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Zygospore formation, germination, and theontogeny of the chloroplast of Sirogonium
In .P a r tia l F u lfillm en t of the R eq u irem en ts For the D e g re e of
MASTER O F SCIENCE
In th e G raduate C o lleg e
THE UNIVERSITY O F ARIZONA
1 9 6 5
STATEM ENT BY AUTHOR
T his th e s is has been su bm itted in p artia l fu lf illm en t of req u irem en ts for an advanced d eg ree at The U n iv ersity of A rizon a and is d ep o sited in the U n iv ersity L ib ra ry to be m ade a v a ila b le to b o rro w ers under r u le s of the L ib rary .
B r ie f quotations from th is th e s is a re a llow ab le w ithout sp e c ia l p e r m iss io n , p rov id ed that a ccu ra te acknow ledgm en t of so u rce is m ad e. R eq u ests for p e r m is s io n for extended quotation from or rep rod u ction of th is m a n u scr ip t in w hole or in part m ay be granted by the head of the m ajor departm en t or the Dean of the G raduate C o lleg e when in h is judgm ent the p ro p o sed u se of the m a ter ia l is in the in te r e s t s of sch o la rsh ip . In a ll other in s ta n ce s , how ever, p e r m is s io n m u st be obtained from the author.
A PPR O V AL BY THESIS DIRECTOR
T his th e s is has been approved on the date shown below:
ROBERT W. HOSHAW P r o fe s so r of Botany
2 7 !?cs~Date
ACKNOW LEDGM ENTS
The author w ish e s to e x p r e s s h is d eep est a p p rec ia tio n and
tn ost s in c e r e gratitu d e to Dr.. R ob ert W= Hoshaw for su g g estin g th is
p rob lem and for h is contin ued su g g estio n s and gu id ance throughout the
in v e s tig a tio n s and the w ritin g of th is m a n u scr ip t, I w ould a lso lik e to
thank him for the photographs for F ig u r e s 3 -7 , 16, and 18,
A p p rec ia tio n i s extended to E liza b e th P» F ra n tz and her
h o u seg u est from M unich, G erm any, F ra u U se H e lle re r , w h ose tr a n s la
tion s of p o rtio n s of De B ary (1858) and T rondle (1907) p ro v ed m o st
va lu ab le for the co m p letio n of th is w ork ,
. I am in d eb ted to R ich ard D, W aer, fe llo w graduate student in
the B otany D epartm ent, for the technique, of inducing m ovem en t of the
m a le g a m ete in S irogonium m ela n o sp o ru m .
Thanks a r e extended to D r, C h a r les T, M ason, D r. R ob ert S.
M ellor, and. Dro, W alter S., P h illip s for read in g and c r it ic iz in g the
m a n u scr ip t.
TA BLE O F CONTENTS
P age
LIST OF ILLUSTRATIONS „ . o „ „ „. , o „ . . „ „ . . . „ v
28o . A p ica l c e l l of the germ lin g shown in F ig u r es 22, 23, 24 54
BIST O F TABLES
T able
1.
20' .
3=
. 4 0
5„
60
7o
8.
9o
P age
Q u alita tive d if fe re n c e s betw een the gen era Sp irogyra andSirogonium a s co m p iled from the lite r a tu r e <> « o » o . o 5
G eograp h ica l d istr ib u tio n of 14 s p e c ie s of S iro g o n iu m 0 0 o 7
A v e ra g e m axim um , m in im um , and m ean te m p era tu res (in d e g r e e s F a h ren h eit) for the Sonoran D e se r t sta tio n at G uaym as,, S o n ., M exico from 192 3 -1 9 3 8 < , . . < > o . „ 17
A v era g e m onthly, s ea so n a l, and annual r a in fa ll at G uaym as,S o n . , M exico , in in c h e s . . . . . . . . . . . . . . o 17
A v era g e sea so n a l and annual r a in fa ll in e a s t and w e s tUttar P rad esh ,. India, in in c h e s „ « . . = o . . . . . 18
A v e ra g e m onthly, sea so n a l and annual r a in fa ll at G reen v i l le , M iss is s ip p i, in in c h e s . . . . . . . . . . . . . . . 18
D im en sio n s of cu ltu ra l z y g o sp o re s 2 hr a fter rew ettin g . . 34
C ell len g th s, a v e ra g e c e l l len gth s, and g r e a te s t w idths at s u c c e s s iv e s ta g e s of grow th of a cu ltu ra l gerrrding of
. S irogonium m elan osp oru m . . . . . . . . . . . . . . 45
S e le c te d c e l l len g th s, a v e ra g e c e l l length s in clu d in g a ll d e le ted c e l l le n g th s ,. and g r e a te s t w idths at s u c c e s s iv e s ta g e s of grow th of a natural germ ling of S irogon ium m elan osp oru m . . . - ., . . . . . . . . . . . . . . . 46
v ii
ABSTRAC T
Two h o m o th a llic c lo n e s of S irogonium m elan osp oru m (Randhawa)
T ra n sea u (1944) w e r e is o la te d from a s ite 7» 5 m ile s (120 I km ) w e st
n orth w est o f Guay m a s, Sonora, M ex ico 0
The ob ject of th is in v e stig a tio n w as to d e v ise a m eth od by
w hich the co m p le te life c y c le of th is Z ygn em atacean a lga cou ld be
fo llow ed , and to o b se r v e and r e c o r d th e accom panyin g ev en ts of th is
c y c le e S p ec ia l em p h a sis w as g iven to the p ro b lem s co n cern ed w ith th e
d iso rg a n iza tio n and reo r g a n iz a tio n of the chi or op la s ts during g a m eto -
g e n e s is and e a r ly g erm lin g develop m en t, r e s p e c t iv e ly , and w ith the
germ in ation of the z y g o sp o re .
A llow ing the f ila m e n t-n e ts of S irogonium m elan osp oru m , c o n
tain ing m atu re z y g o sp o re s , to dry s lo w ly at room tem p era tu re and
rem a in dry for two to four w eek s b e fo re w etting w ith supernatant from
T h in gsh eim s o il-w a te r m edium and p la c in g them under f lu o r e sc e n t
lig h tin g .o f about 3, 200 lux, p ro v ed to be a s e ffe c t iv e for inducing
g erm in ation as any of the s e v e r a l tech n iq u es tr ie d . U sing the p r e c e d
ing m eth od only lim ite d germ in ation of the z y g o sp o re s from cu ltu re
w a s obtained .
. F ra g m en ta tion of the c h lo r o p la s ts o ccu rs in both the m a le and
fe m a le gam etangia during g a m e to g e n e s is and the ch lor o p la sts rem a in
v i i i
in fra g m en ts throughout g a m etic union3 z y g o sp o r ic m aturation^ and in
to the e a r ly s ta g e s of the developm ent of the germ lingo The f ir s t
sta g e s of c h io r o p la s tic r eo rg a n iza tio n a r e f in g e r - lik e p ro jec tio n s of
ch lo r o p la stic m a te r ia l extending from both s id e s of a c en tr a l band of
c h io r o p la stic fragm entso A s reo rg a n iza tio n con tin u es, th e cen tra l band
d im in ish es in s iz e and th e fin ger - lik e p ro jec tio n s b eco m e the stra ig h t
r ib b on lik e c h io r o p ia s ts of the m atu re v e g e ta tiv e c e l l of S irogon iu m 0
The a fo rem en tio n ed p r o c e s s e s occu r co n cu rren tly w ith c e ll d iv isio n up
to about the th r e e - to s ix - c e l le d sta g e of the develop m en t of the germ -
lingo The a p ica l c e l l r e ta in s d iso rg a n ized c h io r o p la stic m a ter ia l until
a m uch la ter s ta g e in the grow th of the germ lingo
INTRODUCTION A ND REVIEW OF LITERATURE
The genus S irogonium K uetzing (1843) nom=. c o n s , i s one of the
13 gen era p r e se n t ly in c lu d ed in th e fa m ily Z y g n em aceae (Randhawa,
I9 5 9 )9 or, a s i t i s known in the U nited S ta te s , the fa m ily Z ygn em ataceae
(T ran seau , I9 5 1 )0 T his sp e llin g d iffe re n c e i s a lso r e f le c te d in the nam e
of the ord er, Z y g n em a les (Randhawa, 1959), and Z ygn em a ta les (Sm ith,
1933),, In a cco rd a n ce w ith S ilv a (1962);the sp e llin g e s ta b lish e d by Sm ith
(1933) w ill be u sed throughout th is m a n u scr ip t. . The m e m b ers of th is
order can be d istin g u ish ed from a ll other g reen a lg a e by th eir la ck of
fr e e sw im m in g, f la g e lla te d g a m etes and sp o res; sex u a l rep rod u ction i s
a cco m p lish ed by the m ovem en t of am oeb oid g a m etes through, or w ith in ,
a tube, p e c tic sheath , or an envelop in g p e c tic m a s s (T ra n sea u , 1951)»
No. W ille in 1897, acco rd in g to Randhawa (1959), c la s s i f i e d the green
a lg a e into two m ajor grou p s, C onjugatae an d .C h lorop h yceae, b eca u se
of the v e ry d is t in c t iv e m eth od of rep rod u ction , conjugation , in the
fo r m e r . The C onjugatae, h ow ever, h ave as m uch in com m on w ith other
o rd ers in the C h loroph yceae a s th e s e o r d e r s have w ith one another.
T h ere fo re the C onjugatae a r e p r e se n tly c o n s id ered a s on ly an order
w ith in the la r g er group, C h lorop h yceae, by m any p h y c o lo g is ts (F r itsc h ,
1935; Sm ith, 1950; B old, 1957; S ilva , 1962). F . F . B lackm an and A . G.
T a n sley in 1902, a ccord in g to Randhawa (1959), u sed the term Akbntae
in r e fe r r in g to the Z y g n em a ta les b eca u se of the a b se n c e of f la g e lla on
the g a m e te s . A nother com m on nam e for th is ord er , u sed by F r its c h
a s la te as 1935, i s C onju gates.
The m em b ers of the fa m ily Z y g n em ataceae a r e m o re or l e s s
p erm an en tly fila m en to u s , u su a lly unbranched and la ck p o r e s in th eir
w a lls of c e l lu lo s e (Sm ith, 1950; T ran seau , 1951; Randhawa, 1959).
T h ese c h a r a c ter s d is tin g u ish th is fa m ily from the other two fa m ilie s .
M eso ta en ia cea e and D e sm id ia c ea e , in th is o rd er . M ost m em b ers of the
Z ygn em ataceae have a p e c tic la y er o u tsid e the c e llu lo s ic c e l l w a ll w hich
m ak es them s lim y or s lip p ery ; S irogon iu m , how ever, la ck s th is outer
la y er of p e c to se (W est and F r its c h , 1927; Sm ith, 1950; T ran seau , 1951;
: Randhawa, 1959). • Sm ith (1950) s ta ted that the c e l l w a lls w ere c y lin d r i
ca l in the Z ygn em ataceae but T ran seau (1951) w as m o re sp e c if ic and
sta ted that c y lin d r ic a l c e l l s o ccu rr e d on ly during v e g e ta tiv e growth,
w h erea s rep ro d u ctiv e s tr u c tu r es m ay be quite v a r ia b le in s iz e and fo r m .
C onjugation i s u su a lly through a tube, but th is i s not the c a se in the
genus S iroc lad iu m nor i s it sa id to be the c a se in the genus, S irogonium
(Randhawa, 1959)° - C onjugating c e l l s in the Z y g n em ataceae do not have
th e ir p ro top lasts, e sca p in g from the e n c lo s in g w all during gam etic union
(Sm ith, 1950), and the z y g o sp o r e s a r e fo rm ed e ith er in th e conjugation
tube or w ith in one of the gam etan g ia (W est and F r its c h ,. 1927; Randhawa,
1959). - A ccord in g to Randhawa (1959) the c h lo ro p la sts can be c la s s i f ie d
into one of four g en era l ty p es , (1) a s in g le a x ile p late,, (2) two p a r ie ta l
p la te s , (3) one to s e v e r a l s te lla te s tr u c tu r es and (4) one to m any sp ir a l
rib b on s. The genera. S irogonium and S p irogyra have the fourth type of
ch lo r o p la s tic s tru c tu re .
In a p u b lica tion tit led P h y co lo g ia G en era lis , K uetzing (1843)
e r e c te d the genus Sir ogonium basing h is b r ie f d escr ip tio n upon a s in g le ,
s t i l l va lid , and the on ly p r e se n tly r ep o rted E uropean sp e c ie s ,. Sir ogonium
Istic ticu m (E ngl, B ot, ) K uetzing, K u etzin g‘s d e scr ip tio n a s g iven by
2. B ew is (1925) i s a s fo llo w s; "S irogonium K uetz, 1843; C e llu la e v e g e -
ta tivae c y lin d r ic a e , sp o r ife r a e su b in fla tae o r c u lifo r m e s . F a s c ia e
chlorophylloSoie lo n g itu d in a les , p a r ie ta le s , le v ite r f le x u o sa e , nod osae
(p lerum que 2 -3 , r a r iu s 4 in quaque ce llu la ), granula a m y la cea 7 -8
in vo lu ta e , C opulatio gen u flexa , s in e tubo con n ex ivo , " It i s u n d erstan d
able, w ith such a b r ie f and g en era l d escr ip tio n , that the genus S irogonium
h as not been a ccep ted a s d istin ct from the genus S p irogyra by m any
p h y c o lo g is ts . The l i s t of co m p a r iso n s b etw eem S p irogyra and S irogonium
1, , R e fe r s to S ow erb y 's (J a m es B eC a rl) E n g lish B otany; or, . coloured. f ig u r e s of B r it ish P la n ts , w ith th e ir e s s e n t ia l c h a r a c te r s , syn on ym s, and p la c e s o f growth; to w hich w ill be added, o cca s io n a l r em a rk s by J am es E dw ard Sm ith , V o l, 35 (1813) of 36 V o ls , p, 1463 and the fa c in g c o lo r e d p la te . W hite and. Co, London, 1 7 9 0 -1 8 1 4 ,
2, L ew is (1925) has the fo llow in g footnote; "G rayJs (1821) d escr ip tio n of C h oasp is an ted ates K u etz in g ^ by 22 y e a r s , G rayl s d ia g n o sis i s a s fo llo w s; ‘C hoappis, T hallu s th read lik e , s im p le , tubula r , jo in ted , kneebent; coupling a t the bend, by a p er fo ra tio n in each jo in t, w hich tr a n sm its the gra n u les from one p lant to th e o th er, w h ere th ey form an e llip t ic spore; g ra n u les sc a tte r e d , - -N o t s l ip p e r y ,1"
4
(T ab le 1} i s co m p iled from De B ary (I8 5 8 )s L ew is (1925), F r its c h
(1935), Sm ith (195% T ran seau (1951 and Randhawa (1959)= The f ir s t
th ree c h a r a c te r s , . m orp h o lo g ica l an iso g a m y , sc a tte r e d conjugation , and
the a b sen ce of a p e c tic sheath , a r e probab ly the m o st r e lia b le in d i s
ting m shin g Sixogonium from S p iro g y ra . . N one of th e se c h a r a c te r s i s
m en tion ed s p e c if ic a lly in K u etzin g 's d escr ip tio n of the genus S irogonium
and only the th ird , a b sen ce of a p e c tic sheath , i s g iv e n .in G ray's
d e scr ip tio n of the genus C h oasp is w h ere he sta ted that the plant body i s
"not s lip p er y . "
T ra n sea u (1951) had the fo llow in g to sa y about the p r o c e s s of
conjugation in S irogon iu m ;
The d evelop m en t of th e g am etan g ia tak es p la c e on ly from c er ta in v e g e ta tiv e c e l l s sc a tte r e d s in g ly or in .p a ir s a long the f ila m e n ts . U su a lly the. progam etan g ia d iv id e in to two unequal gam etangia - - one sh ort and one long - -a n d food su b sta n ces accu m u la te in th em . . T h ere m ay be two d iv is io n s r e su lt in g in a la r g er gam etangium betw een two sh ort c e l l s . . D e B ary s ta ted that the f ir s t type of d iv is io n r e s u lte d in fe m a le and the la tter in m a le g a m etes; he c a lle d the sh o rt c e l l s " s te r ile . " H ow ever, the d evelop m en t of gam etan g ia i s h igh ly v a r ia b le in so m e c o l le c tio n s . A pp arently p roga m eta n g ia m ay conjugate w ithout d iv is io n . A ny of the sh ort c e l l s m ay b ecom e m a le gam etan gia and d iv isio n in to th re e c e l l s b e fo re conjugation i s far le s s freq u en t than d iv ision in to two unequal c e l l s . . A s a r e s u lt of the fle x in g of the gam etan g ia at the beginning of a conjugation, s u c c e s s iv e conjugation s in a p a rticu la r fila m en t a r e each w ith a d ifferen t f i l a m ent. C onjugated f ila m en ts thus form a tan g led n et.
The actu a l m ovem en t of the m a le g am ete through the p ore
betw een the gam etangia has,, ev id en tly , not been ob served ; at le a s t i t
has not been rep o rted in the lite r a tu r e . The next d e sc r ip t iv e m a te r ia l
5
T able 1. . Q u alita tive d iffe re n c e s betw een the g en era S p irogyra and Sirogonium a s co m p iled from the lite r a tu r e .
S p irogyra S irogonium
l . y M orp h olog ica l iso g a m y i s 1exh ib ited by m o st sp ecies*
2* In sca la r if or m conjugation it 2=is com m on for long se c tio n s of the two fila m e n ts to have n ea r ly ev er y c o n sec u tiv e c e l l conjugating*
3* A m u cou s or p e c tic sheath i s 3*present*
4* L a tera l co n ju g a tio n .is com m on 4*in m any sp ec ies*
5* G enuflection of th e f ila m en ts 5*at th e t im e of conjugation i s uncommon*
6* The ch lo r o p la s t(s ) i s (are) . 6* u su a lly sp ir a lly arranged*
7* P rogam etan g ia a r e not p r o - 7*duced p r ior to the fo rm a tio n of the gam etangia*
8* '(S terile" c e l l s a re u su a llylacking*
9* T h ere i s a w e ll d evelop edconjugation tube present*
M orp h olog ica l a n iso g a m y is exh ib ited by a ll d e scr ib e d sp ecies*
S ca la r ifo rm conjugation o ccu rs s in g ly or o c c a s io n a lly in p a ir s s c a tte r e d along the f ila m e n ts .
The f ila m en ts la ck a m ucous or p ec tic sh eath .
No la te r a l conju gation h as been rep o rted for any sp ec ies*
G en u flection of th e f ila m en ts at the tim e of conju gation i s quite com m on.
The c h lo r o p la s ts a r e u su a lly stra ig h t or n ea r ly so*
P roga m eta n g ia a r e often p r o duced p rior to the form ation of gam etan g ia .
8* " Sterile" c e l l s a r e often found ad jacent to the gam etan gia .
9* A w e ll d eve lop ed conjugation tube i s u su a lly absen-tS ..s
on the life c y c le of S irogon ium m en tion ed by m o st au th ors i s co n cern ed
w ith the z y g o sp o re . The z y g o sp o r e s a r e u su a lly e ll ip s o id but so m e
sp o r es in any p a r ticu la r c o lle c t io n a re a ls o ovoid a cco rd in g to T ra n sea u
(I951)o . Randhawa (1959) l is te d o n esp p ec ies S. ph acosporum with, le n t ic u
lar z y g o sp o r e s . . In a ll but two of the 15 r e c o r d e d s p e c ie s of S irogon ium ,
the sp o re w a ll is co m p o sed of th ree la y e r s but in S. hui and S.
v a n d a lu ren sis th e m edian w a ll i s d iv id ed into two la y e r s . It i s the
m edian w a ll w hich con ta in s the p igm en t and m ay be sm ooth or exh ib it
the c h a r a c te r is t ic orn am en tation . Both of th e se c h a r a c te r s a re im p o r
tant in defin ing s p e c ie s in : S irogon ium (T ran s eau, 1951). The co lor of
the m edian w a ll v a r ie s from y e llo w to brown or b lack .
The h igh ly v a r ia b le j). s t ic tic u m i s the m o st w id e ly d istr ib u ted
s p e c ie s of th e gen u s, being found in ! E u rop e , A s ia , A fr ic a , A u stra lia ,
South A m e r ica , Canada, and the U nited S ta te s . T able 2 i s co m p iled
fro m T ra n sea u (1951 )j Randhawa (1959), and r e c o r d s of c o lle c t io n s by
m em b ers of the B otany D ep artm en t at the U n iv ersity of A r iz o n a . It
su m m a r iz e s the d istr ib u tion of the other 14 s p e c ie s of S irogon ium .
T his ta b le i l lu s tr a te s the w id e d istr ib u tion of the gen u s S irogon ium but
i t a lso r e f le c t s the fa c t that th is genus has been found e x te n s iv e ly only
in th o se reg io n s w hich h ave been m o st thoroughly sea r c h e d . . It is quite
prob ab le that th is genus is m uch m o r e com m on than th e p r e se n t, known
d istr ib u tion w ould in d ica te .
7
T able 2<. G eograp h ica l d istr ib u tio n of 14 s p e c ie s of S irogon iu m ,
South N orthS p ec ie s A m e r ica A m e r ica A fr ica A s ia
cey lan icu m C eylon; Bom bay, & Madhya P „ , India
floridanum sou th w estF lo r id a
C apetown So A fr ica
hui K iangsi,. China
il l in o ie n s e L erna , 111,; e a ste r n O kla3
indicum Gorakhpur, Uttar P rad esh , India
in f latum
m egasp oru m near Quito, B astrop , Tex= E cuador
P ettad , north Gujerat,. India
Szechw an,China
m elan osp oru m G reen v ille ,M is So; near Guay m a s, Son. M exico
F yzab ad (F a iz a - bad), Uttar P r a d esh ,. India
phacosporum near M orelia , M ich, j M exico
near R angoon, B urm a
p seu d o - florid anum
V ila s county, W isco n sin
r e t ie ulatum K arnal D is tr ic t , Eo Punjab, India
tenu ius Cordoba, . O kla», T ex a s , A rgentina; A rk«, & F la . Mato G rosso,B ra z il
8
T able 2 --C o n tin u ed
SouthS p ec ie s A m e r ic a
N orth Am e r ic a A fr ic a A s ia
v a n d a lu ren sis V andalur, M adr a s State, India
v en ter sicu m V enter s - dorp, Trans v a a l, . South A fr ic a
Gorakhpur,- Uttar P. &
Ho shangabad M adhya P . , India
In O ctober of 1961 Bra. R ob ert Hoshaw of the B otany D ep a rt
m ent, U n iv ers ity of A r izo n a , c o lle c te d an a lga near G uaym as, Sonora,
M exico , w hich he la ter is o la te d in to c lo n a l cu ltu re . Two of th ese c lo n a l
cu ltu res su rv iv ed and m a te r ia l w as sen t to D r.-C o E„ Taft at Ohio
State U niver s ity . He id e n tif ie d th is a lga a s S irogonium m elan osp oru m
(Randhawa) T ran seau (1944}0 Randhawa (1938) c o n s id e re d th is org a n ism
to be only a su b sp e c ie s of S. v en ter sicu m but T ra n sea u (1944) r a is e d it
to fu ll sp e c if ic standing on the b a s is of i t s o v e r -a ll la r g er d im en sio n s
and it s darker c o lo r e d (b lack) z y g o sp o r e s . Randhawa (1959) a ccep ted
th is change.
Both T ra n sea u (1951) and Randhawa (1959) g iv e m uch the sa m e
d e scr ip tio n of th is s p e c ie s of S irogon iu m . S. m elan o sporum h as v e g e
ta tiv e c e l l s from 7 0 -9 0 m ic r o n s in w idth and from 1 4 0 -2 6 0 m icro n s
long, each contain ing from 6 -9 n ea r ly stra ig h t c h lo r o p la s ts . The c e l l s
a re sa id to conjugate d irec tly , i , e„ w ithout form ation of a conjugation
tube, and the gam etan g ia in fla te up to 12 0 -1 6 6 m ic r o n s . The m a le
g a m ete m o v e s through a p ore in the tube to fu se w ith the fe m a le g a m ete .
The young zygote d ev e lo p s in to a zy g o sp o re w hich has a brown to b lack
and v e r r u c o s e m ed ian sp o re w a ll. The m atu re zy g o sp o re i s u su a lly
e llip so id and 9 0 to 110 m ic r o n s w ide by 140 to 160 m ic r o n s long.
P r io r to the p r e se n t c o lle c t io n of S. m elan osp oru m from
M exico th is s p e c ie s had been rep o rted only from the r eg io n around
Fyzabad, Uttar P ra d esh , India, and near G reen v ille , M is s is s ip p i. In
the Indian habitat at the c lo s e of the sou th w est m o n so o n -b o rn e ra in s ,
th is a lga b eco m es abundant and p ro d u ces m atu re z y g o sp o r e s at the end
of Septem ber and duriiig the d r ier m onths of O ctober and N ovem ber
(Randhawa, 1959).
Som e authors have sta ted that it i s d ifficu lt or im p o ss ib le to
m ain ta in m em b ers of the Z ygn am ataceae in the la b o ra to ry (C ham berla in ,
1932; Johansen, 1940; B old, 1942) but s in c e the advent of P r in g sh e im 1 s
so il-w a te r m edium (P r in g sh e im , 1946) and i t s m o d ifica tio n by Starr
(1964) the cu ltu rin g of m any kinds of a lg a e has been g r e a t ly fa c ilita ted .
It w as the u se of th is m edium that en ab led A llen .(1958) to m ain ta in her
cu ltu res of S p irogyra for m any m onths during her study of a s p e c ie s
co m p lex in that gen u s. M any kinds of a lg a e , including m em b ers of the
Z ygn em ataceae, a r e m ain ta in ed co n tin u ou sly at the Indiana C ulture
C o llectio n of A lgae (S tarr, 1964).
10
■ A lthough it i s now m uch e a s ie r to grow a lg a e v e g e ta t iv e ly 9 it
i s s t i l l d ifficu lt to in d u ce th eir sex u a l c y c le for la b o ra to ry study. . One
of the le a s t un d erstood a sp e c ts of the l i f e c y c le of the Z y g n em a ta cea e
c en te r s around the zy g o sp o re , i t s v ia b ility and g erm in a tio n . A llen
(1958) had only lim ite d s u c c e s s in g erm in a tin g the z y g o sp o r e s of
s e v e r a l s p e c ie s of S p irogyra . T ron dle (1907) m ade e x te n s iv e stu d ies
of conjugation and g erm in ation in S p iro g y ra . He found that the z y g o
sp o r es of S. n eg lec ta en tered a " sta te of r e s t" andggerm inated only
after a p e r io d of about two m on th s. A cco rd in g to A llen (1958), H.
K lebahn in 1891 g erm in a ted z y g o sp o re s of two s p e c ie s of S p irogyra and
one of Z ygnem a after a llow in g them to overw in ter in the d ried condition ,
and g erm in a tio n of Z ygnem a s te llin u m w a s a cco m p lish ed by K urssanow
in 1 9 1 2 .by the add ition of f r e s h p eat w ater about one m onth after z y g o
sp ore fo rm a tio n . A cco rd in g to He B ary (1858) the g erm in a tio n of
Sirogonium z y g o sp o r e s (S. s t ic t ic u m ).w as f ir s t o b se rv e d in 1855 by
W ichura who sta ted that th eir g erm in a tio n w as c o m p le te ly analogou s to
the g erm in ation of the z y g o sp o r e s of S p iro g y ra . . He B a ry (1858) c o lle c te d
m atu re z y g o sp o re s and liv e f ila m en ts of S irogonium s tic tic u m in ea r ly
June, "cu ltured them in a room " and o b se rv e d the f ir s t g erm in a tio n s
in ea r ly O ctober, a p er io d of about four m onths a fter c o lle c t io n . . It i s
not c lea r w hether or not the cu ltu re w as kept in liquid m ediu m from the
tim e of c o lle c t io n through the tim e of g erm in a tio n of the z y g o sp o r e s .
11
M ore e x te n s iv e in form ation i s known about th e sex u a l cy b le s
of C hlam ydom onas (S tarr, 1949; L ew in , 1949, 1957; L ev in e and E b e r s -
old, 1958;: E ber so ld and L ev in e , 1959; L ev in e and F e ls o m e , . 1959;
G ow ans, I960 ),. C osm ariu m (S tarr, 1955, 1959), and Gonium (Stein,
1958)o . E rb en (1962) su m m a rized the p r e se n t sta te of kn ow ledge about
a lga l sp oru la tion and g erm in a tio n w ith the fo llo w in g w ord s: "By c o m
p a r iso n w ith the e x te n s iv e s tu d ies of the sp o r e s of fungi or b acter ia ,
h ow ever, th ere have been v e r y few c r it ic a l in v e s t ig a tio n s of the p h y s ic a l
and b io ch em ica l fa c to r s in v o lv ed in a lg a l sp oru la tion and germ in a tio n . "
T h ere a r e v e r y few r e fe r e n c e s in the lite r a tu r e w hich r e la te
the r o le p la y ed by the c h lo r o p la s t during th e life c y c le of any .m em ber
of the Z ygnem ataceae= . D e B ary (1858), Y ork ,(I913), and o th ers have
noted that th ere i s an accu m u lation of s ta r ch a s so c ia te d w ith the c h lo r o
p la s t p r io r to the p r o c e s s of conju gation . F r its c h (1935) sta ted that V.
C h m ieiev a sk y in 1890, and T rbndle in 1907 o b serv ed that the ch lo ro p la st
of the m a le gam ete , in S p irogyra , d is in teg r a te d at an e a r |y s ta g e .
A lthough De B ary (1858) im p lie d that the c h lo r o p la s ts of S irogonium
s tic ticu m w e re in. "shred s" which' " slow ly s tre tch out" during g erm lin g
grow th, he il lu s tr a te d a o n e -c e lle d g erm lin g w ith c h lo r o p la s ts fu lly
, d eve lop ed . A lle n 's (1958) figu res, a lso show fu lly d ev e lo p ed ch lo r o p la s ts
in o n e -c e lle d germ lin g s of S p iro g y ra . - A gain th is i s the c a s e w ith an
illu s tr a t io n by L ew is (1925) of h is T em n ogyra c o l l in s i i w h ich i s
12
c o n s id e re d by F r its c h (1935) and T ra n sea u (1951) to be only a s p e c ie s
of Spirogyrao
The p r e se n t study w as undertaken to e lu c id a te d evelop m en t
p rior to, w ith in , and im m ed ia te ly fo llo w in g the zy g o sp o re in
Sirogonium m ela n o sp o ru m .
M ATERIALS A ND METHODS
A d escr ip tio n of the c o lle c t io n s ite , the g en era l en v iron m en ta l
con d ition s and tech n iq u es of cu ltu rin g , and the sp e c if ic apparatus and
m eth ods of in v e stig a tio n a r e g iven below*
. C o llec tio n S ite
The o r ig in a l c lo n e s of S irogon ium m elan osp oru m u sed in th is
study w e re is o la te d by Dr * R obert W, Ho s haw from m a te r ia l c o lle c te d
on 18 O ct.T 96l from a sm a ll pond w h o se in term itta n ce i s d eterm in ed by
the ir r e g u la r su m m er and w inter ra in s o ccu rr in g in th is region* The
pond, w hich i s 7*5 m ile s (12* 1 km ) w e st n orth w est of G uaym as,. Sonora
M exico i s lo ca ted on the seaw ard s id e of the road lead in g from M exico
highw ay no. 15 to the r e s o r t a rea of San C a r lo s Bay about 3 m ile s (4 . 8
km ) w e st of the pond. . The pond i s 4 . 7 m ile s (7 . 6 km ) w e st of the tu rn
off to San C arlos B ay (Map, F ig . 2). . It i s only 150 to 250 y d s . south
and over the beach dunes to the sa lty w a te rs of the Gulf o f C a liforn ia
but the pond i t s e l f i s f i l le d w ith fr e s h w ater during the ra in y sea so n .
F ig u re 1 show s the c o lle c t io n s ite . The so il at th is s ite i s a fin e
tex tu red sandy c la y . The photograph, taken in. A p ril of 1963 p r io r to
the sum m er r a in s , show s the dry pond bottom . The car in the b ack
ground i s p ark ed on the r oad to S a n C a r lo s Bay w hich i s to the le ft (w es
F ig u re 1. . C o llec tio n s ite .
14
Fig. 1
Fig. 2
M AP OF COLLECTION SITE
to hermosillo 7 9 mi.
i ® " # fAmmC°15
ensenada san francisco
California
4
. 16
The a ir tem p era tu res p rev a ilin g at G uaym as a r e g iven in
Table' 3= The annual a v era g e p r ec ip ita tio n at G uaym as, by m onths and
s e a so n s a s co m p iled from the A m e r ica n A utom obile A ss o c ia t io n (1963)
i s g iven in T able 4„ • A footnote sta ted that the f ig u r e s r e p r e se n te d an
a v era g e over at le a s t a 5 -y e a r p er io d but the dates of th is p er io d w e re
not g iv en . The G uaym as reg io n i s a c o a sta l d e se r t w ith ra in s p r im a r ily
in the sum m er but th ese a r e quite sp orad ic and long p e r io d s of drought
la stin g through s e v e r a l s e a so n s a re not uncom m on (S h reve, 1964).
. The sea so n a l ra in fa ll in the other two h ab ita ts w h ere S irogonium
m ela h o sp o ru m .is known to occu r, i s g iven in T ab les 5 and 6 for c o m
p a r iso n and d is c u s s io n in a la ter sec tio n of th is m a n u scr ip t. T h ese
habitats a re Uttar P ra d esh , India (T ab le 5) and G reen v ille ,. M is s is s ip p i
(T able 6).
- Iso la tio n
With the u se of fin e g la s s p ip e tte s , p ie c e s of r e la t iv e ly c lea n
f ila m en ts about 4 or 5 c e l l s long w e re placed into w atch g la s s e s w hich
w e re f i l le d w ith supernatan t from ste a m ed so ii-w a te r m edium or s t e r i le
w a ter . The w atch g la s s e s w e re supported by tr ia n g le s of bent g la s s
tubing in p e tr i d ish e s . A ll the g la s sw a r e w as a u to c la v ed at 15 lb s .
p r e ssu r e for 15 m in . p r io r to u se . • A fter s e v e r a l tr a n s fe r s through
fr e s h liq u id contained in c lea n w atch g la s s e s and a g ita tio n to fu rth er
c lea n the f ila m e n ts , ea ch p ie c e w as f in a lly tr a n s fe r r e d to a sep a ra te
T able 3° A v era g e m axim um , m inim um , and m ean tem p era tu res in d eg rees F ah ren h eit for the Sonoran D e se r t sta tion at G uaym as, Son=, M exico from 1 9 2 3 -I9 3 8 0 C om piled from
. Sh reve (1964 )o
___________________ Jan* . Febo M ar». A p ro . May Jun.. Juh A ug. . Sep* . O ct. Novo . D ec. Y ear
M axim um 72 70 75 76 82 87 92 88 87 84 76 70 7 9 .5
M inim um 60 63 66 70 75 83 85 84 84 79 70 63 7 3 ,4
The trea tm en ts u sed in an attem p t to ind uce a c o n s is ten t
am ount of g erm in a tio n in cu ltu ra l z y g o sp o r e s , d e sc r ib e d on page 2 2
of th is m a n u scr ip t, w e r e la r g e ly u n su ccessfu l* L e s s than 5% g e r m i
nation w as obtained from th o se sp o r es w hich , m o rp h o lo g ica lly , ap p eared
to be viable* O ften not a s in g le sp o re in a p articu lar net w ould g e r m i
nate r e g a r d le s s of the trea tm en t it underwent* B ec a u se of th is v e r y
low and e r r a tic g erm in a tio n no s ta t is t ic a l c o m p a r iso n s cou ld be
m ade am ong the v a r io u s treatm en ts* G erm ination of one or m ore
zy g o sp o re s did occu r, h ow ever, in so m e d ish es contain ing nets g iven
a p r io r -to -w ettin g h eat trea tm en t, in n e ts g iven an a fter -w e ttin g h eat
trea tm en t, and in th o se n ets w hich w e r e s im p ly w et at room te m p e r a
tu re and p la ced under f lu o r e sc e n t ligh tin g . No g erm in a tio n o ccu rred
in any of the other d is h e s . The r ea so n for the p a r tia l e f fe c t iv e n e s s of
drying fo llo w ed by w etting for inducing germ in ation of th e z y g o sp o re s
has not been d eterm in ed . The g erm in a tin g z y g o sp o r e s d e h isc ed in a
regu lar fa sh io n o n e-h a lf to th r e e -fo u r th s the length of the sp o re .
, A lthough the d e h isc en ce w a s quite reg u la r , no lin e of d e h isc en ce w as
ever v is ib le in th e s e sp o r e s b e fo re the actu a l sp littin g at th e tim e of
germ in a tio n . Z y g o sp o res , w hether or not th ey germ in a ted , sw e lle d
som ew hat a s th ey im b ib ed w ater upon b ein g w e t te d .. A n o ticea b le change
in co lo r from brown to g reen o ccu rr e d in a ll th o se z y g o sp o r e s w hich
w ent on to germ in ate; how ever not a ll the z y g o sp o re s w h ich changed
co lo r germ in a ted . M ost g erm in a tio n o c cu rr e d w ith in 4 8 -7 2 hr a fter
w etting , but in a few c a s e s g erm in a tio n o ccu rr e d up to 14 days after
w ettin g . T w ice zy g o sp o re s g erm in a ted in n ets w hich had been w etted ,
r ed r ied , and w etted again . . Z y g o sp o res from the M ex 22 so il sam p le
a ls o d em o n stra ted th is d ifferen tia l g erm in a tio n .
G erm ination of z y g o sp o re s fro m cu ltu ra l m a te r ia l o ccu rred
w h ile the zy g o sp o re s w e r e s t i l l con ta in ed w ith in the o ld fe m a le
gam etan g ia l w a lls (F ig s . 16, 18). D is se c t in g the z y g o sp o r e s out of the
gam etan g ia did not in c r e a s e the p e r ce n ta g e of g erm in a tio n . . C ultural
36
z y g o sp o re s m o r e than one yea r o ld and n atural z y g o sp o r e s m o re than
two y e a r s o ld have g erm in a ted after rew ettingo
G erm ling and R eo rg a n iza tio n of the G h lorop lasts
The p ro to p la st of the z y g o sp o re , e n c lo se d by th e inner thin
e la s t ic c e l lu lo s ic sp o re w a ll, e m e r g e s through a rup tu re in the m ore
r ig id m ed ian and outer w a lls . T h ese w a lls a r e o c c a s io n a lly ir r e g u la r ly
torn at the end but m o st often they d e h isc e along a v e r y reg u la r lin e
(Figs<, 18, 21)o A s h as been m en tion ed e a r lie r , th is lin e of d e h isc en ce
i s not v is ib le p r io r to the g erm in a tio n of the z y g o sp o r e c . The lin e of
d e h isc en ce of the zy g o sp o re in F ig u re 11 w as som ew h at d is to r ted by
m an ipu lation s w h ich m oved the o n e -c e l led g erm lin g out of the sp ore
w a lls for photographic p u rp o se s .
The o n e -c e lle d g erm lin g con ta in s s ta rch and o il d ro p le ts , . In
cu ltu ra l m a te r ia l th e se su b sta n ces r a r e ly o b scu re the d is s o c ia te d
ch lo ro p la st in the young g erm lin g (F ig s , 11, 12, 17, 18), A c lu s te r of
orange g ra n u les i s often v is ib le in the o n e -c e lle d g erm lin g (F ig , 12), .
The author h as not d e fin ite ly d e term in ed w hat th e se g ra n u les r e p r e se n t
but a d is c u s s io n .o f th eir p o s s ib le o r ig in w ill be found in th e fo llow in g
sec tio n of th is m a n u scr ip t. The orange gra n u les occu r in young g e r m -
l in g s of both natural and cu ltu ra l z y g o sp o r e s , but th ey a r e not a lw a y s
r ea d ily v is ib le , . A s the g erm lin g in c r e a s e s in length , by c e l l d iv is io n ,
the gra n u les b eco m e le s s and le s s co n sp icu o u s and a r e even tu a lly lo s t
37
from v iew . , By the t im e the g erm lin g i s about 15 c e l l s long or e a r lie r
the gra n u les a r e no lon ger ev id en t.
E ven s in g le -c e l le d germ lin g s p r e se n t a v a r ie ty of a p p earan ces
w ith r e s p e c t to shape, w idth, and length . The c e l l s a r e u su a lly m o re
or l e s s e lon gate and th ey m ay or m ay not have a co n sp icu o u s bend (F ig s .
11, 12, 16). The g erm lin g ssa t th is point m ay fo llow e ith er of two g e n
e ra l p lan s of d evelop m en t. The o n e -c e lle d g erm lin g m ay begin to d iv id e
im m ed ia te ly b e fo re e x te n s iv e c e l l e lon gation , producing a fila m en t of
sh ort c e l l s , or the o n e -c e lle d g erm lin g m ay e lon gate g r ea t ly b efore
the f ir s t c e l l d iv is io n producing a f ila m en t w ith a long tap erin g b asa l
c e l l and subsequent c e l l s w hich a re m o r e e longate tiian th o se of the f i r s t
p lan . The f ir s t p attern i s the one m o st often o b serv ed in g e rm lin g s p r o
duced from cu ltu ra l z y g o sp o r e s and the seco n d p attern i s m o st often
found in g e rm lin g s p rod u ced from natural z y g o sp o r e s . T h ese two
p a ttern s do not r em a in d is tin c t . A s the g e r m lin g s grow , the c e l l s of
the fila m en t, other than the b a sa l c e l l and th o se c e l l s ad jacent to it,
look v e r y m uch a lik e w hether the g erm lin g i s one from cu ltu ra l or
natural z y g o sp o r e s . A cu ltu ra l, th r e e -c e l le d g erm lin g of the f ir s t type
i s shown in F igur e 17 and two n atural four - c e l le d g e r m lin g s of the
secon d typ e a r e shown in F ig u r e s 19, 20. T h ese d is tin c tio n s a re not
ab so lu te . A r e la t iv e ly long b a sa l c e l l in a cu ltu ra l g e rm lin g i s shown
in F ig u r e 18 and a r e la t iv e ly sh o rt b a sa l c e l l in a natural g erm lin g i s
show n in F ig u r e 21. The b a sa l p ortion of the g erm lin g u su a lly r em a in s
38
w ith in the zy g o sp o re :" ca se" (F ig S o - 1 7 -2 2 ) . The g e r m lin g s shown in
F ig u r e s I I , 17 w e re te a se d out of the z y g o sp o re c a s e s in order to obtain
photographs of the en tire c e l l ( s ) . The zy g o sp o re c a s e s s e e n in th ese
f ig u r e s w e re both d is to r ted during th is p r o c e s s of teasingo
The n u cleu s w as not v is ib le in o n e -c e lle d g e r m lin g s , but w as
u su a lly v is ib le in both c e l l s of the tw o -c e lle d s ta g e . A fter the f ir s t
d iv is io n in th e g erm lin g , both c e l l s h ave the p oten tia l for further
d iv is io n and grow th but the b a sa l c e l l d iv id es only r a r e ly w h erea s the
a p ica l c e l l and it s d e r iv a tiv e s d iv ide freq u en tly . The b a sa l c e ll , w hether
or not it d iv id es a fter th e f ir s t d iv is io n , e lo n g a tes g r e a t ly and con tin u es
to do so ev en after the young germ lin g has d evelop ed to 35 c e l l s or m o re
in .len g th . The b a sa l c e l l m ay, in tim e , b ecom e d is to r te d and die, p r o b
ably due to in jury in f lic te d upon it by the m ech a n ica l s t r e s s e s of the
dividing and elongating c e l l s of the young fila m en t. G erm lin g s seld om
e m e rg e from their c a s e s a s sh ort s tra ig h t f ila m en ts co m p o sed of c e l l s
of uniform w idth . In young, g e rm lin g s ,. e sp e c ia lly th o se from natural
z y g o sp o r e s , the c e l l s grad u a lly in c r e a s e in w idth up to the filam en t
m axim um o c cu rr in g ,a t about the fourth to tenth c e l l . The m axim um
width, on ce it i s r ea c h e d by the young g erm lin g , r e m a in s r e la t iv e ly
constanitthroughout th e fu tu re grow th of the fila m en t. The fila m en t m ay
again taper a l it t le at the a p ica l end. The ap ica l c e l l i s n ea r ly a lw ays
I 1 /3 to 2X a s lo n g ,as any one of the next, few c e l l s c lo s e s t to it (F ig s .
22, 23, 24; T ab les 8, 9).
39
The bending of a fila m en t m ay be s lig h t as show n in F ig u re 13
or it m ay be m o re e x te n s iv e a s show n in F ig u r e s 17, I 8 0 The bends,
once they a r e form ed , a r e not sta tic but m ay, and often do change as
the c e l l s of the fila m en t d iv ide and e lo n g a te . The in it ia l bending of the
fila m en t is often the r e su lt of con fin em en t of the g erm lin g w ith in the
old w a lls of the gam etangium (F ig . 16), at le a s t in cu ltu ra l g erm lin g s .
N atural g e rm lin g s a r e not u su a lly con fin ed in the o ld gam etan g ia l w a lls
b eca u se th e se have d eca y ed aw ay from the zy g o sp o re p r io r to it s g e r m i
nation. H ow ever, th ere i s u su a lly a tig h tly packed m a ss of so il p a r t ic le s
surrounding the z y g o sp o re s of the n atural g erm lin g s and th e se p a r t ic le s
m ay act in th e sa m e m anner a s the gam etan g ia l w a ll in o b stru ctin g the
ea r ly grow th of the g e rm lin g s (F ig s . 1 9 “22).
F ig u r e s 1 1 -15 show the even ts w hich o ccu rred in the sam e
cu ltu ra l g erm lin g during a p er io d of four d ays. Two su b sequ en t o b s e r
v a tio n s, one at the end of sev e n days and the other at the end of two
w eek s r e v e a le d only the slow d eath .of th is g e rm lin g . The c a u se of death
i s unknown. T h ere w as an accu m u lation of b a c ter ia a long the c e l l w a lls ,
a s can be see n in the photographs, and th e se b a c ter ia p lu s in jury due
to m an ip u lation s m ay have been contribu ting fa c to r s , at le a s t , in the
a r r e s te d grow th and su bseq u en t d e m ise of th is g e rm lin g . The even ts
of c h lo r o p la stic reo rg a n iza tio n w ere see n in a num ber of other g e r m
lin g s , h ow ever, w hich d eve lop ed in to f ila m en ts of m o r e than 1 0 0 c e l l s
and show ed no s ig n s of dying, up to the tim e of th eir being d isca rd ed .
40
A s has been poin ted out in a p r e v io u s sec tio n of th is m anu
scr ip t, the c h lo r o p la s ts , at the tim e, of g a m etic form ation , begin to
fragm en t (Figo 3} and rem a in in th is cond ition throughout the p r o c e s s of
"conjugation and into th e m atu re z y g o sp o re until it b eg in s to g erm in a te ,
. A t th is tim e the a g g reg a ted fra g m en ts of the c h lo r o p la s tic m a ter ia l
appear in the o n e -c e ile d g erm lin g as m a s s e s of v a r io u s sh apes and
sizeso T h ese m a s s e s m ay or m ay not co m p le te ly f i l l the c e l l (FigSo
12, 1 6 ).o B ro w n ish -o ra n g e or r e d .ncaroten o id 11 g ra n u les a r e often seen
w ith in the s in g le -c e l le d g erm lin g (Figo- 12jo R em ark s about the p o s s ib le
or ig in of th e se g ra n u les w ill be found in the d is c u s s io n sec tio n of th is
m anuscripto T h ere i s a continuous s ta te of a c tiv ity w ith in the p ro to
p la s t A fter a p er io d of 30 m in u tes or m or e, rea rra n g em en ts! in the
c h lo r o p la stic fra g m en ts and the car otenoid g ra n u les b eco m e a p p a re n t
A s the c e l l e lo n g a te s , the c h lo r o p la s tic m a te r ia l b e c o m e s unequally
d istr ib u ted w ith in the ce ll; the la rg er am ount is found tow ard the a p ica l
end of the c e l t The b asa l c e l l d iv id es unequally in the reg io n of the
accu m u lation of the ch lo r o p la s tic m a te r ia l to g iv e r i s e to the secon d
c e ll of the f i la m e n t At about th is tim e one to s e v e r a l ir r e g u la r ly
shaped, r ib b on lik e s tr u c tu r es can be seen extending from both s id e s of
a m a ss of c h lo r o p la s tic m a ter ia L T h ese s tru c tu res r e p r e se n t the
beginning of the reo rg a n iza tio n of the c h lo r o p la s ts in the g erm lin g of
Sirogonium m elan osp oru m (com p are FigSo 11,. 12 w ith Figo 13)o
41
The carotenoid g ra n u les can be see n in the a p ica l c e l l of the
tw o -c e lle d germ ling in F ig u r e 13= T h ese gran u les a r e not a lw ays
tr a n s fe r r e d to the a p ica l c e l l a s a d is c r e te m a ss a s th ey have been in
th is germ ling but th ey m ay be ran d om ly d istr ib u ted in to the c e l ls of the
young fila m en t and even tu a lly lo s t from v ie w . The r ib b on lik e s tr u c tu r es
b eco m e m o re p rom in en t a s can be see n in F ig u re 14. . In fact, the
seco n d c e l l of th is fo u r -c e lle d germ ling has it s ch lor op la s t s su ffic ie n tly
reo r g a n iz e d to be r e c o g n iz e d as a c e l l in a .fila m en t o f Sirogonium u
The b a sa l and a p ica l c e l l s of the fo u r -c e lle d germ lin g show the le a s t
reo rg a n iza tio n of the c h lo r o p la s ts and the a p ica l c e l l w ill rem a in th is
w ay even after the g erm lin g i s m any c e l l s longo . F ig u r e 15 show s the
sa m e g e r m lin g £s d evelop m en t four days a fter the o n e -c e lle d stage*
The b a sa l, secon d , and th ird c e l l s o f th is s ix - c e l le d g erm lin g have
r e la t iv e ly w e ll d eve lop ed ch lor o p la s ts w h erea s the fourth and fifth c e l l s
a r e s t i l l in the p r o c e s s of reorgan ization * The c h lo r o p la s ts of the
a p ica l c e l l , a s has been m en tion ed e a r lie r , do not b eco m e o rg a n ized
for -some time*
G erm lin g s of 5 0 -1 0 0 c e l l s in length , i f they happen to bend
su ffic ie n t ly for one p ortion of the f ila m en t to co m e in to con tact w ith
another, w ill conjugate* C onjugation in th e young g e rm lin g s w as ob
ser v e d only in th o se d er iv ed from cu ltu re and it i s not known w hether
g erm lin g s from the M ex 22 s o il w ill conju gate at th is v e r y ea r ly s ta g e
of developm ent*. The natural g e rm lin g s have never bent su ffic ien tly
42
for one p ortion of the fila m en t to com e in to con tact w ith another and
th is m ay fu lly accou nt for the lack of conju gation .
. F ig u re 21 show s a fo u r -c e lle d germ ling from a natural z y g o
sp o re in about the sam e sta g e of d evelop m ent and of c h lo r o p la s tic
reo rg a n iza tio n a s the fo u r -c e lle d cu ltu ra l germ ling in F ig u re 14. The
h e m isp h er ic a l bu lge betw een the b a sa l and seco n d c e l l of the fila m en t
w as the r e s u lt of in ju ry during th e rem o v a l of d irt adh ering to the
g erm lin g . A nother fo u r -c e lle d natural g erm lin g w h ich con ta in s r e o r
gan izin g c h lo r o p la s ts and m any o il d ro p le ts i s shown in F ig u re 20.
O nce the c h lo r o p la s ts of a c e l l of a g erm lin g have organ ized ,
any c e l l s r e su lt in g from d iv is io n of th is c e l l w ill a lso have o rgan ized
c h lo ro p la sts b eca u se of the nature of c e l l d iv is io n d e sc r ib e d on page 29
of th is m a n u scr ip t. , The c h lo r o p la s ts in the ap ica l c e l l do not fu lly
r eo rg a n ized until the g erm lin g i s 1 5 -2 0 c e l l s long or lo n g e r . In the 2 0 -
ce lled , natural g erm lin g of F ig u r e s 22, 23, 24 can be see n the p r o g r e s
s iv e u n sp ira llin g , narrow ing , and lengthenShg of the c h lo r o p la s ts from
the som ew h at u n organ ized c h lo r o p la s tic m a te r ia l of th e a p ica l c e l l to
the h igh ly o rg a n ized and stra ig h t c h lo r o p la s ts of th e sec o n d c e l l . T his
p r o g r e ss io n i s il lu s tr a te d even b etter in the four en la rg em en ts of s e c
tion s of the p reced in g g erm lin g (F ig s . 25,. 26, 27, 28).
T h ese f ig u r e s a lso i l lu s tr a te the v a ry in g num ber of c h lo r o p la s ts
a s so c ia te d w ith the d ifferen t c e l l s of the fila m en t at th is sta g e of th e
g e r m lin g £s d evelop m en t. The b a sa l c e l l m ay have from I to 4
43
chL oroplasts but u su a lly no m o re than 2 of them exten d in to the b asa l
I / 3 - 2 / 3 of the c e lh The seco n d c e l l m ay have from 3 to 6 c h lo r o p la sts
and the th ird c e l l from 4 to 7. . C e lls beyond the th ird one m ay have up
to 9 ch lorop lasts* T h ere a r e u su a lly few er c h lo r o p la s ts , 5 to 8 , in
c e l l s tow ard the ap ex of the filam ent* S in ce m o st of th e s e c e l l s w ill
in c r e a s e the num ber of th eir c h lo r o p la s ts up to 7, 8 , or 9, th ere m u st
be a m ethod of du p lication of the c h lo r o p la s ts w hich w as not o b serv ed
by the author * It i s not unusual to fin d sh ort p ie c e s of c h lo r o p la sts
w hich extend only a p ortion of the w ay from one end of the c e l l to the
other and it i s p o s s ib le that th ese sh o rt p ie c e s grow in length to
b ecom e th e f u l l - s iz e d c h lo r o p la s ts of the v e g e ta tiv e c e lls* , W here th e s e
p ie c e s co m e from i s not k n o w n ,. how ever*
Two d iffe re n c e s w ere noted betw een the grow th and d ev e lo p
m ent of natural v e r s u s cu ltu ra l g erm lin gs* F ir s t , r eo rg a n iza tio n of
the c h lo r o p la s tic fra g m en ts in to c h lo r o p la s ts w as u su a lly s lo w er in
cu ltu ra l g e r m lin g s , and secon d , th ey did not u su a lly h ave the v e r y
e lon gate and ta p ered b a sa l c e l l found in m o st of the n atural germ lin gs*
A s has been m en tion ed p r e v io u s ly , th e se a re only te n d en c ie s and not
a b so lu te d ifferen ces*
In T able 8 a r e found the c e l l len g th s, the a v e ra g e c e l l len gth s
in clu d in g .an d not inclu d ing the b a sa l c e l l , and th e g r e a te s t w idth of the
fila m en ts during s u c c e s s iv e s ta g e s of grow th of the cu ltu ra l germ ling
p ic tu red in F ig u r e s 1 1 -1 5* In T able 9 a re found the sa m e data for the
44
natural germ Ling, shown in F ig u r e s 2 2 -2 8 , ex cep t that so m e of th e c e l l
length S3 h ave been d e le ted in ord er to red u ce the ta b le to a m an ageab le
size* The b a sa l c e l l in e ith er g erm lin g i s co n s id era b ly longer than
any other c e l l in th e fila m en t and th e se c e l l s continued to e longate
throughout the p er io d of ob serv a tio n of the two germ lings* A fin a l
ob serv a tio n of the natural g erm lin g of T able 9 w as m ade 336 hr (14
days) a fter the f ir s t observation* The fila m en t of th is g erm lin g w as
co m p o sed of 72 c e l l s and m e a su r ed 14, 986 m ic r o n s in to ta l length*
The r e su lt in g .a v e r a g e of 208 m icro n s p er c e ll , includ ing the basa l
c e ll , i s su b sta n tia lly g rea ter than the 167 m icro n s per c e l l of the 51 -
ce lled , 208 hr ( 8 2 /3 days), s ta g e of grow th of the germ ling*
It w ill be noted that the b a sa l c e l l of the natural g erm lin g ( s e e
T able 9). d iv ided betw een the 1 0 - and 1 9 -c e l le d s ta g e s of grow th. The
sh orter c e l l s r e p r e se n t prod u cts of r e c e n t c e l l d iv is io n and a num ber
of them w e r e see n b efo re the septum w as co m p leted (Fig* 10)* The
p ro x im ity of n u c le i to the septum or tr a n s v e r s e w a ll i s an in d ica tion ofs
a s lig h tly la ter s ta g e in r e c e n t c e l l division* The n u cle i m ig ra te to
the cen ter of the c y lin d r ic a l c e l l s sh o r tly a fter c e l l d iv is io n i s co m p le ted .
45
T able 8 * . C ell len gth s,, a v era g e c e l l len g th s, and g r e a te s t w idths at s u c c e s s iv e s ta g e s o f grow th of a cu ltu ra l germ ling of Sirogonium m ela n o sp o ru m 0 A ll m e a su r em e n ts a r e g iven in m ic r o n s .
Hr from 1 st o b serv a tio n 0 c a . 24 c a . 48 ca .. 9 6
Length of fila m en t 1 - c e l le d 2 - c e l l ed 4 - c e l le d 6 - c e l le d
B a sa l c e l l (1st). 205 340 355 375
2 nd 170 105 135
3rd 40 2 0 0
4th 170 85
5 th 75
6 th 195
A vg. length of c e l l s w ithout b a sa l c e l l
— 170 105 136
A vg. length of a ll c e l l s of the fila m en t
205 255 167 178
T otal length of fila m en t 205 510 670 I , 065
G rea test w idth of fila m en t 73. 7 78. 0
o00 .
l> o00
l>
46
T able 9s. S e le c ted c e l l len g th s, a v era g e c e l l lengths in clu d in g a ll d e le ted c e l l len g th s, and g r e a te s t w idths at s u c c e s s iv e s ta g e s of grow th of a natural germ ling of S irogonium m e la n o - sporutrio A ll m e a su r em e n ts a r e in m icronso
6 -c e l le d 1 0 -c e l le d 1 9 - c e l le d 2 4 -c e lle d 2 8 -c e lle d 41 -c e l le d 51 - c e l le d0 hr 2 0 hr 44 hr 77 hr 1 0 1 hr 150 hr 208 hr
I Stc e l l 536 670 597 . 876 999 1 , 128 I , 2052 nd 1 2 6 154 2 1 6 371 402 340 5663rd 6 8 103 170 ■ 258 309 340 3354th 76 93 154 252 2 6 8 309 3195th 119 103 103 185 124 206 2476 th 156 103 >98 165 ' 113 137 1479 th 6 2 82 82 139 175 1031 0 th 103 82 72 98 154 11318th 6 2 103 103 154 10319th 113 103 108 124 11323rd 93 72 144 8224th 124 6 2 1 6 0 10327th 52 98 18528 th 93 93 10340 th 77 1544 1 st 93 15442nd 144 15450th 11351 st. 154A vg. length of c e l l s exclu din g b asa l c e l l
109 95 94 133 1 2 6 ■ 142 152
Avgfo length of a ll c e l l s of th e fila m en t180 152 120 164 158 166 167
Total length of the fila m en t1, 082 1 , 524 2, 281 3, 929 . 4, 411 6 , 973 8 , 523
i
G rea test w idth of th e fila m en t7 7 .2 76. 6 7 6 .2 - - 7 7 .3 7 7 . 3
F ig u r e s 3-5o - Sirogouiuiri rnelanosporum from cu ltu re .
F ig u re 3. G am etan gia l fo rm a tio n . N ote the fra g m en ted nature of th e c h lo r o p la s ts in both gam etan g ia . _ F e m a le gam etangium (a). M ale gam etangium (b).
F ig u re 4 . G a m etes . N ote the co n cen tra ted nature of the c h lo ro p ia stic m a te r ia l in the g a m e te s . The double conjugation shown i s not com m on in S. m e la n o sp o ru m . . "'Female gam etangium (a) contain ing the la r g e fe m a le g a m ete . M ale gam etangium (b) contain ing the sm a ll m a le g a m ete w h ich w ill m o v e through the p ore (c) to un ite w ith the fe m a le g a m ete .
F ig u re 5. A zy g o te 30 m in . a fter the fu sio n of the g a m e te s . N ote theco n cen tra ted nature of the ch lor o p ia stic m a te r ia l in the zy g o te .
, A lso note the conjugation tube. F e m a le gam etangium (a) contain ing the young zy g o te . The em pty m a le gam etangium
(b)o
\
47
Rg. 3
Fig. 4
Fig. 5
F i g u r e s 6-7o S iro g o u iu m m e ia n o sp o r u tn fr o m c u l t u r e 0
F ig u re 6 0 . A young zy g o sp o re contain ing g reen ch io r o p ia s tic fr a g m e n ts 0
F ig u re 7, . A m atu re z y g o sp o r e 0 N ote the brown co lo r and v e r r u c o s e nature of the m edian sp o re w alL The tra n slu cen t outer sp o re w a ll i s a ls o v is ib ie 0
F ig u r e s 8-9° • S irogonium xaelanosporiiim from culture,.
F ig u re 8» . A sm a sh ed zy g o sp o re show ing the tran sp aren t inn er c e l lw a ll w ith in the outer w a lls . N ote the ornam entation of the hr own m ed ian sp o re w a ll.
. F ig u r e 9» . A m atu re zy g o sp o re w h ich w as sm a sh ed in IKL N ote thecop iou s s ta rch g ra n u les w hich appear brown to b lack in th is i l lu s tr a t io n .
F ig u re 10 .. S irogonium m elan o sp o ru m , from M ex 22 so il show ing a c e l l in the p r o c e s s of d iv is io n . N ote how the p a r tia lly d evelop ed septum h as c o n s tr ic te d the c h lo r o p la s ts .
Ffg.8
Fig>9
Ffg.10
/
. F ig u r e s 11 - I5« , S irogonium m elan osp oru m from cu ltu re . T his s e r ie sof photographs r e c o r d s four s u c c e s s iv e s ta g e s of grow th in a s in g le germ lin g . C arotenoid g ra n u les (a).
„ F ig u r e s 1 3 -1 5 . The sh ort b lack lin e s ou tsid e the f ila m en ts in d ica te the p o s it io n s of the c e l l w a lls ; the b a sa l or f ir s t c e l l i s to the le ft .
F ig u re 11. O n e -c e lle d g erm lin g . N ote the fra g m en ted nature of the c h lo r o p la s tic m a te r ia l.
F ig u re 12. Sam e v iew a s F ig u r e 11. N ote the fra g m en ted nature of the c h lo r o p la s tic m a te r ia l.
F ig u re 13. . T w o^ celled s ta g e . , P hotograph taken about 24 hr a fter •' F ig u r e s 11, 12. N ote the d iso rg a n iza tio n of the c h lo r o
p la s t ic fr a g m e n ts .
F ig u re 14. F o u r -c e lle d s ta g e . . P hotograph taken about 48 hr a fterF ig u r e s 11, 12. N ote the beginning of o rg a n ized c h lo r o - p la s ts in the seco n d c e l l .
. F ig u re 1 5 .. S ix -c e l le d s ta g e . Photograph taken about 96 hr afterF ig u r e s 11, 12. N ote the r e la t iv e ly w e ll d evelop ed c h lo r o - p la s ts in th e seco n d and th ird c e l l s .
F ig u r e s 1 6 -1 8 . . S irogonium m elau osp oru m from cu ltu re .
F ig u re 16. O n e -c e lle d germ lin g w ith in fe m a le gam etan g iu m .
F ig u re 17. T h r e e -c e l le d germ lin g . N ote the d iso rg a n ized c h lo r o - p la s t ic m a te r ia l.
F ig u re 18. B a sa l p ortion of s e v e n - or e ig h t -c e l le d g e rm lin g . N ote the l in e of d e h isc en ce in the zy g o sp o re w a lls .
51
Fig. 16
1 0 0 /<
Fig.17
Fig.18
F ig u r e s 19-21« S irogoniu iu m elauosporurn. from M ex 22 so iL F ig u r es 19 9 21 o.. The b u lges betw een the b a sa l and secon d c e ll (a r r o w s),w e r e the r e s u lt of in jury during c lean in g of the f i la m e n ts »
F ig u re 19o Four - c e l le d natural germ lingo N ote the bend in the fila m en t and the long ta p ered b a sa l c e l l extending out from the z y g o sp o re c a s e .
F ig u re 20. F o u r -c e lle d natural germ lin g . N ote the d iso r g a n iz e d c h lo r o p la s tic m a te r ia l.
F ig u re 21=,.. F o u r -c e lle d natural germ lin g . N ote the f in g e r - l ik echi or o p la sts extending out from a d en se , c en tr a l m a ss of ch lo r o p la s tic m a te r ia l.
r 52
100/
Fig.19
100 /
Fig. 21
F ig u r e s 2 2 -2 4 , S irogouium .m elanosporurn frorn M ex 22 s o il , A s in g le , 2 0 -c e l le d natural g erm lin g . N ote the v e r y long b asa l c e l l . A s the c e l l s e lon gate , from the a p ic a l tow ard the b a sa l end, the c h lo r o p la s ts u n sp ira l and elon gate a ls o .
F ig u r e 22, F rom le ft to r igh t, zy g o sp o re c a se , b asa l and seco n d c e l l s , and part of the th ird c e l l . N ote the long, s tra ig h t, r ib b on lik e c h lo r o p la s ts .
F ig u re 23, - P a rt of the th ird c e l l , and fourth through eighth c e l l s . N ote the change from stra ig h t to sp ir a lle d c h lo r o p la s ts in the fourth and fifth c e l l s r e s p e c t iv e ly .
F ig u re 24, N inth through a p ica l (tw entieth).,-cells. N ote that the ch lp r o - p la s ts a r e m o re tig h tly sp ir a lle d . The a p ica l c e l l has the le a s t w e ll r eo r g a n iz e d c h lo r o p la s ts . M any of th e c e l l s have a co n sp icu o u s n u c leu s .
e s - B y
. F ig u r e s 2 5 -2 8 , . P o r tio n s of the sa m e n atu ra l g erm lin g of F ig u r e s 2 2 -2 4 ,
F ig u re 25, . F ou rth c e l l . N ote the fla t, stra ig h t c h lo r o p la s ts contain ing p y ren o id s .
F ig u re 26, F ifth c e l l . N ote the sp ir a lle d c h lo r o p la s ts and the n u cleu s su sp en d ed in the cen ter of the c e l l .
F ig u re 27, E ighth and p art of the ninth c e l l s . N ote the c lo s e ly sp a ced and h igh ly s p ir a lle d c h lo r o p la s ts w ith w avy m a r g in s .
F ig u re 28, , The a p ica l (tw entieth ) c e l l . N ote the p a r tia l d iso rg a n iza tio n of the c h lo r o p la s ts .
LZ ‘By
DISCUSSION
Sirogonium m elanosporurn has been found in th ree quite d if fe r
ent habitatso A t G r ee n v ille , M is s is s ip p i even the d r ie s t m onth,
O ctober, a v e ra g e s over two in ch es of r a in fa ll and the annual a v era g e
i s g r ea ter than 50 in ch es (T ab le 6 )« . In Uttar P rad esh ,. India the d r ie s t
m onth has le s s than o n e -h a lf of one in ch of ra in fa ll and th ere i s an
extended p er io d from O ctober through May. in w hich th e m onthly, aver -
age i s about one in ch or l e s s . The su m m er m onsoon b rin gs the g rea ter
p art of the y e a r ly a v era g e of over 35 in c h e s (T able 5). The G uaym as,
M exico s ite i s s im ila r to the Indian s ite in at le a s t one r e sp e c t; the
g r ea ter p art of the ra in fa ll c o m e s during the su m m er sea so n , but
G uaym as r e c e iv e s on ly o n e -f ifth as m uch ra in during th is sea so n as
d oes Uttar Pradesho , At G uaym as th ere a r e long p er io d s of l i t t le or no
ra in fa ll, and the m onth of June has so l i t t le that it a v e r a g e s l e s s than
0o 05 of an in ch . The f ir s t habitat i s m o is t a ll year long but it i s w e tte s t
in w inter and e a r ly sp rin g , N ovem ber through A p rih . The seco n d is
v e ry w et during the su m m er m onsoon , June through S ep tem b er, w ith a
m uch drier p er io d from O ctober through M ay. The la s t s ite i s quite dry
w ith only sp orad ic su m m er r a in s , from July through Sep tem b er and long
p e r io d s of drought from O ctober through June. The two c lo n es of
Sirogonium m e la n o sp o f um u sed in th is study have, at le a s t , four
55
56
a ttr ib u tes w hich w ould m ak e them "fit" for th e ir en v iron m en t at G uay-
m aso F ir s t , th is a lga grow s w e ll at tem p era tu res of 25 C and above.
T em p era tu res of th is m agnitude do p r e v a il during the su m m er grow ing
sea so n at G uaym as (T ab le 3), Second, th is a lga can p rod u ce m atu re
zy g o sp o re s in the r e la t iv e ly sh o rt p er io d s of a v a ila b le m o is tu r e . In
fa c t, the p r o c e s s of grow th from z y g o sp o re germ in ation to the p ro d u c
tion of m atu re zy g o sp o re s m ay take only 2 -3 w e e k s . T hird , a r e s is ta n t
zy g o sp o re i s prod u ced w hich r e m a in s v ia b le throughout the long p er io d s
of drought, . Fourth,, zy g o sp o re s exh ib it d ifferen tia l germ in ation , i , e ,
th ey do not a ll g erm in a te during a s in g le w ettin g . T h is type of g e r m in a
tion i s advantageous in a llow in g th is a lg a to p e r s is t in th e h a rsh e n v ir o n
m ent near G uaym as, F o r exam p le , if a ll z y g o sp o re s g erm in a ted during
an e a r ly ra in and th e pond d ried up again b efore m atu re z y g o sp o res
could be produ ced then th is a lga w ould p e r ish from th is s i t e , , If a study
cou ld be m ade of the s im ila r it ie s and d if fe re n c e s of c u ltu re s of
Sirogonium m elan osp oru m from the th ree d ifferen t s i t e s , a better id ea
of the con cep t of a s p e c ie s in th is genus m igh t be ga in ed , . U nfortunately
cu ltu res from M is s is s ip p i and India h ave not been obtainab le up to the
p r e se n t t im e .
C ell d iv is io n , in th e two c lo n e s of S irogonium w hich w ere
stud ied , i s qu ite siraila-r to c e l l d iv is io n in the genus S p irogyra as
rep o rted by A llen (1958), . C y to k in esis exten ds over m o r e than an hour
in both g en era and it i s a cco m p lish ed by the annular ingrow th of a
57
septum w hich f in a lly cu ts the c h lo r o p la s ts in tw o 0 W hether the a c c o m
panying, p r o c e s s of k a r y o k in es is i s s im ila r in th e two g en era is not
known as it i s la r g e ly o b scu red by th e c h lo r o p la s ts of the liv in g m a te
r ia l , The n u c le i a re v is ib le only a fter cy to k in es is i s co m p le te .
The s iz e and shape of z y g o sp o re s i s h igh ly v a r ia b le in the
clon a l cu ltu res and th ere i s so m e v a r ia tio n in th o se from the natural
M ex 22 so il sa m p le a ls o . One p o s s ib le explanation for th is v a r ia b ility
i s that optim um growing, con d ition s m ay not a lw ays p r e v a il from one
a rea to another in a pond or from one b o ttle to another in the lab oratory
c u ltu r e s , • E n v iron m en ta l con d ition s m ay a lso change w ith tim e in e ith er
la b ora tory c u ltu re s or a pond as n u tr ien ts a r e a s s im ila te d from and
w a ste s a re e x c r e te d into the m ed iu m . A nother exp lanation i s in h eren t
v a r ia b ility w ithin, th is s p e c ie s . In a c tu a lity both of th e se fa c to r s p ro b
ab ly in te r a c t , The p o s s ib il ity of b a c ter ia and fungi in ter fe r in g w ith the
grow th of the c u ltu re s should not be o verlook ed .
The v e r y low p ercen ta g e of g erm in a tio n of z y g o sp o r e s from
cu ltu re i s s t i l l u n reso lv ed , . W hether th is low p ercen ta g e of g e r m in a
tion o ccu rred in natural z y g o sp o re s cou ld not be a sc e r ta in e d b eca u se
no sa tis fa c to r y m ethod of counting the num ber of z y g o sp o r e s in a m e a s
ured am ount of the M ex 22 so il w as d e v ised , A low p e r ce n ta g e of
g erm in a tio n w as a lso obtained in the gen u s S p irogyra by A llen (1958),
An explanation m ay in v o lv e a g en etic co n tro l m ech a n ism lead ing to
d ifferen tia l germ in ation w hich , a s h as been sta ted e lse w h e r e , m ay
58
confer an advantage on an a lga liv in g in r eg io n s of lim ite d and h igh ly
er r a tic ra in fa lLI '
By far the m o st co m p le te accou nt of the v e g e ta tiv e and sex u a l
p h a ses of th e genus S irogonium i s g iven by D e B ary (1 858} but h is
accou nt i s b a sed e n tir e ly on S irogonium stic ticu m w hich d iffers s o m e
what from So m elan osp oru m , e sp e c ia lly in the ev en ts p reced in g the
form ation of the g a m e te s . Both s p e c ie s begin the conjugation p r o c e s s
by the jo in ing to g e th er of two c e l l s w h ich a re s lig h tly bent tow ard one
anoth er. In S. m elan osp oru m th ere i s often produ ced a ra th er pronounced
conjugation tube w h ile in S. s tic ticu m th is tube i s r e p r e se n te d m e r e ly by
slig h t b u lg es . A lthough unequal c e l l d iv is io n g iv e s r i s e to the gam etan g ia l
c e l l s i,n both species^ th e .s m a ll c e l l i s m uch sm a lle r and r em a in s sm a ll
in S. s tic ticu m (the " ste r ile" c e l l of De B ary, 1858) w h erea s it ap p ears
to e lon gate in S. m elan osp oru m and in m o st c a s e s look s v e r y m uch lik e
an ord in ary v e g e ta tiv e c e l l . . In both: s p e c ie s the fe m a le gam etangium
b eco m es g rea tly in fla ted but the m a le gam etangium in f la te s only s lig h tly
or not at a ll . At the sa m e tim e the c h lo r o p la s ts b eco m e sh o rter , w id er ,
and appear to b eco m e lin ked one w ith the other by sh o rt p r o je c tio n s .
In S. m elan osp oru m th e se apparent lin k s a re fo rm ed a s the ch lo r o p la s ts
fragm en t and the p ie c e s b ecom e rea rra n g ed ( s e e F ig . 3). The r eg io n s
around the p y ren o id s b ecom e m o re and m o re d istin c t a s s ta rch g ra n
u le s a ccu m u la te . O il d rop lets a re a lso fo rm ed . The n u cleu s b eco m es
e n tir e ly ob scu red . The g a m etes round up b efo re fu sio n o c c u r s . In
59
both s p e c ie s a th r e e - la y e r e d w a ll i s fo rm ed around th e zy g o te but the
c o lo re d m edian w a ll i s sm ooth in So s tic ticu m and v e r r u c o s e in So
m elanosporum o . Both s p e c ie s a r e h o m oth a llic and conju gation tak es
p la ce in the v a r io u s p a r ts of the fila m en t at v e r y d ifferen t t im e s so
that one m ay fin d the e a r l ie s t s ta g e s of conjugation v e r y near m atu re
zygosp oreso
. 13e B ary (1858) gave the fo llow in g accou nt of g a m etic fo r m a -
tion s g erm in a tio n of the zygosp or ea and e a r ly d evelop m en t of the g e r m -
ling in S» stic ticu m (from a tra n s la tio n by F ra u U se H e lle re r ):
Hov?ever, in both, (gam etan g ia ) th e con ten ts gradu ally change th eir c o n s is te n c y . The chi or o p ia sts b eco m e w id er , freq u en tly lin ked by A n astom osen ; «... . «. The in n er c e l l w hich len gth en s into th e form of a tube b rea k s through the en c lo sin g sk in s in a deep v e r t ic le t e a r „ One end r em a in s stuck betw een th e se sk ins; the other w ith i t s f irm w a ll p ro tru d es ca rry in g w ith it the ch lorop h y ll content broken up into ir r e g u la r sh red s w h ich s lo w ly s tr e tc h out in to g reen fils/m en ts. The num erous o il g lo b u les a ttach ed to the ch lo ro p h y ll d isap p ear grad u ally .The l it t le heap s of r e d p igm en t rem a in d is tin c t long after the event of p a rtitio n . . I have not o b se r v e d any n u cleu s in o n e - c e lle d g e r m lin g s . Just a s w ith S p irogyra , h ow ever, a n u cleu s is a lw ays p r e se n t a fter the f i r s t d iv is io n .
. It i s in ter e st in g , to note that De B ary im p lie d at two p o in ts in h is accou n t
of the l ife c y c le of S irogonium stic ticu m that the c h ld ro p ia sts do not
rem a in a s d is tin c t e n t it ie s . F ir s t ,, he sta ted that the ch i or o p ia sts
b ecam e "linked by A n astom osen " during ga m etic fo rm a tio n and secon d ,
that the "ch loroph yll content" i s "bsoken up into ir r e g u la r sh red s"
w hich s tr e tc h out to form the c h lo r o p ia s ts during the grow th of the
g e rm lin g . H ow ever, as w a s m en tion ed in the in trod u ction (p,, II);
60
De B ary (1858) p ic tu red a o n e -c e l le d g erm lin g w ith fu lly d evelop ed
ch lo ro p la stso
, The "Little h eap s of r ed p igm ent" m ay be co m p a ra b le to the
"red-brow n bod ies" in S p iro g y ra d e sc r ib e d in 1852 by No. P r in g sh e im
(A llen , 1 9 5 8 ) 0 T ron d le (1907) c a lle d th e " red -b row n b od ies" of S p iro
gyra " K arotin k rista llen " from w hich the cu rren t nam e of ca ro ten o id
gran u les i s d er iv ed . T h a t.th ese b o d ies , in th e genus S p irogyra , a re
the r em a in s of the d is in teg ra ted m a le ch lo ro p la stid w as f ir s t d em on
s tr a ted by V® C h m ielev sk y in 1890 acco rd in g to F r its c h (1935)® A lle n
(1958) sta ted that the fe m a le p la s tid r em a in s a s a c o m p r e ss e d green
band® "The m a le p la stid , on the other hand, soon Loses i t s c o lo r ,
b eco m es gran u lar, and ev en tu a lly fra g m en ts into a few groups of
orange ‘c a ro ten o id 8 granules.® " T his p r o c e s s o ccu rs in the zygospore®
L ew is (1925) d e scr ib e d the fo llow in g p r o c e s s : "The m a le gamete® ® ®
does not in c r e a s e notably in d ia m eter , a s d oes the fe m a le g a m ete , and
i s fu rth er d is tin g u ish ed by the fa c t that the c h lo r o p la st d is in te g r a te s
co m p le te ly , lo s in g both co lo r and form® " D is in teg ra tio n of the m a le
p la s tid o c cu rs during g a m e to g e n e s is in th is species of S p iro g y ra a c c o r d
ing to Lewis® T ron d le (1907) had the fo llow in g to say about a s p e c ie s
of S p iro g y ra w hich con ta in ed th ree c h lo r o p la s ts per c e l l in the v e g e ta
t iv e p h a se (from a tra n s la tio n by F ra u U se H e llerer ):
Quite young zy g o te s con ta in ed s ix d is tin c t bands w hich Looked fu lly lik e th o se of the v e g e ta tiv e cells® The ed ge is n o rm a lly sca llo p ed , the p y ren o id s conta in cop iou s sta rch , and
61
the co lo r i s a beautifu l g reen . A fter so m e fo u rteen d a y s. » .. th ere i s a change. The fin e ind en tation of the ch lo r o p la s ts d isa p p ea rs , and the c h lo r o p la s ts th e m se lv e s b eco m e m o re or l e s s w o r m -lik e , sh o r ter , but th ick er . . . .. Not only the form , h ow ever, but a lso the co lor ch a n ges, at le a s t in p a r t. T hree c h lo r o p la s ts rem a in g reen , w h erea s the th ree o th ers b ecom e r e d d ish -y e llo w , s im ila r to a le a f som ew h at autum n -faded .The c h lo r o p la s ts of lik e c o lo r s each form a group, and, ind eed , th e one i s m a le , the other fe m a le . In a ll c a s e s , in fact, w h ere the conju gation can al w as c le a r ly v is ib le , for exam p le jo in ed la te r a lly to the c h lo ro p la st in p rep a ra tio n , I saw im m ed ia te ly opp osite it s opening, the th ree d is c o lo r e d ch lo ro p la sts ,- w h erea s the o th ers o ccu p ied the op p o site p o s i tion in the zygote; w hereupon I con clu ded that the f ir s t a re m a le , the la tter fe m a le . In s t i l l o ld er zy g o te s , the m a le bands d is in teg r a te in to s in g le p ie c e s w h ich form round to long m a s s e s , and under w eak pow er th e se appear d is tin c t ly gran u lar .O b servation under h igh pow er sh ow s'th a t n u m erou s l it t le y e llow c r y s ta ll in e -sh a p e d g ra n u les a re p r e se n t .
In S irogonium m elan d sp oru m , h ow ever, both the m a le and the fe m a le
c h lo r o p la stid s fragm en t during g a m e to g e n e s is and th ere i s no apparent
d is in teg ra tio n or d isc o lo r a tio n of p ia s t id fra g m en ts up to the tim e of
e a r ly zy g o sp o re form a tio n . The car c ten o id gra n u les in S. m e la n o -
sporum m igh t s t i l l be d er iv ed from the d is in teg r a te d fra g m en ts of the
c h lo r o p la s ts from e ith er the m a le or the fe m a le g a m ete or p ortion s of
both, but i f so , the d is in teg ra tio n o c cu rs a fter the o b scu rin g food
r e s e r v e s and z y g o sp o re w a ll have fo rm ed . The author h as no c o r r o b o r a
tiv e ev id en ce that the or ang e -r br own g ra n u les seen in m o st germ lin g s of
the Sir ogonium m elan o sporum cu ltu res a r e the r em a in s of c h lo r o p la sts
from e ith er the m a le or the fe m a le g a m e te s . The g ra n u les even tu a lly
b ecom e d isp e r se d by c e l l d iv is io n in th e germ lin g s and a r e no longer
v is ib le a fter 2 -1 0 m ito s e s . They a r e v is ib le , h ow ever, a s a d is c r e te
62
group in the a p ica l c e l l of the v a r io u s s ta g e s of grow th of the cu ltu ra l
germ ling shown in F ig u r e s 11, 12, 13, and 14. . In other germ lin g s ,
both natural and cu ltu ra l, th e se g ra n u les m ay be c o m p le te ly d isp e r se d
and not d is c e r n ib le from the other c e l l con ten ts in the 2 - , 3 or 4 -
c e lle d s ta g e s of grow th (F ig s .. 16, 19, 20).
, It i s p o s s ib le , though th is author has no ev id en ce for it, that
th ese gra n u les r e p r e se n t d is in teg ra tio n p rod u cts of n u clear m a ter ia l
produced during m e io s is in the zy g o te of S irogonium m elah osp oru m , if,
indeed , m e io s is o ccu rs h ere a s it does in s e v e r a l s p e c ie s of S p irogyra
(T ron d le , 1911; Godward, 1961). In any c a s e it i s c er ta in that m o re
w ork n eed s to be done in order to d e term in e the o r ig in and co m p o sitio n
of th e se o ra n g e-h r own g ra n u les in S irogon ium m elanosporum o
That c h lo r o p la s ts can fra g m en t and r e o r g a n iz e under a p p ro p r i
a te con d ition s, such as grow th in the dark, h as been d em o n stra ted in
the genus E uglen a by W olken (1956,. 1961). It d oes not, th er e fo re , see m
so im p rob ab le that other co n d ition s, such a s th o se a r is in g from g a m e to -
g e n e s is , m ight ind uce ch lor op la s t fra g m en ta tion a lso , a s app arently
o ccu rs in the c u ltu re s of So m elan osp oru m u sed in th is study. . R e o r
gan ization of the ch lor o p la sts of E u glen a o ccu rs w hen th is a lga is
retu rn ed to the ligh t. In S. m elan osp oru m the r e o r g a n iz a tio n of the
c h lo r o p la s ts o ccu rs w ith the g erm in ation of the z y g o sp o re and the e a r ly
grow th of the g erm lin g .
63
The o r ig in of p la s tid s a cco rd in g to W eier (1963), h as not y et
b een fu lly so lv ed ev en w ith e lec tr o n m ic r o sc o p y « A study of the u ltr a
stru ctu re of S irogonium m elan osp oru tn throughout the p r o c e s s of
ch lo r o p la s tic fra g m en ta tion and reo rg a n iza tio n ;m ig h t w e ll exten d the
p r e se n t know ledge con cern in g the o r ig in of p la s t id s .
It i s in ter e st in g to note that although c r o ss -c o n ju g a tio n does
v e r y r a r e ly o c c u r ,' in d ica tin g that it i s p o s s ib le for ad jacen t c e l l s on a
fila m en t to d ifferen tia te into m a le and fe m a le gam etan g ia , no la te r a l
conju gations w e r e ev er o b serv ed . The p rob lem of s e x d ifferen tia tio n
in S irogonium m elan osp oru m or in the w h ole genus,, for that m a tter ,
n eed s e x te n s iv e study.
SUMMARY
lo . S irogon ium m elan osp oru m (Randhawa) T ra n sea u h as been
found in a pond near G uaym as, Sonora, M exico,,
2» The sex u a l p r o c e s s , conjugation , o c cu rs r e g u la r ly w ith in
the c lo n a l cu ltu res; th is a lga i s , th er e fo re , hom othallico
3o The width of the m atu re f ila m e n ts v a r ie s from 70 to over
80 m ic r o n s in a few in s ta n c e s .
4„ The sh ap es and s iz e s of z y g o sp o re s a r e h igh ly v a r ia b le .
5 . C ultural zy g o sp o re s can be in d u ced to g erm in a te by drying
them at room tem p era tu re for s e v e r a l w eek s and then w ettin g them w ith
s o il-w a te r supernatan t. L e s s than 5% g erm in ation o c cu rs u sin g th is
m ethod but no other m eth od w as d e v ise d w hich w ould in c r e a s e th is low
g erm in a tio n .
6 . O ils and e sp e c ia lly s ta rch a r e a ccu m u la ted during ga m etic
form ation and th e s e food r e s e r v e s a r e abundant in the zy g o sp o re and
the young g erm iin g a s w e ll.
7. F ra g m en ta tion of the c h lo r o p la s t o ccu rs during the fo r m a
tion of both of the g a m e te s . The c h lo r o p la s ts r em a in a s fra g m en ts
throughout the p er io d of ga m etic fu sio n , zygo te m atu ration and d o r
m an cy , z y g o sp o re g erm in a tio n and into the e a r ly s ta g e s of d evelop m en t
of the g erm iin g .
64
65
8 o , R eo rg a n iza tio n of the c h lo r o p la s ts b eco m es apparent at
about the 2 - to 4 - c e l le d s ta g e of g erm lin g develop m en t,
9» The f ir s t s ta g e s in the reo rg a n iza tio n of the c h lo r o p la sts
a r e f in g e r - lik e p ro jec tio n s of c h lo r o p la s tic fra g m en ts extending from
both s id e s of a c en tr a lly lo c a te d m a ss of the sam e ch lor o p la stic m a te -
rialo A s reo rg a n iza tio n con tin u es the cen tra l m a ss d im in ish es in s iz e
and the r ib b on lik e c h lo r o p la s ts of th e m atu re c e l l of S irogonium a re
produ ced ,
10o . R eo rg a n iza tio n of th e c h lo r o p la s t i s quite s im ila r in both
the natural and the cu ltu ra l germ lin g s ,
11, The c h lo r o p la s ts a re re la tiv e ly , w ide w ith cren u la ted m a r
g in s and tightly, sp ir a lle d w hen they a r e f ir s t fo rm ed but a s the c e ll
e lo n g a tes the c h lo r o p la s ts un coil and appear to extend ,
12, . A grad ation from p o o r ly to h igh ly o rg a n ized c h lo r o p la sts
can be see n from the a p ica l tow ard th e b a sa l c e l l s , r e s p e c t iv e ly , in 1 0 -
to 5 0 -e e l le d g e rm lin g s ,
13, . O range-brow n gra n u les a r e p r e se n t in th e e a r ly s ta g e s of
the d evelop m en t of the g e rm lin g s in the two cu ltu res o f S irogonium u sed
in th is study. T hey m ay be co m p arab le to the " ca ro ten o id 11 gran u les
w hich in a few s p e c ie s of S p irogyra h ave b een shown to be the rem a in s
of the d is in teg r a te d m a le c h lo r o p la s ts ,
14, . C ell d iv is io n does o c c a s io n a lly occu r in the b a sa l c e l l of
Sirogon iu m ,
LITERATURE CITED
A lie n ,. Mo. Ao 19 5 8 0 The b io logy of a s p e c ie s co m p lex in S p iro g y ra 0
Pho Do D isse fta tio n o . Indiana U n iv ,, Bloom ington= 240 p„
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