engleski

Interpretation of natural fluctuations of metallothioneins and metal levels in the aquatic organisms

Metallothionein (MT) is established as a biomarker of metal exposure of aquatic organisms. In different tissue types, like gills, liver, kidney, intestine, of the aquatic organisms the levels of MT are related to the cytosolic metal concentrations (Zn, Cu, Cd) that induce the MT synthesis. Exposure of the aquatic organisms (shellfish and fish) under the controlled conditions clearly indicates de nuovo MT synthesis, but those experiments are performed at elevated metal levels that are usually not relevant for environmental conditions. In the field studies, fluctuations of different magnitude are observed for MT and cytosolic metal concentrations. They reflect individual response of the organism to different abiotic and biotic conditions, e.g. food availability, age, reproductive cycle etc. Therefore, within the overall MT concentration at the cellular level, the contribution of natural (biotic and abiotic) parameters to the basal level of MT and cytosolic metals, has to be defined before interpreting the results as being affected by metal pollution. Field studies conducted on indigenous fish and shellfish will be illustrated and discussed with respect to the limitations of using MT as the biomarker of metal pollution, in the indigenous aquatic organisms. References: V. Filipović Marijić and B. Raspor (2007) Metal exposure assessment in native fish, Mullus barbatus L., from the Eastern Adriatic Sea, Toxicology Letters: 168(292-301). B. Raspor, Z. Dragun, M. Erk, D. Ivanković and J. Pavičić (2004) Is the digestive gland of Mytilus galloprovincialis a tissue of choice for estimating cadmium exposure by means of metallothioneins?, Science of the Total Environment: 333(99-108).

Biomarker of metal exposure; metallothionein; auqatic organisms

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