论文标题:中国甘肃永昌骊靬人的父系遗传多态性研究
Studies on Paternal Genetics of Liqian People from Yongchang County of Gansu Province, China
论文作者
论文导师 王勋陵；安黎哲；谢小冬,论文学位 博士,论文专业 植物学
论文单位 兰州大学,点击次数 46,论文页数 67页File Size4772K
2007-04-01论文网 http://www.lw23.com/lunwen_323575107/
Y-STR; Y-SNP; population genetic; Liqian; ancient Roman mercenary
骊轩人是一群居住在中国，甘肃河西走廊东端永昌县的一些村庄里的特殊群体，其中一些人具有异于中国汉族的典型欧洲人的体质特征。近年来，骊轩人因为有争议的古罗马军团起源的假设而闻名于世。上世纪50年代牛津大学的汉学家Homer Dub认为，在卡莱战役(公元53年)以后，一些罗马士兵被帕提亚王国俘获，在中国定居，而且汉朝允许他们建立罗马风格的城市。几十年过去了，这个假设仍被激烈的争论着。因为缺乏直接的证据，父系遗传贡献就显得尤为重要。为了检验这个假说，本研究使用多聚酶链式反应(PCR)，限制性片段长度多态(PCR-RFLP)和变性高压液相色谱(dHPLC)的方法调查了由227个个体组成的四个中国西北人群的多于12个Y染色体单核苷酸多态位点，也同时使用Powerplex(?)Y系统分析了这四人群的12个Y-STR多态位点。与全球范围内发表的各相关人群Y-DNA数据比较，得到如下主要研究结果： 1．在87个骊轩男性个体中，共检出11个Y-SNP单倍群和75个Y-STR单倍型。在单倍群水平上，因其高频的单一单倍群O-M122(71.3％)的存在，骊轩人群表现出较低的遗传多样性值(0.47)。使用进化速率较快的12个Y-STR所得的遗传多样性值高于0.98。在本研究中，77％的骊轩Y染色体属于东亚特有的单倍群O-M175，而且单倍群O-M175的频率高于大多数中国北方的其他人群。 2．主成分分析(PC)和多维尺度(MDS)分析表明骊轩人和中国人群有较近的遗传关系，尤其是和汉族的遗传关系最近，而他们与中亚和西欧亚人群表现出较远的遗传关系。基于这两种分析，也可以得到一个结论：与Y-STR相比，尽管双等位多态位点有偏见，但是基于Y-SNPs的主成分分析和基于Y-STRs的多维尺度分析的结果是一致的。系统进化分析进一步肯定了骊轩人和汉族的遗传亲近性。 3．根据PC和MDS分析筛选出与骊轩遗传关系最近的古老人群：汉族和蒙古族。这两个人群假定为骊轩人的祖先人群，而骊轩人则被认为是这两个人群的杂合人群而进行混合度的计算，结果表明：汉族对骊轩人的父系遗传贡献高达70％之多，蒙古族对骊轩的遗传贡献相对较小。 4．在Median-joining network分析中发现，因曾有人认为有共同的族源而被称为兄弟人群的骊轩和裕固族表现出一定的遗传差异。 5．骊轩人与临近的人群表现出较近的遗传关系。这一事实在Mantel test分析中得到进一步的证实，Mantel检验表明与骊轩遗传关系较近的人群两两遗传距离和地理距离呈线性相关。 6．在统计学上，骊轩人和北方汉族之间的遗传差异不显著，和其余欧亚人群均表现出显著的遗传差异。 7．在与YHRD数据库中世界范围的数据比对发现，由9个位点组成的大多数骊轩单倍型与东亚和南亚单倍型相匹配，仅有2个单倍型和欧洲单倍型相同，但这两个单倍型属于东亚特异的单倍群O-M122。这一矛盾的结果可能源于快速进化Y-STR的回复突变。 总之，根据骊轩父系遗传变异的研究结果，不支持罗马军团起源说。当前的骊轩人更具一个汉民族亚人群的特征。本论文为骊轩的父系遗传组成提供了证据，也丰富了人类基因数据库。所选取的12个Y-STR多态位点组成的单倍型具有极高的分辨力，是亲子鉴定和个体识别的有利工具。
Liqian people, officially recognized as Han Chinese by P. R. China, live in some small village located in Yongchang County of Gansu province, China. Many of them have light colored hair and Caucasian features, which are sharply different from Han Chinese and most ethnic minorities. Recent years, Liqian people were well known to all with controversial hypothesis of ancient Roman mercenary origin. In 1955, Homer H. Dubs proposed that some Roman soldiers captured by the Parthians after Crassus"s defeat at Carrhae in 53 B.C. were eventually hired as mercenaries by a Hun warlord in the western frontier past the boundaries of the Han Empire and were captured by the Chinese and allowed to form their own city, based on the Roman model. The hypothesis has been adopted by some scholars. It was, however, disputed by many historians. Several decades passed, the hypothesis remains hotly debated. No direct evidence, paternal genetic contribution seems particular necessary. To test this hypothesis, we surveyed more than 12 Y chromosome binary polymorphisms by use of PCR (polymerase chain reaction), PCR-RFLP (restriction fragment length polymorphism), DHPLC (Denaturing High Performance Liquid Chromatography) methods and 12 short tandem repeat (Y-STRs) loci by using Powerplex~(?) Y system for 227 male individuals representing four Chinese populations: Liqians, Yugurs, Uygur and Tibetans. In comparison with worldwide populations, the following results were obtained. 1. Eleven Y-SNP haplogroup and 75 Y-STR haplotype were observed for 87 unrelated Liqian males. At the haplogroup level, the Liqians presented low genetic diversity with a single highest frequent haplogroup O3-M122 (71.3%). When 12 fast-evolving Y-STRs were used, the genetic diversity of Liqians is high than 0.98. In present study, 77% Liqian Y chromosomes were restricted to East Asia. It is unexpected that the frequency of Haplogroup O-M175, an East Asian-specific haplogoup, is relatively higher in Liqian people than that in most populations in North China. 2. Principal Component (PC) based on Y-SNPs and multidimensional scaling (MDS) analysis on basis of Y-STRs suggests that the Liqians is closely related to Chinese populations, especially Han Chinese populations, whereas greatly deviate from Central Asian and West Eurasian populations. The positions of populations within some clusters correspond well to their predefined assignments to specific regional groups. One conclusion can also be drawn from these analyses: despite the ascertainment bias in the binary markers, PC result based on Y-SNPs is consistent with MDS result on basis of Y-STRs. In addition, further phylogenetic analysis confirmed the genetic affinity between Liqian and Han Chinese populations. 3. By PC and MDS analysis, we found two old populations: Han Chinese and Mongolians, which showed close genetic relationship to Liqians. In subsequent admixture analysis, the two populations were assumed to be parental populations of Liqians, and the Liqians is regarded as hybride population. Admixture proportional analysis suggested that the genetic contribution from Han Chinese amount to 78% in Liqians. 4. The Liqians and the Yugurs, regarded as kindred populations with common origins, present underlying genetic difference in Median-joining network and admixture proportional analysis. 5. Liqian population show close affinities to its geographic neighbors. This is confirmed in Mantel test (r=0.646, P =0.003), which show a strong and highly significant partial correlation between genetics and geography among population mentioned in our study. 6. Statistically, the Liqian showed non-significant genetic difference to Han Chinese in North China, and significant genetic difference to other Eurasian populations. 7. When we compare Liqian minimal haplotypes (9 loci "minimal haplotype") with worldwide data in YHRD, most Liqian haplotypes were found in East Asia and South Asia. Only two matches were found in Europe, but they belonged to East Asia-specific Haplogroup O-M122. The incompatible result probably originated from recurrent mutation of fast-evloving Y-STRs. Overall, Roman mercenary origin could not be accepted as a history truth according to paternal genetic variation, and the current Liqian population is more likely to be a subgroup of Chinese majority Han. Our studies provided genetic evidence for the origin of the Liqian people, and inriched to human genetic database. The 12 Y-STR polymorphism markers are highly discriminating in the Chinese Liqian population, and they may be powerful for paternity testing and personal identification.
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