Accumulation and subcellular ditsribution of Cd in the Antarctic bivalve Laternula elliptica

Abstract

Accumulation and subcellular partitioning of Cd in the gills, digestive gland, and kidney of the Antarctic bivalve Laternula ellipitca were determined following a 14-day exposure to 50 µgCd·l-1. Cd concentration in the gills increased rapidly reaching up to 20 times of the control levels after 14 days of exposure. Significant increase of Cd was also observed in the digestive gland and kidney. Both the soluble and insoluble particulate fractions of the tissues were involved in Cd accumulation, however, their relative contributions to Cd sequestration varied with the organ and the total amount of Cd accumulated. In the gills and kidney, insoluble particulate fraction was the major Cd sequestering component and the proportion of Cd associated with this fraction increased with the total Cd concentration. In the digestive gland, Cd was accumulated to the soluble and insoluble fractions in similar proportions. Whether it is proportionately large or small, Cd in the soluble fractions was mainly associated with metallothionein-like Cd-binding protein in all the three organs, although the amount of Cd associated with smaller molecular weight peptides increased with exposure time. Strong immune response to an MT antibody confirmed the presence of MT in all three organs. Increase of the amount of Cd bound to MT-like protein was observed with increasing exposure time.