Although cadmium toxicity is a well studied theme in the field of aquatic toxicology, still little is known concerning the molecular mechanisms of its toxic action. Moreover most laboratory studies only consider waterborne cadmium exposure, whereas dietary exposure can also contribute to the accumulation and effects of cadmium in fish. For a better understanding of the toxic responses leading to adverse effects there is an increasing need for more sensitive tools to determine early reactions on cadmium exposure and accumulation.
Since gene expression can be considered as the basis of many toxicological responses, gene expression analysis provides an excellent method to elucidate the mechanisms of toxic action and to detect toxic effects in a fast and sensitive way. SSH-PCR (Suppression Subtractive Hybridisation-PCR) combined with microarray technology offers an excellent tool to detect genes that are differentially expressed after metal exposure and to evaluate their expression in different exposure scenario’s.
In this project the influence of time and exposure concentration on the accumulation and effects of cadmium in carp, Cyprinus carpio , is investigated. For these goals a combination of SSH-PCR and microarray technology is applied to construct a microarray for gene expression evaluation in liver tissue. In addition, cDNA normalization is used to extend the array with genes from gill and kidney tissue. These arrays are used to characterize the impact of concentration and time of exposure on the molecular level. A second important goal is the study of the relative importance of water and food for the accumulation and gene expression changes. Finally the developed arrays will be applied in field studies, in which both caged carp and resident fish will be studied. In addition, the observed gene expression reactions will be integrated into a characterization of effects at different levels of response, such as disturbance of the ion homeostasis, liver damage, growth and mortality.
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