THE INDUCTION OF DOMINANT LETHAL MUTATIONS IN X-IRRADIATED DROSOPHILA VIRILIS OOCYTES
To study the effect of various gases and combinations of gases on the induction of dominant lethal mutations in x irradiated Drosophila virilis oocytes two stages of oocytes were used. Females containing stage 7 oocytes were irradiated with 2000 r and females cortaining stage 14 oocytes were irradiated with 250 r. The flies were irradiated in the presence of 1 or 10 atm of argon, helium, methane, carbon monoxide, air, oxygen, or combinations of 9 atm of argon, helium, or methane pius 1 atm of oxygen. The percentage non-hatch was attributed to the induction of dominant lethal mutations. It was found that the LD/sub 50/ of mature Drosophila virilis oocytes (stage 14) irradiated in air is about 350 r while the LD/sub 50/ for stage 7 oocytes irradiated in air is about 2000 r. This demonstrated that stage 14 oocytes are much more sensitive to radiation damage than stage 7. Stages 7 or 14 Drosophila virilis oocytes were irradiated in conditions of increased oxygen tension (10 atm air, 1 or 10 atm of oxygen). The groups showed an increased induction of dominant lethals as scored by percentage non-hatch, when compared to oocytes irradiated in one atmosphere of air. Stage 7 or 14 Drosophila virilis oocytes irradiated in the presence of 9 atm of argon, helium, or methane with 1 atm of oxygen showed a large decrease in induced dominant lethals when compared to oocytes irradiated in 1 atm of pure oxygen. This demonstrates that argon, helium, and methane have a protective effect against the induction of dominart lethal mutations. Stage 7 or 14 Drosophila virilis oocytes irradiated in the absence of oxygen (presence of 1 or 10 atm of argon, helium, methane, or carbon monoxide) showed a large decrease in the induction of dominant lethal mutations when compared to oocytes irradiated in 1 atm of air, thus showing that decreased oxygen in the oocyte leads to decreased damage to the cell. Fewer dominant lethals were induced when the oocytes were irradiated in 10 atm of argon, helium, methane, or carbon monoxide as compared to oocytes irradiated in one atmosphere of the same gas. In preliminary investigations stage 7 Drosophila virilis oocytes were irradiated in the presence of 10 atm of carbon monoxide with fractionated doses. A slight increase in the percentage hatch of the groups irradiated in two fractions as compared to the groups irradiated in one dose was observed. The differences in percentage hatch of the groups irradiated in fractionated doses were not statistically significant. Tentative evidence was presented that indicates that anoxia during fractionated doses or irradiation in stage 7 oocytes does not increase the frequency of induced dominant lethal mutations. (Dissertation Abstr., 23: No. 5, Nov. 1962)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-007886
- OSTI ID:
- 4739866
- Resource Relation:
- Other Information: Thesis. Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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