Methodology article

Gene expression profiling to characterize sediment toxicity – a pilot study using Caenorhabditis elegans whole genome microarrays

Ralph Menzel^1†, Suresh C Swain^2†, Sebastian Hoess³, Evelyn Claus⁴, Stefanie Menzel¹, Christian EW Steinberg¹, Georg Reifferscheid⁴ and Stephen R Stürzenbaum^2*

• * Corresponding author: Stephen R Stürzenbaum stephen.sturzenbaum@kcl.ac.uk

• † Equal contributors

Author Affiliations

¹ Humboldt-Universität zu Berlin, Department of Biology – Freshwater and Stress Ecology, Spaethstr. 80/81, 12437 Berlin, Germany

² School of Biomedical & Health Sciences, Pharmaceutical Science Division, King's College London, 150 Stamford Street, London, SE1 9NH, UK

³ Ecossa (ecological sediment & soil assessment), Giselastr. 6, 82319 Starnberg, Germany

⁴ Federal Institute of Hydrology, Department Biochemistry and Ecotoxicology, Am Mainzer Tor 1, 56068 Koblenz, Germany

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BMC Genomics 2009, 10:160 doi:10.1186/1471-2164-10-160

Published: 14 April 2009

Abstract

Background

Traditionally, toxicity of river sediments is assessed using whole sediment tests with benthic organisms. The challenge, however, is the differentiation between multiple effects caused by complex contaminant mixtures and the unspecific toxicity endpoints such as survival, growth or reproduction. The use of gene expression profiling facilitates the identification of transcriptional changes at the molecular level that are specific to the bio-available fraction of pollutants.

Results

In this pilot study, we exposed the nematode Caenorhabditis elegans to three sediments of German rivers with varying (low, medium and high) levels of heavy metal and organic contamination. Beside chemical analysis, three standard bioassays were performed: reproduction of C. elegans, genotoxicity (Comet assay) and endocrine disruption (YES test). Gene expression was profiled using a whole genome DNA-microarray approach to identify overrepresented functional gene categories and derived cellular processes. Disaccharide and glycogen metabolism were found to be affected, whereas further functional pathways, such as oxidative phosphorylation, ribosome biogenesis, metabolism of xenobiotics, aging and several developmental processes were found to be differentially regulated only in response to the most contaminated sediment.

Conclusion

This study demonstrates how ecotoxicogenomics can identify transcriptional responses in complex mixture scenarios to distinguish different samples of river sediments.