Abolition of the cyclic variations in radiosensitivity during meiosis in a sporulation mutant blocked in premeiotic DNA synthesis.

The response to ultraviolet light (254 nm) of two sporulation mutants during the meiotic process was compared to that of a wild type diploid strain of Saccharomyces cerevisiae. The cyclic pattern for cell killing and rho- induction characteristic of diploid wild type cells persists in a strain able to perform the premeiotic DNA synthesis but which is blocked in the further steps of meiosis (spo8 DMS1). On the contrary, these fluctations are abolished in a derived mutant (spo8 dsm1) which is blocked in the premeiotic DNA synthesis. Under these conditions, the response to cell killing can be dissociated from the observed for rho- induction.