Evolutionary history of teleost intron-containing and intron-less rhodopsin genes
Evolutionary history of teleost intron-containing and intron-less rhodopsin genes
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DOI：
10.1038/s41598-019-47028-4
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发表时间：
2019-07-23
影响因子：
4.6
通讯作者：
Yamashita, Takahiro
中科院分区：
文献类型：
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作者：
Fujiyabu, Chihiro;Sato, Keita;Yamashita, Takahiro
全基因组测序的最新进展表明，动物有各种各样的视蛋白基因来接受光。其中，大多数视蛋白基因的编码区都有内含子。然而，人们很早就知道硬骨视网膜表达无内含子的视紫红质基因，这被认为是由祖先含有内含子的视紫红质基因的逆转录而形成的。此外，硬骨鱼有一个含有内含子的视紫红质基因(外视紫质)，专门用于松果体的光接收。在这项研究中，为了揭示这两个硬骨鱼视紫红质基因的进化起源，我们分析了放线蕨类中非硬骨鱼的视紫红质基因。对Bichir、鲟鱼和GAR视紫红质基因全长序列的系统发育分析表明，视紫红质基因的逆转录复制发生在Bichir谱系的分支之后。此外，对Bichir、鲟鱼和GAR视紫红质的组织分布和分子性质的分析表明，在GAR谱系分支后，松果体中含有内含子的视紫红质丰富而独特地表达，其Meta II中间体寿命短，从而导致松果体光接收的最优化。基于这些结果，我们提出了一个硬骨鱼含有内含子和无内含子的视紫红质基因的逐步进化模型。
Recent progress in whole genome sequencing has revealed that animals have various kinds of opsin genes for photoreception. Among them, most opsin genes have introns in their coding regions. However, it has been known for a long time that teleost retinas express intron-less rhodopsin genes, which are presumed to have been formed by retroduplication from an ancestral intron-containing rhodopsin gene. In addition, teleosts have an intron-containing rhodopsin gene (exo-rhodopsin) exclusively for pineal photoreception. In this study, to unravel the evolutionary origin of the two teleost rhodopsin genes, we analyzed the rhodopsin genes of non-teleost fishes in the Actinopterygii. The phylogenetic analysis of full-length sequences of bichir, sturgeon and gar rhodopsins revealed that retroduplication of the rhodopsin gene occurred after branching of the bichir lineage. In addition, analysis of the tissue distribution and the molecular properties of bichir, sturgeon and gar rhodopsins showed that the abundant and exclusive expression of intron-containing rhodopsin in the pineal gland and the short lifetime of its meta II intermediate, which leads to optimization for pineal photoreception, were achieved after branching of the gar lineage. Based on these results, we propose a stepwise evolutionary model of teleost intron-containing and intron-less rhodopsin genes.