Evolutionary dynamics of olfactory receptor genes in fishes and tetrapods
Evolutionary dynamics of olfactory receptor genes in fishes and tetrapods
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DOI：
10.1073/pnas.0501922102
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发表时间：
2005-04-26
影响因子：
11.1
通讯作者：
Nei, M
中科院分区：
文献类型：
--
作者：
Niimura, Y;Nei, M
嗅觉是哺乳动物生存的重要生理功能，受嗅觉受体(OR)基因多基因家族控制。鱼类也有这个基因家族，但已知的基因数量比哺乳动物的要少得多。为了了解OR基因的进化动态，我们对斑马鱼、河豚、青蛙、鸡、人和老鼠的基因组序列中鉴定的所有功能基因进行了系统发育分析。结果表明，鱼类和四足动物的最新共同祖先至少有9个祖先OR基因，所有已鉴定的OR基因可分为9个组，每个组起源于一个祖先基因。9个组基因中有8个仍在鱼类中观察到，而在哺乳动物基因组中只有2个组基因，表明鱼类中的OR基因家族比哺乳动物中的OR基因家族更加多样化。然而，在哺乳动物中，有一组基因--伽马基因--得到了极大的扩展，包含了整个基因家族的近90%。有趣的是，在哺乳动物或鸟类中观察到的基因群在鱼类中几乎没有。青蛙的OR基因谱与鱼类的OR基因谱一样多样，但也出现了群体伽马基因的扩增，表明青蛙OR基因家族既具有哺乳动物的特征，也具有鱼类的特征。所有这些观察都可以用生物体从所有脊椎动物的共同祖先时代到现在所经历的环境变化来解释。
Olfaction, which is an important physiological function for the survival of mammals, is controlled by a large multigene family of olfactory receptor (OR) genes. Fishes also have this gene family, but the number of genes is known to be substantially smaller than in mammals. To understand the evolutionary dynamics of OR genes, we conducted a phylogenetic analysis of all functional genes identified from the genome sequences of zebrafish, pufferfish, frogs, chickens, humans, and mice. The results suggested that the most recent common ancestor between fishes and tetrapods had at least nine ancestral OR genes, and all OR genes identified were classified into nine groups, each of which originated from one ancestral gene. Eight of the nine group genes are still observed in current fish species, whereas only two group genes were found from mammalian genomes, showing that the OR gene family in fishes is much more diverse than in mammals. In mammals, however, one group of genes, gamma, expanded enormously, containing approximate to 90% of the entire gene family. Interestingly, the gene groups observed in mammals or birds are nearly absent in fishes. The OR gene repertoire in frogs is as diverse as that in fishes, but the expansion of group gamma genes also occurred, indicating that the frog OR gene family has both mammal- and fish-like characters. All of these observations can be explained by the environmental change that organisms have experienced from the time of the common ancestor of all vertebrates to the present.