The evolution of gene expression levels in mammalian organs

摘要

基因组分析能够揭示有可能决定着物种间差别rn的蛋白编码变化，但物种之间基因型差别中很rn多都是影响基因表达的调控性突变所造成的结rn果。Brawand等人利用高吞吐量RNA测序方法rn来研究来自所有主要哺乳动物分支的10个物种rn的六大器官(皮层、小脑、心脏、肾脏、肝脏rn和睾丸)中哺乳动物转录组的演化动态。他们rn所取得的发现之是器官和物种之间转录组差rn异的程度，同时他们还识别出了可能是由选择rn性驱动的表达开关，这些开关可能决定了特定rn器官的生物学特征。%Changes in gene expression are thought to underlie many of the phenotypic differences between species. However, large-scale analyses of gene expression evolution were until recently prevented by technological limitations. Here we report the sequencing of polyadenylated RNA from six organs across ten species that represent all major mammalian lineages (placentals, marsupials and monotremes) and birds (the evolutionary outgroup), with the goal of understanding the dynamics of mammalian transcriptome evolution. We show that the rate of gene expression evolution varies among organs, lineages and chromosomes, owing to differences in selective pressures: transcriptome change was slow in nervous tissues and rapid in testes, slower in rodents than in apes and monotremes, and rapid for the X chromosome right after its formation. Although gene expression evolution in mammals was strongly shaped by purifying selection, we identify numerous potentially selectively driven expression switches, which occurred at different rates across lineages and tissues and which probably contributed to the specific organ biology of various mammals.