Nature2014-06-16 4:58 PM

The ctenophore genome and the evolutionary origins of neural systems栉水母“太平洋侧腕水母”的基因组草图

论文摘要 

栉水母是谜一样的动物,它们将两个截然不同的神经网与一个类似基础大脑的中心结合在一起,并具有适合其捕食性生活方式的、由中胚叶形成的肌肉。Leonid Moroz等人发表了栉水母“太平洋侧腕水母”(Pleurobrachia bachei)的基因组草图以及另外其他十种栉水母的转录组。这些基因组的神经、免疫和发育基因含量与其他动物基因组显著不同:没有HOX基因和标准的微RNA机制,免疫基因补充也减少了。 很多双侧神经元特定基因和“经典”神经传输物通道的基因在神经元中不存在或没有表达。作者提出,栉水母的神经系统(还可能包括肌肉分化)是独立于其他动物的方式演化的。

Abstract 

The origins of neural systems remain unresolved. In contrast to other basal metazoans, ctenophores (comb jellies) have both complex nervous and mesoderm-derived muscular systems. These holoplanktonic predators also have sophisticated ciliated locomotion, behaviour and distinct development. Here we present the draft genome of Pleurobrachia bachei, Pacific sea gooseberry, together with ten other ctenophore transcriptomes, and show that they are remarkably distinct from other animal genomes in their content of neurogenic, immune and developmental genes. Our integrative analyses place Ctenophora as the earliest lineage within Metazoa. This hypothesis is supported by comparative analysis of multiple gene families, including the apparent absence of HOX genes, canonical microRNA machinery, and reduced immune complement in ctenophores. Although two distinct nervous systems are well recognized in ctenophores, many bilaterian neuron-specific genes and genes of ‘classical’ neurotransmitter pathways either are absent or, if present, are not expressed in neurons. Our metabolomic and physiological data are consistent with the hypothesis that ctenophore neural systems, and possibly muscle specification, evolved independently from those in other animals.

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