β-LG基因外显子2多态性对荷斯坦牛乳成分的影响

目的：为了研究中国荷斯坦奶牛的β乳球蛋白（β-lactoglobulin,β-LG）基因外显子2多态现象对乳产量及成分影响。方法：本实验采用单链构象多态（PCR-SSCP）技术对中国荷斯坦奶牛β-LG基因（NCBI登录号：DQ489319）外显子2进行克隆及多态性研究。结果：8种SSCP带型：ab,abc,abed,abd,abe,abcde,abce和abde型,带型频率分别为：0．14,0．10,0．27,0．23,0．05,0．04,0．11和0．06（P〈0．05）;6个单核苷酸位点：位点1C〉T,位点2T〉C,位点3C〉T,位点4C〉G,位点5C〉A,位点6A〉T或C,且它们的遗传多态信息含量处于中度或高度多态（PIC〉0．25）。结论：中国荷斯坦奶牛β-LG基因外显子2区具有单核苷酸多态,单个核苷酸的改变影响奶牛的生产性能（牛乳产量、乳蛋白和脂肪含量等）。

The effect of genetic polymorphism of the exon 2 of the beta-lactoglobulin gene on the milk composition in Chinese Holstein

Objective： In order to study the effect of the polymorphism at the exon2 region of the β-LG allele gene on milk composition and yield. Methods： The single-strand conformation polymorphism method （PCR-SSCP） was used to analyze for polymorphism the exon2 region of the β-LG gene （NCBI accession number： DQ489319） in Chinese Holstein. Results： Eight SSCP patterns were detected in the fragments： ab, abc, abd, abe, abcd, abce, abde and abcde,and the patterns frequencies as follows： 0.14, 0.10, 0.27, 0.23, 0.05, 0.04, 0.11 and 0.06 （ P 〈0.05）; Six single nucleotide polymorphism （SNP） were detected in this study： sitel C〉 T, site2 T〉 C, site3 C〉 T, site4 C〉 G, site5 C〉 A, site6 A〉 T or C, and the polymorphism information content （PIC） of these SNPs were in median or high polymorphism （PIC〉0.25）. Condusion： These SNPs at the exon2 region of the β-LG gene were remarkably and affected milk performance traits （milk yield, protein and fat contents） in Chinese Holstein.