Zakharov I A, Kasinova G V, Koval'tsova S V
Genetika. 1983;19(1):49-57.
The effect of UV- and gamma-irradiation on the survival and intragenic mitotic recombination (gene conversion) of 5 radiosensitive mutants was studied in comparison with the wild type. The level of spontaneous conversion was similar for RAD, rad2 and rad15, mutations xrs2 and xrs4 increasing and rad54 significantly decreasing it. The frequency of conversion induced by UV-light was greater in rad2, rad15 and xrs2 mutants and lower in xrs4, as compared to RAD. Gamma-irradiation caused induction of gene conversion with an equal frequency in RAD, rad2, rad15. Xrs2 and xrs4 mutations slightly decreased gamma-induced conversion. In rad54 mutant, UV-and gamma-induced conversion was practically absent. In the wild type yeast, a diploid strain is more resistant than a haploid, whereas in rad54 a diploid strain has the same or an increased sensitivity, as compared to a haploid strain (the "inverse ploidy effect"). This effect and also the block of induced mitotic recombination caused by rad54 indicate the presence in the yeast Saccharomyces cerevisiae of repair pathways of UV- and gamma-induced damages acting in diploid cells and realised by recombination. The data obtained as a result of many years' investigation of genetic effects in radiosensitive mutants of yeast are summarised and considered.
研究了紫外线和γ射线辐照对5种辐射敏感突变体的存活及基因内有丝分裂重组（基因转换）的影响，并与野生型进行了比较。RAD、rad2和rad15的自发转换水平相似，xrs2和xrs4突变使其增加，而rad54则使其显著降低。与RAD相比，紫外线诱导的rad2、rad15和xrs2突变体的转换频率更高，xrs4的转换频率更低。γ射线辐照在RAD、rad2、rad15中以相同频率诱导基因转换。Xrs2和xrs4突变略微降低了γ射线诱导的转换。在rad54突变体中，紫外线和γ射线诱导的转换几乎不存在。在野生型酵母中，二倍体菌株比单倍体更具抗性，而在rad54中，与单倍体菌株相比，二倍体菌株具有相同或更高的敏感性（“反倍性效应”）。这种效应以及rad54对诱导有丝分裂重组的阻断表明，酿酒酵母中存在紫外线和γ射线诱导损伤的修复途径，这些途径在二倍体细胞中起作用并通过重组实现。总结并考虑了多年来对酵母辐射敏感突变体遗传效应研究所得的数据。
