The DNA repair capabilities of rainbow trout (Salmo gairdneri)
were studied vising the method of autoradiography. Trout were fed a
semi-purified control diet containing 0 ppm, 50 ppm, or 300 ppm
cyclopropenoid fatty acids (CPFA) for 6-9 weeks. Liver slices were
prepared and exposed in vitro to a control treatment, ultraviolet
irradiation (UV), ethidium bromide (EB), UV/EB in succession, or
aflatoxin B₁. The degree of DNA repair was analyzed in terms of
net grains per cell.
Except following the EB treatment, fish on the control diet
revealed an absence of ongoing DNA repair. Trout fed 50 ppm CPFA
exhibited a consistently low level of repair over time following the
in vitro control treatment. Fish fed 300 ppm CPFA revealed a
relatively higher degree of ³H-Me-thymidine incorporation
indicative of induced DNA repair following the in vitro control
treatment, and the degree of repair increased with time on the diet. UV-irradiation caused a marked increase in the degree of induced DNA
repair in 300 ppm CPFA fish at 6 and 7.5 weeks, and in 50 ppm CPFA
fish at 7.5 weeks. Follcwing UV-irradiation, liver slices were
exposed to EB, a DNA intercalating agent used to inhibit normal DNA
replication. However, in contrast to the desired effect, EB caused a
marked decrease in the degree of repair synthesis observed in 300 ppm
CPFA fish at 6 and 7.5 weeks. Indicative of intercalation, the in
vitro EB treatment caused a moderate degree of ³H-Me-thymidine
incorporation in fish fed the control diet. Repair was also induced
in 300 ppm CPFA fish following exposure to EB at 6 and 7.5 weeks.
Aflatoxin B₁ induced DNA repair to various degrees in fish on all
diets at 7.5 and 9 weeks. In comparison to the in vitro control
treatment, it was observed that the degree of induced DNA repair was
decreased significantly - "completely" following the UV, UV/EB, and
EB treatments - in fish fed the 300 ppm CPFA diet for 9 weeks.
In view of the low level of DNA repair observed in rainbow trout
using autoradiography, the repair capabilities were studied using a
more sensitive assay, bromodeoxyuridine (BrdU) photolysis. Isolated
hepatocytes were prepared from fish fed the various diets and exposed
in vitro to a control treatment, UV-irradiation, or
4-nitroquinoline-N-oxide. The obtained results were nonconclusive
indicating technical improvements on the assay need to be made. / Graduation date: 1988
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27103 |
| Date | 30 June 1988 |
| Creators | Collier, John Mark |
| Contributors | Selivonchick, Daniel P. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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