摘要
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.
基金
国家自然科学基金
中科院重大项目基金
关键词
SRY基因
进化
正选择
人猿超科
旧大陆猴
SRY gene
evolution
positive selection
Hominoid
the Old World monkey