The octopus genome and the evolution of cephalopod neural and morphological novelties.
The octopus genome and the evolution of cephalopod neural and morphological novelties.
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DOI：
10.1038/nature14668
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发表时间：
2015-08-13
期刊：
影响因子：
64.8
通讯作者：
Rokhsar DS
中科院分区：
文献类型：
--
作者：
Albertin CB;Simakov O;Mitros T;Wang ZY;Pungor JR;Edsinger-Gonzales E;Brenner S;Ragsdale CW;Rokhsar DS
Coleoid头足类动物（章鱼，鱿鱼和乌贼）是活跃的，足智多谋的捕食者，具有丰富的行为剧目。它们拥有无脊椎动物中最大的神经系统，并呈现出其他引人注目的形态学创新，包括相机般的眼睛，可伸缩的手臂，高度衍生的早期胚胎发生，以及所有动物中最复杂的适应性着色系统。为了研究头足类动物大脑和身体创新的分子基础，我们对加州两点章鱼Octopus bimaculoides的基因组和多个转录组进行了测序。我们没有发现章鱼谱系中假设的全基因组复制的证据。章鱼的核心发育和神经元基因库与无脊椎动物双侧性动物的基因库大致相似，除了以前被认为在脊椎动物中唯一扩大的两个基因家族的大规模扩张：原钙粘蛋白，调节神经元发育，和锌指转录因子的C2H2超家族。如前所述，广泛的mRNA编辑在参与神经兴奋性的基因中以及在参与广泛的其他细胞功能的基因中产生转录物和蛋白质多样性。我们鉴定了数百个头足类特有的基因，其中许多在皮肤、吸盘和神经系统等特殊结构中表现出较高的表达水平。最后，我们发现了大规模基因组重排与转座因子扩增密切相关的证据。我们的分析表明，少数基因家族的大量扩张，沿着基因组连锁和重复内容的广泛重塑，在头足类动物形态创新的进化中发挥了关键作用，包括它们庞大而复杂的神经系统。
Coleoid cephalopods (octopus, squid, and cuttlefish) are active, resourceful predators with a rich behavioral repertoire. They have the largest nervous systems among the invertebrates and present other striking morphological innovations including camera-like eyes, prehensile arms, a highly derived early embryogenesis, and the most sophisticated adaptive coloration system among all animals. To investigate the molecular bases of cephalopod brain and body innovations we sequenced the genome and multiple transcriptomes of the California two-spot octopus, Octopus bimaculoides. We found no evidence for hypothesized whole genome duplications in the octopus lineage. The core developmental and neuronal gene repertoire of the octopus is broadly similar to that found across invertebrate bilaterians, except for massive expansions in two gene families formerly thought to be uniquely enlarged in vertebrates: the protocadherins, which regulate neuronal development, and the C2H2 superfamily of zinc finger transcription factors. Extensive mRNA editing generates transcript and protein diversity in genes involved in neural excitability, as previously described, as well as in genes participating in a broad range of other cellular functions. We identified hundreds of cephalopod-specific genes, many of which showed elevated expression levels in such specialized structures as the skin, the suckers, and the nervous system. Finally, we found evidence for large-scale genomic rearrangements that are closely associated with transposable element expansions. Our analysis suggests that substantial expansion of a handful of gene families, along with extensive remodeling of genome linkage and repetitive content, played a critical role in the evolution of cephalopod morphological innovations, including their large and complex nervous systems.