Evolution of the Genetic Machinery of the Visual Cycle: A Novelty of the Vertebrate Eye?
Evolution of the Genetic Machinery of the Visual Cycle: A Novelty of the Vertebrate Eye?
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DOI：
10.1093/molbev/msr313
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发表时间：
2012-05-01
影响因子：
10.7
通讯作者：
Albalat, Ricard
中科院分区：
文献类型：
--
作者：
Albalat, Ricard
在无脊椎动物中发现的睫状光感受器细胞和纤毛(C)-视蛋白证实，在脊椎动物进化之前，表征脊椎动物光感受器系统的三种元素中至少有两种已经存在。然而，第三种元素的来源仍然不确定，这是一系列被称为“类维A酸循环”的生化反应。为了了解视黄醇周期的进化，我在无脊椎动物基因组中搜索了该周期的遗传机制，特别是头索文昌鱼。文昌鱼与脊椎动物关系密切，具有相当典型的基因组，并具有睫状光感受器细胞和c-opsins。与脊椎动物机械相关的文昌鱼序列的系统发育和结构分析并不支持文昌鱼蛋白在生色团再生中的作用，但表明文昌鱼类周期的遗传机制是由于祖先的非视觉基因的重复而产生的。这些结果支持这样的假设，即视黄醇循环机械是原始脊椎动物眼睛的功能创新。
The discovery in invertebrates of ciliary photoreceptor cells and ciliary (c)-opsins established that at least two of the three elements that characterize the vertebrate photoreceptor system were already present before vertebrate evolution. However, the origin of the third element, a series of biochemical reactions known as the "retinoid cycle," remained uncertain. To understand the evolution of the retinoid cycle, I have searched for the genetic machinery of the cycle in invertebrate genomes, with special emphasis on the cephalochordate amphioxus. Amphioxus is closely related to vertebrates, has a fairly prototypical genome, and possesses ciliary photoreceptor cells and c-opsins. Phylogenetic and structural analyses of the amphioxus sequences related with the vertebrate machinery do not support a function of amphioxus proteins in chromophore regeneration but suggest that the genetic machinery of the retinoid cycle arose in vertebrates due to duplications of ancestral nonvisual genes. These results favor the hypothesis that the retinoid cycle machinery was a functional innovation of the primitive vertebrate eye.