來自紐約大學(xué)牙科學(xué)院（NYUCD）的一組科學(xué)家最近發(fā)現(xiàn),，一種口腔細菌有力的支持了現(xiàn)代人類最早是從非洲向亞洲遷移的觀點,。
這一小組是由NYUCD的Page Caufield教授領(lǐng)導(dǎo)的,，他們發(fā)現(xiàn)這種和齲齒有關(guān)的細菌——Streptoccocus mutans隨著人類宿主以一條非常清晰的線索進化,，并且能追溯到一個大約生活在100000到200000年之前的非洲的共同原始祖先,。
該細菌能從母親傳遞給她們的嬰兒,，然后大約在嬰兒2歲時首次出現(xiàn)在口腔中,。Caufield的這些發(fā)現(xiàn)發(fā)表在了刊物《Journal of Bacteriology》上,。在小組的研究過程中，Caufield利用了DNA指紋以及其它的很多生物標記分子等,?？茖W(xué)家曾經(jīng)利用這些技術(shù)來追溯人類的進化，并尋找到了一個共同的人類非洲祖先——ancestral Eve,。
Caufield表示：“隨著人類在世界范圍內(nèi)的遷移,，并且逐漸進化為各種不同的人種，這一口腔細菌也隨著它們的人類宿主共同進化,。”Caufield在過去的20年間從六大洲的人群中收集了超過600分樣本,，他的分析主要集中在中國、日本,、非洲,、非裔美國人、美國的西班牙人和高加索人,、瑞典,、澳洲、亞馬遜印第安人等中,。
Caufield說：“追蹤細菌比交容易,，因為它們用分裂進行繁殖。通過DNA分析,，我們重建了進化樹,，結(jié)果顯示其發(fā)源在非洲，然后主要的一個分支遷移到了亞洲,。接著從亞洲向歐洲延伸出一個分支,，進化成了現(xiàn)代高加索人種的一支。”下一步Caufield將分析細菌從亞洲向北美及南美共同進化的情況,。
譯自：physorg.com
部分英文原文：
Journal of Bacteriology, February 2007, p. 1238-1243, Vol. 189, No. 4
0021-9193/07/$08.00+0 doi:10.1128/JB.01183-06
Population Structure of Plasmid-Containing Strains of Streptococcus mutans, a Member of the Human Indigenous Biota
Page W. Caufield,1,2* Deepak Saxena,1 David Fitch,3 and Yihong Li1
College of Dentistry,1 School of Medicine,2 Department of Biology, New York University, New York, New York3
Received 31 July 2006/ Accepted 25 October 2006
There are suggestions that the phylogeny of Streptococcus mutans, a member of the human indigenous biota that is transmitted mostly mother to child, might parallel the evolutionary history of its human host. The relatedness and phylogeny of plasmid-containing strains of S. mutans were examined based on chromosomal DNA fingerprints (CDF), a hypervariable region (HVR) of a 5.6-kb plasmid, the rRNA gene intergenic spacer region (IGSR), serotypes, and the genotypes of mutacin I and II. Plasmid-containing strains were studied because their genetic diversity was twice as great as that of plasmid-free strains. The CDF of S. mutans from unrelated human hosts were unique, except those from Caucasians, which were essentially identical. The evolutionary history of the IGSR, with or without the serotype and mutacin characters, clearly delineated an Asian clade. Also, a continuous association with mutacin II could be reconstructed through an evolutionary lineage with the IGSR, but not for serotype e. DNA sequences from the HVR of the plasmid produced a well-resolved phylogeny that differed from the chromosomal phylogeny, indicating that the horizontal transfer of the plasmid may have occurred multiple times. The plasmid phylogeny was more congruent with serotype e than with mutacin II evolution, suggesting a possible functional correlation. Thus, the history of this three-tiered relationship between human, bacterium, and plasmid supported both coevolution and independent evolution.
* Corresponding author. Mailing address: New York University College of Dentistry, 345 East 24th Street, New York, NY 10010. Phone: (212) 998-9603. Fax: (212) 995-3994. E-mail:[email protected] .
Published ahead of print on 3 November 2006.
