4个绵羊品种MHC-DRB3基因外显子2的多态性分析

采用PCR-RFLP方法分析4个绵羊品种（阿勒泰羊、中国美利奴肉用多胎品系、湖羊和陶塞特羊）MHC-DRB3基因第2外显子的多态性，并进行聚类分析以及基因杂合度和多态信息含量的计算。结果表明：在绵羊MHC-DRB3基因第2外显子第122、154、168、220和241 bp碱基处表现出多态性；χ2适合性检验结果表明，4个绵羊群体MHC-DRB3基因的第2外显子的PstⅠ酶切位点达到了Hardy-Weinberg平衡状态，TaqⅠ和HaeⅢ酶切位点多态性均未达到Hardy-Weinberg平衡状态；4个绵羊群体基因杂合度和多态信息含量值分别在0.693～0.774和0.662～0.738之间，表明4个绵羊品种具有丰富的遗传多样性；聚类结果表明，中国美利奴肉用多胎羊和湖羊亲缘关系最近，阿勒泰羊和陶塞特羊关系较远，与实际选育过程一致，MHC-DRB3多态性可作为绵羊育种标记进一步研究。

Polymorphisms of Exon 2 of MHC-DRB3 Gene in Four Sheep Breeds

In this study, the exon 2 of MHC-DRB3 gene was amplified by PCR and a uniform fragment of 285 bp was obtained in four sheep breeds(Aletai sheep, China merino sheep and hu sheep, Dorset sheep).The 285 bp PCR product was digested with restriction endomuclease PstⅠ,TaqⅠand HaeⅢ, and genetic polymorphism were investigated by PCR RFLP. The results indicated that it had polymorphisms in the 122th, 154th, 168th, 220th and the 237th.The χ2 tests showed that PstⅠrestriction enzyme sites were Hardy Weinberg equilibrium in all sheep population, TaqⅠand HaeⅢ restriction enzyme sites were not Hardy-Weinberg equilibrium in four sheep population. The Gene heterozygosity is 0.693~0.774 and polymorphism information content is 0.662~0.738 in four sheep breeds, the results showed that the genetic diversity of four sheep breeds are rich; Clustering analysis showed that China merino sheep had the closest genetic relationship with hu sheep, further with Aletai sheep and Dorset sheep,it is the same with breed selection,and can do further reacher on the Polymorphisms of MHC-DRB3 Gene as the sheep breeding marker.