新基因的不斷出現(xiàn)是生物進(jìn)化的重要基礎(chǔ),。中國(guó)科學(xué)院昆明動(dòng)物研究所馬普青年科學(xué)家小組在王文研究員的領(lǐng)導(dǎo)下與國(guó)際一些研究小組合作,，已陸續(xù)報(bào)道了包括“sphinx”、“猴王”,、“Hun”,、BSC4等等一系列新近產(chǎn)生的新基因,。這些研究成果表明新基因的起源是一個(gè)重要的生物學(xué)現(xiàn)象。但在全基因組水平,，具體有哪些重要的新基因起源機(jī)制,，它們各自的角色是什么，卻一直不清楚,。
最近,，馬普小組的博士研究生周琦和張國(guó)捷等利用最新發(fā)表的12個(gè)果蠅種的全基因組序列，將新基因起源的研究提升到了闡明全基因組水平模式的高度,。通過大規(guī)模的基因組比較,，鑒定了300多個(gè)果蠅物種特異的年輕基因。對(duì)這些基因起源機(jī)制的分析發(fā)現(xiàn),，基因重復(fù)(gene duplication)是產(chǎn)生新基因最主要的機(jī)制,，80%的新生基因拷貝由串聯(lián)重復(fù)產(chǎn)生，它們之后又可能轉(zhuǎn)化成散在形式的基因重復(fù),。有趣的是,，研究發(fā)現(xiàn)有12%左右的新基因是由非編碼序列“變廢為寶”而來。這一發(fā)現(xiàn)顛覆了該領(lǐng)域長(zhǎng)期存在的“進(jìn)化不可能從頭產(chǎn)生”的觀點(diǎn),，證明從頭起源（de novo origination）是新基因起源不可忽略的重要機(jī)制,。同時(shí)，對(duì)所有新基因及其祖先基因的結(jié)構(gòu)比較發(fā)現(xiàn),，有30%的新基因通過外顯子重排等方式招募祖先基因不具有的序列,，形成了新的嵌合基因(chimeric gene)。這樣的結(jié)構(gòu)為新基因提供了立即獲得新的結(jié)構(gòu)域和功能的機(jī)會(huì),，促使它們可以快速在群體內(nèi)被自然選擇固定,。
上述工作于9月2日被國(guó)際基因組學(xué)知名雜志《基因組研究》（Genome Research）正式發(fā)表。本論文對(duì)理解新遺傳特征的進(jìn)化有重要意義,，引起了國(guó)際同行的廣泛關(guān)注,，Nature Review Genetics特別推薦報(bào)道，發(fā)表于當(dāng)天的英國(guó)The Scientist雜志也采訪了王文研究員,。（生物谷Bioon.com）
生物谷推薦原始出處：
Genome Res. Published online before print July 30, 2008, 10.1101/gr.076588.108
On the origin of new genes in Drosophila
Qi Zhou1,2,4, Guojie Zhang1,2,3,4, Yue Zhang1,4, Shiyu Xu1, Ruoping Zhao1, Zubing Zhan1,2, Xin Li1,2, Yun Ding1,2, Shuang Yang1,3, and Wen Wang1,5
1 CAS-Max Planck Junior Research Group, State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China; 2 Graduate School of Chinese Academy Sciences, Beijing 100086, China; 3 Beijing Genomics Institute-Shenzhen, Shenzhen 518083, China
Several mechanisms have been proposed to account for the origination of new genes. Despite extensive case studies, the general principles governing this fundamental process are still unclear at the whole-genome level. Here, we unveil genome-wide patterns for the mutational mechanisms leading to new genes and their subsequent lineage-specific evolution at different time nodes in the Drosophila melanogaster species subgroup. We find that (1) tandem gene duplication has generated 80% of the nascent duplicates that are limited to single species (D. melanogaster or Drosophila yakuba); (2) the most abundant new genes shared by multiple species (44.1%) are dispersed duplicates, and are more likely to be retained and be functional; (3) de novo gene origination from noncoding sequences plays an unexpectedly important role during the origin of new genes, and is responsible for 11.9% of the new genes; (4) retroposition is also an important mechanism, and had generated 10% of the new genes; (5) 30% of the new genes in the D. melanogaster species complex recruited various genomic sequences and formed chimeric gene structures, suggesting structure innovation as an important way to help fixation of new genes; and (6) the rate of the origin of new functional genes is estimated to be five to 11 genes per million years in the D. melanogaster subgroup. Finally, we survey gene frequencies among 19 globally derived strains for D. melanogaster-specific new genes and reveal that 44.4% of them show copy number polymorphisms within a population. In conclusion, we provide a panoramic picture for the origin of new genes in Drosophila species.
