MOLECULAR-CHANGES INDUCED BY METAMORPHOSIS IN LARVAE OF THE PROSOBRANCH CONCHOLEPAS-CONCHOLEPAS BRUGUIERE (MOLLUSCA, GASTROPODA, MURICIDAE)

Metamorphosis may be the most critical point in the life history of ma rine molluscs. Excess potassium was used to trigger the metamorphic pr ocess in competent larvae of the prosobranch Concholepas concholepas B ruguiere. The specific, irreversible stimulation of complex morphogene tic events by this exogenous factor was used to study some molecular c hanges that occur during metamorphosis. Results show that metamorphosi s entails several molecular changes, including: (1) a modification in the pattern of protein synthesis measured by incorporation of [S-35]me thionine to newly synthetized polypeptides, (2) an increase of [S-35]m ethionine incorporation in heparin-binding proteins or the induction o f heparin-binding proteins (i.e. growth factors?), (3) a decrease (20 times) in the larval levels of the second messenger cyclic AMP, and (4 ) the appearance of a new form of the neurotransmitter-related enzyme, acetylcholinesterase (AChE). To our knowledge this is the first attem pt to characterize some of the molecular changes that take place durin g molluscan metamorphosis.