陕西地区荷斯坦牛Mx1基因外显子多态性分析

牛Mx1基因位于1号染色体上,含有14个外显子,编码648个氨基酸。研究以346头陕西地区荷斯坦牛为研究对象,根据GenBank所提供的牛Mx1基因序列,设计15对引物,采用混合DNA池扩增测序和PCR-RFLP的方法对牛Mx1基因的14个外显子进行多态性分析。结果表明,4个SNPs,分别位于外显子3（g.843330T〉C,g.843411A〉G）、外显子4（g.844048C〉T）和外显子7（g.851325T〉C）。其中,外显子4（g.844048C〉T）为同义突变;外显子3（g.843330T〉C,g.843411A〉G）两个位点的突变分别导致了异亮氨酸（Ile）向苏氨酸（Thr）、谷氨酸（Glu）向精氨酸（Arg）的突变;外显子7（g.851325T〉C）位点的突变导致亮氨酸（Leu）变为脯氨酸（Pro）。4个SNPs位点都存在三种基因型,但纯合子的突变频率较低。4个SNPs位点共构建了11种单倍型,其中以H6为最主要的单倍型。结果显示,陕西地区荷斯坦牛Mx1基因存在较丰富的多态性,这将为Mx1基因结构和功能的研究以及将来在育种实践中的应用提供基础资料。

Polymorphism of Mx1 Gene among Holstein Cows in Shaanxi Province

Bovine Mxl gene is located on the 1st chromosome which contains 14 exons encoding 648 a- mino acids. In this study, fifteen pair primers were designed, based on previously published bovine Mxl gene sequence, to amplify and sequence all 14 exons of Mxl gene from holstein cows in Shaanxi Province＇s. 346 samples were analyzed using DNA pool as the template. Four SNPs including exon 3 （g. 843330 T〉 C, g. 843411 A〉G）, exon 4 （g. 844048 C：〉T）, exon 7 （g. 851325 T〉C） were detected which were all transitions. PCR-RFLP method was applied to genotype the four SNPs. The SNP mutation in exon 4 is synonymous, but the other mutions cause three amino acid changes： Ile to Thr in exon 3 （g. 843330 T〉 C） 〉 Glu to Arg in exon 3 （g. 843411 A〉G） 〉 Leu to Pro in exon 7 （g. 851325 T〉C）. Eleven haplotypes （H1- Hll） were obtained based on four SNPs and the haplotype H6 was predominant. The results showed that there were abundant genetic polymorphism in the Mxl gene among holstein cows in Shaanxi province, which was helpful to the research of the structure and function of Mxl gene and its application in practice in future.