The olfactory receptor gene repertoire in primates and mouse: Evidence for reduction of the functional fraction in primates
The olfactory receptor gene repertoire in primates and mouse: Evidence for reduction of the functional fraction in primates
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DOI：
10.1073/pnas.040580197
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发表时间：
2000-03-14
影响因子：
11.1
通讯作者：
Giorgi, D
中科院分区：
文献类型：
--
作者：
Rouquier, S;Blancher, A;Giorgi, D
嗅觉受体（ORs）位于鼻上皮嗅觉感觉神经元的细胞膜上，通过结合特异性气味配体来负责气味检测。灵长类动物被认为相对于其他哺乳动物如狗或啮齿动物具有降低的嗅觉（microsmatic）。我们之前已经证明，超过70%的人类OR基因已经成为无功能的假基因，这使我们假设嗅觉的降低可能与功能基因的丧失有关。为了扩展这些结果，我们对10种灵长类动物的OR基因库进行了采样，从原猴猴到人类，还有小鼠。分析了约221个先前未鉴定的灵长类动物序列和33个小鼠序列。这些序列编码分布在7个家族和56个亚家族中的OR。分析表明，在类人猿中假基因的比例很高（平均约50%），相比之下，在旧大陆猴中只有约27%的OR基因是假基因，而新大陆猴几乎没有假基因。原猴分支似乎与其他灵长类动物进化不同，具有约37%的假基因含量。在小鼠中未发现假基因。除了新世界的猴子，我们证明，灵长类动物有一个高比例的OR假基因相比，小鼠。我们假设，在宽松的选择性约束下，灵长类动物将逐步积累的假基因的最高水平在类人猿，假基因的比例在OR基因库可以平行的嗅觉感觉功能的进化。
Olfactory receptors (ORs) located in the cell membrane of olfactory sensory neurons of the nasal epithelium are responsible for odor detection by binding specific odorant ligands. Primates are thought to have a reduced sense of smell (microsmatic) with respect to other mammals such as dogs or rodents. We have previously demonstrated that over 70% of the human OR genes have become nonfunctional pseudogenes, leading us to hypothesize that the reduced sense of smell could correlate with the loss of functional genes. To extend these results, we sampled the OR gene repertoire of 10 primate species, from prosimian lemur to human, in addition to mouse. About 221 previously unidentified primate sequences and 33 mouse sequences were analyzed. These sequences encode ORs distributed in seven families and 56 subfamilies. Analysis showed a high fraction (approximate to 50% on average) of pseudogenes in hominoids, In contrast, only approximate to 27% of OR genes are pseudogenes in Old World monkeys, and New World monkeys are almost free of pseudogenes, The prosimian branch seems to have evolved differently from the other primates and has approximate to 37% pseudogene content. No pseudogenes were found in mouse. With the exception of New World monkeys, we demonstrate that primates have a high fraction of OR pseudogenes compared with mouse. We hypothesize that under relaxed selective constraints, primates would have progressively accumulated pseudogenes with the highest level seen in hominoids, The fraction of pseudogenes in the OR gene repertoire could parallel the evolution of the olfactory sensory function.