Genomic convergence toward diploidy in Saccharomyces cerevisiae.
Genomic convergence toward diploidy in Saccharomyces cerevisiae.
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DOI：
10.1371/journal.pgen.0020145
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发表时间：
2006-09-22
期刊：
影响因子：
4.5
通讯作者：
Otto SP
中科院分区：
文献类型：
--
作者：
Gerstein AC;Chun HJ;Grant A;Otto SP
基因组大小是任何生物的基本方面，受到各种突变和选择压力的影响。我们研究了单倍体，二倍体，和四倍体最初的酿酒酵母等基因系的基因组大小的演变。在~ 1，800代有丝分裂的过程中，我们观察到所有复制系中的二倍体DNA含量的收敛。这种收敛在无压力和有压力的环境中都能观察到，尽管收敛的速率取决于初始倍性和进化环境。比较基因组杂交与微阵列显示近整倍体DNA含量的实验结束。作为S.尽管酿酒酵母主要是二倍体，但该实验提供了基因组大小进化受到限制的证据，选择有利于酵母进化过去典型的基因组内容。基因组大小是所有物种的一个基本方面，并有可能影响许多个体特征，如细胞大小，世代时间，生态耐受性和生殖特征。虽然基因组大小在物种之间有很大的差异，但塑造基因组大小进化的力量却知之甚少。在这里，我们提供了一个约1,800代进化实验的结果，使用芽殖酵母S。酿酒酵母具有其基因组的一个、两个或四个拷贝（分别为单倍体、二倍体和四倍体）。令人惊讶的是，我们发现所有的单倍体和四倍体品系都向二倍体靠拢，这是S.到实验结束时，啤酒厂。进一步的实验表明，当基因组大小从四倍体变为二倍体时，整组染色体都丢失了。我们的研究结果表明，基因组的大小是受选择作用对历史基因组大小的变化。
Genome size, a fundamental aspect of any organism, is subject to a variety of mutational and selection pressures. We investigated genome size evolution in haploid, diploid, and tetraploid initially isogenic lines of the yeast Saccharomyces cerevisiae. Over the course of ~1,800 generations of mitotic division, we observed convergence toward diploid DNA content in all replicate lines. This convergence was observed in both unstressful and stressful environments, although the rate of convergence was dependent on initial ploidy and evolutionary environment. Comparative genomic hybridization with microarrays revealed nearly euploid DNA content by the end of the experiment. As the vegetative life cycle of S. cerevisiae is predominantly diploid, this experiment provides evidence that genome size evolution is constrained, with selection favouring the genomic content typical of the yeast's evolutionary past. Genome size is a fundamental aspect of all species and has the potential to influence a number of individual characteristics such as cell size, generation time, ecological tolerances, and reproductive traits. Although genome sizes range widely among species, the forces shaping the evolution of genome size are only poorly known. Here we provide the results of an ~1,800 generation evolution experiment using lines of the budding yeast S. cerevisiae with either one, two, or four copies of their genome (haploid, diploid and tetraploid, respectively). We found, surprisingly, that all haploid and tetraploid lines converged toward diploidy, the historical state of S. cerevisiae, by the end of the experiment. Further experiments suggest that entire sets of chromosomes were lost as genome size changed from tetraploid to diploid. Our results suggest that genome size is constrained by selection acting against changes from the historical genome size.
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