Chemoreception in Nassarius obsoletus: the role of specific stimulatory proteins.

Proteins in human plasma and oyster fluid induce a strong feeding response in the marine snail Nassarius obsoletus. Purified human serum albumin induces a 50 percent positive response at concentrations of 1 to 2 x 10(-9) molar. Adsorbed fatty acids markedly decrease the effectiveness of albumin. From oyster fluid a major glycoprotein has been isolated which accounts for essentially the entire stimulatory activity of the fluid and is effective at concentrations of approximately 1 to 2 x 10(-10) molar. These findings provide evidence that specific proteins in extremely low concentrations may play a major role in chemoreception in aquatic animals.