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(22-35) Metallothioneins in the mussel Mytilus galloprovincialis and their use as biomarker for heavy metal pollution. Menge, S.1, Miersch, J.1, Krauss, G.-J.1, Chafik, A.2, Benhra, A.2, Elamrani, M.K.3, Elghazi, I.*,1,3, 1 Martin Luther University, Dep. Biotechnology/Biochemistry, Halle, Germany2 INRH, Ecotoxicology laboratory, Casablanca, Morocco3 Hassan II University, Casablanca, Morocco. ABSTRACT- Aquatic ecosystems are more and more exposed to hazard pollution of different kind of chemicals. To evaluate and control this pollution, the chemical analyses are necessary but not sufficient. They give information about the rate of these pollutants in the compartments of the aquatic ecosystems (sediment, water and biota), but do not give information about the effect of this pollution on ecosystem. Organisms are in fact exposed to a very complex mixture of pollutants, which exert most of the time a chronic pollution. Biochemical manifestations such as stress enzymes (CYP450, Acetylcholinesterase, GSH-S-transferase, GSH-synthetase) and stress proteins (Metallothioneins, MTs) are the first perturbations generated by pollutant toxicity. MTs are low molecular weight proteins (6-7 kDa), with high cysteine contents (30%). They are inducible by both essential (Cu, Zn) and toxic (Cd, Hg) metals. Due to high -SH contents, they allowed the organisms to regulate the cellular metal homeostasis and to reduce the toxicity of the nonessential. The biomonitoring program for the Moroccans coast uses the mussels Mytilus galloprovincialis and Perna perna as bioindicator organisms for heavy metal pollution. Because of their feed mode through a water filtration, these organisms are able to accumulate high amounts of contaminants including heavy metals. The aim of this work is the adaptation of a rapid method for the detection and quantification of MTs, in order to use it for the heavy metal screening of marine coasts. Pre-purified MTs were prepared, using a two-step solvent precipitation, from Cd-exposed or unexposed mussels. Methods of capillary zone electrophoresis, RP-HPLC and direct spectrophotometry were developed and proved for their suitability in screening programs. Key words: Metallothioneins, Biomarker, Mussels, Cadmium |
