[Ultraviolet irradiation of Saccharomyces cerevisia: variations during meiosis in survival and in the induction of the cytoplasmic "petite" mutation].

Cyclic variations in sensitivity to killing and cytoplasmic "petite' (p-) induction by ultraviolet light occur during the meiosis of Saccharomyces cerevisiae. Maximal sensitivity to killing coincides with the period of meiotic nuclear DNA synthesis. Cyclic fluctuations in p- induction could not be correlated with known meiotic events and the pattern could vary temporarily from batch to batch. A dark liquid holding of irradiated cells aided the repair of lethal lesions but on the other hand an enhancement of "petite" induction was observed at all meiotic stages.