Department of Biology, Stanford University, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 2010 Feb 16;107(7):2977-82. doi: 10.1073/pnas.0912245107. Epub 2010 Jan 28.
Changes in gene expression have been proposed to underlie many, or even most, adaptive differences between species. Despite the increasing acceptance of this view, only a handful of cases of adaptive gene expression evolution have been demonstrated. To address this discrepancy, we introduce a simple test for lineage-specific selection on gene expression. Applying the test to genome-wide gene expression data from the budding yeast Saccharomyces cerevisiae, we find that hundreds of gene expression levels have been subject to lineage-specific selection. Comparing these findings with independent population genetic evidence of selective sweeps suggests that this lineage-specific selection has resulted in recent sweeps at over a hundred genes, most of which led to increased transcript levels. Examination of the implicated genes revealed a specific biochemical pathway--ergosterol biosynthesis--where the expression of multiple genes has been subject to selection for reduced levels. In sum, these results suggest that adaptive evolution of gene expression is common in yeast, that regulatory adaptation can occur at the level of entire pathways, and that similar genome-wide scans may be possible in other species, including humans.
基因表达的变化被认为是许多甚至大多数物种间适应性差异的基础。尽管这种观点越来越被接受，但适应性基因表达进化的例子却很少。为了解决这一差异，我们引入了一种简单的测试方法，用于检测基因表达的谱系特异性选择。将该测试应用于来自酿酒酵母（Saccharomyces cerevisiae）的全基因组基因表达数据，我们发现数百个基因表达水平受到了谱系特异性选择。将这些发现与选择性清除的独立群体遗传证据进行比较表明，这种谱系特异性选择导致了一百多个基因的近期清除，其中大多数导致转录水平升高。对涉及的基因进行检查显示，一个特定的生化途径——麦角固醇生物合成途径，其多个基因的表达受到了降低水平的选择。总之，这些结果表明，酵母中基因表达的适应性进化是普遍存在的，调节适应可以发生在整个途径的水平上，并且类似的全基因组扫描在其他物种（包括人类）中也是可能的。
