(封面图片:Green等科学家首次发表了一个尼安德特人线粒体基因组的完整测序结果。图片提供:Steven W. Marcus)
尽管科学家相信尼安德特人是最接近现代人类的原始人种,但是关于他们与现代人类之间的精确关系却一直存在争论。自从1997年尼安德特人分子基因数据首次公布以来,多种分析结果显示其线粒体DNA与现代人存在差异,由于线粒体DNA基因组是母系遗传,并不会受到重组的影响,因此这些结果意味着尼安德特人对现代人类的线粒体DNA基因库并没有贡献。
最近高通量454测序技术被广泛应用于分析古代DNA样本,这些方法为复原古代DNA提供了可能。454测序技术的最大优势在于能获得大量的测序数据,从而能应用于基因组尺度的古代DNA测序项目。454测序技术特别适合于线粒体基因组,因为其数据较少,而且在细胞中广泛存在。在2008年8月8日出版的《细胞》(Cell)上,来自德国、美国、克罗地亚和芬兰的科学家发表了他们的最新研究结果,通过454测序技术,科学家得到了一个尼安德特个体的完整线粒体DNA基因组序列。
通过对1980年从克罗地亚的Vindija Cave出土的尼安德特人骨样本的测序,科学家从0.3克骨骼中得到了4.8Gb的DNA数据,并从中获得了8341线粒体DNA序列。这一尼安德特人个体大约生活在距今38000年前。在此之前,尽管科学家曾经得到过该骨骼样本的线粒体DNA的HVRI序列结果,但是获得完整的线粒体DNA序列这还是首次,这一结果将有助于科学家研究现代人类和尼安德特人线粒体DNA之间在进化上的关系。
文章中科学家还表示,此次获得的完整尼安德特人线粒体DNA序列进一步确认了之前对于尼安德特人的推测。首先,结果确认了其线粒体DNA与现代人的差别。其次,研究人员发现尼安德特人线粒体DNA大约在660000年之前与现代人类线粒体DNA世系发生进化上的分离。(生物谷Bioon.com)
生物谷推荐原始出处:
Cell,Vol 134, 416-426, 08 August 2008,Richard E. Green, Svante Pääbo
A Complete Neandertal Mitochondrial Genome Sequence Determined by High-Throughput Sequencing
Richard E. Green,1, Anna-Sapfo Malaspinas,2 Johannes Krause,1 Adrian W. Briggs,1 Philip L.F. Johnson,3 Caroline Uhler,4 Matthias Meyer,1 Jeffrey M. Good,1 Tomislav Maricic,1 Udo Stenzel,1 Kay Prüfer,1 Michael Siebauer,1 Hernán A. Burbano,1 Michael Ronan,5 Jonathan M. Rothberg,6 Michael Egholm,5 Pavao Rudan,7 Dejana Brajković,8 Željko Kućan,7 Ivan Gušić,7 Mårten Wikström,9 Liisa Laakkonen,10 Janet Kelso,1 Montgomery Slatkin,2 and Svante Pääbo1
1 Max-Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany
2 Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
3 Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
4 Department of Statistics, University of California, Berkeley, CA 94720, USA
5 454 Life Sciences, Branford, CT 06405, USA
6 The Rothberg Institute for Childhood Diseases, Guilford, CT 06437, USA
7 Croatian Academy of Sciences and Arts, Zrinski trg 11, HR-10000 Zagreb, Croatia
8 Croatian Academy of Sciences and Arts, Institute for Quaternary Paleontology and Geology, Ante Kovačića 5, HR-10000 Zagreb, Croatia
9 Helsinki Bioenergentics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, FIN-00014 Helsinki, Finland
10 Division of Biochemistry, Department of Biological and Environmental Sciences, Faculty of Biosciences, University of Helsinki, FIN-00014 Helsinki, Finland
Summary
A complete mitochondrial (mt) genome sequence was reconstructed from a 38,000 year-old Neandertal individual with 8341 mtDNA sequences identified among 4.8 Gb of DNA generated from ∼0.3 g of bone. Analysis of the assembled sequence unequivocally establishes that the Neandertal mtDNA falls outside the variation of extant human mtDNAs, and allows an estimate of the divergence date between the two mtDNA lineages of 660,000 ± 140,000 years. Of the 13 proteins encoded in the mtDNA, subunit 2 of cytochrome c oxidase of the mitochondrial electron transport chain has experienced the largest number of amino acid substitutions in human ancestors since the separation from Neandertals. There is evidence that purifying selection in the Neandertal mtDNA was reduced compared with other primate lineages, suggesting that the effective population size of Neandertals was small.