Abstract
Each selenium distribution in the midgut gland, as one of the inedible tissues and whole muscle of the several species of bivalves and snails, was investigated in order to clarify the possibility of the available utilization of selenium from the inedible tissues of shellfish, in relation with mercury distribution involved in those tissues. Both levels in the midgut gland in all subjected shellfish was significantly high as that involving the whole muscle and low oxidation states of selenium species existed dominantly in both tissues. On the other hand, the Se/Hg (the molar ratio of selenium to mercury) in the midgut gland of those shellfish as an indicator of the safety of marine products was about the same or higher compared with that involving whole muscle, suggesting that the midgut gland is usually inedible but a significantly safe tissue. However, because the heavy metals such as mercury will tend to accumulate higher in the midgut gland compared with the whole muscle, as a result, the decrease of the molar fraction of bioavailable species of Se(VI) was observed in the midgut gland. These findings suggested that the available utilization of selenium will not be expected from the midgut gland of shellfish, as was not the case of several species of fish previously reported.
