An integrated approach of multiple 'omics' techniques for the detection of ecologically relevant biomarkers for Daphnia magna.

Daphnia magna, a frequently used standard organism in laboratory toxicity testing was chosen for this study. In laboratory toxicity testing it is often assumed that organisms will respond in a similar manor as in a field situation. However, in realistic environments multiple factors and stressors, such as the differences in temperature, food availability, etc.... may strongly interfere with responses to pollutant stress. Moreover, organisms are almost always exposed to mixtures of chemical stressors in natural situations. From a toxicological point of view, these interactions can highly influence the overall impact of chemical stressors.

In the present study, the impact of a combination of stressors (biotic and abiotic) on Daphnia magna will be evaluated. The individual compounds as well as the binary mixtures of several similarly and dissimilarly acting compounds will be assessed at different levels of biological organization. In a first stage dissimilarly acting compounds (nickel and chlorpyrifos) were assesed using microarray analysis in combination with different other biomarkers such as Energy Allocation and growth. In a later phase effects of differences in temperature on nickel toxicity were evaluated on these endpoints. The latter study was performed in collaboration with Dr.Susana Loureiro from the University of Aveiro. And in yet another part two similarly acting compounds were selected (fluoranthene and pyrene)for evaluation of the gene expression patterns,CEA and metabolomics analysis. The metabolomics part was performed in collaboration with Dr. Oliver Jones and Dr. Julian Griffin from the University of Cambridge. This study is part of the European NoMiracle project (Novel Methods for Integrated Risk Assessment of Cumulative Stressors in Europe).