隨著大量線粒體DNA（mtDNA）全基因組信息的積累，東亞人群的母系遺傳結(jié)構(gòu)已經(jīng)得到較為清晰的認(rèn)識(shí),。然而，研究中仍發(fā)現(xiàn)有一些mtDNA類型無(wú)法識(shí)別,，雖然這些未定類型的分布頻率很低,，但其系統(tǒng)發(fā)育地位究竟如何迄今仍不得而知。與此同時(shí),，由于東亞具有豐富且較為連續(xù)的古人類（the archaic hominid）化石記錄,，該地區(qū)人群因而被認(rèn)為可能為獨(dú)立起源或存在來(lái)自古人類的遺傳貢獻(xiàn),。雖然該觀點(diǎn)被來(lái)自Y染色體的研究工作所否定,，但不同的聲音認(rèn)為,，Y染色體研究?jī)H能從父系角度排除該可能性，并不能否定存在母系貢獻(xiàn)的可能,。顯然,，如果現(xiàn)代東亞人群中確實(shí)存在源自古人類的母系遺傳貢獻(xiàn)，那么這些類型則很可能分布于那些低頻且迄今無(wú)法確定其系統(tǒng)發(fā)育地位的mtDNA類型之中,。
為了解決這個(gè)問題，中科院昆明動(dòng)物研究所孔慶鵬研究員與張亞平院士課題組合作對(duì)東亞人群進(jìn)行了大規(guī)模研究,。通過收集分析了采自84個(gè)中國(guó)人群6000余份樣本的mtDNA序列,，從中甄別出近200個(gè)未定類型，采用mtDNA全基因組測(cè)序等手段確定所有未定類型的系統(tǒng)發(fā)育地位,，并將結(jié)果應(yīng)用于其它已發(fā)表的5000余份東亞人群mtDNA序列數(shù)據(jù),。研究結(jié)果揭示，迄今甄別出來(lái)的mtDNA未定類型事實(shí)上均源自非洲起源的建群類型M或N,，沒有發(fā)現(xiàn)可能追溯至古人類的母系遺傳組份,。進(jìn)一步分析還提示，研究中新鑒別的基部類群很可能代表了最初進(jìn)入東亞南部的現(xiàn)代人群祖先的母系遺存,，而非來(lái)自鄰近地區(qū)（例如東南亞）的近期基因流。考慮到這些基部類群主要集中分布在中國(guó)南部,，提示該區(qū)域很可能是現(xiàn)代人類祖先進(jìn)入東亞后的主要聚集及分化地,。該項(xiàng)研究工作是雙方繼中國(guó)藏族的起源等研究之后又一共同完成的研究成果，目前已在線發(fā)表在國(guó)際重要期刊《分子生物與進(jìn)化》（Mol Biol Evol）上,。（生物谷Bioon.com）
生物谷推薦原文出處：
Molecular Biology and Evolution, doi:10.1093/molbev/msq219
Large-scale mtDNA screening reveals a surprising matrilineal complexity in East Asia and its implications to the peopling of the region
Qing-Peng Kong1,2,*, Chang Sun1, Hua-Wei Wang3, Mian Zhao1,2, Wen-Zhi Wang1,2, Li Zhong3, Xiao-Dan Hao1,2, Hui Pan1,2, Sha-Yan Wang4, Yao-Ting Cheng1,2, Chun-Ling Zhu1, Shi-Fang Wu1, Li-Na Liu1, Jie-Qiong Jin1, Yong-Gang Yao5 and Ya-Ping Zhang1,2,3,*
1 State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
2 KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming 650223, China
3 Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China
4 Shenzhen People's Hospital, Clinical Medical College of Jinan University, Shenzhen 518020, China
5 Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
In order to achieve a thorough coverage of the basal lineages in the Chinese matrilineal pool, we have sequenced the mitochondrial DNA (mtDNA) control region and partial coding-region segments of 6,093 mtDNAs sampled from 84 populations across China. By comparing with the available complete mtDNA sequences, 194 of those mtDNAs could not be firmly assigned into the available haplogroups. Completely sequencing 51 representatives selected from these unclassified mtDNAs identified a number of novel lineages, including five novel basal haplogroups that directly emanate from the Eurasian founder nodes (M and N). No matrilineal contribution from the archaic hominid was observed. Subsequent analyses suggested that these newly identified basal lineages likely represent the genetic relics of modern humans initially peopling East Asia, instead of being the results of gene flow from the neighboring regions. The observation that most of the newly recognized mtDNA lineages have already differentiated and show the highest genetic diversity in southern China provided additional evidence in support of the Southern-Route peopling hypothesis of East Asians. Specifically, the enrichment of most of the basal lineages in southern China and their rather ancient ages in Late Pleistocene further suggested that this region was likely the genetic reservoir of modern humans after they entered East Asia.
