Initial characterization of receptors for molecules that induce the settlement and metamorphosis of Haliotis rufescens larvae

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6700840

Trapido-Rosenthal, H G

Larvae of the marine gastropod mollusc Haliotis refescens are induced to undergo metamorphosis by ..gamma..-aminobutyric acid (GABA) and stereochemically related compounds. The most potent of these inducers is (-)-..beta..-(parachlorophenyl)-GABA (baclofen). The inductive response exhibits positive cooperatively, and is subject to both facilitation (up-regulation) and habituation (down-regulation). Facilitation is brought about by diamino acids such as L-diaminopropionic acid (L-DAPA), and is characterized by decreased Hill coefficients (n/sub H/) and concentration requirements (EC/sub 50/) for inducers. Facilitation does not require the simultaneous presence of facilitating and inducing compounds, and the facilitated state is persistent. Larvae are capable of being up-regulated 2 days before they are capable of undergoing settlement and metamorphosis. Habituation can be brought about by exposure of pre-competent larvae to GABA 4 days prior to the attainment of competence; it is then slowly reversible. Larvae specifically bind tritiated (-)-baclofen in a manner that is saturable with both increasing time of exposure of larvae to, and with increasing concentration of, this compound. Specific binding can be competed for by unlabeled GABA-mimetic inducing molecules; the order of effectiveness of these molecules as competitors for specific binding correlates well with their effectiveness as inducers of metamorphosis. Facilitation of larvae by exposure to diamino acids does not alter their specific binding of tritiated (-)-baclofen. It is concluded from these findings that Haliotis larvae possess receptors for GABA-mimetic compounds.

• Research Organization: California Univ., Santa Barbara (USA)
• OSTI ID: 6700840
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
AMINOBUTYRIC ACID
ANIMALS
AQUATIC ORGANISMS
AUTONOMIC NERVOUS SYSTEM AGENTS
CARBOXYLIC ACIDS
CHEMICAL ACTIVATION
DRUGS
INVERTEBRATES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LARVAE
MEMBRANE PROTEINS
METAMORPHOSIS
MOLLUSCS
NEUROREGULATORS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
RADIORECEPTOR ASSAY
RECEPTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS