Application of transcriptomics in advancing our understanding of chemical effects and their potential impact in fish - A practical demonstration.

Very significant quantities of man-made chemicals end up in the aquatic environment via (treated) wastewater effluents, many of which have been shown to possess endocrine disrupting activity. Studies conducted in the UK have identified wastewater effluents as major points of entry for endocrine disrupting chemicals (EDCs) with oestrogenic activity. Feminisation of fish occurs in rivers receiving high levels of wastewater effluents and recent studies in our laboratory with roach have demonstrated that exposure to environmental relevant concentrations of some of these chemicals with oestrogenic activity for prolonged periods in their life can result in complete feminisation of whole populations. It is important to understand the mechanistic basis for the disruption caused by environmental chemicals with endocrine activity, in order to better determine safety thresholds for their discharge into the environment and for identifying biomarkers that are able to predict for adverse effects before the ecosystem is damaged. There is a need for effective tools that can be employed to screen chemicals and classify these based on their mode-of-action. In this context, we developed a genome-wide 44k Agilent microarray to quantify gene expression profiles in the fathead minnow (Pimephales promelas), one of the OECD recommended test species and widely used in ecotoxicology. Transcriptomics data generated in a pilot study demonstrated the quality and accuracy of this newly developed microarray and its potential as a tool for chemical testing and screening. The first major component of this KT proposal will provide a comprehensive, user friendly, genomic resource database for the fathead minnow, that will be an invaluable tool for researchers using the fathead minnow as a model species (for both fundamental and ecotoxicology studies), but also for comparative biology employing genomic approaches. Secondly, the project will provide a key practical example of how transcriptomics can be used to advance our understanding of chemical effects and their potential impact in fish (as a sentinel for pollution in the aquatic environment). Finally, this KT project will disseminate knowledge and technical capability on transcriptomics to industry, regulators and the wider public via a workshop to be held at the University of Exeter.