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The ctenophore genome and the evolutionary origins of neural systems

2014; Nature Portfolio; Volume: 510; Issue: 7503 Linguagem: Inglês

10.1038/nature13400

1476-4687

Leonid L. Moroz, Kevin M. Kocot, Mathew R. Citarella, Dosung Sohn, Tigran P. Norekian, Inna Povolotskaya, Anastasia P. Grigorenko, Christopher A. Dailey, Eugène Berezikov, Katherine M. Buckley, Andrey Ptitsyn, Denis A. Reshetov, Krishanu Mukherjee, Tatiana P. Moroz, Yelena Bobkova, Fahong Yu, Vladimir V. Kapitonov, Jerzy Jurka, Yuri V. Bobkov, Joshua J. Swore, David O. Girardo, Alexander Fodor, Fedor Gusev, Rachel Sanford, Rebecca Bruders, Ellen L. W. Kittler, Claudia E. Mills, Jonathan P. Rast, Romain Derelle, Victor Solovyev, Fyodor A. Kondrashov, Billie J. Swalla, Jonathan V. Sweedler, Е. И. Рогаев, Kenneth M. Halanych, Andrea B. Kohn,

Plant and Biological Electrophysiology Studies

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. The draft genome of the ctenophore Pleurobrachia bachei (Pacific sea gooseberry) is presented, together with ten other ctenophore transcriptomes — these genomes have a very different neurogenic, immune and developmental gene content when compared with other animal genomes, and it is proposed that ctenophore neural systems, and possibly muscle specification, evolved independently from those in other animals. Ctenophores (comb jellies) are enigmatic animals that combine two distinct nervous systems with an elementary brain-like centre and possess mesoderm-derived muscles appropriate to their predatory lifestyle. Leonid Moroz et al. present the draft genome of the ctenophore Pleurobrachia bachei (Pacific sea gooseberry), together with ten other ctenophore transcriptomes. These genomes have a neurogenic, immune and developmental gene content that differs markedly from other animal genomes: HOX genes and canonical microRNA machinery are absent, and the immune gene complement is reduced. Many bilaterian neuron-specific genes and genes of 'classical' neurotransmitter pathways either are absent or not expressed in neurons. The authors propose that ctenophore neural systems, and possibly muscle specification, evolved independently from those in other animals.