TSIE, M; RAWSON, P; LINDSAY, S; University of Maine, Orono ME; University of Maine, Orono ME; University of Maine, Orono ME: Molecular Cloning of Putative Chemosensory G proteins from a Spionid Polychaete

The spionid polychaete, Dipolydora quadrilobata is a marine worm whose feeding behavior is influenced by binding chemical cues. In most organisms, odorant receptors are typically coupled with G proteins. The binding of a chemical cue to an odorant receptor activates G proteins initiating a signal transduction cascade that results in a behavioral response. We are using a molecular biological approach to identify G proteins, which may be involved with the mechanism controlling feeding responses in D. quadrilobata. Sequences of G proteins that interact with receptors have fairly conserved motifs facilitating degenerate primer approaches for sequence isolation. G proteins consist of three subunits, alpha, beta, and gamma, and exist in many different classes. We designed degenerate primers and have successfully cloned partial sequences of Gβ, Gqα, and Gsα from palps, the primary feeding appendages in D. quadrilobata, which are equipped with putative chemosensory cells. The isolated sequences for each type of subunit are well conserved in comparison to sequences drawn from a broad range of phyla. Additional analyses will investigate variation at sites important for receptor and G protein interaction, and complete sequences will be used to design RNA probes investigating patterns of expression in the palps.