Genetic load of the yeast Saccharomyces cerevisiae under diverse environmental conditions
Genetic load of the yeast Saccharomyces cerevisiae under diverse environmental conditions
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DOI：
10.1111/j.1558-5646.1999.tb04577.x
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发表时间：
1999-12-01
期刊：
影响因子：
3.3
通讯作者：
Korona, R
中科院分区：
文献类型：
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作者：
Korona, R
通过测定酵母错配修复缺陷菌株的最大生长速率，估计了自发突变积累的适应度效应。测试了几种具有不同能量基质、营养条件和温度的环境。在大多数条件下，单倍体菌株的遗传负荷约为20-30%。由于这种明显的影响是由相对较小的损伤（点突变）引起的，可能影响不到1%的基因，酵母基因组对DNA损伤的抵抗力似乎相当有限。环境之间的适应性转变是有序的，从某种意义上说，在所有环境中，一些菌株往往比其他菌株更适合或更不适合。其中一种环境（极高的温度，38摄氏度）对积累突变的菌株有压力，因为其中一些菌株停止生长，而无突变的菌株只受到适度影响。这些结果表明，随机点突变的影响是实质性的，通常不依赖于特定的环境。然而，在压力条件下，自然选择在清除突变方面可能特别有效，如果这些突变普遍存在，可能会减慢突变积累的速度。
Fitness effect of spontaneous mutations accumulated in mismatch-repair deficient strains of yeast was estimated by measuring their maximum growth rate. Several environments with different energetic substrates, nutritional conditions, and temperature were tested. Genetic load of haploid strains was about 20-30% under most of these conditions. Because such a pronounced effect was caused by relatively small lesions (point mutations) affecting probably less than 1% of genes, resistance of the yeast genome to DNA damage appears to be rather limited. Fitness transitions among environments were orderly, in the sense that some strains tended to be more or less fit than others in all circumstances. One of the environments (an extremely high temperature, 38 degrees C) was stressful to the strains that accumulated mutations, as some of them stopped to grow, whereas the mutation-free strains were only moderately affected. These results imply that the impact of random point mutations is substantial and generally not dependent on a particular environment. Under stressful conditions, however, natural selection may be especially effective in purging mutations that, if commonly met, could slow down the rate of mutation accumulation.