SCP-Related Peptides From Bivalve Mollusks: Identification, Tissue Distribution, and Actions.

Area of Science:

• Marine Biology
• Peptide Chemistry
• Invertebrate Physiology

Background:

• The SCPs peptide family is known in gastropods for regulating cardiovascular and feeding systems.
• The presence and function of SCPs in Bivalvia, a distinct mollusk class, remained largely uncharacterized.

Purpose of the Study:

• To investigate the manifestation and function of SCPs in bivalves.
• To identify and characterize SCP-related peptides in commercially important bivalve species.

Main Methods:

• Acetone extracts of bivalves were fractionated using High-Pressure Liquid Chromatography (HPLC).
• Reactive peaks were identified via Radioimmunoassay (RIA), followed by purification, sequencing, and Mass Spectrometry.
• Tissue distribution and pharmacological actions were assessed using RIA and organ bath assays on isolated tissues.

Main Results:

• Three novel SCPs were identified in the clam Mercenaria mercenaria; additional related peptides were found in oysters and cockles.
• Highest SCP concentrations were detected in palps and visceral ganglia, with lower levels in other tissues including the heart.
• Bivalve SCPs demonstrated muscle relaxation in the rectum and intestinal typhlosoles, and slowed heart rhythmicity in some cases.

Conclusions:

• The identified bivalve peptides are confirmed homologs of gastropod SCPs.
• Bivalve SCPs play roles in controlling feeding, digestion, and potentially cardiovascular functions, mirroring their gastropod relatives.