SRY基因在人猿超科和旧大陆猴中具有不同的进化规律

Different Evolution Rule of SRY Gene Between Hominoid and Old World Monkey

通过ＰＣＲ扩增、测序，得到了白臀叶猴和红面猴的ＳＲＹ基因全序列。结合现有的灵长类其他物种序列进行分析，验证了ＨＭＧ盒的保守性。通过构建系统发育树，比较旧大陆猴和人猿超科两个类群内和类群间ＨＭＧ盒侧翼序列Ｋａ／Ｋｓ的比率。有趣的是，人猿超科两物种比较呈现较高的Ｋａ／Ｋｓ比值，但在旧大陆猴中及旧大陆猴与狨猴间的Ｋａ／Ｋｓ比值显著低于人猿超科的，呈现很不同的格局。同时，对于ＨＭＧ盒序列，Ｋａ／Ｋｓ比值在人猿超科中也有明显的上升趋势。结果表明，人猿超科中异义替换率高于同义替换率的现象（正选择）不是灵长类中近缘物种间的现象，也不是灵长类中的系统偏差，而可能与基因的功能变化有关。同时，正选择作用于ＳＲＹ基因可能始于人猿超科分化的初期。

The complete SRY gene of P. nemaeus and M arctiodes were amplified by using PCR and sequenced. Combined with the same regions of other primate animals, sequence analysis confirmed the conservation of HMGbox. In molecular phylogenetic tree constructed. we made the Ka / Ks value pairwise comparison of HMGbox flanking sequences both intra-and inter- Hominoid and the Old World monkey. TO our interest, the pairwise comparison of species in Hominoid suggested a higher Ka/Ks ratio than that in the Old World monkey or between the Old World monkey and marmoset, which showed existent of different pattern of evolution. In addition, in Hominoid Ka/ Ks ratio for HMGbox sequences was obviously on the increase. The rate of nonsynonymous substitutions per nonsynonymous site is faster than that of synonymous substitutions per synonymous site in Hominoid (driven by positive directional selection). Our analysis suggested that it might be resulted from functional change of this gene and the system error or the close relationship among Hominoid species. It is also supposed that the positive selection was functioned at the beginning of the divergence of Hominoid species.