Biomarkers of exposure to nanosilver and silver accumulation in yellow perch (Perca flavescens)

There is a risk of exposure of aquatic organisms to nanosilver (AgNP) from discharges of municipal and industrial wastewater. In the present study, yellow perch (Perca flavescens) were exposed in static-renewal experiments conducted over 96 h and 10 d to environmentally relevant concentrations (i.e. 1 and 100 µg/L) of AgNP and Ag+. The greatest accumulation of total silver (tAg) occurred in the liver of P. flavescens and there was >10-fold more accumulation in the treatments with Ag+ relative to the AgNP treatments. Residues of tAg increased with concentration and duration of exposure in liver, gill and muscle. Both exposures caused a 2-fold induction of gene expression for metallothionein (mt) in liver tissue after 96 h of exposure, and reductions in levels of oxidized glutathione (GSSG) in liver after 10 d of exposure. Both AgNP and Ag+ decreased the expression of heat-shock proteins (hsp70). Exposure to the high concentration of AgNP for 10 d significantly increased lipid peroxidation in gill tissue, as indicated by the thiobarbituric acid reactive substances (TBARS) assay. There was a negative correlation between mean levels of GSSG and TBARS for both gill and liver tissue when data for all treatments were combined. It is significant that these biological responses were observed in P. flavescens exposed to AgNP, even though accumulation of tAg was at least 10-fold lower relative to the treatments with Ag+. This article is protected by copyright. All rights reserved