Assimilation of polychlorinated biphenyls by a marine mollusc and comparison with a rat

The marine mollusc Aplysia californica was fed seaweed Rhodymenia palmata contaminated with polychlorinated biphenyls (PCBs) at a high (experimental) and low (control) level for a period of 18 days in flow-through systems which limited the animals to dietary uptake. The assimilation of PCBs, determined by subtraction of fecal output from food intake, was greater at the high dosage (94 +/- 29%) than at the low dosage (84 +/- 22%). Assimilation selectivity of the different congeners favored those with lower chlorine content, and discriminated against those chlorinated in the para position on one of the rings. After assimilation, selectivity for incorporation into the hepatopancreas favored those congeners with higher chlorine contents over those with but 1 to 3 chlorines on the molecule. Similarities between incorporation into the liver of rats and into the hepatopancreas of Aplysia were found, suggesting that common mechanisms for bioaccumulation, and by extension, physiological effects, may be present in such diverse species of the animal kingdom.