Genetic Analyses On Mitochondrial DNA From Tuoba Xianbei

Xianbei originated from"Eastern Hu", was another significant nomadic population succeeded by Xiongnu, which actually consisted of a federation of sizeable non-Han groups, occupied Han-Jin to Bei Chao dynasty. Tuoba Xianbei was a northern-most branch in Xianbei Alliance, and also was the first nomadic population that entered and held the Zhongyuan region. The regime, the Northern Wei dynasty (386 AD-534 AD) that was established by Tuoba Xianbei ruled the vast grassland in northern China and agricultural region in the Yellow River valley, and created a leading card of ethnic amalgamation. Further, they had made a contribution to the formation of pluralism and integration of the Chinese Nation. The early history of Tuoba Xianbei, however, was not yet clear because of the short historical materials, especially the history before the 4th century. Concerning the issues described in the following, the identity of views had not been achieved in Chinese history. There were many queries on the origin of Tuoba Xianbei. For example, eastern Xianbei and Tuoba Xianbei, which did originate earlier? Whether had Tuoba Xianbei joined in the Xianbei federation of Tanshihuai really? Could Xianbei be divided into eastern Xianbei and Tuoba Xianbei? Whether were the Tuoba Xianbeis the descendants of"Xianbei father and Hu mother"?"Xuji of Weishu"is a very important historical document on the Tuoba Xianbei history, but it recorded the history events in an oral statement. Together with the affects from political culture of Zhongyuan, there were many unintelligible issues in Weishu. Concerning the questions on the evolvement of Tuoba Xianbei, historians recognize the Tuoba Xianbei amalgamate with Han population. The genetic contribution to modern minorities from northern China, however, the identical viewpoint has not been obtained.Fortunately, during its 2 important southward migrations, Tuoba Xianbei left them behind many cemeteries of different period, which provide archaeologists and historians many ancient remains to clarify the early history of Tuoba Xianbei, and also provided lots of samples for aDNA study.Ancient DNA technique has made it possible to obtain the trace amount of DNA which still survived in archaeological remains. Scientists can research many great difficult problems from anthropology, such as human origin, evolution, migration and population developments without the limits from temporal and spatial obstacles.In order to analyze mitochondrial DNA (mtDNA) genetic diversity from Tuoba Xianbei ethnic group, the genetic affinities between Tuoba Xianbei and Xiongnu as well as modern Xibe, 22 thighbone samples of Tuoba Xianbei remains excavated from shangdu Dongdajing cemetery in Inner Mongolia (Dongdajing group) and 18 thighbone samples of Tuoba Xianbei remains excavated from Qahar Right Wing Middle banner Qilang Mountain cemetery in Inner Mongolia were used as researching objects of Tuoba Xianbei for DNA extracting, amplifying and sequencing, mainly the hypervariable segment I (HVS-I, 16039–16398) in mtDNA control region. At the same time, in order to analyze the genetic relationship between Tuoba Xianbei and Xibe, the mtDNAs from Xingjian Xibe population were analyzed using genetic methods.33 Tuoba Xianbei HVS-I sequences (17 from Dongdajing group, 16 from Qilang Mountain group) and 48 Xibe HVS-I sequences were obtained in our study. The editing of sequences was performed by Clustal X1.83. Fst genetic distances, Genetic diversity, the mean number of pairwise difference were computed by Arlequin 2000. The net genetic distances and phylogenetic tree were carried out using MEGA 3.0. To visualize the Fst distances among populations, the multidimensional scaling (MDS) analysis was performed by SPSS 12.0s. For comparison, the mtDNA data from 18 populations published were used. Ancient populations included 5 populations of Xiongng, Khitan, Jiangjungou population, Wanggu Tribe and Nianzi Mountain group etc; modern populations comprised 13 populations of Inner Mongolian, Outer Mongolian, Daur, Oroqen and Ewenki, Korean, Buryats, Evenks, Kazak, Uzbek, Turkey, Southern Han (Zhangjiang Han and Wuhan Han) and Northern Han (Qingdao Han and Fengcheng Han) etc.Genetic diversity analysis indicated that the haplotype diversity, the nucleotide diversity and the mean number of pairwise differences of Tuoba Xianbei were 0.974, 0.0186 and 6.16, respectively. According to Pakendorf et al. (2003), Kong et al. (2003) as well as Comas et al. (1998), the nucleotide diversity fell into those of the steppe populations (around 0.99) and the Siberian populations (0.93–0.95), and the nucleotide diversity of Tuoba Xianbei (0.0186) located between those of eastern Asian populations (from 0.0173 for Koreans to 0.0195 for Ainu). As for the haplogroup distribution and their status frequencies, Tuoba Xianbei presented haplogroup D, C, A, B and G mainly, and their frequencies were 39.13%D, 30.43%C, 19.39%A, 8.69%B and 6.25%G. Tuoba Xianbei presented evry high level haplogroup D and C (69.56%). Some haplogroups, such as D, G, C, and Z, were prevalent in these northern samples and the matrilineal genetic profile was consistent with the genetic pattern observed recently. Concerning the distribution of sharing sequences, Tuoba Xianbei sequences matched with the sequences distributed in Siberian (Northern Asia) and Northeast Asian populations, especially the populations of Oroqen, Ewenki and northern Mongolian, next in East Asian populations, including Northern Han, Korean and Japanese populations, which supported the conclusions obtained in skull study of Tuoba Xianbei.Population comparison indicated that Tuoba Xianbei presented a closer genetic affinity to Xiongnu among ancient populations, however the conclusion that Tuoba Xianbeis were the descendants of"Xianbei father and Hu mother"was not obtained. Tuoba Xianbei presented some similarities to Xiongnu in genetic diversity and genetic distance, but there were obvious differences in nucleotide diversity and haplogroup distribution frequencies between Tuoba Xianbei and Xiongnu. Relative to CRS, Xiongnu had high level G→A (13%), but Tuoba Xianbei didn't have it. According to Wallace et al.(1999), in Asia, the haplogroups include A, B, C, D, E, F and G etc. Tuoba Xianbei and Xiongnu all presented typical Asian haplogroups characteristics, but 3 out of 46 Xiongnu individuals belonged to haplogroup U of European type, and Tuoba Xianbei didn't have the U type.Among modern populations published, Tuoba Xianbei showed the closest affinity to Xibe and Oroqen, next to the populations of Outer Mongolian, Ewenki, Inner Mongolian, Northern Han, Korean and Evenks, again to the Central populations of Kazakh and Uzbek, and finally to Turkey people that live in juncture region of Eurasia. All the analyses of the genetic distance, phylogenetic analysis and the multidimensional scaling (MDS) analysis supported the concluton.There wee three creative achievements in this study: first, the paper was the first report on Tuoba Xianbei genetic diversity was studied using aDNA techniques, the result indicated the Tuoba Xianbei genetic diversity fell into the range of central Asian and North Asian populations; secondly, the affinities between Tuoba Xianbei and Xiongnu were clarified for the first time by molecular biology method, as the resulting, Tuoba Xianbei presented a closer genetic relationship to Xiongniu, but they were not the descendants of"Xianbei father and Hu mother"; and thirdly, the genetic affinities between Tuoba Xianbei and Xibe were analyzed using molecular biology method for the first time, the results implied that Tuoba Xianbei may be Xibe ancestor.The data information from Tuoba Xianbei mtDNA held the key to study the origin, evolution, and trace their gene contributions to modern relevant populations, and further understand the formation of pluralism and integration of the Chinese Nation.