Orthologous divergence and paralogous anticonvergence in molecular evolution of triplicated green opsin genes in medaka fish, genus Oryzias
Orthologous divergence and paralogous anticonvergence in molecular evolution of triplicated green opsin genes in medaka fish, genus Oryzias
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青鳉鱼三倍绿色视蛋白基因分子进化中的直系同源分歧和旁系同源反收敛
DOI：
10.1093/gbe/evaa111
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发表时间：
2020
影响因子：
3.3
通讯作者：
S.
中科院分区：
文献类型：
--
作者：
Matsumoto;Y.;Oda;S.;Mitani;H. and Kawamura;S.
绿视蛋白（RH2）基因的基因复制及其光谱分化在硬骨鱼中有很好的记录。然而，它们在系统发育接近但生态多样的物种之间的进化分化或保护模式尚未得到很好的探索。米达卡鱼（米达卡属）广泛分布于亚洲的淡水和咸淡水中，许多种类是实验室饲养的，可用于遗传研究。我们先前发现日本稻属（Oryzias latipes）具有三个RH2视蛋白基因（RH2- a，RH2- b和RH2- c）编码光谱发散的光色素。在这里，我们检查了三个RH2视蛋白基因从六个物种代表三个物种群：猿猴，古猿猴和爪哇猿猴。光色素重构结果表明，不同种类RH2-A的吸收光谱峰（λmax）存在差异（447 ~ 469 nm），而RH2-B和RH2-C的吸收光谱峰（λmax）较为保守（分别为516 ~ 519 nm和486 ~ 493 nm）。对于RH2-A视蛋白，最大的光谱位移是在系统发育分支中检测到的。单个氨基酸替换T94C解释了大部分的光谱位移。对于RH2-B和c视蛋白，我们检测到两个基因之间的基因转换束，使它们均匀化。然而，几个氨基酸的差异仍然存在。我们发现两种视蛋白之间的光谱差异主要归因于122位点的E/Q氨基酸差异和几个单独具有小光谱效应的位点。这些结果描述了在系统发育接近但生态多样化的物种中，以medaka为例的同源和同源绿色视蛋白基因的光谱分化动态。
Gene duplication of green (RH2) opsin genes and their spectral differentiation are well documented in many teleost fish. However, their evolutionary divergence or conservation patterns among phylogenetically close but ecologically diverse species is not well explored. Medaka fish (genusOryzias) are broadly distributed in fresh and brackish waters of Asia, with many species being laboratory-housed and feasible for genetic studies. We previously showed that a Japan strain (HNI) of medaka (Oryzias latipes) possessed three RH2 opsin genes (RH2-A,RH2-B, andRH2-C) encoding spectrally divergent photopigments. Here, we examined the three RH2 opsin genes from sixOryziasspecies representing three species groups: thelatipes, thecelebensis, and thejavanicus. Photopigment reconstitution revealed that the peak absorption spectra (λmax) of RH2-A were divergent among the species (447–469 nm), whereas those of RH2-B and RH2-C were conservative (516–519 and 486–493 nm, respectively). For the RH2-A opsins, the largest spectral shift was detected in the phylogenetic branch leading to thelatipesgroup. A single amino acid replacement T94C explained most of the spectral shift. For RH2-B and -C opsins, we detected tracts of gene conversion between the two genes homogenizing them. Nevertheless, several amino acid differences were maintained. We showed that the spectral difference between the two opsins was attributed to largely the E/Q amino acid difference at the site 122 and to several sites with individually small spectral effects. These results depict dynamism of spectral divergence of orthologous and paralogous green opsin genes in phylogenetically close but ecologically diverse species exemplified by medaka.