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Nature：科学家破译猛犸象80%基因组
来源 新浪科技
Nature：科学家破译猛犸象80%基因组   美国科学家日前通过一团猛犸象的毛发，成功破译出这个史前庞然大物80%的基因组。尽管这是一团毫无光泽的毛发，却使科学家在复活猛犸象的道路上又向前迈进了一步。
   科学家通过已在西伯利亚长久冻结带冷冻数千年的猛犸象尸体提取的毛发样本，整理出这种史前巨兽的DNA。基因代码让科学家对猛犸象的进化过程有了新的了解，同时表明它们远比之前想象的更接近于现代象。这项发现还可以使研究人员搞清楚大象的遗传构造，复活灭绝已久的猛犸象。
   科学家利用从西伯利亚长久冻结带发现的两具猛犸象残骸上获取的DNA，实施了这种类似于科幻大片《侏罗纪公园》剧情的研究。美国科学家在*新一期科学杂志《自然》（Nature）上报告称，在这两具猛犸象尸体中，一具已在地下埋了2万年，另一具则至少埋了6万年。通过仔细分析它们的DNA，研究小组已经整理出80%的猛犸象基因组或遗传密码。
   这项研究表明，两头猛犸象关系十分紧密。另外分析还表明，600万年前，猛犸象和现代象走向了不同的进化路径，几乎与此同时，人类和黑猩猩也走上了与它们一样的进化道路。200万年前，猛犸象一分为二，一组在距今4.5万年前灭绝，另一组在距今1万年前*后一个冰河时期的末期从地球上消失。
   雄性猛犸象高约10英尺(约合3米)，雌性相对矮一些。它们的尖牙长而弯曲，腹部的毛发*长可达3英尺(约合0.9米)。迄今，科学家已在西伯利亚发现了大约40具猛犸象的尸体。实施*新研究的美国科学家之所以使用提取自猛犸象毛发的DNA，是因为相对于猛犸象尸体其他部位的DNA，它们保存得更为完好。
   一些研究人员一直建议使用冰冻猛犸象尸体的皮肤或毛发克隆猛犸象。领导这项研究的宾夕法尼亚州立大学教授史蒂芬•舒斯特(StephanSchuster)说：“从理论上讲，通过破译这个基因组，我们可以获取重要的信息，将来有**，只要将独特的猛犸象DNA序列融入现代象的基因组中，这些信息或能帮助其他研究人员复活猛犸象。”
    但是，西澳大利亚默多克大学古生物DNA实验室主任迈克尔•邦斯(MichaelBunce)博士给舒斯特教授泼了一瓢凉水。他说：“掌握某种生物的DNA代码并不意味着我们可以通过遗传手段实现重造灭绝生物体的美好愿望。”（创赛新闻中心canspecsci.com）

创赛推荐原始出处：
Nature，456, 387-390，Webb Miller，Stephan C. Schuster
Sequencing the nuclear genome of the extinct woolly mammoth
Webb Miller1, Daniela I. Drautz1, Aakrosh Ratan1, Barbara Pusey1,Ji Qi1, Arthur M. Lesk1, Lynn P. Tomsho1, Michael D. Packard1,Fangqing Zhao1, Andrei Sher2,9, Alexei Tikhonov3, Brian Raney4,Nick Patterson5, Kerstin Lindblad-Toh5, Eric S. Lander5, James R.Knight6, Gerard P. Irzyk6, Karin M. Fredrikson7, Timothy T.Harkins7, Sharon Sheridan7, Tom Pringle8 & Stephan C.Schuster1
1 Pennsylvania State University, Center for Comparative Genomicsand Bioinformatics, 310 Wartik Building, University Park,Pennsylvania 16802, USA
2 Severtsov Institute of Ecology and Evolution, Russian Academy ofSciences, 33 Leninsky Prospect, 119071 Moscow, Russia
3 Zoological Institute, Russian Academy of Sciences,Universitetskaya Naberezhnaya 1, 199034 Saint Petersburg,Russia
4 Center for Biomolecular Science and Engineering, University ofCalifornia, Santa Cruz, California 95064, USA
5 Broad Institute of MIT and Harvard, 7 Cambridge Center,Cambridge, Massachusetts 02142, USA
6 454 Life Sciences, 20 Commercial Street, Branford, Connecticut06405, USA
7 Roche Diagnostics Corporation, 9115 Hague Road, Indianapolis,Indiana 46250-0414, USA
8 Sperling Foundation, Eugene, Oregon 97405, USA
In 1994, two independent groups extracted DNA from severalPleistocene epoch mammoths and noted differences among individualspecimens1, 2. Subsequently, DNA sequences have been published fora number of extinct species. However, such ancient DNA is oftenfragmented and damaged3, and studies to date have typically focusedon short mitochondrial sequences, never yielding more than afraction of a per cent of any nuclear genome. Here we describe 4.17billion bases (Gb) of sequence from several mammoth specimens, 3.3billion (80%) of which are from the woolly mammoth (Mammuthusprimigenius) genome and thus comprise an extensive set ofgenome-wide sequence from an extinct species. Our data supportearlier reports4 that elephantid genomes exceed 4 Gb. The estimateddivergence rate between mammoth and African elephant is half ofthat between human and chimpanzee. The observed number ofnucleotide differences between two particular mammoths wasapproximately one-eighth of that between one of them and theAfrican elephant, corresponding to a separation between themammoths of 1.5–2.0 Myr. The estimated probability that orthologouselephant and mammoth amino acids differ is 0.002, corresponding toabout one residue per protein. Differences were discovered betweenmammoth and African elephant in amino-acid positions that areotherwise invariant over several billion years of combinedmammalian evolution. This study shows that nuclear genomesequencing of extinct species can reveal population differences notevident from the fossil record, and perhaps even discover geneticfactors that affect extinction.
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