Further Studies on the Influence of Oxygen on X-ray-induced rearrangement in Drosophila Oocytes

Summary

Alteration of the metabolism of Drosophila oocytes greatly affects the induction of structural changes by x-rays. Females 2–3 days of age contain oocytes whose chromosomes restitute and rearrange rapidly, whereas no evidence for restitution within the intervals studied was found in samples of oocytes from females 8–9 days old at the time of irradiation. The effect of nitrogen as a post- or inter-treatment showed, however, that for both young and old oocytes there was more restitution in air than in nitrogen. Both young and old oocytes show reduced rearrangement frequencies when irradiations were performed in nitrogen, and increased rearrangement frequencies when a fractionated irradiation was performed with the flies maintained in a nitrogen environment between irradiations. These different effects of anoxia are discussed.