Laboratory investigations into the absorption of dissolved free amino acids by the gill of the mussel Mytilus edulis L.

Abstract

Experiments were undertaken to investigate the uptake of dissolved free amino acids by the isolated gill of Mytilus edulis L., from concentrations approximating to those in sea water. Both neutral and basic amino acids were found to be absorbed against a concentration gradient and a proportion of each amino acid was incorporated in the tissue in ethanol-insoluble form. L-alanine was actively absorbed against a gradient by a process following Michaelis-Menten kinetics (Kt O.33mM, Vmax O.38μmoles/g dry wt/min) and was susceptible to metabolic inhibition. 14C D-alanine was absorbed against a concentration gradient and the label incorporated in the tissue in ethanol-insoluble form. The fate of the absorbed amino acids is considered in relation to efflux from and metabolism in the mussel. The significance of amino acid uptake is discussed with reference to their availability in the environment and their contribution to the nutrition of bivalves.