Tissue specific responses of oysters, Crassostrea virginica, to silver nanoparticles

Silver nanoparticle (AgNP) toxicity in eastern oysters, Crassostrea virginica, was investigated in both gill and hepatopancreas tissues, and compared to dissolved Ag exposures. Oysters were exposed to varying concentrations of AgNPs prepared with citrate coatings and dissolved Ag (AgNO₃) for 48 h and the effects on a suite of biomarkers of cellular stress were evaluated. Two biomarkers of cellular damage were evaluated-lysosomal destabilization rates of hepatopancreas cells as indicators of lysosomal damage, and lipid peroxidation as an indicator of oxidative damage. Total glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) assays were used as indicators of impacts on antioxidant capacity. The results indicated that gill tissues were more prone to oxidative damage following dissolved Ag exposures than AgNP exposures, while hepatopancreas tissues were more sensitive to AgNP exposures. Total protein levels increased in hepatopancreas tissues following AgNP exposures, but not dissolved Ag exposures. These tissue specific differences in toxicity and bioreactivity of Ag nanoparticles compared to dissolved metal ions reflect distinct nanoparticle effects. Oysters exposed to dissolved Ag would be more prone to cellular and tissue damage of gills, but oysters exposed to AgNPs could be more prone to hepatopancreas damage contributing to metabolic and reproductive impairment.