Meeting Abstract

29.1  Wednesday, Jan. 4  Regulation of larval chaetogenesis in the brachiopod Terebratalia tranversa by Notch/Delta signaling PASSAMANECK, Y.J.*; SCHIEMANN, S.; MARTINDALE, M.Q.; HEJNOL, A.; Kewalo Marine Laboratory, Univ. of Hawaii; Sars International Centre for Marine Molecular Biology, Bergen, Norway; Kewalo Marine Laboratory, Univ. of Hawaii; Sars International Centre for Marine Molecular Biology, Bergen, Norway yale@hawaii.edu

Chitinous bristles (termed chaetae or setae) occur in the larvae and adults of both articulate and inarticulate brachiopods, and are likely plesiomorphic for the Brachiopoda as a whole. Ultrastructural studies have evidenced that brachiopod chaetae share significant morphological similarities with the chaetae of annelids, presenting the possibility that the structures in the two taxa may be homologous. To gain insight into the molecular mechanisms underlying chaetogenesis in brachiopods, we have investigated the formation of the larval chaetae in the inarticulate brachiopod Terebratalia transversa. In T. transversa four bundles of chaetae are formed at the margin of the mantle lobe during larval development. By comparative analysis of conserved cell-cell signal pathways, we have determined that the core components of the Notch/Delta signaling pathway are expressed in a pattern consistent with the location of the chaetoblast cells, suggesting a possible role for this pathway in the regulation of chaetogenesis. To test the role of the Notch/Delta signaling, developing larvae were treated with DAPT, a gamma-secretase inhibitor that blocks Notch signal transduction. Larvae exposed to DAPT failed to form chaetae, evidencing a role for Notch/Delta signaling in regulating larval chaetogenesis.