a1 The Laboratory, Marine Biological Association, Citadel Hill, Plymouth
Siboglinum ekmani can accumulate labelled alanine, glycine, phenylalanine, glutamic acid, galactose, glucose, mannose, acetic acid, palmitic acid, lactic acid and glycollic acid from sea water at concentrations between 1 and 100 μM/1. Uptake of fructose and mannitol was not detected. The neutral amino acids were absorbed against a concentration gradient, probably by a carrier-mediated transport mechanism, and similar mechanisms may exist for acidic amino acids and glucose. Most of the compounds entered into the metabolism, but 90% of the glycine accumulated was retained as free amino acid. The presence of glucose appeared to depress uptake of alanine, but uptake of glucose was stimulated by alanine.