家犬作為人類最親密的朋友，在人類歷史上一直扮演者重要的作用,。更重要的是,，家犬是人類最早馴化的家養(yǎng)動(dòng)物，由于其經(jīng)過(guò)了馴化和品種培育兩個(gè)重要的群體歷史階段,，并且在家養(yǎng)哺乳動(dòng)物中形成了最具多樣性的品種,，因此家犬一直是研究人工選擇和自然選擇的重要模式生物。中國(guó)最為家犬的馴化地,，不僅遺傳多樣性最為豐富,，而且由于其龐大的鄉(xiāng)村狗種群數(shù)量，為研究家犬提供了最為豐富的材料,。在家犬和人類的共同歷史中，嗅覺(jué)發(fā)揮了極其重要的作用,，研究家犬的嗅覺(jué)受體基因很有意義,。
在導(dǎo)師張亞平院士的指導(dǎo)下，中科院昆明動(dòng)物研究所博士生陳睿對(duì)家犬嗅覺(jué)受體基因家族中的分離假基因,，在狼及中國(guó)土狗以及已經(jīng)發(fā)表的品種犬的數(shù)據(jù)進(jìn)行分析,。在各自特有的多態(tài)性位點(diǎn)中，品種犬中存在著很強(qiáng)的負(fù)選擇,，而狼和中國(guó)土狗近乎中性,。但是，通過(guò)對(duì)非同義位點(diǎn)的進(jìn)一步的細(xì)分,，研究發(fā)現(xiàn)狼中的嗅覺(jué)受體基因在積累著無(wú)害突變,，去除有害突變,，而嗅覺(jué)受體在中國(guó)土狗中近乎中性。隨后,，研究人員通過(guò)對(duì)多態(tài)性位點(diǎn)在七次跨膜結(jié)構(gòu)上分布的分析,，進(jìn)一步驗(yàn)證了這個(gè)結(jié)論，并且對(duì)各個(gè)群體特有多態(tài)性及共有多態(tài)性的分析,，發(fā)現(xiàn)選擇作用在祖先群體及狼的嗅覺(jué)受體基因中精細(xì)微妙,，而其在品種犬中就未有這種效果。
研究結(jié)果不僅顯示了在家犬兩次重要?dú)v史階段后,，家犬的嗅覺(jué)受體基因所受的選擇作用發(fā)生了兩次深刻的變化,，而且展示了自然選擇和人工選擇的不同，為以后的品種培育及改良提供了借鑒,。
該工作近期在Molecular Biology and Evolution雜志在線發(fā)表,。（生物谷Bioon.com）
doi:10.1093/molbev/mss153
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PMID:
Differences in selection drive olfactory receptor genes in different directions in dogs and wolf
Rui Chen1,2, David M Irwin1,3 and Ya-Ping Zhang1,4
The olfactory receptor (OR) gene family is the largest gene family found in mammalian genomes. The OR gene family is known to evolve through a birth-and-death process. Here we characterized the sequences of 16 segregating OR pseudogenes in samples of the wolf and the Chinese village dog (CVD), and compared them with the sequences from dogs of different breeds. Our results show that the segregating OR pseudogenes in breed dogs are under strong purifying selection, while evolving neutrally in the CVD, and show a more complicated pattern in the wolf. In the wolf we found a trend to remove deleterious polymorphisms and accumulate non-deleterious polymorphisms. Based on the protein structure of the ORs, we found that the distribution of different types of polymorphisms (synonymous, nonsynonymous, tolerated and untolerated) varied greatly between the wolf and the breed dogs. In summary, our results suggest that different forms of selection have acted on the segregating OR pseudogenes in the CVD since domestication, breed dogs after breed formation, and in the ancestral wolf population, that has driven the evolution of these genes in different directions.
