西藏小型猪的线粒体DNA控制区分析

目的研究西藏小型猪的遗传标记以及与其他国内地方猪的亲缘关系。方法扩增102头西藏小型猪以及16头巴马小型猪、17头贵州香猪的线粒体DNA控制区,测序并与国内其他猪进行比较。结果西藏小型猪线粒体DNAD-loop区分三个区域。串联重复序列区处于中间位置,包含有15～29个10 bp的重复片段,分为A、B两种类型。D-loop 3′端340 bp,与国内其他猪的序列相同比较保守;5′端704 bp,共有22个变异位点。由22个变异位点中归纳出25个单倍型,其中有两种主要的单倍型,分别占34.4%和36.6%。根据三个转换位点：305、500、691,将西藏小型猪分成了两组,几乎与串联重复序列所分的A、B两组类型相对应。与西藏小型猪相比,巴马小型猪和贵州香猪D-loop 5′端变异位点较少,分别只有4种和2种单倍型,串联重复区也只有一个类型。结论西藏小型猪可能有两个母系祖先并且与我国西南地区的品种猪有较近的亲缘关系;不同的串联重复片段类型和5′端的变异位点可以联合组建西藏小型猪的遗传标记。

Analysis of Mitochondrial DNA D-Loop Region Sequences in Tibet Mini-Pigs

Objective To analyze the mitochondrial DNA D-loop region sequences of Tibet mini-pigs, and to explore their cytoplasmic DNA markers which can be used to identify them and the phylogenetic relationship between Tibet mini-pigs and other local pig breeds in China. Method MtDNA D-loop region in 102 Tibet mini-pigs, 16 Bama miniature pigs and 17 Guizhou xiang pigs were amplified and sequenced, followed by comparison with the data of other Chinese domestic pigs. Result The results showed that the D-loop region of Tibet mini-pigs was divided into three areas. The tandem repeat sequence including 15 - 29 10 bp repeat motif and located in the middle of mtDNA D-loop region consisted of type A and type B. The 340 bp sequence at 3＇-end of the D-loop, which was very conservative, exhibited particularly high homology with the same region in other domestic pigs. The 704 bp sequence at 5＇-end of the D-loop had 22 polymorphic sites. 22 polymorphic sites deduced 25 haplotypes, among which the percentage of two major haplotypes reached 34.4% and 36.6% , respectively. Based on three transform sites （305, 500, 691）, Tibet mini-pigs could be divided into two groups, approximately corresponding to type A and B of tandem repeat sequence. Compared with Tibet mini-pigs, Bama miniature pigs and Guizhou xiang pigs bad four and two haplotypes, respectively, and had type A of tandem repeat sequence. Conclusion It is inferred that Tibet mini-pigs originated from two maternal ancestors and have close relative relationship with local pigs in southwest China. The repeating motif in combination with the variable sites at the 5＇-end of mtDNA D-loop region can be used as a genetic marker to identify Tibet mini-pigs.