贵州务川黑牛mtDNA Cytb基因遗传多样性研究*

 务川黑牛是贵州省新近发现的独特地方品种，其起源和系统地位尚存争议。测定了22个务川黑牛的Cyt b基因全序列，结合已报道的中国9个黄牛品种17个个体的Cyt b基因全序列进行分析，结果显示：务川黑牛的Cytb基因全长1140 bp，共检测到21个核苷酸多态位点。碱基A+T平均含量为567%，显著高于G+C平均含量43.4%，第3密码子表现出较强的碱基组成偏倚。定义了8种单倍型且突变类型仅存在转换，表明务川黑牛的Cyt b基因的遗传多态性较为丰富。邻接法(NJ）构建的分子系统树表明，务川黑牛有2个母系起源即普通牛起源和瘤牛起源。

Study on Genetic Diversity of Mitochondrial DNA Cyt b Gene in Wuchuan Black Cattle of Guizhou

Wuchuan Black cattle, a newly discovered species, are unique in Guizhou Province. Its origin and systematics are remaining controversial today. The complete sequences of mitochondrial DNA cytochrome b (Cyt b)gene from 22 Wuchuan black cattle were cloned and analyzed based on the referenced bovine sequence data. The Cytb gene of Wuchuan black cattle was 1140bp in length with 21 polymorphic sites. The average percentage of A+T (56.7%) was higher than that of G+C (43.4%) and a conspicuous base composition bias was found in the third codon. These polymorphic sites were all transitions and divided the 22 Wuchuan black cattle individuals into 8 haplotypes, which suggested that the Cyt b gene polymorphism was abundant in Wuchuan Black cattle. The results indicated that Wuchuan black cattle were probably originated from two progenitorsBos taurusand Bos indicus.