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On the evolution of the animal phototransduction cascades.

机译：关于动物光导级联的进化。

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摘要

Animal phototransduction cascades are mediated by the sensory receptor protein opsin. Using a comparative phylogenomics approach, we investigate a global phylogeny for opsin by including sequence data from the genomes of early branching animal lineages. We find that opsin proteins originated prior to the last common ancestor of cnidarians and bilaterians, but were not present in earlier branching animal lineages. Our phylogeny also provides an scaffold for investigations into the molecular basis for phototransduction diversification. Using various statistical measures, we provide compelling evidence that changes in two amino acid residues in particular have underlined the diversification of the various classes of opsin, a finding supported by previous biochemical studies. We further explore the macroevolutionary dynamics of gene duplication and functional co-option that have each flavored the evolutionary history of animal phototransduction.;In order to polarize the wealth of existing data on the composition of bilaterian phototransduction cascades we require an understanding of the ancestral state of this pathway. Focusing on specific ion channel components of this cascade, our studies of gene expression and photobehavior in the cnidarian Hydra magnipapillata provide strong evidence that cnidarian phototransduction relies on Cyclic Nucleotide-Gated ion channels. This finding renders cnidarian phototransduction as similar to the ciliary pathway used by vertebrates and other taxa for vision, in contrast to the rhabdomeric pathway common to insects and other invertebrates. We use these data to investigate ancestral composition of the animal phototransduction. Our results force recognition that the ciliary pathway represents the ancestral state of animal phototransduction, whereas the rhabdomeric pathway is a derived condition.;Our studies have rested heavily on genomic data from the cnidarians H. magnipapillata and Nematostella vectensis. Both of these animals lack eyes but display a rich set of photosensitive phenotypes. In what capacity do these animals integrate photosensitivity into their behavior? We show that opsin and other phototransduction components are expressed in the cnidarian-specific stinging cells known as nematocytes. We further show that light intensity acts to attenuate nematocyte discharge. This finding adds a new dimension to our understanding of basic nematocyte biology and offers a novel context for exploring nematocyte function.
机译：动物光转导级联反应由感觉受体蛋白视蛋白介导。使用比较性系统发育组学方法，我们通过包括来自早期分支动物谱系基因组的序列数据来研究视蛋白的整体系统发育。我们发现视蛋白蛋白起源于cnidarians和bilaterians的最后共同祖先，但在较早的分支动物谱系中不存在。我们的系统发育还为研究光转导多样化的分子基础提供了一个支架。使用各种统计方法，我们提供了令人信服的证据，特别是两个氨基酸残基的变化突出了各种视蛋白的多样性，这一发现得到了先前生化研究的支持。我们进一步探讨了基因复制和功能联用的宏观进化动力学，这些动力学都增添了动物光转导的进化历史。这个途径。着眼于该级联反应的特定离子通道成分，我们对大蓟刺胞中的基因表达和光行为的研究提供了有力的证据，表明刺胞的光转导依赖于环核苷酸门控的离子通道。与昆虫和其他无脊椎动物常见的横纹体途径相反，这一发现使得刺胞的光转导类似于脊椎动物和其他类群用于视觉的睫状途径。我们使用这些数据来调查动物光转导的祖先组成。我们的结果迫使人们认识到，睫状纤毛途径代表了动物光转导的祖先状态，而横纹体途径则是一种衍生条件。这两只动物都没有眼睛，但表现出丰富的光敏表型。这些动物以何种身份将光敏性纳入其行为？我们显示视蛋白和其他光转导成分在称为神经细胞的刺胞特异性刺细胞中表达。我们进一步表明，光强度起到减弱神经细胞放电的作用。这一发现为我们对基本的神经细胞生物学提供了新的视角，并为探索神经细胞功能提供了新的背景。

著录项

  • 作者

    Plachetzki, David C.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Biology Neuroscience.;Biology Zoology.;Biology Bioinformatics.;Biology Evolution and Development.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 147 p.
  • 总页数 147
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:19

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