Y染色体消亡 女科学家找到原因

　　

生物通报道，宾夕法尼亚大学生物系与基因组学系的研究者在性染色进化变异的机制研究上取得进展，相关成果Evolution and Survival on Eutherian Sex Chromosomes公布在最近的一期PLoS Genetics上。

 

一直以来学者们发现男性的特殊染色体Y染色体总是在不断地丢失基因，与它同源的X染色体却一直没有类似的情况，Y染色体上的基因越来越少，而X染色体上的基因却极少丢失。

 

就这一独特的现象今年5月澳大利亚基因研究专家詹妮弗·格雷夫斯就语出惊人，如果Y染色体继续消亡可能导致维持男性特征的基因丢失，最终导致男性灭绝。不过目前人们还不必担忧，因为格雷夫斯表示这一变化将发生在500万年以后。

 

宾夕法尼亚大学生物系的首席科学家Kateryna D. Makova研究小组却解开了性染色体变化的机制。Kateryna D. Makova目前任首席研究员（PI），她主持的实验室主要研究DNA突变，染色体变异等课题。

 

在这次的研究中，Kateryna D. Makova发现由于不断的进化，保持高度的进化效率男性的Y染色体的变异率很高，而女性的X染色体变异率很低。这与性染色体特殊的mRNA/蛋白表达模式有关，这些差异使得性染色体的进化效率有极大的差异。

 

研究小组下一步将继续研究Y染色体的进化模式，期望能建立一个Y染色体进化的计算机模型，得以知晓Y染色体在多少年后可能完全消亡。那一天可能就是男性消亡的一天！

（生物通  小茜）

 

生物通推荐原文检索：

Evolution and Survival on Eutherian Sex Chromosomes

 

Melissa A. Wilson1,2,3, Kateryna D. Makova1,2,3*

1 Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America, 2 Center for Comparative Genomics and Bioinformatics, Pennsylvania State University, University Park, Pennsylvania, United States of America, 3 The Integrative Biosciences Program, Pennsylvania State University, University Park, Pennsylvania, United States of America

【Abstract】

Since the two eutherian sex chromosomes diverged from an ancestral autosomal pair, the X has remained relatively gene-rich, while the Y has lost most of its genes through the accumulation of deleterious mutations in nonrecombining regions. Presently, it is unclear what is distinctive about genes that remain on the Y chromosome, when the sex chromosomes acquired their unique evolutionary rates, and whether X-Y gene divergence paralleled that of paralogs located on autosomes. To tackle these questions, here we juxtaposed the evolution of X and Y homologous genes (gametologs) in eutherian mammals with their autosomal orthologs in marsupial and monotreme mammals. We discovered that genes on the X and Y acquired distinct evolutionary rates immediately following the suppression of recombination between the two sex chromosomes. The Y-linked genes evolved at higher rates, while the X-linked genes maintained the lower evolutionary rates of the ancestral autosomal genes. These distinct rates have been maintained throughout the evolution of X and Y. Specifically, in humans, most X gametologs and, curiously, also most Y gametologs evolved under stronger purifying selection than similarly aged autosomal paralogs. Finally, after evaluating the current experimental data from the literature, we concluded that unique mRNA/protein expression patterns and functions acquired by Y (versus X) gametologs likely contributed to their retention. Our results also suggest that either the boundary between sex chromosome strata 3 and 4 should be shifted or that stratum 3 should be divided into two strata.