Meeting Abstract

P2.45  Monday, Jan. 5  The receptor and signal-transduction pathway that mediate planular settlement of the coral Pocillopora damicornis TRAN, Cawa*; HADFIELD, Michael G.; University of Hawaii at Manoa; University of Hawaii at Manoa cawa@hawaii.edu

Larvae of the scleractinian coral Pocillopora damicornis are induced to settle and metamorphose by the presence of marine bacterial biofilms. The swimming planula requires this natural cue to select a suitable substratum, attach and grow into a benthic polyp. However, not all bacteria are inductive, and the inductive capacity of each strain is highly species-specific. Induction is mediated by a receptor that detects the external cue and triggers a signal-transduction pathway that initiates metamorphosis. The primary goal of this study is to determine what type of receptor and signal-transduction pathway are involved during metamorphosis of P. damicornis, a basal metazoan, to better understand metamorphosis of invertebrate larvae. Evidence from studies on larvae of hydrozoans and another anthozoan suggest that G protein-coupled receptors (GPCRs) and fibroblast growth factors (FGFs), respectively, are good candidates. In addition, other possible receptor types include lectins and ligand-gated ion channels. Preliminary results suggest that a mannose-binding lectin is localized in the apical region of the larvae of P. damicornis. Current experiments include settlement assays in which competent larvae are exposed to neuropharmacological agents that affect a specific type of receptor and/or pathway, in the presence and absence of biofilm. Agents tested here induce, inhibit, or do not affect metamorphosis of these larvae. This study provides insight into the underlying physiological mechanisms that regulate metamorphosis in the larvae of P. damicornis, in comparison to other invertebrate taxa.