Molecular Mechanisms of Chemosensory Receptors, Signal Transducers, and the Activation of Gene Expression Controlling Establishment of a Marine Symbiosis
Final technical rept. 1 Aug 87-31 Oct 90,
CALIFORNIA UNIV SANTA BARBARA MARINE SCIENCE INST
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OBIECTIVE To characterize the molecular mechanisms by which marine invertebrate larval chemosensory receptors and their associated signal transducers regulate surface attachment and metamorphosis of the larvae in response to chemical signals from the environment and To characterize the molecular mechanisms regulating the activation of specific gene expression in the developmentally arrested marine invertebrate larva, in response to chemical inducers of metamorphosis. We have found that metamorphosis in larvae of the marine mollusc, Haliotis rufescens red abalone, is controlled by exogenous chemical signals recognized and transduced by two convergent chemosensory pathways a morphogenetic pathway activated by a GABA mimetic peptide morphogen encountered by the larvae on surfaces of recruiting host algae, and a regulatory pathway stimulated by lysine in seawater. The system displays both habituation, acting at the level of the morphogenetic pathway receptors and facilitation, mediated by the regulatory pathway. Output and sensitivity of the morphogenetic pathway are amplified as much as 100-fold by stimulation of the regulatory pathway.