Western Kentucky University TopSCHOLAR® Masters eses & Specialist Projects Graduate School 12-1975 Ultraviolet Radiation Effects On Rotifers Syed Asim Hussain Follow this and additional works at: hp://digitalcommons.wku.edu/theses Part of the Astrophysics and Astronomy Commons , and the Life Sciences Commons is esis is brought to you for free and open access by TopSCHOLAR®. It has been accepted for inclusion in Masters eses & Specialist Projects by an authorized administrator of TopSCHOLAR®. For more information, please contact [email protected]. Recommended Citation Hussain, Syed Asim, "Ultraviolet Radiation Effects On Rotifers" (1975). Masters eses & Specialist Projects. Paper 1697. hp://digitalcommons.wku.edu/theses/1697
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Western Kentucky UniversityTopSCHOLAR®
Masters Theses & Specialist Projects Graduate School
12-1975
Ultraviolet Radiation Effects On RotifersSyed Asim Hussain
Follow this and additional works at: http://digitalcommons.wku.edu/theses
Part of the Astrophysics and Astronomy Commons, and the Life Sciences Commons
This Thesis is brought to you for free and open access by TopSCHOLAR®. It has been accepted for inclusion in Masters Theses & Specialist Projects byan authorized administrator of TopSCHOLAR®. For more information, please contact [email protected].
Recommended CitationHussain, Syed Asim, "Ultraviolet Radiation Effects On Rotifers" (1975). Masters Theses & Specialist Projects. Paper 1697.http://digitalcommons.wku.edu/theses/1697
'" '" '" '" '" I I!I e i!J •• 12 '8 20 24 28 32 TIME (DAYS)
FIGURE 4. PEJONr SURVIVAL VERll5 TD£-N:ll1M1\LIZED "IO '!HE !l.I\:m Rr FOUR I1IYS OF Fa:
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25
very small plateau and an apparent exp:>nential decrease in the pen:ent
surviving, a far greater rate of decrease than for the other groups.
Figure 4 if' a plot of the percent surviving as a function of
age for the control and irradiated groups nonralized to the data at
four days of age." 'l'NO distinctly different kinds of cw:ves are
obtained. '!he first type is given by the data of the control and the
3-minute and S-minute irradiated groups. All these remain relatively
close together, possessing the sane quali tati ve shape and decreasing
with time. However, the cw:ves for 7-minute and 9-minute irradiated
groups are decreasing apparently exp:>nentially, possessing the sarre
shape, but far fran each other.
Table 6 presents the uv radiation exp:>sures 0, the squares
of the exposures 02, the times (Tl/2) required to reach a 50 per
cent survival of the initial nUlri:ler of unirradiated rotifers for
various exp:>sures. Figure 5 is a plot of the reciprocal of time
(1/1'1/2) needed to obtain a 50 pen:ent survival of the initial number
of the unirradiated rotifers as a function of exp:>sure o. Initially
the curve has a sooulder and afterwards increases with the increase
in exp:>sure. Figure 6 is a plot of the reciprocal of the time
(1/Tl / 2) required to get 50 percent survival of the rotifers versus
the square of the exp:>sure, 02 . The curve has a small sroulder and
then increases with the exp:>sure.
*The data was nonralized by considering the number of rotifers alive at four days of age as 100 pen:ent survival and then obtaining percent of surviving rotifers for different days of age.
26
Table 6
W EXPCSURES, THE SQ~ OF THE EXPCSURES l\ND THE TDES ~RED TO RFJ\OI 50 PEICENl' SURVIVAL
Figures 7, 8, and 9 depict the percent surviving versus e>cp:lsure
an the second, fourth, and eighteenth day of the experimmt. It is
clear fran Figures 7 and 8 that the curve decreases slowly with the
increase of e>cp:lsure whereas in Figure 9 the curve decreases sharply
with the increase of e>cp:lsure.
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OIAPTER IV
DISClESION
'Ihe data in Figure 3 srow that all the rotifers of the oontrol
group lived eleven days and tren gradually started dying until the
whole group became extinct on the thirty-ninth day of the experinent.
'Ihe mean life tiJTe for the control group was 20 . 4 days . 'Ihe data for
the 3- minute and 5-minute irradiated group of rotifers indicate that
the rotifers were affected by the uvexposures. These uv exposures
did not cause any large differences in their life span. 'Ihe mean
life tiJre for the 3-minute irradiated group IV<IS 19.14 days and the
mean life tiJTe for the 5-minute irradiated group was 17 . 13 days.
Statistically, differences of 1 . 26 days and 2.27 days for 3-minute
and 5-minute irradiated groups do not oonstitute a major deviation
fran the oontrol group. This is indicated by Mann-lfuitney U test.
Apart fran that, the qualitative shape of curves is similar to that
of the control group. Hence, it is rrost plausible that the ION
exposure doses cb not effect particular alterations in the rotifer
system. Yet it may still be possible that the ION e><pOsure cbses
do shorten the longevity of rotifers. It is unclear row the ION uv
e><pOsures internally act upon the rotifer cells and at present there
is no canonical theory availabl e to explain the mechanism involved
in the life span shortening by uv radiation.
31
32
'nle curves obtained for the 7-minute and 9-minute irradiated
groups £Xlssess three distinct parts. 'lhe first is the strlden initial
drop in the percent survivin;1 which indicates that the uv exposure
was a~Uy lethal for sare of the rotifers and they were killed
instanUy.
'lhe seoond part oonsists of a plateau. 'lhe oontrol, 3-minute,
5-rninute, 7-minute, and 9-minute irradiated groups all £Xlssess the
plateau, but the 7-minute and 9-minute irradiated groups have a smaller
plateau oanpared to the others. 'lhe plateau in the different groups
show that the percent survivin;1 is constant for awhile. Afterwards the
rotifers started dying but the cause of death is not identifiable by
our techniques. However, the rate of death in different groups of
rotifers does constitute a third distinct part of the curves in
Figure 3. It is obvious that the death rate in the 7-minute and 9-
minute irradiated groups is oonsiderably higher. 'lhis phenarenon of
higher death rate is probably due to the uv-radiation-induced accelera
tion of aging. "Since there is no further cell division after the
hatching of rotifers' eggs, thus any samtic radiation damage incurred
after this time is not subject to repair bY selective re(XlpUlation
!Jy the least injured cells. ,,6 Hence , the uv radiation induced
acceleration of aging. 'lhe rooan life tirne for the 7-minute and 9-
minute irradiated gro\li:3 are 11.5 days and 6.33 days, a diff~nce of
8.9 days and 14.07 days fran the oontrol. 'lhe data fran oontrol, 7-
minute and 9-minute irradiated groups were examined. 'lhe null
hy£Xlthesis was that the number of cases of rotifers alive in oontrol
33
and irradiated groups were the sarre. The alternative hypothesis was
that the nllTlber of rotifers alive in the control group were larger
than the irradiated groups. The Mann-whitney U test gives a highly
significant result. The l evel of significance was 0.05 and the
probability of null hypothesis fran Mann-whitney test was 0.006.
Thus the null hypothesis was rejected in favor of the alternative
hypothesis.
It is clear fran Figure 4 that the 3-mi:nute and 5-minute
irradiated groups of rotifers emulate the b3havior of the control.
The curves possess features similar to those of the control group. It
is pl ausilile that these lo.v-exposures oonstitute a threshold and these
exposures failed to produce singular nutations in the cell structure,
hence in the mean life tine of the rotifers. Figures 5 and 6, which
are the plot of exposures versus 1/1', and the square of the exposures
versus 1/1', also strongly indicate this phenanenon of a threshold.
The rotifers exposed for 7 minutes and 9 minutes display prooounced
effects but there is still infonnation lacking regarding the uv
radiatioo actually absorbed by the rotifers. Also, only very scant
infonnation is available about the uv radiation reaction with a
particular rotifer cell and in what manner the diffp.rent uv exposures
affect their cells.
Fran the present ...ork it i s concluded that ultraviolet exposures
of between 56.7 UJ/ an2 and 170.1 uJ/crn2 reduced the life span of the
rotifer phllodina. In addition, there exists a threshold exposure
which effects a change in the life span of these rotifers. This suggests
the existence of t...o different rrechanisms (at present unkoown) by which
34
ultraviolet radiation can reduce the life span of this particular
organism.
~uggestions for Further Study
It is interesting to study the various IN exposures on rotifers
of different ages and subsequent egg production. The nlllliler of eggs
laid by the i=adiated rotifers and the hatchability of those eggs
should be detenn:ined. The behavior of post-i=adiation generation of
rotifers and the egg production of this generation should be subjected
to detail study. It \>Quld a lso be interesting to study the different
uv exposures on eggs and their hatchability. In this way the radiation
sensitivity of the eggs \>Quld be determined.
It \>QUId also be \>Qrthwhile to Im:>w whether the i=adiated eggs
are capable of repairing the damage incu=ed by the cells due to
radiation. Eggs i=adiated at different stages ""uld provide neoessary
insight into the properties of the division of these cells. If the
eggs are i=adiated at a time much closer to hatching -- probably after
cell division has been cx:crpleted -- the result may be of sane inportance
for ronprehension of the rrec:hani.sm involved.
1. A.M. Rauth, "Effects of Ultraviolet Light on Manmalian Cells in llilture," Current 'Ibpics in Radiation Ilesearch. (North Holand Publishing Cotpany, !\msterdani, 1970, Vol. IV, Ch. 3, p. 86.
35
2. J. CUrtis, Radiobiology (Lon Butten.orths , 1961). Ch. IV, p. 321.
3. H.A. Blair and R.C. Baxter, "Radiation Life Shortening in Drosophila as a Function of Age and Prior Exposure," Radiation Research~, 439 (1970).
4. ~I.J . Lanb, "The Relationship Between Age at Irradiation and Life Shortening in Adult Drosophila", Radiation and Aging (Taylor and Francis Ltd., LonOOn, 1966), Ch. lIt, p. 112.
5. R.C. Baxter and H.A. Blair, "Kinetics of Aging as Revealed by X-RaY-Dose-Lethality Relations in Drosophila," Radiation ReSearch 30,48-70 (1967).
6. J.P. Fowler·"~~~~~~~in~~~~F~~~ (North Holland Publishing a • II, Chapter 7, p. 303.
7. P.M. Failla, "Effects of Radiation on Rotifers Irradiated at Different Ages," Annual Report, Radiological Research Lalx>rato:ry, ColuntJia University (1959).
8. P . M. Failla, "Radiation Response of Rotifers Exposed at Different Stages," Argonne National Lalx>rato:ry Radiological Physics Division, Annual Report, July 1964 through June 1965, ANL-7060.
9. N.D. M9acbw and C.H. Barrows, Jr., "Studies on Aging in a Bdelloid Rotifer." Exp. Zoo 1. 176, 303, (1971).
10 . J. Jagger, Introduction to Res..arch in Ultraviolet Photobiology. (Prentice HaIl, EngIe\ilOd chUs, New Jersey, 1967) Chap. 2, p. 28.
36
BIOGRAPHICAL SKm'Cl!
The author was born in Be1laJ:y, India, He
roved with his parents to Kurnoo1, India, where he attended the local
elarentary school am he was graduated fran the G:>verment ~llslim
High School in 1962. He received the Bachelor of Science degree in
Physics in 1966 fran Sri Venkateswara Uriversity, India. He entered
the Ravishankar Uri versi ty, India and received the /Bster of Science
degree in Physics in 1969. In Septarber of 1970, he worked as a
Junior Lecturer in Physical Sciences in G:>verment Arts College,
OJddapah , India for three years. Since August 1973, he has been at
Western Kentucky Uriversity, Pll"Suing work tcMard the IBster of