Ramirez M Desmond, Pairett Autum N, Pankey M Sabrina, Serb Jeanne M, Speiser Daniel I, Swafford Andrew J, Oakley Todd H
Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA.
Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA.
Genome Biol Evol. 2016 Dec 1;8(12):3640-3652. doi: 10.1093/gbe/evw248.
The opsin gene family encodes key proteins animals use to sense light and has expanded dramatically as it originated early in animal evolution. Understanding the origins of opsin diversity can offer clues to how separate lineages of animals have repurposed different opsin paralogs for different light-detecting functions. However, the more we look for opsins outside of eyes and from additional animal phyla, the more opsins we uncover, suggesting we still do not know the true extent of opsin diversity, nor the ancestry of opsin diversity in animals. To estimate the number of opsin paralogs present in both the last common ancestor of the Nephrozoa (bilaterians excluding Xenoacoelomorpha), and the ancestor of Cnidaria + Bilateria, we reconstructed a reconciled opsin phylogeny using sequences from 14 animal phyla, especially the traditionally poorly-sampled echinoderms and molluscs. Our analysis strongly supports a repertoire of at least nine opsin paralogs in the bilaterian ancestor and at least four opsin paralogs in the last common ancestor of Cnidaria + Bilateria. Thus, the kernels of extant opsin diversity arose much earlier in animal history than previously known. Further, opsins likely duplicated and were lost many times, with different lineages of animals maintaining different repertoires of opsin paralogs. This phylogenetic information can inform hypotheses about the functions of different opsin paralogs and can be used to understand how and when opsins were incorporated into complex traits like eyes and extraocular sensors.
视蛋白基因家族编码动物用于感光的关键蛋白质，并且自其在动物进化早期起源以来已大幅扩展。了解视蛋白多样性的起源可以为动物的不同谱系如何将不同的视蛋白旁系同源物重新用于不同的光检测功能提供线索。然而，我们在眼睛之外以及从更多动物门类中寻找视蛋白的次数越多，发现的视蛋白就越多，这表明我们仍然不知道视蛋白多样性的真正范围，也不知道动物中视蛋白多样性的祖先情况。为了估计肾管动物（不包括异无腔动物的两侧对称动物）的最后共同祖先以及刺胞动物 + 两侧对称动物的祖先中存在的视蛋白旁系同源物的数量，我们使用来自14个动物门类的序列，特别是传统上采样不足的棘皮动物和软体动物，重建了一个协调的视蛋白系统发育树。我们的分析有力地支持了两侧对称动物祖先中至少有九个视蛋白旁系同源物以及刺胞动物 + 两侧对称动物的最后共同祖先中至少有四个视蛋白旁系同源物。因此，现存视蛋白多样性的核心在动物历史中出现的时间比以前所知的要早得多。此外，视蛋白可能多次重复和丢失，不同的动物谱系保留了不同的视蛋白旁系同源物库。这种系统发育信息可以为关于不同视蛋白旁系同源物功能的假设提供依据，并可用于了解视蛋白如何以及何时被纳入眼睛和眼外传感器等复杂特征中。
