A study of molecular evolutionary and population genetics of olfactory receptor genes family : Cloning of putative olfactory receptor genesin Medaka, Oryzias latipes.

为了阐明嗅觉的遗传基础、维持遗传多样性的机制以及脊椎动物嗅觉受体基因家族的起源，本研究以果蝇和青鳉鱼（Oryzias latipes）的嗅觉受体基因为研究对象，利用一组简并寡核苷酸引物，从青鳉基因组DNA中成功克隆了4个嗅觉受体基因，分别命名为mfOR 1、mfOR 2、mfOR 3和mfOR 4。所有推导的氨基酸序列均含有7个疏水结构域和几个嗅觉受体常见的序列基序。这四种青鳉受体彼此之间具有19-91%的序列相似性。在氨基酸水平上，有4个受体基因与鲶鱼和斑马鱼的嗅觉受体序列有很高的同源性。这些结果表明，它们编码的是嗅觉受体基因家族的新成员，连锁分析表明，这四个受体基因可分为两个簇。mfOR 3和mfOR 4连锁在青鳉连锁群XX中，与哺乳动物同线性。此外，NJ方法的系统发育分析表明，青鳉嗅觉受体分支很好地从四足动物。

To elucidate the genetic basis of olfaction, the mechanisms that maintain genetic diversity and the origin of vertebrate olfactory receptor gene family, we have tried to clone the olfactory receptor genes of Drosophila and medaka fish (Oryzias latipes).From medaka genomic DNA,four receptor genes, named mfOR1, mfOR2, mfOR3 and mfOR4, were successfully cloned using a set of degenerate oligonucleotides as PCR primers. All of their deduced amino acid sequences contained seven hydrophobic domains and several sequence motifs commonly seen in the olfactory receptors. The four medaka receptors exhibit from 19-91% sequence similarity to each other. At amino acid level, four receptor genes show high homologies with the olfactory receptor sequences from catfish and zebra fish. These results suggested that they encode novel members of olfactory receptor gene family.Linkage analysis have revealed that the four receptor genes are grouped into two clusters. The cluster of mfOR3 and mfOR4 linked in medaka linkage group XX which showed synteny with the mammals. Furthermore, phylogenetic analysis by NJ method revealed that medaka olfactory receptors branches well from the tetrapod vertebrate.