WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: MS2381
Title: Screening of Environmental Contaminants Detected in Mississippi Sediments as Inducers and/or Inhibitors of CYP1B1 Expression in Channel Catfish
Focus Categories: Toxic Substances, Agriculture
Keywords: Bioindicator, Toxic Substances, Pesticides
Start Date: 03/01/2001
End Date: 02/28/2002
Federal Funds: $20,047
Non-Federal Matching Funds: $40,094
Congressional District: Third
Kristine L. Willett
Assistant Professor, The University of Mississippi
Sediments associated with Mississippi rivers and lakes contain significant concentrations of environmental contaminants including pesticides and industrial by-products. Chemical characterization of these complex mixtures is often expensive and incomplete. Certain cytochrome P450 enzymes such as CYP1A have been developed as biomarkers of exposure in fish and wildlife. These physiological endpoints integrate exposure to several types of contaminant, are cheaper than analytical analyses, and are indicative of bioavailable contaminants. Biomarker methodologies are critical in order to detect toxic insult at sublethal exposures so that individuals, population and community structure are not affected by contamination of Mississippi waterways. This project is specifically aimed at characterizing the utility of a recently discovered cytochrome, CYP1B1, as a marker of exposure to contaminants that have been reported by the USGS NAWQA and BEST programs in Mississippi sediments and fish samples. Because channel catfish are such an abundant and economically significant species in Mississippi, they will be used as the test organism in these studies.
Using primary cultured channel catfish liver hepatocytes to screen a series of diverse contaminants including polychlorinated biphenyls, polycholorinated dibenzo-p-dioxins, polycyclic aromatic hydrocarbons and organochlorine pesticides, the inducibility and/or inhibition of CYP1B1 will be tested. For compounds that indicate in vitro inducibility, we will conduct in vivo exposures to characterize the in vivo time course and dose response relationships in channel catfish. Ultimately, we will characterize the in situ utility of CYP1B1 as a biomarker of exposure to contaminated sediment in channel catfish collected from Mississippi lakes and rivers. This project has the potential to develop an entirely new physiological endpoint of contamination in fish. Because of its role in carcinogenesis, insight into the mechanisms of CYP1B1 induction across taxa will be a significant advance toward applications of CYP1B1 status as a marker for environmental contaminants and potentially cancer.