Molecular Architecture of Annelid Nerve Cord Supports Common Origin of Nervous System Centralization in Bilateria Alexandru S. Denes,1,6 Ga´ spa´ rJe´ kely,1,6 Patrick R.H. Steinmetz,1,4 Florian Raible,1 Heidi Snyman,1 Benjamin Prud’homme,2,5 David E.K. Ferrier,3 Guillaume Balavoine,2 and Detlev Arendt1,* 1 Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, 69117, Germany 2 Centre de Ge´ ne´ tique Mole´ culaire, CNRS, Gif-sur-Yvette 91198, France 3 Department of Zoology, University of Oxford, Oxford, OX1 3PS, United Kingdom 4 Present address: Sars Centre, Thormøhlensgt. 55, N-5008 Bergen, Norway. 5 Present address: Institut de Biologie du Developpement de Marseille Luminy, UMR 6216 Case 907, Parc Scientifique de Luminy, 13288 Marseille Cedex 09, France. 6 These authors contributed equally to this work. *Correspondence:
[email protected] DOI 10.1016/j.cell.2007.02.040 SUMMARY comparative molecular analysis of the conserved Bmp (Dpp) dorsoventral patterning cascades revived the idea To elucidate the evolutionary origin of nervous of dorsoventral axis inversion (reviewed in Arendt and Nu¨ - system centralization, we investigated the mo- bler-Jung, 1994; De Robertis and Sasai, 1996), and reini- lecular architecture of the trunk nervous system tiated a discussion on the possible homology of the ventral in the annelid Platynereis dumerilii. Annelids be- invertebrate and dorsal vertebrate CNS. This was fuelled long to Bilateria, an evolutionary lineage of bi- by molecular data revealing a similar mediolateral se- lateral animals that also includes vertebrates quence of nk2.2+, gsx+, and msx+ neurogenic domains in the insect and vertebrate neuroectoderm (Arendt and and insects.