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Evaluation of the genomic effects of four environmentally suspect pharmaceutical compounds on Atlantic salmon

Final Activity Report Summary - SALMONPHARM (Evaluation of the genomic effects of four environmentally suspect pharmaceutical compounds on Atlantic salmon.)

Environmental stressors exert their toxic effects on exposed non-target organisms by producing an impairment of normal cellular functions which, depending on the duration and concentration of the exposure, may lead to physiological damage. One group of compounds found in increasing concentrations in the environment are pharmaceutics that are used in human and veterinary medicine. The concern over pharmaceuticals has recently emerged and they are now considered as possible candidates for introduction into the Water Framework Directive list of priority substances (2000/60/EC).

Once these compounds are, the original compound or its metabolites are excreted and reach sewage systems and receiving water bodies where they might exert effects on non-target organisms, either through the effects of the original compounds, or by unknown effects of metabolites. Concentrations at µ*L-1 levels have been found in waste water treatment influents and effluents and could thus enter surface waters.

Juveniles of Atlantic salmon, namely salmo salar, were exposed to environmentally relevant concentrations of four of the most representative pharmaceutical compounds in order to evaluate the effects and the environmental impact of pharmaceutical waste that was present in aquatic environments. These compounds included the analgesic, i.e. pain reliever, and antipyretic, i.e. fever reducer, acetaminophen, the anti-depressive and antiepileptic drug carbamazepine, the beta-blocker atenolol and the antibiotic trimethoprime. The effects were evaluated at the level of altered gene, i.e. transcriptomics, and protein, i.e. proteomics, expression in different target tissues, such as liver and brain, of the exposed organisms by means of complementary deoxyribonucleic acid (cDNA) microarray hybridisation and two-dimensional differential gel electrophoresis (DIGE) techniques.

The expression profiling revealed the up-or down-regulation of numerous features involved in various physiological pathways, some of which were exclusive for the different selected treatments. The detailed physiological significance of these genetic or proteomic changes had still to be determined in most of the cases, however it was clear that a deviation from normal functioning implied the use of energetic resources which, under non-exposure circumstances, would be employed in, for example, feeding and growth. Such changes could reduce the fitness of exposed organisms. Furthermore they enabled the identification of highly altered expression features for the different treatments that would be useful for the development of contaminant-specific biomarkers as tools for environmental risk assessment.