Ringed seal (Phoca hispida) is a major component and a major source of mercury (Hg) in the Inuit traditional diet. A high correlation between Hg and selenium (Se), as different forms of Hg-Se complex, has been reported in many species of marine mammals. The chemical form of the Hg-Se complex in ringed seals has never be characterised. In this study, Hg and Se concentrations in different seal tissues: liver, kidney, muscle and brain, were measured. The highest Hg and Se concentrations were found in the liver and a strong linear correlation was also observed between Hg and Se concentration in the seal liver. Extensive chromatographic and mass spectrometry techniques have been used to isolate and characterize the Hg and Se ligands in seal liver. Extraction of Hg and Se showed that Hg and Se were bound to ligands within the cell membranes of ringed seal liver. The Hg/Se binding protein has a MW range of about 65 kDa and Hg and Se had a 1:1 molecular ratio. The Hg/Se binding protein may contain 3 major polypeptides with MW of 6510.8, 14305.1 and 14353.1 Da. The toxicology of this Hg/Se binding protein will be studied using an animal feeding experiment.

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