MATUS, DQ*; PANG, K; THOMSEN, GH; MARTINDALE, MQ; University of Hawaii, Kewalo Marine Laboratory; University of Hawaii, Kewalo Marine Laboratory; Stony Brook University, Dept. of Biochemistry and Cell Biology; University of Hawaii, Kewalo Marine Laboratory: Signaling pathway complexity in the development of an anthozoan cnidarian

Cnidarians (corals, sea anemones, and jelly fish) occupy an important phylogenetic position within the Metazoa, as a potential sister group to the Bilateria. As a group, texbooks have long characterized cnidarians as diploblastic and radially symmetrical around their longitudinal axis (the oral-aboral axis). Nematostella vectensis, the starlet sea anemone, a member of the Anthozoa, is currently being developed as a model cnidarian in which to investigate the origins of the mesodermal germ layer and bilaterality, synapomorphies of the Bilateria. Recent work suggests that N. vectensis possesses the molecular framework of anterior-posterior and dorso-ventral axial patterning, belying the sea anemone�s simple morphological appearance. The N. vectensis genome has recently been sequenced, and has provided a useful tool for isolating and characterizing both the complement and deployment of many bilaterian patterning genes and signal transduction pathway members. We report a surprisingly rich complement of key metazoan signal transduction pathway family members and their antagonists, including hedgehog, TGF-�, Wnt, and FGF families, many of which are absent from the derived ecdysozoan model organisms, Drosophila melanogaster and Caenorhabditis elegans. We also show the deployment of members of these signal transduction pathways via in situ hybridization during embryogenesis in N. vectensis that suggest a startling potential role of many of these pathways in both the origins of an endomesodermal germ layer and bilateral symmetry.