美国科学家2月11日在《自然》杂志上发表论文称，一次目前所知甚少的大规模爆发的基因变异将人从大猩猩中分离出来，也将非洲黑猩猩、大猩猩和猩猩从猴子中分离。
华盛顿大学遗传学家埃文·埃什勒和同事发现，大约1000万年前，在大猩猩从其它猩猩和猴子中分离出来之前，它们的DNA开始出现爆炸性的变化——并非传统的变异，而是被称为复制数量变异的变化，这些DNA序列的变化可能有助于解释什么使人类和其它猿类相区别。
埃什勒也是霍华德·休斯医学会的研究人员，他的团队分析了人、黑猩猩、猩猩以及猕猴的这个DNA。他们认为，一些在进化树上不同距离的物种可以被看作时间机器，以追踪几千年来所发生的变化。
他们发现，就整个序列来说，人类和非洲黑猩猩非常接近，主要的区别在于复制数量的变化，也就是同一个遗传序列重复的次数不同，删除的内容不同等。埃什勒说，在人类中，这些变异同艾滋病和孤独症等疾病相关，这些变异也构成了物种之间的差异的基础。
分析表明，在灵长类的分支变成非洲大猩猩和人类的过程中，这些复制的数量开始增加，同时，越来越多传统的基因变异开始缓慢减少。他们称，尤其是人类和非洲黑猩猩，这些序列的额外复制格外多。
埃什勒说：“在基因组突然被重新排列和发生变化的地方，会产生巨大的变化。这些基因可能对语言或某些认知能力很重要，但还需要做很多工作。”（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 457, 877-881 (12 February 2009) | doi:10.1038/nature07744
A burst of segmental duplications in the genome of the African great ape ancestor
Tomas Marques-Bonet1,2, Jeffrey M. Kidd1, Mario Ventura3, Tina A. Graves4, Ze Cheng1, LaDeana W. Hillier4, Zhaoshi Jiang1, Carl Baker1, Ray Malfavon-Borja1, Lucinda A. Fulton4, Can Alkan1, Gozde Aksay1, Santhosh Girirajan1, Priscillia Siswara1, Lin Chen1, Maria Francesca Cardone3, Arcadi Navarro2,5, Elaine R. Mardis4, Richard K. Wilson4 & Evan E. Eichler1
1 Department of Genome Sciences, University of Washington and the Howard Hughes Medical Institute, Seattle, Washington 98195, USA
2 Institut de Biologia Evolutiva (UPF-CSIC), 08003 Barcelona, Catalonia, Spain
3 Sezione di Genetica-Dipartimento di Anatomia Patologica e Genetica, University of Bari, 70125 Bari, Italy
4 Genome Sequencing Center, Washington University School of Medicine, St Louis, Missouri 63108, USA
5 Institució Catalana de Recerca i Estudis Avan?ats (ICREA) and Instituto Nacional de Bioinformática (INB), Dr. Aiguader 88, 08003 Barcelona, Spain
It is generally accepted that the extent of phenotypic change between human and great apes is dissonant with the rate of molecular change1. Between these two groups, proteins are virtually identical1, 2, cytogenetically there are few rearrangements that distinguish ape–human chromosomes3, and rates of single-base-pair change4, 5, 6, 7 and retrotransposon activity8, 9, 10 have slowed particularly within hominid lineages when compared to rodents or monkeys. Studies of gene family evolution indicate that gene loss and gain are enriched within the primate lineage11, 12. Here, we perform a systematic analysis of duplication content of four primate genomes (macaque, orang-utan, chimpanzee and human) in an effort to understand the pattern and rates of genomic duplication during hominid evolution. We find that the ancestral branch leading to human and African great apes shows the most significant increase in duplication activity both in terms of base pairs and in terms of events. This duplication acceleration within the ancestral species is significant when compared to lineage-specific rate estimates even after accounting for copy-number polymorphism and homoplasy. We discover striking examples of recurrent and independent gene-containing duplications within the gorilla and chimpanzee that are absent in the human lineage. Our results suggest that the evolutionary properties of copy-number mutation differ significantly from other forms of genetic mutation and, in contrast to the hominid slowdown of single-base-pair mutations, there has been a genomic burst of duplication activity at this period during human evolution.
