DEVELOPMENT OF A RAPID AND SIMPLE GENOTOXICITY ASSAY USING A BROWN BULLHEAD FISH CELL-LINE - APPLICATION TO TOXICOLOGICAL SURVEYS OF SEDIMENTS IN THE HURON-ERIE CORRIDOR

This study calibrates the use of a bullhead cell line as a measure of contaminant stress by measuring cyto- and genotoxicity of sediment extracts from the Detroit and St. Clair rivers. A simple and rapid method was developed using established cell cultures of brown bullhead that measures the level of DNA repair as an indicator of genotoxicity. The level of unscheduled DNA synthesis (UDS) was quantified by measuring the incorporation of labeled thymidine into DNA. We used this assay coupled with a neutral red dye uptake assay to test sediment extracts from three sites: Trenton Channel (TR) and Turkey Island (TI) in the Detroit River and Channel Ecart (CE) in the St. Clair River. The samples from each site were extracted and fractionated into two main groups of chemicals, organochlorinated compounds (OCCs, fraction 1) and polycyclic aromatic hydrocarbons (PAHs, fraction 2). The neutral red assay showed that the TR extracts were consistently more cytotoxic than the TI and CE extracts, with no significant differences between the cytotoxic effects of extracts from the TI and CE. The OCCs and PAHs from each site interacted in a synergistic manner to deleteriously affect cell viability. Based on the DNA repair assay, the TR (fractions 1 and 2) extracts were the most genotoxic compared with extracts from the other two sites. Significant synergistic interactions between the two groups of chemicals from each of the three sites were observed resulting in the induction of higher levels of UDS. In conclusion, the brown bullhead fish cell line was shown to have the potential to be a model system for assessing biological effects of in place pollutants using a dye-uptake cytotoxicity assay and a simple and rapid genotoxicity assay.