The Occurrence and Retention of Dimethyl-β-Propiothetin in Some Filter-Feeding Organisms

Abstract

Determinations of dimethyl-β-propiothetin (DMPT) levels are reported for 10 filter-feeding organisms, 1 browsing mollusc, 1 carnivorous mollusc, and 1 crustacean. Mature oysters, scallops, and the pteropod Limacina helicina showed high (ca. 0.1 mg/g) DMPT levels, mussels showed generally lower levels, and quahogs and a tunicate showed negligible amounts of DMPT. The periwinkle accumulated DMPT only when feeding on an alga rich in DMPT. Retention of DMPT over prolonged periods was studied in the oyster and in mussels.Seasonal variations, year-to-year variations, and variations with locations were studied for oysters and to a limited extent for mussels. The findings are discussed in terms of food availability and feeding habits and indicate that together with tocopherol it may be possible to correlate DMPT levels with the availability of phytoplankters in the food intake or some species. It is suggested that phagocytes may be responsible for prolonged retention of DMPT in oysters.