Cell
Volume 129, Issue 2, 20 April 2007, Pages 277-288
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Article
Molecular Architecture of Annelid Nerve Cord Supports Common Origin of Nervous System Centralization in Bilateria

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Summary

To elucidate the evolutionary origin of nervous system centralization, we investigated the molecular architecture of the trunk nervous system in the annelid Platynereis dumerilii. Annelids belong to Bilateria, an evolutionary lineage of bilateral animals that also includes vertebrates and insects. Comparing nervous system development in annelids to that of other bilaterians could provide valuable information about the common ancestor of all Bilateria. We find that the Platynereis neuroectoderm is subdivided into longitudinal progenitor domains by partially overlapping expression regions of nk and pax genes. These domains match corresponding domains in the vertebrate neural tube and give rise to conserved neural cell types. As in vertebrates, neural patterning genes are sensitive to Bmp signaling. Our data indicate that this mediolateral architecture was present in the last common bilaterian ancestor and thus support a common origin of nervous system centralization in Bilateria.

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EVO ECOL

Cited by (0)

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.