B[a]P–DNA binding in early life-stages of Atlantic tomcod: population differences and chromium modulation

Atlantic tomcod (Microgadus tomcod) from the Hudson River (HR) are resistant at the molecular and organismic levels to the effects of exposure to dioxin-like aromatic hydrocarbon (AH) compounds, but much less so to benzoa]pyrene (Ba]P). The aims of this study were to determine in early life-stages of tomcod exposed to Ba]P: (1) if DNA binding levels differed between fish from the HR and Miramichi River (MR), and (2) if co-exposure to chromium could modulate this genotoxic effect. After exposure to ³H]Ba]P alone, DNA-bound radioactivity was 5–10-fold higher in embryos and larvae of MR than HR descent. Co-exposure to chromium modulated DNA binding levels in offspring of both populations. In MR embryos, co-exposure to chromium inhibited Ba]P uptake. These results demonstrated resistance to the genotoxic effects of Ba]P in early life stages of HR tomcod at an ecologically important endpoint and suggest the ability of chromium to modulate AH-induced genotoxicity.