运用PCR分段扩增测序法,获得普通牛、瘤牛、牦牛、大额牛、水牛(沼泽型和河流型)MSTN基因编码区全序列,进而分析编码区序列的分子进化特征.结果显示,牛MSTN基因编码区全序列长1 128 bp,种内核苷酸突变率为0～0.35%,种间核苷酸突变率为0.08%～1.2%.MSTN基因编码区序列存在密码子使用偏好性,29个偏好性密码子约占密码子使用总数的9.2%.核苷酸的替代以转换为主,转换/颠换比为2.9.非同义突变位点远少于同义突变位点,同义与非同义替代速率比全部小于或等于1,表明MSTN基因编码区序列并未受到达尔文正向选择的影响,却受到一定的负向选择作用.分子进化树显示,水牛、瘤牛独自成类并与其他牛种显著分化;普通牛、牦牛、大额牛间的序列分化程度并不明显,但有可能在进化过程中逐步产生明显的分化.
We obtained complete coding sequence of myostatin gene from Bos taurus, Bos indicus, Bos grunniens, Bos f rontalis and Bubalus bubalis (swamp buffalo and river buffalo) by PCR fragments sequencing method. The molecular evolution characters of CDS of myostatin gene were analyzed. The result showed that CDS of bovine MSTN gene was 1 128 bp in length. The mutation rate within species was between 0 and 0. 35 %,while the mutation rate between species was between 0. 08 % and 1. 42 %. The codon usage bias phenomenon arosed and the 29 preferenced codon possessed about 49. 2 % of the total preferenced codons. The predominant substitution model of nucleotide was transition and the ratio of transition and transversion was 2. 9. Nonsynonymous sites were far less than synonymous sites. The ratio of synonymous and nonsynonymous substitution were all less or equal to one manifesting that it did not effected by Darwin positive selec2 tion.But some sites affected by negative selection.Molecular tree showed that haplotypes from Bubalus bubalis and Bos indicus clustered on their own and there were apparent differentiation between Bubalus bubalis, Bos indicus and other bovine species. There was no apparent differentiation among Bos taurus,Bos grunniens,Bos f rontalis and they maybe pro2 duced apparent differentiation gradually in the process of evolution.
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