Emerson J J, Kaessmann Henrik, Betrán Esther, Long Manyuan
Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.
Science. 2004 Jan 23;303(5657):537-40. doi: 10.1126/science.1090042.
Mammalian sex chromosomes have undergone profound changes since evolving from ancestral autosomes. By examining retroposed genes in the human and mouse genomes, we demonstrate that, during evolution, the mammalian X chromosome has generated and recruited a disproportionately high number of functional retroposed genes, whereas the autosomes experienced lower gene turnover. Most autosomal copies originating from X-linked genes exhibited testis-biased expression. Such export is incompatible with mutational bias and is likely driven by natural selection to attain male germline function. However, the excess recruitment is consistent with a combination of both natural selection and mutational bias.
自从从祖先常染色体进化而来后，哺乳动物的性染色体经历了深刻的变化。通过研究人类和小鼠基因组中的逆转座基因，我们证明，在进化过程中，哺乳动物的X染色体产生并招募了数量极多的功能性逆转座基因，而常染色体的基因更替率较低。大多数源自X连锁基因的常染色体拷贝表现出睾丸偏向性表达。这种输出与突变偏向不相符，很可能是由自然选择驱动以实现雄性生殖系功能。然而，过量的招募与自然选择和突变偏向的共同作用是一致的。
