牛凝乳酶原基因克隆及序列的进化分析

Cloning and phylogenetic analysis of bovine prochymosin gene

利用RT-PCR克隆获得牛凝乳酶原基因的cDNA序列,测序后与GenBank中凝乳酶原基因进行序列比对和生物信息学分析。序列比对统计分析显示,该基因为牛凝乳酶原B基因,与已知牛和其他哺乳动物的凝乳酶原基因具有很高的同源性,18种哺乳动物凝乳酶原基因密码子一、二、三位点的碱基偏倚度分别为:6.227、1.042和1.456。这表明该基因具有整体保守性和突变位点偏倚性两个特征,可以作为哺乳动物系统进化的研究对象。采用多种方法构建的该基因系统进化树一致表明,偶蹄动物与灵长动物的亲缘关系比偶蹄动物与啮齿动物的亲缘关系更近,比偶蹄动物与食肉动物的亲缘关系更远,并且18种哺乳动物的亲缘关系与动物种系进化关系一致,为哺乳动物系统进化关系研究提供了分子水平的佐证和依据。

The eDNA sequence of bovine proehymosin gene was cloned and sequenced from the abomasums of suckling calf by RT-PCR. The sequence was aligned and bioinformatically analyzed with related sequences in GenBank. The result of sequence analysis revealed that the gene was determined to bovine prochymosin B gene and had the high level of homology with prochymosin gene of other known mammals. The base bias of 18 species of prochymosin gene reduced according to codon position, and the gene provided us with excellent material ofphylogenetic research. Thus, the phylogenetic tree of 18 species of prochymosin gene was used to discuss and offer testimony to phylogenetic relationship of 11 mammals.