Mansi Srivastava1, Emina Begovic1,2, Jarrod Chapman2, Nicholas H. Putnam2,9, Uffe Hellsten2, Takeshi Kawashima1,3, Alan Kuo2, Therese Mitros1, Asaf Salamov2, Meredith L. Carpenter1, Ana Y. Signorovitch4,5, Maria A. Moreno4, Kai Kamm7, Jane Grimwood8, Jeremy Schmutz8, Harris Shapiro2, Igor V. Grigoriev2, Leo W. Buss5,6, Bernd Schierwater4,7, Stephen L. Dellaporta4 & Daniel S. Rokhsar1,2

The Trichoplax genome and the nature of placozoans

Nature 454, 955-960 (21 August 2008)
doi:10.1038/nature07191

1.  Center for Integrative Genomics and Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
2.  Department of Energy Joint Genome Institute, Walnut Creek, California 94598, USA
3.  Okinawa Institute of Science and Technology, Uruma, Okinawa 904-2234, Japan
4.  Department of Molecular, Cellular, and Developmental Biology,
5.  Department of Ecology and Evolutionary Biology, and,
6.  Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA
7.  Division of Ecology and Evolution, Institut für Tierökologie und Zellbiologie, Stiftung Tieraerztliche Hochschule Hannover, Bünteweg 17d, D-30559 Hannover, Germany
8.  Stanford Human Genome Center, Stanford University, Stanford, California 94304, USA
9.  Present address: Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas 77005, USA.

Correspondence to: Mansi Srivastava1Daniel S. Rokhsar1,2 Correspondence and requests for materials should be addressed to M.S. (Email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it ) or D.S.R. (Email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it ).

Abstract
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.

 http://www.nature.com/nature/journal/v454/n7207/abs/nature07191.html 

PDF download