广西仫佬族线粒体DNA高变Ⅰ区多态性分析

Genetic polymorphism of mitochondrial DNA hypervariable segment Ⅰ of Mulam ethnic group in Guangxi

目的探讨广西仫佬族人群线粒体DNA高变Ⅰ区的多态性特征,了解仫佬族群体的母系遗传结构。方法收集91例仫佬族无关男性个体的外周血样本,目标序列用引物L15947和R16488进行PCR扩增,用ABI3730测序仪正反向测序;计算多态性位点、核苷酸多态性、平均配对差异数目等多态性指标,以及仫佬族与各民族之间的遗传距离,ME法构建遗传进化树。结果与修正后的剑桥标准序列(rCRS)比对,91例样本的线粒体高变Ⅰ区序列共界定了74种单倍型,核苷酸多态性为0.0188±0.010,平均核苷酸差异为6.618±3.154;遗传距离显示仫佬族与南方各少数民族及南方汉族的亲缘关系较近,与北方汉族的亲缘关系较远,进化树中仫佬族与南方少数民族聚为一类。结论仫佬族在母系遗传上属于典型的南方侗傣族群,可能经历过群体扩张或选择效应;高变Ⅰ区序列具有较高的多态性,可用于法医个体识别、民族起源等方面的研究。

Objective To demonstrate the polymorphism of the mitochondrial DNA （mtDNA） hypervariable segment I （HVS I ） and to clearly understand the maternal genetic structure of Mulam ethnic group in Guangxi. Methods Venous blood samples from 91 unrelated Mulam individuals were collected. HVS I of mtDNA was amplified using primers L15947 and R16488. PCR amplicons were sequenced in both forward and reverse directions using the ABI 3730. Polymorphisms were scored relative to the revised Cambridge reference sequence （rCRS）. The number of polymorphic sites, number of haplotypes, the mean number of pairwise differences and genetic distances between populations were calculated. Polygenetic tree was drawn based on dA distance. Results MtDNA HVS I sequences showed high levels of diversity. Seventy-four haplotypes were identified among the 91 samples. The nucleotide diversity was 0. 0188 ± 0. 010 and the mean number of pairwise differences was 6. 618 ± 3. 154. Genetic distances between populations and the cluster map show that Mulam falls together with southern groups, but away from northern populations. Among southern populations, Mulam clusters were most closely with the Zhuang and Sui. Conclusion Mulam is a typical southern Kam-Tai population, and may experience population expansion or selection. MtDNA HVS- I reveals highly genetic diversities in Mulam, which may have potential use in population genetics and forensic practice.