Phenomenon of life span instability in Drosophila melanogaster: II. Change in rhythm of natural variations of life span after single exposure to gamma-irradiation.

The dynamics of life span (LS) have been studied in successive generations of postirradiation and control groups of Drosophila melanogaster, strain D-32, after a single exposure to Co60 gamma-quantum irradiation. It has been shown using mathematical procedures that in all postirradiation generations, with one exception, survival curves retain their canonical shape. This is indicative of the unchangeable nature of LS distribution. The mean LS of the progeny of irradiated parents either coincides with control values or can be higher or lower. Moreover, single irradiation results in an altered time-scanning of LS variations in successive generations as compared with controls. The possible origin of LS instability is discussed.