UPTAKE OF ORGANIC MATERIAL BY AQUATIC INVERTEBRATES. III. UPTAKE OF GLYCINE BY BRACKISH-WATER ANNELIDS

Abstract

Accumulation of glycine by Nereis limnicola and N. succinea was observed using C14- labelled glycine. Both worms accumulate glycine at high and intermediate salinities, apparently across the body wall. At approximately the salinity where osmotic regulation and chloride regulation of the coelomic fluid begin, the rate of glycine uptake falls dramatically. Acclimation of the physiological system mediating glycine uptake to a change in salinity extends for more than two weeks in N. limnicola. The rate of uptake in N. succinea exceeds that in N. limnicola by an order of magnitude. This is correlated with the distribution of the latter species, which occurs at lower salinities, and with its greater osmoregulatory ability. These findings, together with the widespread ability of marine invertebrates to remove amino acids from solution and the failure to show such uptake in fresh-water forms, leads to the suggestion that the processes of glycine uptake and osmoregulation are incompatible.