understand concepts at a depthnot realized in most undergraduate sciencecourses.

S11.5WEIHS, D., Technion-Israel Inst.ofTechnology. Stability versus maneuverabil-ity in aquatic locomotion.

The dictionary definition of stability as“Firmly established, not easily to be changed”immediately indicates the conflict betweenstability and maneuverability in aquatic lo-comotion. The present paper addresses sev-

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eral issues resulting from these opposingrequirements. Classical stability theory forbodies moving in fluids is based on devel-opments in submarine and airship motions.These have lateral symmetry, in commonwith most animals. This enables the separa-tion of the equations of motion into two setsof 3 each. The longitudinal set, which includesmotions in the axial (surge), normal (heave)and pitching directions, can thus be sepa-rated from yaw, roll and sideslip motions. Thishas been found useful for longitudinal sta-bility studies based on coasting configura-tions (e.g. Weihs, 1993) but is not applicableto the analysis of turning, fast starts and vig-orous swimming, where the lateral symme-try of the fish body is broken by bendingmotions. The present paper will examinethe stability vs. maneuverability aspects ofthese asymmetric motions, starting off withan analysis of the conditions under whichthe separation of equations of motions is le-gitimate, and a definition of the equations tobe used in cases where the separation isnot accurate enough. Several examples arepresented, including: 1) BCF locomotion isinherently unstable in yaw due to the side-ways excursions of the rear body and theflexibility of the body. a) in rectilinear swim-ming, the pectorals are used to counteractand damp yawing motions of the head. b)turning motions, in which the instability isutilized, to improve performance. c) rapidstarting, where various combinations of aand b are applied. 2) An analysis of the influ-ence of the highly elliptic shape of bodycross-sections in certain species in enhanc-ing stability by reducing the interaction ofyawing and rolling motions.

35.6 WEINSTEIN, R.B.*, HARTMAN, J.H.,University of Arizona, Tucson. Modeling theintermittent exercise strategy of “ride and tie”competition.

Intermittent exercise is characterized bybouts of exercise alternated with pauses.When exercise bouts are performed at a highintensity, brief pauses provide time for re-covery from the preceding exercise bout. In“Ride and Tie”, a competitive sport incorpo-rating intermittent exercise, teams consist oftwo humans, who alternate running and

riding, and one horse, who alternates run-ning and resting. Teams may make 30-40exchanges (i.e., ties) in a 60 km race. Wemodeled an infinite race as a series of exer-cise and recovery intervals. Human and Ara-bian horse records were used to derivemaximum running speed as a function ofinterval distance. Interval training tableswere used to derive minimum recovery timeas a function of exercise intensity and dura-tion. For each interval distance from 0.4-5.0km we determine the conditions (i.e., run-ning speed, percent effort, and recovery time)under which the humans or the horse arethe limiting factor(s), select the conditionsthat maximize team speed, and then selectthe interval distance that maximizes teamspeed. The final solution provides the inter-val distance and running time for each teammember that maximizes team speed. A teamcomposed of a world class horse and hu-mans should run 3.2 km intervals. Slowerteams should use shorter intervals. Increas-ing the minimum recovery time slows maxi-mum team speed and decreases the opti-mal interval distance. Several features of the“Ride and Tie” model, such as the trade-offbetween exercise intensity and recoverytime, are applicable to modeling traditionalforms of intermittent exercise.

30.2 WELCH, A.M., University of NorthCarolina, Chapel Hill. What is good about“good genes” in gray tree frogs: how is callduration linked with larval quality?

Male displays traits are predictive of off-spring quality in some species, althoughthe basis of the relationship between dis-play traits and offspring quality is not wellunderstood. Female gray tree frogs prefermale calls of long duration, and offspringof males with long calls were of higherquality than were offspring of males withshort calls in laboratory experiments. Itested whether variation in tadpole activ-ity and metabolism contributed to an ef-fect of call duration on larval period or massat metamorphosis. I measured time spentfeeding, ingestion rate, digestive efficiency,larval period, and mass at metamorpho-sis for tadpoles from eight maternal half-sibships (each sired by one long-calling

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male and one short-calling male) whichwere raised individually in the lab, at twofood levels. In the low food treatment, off-spring of long-calling males were largerat metamorphosis than were offspring ofshort-calling males, but had similar larvalperiods; in the high food treatment, off-spring of long- and short-calling males didnot differ in mass at metamorphosis or lar-val period. At both food levels, tadpolesthat spent more time feeding tended tohave higher ingestion rates, and tadpoleswith higher ingestion rates tended to haveshorter larval periods. In the low food treat-ment, higher digestive efficiency also con-tributed to shorter larval periods. Timespent feeding, ingestion rate, and diges-tive efficiency did not affect mass at meta-morphosis in either food treatment. Thus,the effect of call duration on mass at meta-morphosis detected in this experiment isnot attributable to variation in activity, in-gestion rate, or digestive efficiency. None-theless, variation in ingestion rate mayhave contributed to an effect of fatherís callduration on larval period in previous ex-periments.

P2.3 WELCH, J.M.* *, WAL-TERS, L.J.,YOUNG, C.M., Wittenberg University, Spring-field OH, University of Central Florida, Or-lando, Harbor Branch Oceanographic Insti-tution, Ft. Pierc. Effects of flow on larval re-lease behavior of the bryozoan Bugulaneritina.

The ubiquitous arborescent bryozoanBugula neritina lives attached to substrataand is subjected to tidal currents in estua-rine areas. Itslarvae have a very short plank-tonic period (minutes to hours), so the tim-ing of release relative to the state of the tideis critical in determining how far the larvaewill be transported during their planktonicexistence. Prior work has found that B. neritinarelease larvae upon exposure to bright lightsafter a period of darkness, akin to sunrise inthe field. However, no prior research hasconsidered whether B. neritina alters its be-havior in flow to release larvae during a par-ticular state of the tide. We compared thelarval release behavior of B. neritina in stillwater and in 1 and 5 cm s-1 flows in a flow

tank. There was no difference between re-lease in 1 cm s-1 flow and still water. How-ever, in 5 cm -1 flow, B. neritina released fewerlarvae than in still water. This indicates thatB. neritina preferentially releases larvae instill water or very slow flow, suggesting aselective pressure to retain larvae close totheir parent population, presumably to re-main in a favorable habitat.

S10.18 WELLEMS, T.E., EVANS, A.G.; Na-tional Institute of Allergy and InfectiousDiseases, National Institutes of Health.Coevolutionary genetics of Plasmodiummalaria parasites and their human hosts

Malaria has been invoked perhapsmore than any other infectious disease asa force in the selection of human geneticpolymorphisms. Evidence for genomeshaping interactions can be found in thegeographic and ethnic distributions of thehemoglobins, blood group antigens,thalassemias, host cell membrane mol-ecules, HLA classes and cytokines. Hu-man genetic variations and immuno-pro-tective defenses correspondingly influ-ence the structure and polymorphisms ofPlasmodium parasite populations, notablyin genes that affect the success and viru-lence of infection. Coevolutionary adapta-tions likewise occur with the mosquitoesresponsible for the transmission of malariaparasites in human populations. Four Plas-modium species are responsible for theusual human malarias. The species re-sponsible for the most acute and deadlyform of malaria, P. falciparum, is related toa avian parasite and may be a recent in-troduction into humans. The three otherparasite species have emerged fromlongstanding evolutionary relationshipswith primates, which may explain their ten-dency to produce less severe forms of thedisease. In Africa, where the selective forcefrom P. falciparum is strongest, the sever-ity of malaria and its manifestations varyin prevalence among human populations.Understanding the malaria-protective fac-tors and susceptibility determinants inthese populations should provide insights

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into pathogenesis and perhaps provide afoundation for advances against the dis-ease.

62.1 WENDT, D.E., University of NorthCarolina, Greensboro. Energetics of larvalswimming and metamorphosis in four spe-cies of Bugula (Bryozoa).

The amount of energy available to lar-vae during swimming, location of a suitablerecruitment site, and metamorphosis influ-ences the length of time larvae can spend inthe plankton. Energetic parameters such asoxygen consumption during swimming andmetamorphosis, and elemental carbon andnitrogen content were measured for larvaeof four species of bryozoans, Bugula neritina,B. simplex, B. stolonifera, and B. turrita. Thelarvae of these species are aplanktotrophicwith a short free-swimming phase rangingfrom less than one hour to a maximum ofabout 36 hours. There exists approximatelya 5-fold difference in larval volume amongthe four species, which scales linearly withelemental carbon content and, presumably,with the amount of endogenous reservesavailable for swimming and metamorpho-sis. Specific metabolic rate and larval sizewere inversely related. For larvae of a givenspecies, respiration rates remained similarfor swimming and metamorphosis; however,because the duration of metamorphosis isabout twice as long as a maximal larval swim-ming phase, it was more energetically de-manding. Larger larvae expended moreenergy to complete metamorphosis than didsmaller larvae, but in terms of the percent-age of larval energy reserves consumed,swimming and metamorphosis were more'expensive' for smaller larvae. A compari-son of the energy expended during larvalswimming calculated on the basis of oxy-gen consumption and on the basis of el-emental carbon decrease suggests that lar-vae of Bugula spp. may not use significantamounts of dissolved organic material (DOM)to supplement their endogenous energy re-serves.

S10.9 WERREN, J.H.; University of Roch-ester. Evolution and consequences ofWolbachia symbioses in invertebrates.

Wolbachia are a widespread group of

bacteria that commonly found in insects,isopods, arachnids and nematodes. Thesecytoplasmically inherited bacteria causea number of alterations in host reproduc-tion, including induction of sperm-egg in-compatibility, parthenogenesis, feminiza-tion of genetic males, and male-killing.These alterations enhance transmissionof the bacteria within host populations.Wolbachia may also have evolved mutu-alistic interactions with hosts. These bac-teria are capable of moving between dis-tantly related host taxa by mechanisms thatare as yet unclear. It has been proposedthat these bacteria may play a role in rapidspeciation in invertebrates; however, thisview is controversial. Information is pre-sented on the evolutionary biology of thesefascinating bacteria. In addition, theoreti-cal and empirical studies relating to thepossible role or Wolbachia in host specia-tion is discussed.

1.5 WESP, H.M.*, GIBB, A.C., NorthernArizona University. Escape response perfor-mance in the larval razorback sucker,Xyrauchen texanus.

The razorback sucker, Xyrauchentexanus, is an endangered fish native to theColorado River system. Previous researchsuggests that declines in wild populationsare due to a lack of larval recruitment. In thisstudy, we tested the hypothesis that poorescape response performance of larval ra-zorback suckers contributes to low recruit-ment. The larval escape response behav-iors of razorback suckers reared at 12* Cand 18* C were elicited and digitally re-corded over a developmental period to de-termine 1) if the larvae displayed the escaperesponse and 2) if maximum swimmingspeed during the response was significantlyslower than speeds reported for other fishlarva. Response behaviors for 56 razorbacksuckers were digitized using Didge analy-sis software. Larval razorback suckers diddisplay escape response behaviors, withspeed of the response increasing as lengthincreased during development. In addition,escape response speeds for suckers weresimilar to those reported for other fish larvaat the same size. Preliminary temperaturecomparisons indicate that maximum swim-

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ming speed during the escape shows a Q10

relationship of approximately 0.2. This lowvalue suggests that the colder water tem-perature does not significantly affect escaperesponse behavior. Thus, it appears that ra-zorback suckers are capable of acclimatingto lower Colorado River temperatures andpoor escape response performance doesnot contribute to the lack of recruitment inthe wild. Future work will compare escaperesponse performance between the nativerazorback sucker and an introduced spe-cies, the rainbow trout, Oncorhynchusmykiss.

3.4 WESTNEAT, M.W.*, Field Museum ofNatural History. Mechanical design for swim-ming in big fish: locomotor function in tunasand relatives.

The axial morphology of big marinefishes is a mechanical system specializedfor both high performance swimming andlong-distance cruising. The axial muscu-lature, connective tissues, and skeleton oftunas, mackerels, billfishes and their rela-tives exhibit modifications of the basicactinopterygian design for swimming thatreveal mechanisms for the generation andtransmission of force from muscle to cau-dal fin. The main horizontal septum isformed by the convergence of myoseptaand is the major transmitter of muscle forceto the axial skeleton. The vertical septumis formed from the serial neural and he-mal spines and a fabric of collagen fibersconnecting them. Using polarized light,the collagen fiber matrix of the vertical sep-tum is shown to be a crossed-fiber array inwhich fibers are oriented in two primarydirections, one coursing anterodistally andthe other posterodistally from the back-bone at angles ranging from 45-55ƒ to thevertebral axis. A biomechanical model isproposed for the function of the neuralspines and vertical septum inenergy stor-age and return in scombrids. In the tail, aposterior system of muscles and tendonsoperates the caudal fin of tunas, billfishes,and other taxa. Comparative morphologyof the hypochordal longitudinalis, flexordorsalis, flexor ventralis, infra-carinalis,supracarinalis, and interradialis muscles

is presented. A new mechanical model isproposed for the function of the caudalmuscles in fine tuning the shape and mo-tion of the caudal fin. Biomechanical mod-els make predictions about muscle func-tion and force transfer in locomotion of bigmarine fishes that may direct future re-search on muscle function. Key featuresof the locomotor design of tunas, macker-els and outgroups are highlighted on aphylogeny to identify the major evolution-ary stages in the functional morphology ofscombrid locomotion. ONR N000149910184and NSF DEB- 9815614.

68.5 WHEATLY, M.G.*, WOOD, T.J., RENICK,P., VERNOOY, J., TASCHENBERGER, L.,WENDELN, M., Wright State University, Day-ton, OH. Applying what you learned in class:transforming biological laboratory educationso that it is universally accessible.

Creating Laboratory Access for ScienceStudents (The CLASS Project) is an NSF-funded initiative to train educators to developlab exercises and field trips that are univer-sally accessible through attendance at a 2week workshop. Pre/post assessment hasdemonstrated that the CLASS workshopimproves educators’ attitudes about and pre-paredness to teach science to student withdisabilities. This talk will highlight how edu-cators have translated their CLASSroom ex-perience back to their home institution. Sys-temically reforming the biological laboratoryeducation of all students will involve build-ing a network of educators trained in sci-ence and disability. CLASS projectdisseminable products and web resourcescan assist in this endeavor. NSF grant DUE/CCD 9653121. http://biology.wright.edu/labgrant/index.html.

P1.30WHEATLY, M.G.*, ZHANG, Z., STINER,L.T.M., Wright State University, Dayton, OH.Characterization and localization of crayfishca pump and exchanger.

The crayfish molting cycle is used tostudy gene expression for membrane Catranslocating proteins specifically PlasmaMembrane Ca ATPase (PMCA) and Na/Caexchanger (NCX). Amino acid sequencesdeduced from cDNA sequences were used

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to design oligo-peptide antigens (15 mersfrom hydrophilic loop regions). Peptides wereconjugated to cationized BSA and used togenerate poly-clonal antibodies in rabbits.Antiserum against PMCA has been shownto bind to a single strong band at 150-160kDa in Western analysis of crayfish anten-nal gland; a weaker signal is detected in cray-fish hepatopancreas. No signal is detectedwith preimmune serum. Antiserum againstNCX binds with a strong band at 124 kDa incrayfish cardiac muscle. Immunohistochem-istry reveals hybridization of antiserumagainst PMCA to basolateral membranes ofantennal gland. Antiserum against NCXshows specific binding in heart muscle, axialabdominal muscle, antennal gland andhepatopancreas. Westerns are being usedto quantify relative expression during differ-ent stages of the molting cycle. (NSF grantIBN 9603723).

32.1 WHIDDEN, H.P.*, WOODS, C.A.,Augustana College, Rock Island, IL, FloridaMuseum of Natural History, Gainesville. As-sessment of sexual dimorphism in theantillean insectivoran Nesophontes.

The Antillean insectivoran Nesophontesis known only from subfossil material fromCuba, Hispaniola, Puerto Rico, and the Cay-man Islands. When the first Nesophontesspecies was described from Puerto Rico,specimens appeared to fall into 2 sizeclasses, and this size variation was inter-preted as sexual dimorphism. Additionalspecies discovered subsequently from otherislands also appeared to exhibit dimorphism,though these new species were smaller andthe dimorphism was less pronounced.Sexual dimorphism is minimal in extantinsectivorans, and the level inferred forNesophontes is unexpected. We used skullmeasurements taken on more than 1500Nesophontes specimens to evaluate thisproposed sexual dimorphism, as well as 3alternative hypotheses for the dimorphism:temporal variation, geographic variation, andpresence of additional unrecognized spe-cies. Study taxa were N. edithae from PuertoRico and N. paramicrus, N. hypomicrus, andN. zamicrus from Hispaniola. Temporal varia-tion and geographic variation are not sup-

ported by our data, and it is unlikely thatthere would be a cryptic species paired witheach of these recognized species. We there-fore conclude that Nesophontes did exhibitsexual dimorphism. The level of sexual di-morphism in these 4 taxa increasesallometrically, with the largest species (N.edithae) exhibiting much greater dimorphismthan the smallest species (N. zamicrus).

S10.7WHITE, B.A., University of Illinois, Ur-bana. Comparative microbial diversity in thegastrointestinal tracts of food animal spe-cies.

Molecular tools based on small subunit(SSU) rDNA gene sequences offer a pow-erful and rapid tool for the analysis of com-plex microbial communities found in the gas-trointestinal (GI) tracts of food animal spe-cies. Extensive comparative sequenceanalysis of SSU rRNA molecules represent-ing a wide diversity of organisms shows thatdifferent regions of the molecule vary in se-quence conservation. Oligonucleotidescomplementing regions of universally con-versed 16S rRNA sequence are used asuniversal probes while those complement-ing more variable regions of sequence areuseful as selective probes targeting species,genus, or phylogenetic groups. Different ap-proaches derive different information andthis is highly dependent on the type of targetnucleic acid employed and the conceptualand technical basis used for nucleic acidprobe design. Generally these approachescan be divided into DNA-based methodsemploying empirically characterized probesand rRNA-based methods based on com-parative sequence analysis for design andinterpretation of “rational” probes. Poly-merase chain reaction (PCR) based tech-niques can also be applied to the analysisof microbial communities in GI tracts. Directcloning of SSU rDNA genes amplified fromthese complex communities can be used todetermine the extent of diversity in these GIcommunities. Denaturing gradient gel elec-trophoresis (DGGE) is another powerful toolfor profiling microbial diversity of microbialcommunities in GI tracts. Sequence analy-sis of the excised DGGE amplicons can thenbe used to presumptively identify predomi-nant bacterial species. Examples of how

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these molecular approaches are being usedto study the microbial diversity of communi-ties from steers fed different diets, swine fedprobiotics, and Atlantic salmon fed aquacul-ture diets will be presented.

60.6 WHITE, T.D.*, REILLY, S.M., BuffaloState College, Ohio University. Abdominalmotor dynamics in mammal locomotion II:integration of ventilation with “cross-coupled”body support and footfall patterns in trottingopossums.

T.D. White and S.M. Reilly Buffalo StateCollege and Ohio University Abdominalmotor dynamics in mammal locomotion II:Integration of ventilation with “cross-couplet”body support And footfall patterns in trottingopossums. Video-flouroscopy and elec-tromyography were used to investigateepipubic bone movement and associatedabdominal muscle activation during loco-motion on a motorized treadmill in twodidelphid marsupials, Didelphis virginianaand Monodelphis domestica. In both spe-cies, the epipubic bones exhibited little move-ment during locomotion (only symmetricalgaits were observed) or ventilation. Ventila-tion was inferred through the visualizationof diaphragmatic displacements. The ob-served patterns of muscle activation of ab-dominal muscles (external oblique, internaloblique, rectus abdominus, pyramidalis)exhibited either four bursts of activity duringa stride (usually single-footed, slow walks)or two bursts per stride (faster, trotting gaits).In the former pattern, muscle activation wasbilateral. At higher velocities of locomotion,both bilateral and asymmetrical, unilateralactivation of muscles were observed.

P3.53WIBBELS, T.*, MURDOCK, C., Univer-sity of Alabama at Birmingham. Interclutchvariability of sex ratios produced at pivotaltemperature in a turtle with temperature-de-pendent sex determination.

The red-eared slider turtle, Trachemyscripta, has a Male/Female (MF) pattern oftemperature-dependent sex determinationin which cooler incubation temperatures pro-duce males and warmer temperatures pro-duce females. The pivotal temperature (tem-perature producing a 1:1 sex ratio) has beensuggested to be near 29.4oC. In the current

study, 20 clutches of eggs were incubated at29.4oC. All of the clutches were laid duringthe same 24 hour period and average clutchsize was approximately 8 eggs. Individualclutches were kept separate throughout in-cubation and were rotated within incubators.Of the 20 clutches, 19 produced viablehatchlings. The sex of hatchlings was as-sessed by examining the structure of thegonads. Overall, an approximate 1:1 sexratio was produced (79 males:78 females).However, the results reveal significantinterclutch variation in sex ratios. Clutch sexratios varied from 100% male to 100% fe-male. The results support the hypothesisthat pivotal temperatures may vary due toclutch-specific factors.

P3.18WIGGINS, R.C.*, Mc-CLELLAND, S.,West Virginia University School of Medicine,West Virginia Geological and EconomicSurvey. Trackway of a Pennsylvanian tetra-pod (amphibian?).

The trackway of a tetrapod, worm tracks,fern imprints, and other surface featuresfossalized in a soft mud from the Pennsyl-vanian period have been recovered froma West Virginia coal strip-mine. Stride andpace analysis over a recovered distanceof about 150 cm indicate that the tetrapodfeatured four gracile digits on the presump-tive forelimb and five on the hind limb, withstocky body proportions. The stride lengthbetween each imprint of the same limb isessentially constant at 29 cm, apparentlyin a slow walk. There is no over-stride ofone limb’s imprints upon the other, indi-cating the the trunk length is neither rela-tively long with short limbs, nor short withlong limbs. The palmar (3.5 cm diameter)and plantar (4.0 cm diameter) imprints areseparated from left to right by a pace widthof about 14 cm (center to center). The paceangulation from righ to left, etc measured95-97 degrees, which falls in the range ofliving salamanders and reptiles, and indi-cates the limbs were relatively well posi-tioned under the weight of the body. Theabsence of a tail imprint indicates it waseither missing, too short to drag in the mud,or held errect. The palmar and plantar im-prints are smooth, i.e. without scales, un-der magnification which shows fine detail

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in other surface features of the trackway.The trackway has been interpreted as evi-dence of an amphibian in the Pennsylva-nian period.

S3.3 WILGA, C.D.*, HUETER, R.E., WAIN-WRIGHT, P.C., MOTTA, P.J., University ofRhode Island, Kingston, Mote Marine Labo-ratory, Sarasota, FL, University of California,Davis, University of South Florida, Tampa.Function and evolution of upper jaw protru-sion mechanisms in elasmobranchs.

Upper jaw protrusion is an importantcomponent of the feeding mechanism inmost elasmobranchs. To quantify the me-chanics of feeding, particularly those of up-per jaw protrusion, in four diverse species ofelasmobranchs we used anatomical dissec-tion, electromyography and high-speedvideo recordings. Our results show that whilecertain muscles show a common pattern ofmotor activity among the four species dur-ing feeding, other muscles are functionallyand evolutionarily plastic. Our observationsof elasmobranch upper jaw protrusionmechanisms suggests a mosaic of charac-ter changes over the course of evolution thatinvolve anatomical changes in all cases andmodifications of muscle activation patternsin some cases. The muscles involved in up-per jaw retraction also show modulation insome species and may be active during jawopening as well as in jaw retraction. The pri-mary jaw closing muscle in a durophagousshark exhibits an extended double-burst pat-tern of motor activity during crushing of hard-shelled prey. Within the evolution of feedingmechanisms of elasmobranchs, there areseveral structural changes that retain a con-served motor pattern and behavior. At leastone instance of structural modification is ac-companied by an alteration in the motor pat-tern which led to a change in behavior. Fi-nally, several instances of plasticity in acti-vation of certain muscles exist.

3.6 WILGA, C.D.*, LAUDER, G.V., Univer-sity of Rhode Island, Kingston, Harvard Uni-versity, Cambridge, MA. Function of the het-erocercal tail in sharks: quantitative wakedynamics during steady horizontal swim-ming and vertical maneuvering.

The function of the heterocercal tail in

sharks has long been debated in the litera-ture. Previous kinematic data have sup-ported the classical theory which proposesthat the beating of the heterocercal caudalfin during steady horizontal locomotionpushes posteroventrally on the water whichgenerates a reactive force directedanterodorsally. To quantify the function of theheterocercal shark tail during both horizon-tal locomotion and vertical maneuvering, wemeasured the orientation of tail vortices shedinto the wake and the orientation of the cen-tral vortex jet through the core of these vorti-ces. We used digital particle imagevelocimetry (DPIV) with both horizontal andvertical light sheet orientations to quantifypatterns of wake velocity and vorticity be-hind the heterocercal tail of both leopard andbamboo sharks swimming freely at 1.0 L/s.Analysis of flow geometry indicates that bothleopard and bamboo shark tails generatestrongly tilted vortex rings with a mean jetangle of approximately 40ƒ below horizon-tal during steady horizontal swimming. Thecorresponding angle of the reaction force ismuch greater than either body angle (mean~11o) and the angle of the path of motion ofthe center of mass (mean ~0o), thus stronglysupporting the classical model for steady hori-zontal locomotion. Vortex jet orientation issignificantly more inclined than the relativelyhorizontal jet generated by sturgeon tail vor-tex rings, further supporting the substantialdifferences in function in the heterocercaltails of sharks and sturgeon.

55.1 WILKENS, J.L., YAZAWA, T.,SHINOZAKI, T., ter KEURS, H.E.D.J., Univer-sity of Calgary, Calgary, Tokyo MetropolitanUniversity, Tokyo, Tohoku University, Sendai,University of Calgary. Sites and mode of ac-tion of proctolin and F2 on lobster cardiacmuscle.

At low concentration (10-10 M), the pep-tide hormones proctolin (PR) and F2 causean increase in the amplitude of electricallyevoked contractions of lobster heart ostialvalve muscle. At higher concentrations (PR>10-9 M, F2 >10-7 M), each peptide also in-duces contracture. The increases in contrac-ture and contraction force are proportionalto increases in [Ca2+]i. The prolonged eleva-tion of [Ca2+]i during PR-induced contracture

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causes a right shift in the force-pCa curveindicating a decrease in myofibrillar sensi-tivity to Ca2+. Reducing [Ca2+]o or blockingCa2+ channels with Cd2+ or nifedipine re-duced contractile force and PR responses.Blocking sarcoplasmic reticular Ca2+ releasewith ryanodine reduced phasic contractionsbut did not prevent PR-induced contracture.A number of inhibitors of protein kinase Aand C did not alter PR or F2 effects. We con-clude that PR and F2 bind to sarcolemmalreceptors to increase Ca2+ currents. Neitherpeptide appears to act via intracellular sig-nal transduction pathways.

60.2 WILLEY, J.S.*, REILLY, S.M.,BIKNEVICIUS, A.R., Ohio University, Athens.The mechanics of a semi-erect posture: lo-comotor force studies in Alligator.

Most studies of locomotor mechanicshave focused on species utilizing erect pos-tures. In order to begin to understand themechanics of non-erect postures, we quan-tify the single limb locomotor function andwhole body mechanics of Alligatormississippiensis using force platform arrays.Whole body mechanics are used to evalu-ate phase relationships of potential and to-tal kinetic energies used by Alligator duringhigh walks. Single limb data are used toquantify limb function in body support, ac-celeration/deceleration, and lateral impulse.Supported by NSF-IBN 0080158.

S15.4WILLIAMS, J.B.*, TIELE-MAN, B.I.,Ohio State University, Columbus, Universityof Groningen, Netherlands. Evolutionaryphysiology of larks.

Conventional wisdom holds that arid-zone birds occupy these climes because ofthe possession of physiological design fea-tures common to all members of the classAves. Using broad scale comparisons, wetested the idea that desert birds have re-duced energy expenditure and water losscompared to mesic counterparts. We showedthat desert birds have a reduced basal meta-bolic rate (BMR), a reduced field metabolicrate, and a lower total evaporative water loss.Conventional analysis of covariance indi-cated that desert birds have reduced waterflux in the field, but an analysis based onphylogenetically independent contrasts did

not support this finding. We further searchedfor physiological specialization amongstmembers of the Alaudidae from mesic habi-tats in the Netherlands and from arid habi-tats in Saudi Arabia. Using DNA sequencesfrom the mitochondrial b gene, we con-structed a phylogeny of larks from Europeand from the Middle East, and then selectedspecies for physiological studies based onour results. We found that BMR and TEWL isreduced in larks from deserts compared tolarks from more mesic areas supporting ourhypothesis of evolutionary specialization.The evolutionary significance of our findingthat BMR and TEWL is reduced in desertbirds remains unresolved because differ-ences may result from physiological accli-mation, from genetic sculpting by naturalselection, or from a combination of both. Weconducted an experiment on the phenotypicflexibility of BMR in Hoopoe Larks fromArabia. We exposed groups to either 15oCor 36oC for 3 weeks. For larks in the 15oCgroup, BMR averaged 142% higher thanlarks in the 36oC group, a result attributable,in part, to a larger kidney, liver, and smallintestine. Similar experiments are in progresson larks in the Netherlands.

63.4 WILLIAMS. J.*, BIESIOT, P.M., Univer-sity of Southern Mississippi Gulf Coast Cam-pus, Institution: University of Southern Mis-sissippi, Hattiesburg. Fatty acid profiles as-sociated with diapause egg production intwo species of freshwater calanoid copep-ods.

The copepods Aglaodiaptomus (=Diaptomus) Stagnalis and A. clavipoides co-occur in certain ephemeral ponds. Both spe-cies hatch from diapause (resting) eggs whenpond sediments are freshly inundated andmature rapidly to adults. Both are believedto be univoltine, producing resting eggs only.In order to understand how diapause eggsare sustained during a potentially long dor-mancy, lipid classes and fatty acid profiles ofthe two species were compared. Our previ-ous study showed that female A. stagnaliswith egg sacs had higher concentrations ofspecific fatty acids compared to females with-out eggs. The specific objective of thepresent study was to determine if essentialfatty acids, required for growth and develop-

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ment of all animals, are preferentially mobi-lized from females to their eggs. Males, non-gravid females and gravid females wereassayed; egg sacs containing developingdiapause eggs were removed from gravidfemales so th! at eggs and mothers wereanalyzed separately. Our results confirm thathigh concentrations of specific fatty acids areincorporated into the diapause eggs of A.stagnalis but not of A. clavipoides. In theformer species, concentrations of both lino-lenic (18:3w3) and linoleic acid (18:2w6) arehigher in eggs than in females which in turnhave higher concentrations than males.However, all life history stages of A.clavipoides have similar concentrations ofthese two fatty acids. Although concentra-tions of omega-3 fatty acids are generallyhigher in eggs of A. stagnalis than in adults,concentrations of the essential fatty acidseicosapentaenoic acid (20:5w3) anddocosahexaenoic acid (22:6w3) are lower.In contrast, concentrations of these fatty ac-ids are similar in eggs and adults of A.clavipoides.

40.4 WILLINK, P.W., Field Museum. The in-tertwining influences of prey, head shape,and attack behavior on gill raker morphol-ogy.

Gill rakers are believed to play a criticalfunction during the feeding of fishes. The pre-dominant view is that gill rakers strain preyfrom the medium. Long, closely-spaced gillrakers are correlated with feeding on smallprey, whereas short, widely-spaced gill rak-ers are correlated with feeding on large prey.However, this view may be too simplistic.Based on data from sunfishes (Perciformes:Centrarchidae), it will be argued that gillraker morphology is dependent not only onprey size, but also on the interdependentfactors of attack behavior and mouth struc-ture. Species which ram feed tend to havelarger mouths and hence longer gill rakers.The opposite is true for suction feeding spe-cies. Differences in the pattern of water flowpast the branchial arches is hypothesized tobe the primary causal agent for the variousgill raker morphologies. These ideas mayhelp explain the feeding structures of north-western North America sticklebacks, GreatLakes coregonids, and many other fishes.

9.6 WILMHOFF, C. D.*, MCCLAIN, W. R.,GUTZKE, W. H. N., University of Cincinnati,The University of Memphis, The Universityof Memphis. The effect of temperature andstage of development on resting metabo-lism in an aquatic environment.

Organisms capable of reducing mainte-nance costs are able to invest a greateramount of energy into growth, body re-serves, and/or reproduction. In ectothermicorganisms temperature has repeatedlybeen demonstrated to affect resting metabo-lism, an indicator of maintenance costs. De-spite this wealth of information, the effect oftemperature on resting metabolism inplethodontid salamanders in an aquaticenvironment has not been examined. Thepresent study examined the resting metabo-lism of the adult and larvae of theplethodontid salamander, Eurycea junaluskain an aquatic environment across four ex-perimental temperatures (5, 15, 20, and25OC). Animals were acclimated to 20OC andresting metabolic rates were determinedusing a closed respirometry system. Adultsexhibited a significantly higher resting me-tabolism at 20OC and 25OC than larvae.There was no statistical difference in restingmetabolic rates of larvae between 5OC and20OC. Resting metabolism in adults exhib-ited a curvilinear increase with increasingtemperature.

P2.97WILMOT, A.*, DIDIER, D., WEBB, J.,University of Pennsylvania, Philadelphia, TheAcademy of Natural Sciences, Philadelphia,Villanova University. Morphology of the lat-eral line canals of the head in chimaeridfishes (Family Chimaeridae).

Most living chimaeroid fishes have aunique lateral line canal system consistingof open canals that appear as grooves onthe head and trunk. Members of the FamilyChimaeridae possess a unique canal mor-phology in which lateral line canals at theanterior of the head are enlarged with widedilations along the length of the canal and atcanal junctions. This characteristic is phylo-genetically significant at the familial level. Inan effort to explore the potential significanceof this character at lower taxonomic levels asurvey of 10 species of chimaerid fishes, 4species of Chimaera and 6 species of

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Hydrolagus, were studied. Canal distribu-tion and terminology was standardized andcanal dilations were counted. The numberof calcified rings supporting the canal be-tween dilations was counted in cleared andstained specimens. Scanning electron mi-croscopy and paraffin histology were usedto examine morphology and developmentof lateral line canals in embryos and juve-niles as well as determine the location of theneuromast organs within the canals. Num-ber of lateral line canal dilations is highlycorrelated to the size of the specimen andappears to have no significant taxonomicvalue; however, the pattern of lateral linecanals on the head and the morphology ofthe calcified rings are useful for distinguish-ing species. This detailed morphologicalstudy provides new characters for identifi-cation of species of chimaeroid fishes.

P1.97WILSON, B.*, MCWILLIAMS, S., Uni-versity Rhode Island, Kingston. Diet prefer-ences for certain fatty acids and its effect oncomposition of fat reserves in migratory red-eyed vireos.

Most birds accumulate large lipid storesas the primary source of energy for fuelingtheir migratory flights. The composition ofthese lipid stores varies among species;however, 16-carbon and 18-carbon fattyacids typically comprise 50-90% of the lip-ids. Palmitate (16:0) and oleate (18:1) areusually the predominant fatty acids in thedepot fat of migrating birds. We studied fattyacid preferences and the influence of dieton the composition of fat reserves in migra-tory red-eyed vireos using semi-syntheticdiets that differed only in fatty acid composi-tion. Using paired food-preference tests, wefound that daily food intake of red-eyedvireos was higher on diets containing triolein(18:1) than diets containing tristearin (18:0),higher on diets containing tripalmitin (16:0)than diets containing tristearin (18:0), andhigher on diets containing trimyristin (14:0)than diets containing tripalmitin (16:0). Dailyfood intake of vireos was similar on dietscontaining triolein (18:1) and trilinolein (18:2).These results suggest that red-eyed vireoscan discriminate between diets differing onlyin fatty acid composition and that they preferdiets with mostly long-chain unsaturated fatty

acids. We studied the effect of fatty acid com-position of the diet on the fatty acid composi-tion of fat reserves by maintaining vireos forone month on diets with different dietary fattyacids. The proportion of 16- and 18- carbonfatty acids in the depot fat of vireos was simi-lar to that of their diets. However, the pres-ence of very long-chain unsaturated fattyacids (e.g., 22:4, 24:5) in the depot fat ofvireos, despite its absence in the diets, sug-gests that selective metabolism of fatty ac-ids is also important in determining the fattyacid composition of depot fat in migratorybirds.

57.5 WILSON, C.M.*, HOLBERTON, R.L.,University of Mississippi, University of Maine.The endocrine basis for trade-offs betweenimmediate survival and reproductive suc-cess in arctic- and temperate-breeding yel-low warblers.

While temperate breeding birds canrenest or produce more than one success-ful clutch each year, Arctic-breeders are un-likely to raise more than one clutch annuallydue to shorter breeding seasons and un-predictable weather. Despite these con-straints, many birds successfully breed inthe Arctic, suggesting that trade-offs betweenindividual risk and reproductive success dif-fer between Arctic- and temperate breeders.The mobilization of higher plasma levels ofcorticosterone helps individuals survive en-vironmental perturbations, particularly forthose living in extreme and stochastic envi-ronments. However, high concentrations ofcorticosterone are incompatible with repro-duction. We have asked how high latitude-breeding birds with limited opportunities tobreed cope with the trade-off between thepersonal benefits of the corticosterone stressresponse needed in such an environment,and the possible cost in reproduction thatsuch a response may incur. In 1999 and2000, we found that Arctic-breeding maleYellow Warblers, who must contribute sig-nificantly to parental care, reduce acute cor-ticosterone secretion during times of high-est parental expenditure. The cost of this re-sponse to the individual and the mechanismby which it occurs are under investigation.Other temperate breeding species, to date,

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have not shown a similar reduction; samplesfrom temperate-breeding Yellow Warblersare currently being analyzed. If temperatebreeding males do not exhibit a similarlyreduced stress response, this phenomenonmay represent a mechanism by which twodifferent strategies expressed within thesame species might maximize reproductivesuccess under disparate ecological con-straints.

S9.5 WINGFIELD, J.C., University of Wash-ington Washington, Seattle. Endocrine re-sponses to unpredictable environmentalevents: stress or anti-stress hormones?

In addition to seasonal changes in mor-phology, physiology and behavior that oc-cur in predictable annual cycles, there arefacultative responses to unpredictableevents known as labile (i.e. short-lived) per-turbation factors (LPFs). These rapid behav-ioral and physiological changes have beentermed the “emergency” life history stage(ELHS) and serve to enhance life time fit-ness. Glucocorticosteroids interacting withother hormones in the hypothalamo-pitu-itary-adrenal (HPA) cascade, initiate and or-chestrate the ELHS within minutes to hours.Components of the ELHS include: redirec-tion of behavior from a normal life historystage to increased foraging, irruptive-typemigration during the day, enhanced restful-ness at night, elevated gluconeogenesis andrecovery once the perturbation passes. Thesephysiological and behavioral changes al-low an individual to avoid potential deleteri-ous effects of stress that may result fromchronically elevated levels of circulatingglucocorticosteroids over days and weeks.Several field studies in diverse habitats in-dicate that free-living populations have el-evated circulating levels of corticosteroidswhen in an ELHS. However, expression ofan ELHS may not always be advantageousand there is accumulating evidence frombirds that the adrenocortical responses toLPFs are modulated both on seasonal andindividual levels. These changes in respon-siveness to LPFs may have ecologicalbases such as reproductive state, body con-dition etc., that in turn may indicate differentcontrol mechanisms in the HPA cascade.Some simple models based on food avail-

able in the habitat, body condition, socialstatus and life history stage, may allow pre-dictions of sensitivity of the HPA axis to LPFs.

S15.8WINGFIELD, J.C.*, SOMA, K.K., Uni-versity of Washington, Seattle. Autumn andspring territoriality: same behavior, differentmechanisms.

Vertebrates show a diverse array of so-cial behaviors associated with territoriality.The mechanisms by which these behavioralpatterns are regulated by hormones are di-verse. Field and laboratory experiments in-dicate that general underlying themes - pos-sibly mechanisms - do exist. For example, inbirds, testosterone activates a type of ag-gression, territorial behavior, in those spe-cies that are territorial only during the breed-ing season. Territoriality at other times ap-peared to be independent of gonadal hor-mone control. One obvious question is - whythis diversity in control mechanisms ? Con-trol of testosterone secretion during thebreeding season must balance the need tocompete with other males and provide pa-rental care. Regulation of these behaviorsby testosterone in the non-breeding seasonmay incur substantial costs. The male songsparrow (Melospiza melodia morphna) ofwestern Washington State, is sedentary anddefends territories in both breeding and non-breeding seasons. Dominance interactions,territorial aggression and song during thenon-breeding season are essentially identi-cal to those during the breeding season. Al-though in the non-breeding season plasmatestosterone and estradiol levels are verylow, treatment with an aromatase inhibitordecreases aggression and simultaneous im-plantation of estradiol restores territorial be-havior. These data suggest that the mecha-nism by which testosterone regulates terri-torial behavior at the central cell level re-mains intact throughout the year. How thehormonal message to activate such behav-ior gets to the brain in different season does,however, appear to be different.

49.5 WINNE, C. T. *, KECK, M. B., StephenF. Austin State University, Nacogdoches TX.The historical evolution of thermal physiol-ogy in the diamondback watersnake,Nerodia rhombifer.

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We investigated three laboratory mea-sures of thermal physiology in the diamond-back watersnake, Nerodia rhombifer, alonga latitudinal gradient spanning 12 degreesin latitude and including individuals fromthree populations in Southern Texas (26,o

03'), one population in Central Texas (31,o

45'), three populations in Central Oklahoma(35,o 13'), and one population in Central Kan-sas (38,o 03'). Preferred body temperature,temperature-specific metabolism, and criti-cal thermal maximum were comparedamong the populations to determinewhether or not intraspecific variation in thesetraits provided evidence of local adaptationto respective climate regimes. Using thishistorical approach we apply our results inthe context of conservation, as an indicatorof the probability that N. rhombifer may beable adapt to future global warming.

P2.35WINNE, C.T.*, KECK, M.B., Stephen F.Austin State University, Nacogdoches TX.Daily activity patterns in Cnemidophorusinornatus and C. Septemvittatus: a pro-grammed behavior?

ABSTRACT- In field studies of activity andthermal biology of whiptail lizards (genusCnemidophorus: Teiidae), a strong correla-tion has been noted between daily activitypatterns and temperature: Cnemidophorusconsistently emerge from underground re-treats at particular soil temperatures, andthey retreat for a period of inactivity in thelatemorning or early afternoon when the soilreaches a particular high temperature. Pastresearchers have hypothesized that soiltemperatures were the proximate cue thatcontrolled daily activity. We experimentallytested this hypothesis, as well as hypoth-eses that hunger thresholds and high ratesof evaporative water loss influence dailyactivity patterns in Cnemidophorus, to de-termine if a causal relationship exists. Wefound that although a critical soil tempera-ture was required to elicit the initiation ofmorning activity in C. inornatus and C.septemvittatus, it was not a necessary stimu-lus for the cessation of activity. Access toprey, and thus hunger thresholds, did notinfluence the pattern of daily activity in thesespecies; moreover, evaporative water loss

did not appear to explain the cessation ofafternoon activity in these species. Revers-ing the photoperiods during our experimentsled only to a change in the time of initiationof daily activity (i.e., activity began 12 h later),not a significant change in the duration ofdaily activity. We hypothesize that daily sur-face activity in these lizards is a circadianrhythm controlled by a biological clock. Thebiological clock is entrained to the photope-riod and/or temperature cycle. Thus, dailyactivity in C. inornatus and C. septemvittatusceases relatively early without the influenceof changing environmental conditions.

P1.85WINSTEAD, C. J.*, CLAUSSEN, D. L.,Miami University, Oxford, OH. Cardiorespi-ratory responses of the asian prawn,Macrobrachium rosenbergii to temperatureand hypoxia.

Macrobrachium rosenbergii may experi-ence thermal and hypoxic stresses duringtheir commercial cultivation and duringtransport of stock or post-harvest animals.We used noninvasive methods to monitorcardiac responses, scaphognathite beating,and activity of juvenile and adult animalssubjected to cyclic temperature changesbetween 20 and 30 C. Half of the prawnswere further exposed to moderate hypoxia(2 - 4.5 ppm O2) during the experimental pro-tocol. Changes in heart width during the car-diac cycle were used to estimate stroke vol-ume and cardiac output. Diastolic heart widthexhibited a slight positive allometry with ascaling exponent of about 0.41. Overall, theeffects of hypoxia were small and those ofactivity were inconsistent; however, bothtemperature and body size had a substan-tial influence on cardiorespiratory responses.The mean Q10s for heart rate (1.73) weregreater than those for scaphognathite fre-quency (1.53). The Q10 response of heart ratewas greater between 25 and 30 C than be-tween 20 and 25 C, and this difference wasgreater for smaller than for larger prawns.The scaling exponents for heart rate aver-aged about -0.10. Unlike heart rates, esti-mated stroke volumes and cardiac outputsdid not respond to temperature in a consis-tent manner, but had mean scaling expo-nents of 1.09 and 0.99 respectively.Scaphognathite frequency responded to

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temperature, with scaling exponents of about-0.16. Giant Asian prawns are not overly sen-sitive to moderate hypoxia, and brief boutsof activity have only a modest impact on theirsubsequent cardiorespiratory responses.The prawns do not appear to be greatlystressed by temperature changes within the20 to 30 C range, but their cardiorespiratoryresponses, especially those of juveniles, areclearly influenced by temperature. Â

S15.1WOLF, B.O., University of New Mexico,Albuquerque. Using stable isotopes ap-proaches to explore animal physiologicalecology.

Stable isotope methods have been usedin a number of situations to study resourceuse by animals and rely on the observationthat the isotopic composition of an animalístissues reflects that of its diet. The stableisotope approach can also tell us about ananimalís physiological status. For example,in some cases carbon isotope analysis ofconsumer tissues can indicate the macro-nutrients being utilized and potentially wherethese nutrients are being routed to in theconsumerís body. Nitrogen isotope analy-ses of consumer tissues can provide addi-tional information about the nutritional sta-tus and trophic interactions of animal con-sumers. Carbon isotope analyses of breathcarbon dioxide can even provide informa-tion about macro-nutrient catabolism in al-most real time. Finally, the analyses of hy-drogen isotope composition of the body wa-ter pool of free-living animals may provideinformation on thermal stress, evaporativewater loss as a function of total water flux,and water resource use. Because of perva-siveness of fractionating processes in plants,animals and the environment, the stable iso-tope approach holds promise for examiningthe use and movement of specific macro-nutrients and the fate of water resources froma physiological perspective in free-living ani-mals.

P2.22WOLF, M.C. *, MOORE, P.A., BowlingGreen State University. Affects of the herbi-cide metolachlor on perception of chemicalstimuli by crayfish, Oroconectes rusticus.

Previous research has suggested thatcertain environmental pollutants interfere

with the perception of chemical stimuli. It isnot clear if the interference lies in maskingthe odor in the water itself or if there is aphysiological effect on the olfactory recep-tor cells that can influence the behavior ofthe animal. In this study we exposed cray-fish to the agricultural chemical Metolachlorin an acute fashion. We subsequently testedthe ability of the crayfish to perceive and re-spond appropriately to two chemical stimuliimportant to their survival, detection of dam-aged conspecifics and location of food re-sources. Results indicate that the behaviorof exposed crayfish toward odor is detrimen-tally changed. We conclude that there is anaffect on the ability of crayfish to perceivechemical signals after being exposed to thechemical Metolachlor and that this affectcould alter the ecology of this organism.

44.1 WOODARD, A.*, SHARDO, J., Univer-sity of South Alabama, Mobile. Morphologi-cal changes associated with the develop-ment of feeding in red snapper (Lutjanuscampechanus).

The formation of a functional feeding ap-paratus in larval teleosts is a finely tuned,functionally integrated set of processes. Weexamined the formation of the feeding ap-paratus in the larval red snapper from hatch-ing (22 hr postfertiliza-tion) through mouthformation (70 hr pf). Two developmental se-ries were collected (1997 and 2000) at theClaude Peete Mariculture Center (AlabamaMarine Resource Division, Gulf Shores) andexamined using scanning electron micros-copy and clear and stain techniques. Athatching (22-25 hr pf) the head has not liftedfrom the yolk and the larvae are lacking allbasic feeding structures. The larvae do notshow signs of mouth cavitation, nor jaw orvisceral arch formation, and the head re-mains attached to the yolk ventrally. Asposthatch development continues and thehead enlarges the yolk sac underlying thehead recedes exposing the ventral surfaceof the head (36-50 hr pf). The single oil drop-let moves caudally with the receding yolksac. Visceral arches form posterior to the opticvesicles on the ventrolateral surface of thelarvae, while the pharynx expands both an-teriorly and laterally (~50 hr pf). At about 60

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hr pf the mandibular arch splits and beginsto reorganize into upper and lower jaws (70hr pf). In conjunction with the complete ad-sorption of the yolk sac the stomodeum partsand the oral opening and the pharynx areconnected. Prior to complete adsorption ofthe yolk the mandibular arch and associ-ated mouthparts must become functionallyintegrated. This work supported through theEvaluation of Artificial Reef Modules(C900040005) to Robert L. Shipp and NSFgrant DEB-9707530 to Judith Shardo.

15.5 WOODLEY, S.*, PAINTER, D.,MOORE, M., WIKELSKI, M., Arizona StateUniversity, Tempe, Arizona State University,Tempe, Arizona State University, Tempe,Princeton University, NJ. Daily rhythm ofbasal corticosterone levels is not synchro-nized with feeding activity in marine igua-nas.

Basal plasma glucocorticoids (e.g., corti-costerone (B)) levels follow a circadianrhythm. The rhythm can be entrained byphotoperiod and food availability and func-tions in aspects of energy metabolism. Ma-rine iguanas (Amblyrhynchus cristatus) pro-vide a unique opportunity to better under-stand the rhythm of basal B levels because,unlike many vertebrates, feeding activity andphotoperiod are uncoupled. Animals feedin the intertidal zone so feeding activity isdetermined by the tidal cycle. Since ani-mals live at the equator, photoperiod remainsrelatively constant. If B modulates feedingactivity (or vice versa), then B should cyclewith feeding activity and not photoperiod.Basal B levels in free-living female Marineiguanas were measured every 6 hours over24 hours. We sampled again 1 week laterwhen the tide cycle was reversed, and hence,the feeding cycle was shifted. The pattern ofB levels between the two weeks was identi-cal, with a midday peak and a midnight low.Interestingly, the overall level of B was sig-nificantly higher the week when animals fedat midday, relative to the week when ani-mals fed either early in the morning or late inthe afternoon. To conclude, the rhythm ofbasal B is not entrained to feeding activity,but is instead entrained to photoperiod orsome process in phase with photoperiod.Because B levels peak at midday, we sug-

gest that B functions in energy metabolismassociated with basking. Basking is criticalto digestion and energy metabolism in ecto-therms, and is most efficient at midday whenthe sun is hottest.

47.2 WOURMS, J.P., Clemson UniversitySo. Carolina. Rudimentary trophotaeniae ofAtaeniobius embryos: an evolutionary in-termediate of teleost trophotaenial placen-tae.

Embryonic trophotaeniae, external hind-gut derivatives, and the maternal ovarianepithelium comprise the trophotaenial pla-centa of goodeid and other fishes. For 60years, Ataeniobius toweri was consideredthe only goodeid fish whose embryos lacktrophotaeniae. Scanning EM, however, re-veals three, external, rudimentarytrophotaeniae. Together, they form an hemi-spherical peduncle continuous with the hind-gut, bearing three lobes, one median dorsaland two lateral ventral. Trophotaenial cellshave microvilli whereas adjacent skin cellshave microplicae. Rudimentarytrophotaeniae are the terminal developmen-tal phase in Ataeniobius and are equivalentto those of Phase 2 embryos of Ameca, aspecies in which continued growth producestrophotaeniae 15 mm long. Ataeniobius rep-resents an intermediate stage in the evolu-tionary model: 1: Hindgut externalization; 2.Establishment of rudimentary trophotaeniae;3. Trophotaenial growth and morphogen-esis; 4. Trophotaenial ecodysis and anal re-modelling. (Supported by NSF).

P2.37A WRIGHT, K.L., KUCZAJ, S.; Univer-sity of Southern Mississippi, Hattiesburg. Theeffects of time of day on mother-infant asso-ciation patterns of bottlenose dolphins(Tursiops truncatus) in captivity.

Behavioral data on associationpatternsbetween mothers and their infantsare spares. This study compares the behav-ioral patterns of four mother-infant pairs overa two-month period. The data was collectedusing instantaneous sampling over a 24hourperiod at Marine Life Oceanarium. The pre-liminary analysis of these data indicate asignificant difference (Chi Squared, p>0.05)between nocturnal and diurnal associationpatterns. This difference is based on the fact

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that infants spend more time with their moth-ers at night than duriong the day.

S14.6WRIGHT, M.L., College of Our Lady ofthe Elms, Chicopee, MA. Circadian aspectsof hormonal regulation of metamorphosis inRana catesbeiana.

Most hormones exhibit a circadian, or 24-hr, rhythm synchronized by the light/dark (LD)cycle. Hormones such as melatonin (ML),adrenal cortical steroids, and prolactin maysynergize with, or antagonize, the thyroidhormones (TH) which induce metamorpho-sis. Consequently, the relationship of theirdiurnal profiles in the plasma with those ofthe TH might be important in controlling therate of metamorphosis. ML, which may dis-tribute a ìnightî signal and regulate hormonerhythms in vertebrates, declines precipi-tously in the plasma at climax coincident withthe rise in TH. The fall in plasma ML, which isinduced prematurely by exogenous thyrox-ine (T4), occurs in contrast to the rise of adre-nal corticoids and prolactin at climax. UnlikeT4 rhythms, which are stable throughout lar-val life, plasma corticoid and ML rhythmschange from prometamorphosis to climax.Thus, the relationship of ML and adrenal ste-roid rhythms with the T4 rhythm changesduring development. The acrophase of theT4 rhythms, and the diurnal profiles and cli-mactic changes of the corticoids and ML,are specific to each LD cycle. These, andother, results of ongoing work suggest thatthe influence of modulators on TH promo-tion of metamorphosis may havechronobiological aspects, which allow fine-tuning of the response to environmental con-ditions, and which might explain the varia-tions in the rate of metamorphosis that occuron different LD cycles, or when larvae aregiven exogenous hormones at different timesof the day. (Supported by NSF IBN9723858.)

P3.65WRIGHT, M.L.*, DUFFY, J.L.,GUERTIN, C.J., SZATKOW-SKI, M.C., Col-lege of Our Lady of the Elms, Chicopee, MA.Diurnal profiles of adrenal cortical steroidsin the plasma of bullfrog (Rana catesbeiana)tadpoles.

Adrenal cortical steroids may potentiatethe action of the thyroid hormones (TH) in

metamorphosis. The level of these hormonesin bullfrog tadpole plasma has been deter-mined at various metamorphic stages butthe diurnal rhythm has not been studied.Plasma corticosterone (CORT), hydrocorti-sone (HC), and aldosterone (ALDO) weremeasured over a 24-hr period. In both lateprometamorphic and early climax tadpoles,the corticoid rhythms in the plasma variedwith the light/dark (LD) cycle. On a given LDcycle HC and ALDO profiles were differentfrom each other at prometamorphosis, andboth rhythms changed at climax, when thediurnal profiles of all the steroids becamesimilar. The 24-hr mean, and the highest pointon the curves, were compared with resultsin the literature. CORT, which was only de-tectable at climax, and ALDO, values com-pared well with previous work but HC wasconsiderably lower than had been reported.On 18L:6D and 6L:18D, CORT was muchhigher than ALDO at climax, but these twocorticoids were nearly the same on 12L:12D.The results show the importance of conduct-ing measurements of plasma hormones ona defined LD cycle, and of sampling through-out a 24-hr day to obtain accurate estimatesof hormone levels at a given point in the lifecycle. (Supported by NSF IBN9723858.)

58.6 WYNEKEN, J.*, STEIN-BERG, F.,Florida Atlantic University, University MRI,Inc. The use of CT and functional MRI to ex-amine cardiopulmonary structure and func-tion in ecologically distinct species of turtles.

Sea turtles are secondarily aquatic aremigratory specialists. As such, they possesssuites of morphological, behavioral andphysiological adaptations for migratory life.These include unique sets of cardiopulmo-nary structures that may serve as adapta-tions for prolonged submergence while ac-tive. Through the use of Computed Tomog-raphy (CT) to map the extent of the lung andstructural and functional Magnetic Reso-nance Imaging (MRI and fMRI) the functionof the cardiopulmonary system can be ob-served in unanesthetized animals in anoninvasive manner. The CT and fMRI im-ages, plus dissections of fresh material, sug-gest the following. (i) The ventricles of seaturtle functionally separate systemic and

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pulmonary flow. (ii) The pulmonary arteriesintermittently profuse the lung while venousflow is more constant. (iii) When shuntingfrom the pulmonary to systemic systems oc-curs, several sites are involved (the ventricu-lar chambers, from the pulmonary circuit tothe systemic circuit via selective constrictionof the pulmonary arteries and at locationsbetween the pulmonary arteries and veins)suggesting control of perfusion at severallevels. Comparisons were extended to onespecies of nonmarine turtle (Trachemys), aless migratory and very shallow diving spe-cies. Observations to date reveal the pres-ence of no pulmonary shunts, a result thatsupports the hypothesis that pulmonaryshunting is dervived adaptation found indeep-diving and/or highly migratory aquaticturtles.

S2.7 YAMADA, G., Kumamoto University.Molecular analysis of murine external geni-talia formation: control of morphogenesis ofgenital tubercle by shh and Fgf system.

Recent gene KO studies have sug-gested that the developmental process ofthe anlage, the genital tubercle (GT), hasmuch in common with those of limb buds.However, except for some previous geneticstudies, systematic approach on severalregulatory molecules during GT formationhas not been performed. The shh and fibro-blast growth factor (Fgf) genes have beenpostulated as regulating several downstreamgenes during organogenesis. The Fgf8 genewas expressed in the distal urethral plateepithelium of the GT along with other markergenes expressed in the mesenchyme. TheShh gene was found to be expressed in theurethral plate epithelium. The urogenital ex-pression of the Shh gene was also reportedby Bitgood and McMahon. To functionallyanalyze the role of the FGF and shh systemduring GT formation, an in vitro organ cul-ture system was utilized. It was suggestedthat the distal urethral plate epithelium of GT,the Fgf8 gene expressing region, regulatesthe outgrowth of GT. The region was thussuggested as a candidate region for the sig-naling center during GT development. Ec-topic application of FGF8 beads to the mu-rine GT induced mesenchymal gene expres-

sion, and also promoted the outgrowth ofthe GT. Experiments utilizing anti-FGF neu-tralizing antibody suggested a growth-pro-moting role for FGF protein(s) in GT out-growth. In contrast, the Fgf10 gene appearsnot to be primarily essential for initial out-growth of GT despite its vital role during limbbud formation. Rather, the abnormal exter-nal genitalia development of Fgf10 mutantperinatal mice suggested the importance ofthe Fgf10 gene in the development of theglans penis and the glans clitoridis. Ourrecent analysis on FGF and shh system willbe presented. These data are expected tocontribute elucidating “ a model plan” fororganogenesis of external genitalia andother organs such as limbs.

P3.39YANG, C.*, CHENG, C.-H.C., Univer-sity of Illinois, Urbana-Champaign. Antifreezeglycoprotein genes in arctic cod: gene dos-age, structure, organization and evolution.

Antarctic notothenioids and northerncods are phylogenetically distant, but haveconvergently evolved near-identical anti-freeze glycoproteins (AFGPs) to survive intheir respective freezing marine environ-ment. We have previously shown thatNotothenioid AFGP gene evolved from apancreatic trypsinogen-like protease gene,and extant AFGPs are encoded by a largefamily of polyprotein genes. The evolution-ary ancestry and the organization of thenorthern cod AFGP genes remain to be de-termined. Our current studies on the AFGPgene family of the Arctic cod, Boreogadussaida, show that its AFGPs are also encodedby polyprotein genes, i.e. each gene en-codes a polyprotein precursor of multipleAFGP molecules connected in a series byconserved cleavable spacers (Arg). Ge-nomic library screening statistics and south-ern analyses of nine genomic clones to-gether indicate an AFGP gene family of asmany as 128 genes. Many of these genesare closely linked in the genome, some ofwhich are tandemly repeated. This high cod-ing capacity commensurates with the highAFGP protein level necessary for survival inthe very northerly geographic ranges of theArctic cod which includes the Arctic polarbasin. The evolutionary origin of the codAFGP gene remains elusive. We have iso-

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lated two clones from a partial library of anon-AFGP bearing freshwater cod, Lota lota,which shows sequence similarity to the up-stream and downstream sequence respec-tively of Arctic cod AFGP gene. Isolating andcharacterizing longer sequences of thesetwo clones may eventually shed light on theevolutionary mechanism that gives rise tothe first cod AFGP gene.

P3.101 YANG, P.-F., WANG, H.-Y., LEE, C.-Y.*, Natl. Changhua University of Edu. Involve-ment of 5- hydroxytryptamine-enhanced re-lease of crustacean hyperglycemic hormonein stress-induced hyperglycemia.

The objectives of the present study wereto investigate the effect of 5-hydrox-ytryptamine (5-HT) on the release of crusta-cean hyperglycemic hormone (CHH), andto determine if stress-induced hyperglyce-mia is mediated by 5-HT-enhanced CHHrelease. Eyestalk ganglia with intact X-or-gan/sinus gland complex were dissectedfrom the crayfish “Procambarus clarkii” andincubated under various experimental con-ditions. The incubation media were thenanalyzed for the presence of released hy-perglycemic factor using an in vivo bioas-say. The results show that 5-HT enhancedthe release of hyperglycemic factor in adose-dependent manner. The stimulatoryeffect of 5-HT was significantly decreasedby incubating eyestalk ganglia with 5-HT re-ceptor antagonist (ketanserin ormethysergide). Activity of the 5-HT-releasedhyperglycemic factor was reduced by ab-sorption of incubation media with ALPHA-CHH serum, but not by pre-immune or AL-PHA-5-HT serum. Furthermore, acute ther-mal stress (34ƒC) elicited hyperglycemicresponses in animals acclimated to 24ƒC.The thermal stress-induced hyperglycemiawas decreased in reserpine- (a 5-HTdepletor) or ketanserin-treated animals. Insummary, it is demonstrated that 5-HT en-hances release of CHH that in turns elicitshyperglycemic responses. The 5-HT-en-hanced CHH release is probably involvedin stress-induced hyperglycemia.

P1.43YIN, M.*, YANCEY, P.H., SarahLawrence College, Bronxville NY, WhitmanCollege, Walla Walla WA. Methylamine

osmolytes dominate in deep-sea polycha-etes, pycnogonids, and octopods.

Osmolytes of shallow-water marine in-vertebrates are usually free amino acidssuch as glycine, alanine, taurine. Recentlywe showed that some deep-sea crustaceansand molluscs are dominated by trimethy-lamine oxide, which can offset inhibition bypressure. Echinoderms and gastropodswere dominated by scyllo-inositol, whosecompatibility properties are unknown. Wehave continued analysis other deep-sea in-vertebrates, using HPLC. The followinganalyses note solutes that were 50 mmol/kgor greater, thus providing high osmotic pres-sure. Arm muscles of cirrate octopods (twospecies) were dominated by betaine(trimethylglycine) and taurine. Body wall andmuscles of polychaetes (two species: seamouse, and Travisia) were dominated by sar-cosine (methylglycine), betaine and scyllo-inositol; and leg muscles of one pycnogonidspecies contained mainly sarcosine. Methy-lamines may serve as pressure-counteract-ing solutes. To our knowledge sarcosine hasnot previously been reported at such highlevels in any animal. Supported by the Na-tional Science Foundation and M.J. MurdockCharitable Trust.

40.2 YOUNG, C. M.*, VAZQUEZ, E., HarborBranch Oceanographic Institution,Universidade de Vigo, Spain. How carnivo-rous deep-sea ascidians catch their prey.

Two new species of carnivorous deep-sea octacnemid ascidians have recentlybeen discovered at bathyal depths in theBahamas, one in the genus Dicopia and onein the genus Kaikoja. Analysis of gut con-tents indicates that both species consumemostly small crustaceans, though we alsoobserved entrapment of a small fish byKaikoja sp., the larger of the two. Becausethese animals have reduced branchial sacsand lack ciliated stigmata, they cannot filterparticles like other ascidians. It has beenwidely assumed in the literature that anoctacnemid traps prey like a Venus flytrapplant, closing rapidly on small animals thatcontact the inside surface of its incurrentsiphon. However, video observations froma submersible failed to reveal any instancesof food capture by rapid closure; instead,

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movements are generally slow and deliber-ate. Most individuals live on vertical rockwalls with the expansive incurrent siphonpointed downward and the small excurrentsiphon directed upward into the water col-umn. In situ studies with fluorescent dye re-vealed that internal flow is induced by ambi-ent currents in the benthic boundary layer.Passive flow draws prey into the incurrentsiphon, where they are unable to escapefrom reflexed folds of tissue. Once captured,prey are moved to the esophagus by rapidpumping of the body, which is accomplishedwith strong anterior muscles situated be-tween the siphons. These two octacnemidsare more like minnow traps than Venusflytraps.

S4.9 YOUNG, C.M.*, VASQUEZ, E., SVANE,I., Harbor Branch Oceanographic Institution,University of Vigo, Spain, Flinders Univer-sity of South Australia. Early life-history strat-egies of sessile invertebrates in stratifiedfjords and coastal lagoons.

The larvae of sessile marine animals arefaced with the difficult challenge of selectinga habitat that will be appropriate for the en-tire adult life. Many processes occurring inthe water column prior to settlement helpdetermine whether larvae will have the op-portunity to make an appropriate settlementchoice. Most ascidians are stenohaline ma-rine animals that penetrate short distancesinto water of low or variable salinity. In coastallagoons of Florida, the diversity of ascidiansis high near inlets but decreases rapidly asa function of distance from the inlets. In labo-ratory pycnoclines, larvae of colonial ascid-ians become inactive when swimming intobrackish surface layers. This causes them tosink toward the bottom where salinity is high-est. Metamorphosis is delayed or inhibitedin brackish water and species that are bestable to metamorphose at low salinities arealso able to penetrate into brackish portionsof the lagoons. In Gullmar Fjord, Sweden,most ascidians are found below the perma-nent pycnocline and few are ever found inbrackish “Baltic” water that lies above thepycnocline. Experimental transplants and labincubations indicate that adults of Ascidiellaspp. tolerate brackish water but that low sa-

linity inactivates or kills larvae and inhibitsmetamorphosis. A dense band of Ascidiellaaspersa found just below the pycnocline isexplained by flotation of embryos and by lar-val responses to the pycnocline layer. Theoccasional appearance of Ascidiella scabrain shallow water appears to result from short-term mixing events which coincide with timeswhen larvae are present in the water col-umn. In both the fjord and lagoon system,the tolerances and responses of ascidiansto low salinity change with ontogeny, andprocesses occurring in the embryonic andlarval phases help position the adults in ap-propriate salinity regimes.

P1.31YU, X.L.*, MYKLES, D.L., ColoradoState University. Cloning and characteriza-tion of skeletal muscle specific calpain fromlobster (Homarus americanus).

Crustacean muscles contain four cal-cium-dependent cysteine proteinases(CDPs or calpains) that differ in mass andsubunit composition. These enzymes (CDPI, IIa, IIb, and III) are involved in the degrada-tion of myofibrillar proteins during a pro-grammed atrophy associated with molting.We have begun cloning these genes to ana-lyze their expression in various tissues dur-ing the intermolt cycle. Highly degenerateuniversal calpain primers were designedbased on the homologous amino acid se-quences from multiple alignments ofcalpains from diverse species. Using nestedPCR and inverse PCR, a full-length (1978bp) lobster calpain gene (Ha-CalpB) wasisolated and sequenced from a deep ab-dominal muscle cDNA library. The deducedamino acid sequence of the polypeptide(about 55 kDa) has high sequence identityto other calpains, particularly the DrosophilaCalpain B (Dm-CalpB) gene. Domain I hasa unique N-terminal sequence of about 230bp; domain II consists of a highly-conservedcysteine protease sequence; and domain IIIcontains a unique stretch of 17 aspartatesand a highly-conserved Ca2+ -binding re-gion. Ha-CalpB, like Dm-CalpB, lacks acalmodulin-like sequence (Domain IV)found in the ubiquitous m-calpain and m-calpain in mammals. Northern blot and RT-PCR revealed that Ha-CalpB is highly ex-pressed in skeletal muscle, with little or no

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expression in other tissues. A polyclonal an-tibody raised against a unique amino acidsequence (residues 53-80) in Domain I isbeing used to identify which of the four lob-ster calpains is encoded by Ha-CalpB. CDPIIa (native Mr = 125 kDa; subunit Mr = 60kDa) and/or CDP III (native Mr = 59 kDa;subunit composition unknown) are poten-tial candidates. Supported by NSF (IBN-9904528).

11.4 ZANI, P.A.*, BRADSHAW, W.E.,HOLZAPFEL, C.M., LUCERO, K.D., Univer-sity of Oregon. The thermal tolerance of thepitcher-plant mosquito, Wyeomyia smithii.

We examined the pitcher-plant mosquito,Wyeomyia smithii, from three northern andthree southern populations to determine if alatitudinal gradient existed in their thermaltolerance. While many comparative studiesamong species have demonstrated a robustrelationship between thermal tolerance andprevailing temperature at the locality of ori-gin, we found within Wyeomyia smithii nodifferences in the critical thermal toleranceof mosquito populations spanning 30 to 46degrees North latitude. This lack of differ-ence in response to acute thermal stress isconsistent with earlier studies that found nogeographic difference in fitness in thesesame mosquito populations exposed tochronic lifetime thermal stress. Combinedthese results support the idea that the adap-tive modification of the thermal response isa slowly evolving process among animalsin nature.

67.1 ZELDITCH, M.L.*, SHEETS, H.D.,FINK, W.L., University of Michigan, Ann Ar-bor, Canisius College, Buffalo NY, Univer-sity of Michigan, Ann Arbor. Conservative on-togenetic trajectories: artifacts or data?

Most comparative studies support thehypothesis that ontogenetic trajectoriesarehistorically conservative. The primary basisfor this generalization is the typically highcorrelation between ontogenetic allometricvectors, a measure of their similarity. Morethan 76% of 233 comparisons yield vectorcorrelations as high as 0.96. However, thesecorrelations are misleading if taken to meanthat ontogenetic allometries are highly simi-lar, according to several lines of evidence.

Among these are the high correlations ob-tained from biologically absurd comparisons,such as between allometric coefficients of achimpanzee (based on cranial measure-ments) and a lizard (based on combinedcranial and postcranial measurements); thiscomparison yields a correlation 0.87. Also,correlations between randomly shuffled co-efficients and those based on actual datashould yield correlations near 0.0 but insteadyield correlations averaging 0.98 or higher.And correlations as high as 0.99 can beobtained by comparing allometric growthvectors to vectors of isometric growth, evenwhen growth is far from isometric. We sus-pect that correlations between ontogeneticallometric vectors may be high merely be-cause most taxa enlarge as they grow. Whenenlargement is removed from consideration,using geometric morphometrics, biologicallyabsurd comparisons yield correlations near0.0, as they should. And taxa that seem highlyconservative in their allometries, based ontraditional measurements, reveal consider-able repatterning of relative growth rates.

42.4 ZEPNEWSKI, E.*, NISHIKAWA, K.,Northern Arizona University, Flagstaff. Con-nective tissue in ballistic tongues.

Nerve transection experiments of themain tongue protractor muscle showed dif-ferences in feeding behavior between Ranapipiens and Bufo woodhousii. Bufowoodhousii shows a reduction in tongueprotraction length without directional devia-tion. The tongueof R. pipiens, while alsoshowing a reduction in extension, deviatestoward the intact side. We hypothesize thatthe differences in behavioral responses aredue to the amount and orientation ofepimysial connective tissue surrounding theprotractor muscle. Total amounts of collagenand elastin were measured for both spe-cies. Polarized light microscopy was used tomeasure the orientation angle of the col-lagen fibers surrounding the protractormuscle. Bufo woodhousii showed less con-nective tissue and fiber angles greater than54044’ which facilitates elongation. Thetongue of R. pipiens contains greateramounts of connective tissue and fiberangles less than 54044í which resists elon-gation. This fact, combined with the loss of

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angular momentum due to unilateral dener-vation of the protractor muscle, may accountfor the deviation seen in R. pipiens. Previ-ous studies have also shown Megophrysmontana to be an inertial elongator. Basedon normal feeding, we hypothesize collagenfiber angles in this species to also exceed540 44’ yet be less than B. woodhousii.Megophrys montana may represent an in-termediate between R. pipiens and B.woodhousii. Results from this study mayhave interesting evolutionary and ecologi-cal implications perhaps showing conver-gent evolution between distantly related taxa.

P3.21ZIGLER, K.S., Duke University. The seaurchin sperm protein bindin is conservedthroughout the echinoids.

The sea urchin sperm protein bindin isthe principal component of the acrosomalvesicle and is involved in sperm-egg recog-nition and sperm-egg fusion. Bindin is nothomologous to any known non-echinoidprotein. Bindin is only known from severalgenera of regular echinoids. We have clonedmature bindin sequences from a range ofother echinoids including a sand dollar(Encope stokesi), a heart urchin (Moiraatropos), a diadematoid (Diademaantillarum), and a pencil urchin (Eucidaristribuloides). The core region of bindin, whichis involved in sperm-egg fusion, is extremelyconserved. The regions flanking the core,which are involved in species-specificsperm-egg recognition, are remarkably di-vergent. These results indicate that thebindin molecule has been conserved in theechinoids for over 250 million years.

P2.75ZIMMERMAN, B.B.*, TOBALSKE, B.W.,Univ. of Portland, OR. Effect of flight distanceon take-off mechanics in zebra finch.

Flap-bounding is a flight style that is ex-pected to offer an aerodynamic advantageover continuous flapping at fast flight speedsbut not during hovering or slow flight. There-fore, we hypothesized that birds that exclu-sively flap-bound should maximize take-offvelocity to avoid slow flight speeds, regard-less of target flight distance. To test this pre-diction, we studied take-off in zebra finch(Taenopygia guttata, n = 6), a small flap-bounding species (14.8 g), as they flew dis-

tances from 2 to 10 m within a variable-lengthflight corridor. Horizontal and vertical groundreaction forces were obtained (5000 Hz)from a machined, instrumented, force perch,and synchronized high-speed video (1000Hz) was used to measure wing and bodykinematics. Generally consistent with ourhypothesis, flight distance did not have asignificant effect on the majority of the vari-ables examined. However, as flight distanceincreased, horizontal velocity at the end ofthe jumping phase of take-off increased, andvertical velocity decreased. The percent con-tribution of leg thrust to horizontal velocity atthe end of the jumping phase of takeoff alsodecreased significantly with an increase intarget flight distance. Thus, the wings con-tributed proportionally more to take-off ve-locity as the target flight distance increased.Overall, average horizontal flight velocity atthe end of take-off was 2.0 m/s. The mini-mum speed for which flap-bounding is pre-dicted to be aerodynamically advantageousto a zebra finch is 6.0 m/s; clearly, a zebrafinch must use additional wingbeats aftertake-off to reach this velocity. (supported byMurdock 99153)

P2.17A ZIMMERMAN, M.S., Biology De-partment, University of Michigan, Ann Arbor.Variation in brook stickleback (Culaeainconstans) size and shape associated withdifferent predator communities.

The present study explores the associa-tion of morphological traits of brook stickle-backs (Culaea inconstans) with two types ofpredator communities. Stickleback popula-tions associated with these predator com-munities differ in the size at which they arevulnerable to predation. My comparison ofbrook stickleback morphology involves 25populations in three adjacent river basins inMichigan’s upper peninsula. I hypothesizethat morphological variation among brookstickleback populations can be explained,in part, by different predation pressures. Toaddress my hypothesis, I compare age struc-ture and two aspects of morphology, sizeand shape, among brook stickleback popu-lations coexisting with each type of predatorcommunity. The results suggest that popula-tions vulnerable to predation as adults haveshorter-lived and smaller individuals than

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populations only vulnerable to predation asjuveniles in which individuals live longer andattain a larger size. Both mean and age-spe-cific body size differ among populations as-sociated with the two types of predator com-munities suggesting that predators affect bothgrowth rate and longevity of stickleback popu-lations. In addition, populations that are vul-nerable to adult predation have more fusiformindividuals with more caudally placed finsthan those vulnerable to juvenile predationonly. The results support the idea that mor-phological variation among brook sticklebackpopulations can be explained, in part, bypredator-prey interactions within each com-munity. Future work will investigate how on-togenetic investment in growth and shapediffers among brook stickleback populationsassociated with different predator communi-ties.

P3.58ZIVKOVIC, B.D.*, STEELE, C.T.,UNDERWOOD, H., SIOPES, T., NC StateUniversity, Raleigh. Critical photoperiod andreproduction in female japanese quail: roleof the eyes and pineal.

A previous study showed that removal ofthe eyes did not alter the stimulatory effect ofa long (e.g., LD 14:10) photoperiod on thereproductive response of female Japanesequail. The reproductive response to long pho-toperiods in the blind quail was mediated byextraretinal photoreceptors. The current study

was designed to test the role of the eyes andpineal in the reproductive response to photo-periods near the “critical” photoperiod; thatis, the minimum photoperiod required to drivethe reproductive response. In the first experi-ment, birds blinded by eye removal (EX) heldin LD 12:12 had a rapid onset of egg-layingwhile the intact controls did not exhibit egg-laying for up to 110 days. However, EX birdsresponded to a shortening of the photope-riod by ceasing to lay indicating that they re-mained photoperiodic. In the second experi-ment, groups of birds (intact, EX,pinealectomized, EX+pinealectomized, andoptic-nerve-sectioned) were exposed to in-cremental increases of photoperiod by 15minutes every 10 days, beginning with LD10:14. Various criteria were assessed to mea-sure the reproductive response including rateof response time to: onset of lay, 50% lay andmaximum lay. Optic-nerve-sectioned birdsconsistently required the shortest photoperi-ods, while pinealectomized birds consistentlyrequired the longest photoperiods, for all cri-teria. For some of the criteria EX birds re-quired shorter photoperiods than intact quail.The data indicated that the eyes are involvedin measurement of critical photoperiod andthat interrupting the neural output (optic-nerve-section birds) had a different effect thanremoval of both hormonal (melatonin?) andneural outputs (EX birds).

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