Biomarkers of oxidative stress and genotoxicity in livers of field-collected brown bullhead, Ameiurus nebulosus

The objective of this investigation was to determine whether differences in a suite of biomarker assays in brown bullhead liver tissues could be detected and related to the pollution histories of two Ohio locations, one a reach of the Black River that had historically been severely impacted by the effluents of a coking plant, the other at Old Woman Creek, a freshwater estuarine research preserve. There were no gross differences in pathologies detectable in fish from either site, and the major difference found in bullheads at the two sites was in the relative Liver weight (RLW). Differential responses of glutathione reductase, glutathione-S-transferase, Se-dependent glutathione peroxidase, Se-independent glutathione peroxidase, and oxidized glutathione have been reported between fish from contaminated and uncontaminated sites in other studies, but no such differences were observed in the present study. Of the oxidative stress biomarkers included in this investigation, only the responses of superoxide dismutase, catalase, and total glutathione appeared to correlate with environmental exposure of brown bullhead to polycyclic aromatic hydrocarbons. Results with single-strand DNA and ethoxyresorufin-o-deethylase were the reverse of what has been reported in most other studies, and may reflect adaptation of the fish at the previously highly contaminated site. The fish at the:Black River site appear to have responded to the xenobiotics present in their environment by increasing their overall liver size, thereby increasing the overall amount of enzymes rather than altering the specific activity of a select set of protective enzymes.