Toxicogenomic Responses to Inorganic and Organic Mercury in Caenorhabditis elegans

Humans are exposed to both inorganic and organic mercury. While the toxicity of mercury is well established, much remains to be resolved about how different mercurials act at the molecular level. To address this issue, we employed a toxicogenomics approach using the nematode C. elegans. Using sub-, low- or high-toxic exposures of either HgCl2 or CH3HgCl the effects of these mercurials on steady-state mRNA levels for the entire genome were determined. A total of 473 and 2,865 genes were differentially expressed in the HgCl2 and CH3HgCl treatments, respectively. Hierarchical clustering, principal components and pattern analyses indicated that the transcriptional responses of the mercurials were unique. Mixed-stage C. elegans populations were exposed to 0, 2, 7.5 or 20 uM HgCl2 or 0, 0.75, 2, 7.5 uM CH3HgCl for 24 hours. Three independent experiments were performed for each treatment condition.