【作者】 冯国英；

【导师】 胡盛平；

【作者基本信息】 汕头大学 ， 法医学， 2009， 硕士

【摘要】 背景:线粒体DNA(mitochondrial DNA,mtDNA)具有母系遗传、缺乏重组、突变率高等遗传特性,因此容易形成人群特异的遗传标记,是研究人类系统进化、人群迁移历史的一个很有用的遗传标记。由于线粒体DNA遵从严格的母系遗传方式,避免了混血影响,因而通过对线粒体差异的分析可以忠实再现人群的母系进化史。潮汕僻处我国的东南隅,广东省的最东端,与福建省毗邻,其地域包括今天的汕头、潮州、揭阳三个地级市。对应的潮汕人指居住于该区域并有自己独特方言和生活习惯的汉族民系。据历史记载,公元前214年之前,潮汕地区的主要先民是闽越族,秦汉之后,随着中原汉族后裔南迁并与当地原住民融合,潮汕人遂被逐渐同化为汉族。课题组前期曾采用HLA(Human leucocyte antigen)以及常染色体STR(Short tandem repeat)遗传标记在基因水平上对潮汕人群的人类学起源进行过研究。两种遗传标记的研究结果都显示潮汕汉族与南方汉族聚类并与闽南汉族亲缘关系最近,而与北方汉族的亲缘关系较远。STR研究的结果还显示在潮汕人群基因库中中原汉族的成分占主体,而南方原住民的成分较少。目的:从母系遗传的角度研究潮汕人群与中国其他人群之间的亲缘关系,进一步探讨潮汕人群母系基因库的遗传成分。方法:对潮汕汉族人群120例无关个体进行高变区(hypervariable segment 1 and hypervariable segment 2,HVS-1 and HVS-2)序列分析和COⅡ/tRNALys区段的9bp缺失检测,计算各种单倍群的频率。进一步收集其他人群的线粒体DNA第一高变区序列和单倍群频率数据用于人群比较。用聚类分析、主成分分析研究人群之间的亲缘关系;用融合分析计算北方汉族和南方原住民人群对潮汕人群母系基因库的贡献率大小。结果:潮汕人群的单倍型多样度(h)在1区和2区分别为0.992和0.942,核苷酸多样度(π)在1区和2区分别为0.02153和0.01049,9bp缺失频率为18.33%。在潮汕人群中,南方原住民的主要单倍群比北方汉族的主要单倍群所占的比例稍高一些。聚类分析和主成分分析的结果都显示潮汕人群与其他南方汉族人群聚类。在潮汕人群的母系基因库中南方原住民和北方汉族的成分基本上各占一半。此外,聚类分析和主成分分析的结果都显示中国人群南北分界明显。结论:线粒体DNA高变区在潮汕汉族人群中具有高度多态性;潮汕人群具有南方汉族人群的遗传特征;潮汕人群的母系遗传成分源于北方汉族和南方原住民;中国南北人群之间存在遗传差异。更多还原

【Abstract】 Background: Mitochondrial DNA (mtDNA) harbors a series of characteristics, such as matrilineal inheritance, absence of recombination, rapid rate of mutation, and high level of population-specific polymorphisms, which make it a very useful genetic marker for studying the human evolution and migration history of human ethnic groups. The matrilineal mode of inheritance enables researchers to trace related lineages back through time, highlighting the maternal ancestry of a population, without the confounding effects of biparental inheritance and recombination. Chaoshan, the eastern part of Guangdong Province, is a littoral located at the southeast of the Mainland China with its east abutting on Fujian. The whole region covers the areas of Shantou, Chaozhou, and Jieyang. People residing in this area speak in a unique dialect and have distinct lifestyle and are defined as Chaoshanese. According to history records, before 214 BC the main aboriginal living in the Chaoshan littoral was Minyue population. After the Qin and Han Dynasties, Han inhabitants of north-central China migrated into the Chaoshan area, gradually assimilated the preexisting aboriginals and eventually became the major population in the Chaoshan area. Our previous genetic study of Chaoshan population based on the Human leucocyte antigen (HLA) and autosomal Short tandem repeat (STR) markers revealed that Chaoshanese, while clustering in general with the southern China-related Han Chinese, had the highest affinity to the Mainland Minnanese, but separated distinctively from the northern Hans. Our study based on autosomal STR also showed that the gene pool of Chaoshan population consisted of a large majority of Central plain Han and a little Southern native origin.Objective: To investigate the genetic relationship between Chaoshan population and other Chinese populations from the perspective of maternal inheritance, and to analyze the genetic composition of Chaoshan population’s matrilineal gene pool.Method: Sequences of mtDNA hypervariable segment (HVS-1 and HVS-2) and the COⅡ/tRNALys intergenic deletion were investigated , and the mtDNA haplogroup frequencies were calculated in 120 unrelated Chaoshan individuals. Moreover, the mtDNA hypervariable segment region 1 sequence and haplogroup frequency data of other Chinese populations were collected and used for population comparison. Population relationships were investigated by phylogenetic analysis and principal component analysis. In addition, the admixture analysis was performed to estimate relative contribution of northern Hans and southern natives to Chaoshan population.Result: For Chaoshan population:haplotype diversity (h) was 0.992 for HVS-1 and 0.942 for HVS-2;nucleotide diversity (π) was 0.02153 for HVS-1 and 0.01049 for HVS-2;the 9-bp deletion frequency was 18.33%;the overall frequency of southern native dominant haplogroups was slightly higher than the overall frequency of northern Han dominant haplogroups. The results of phylogenetic analysis and principal component analysis revealed thatChaoshan population clustered with other southern Hans. In matrilineal gene pool of Chaoshan population, genetic composition of southern natives and northern Hans took up about 50% respectively. In addition, the results of phylogenetic analysis and principal component analysis also suggested that the distinction between north and south population in China was noticeable Conclusion: Mitochondrial DNA hypervariable segments in Chaoshan population had a high level of polymorphism. Chaoshan population had the genetic characteristics of southern Han and the matrilineal genetic composition of Chaoshan population consisted of both northern Han and southern native origin. There was significant genetic difference between Southern and Northern populations in China.更多还原