HA4 Ecotoxicogenomics
204 Oregon Ballroom
8:00 AM - 12:00 PM, Thursday
() Gene expression links to endocrine function and reproduction decline after mercury exposure in fathead minnows.
Klaper, R1, Carvan, M1, Dasmahapatra, A2, Weber, D1, Drevnick, P3, Sandheinrich, M4, 1 University of Wisconsin-Milwaukee, Milwaukee, WI, USA2 University of Mississippi, University, MS, USA3 Miami University, Oxford, OH, USA4 University of Wisconsin-La Crosse, La Crosse, WI, USA
ABSTRACT- Genomics provides a new level of investigation for traditional toxicological studies, however there is a need to link gene expression data to important endpoints, for ecotoxicology in particular. The purpose of this study was to identify changes in gene expression associated with mercury exposure (methylmercury), and specifically those associated with previously observed changes in reproduction and reproductive biomarkers. In addition we attempted to identify differential gene expression of genes involved in other physiological pathways with either known or suspected dysfunction connected with mercury exposure. Fathead minnows Pimephales promelas were fed diets containing either control, low or medium levels (0.06, 0.87, or 3.93 ug/g dry weight respectively) of methylmercury from 90 days post-hatch until after spawning. Liver, gonad and brain tissues were collected and RNA isolated from each individual fish and tissue. Suppressive subtractive hybridization of medium dose versus control for pooled liver and gonad tissues indicated potential changes in the expression of several hundred genes with exposure. A subset of the genes of interest was available on a commercial liver array for fathead minnow, which was used to examine gene expression in individual liver samples. Differences in gene expression were confirmed using QPCR. In addition, several genes identified in the subtraction process that were not available on the array were also investigated using QPCR for individual liver and gonad tissue from all three treatments. Genes associated with immune response and nervous system function, and reproduction, including egg fertilization and development, differ in levels of expression with mercury exposure. Significant differences in expression patterns between male and female fish were also observed. A previously published study on same population of fish demonstrated a decrease in fertility and changes in levels of testosterone and estradiol (E2) with mercury exposure. Potential links between reproduction, biomarkers and molecular indicators are discussed.
Key words: endocrine disruption, mercury, ecotoxicogenomics, gene expression