美國科學家2月11日在《自然》雜志上發(fā)表論文稱，一次目前所知甚少的大規(guī)模爆發(fā)的基因變異將人從大猩猩中分離出來,，也將非洲黑猩猩、大猩猩和猩猩從猴子中分離,。
華盛頓大學遺傳學家埃文·埃什勒和同事發(fā)現(xiàn),，大約1000萬年前，在大猩猩從其它猩猩和猴子中分離出來之前,，它們的DNA開始出現(xiàn)爆炸性的變化——并非傳統(tǒng)的變異,，而是被稱為復制數(shù)量變異的變化,，這些DNA序列的變化可能有助于解釋什么使人類和其它猿類相區(qū)別。
埃什勒也是霍華德·休斯醫(yī)學會的研究人員,，他的團隊分析了人,、黑猩猩、猩猩以及獼猴的這個DNA,。他們認為,，一些在進化樹上不同距離的物種可以被看作時間機器，以追蹤幾千年來所發(fā)生的變化,。
他們發(fā)現(xiàn),，就整個序列來說，人類和非洲黑猩猩非常接近,，主要的區(qū)別在于復制數(shù)量的變化,，也就是同一個遺傳序列重復的次數(shù)不同，刪除的內(nèi)容不同等,。埃什勒說,，在人類中，這些變異同艾滋病和孤獨癥等疾病相關,，這些變異也構(gòu)成了物種之間的差異的基礎,。
分析表明，在靈長類的分支變成非洲大猩猩和人類的過程中,，這些復制的數(shù)量開始增加,，同時，越來越多傳統(tǒng)的基因變異開始緩慢減少,。他們稱,，尤其是人類和非洲黑猩猩，這些序列的額外復制格外多,。
埃什勒說：“在基因組突然被重新排列和發(fā)生變化的地方,，會產(chǎn)生巨大的變化。這些基因可能對語言或某些認知能力很重要,，但還需要做很多工作,。”（生物谷Bioon.com）
生物谷推薦原始出處：
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.
