Student Research: Clint Farr

, , 1998
Faculty Advisor: Elaine M. Faustman

Gene Expression as a Biomarker of Mercury Exposure in Raccoons from the Savannah River Nuclear Weapons Facility


While biomarkers have been proposed as a tool in assessing ecological risk, few have been developed. One avenue of biomarker research involves determining altered gene expression due to xenobiotic exposure. Altered gene expression may provide information on exposure as well as early biological effect. We examine the use of altered gene expression in a sentinel species, raccoon, as a biomarker of exposure to and effect from mercury. Raccoons (Procyon lotor) are an ideal sentinel species because they are omnivorous, occur over most of North America, and are potentially exposed to multiple contaminants and stressors.

Liver and kidney were collected from raccoons on the Savannah River Site. The collection is part of a project with the Environmental and Occupational Health and Safety Institute (EOHSI), New Jersey, and the Savannah River Ecology Laboratory. In the summer of 1997, tissues from 17 raccoons taken from a contaminated area with elevated soil mercury and from 41 raccoons from control areas, were analyzed for mercury content at EOHSI. These tissues were analyzed for changes in expression of metal and stress response genes at the University of Washington.

The utility of gene expression as a biomarker of mercury exposure and effect was examined by correlating organ mercury levels with altered mRNA expression of mercury inducible genes. Using results from Reverse Northern and Northern analysis, this work will be useful for establishing biomarkers of mercury exposure in wildlife species, reducing uncertainty surrounding mercury exposure and effect in ecological risk assessments, and elucidating mechanisms of mercury toxicity.

This research is supported by CRESP through the department of Environmental Health cooperative agreement #DE-FC01-95EW55084.