The Trichoplax genome and the nature of placozoans

作者：Mansi Srivastava, Emina Begović, Jarrod Chapman, Nicholas H. Putnam, Uffe Hellsten, Takeshi Kawashima, Alan Kuo, Therese Mitros, Asaf Salamov, Meredith L. Carpenter, Ana Y. Signorovitch, Maria A. Moreno, Kai Kamm, Jane Grimwood, Jeremy Schmutz, Harris Shapiro, Igor V. Grigoriev, Leo W. Buss, Bernd Schierwater, Stephen L. Dellaporta, Daniel S. Rokhsar · 发表于：Nature · 年份：2008 · DOI：10.1038/nature07191 · 被引用次数：919 · 研究领域：Marine Invertebrate Physiology and Ecology、Parasite Biology and Host Interactions、Marine Ecology and Invasive Species

As arguably the simplest free-living animals, placozoans may represent a primitive metazoan form, yet their biology is poorly understood. Here we report the sequencing and analysis of the ∼98 million base pair nuclear genome of the placozoan Trichoplax adhaerens. Whole-genome phylogenetic analysis suggests that placozoans belong to a ‘eumetazoan’ clade that includes cnidarians and bilaterians, with sponges as the earliest diverging animals. The compact genome shows conserved gene content, gene structure and synteny in relation to the human and other complex eumetazoan genomes. Despite the apparent cellular and organismal simplicity of Trichoplax, its genome encodes a rich array of transcription factor and signalling pathway genes that are typically associated with diverse cell types and developmental processes in eumetazoans, motivating further searches for cryptic cellular complexity and/or as yet unobserved life history stages. Often touted as the 'simplest' free-living animal alive, Trichoplax is central to the debate on early animal origins. It is a disk-shaped placozoan (meaning a 'flat animal') about a millimetre across and was first observed growing on the walls of an aquarium. Now the genome of Trichoplax adhaerens has been sequenced and analysed. The organism retains many features of the last common ancestor with cnidarians and bilaterians, calculated to have existed more than 600 million years ago. But Trichoplax also contains genes for developmental patterns and ce...