秦川牛mtDNA cyt b基因序列多态性分析

Analysis of mtDNA Cyt b Gene Sequence Polymorphism in Qinchuan Cattle

对我国秦川牛6个个体mtDNAcytb基因1140bp序列进行了分析。结果表明：6头秦川牛的cytb基因序列中，共检测到核苷酸多态位点19个。cytb基因全序列突变类型只有转換。6个个体具有4种单倍型。以欧洲牛mtDNAcytb基因全序列为标准，其中单倍型Ⅰ、单倍型Ⅱ、单倍型Ⅲ的核苷酸变异率较低，都为0．071%，而单倍型Ⅳ的核苷酸变异率较高，为1．21%。应用MEGA软件中UPGMA法构建6头秦川牛的分子进化树，结果表明秦川牛有2个母系起源即普通牛起源(单倍型Ⅰ、单倍型Ⅱ和单倍型Ⅲ)和瘤牛起源(单倍型Ⅳ)，但是本研究发现作为中原牛之一的秦川牛受普通牛的影响比较大。

The complete sequences of mitochondrial Cyt b gene from six Qinchuan cattle were analyzed. Comparison of these sequences revealed 19 polymorphic sites which were all transitions. Four haplotypes were defined from 19 variations. With the complete sequence of mtDNA cyt b for European cattle as a control, lower frequency of nucleotide variation was observed in haplotype No. 1, No. 2 and No. 3, respectively, but higher frequency was found in No. 4. Phylogenetic tree of six Qinchuan cattle was constructed using UPGMA in MEGA. The results indicated that Qinchuan cattle were probably originated from two progenitors; Bos taurus and Bos indicus. Furthermore, Bos taurus had greater influence to Qinchuan cattle than Bos indicus did.