1/10 LC50 metal exposures to Daphnia magna

ABSTRACT: Background: Toxicogenomics provides new opportunities for innovative and proactive approaches to chemical screening, risk assessment, and predictive toxicology. If applied to ecotoxicology, genomics tools could greatly enhance the ability to detect toxicants and understand the modes of toxicity in an environmental setting. However, few studies have yet to illustrate the potential of genomic techniques in ecotoxicology. Objective: Therefore, our objective was to demonstrate the potential utility of gene expression profiling in ecotoxicology using Daphnia magna, a standard aquatic ecotoxicity test organism. Methods: D. magna were exposed to copper, cadmium, and zinc at the 1/10 LC50 for 24 hours. Following each exposure, RNA was isolated, reverse transcribed, and the cDNA was hybridized to a 5000 clone cDNA microarray for D. magna. Differentially expressed cDNAs were sequenced and homology searches revealed each gene product's potential function. Real time PCR was used to verify the differential expression of several genes, and enzyme assays were used to assess the significance of these changes. Results: We identified distinct expression profiles in response to acute copper, cadmium, and zinc exposures and discovered specific biomarkers of exposure including two probable metallothioneins, and a ferritin mRNA with a functional IRE. The gene expression patterns support known mechanisms of metal toxicity and reveal novel modes of action including zinc inhibition of chitinase activity. Conclusions: Using a cDNA microarray for traditional ecotoxicology organism, D. magna, we have identified novel biomarkers of exposure and revealed possible modes of toxicity, providing experimental support for the utility of ecotoxicogenomics. Keywords: comparative toxicant exposure

ORGANISM(S): Daphnia magna

PROVIDER: GSE4759 | GEO | 2006/12/22

SECONDARY ACCESSION(S): PRJNA95571

REPOSITORIES: GEO