云南高峰牛MHC-DQB基因外显子2遗传多态性分析

本研究采用PCR直接测序和PCR-RFLP法研究了云南高峰牛MHC-DQB基因外显子2(DQB.2)的遗传多态性,并利用DNAMAN软件分析了云南高峰牛与部分物种DQB.2相应核苷酸序列的同源性。结果发现,共检测到了17个等位基因,其中Hae Ⅲ酶切位点存在10种基因型,由A、B、C、D和E 5个复等位基因控制;RsaⅠ酶切位点存在22种基因型,由A、B、C、D、E、F、G、H、I、J和K共11个复等位基因控制;TaqⅠ酶切位点只出现了1种基因型。分析发现,云南高峰牛DQB.2基因的12、25、63、96、106、126、152、156、165、204位的碱基表现出了多态性。所分析的物种该基因片段大小相同均为270 bp,云南高峰牛第224位碱基缺失及236位碱基插入现象。云南高峰牛与人、猪、马、绵羊、黄牛×瘤牛的核苷酸序列的同源性分别为81.4%、83.3%、78.1%、87.7%、86.6%。经χ²检验结果表明,Hae Ⅲ和TaqⅠ酶切位点处于Hardy-Weinberg平衡状态(P＞0.05),而RsaⅠ酶切位点则未达到Hardy-Weinberg平衡状态(P＜0.05)。

Genetic Polymorphism of the Exon 2 of MHC-DQB Gene in Yunnan Humped Cattle

In this paper, the genetic polymorphism of the exon 2 of MHC-DQB gene was investigated by directly sequencing and PCR-RFLP in Yunnan humped cattle. Homology of the nucleotide acid sequences was analysis by DNAMAN software. The results showed that 17 alleles were found in this experiment,10 kinds of genotypes and 5 (A, B, C, D, E) alleles were found with enzyme Hae Ⅲ;22 kinds of genotypes and 11 (A, B, C, D, E, F, G, H, I, J, K) alleles were found with enzyme RsaⅠ;only one kind of genotype were found with enzyme TaqⅠ. Polymorphic sites were detected at base position 12, 25, 63, 96, 106, 126, 152, 156, 165 and 204. The results showed that there were same lengths (270 bp) of gene fragment in various species, but there was a nucleotide missing at position 224 and a nucleotide insertion at position 236 in Yunnan humped cattle. The homology between Yunnan humped cattle and human, swine, horse, sheep, Yellow cattle × Zebuand were 81.4%, 83.3%, 78.1%, 87.7% and 86.6%, respectively. The results of χ² test showed that the polymorphic loci of Hae Ⅲ and TaqⅠwere in Hardy-Weinberg equilibrium (P＞0.05), but the locus of RsaⅠ was not in equilibrium (P＜0.05).