Haug Marion F, Gesemann Matthias, Lazović Viktor, Neuhauss Stephan C F
Institute of Molecular Life Sciences, Neuroscience Center Zurich and Center for Integrative Human Physiology, University of Zurich, Switzerland.
Institute of Molecular Life Sciences, Neuroscience Center Zurich and Center for Integrative Human Physiology, University of Zurich, Switzerland
Genome Biol Evol. 2015 Jan 18;7(2):601-19. doi: 10.1093/gbe/evv010.
Cryptochromes (Crys) are light sensing receptors that are present in all eukaryotes. They mainly absorb light in the UV/blue spectrum. The extant Crys consist of two subfamilies, which are descendants of photolyases but are now involved in the regulation of circadian rhythms. So far, knowledge about the evolution, phylogeny, and expression of cry genes is still scarce. The inclusion of cry sequences from a wide range of bilaterian species allowed us to analyze their phylogeny in detail, identifying six major Cry subgroups. Selective gene inactivations and stabilizations in multiple chordate as well as arthropod lineages suggest several sub- and/or neofunctionalization events. An expression study performed in zebrafish, the model organism harboring the largest amount of crys, showed indeed only partially overlapping expression of paralogous mRNA, supporting gene sub- and/or neofunctionalization. Moreover, the daily cry expression in the adult zebrafish retina indicated varying oscillation patterns in different cell types. Our extensive phylogenetic analysis provides for the first time an overview of cry evolutionary history. Although several, especially parasitic or blind species, have lost all cry genes, crustaceans have retained up to three crys, teleosts possess up to seven, and tetrapods up to four crys. The broad and cyclic expression pattern of all cry transcripts in zebrafish retinal layers implies an involvement in retinal circadian processes and supports the hypothesis of several autonomous circadian clocks present in the vertebrate retina.
隐花色素（Crys）是存在于所有真核生物中的光感应受体。它们主要吸收紫外线/蓝光光谱中的光。现存的隐花色素由两个亚家族组成，它们是光解酶的后代，但现在参与昼夜节律的调节。到目前为止，关于隐花色素基因的进化、系统发育和表达的知识仍然匮乏。纳入来自广泛双侧对称动物物种的隐花色素序列使我们能够详细分析它们的系统发育，确定了六个主要的隐花色素亚组。在多个脊索动物以及节肢动物谱系中的选择性基因失活和稳定化表明了几个亚功能化和/或新功能化事件。在斑马鱼（拥有最多隐花色素的模式生物）中进行的一项表达研究确实表明，同源mRNA的表达只是部分重叠，这支持了基因亚功能化和/或新功能化。此外，成年斑马鱼视网膜中隐花色素的每日表达表明不同细胞类型中存在不同的振荡模式。我们广泛的系统发育分析首次概述了隐花色素的进化历史。尽管有几个物种，特别是寄生或失明物种，已经失去了所有隐花色素基因，但甲壳类动物保留了多达三个隐花色素，硬骨鱼拥有多达七个，四足动物多达四个隐花色素。斑马鱼视网膜层中所有隐花色素转录本广泛且周期性的表达模式意味着其参与视网膜昼夜节律过程，并支持脊椎动物视网膜中存在几个自主昼夜节律时钟的假设。
