Genome Technology Branch, Division of Intramural Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Science. 2013 Dec 13;342(6164):1242592. doi: 10.1126/science.1242592.
An understanding of ctenophore biology is critical for reconstructing events that occurred early in animal evolution. Toward this goal, we have sequenced, assembled, and annotated the genome of the ctenophore Mnemiopsis leidyi. Our phylogenomic analyses of both amino acid positions and gene content suggest that ctenophores rather than sponges are the sister lineage to all other animals. Mnemiopsis lacks many of the genes found in bilaterian mesodermal cell types, suggesting that these cell types evolved independently. The set of neural genes in Mnemiopsis is similar to that of sponges, indicating that sponges may have lost a nervous system. These results present a newly supported view of early animal evolution that accounts for major losses and/or gains of sophisticated cell types, including nerve and muscle cells.
对水螅水母生物学的了解对于重建动物进化早期发生的事件至关重要。为此，我们对水螅水母栉水母属 Mnemiopsis leidyi 的基因组进行了测序、组装和注释。我们对氨基酸位置和基因含量的系统基因组学分析表明，栉水母而非海绵动物是所有其他动物的姐妹谱系。Mnemiopsis 缺乏许多在两侧对称动物中发现的中胚层细胞类型的基因，这表明这些细胞类型是独立进化的。Mnemiopsis 的神经基因集与海绵动物的相似，这表明海绵动物可能失去了神经系统。这些结果提出了一种新的早期动物进化观点，该观点解释了包括神经和肌肉细胞在内的复杂细胞类型的重大损失和/或获得。
