中國科學家破解遺傳基因謎團 東亞人群起源非洲

【中新社昆明十九日電】中國科學院昆明動物研究所今日宣佈,該所孔慶鵬研究員與張亞平院士課題組以母系遺傳的線粒體DNA(mtDNA)為遺傳標記的研究取得進展,通過收集分析了採自八十四個中國人群六千餘份樣本的mtDNA序列,結果顯示迄今甄別出來的mtDNA事實上均源自非洲起源的建群類型M或N,沒有發現可能追溯至古人類的母系遺傳組份。“這從mtDNA全基因組角度支持了東亞人群起源於非洲的假說。”孔慶鵬說。
    據介紹,來自體質人類學、語言學和經典遺傳學的證據認為,東亞人群存在一個以長江為界的古老而明顯的南北分界線。然而,孔慶鵬等科學家基於多種遺傳標記對東亞人群進行系統研究後發現,南方群體和北方群體間雖然存在一定的遺傳差異,但這種差異並不是截然的。來自於臨近地理區域的人群在主成份分析圖上表現出相近的關係,因而他們推測地理距離隔離對東亞人群的遺傳結構具有重要影響。群體間的地理距離隔離和南北方群體間群體擴張歷史的差異可能是導致南北群體遺傳差異的重要原因。
    孔慶鵬表示,研究中新鑒別的基部類群很可能代表了最初進入東亞南部的現代人群祖先的母系遺存,而非來自鄰近地區(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佈在中國南部,提示中國南部很可能就是現代人類祖先進入東亞後的主要聚集及分化地。http://www.macaodaily.com/html/2010-08/20/content_500117.htm
  
           
中國首次在人工環境下成功繁育帝企鵝幼仔。圖為帝企鵝媽媽 在大連海洋公園極地館內給小帝企鵝餵食。(新華社)http://www.macaodaily.com/html/2010-08/20/content_500118.htm
http://mbe.oxfordjournals.org/cgi/content/abstract/msq219v1
Received for publication March 4, 2010. Accepted for publication August 10, 2010.

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.
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