MATUS, D.Q.; LEE, P.N.; BROWNE, W.E.; MARTINDALE, M.Q.; University of Hawaii / Kewalo Marine Laboratory; University of Hawaii / Kewalo Marine Laboratory; University of Hawaii / Kewalo Marine Laboratory; University of Hawaii / Kewalo Marine Laboratory: The role of COE genes in the evolution of the metazoan nervous system

We are interested in the evolution of the nervous system in the Metazoa. We have used PCR to isolate metazoan orthologs to the COE family of genes, named for Collier (col), Olfactory-1 (Olf-1), and Early B-Cell Factor (EBF) originally isolated in Drosophila, rat, and mouse, respectively. COE genes, transcription factors possessing both a DNA binding domain as well as a helix-loop-helix motif, have been shown to play a diverse role during neuronal development in both invertebrates and vertebrates, including neuronal pathfinding and expression in post-mitotic and chemosensory neurons in both the peripheral and central nervous system. Using in situ hybridization we have characterized the expression of this gene in a variety of marine invertebrates displaying a variety of developmental modes, including spiralian development (e.g., mollusks, nemerteans, and polychaetes), radial cleavage (e.g., echinoderms) and life histories (planktonic larval development versus direct developers). In the cnidarian, starlet sea anemone, Nematostella vectensis, COE is expressed in ectodermally derived cells of the apical tuft of the planula stage. On the basis of seretonin staining, it has been suggested that the apical organ of protostome and deuterostome marine larval forms are homologous, and may be the precursor to the bilaterian brain. Given that many invertebrate protostome and deuterostome larvae possess apical sense organs that are known to have chemosensory roles, the expression of COE genes in these organs would provide a link between the apical tuft of cnidarians and bilaterian apical organs, as well as leading to a better understanding of the basal metaozoan nervous system.