W3 AM Toxicogenomics in Environmental Studies
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in Ballroom 3

(REY-1117-799737) Integration of a custom-made microarray into a multiple effect assessment for cadmium toxicity in Cyprinus carpio.

Reynders, H¹, Van der Ven, K¹, Moens, L¹, Van Campenhout, K¹, Bervoets, L¹, Van Leemput, K¹, De Coen, W², Blust, R¹, ¹ Laboratory of 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- For a better understanding and characterisation of the toxic responses to cadmium and other contaminants in fish it is important to consider sensitive biomarkers that indicate early responses to toxicant exposure. Since reactions at the gene expression level form the basis of most toxicological responses, gene expression analysis provides an excellent method to unravel mechanisms of toxicity and to detect early and sensitive responses to toxicants. The combination of SSH-PCR and microarray technology enables the identification and evaluation of a large set of differentially expressed genes after toxicant exposure in non-model species, such as carp, thereby providing insight in the molecular reactions to toxicant exposure. Integrating gene expression information into a multi-level effect assessment can help to understand and possibly predict effects on higher levels of response. In this study carp (Cyprinus carpio) were simultaneously exposed to different cadmium concentrations via water and food (Tubifex tubifex) to induce genes reflecting both exposure routes. Fish were sampled after 3 hours, 1, 7 and 28 days to detect acute as well as sub-chronic responses. Up- and down regulated genes were isolated using suppression subtractive hybridization-PCR and spotted onto glass-slides to construct a first custom cadmium-related microarray for hepatopancreas tissue in cyprinid fish. Using these microarrays gene expression profiles were obtained for the different concentrations and time-intervals. Sequencing and classification of the differentially expressed genes into functional categories revealed an important role for metal-stress, energy and immune responsive genes. The expression level of a selected subset of the isolated genes was confirmed using semi-quantitative as well as real-time PCR. Finally, the obtained microarray information was integrated in understanding effects at the tissue, physiological and organismal level by measuring critical adverse responses such as decreased alanine transaminase (liver damage) and ion levels in plasma, growth and survival.

Key words: carp, cadmium, microarray, mutiple-effect-assessment