Uptake of arsenic-betaines by the mussel Mytilus edulis

Mussels (Mytilus edulis) were exposed to trimethyl(carboxymethyl)arsonium bromide (arsenobetaine, C-1 betaine), trimethyl(2- carboxyethyl)arsonium bromide (C-2 betaine), or trimethyl(3-carboxypropyl)arsonium bromide (C-3 betaine). Arsenic was accumulated by the mussels in all cases but the efficiency of uptake decreased with the number of methylene units in the carboxyalkyl group. Arsenobetaine (C-1 betaine) was the most readily accumulated, followed by the C-2 betaine (70% as efficient as arsenobetaine) and the C-3 betaine ( similar to 7%). Chromatographic analysis (HPLC-ICPMS) of extracts of the mussels demonstrated that the arsenic compounds were accumulated uncahanged. A 46-day depuration period which followed exposure did not significantly reduce the arsenic concentration in any of the three groups. Comparison with previous data on accumulation of arsenic compounds by M. edulis indicates that uptake may be influenced by the presence of a quaternary arsonium group and the zwitterionic nature of the arsenic-betaines. (C) 1999 Elsevier Science Inc. All rights reserved.