Saeki T, Machida I, Nakai S
Mutat Res. 1980 Dec;73(2):251-65. doi: 10.1016/0027-5107(80)90192-x.
Genetic mechanisms(s) of gamma-ray resistance of the diploid and budding haploid cells of S. cerevisiae were investigated, with special reference to mitotic recombination, by examining 11 rad mutant strains. The radiosensitivity of the diploid was markedly enhanced in certain gamma-ray-sensitive rad mutants, whereas the sensitivity of the haploid was not so enhanced in these rad mutants. These enhanced sensitivities of diploids were irrespective of their own haploid sensitivities. From these results, the existence of a mechanism of diploid-specific recovery was postulated. The magnitude of diploid radioresistance in rad mutants was positively correlated with the ability for the induction of mitotic recombinational events which were controlled by RAD genes belonging to the RAD-51 genetic pathway. The genetic mechanism(s) of the diploid recovery after gamma-irradiation are probably related to recombinational processes between the homologous chromosomes leading to reciprocal recombination or non-reciprocal gene conversion. Furthermore, the higher radioresistance of budding cells in comparison with the non-budding cells was also correlated to the diploid radioresistance with a few exceptions. Consequently, the mechanism(s) of budding radioresistance similar to the diploid recovery seems to be related to mitotic recombinational processes.
通过检测11个rad突变菌株，研究了酿酒酵母二倍体和出芽单倍体细胞对γ射线抗性的遗传机制，特别关注有丝分裂重组。在某些对γ射线敏感的rad突变体中，二倍体的放射敏感性显著增强，而这些rad突变体中单倍体的敏感性并未如此增强。二倍体的这些增强的敏感性与它们自身单倍体的敏感性无关。基于这些结果，推测存在一种二倍体特异性恢复机制。rad突变体中二倍体抗辐射性的大小与诱导有丝分裂重组事件的能力呈正相关，这些事件由属于RAD-51遗传途径的RAD基因控制。γ射线照射后二倍体恢复的遗传机制可能与同源染色体之间的重组过程有关，导致相互重组或非相互基因转换。此外，除少数例外，出芽细胞比未出芽细胞具有更高的抗辐射性也与二倍体抗辐射性相关。因此，与二倍体恢复相似的出芽抗辐射机制似乎与有丝分裂重组过程有关。
