State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Jiaochang East Road 32, Kunming 650223, China.
J Genet Genomics. 2011 Dec 20;38(12):577-84. doi: 10.1016/j.jgg.2011.10.004. Epub 2011 Dec 3.
The evolution of the central nervous system (CNS) is one of the most striking changes during the transition from invertebrates to vertebrates. As a major source of genetic novelties, gene duplication might play an important role in the functional innovation of vertebrate CNS. In this study, we focused on a group of CNS-biased genes that duplicated during early vertebrate evolution. We investigated the tempo-spatial expression patterns of 33 duplicate gene families and their orthologs during the embryonic development of the vertebrate Xenopus laevis and the cephalochordate Brachiostoma belcheri. Almost all the identified duplicate genes are differentially expressed in the CNS in Xenopus embryos, and more than 50% and 30% duplicate genes are expressed in the telencephalon and mid-hindbrain boundary, respectively, which are mostly considered as two innovations in the vertebrate CNS. Interestingly, more than 50% of the amphioxus orthologs do not show apparent expression in the CNS in amphioxus embryos as detected by in situ hybridization, indicating that some of the vertebrate CNS-biased duplicate genes might arise from non-CNS genes in invertebrates. Our data accentuate the functional contribution of gene duplication in the CNS evolution of vertebrate and uncover an invertebrate non-CNS history for some vertebrate CNS-biased duplicate genes.
中枢神经系统（CNS）的进化是从无脊椎动物到脊椎动物过渡过程中最显著的变化之一。作为遗传新特性的主要来源，基因复制可能在脊椎动物 CNS 的功能创新中发挥重要作用。在这项研究中，我们专注于一组在早期脊椎动物进化过程中复制的偏向 CNS 的基因。我们研究了 33 个复制基因家族及其脊椎动物非洲爪蟾和头索动物文昌鱼胚胎发育过程中的时空表达模式。在非洲爪蟾胚胎中，几乎所有鉴定出的复制基因都在 CNS 中呈现差异表达，超过 50%和 30%的复制基因分别在端脑和中后脑边界表达，这两个区域被认为是脊椎动物 CNS 的两个创新区域。有趣的是，通过原位杂交检测，文昌鱼胚胎中的大部分同源基因在 CNS 中没有明显表达，这表明一些偏向 CNS 的脊椎动物复制基因可能来源于无脊椎动物的非 CNS 基因。我们的数据强调了基因复制在脊椎动物 CNS 进化中的功能贡献，并揭示了一些偏向 CNS 的脊椎动物复制基因在无脊椎动物 CNS 中的历史。
