MP7 Toxicogenomics in Environmental Studies
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(VAN-1117-824415) Single and combined effects of organophosphate pesticides and nickel through microarray analysis in Daphnia magna.

Vandenbrouck, T¹, Soetaert, A¹, van der Ven, K¹, Moens, L¹, Naudts, B², Blust, R¹, De Coen, W¹, ¹ Laboratory for Ecophysiology, Biochemistry and Toxicology, Department of Biology, University of Antwerp, Antwerp, Belgium² Intelligent System Lab, Department of Mathematics and Informatics, University of Antwerp, Antwerp, Belgium

ABSTRACT- Daphnia magna is frequently used as a standard organism in laboratory toxicity testing in order to assess the potential hazards of chemicals to the aquatic environment. In this context, it is often assumed that laboratory populations of organisms will respond identically towards a certain contaminant as field populations. However, other factors such as acclimation, adaptation and present environmental conditions may produce differences in tolerance and/or sensitivity between laboratory and field-collected populations. For instance, in natural communities, additional stresses such as the presence of predators may strongly interfere with responses to pollutant stress. Moreover, relevant environmental conditions are usually characterized by the presence of multiple chemical stressors. From a toxicological point of view, these interactions can highly influence the overall impact of chemical stressors. In the present study, we evaluated the impact of multiple chemicals on D. magna using microarray analysis. In addition, multiple biomarkers were measured (Acetylcholinesterase, Cellular Energy Allocation) as well as effects on growth. Two organophosphate pesticides (chlorpyrifos, diazinon) and nickel were assessed as individual compounds and as binary mixtures. Differential gene expression was assessed using a custom cDNA microarray containing genes related to energy metabolism, molting and reproduction. Insights concerning the specific modes of action of the individual compounds and of the mixtures were gained. The potential of microarray analysis for the evaluation of mixture toxicity was assessed.

Key words: Toxicogenomics, Microarray, Daphnia magna, Mixtures