Effect of gamma and alpha irradiation on survival of wild-type and sensitive mutants of yeast.

Survival curves have been obtained for haploid and diploid Saccharomyces cerevisiae of the wild-type strain and the sensitive mutant rad51-1 exposed to gamma-rays and alpha-particles. The difference in radio-sensitivities of the wild-type diploid strain and the homozygous rad51-1 mutant was significantly higher after low-LET radiation than after high-LET radiation. This was not true for haploid strains. The liquid-holding recovery of irradiated cells was greater for gamma-ray-induced damage than for damage inflicted by alpha-particles. The value of the RBE of high-LET radiation was correlated with cell-repair capacity.