Moustacchi E, Perlman P S, Mahler H R
Mol Gen Genet. 1976 Nov 17;148(3):251-61. doi: 10.1007/BF00332899.
A mutant of Saccharomyces cerevisiae has been isolated which, though exhibiting a normal response to nuclear genetic damage by ultraviolet light (UV), is more sensitive than its wild type specifically in the production of the cytoplasmic (rho-) mutation by this agent. Some of the features of this mutation which has been designated uvsrho 5 are: i) The mutation is recessive, it exhibits a Mendelian, and hence presumably nuclear, pattern of segregation, but manifests its effects specifically and pleiotropically on mitochondrial functions. ii) Mutant cells resemble their wild type parents in a) growth characteristics on glucose; b) in their UV induced dose response to lethality or nuclear mutation and c) the ability of their mitochondrial genome, upon mating with appropriate testers, of transmitting and recombining various markers, albeit with enhanced efficiency. Similarly, d) they are able to modulate the expression of mitochondrial mutagenesis by ethidium bromide. Thus their mitochondrial DNA appears genetically as competent as that of the wild type. iii) Mutant cells differ from their wild type parents in a) growth characteristics on glycerol; b) susceptibility to induction of the mitochondrial (rho-) mutation by various mutagens, in that the rate of spontaneous mutation is slightly and that by UV is significantly enhanced, whild that by ethidium bromide is greatly diminished. Conversely, c) modulating influences resulting in the repair of initial damage are diminished fro UV and stimulated in the case of Berenil. iv) The amount of mitochondrial DNA per cell appears elevated in the mutant, relative to wild type, and its rate of degradation subsequent to a mutagenic exposure to either UV or ethidium bromide is diminished. v) A self-consistent scheme to account for this and all other information so far available for the induction and modulation of the (rho-) mutation is presented. In a previous study it was shown that some nuclear mutants of Saccharomyces cerevisiae, more sensitive to lethal damage induced by ultraviolet light (rad) than their parent wild type (RAD), also exhibit a concomitant modification in sensitivity to both nuclear and cytoplasmic genetic damage (Moustacchi, 1971). However, another class of rad mutants respond to the induction of the cytoplasmic "petite" also designated as rho- (or rho-) mutation by UV in a manner indistinguishable from that of the RAD strain. One possible interpretation of this last observation is that some of the steps in the expression of the UV damage on mitochondrial (mt)DNA may be governed by other nuclear and cytoplasmic genetic determinants, the products of which may then act specifically on mitochondrial lesions. If this assumption is correct, it should be possible to find mutants with a normal response to nuclear damage but specifically UV-sensitive towards induction of (rho-)...
已分离出酿酒酵母的一种突变体，该突变体虽然对紫外线（UV）引起的核遗传损伤表现出正常反应，但在该诱变剂诱导细胞质（rho-）突变的过程中，比其野生型更敏感。这种已命名为uvsrho 5的突变的一些特征如下：i）该突变是隐性的，呈现孟德尔式分离模式，因此推测是核遗传模式，但对线粒体功能有特异性且多效性的影响。ii）突变细胞在以下方面与其野生型亲本相似：a）在葡萄糖上的生长特性；b）对紫外线诱导的致死性或核突变的剂量反应；c）其线粒体基因组在与合适的测试菌株交配时传递和重组各种标记的能力，尽管效率有所提高。同样，d）它们能够通过溴化乙锭调节线粒体诱变的表达。因此，它们的线粒体DNA在遗传上似乎与野生型一样有活性。iii）突变细胞与其野生型亲本的不同之处在于：a）在甘油上的生长特性；b）对各种诱变剂诱导线粒体（rho-）突变的敏感性，即自发突变率略有增加，紫外线诱导的突变率显著提高，而溴化乙锭诱导的突变率大大降低。相反，c）紫外线导致的初始损伤修复的调节影响减弱，而贝尼尔的情况则受到刺激。iv）相对于野生型，突变体细胞中每个细胞的线粒体DNA含量似乎升高，并且在受到紫外线或溴化乙锭诱变暴露后其降解速率降低。v）提出了一个自洽的方案来解释这种情况以及目前可获得的关于（rho-）突变诱导和调节的所有其他信息。在先前的一项研究中表明，酿酒酵母的一些核突变体比其亲本野生型（RAD）对紫外线（rad）诱导的致死损伤更敏感，同时对核遗传损伤和细胞质遗传损伤的敏感性也有相应改变（穆斯塔奇，1971）。然而，另一类rad突变体对紫外线诱导的细胞质“小菌落”（也称为rho-（或rho-）突变）的反应与RAD菌株无法区分。对最后这一观察结果的一种可能解释是，紫外线对线粒体（mt）DNA损伤表达的某些步骤可能受其他核遗传和细胞质遗传决定因素的控制，其产物可能随后特异性作用于线粒体损伤。如果这一假设正确，那么应该有可能找到对核损伤有正常反应但对（rho-）诱导特别敏感的突变体……
