THE YEAST 2-MU PLASMID - STRATEGIES FOR THE SURVIVAL OF A SELFISH DNA
THE YEAST 2-MU PLASMID - STRATEGIES FOR THE SURVIVAL OF A SELFISH DNA
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DOI：
10.1007/bf00338076
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发表时间：
1986-01-01
期刊：
影响因子：
--
通讯作者：
OLIVER, SG
中科院分区：
文献类型：
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作者：
MEAD, DJ;GARDNER, DCJ;OLIVER, SG
酵母的名称。通过证明在连续培养中生长的单倍体酵母（Saccharomyces cerevisiae）群体的质粒随指数动力学丢失，已经证实了circle是一个“自私”的DNA分子。我们发现，与含有质粒的酵母细胞相比，无质粒酵母细胞的生长速度优势约为1.5%-3%。这一发现使得这种自私的DNA在酵母菌株中的普遍存在令人费解。另外两个因素可能解释了它的生存。首先，通过允许单倍体群体周期性地进入固定期来降低质粒损失率。其次，不可能从二倍体酵母菌株中分离出无质粒分离体。竞争实验表明，二倍体的稳定性是在分离水平上获得的，与含有质粒的二倍体细胞相比，无质粒的二倍体细胞具有选择优势。自然界中的酵母细胞通常是同型的，必须经常经历二倍体和固定期。2。质粒似乎已经进化出了一种生存策略，它利用了宿主生命周期的这两个特征。
The designation of the yeast 2 .mu. circle as a "selfish" DNA molecule has been confirmed by demonstrating that the plasmid is lost with exponential kinetics from haploid yeast [Saccharomyces cerevisiae] populations grown in continuous culture. We show that plasmid-free yeast cells have a growth rate advantage of some 1.5%-3% over their plasmid-containing counterparts. This finding makes the ubiquity of this selfish DNA in yeast strains puzzling. Two other factors probably account for its survival. First, the rate of plasmid loss was reduced by allowing haploid populations to enter stationary phase periodically. Second, it was not possible to isolate a plasmid-free segregant from a diploid yeast strain. Competition experiments demonstrated that stability in a diploid is conferred at the level of segregation and that plasmid-free diploid cells are at a selective advantage compared with their plasmid-containing counterparts. Yeast cells in nature are usually homothallic and must frequently pass through both diploid and stationary phases. The 2 .mu. plasmid appears to have evolved a survival strategy which exploits these two features of its host''s life cycle.