Tissue-specific distribution and activity of glutathione S-transferases as biomarkers in bivalve shellfishes

In order to find the relationship between tissue-specific expressions of glutathione S-transferases (GSTs) and their function in preventing effects of environmental toxicants, GSTs were primarily purified by GST-Sepharose 4B affinity chromatography from liver intestine, gill, mantle, and adductor muscle of Asaphis dichotoma, Amusium pleuronectes pleuronectes, and Atactodea striata. Determination of GSTs was also made in samples taken from the tissue muscle enshielding of A. dichotoma and A. striata. Dodecyl sulfate sodium salt polyacrylamide gel electrophoresis (SDS-PAGE) showed that each tissue has its own unique patterns of GSTs. Studies on tissue-specific activity toward 1-chloro-2,4-dinitrobenzene (CDNB), 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-CI), 4-nitrophthalic acid (4-NPA), and ethacrynic acid (ECA) indicated that GSTs from liver intestine exhibited the highest CDNB conjugation activity among all individual tissues from any of the three species sampled. Furthermore, liver intestine and its connected tissue (muscle enshielding) in these shellfishes accounted for more than 50% of the total detoxification toward the xenobiotic electrophile CDNB.