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3A - Biomarker/Biomonitoring (TUP/161) Immunolocalization and quantification of metallothioneins in gills of turbot (Scophthalmus maximus) exposed to cadmium, copper and zinc. Alvarado, Nelva E1, Quesada, Iban1, Hylland, Ketil2, Marigómez, Ionan1, Soto, Manu1, 1 University of the Basque Country, Bilbao, Basque Country, Spain2 Norwegian Institute for Water Research (NIVA), Oslo, Kjelsaas, Norway ABSTRACT- The induction of metallothioneins (MT) in fishes has been employed as exposure biomarker of metal pollution, being quantified through different methods (differential pulse polarography, spectrophotometry, ELISA, etc). In addition, immuocyto(histo)chemistry may allow the in situ localization/quantification of MT. This analytical approach has been hitherto restricted to detect and quantify MT levels in mammals whereas data concerning aquatic organisms are scarce. Recent data suggest the differential expression of MT in selected cell-types in the gills of fishes after exposure to metals. Turbot, Scophthalmus maximus, were exposed to 1 and 10 ppm of Cd, Cu and Zn in order to determine the differential expression of MT in different cell-types of the gills, and to quantify those immunohistochemical levels. Gills were excised after 1 h, and 1 and 7 d of exposure. Samples were fixed in Carnoy and embedded in paraffin to immunolocalize MT (anti-cod MT polyclonal antibody), and to determine the presence of metals by autometallography (as BSD -black silver deposits-) in 5 and 7 Key words: biomarkers, metallothioneins, immunohistochemistry, chloride cells |
m-thick sections respectively. BSD were mainly observed in mucous cells and to a lesser extent in other cell types. The BSD extent quantified by image analysis in mucocytes revealed significant differences between metal exposed and control turbots. MT were mainly localized in chloride cells. MT-levels were significantly higher in metal-exposed fishes and increased with exposure time. This enhanced MT-expression in chloride cells seems to be correlated with an increased cell volume. Concluding, MT-levels in chloride cells and the BSD extent in mucocytes could be considered as reliable biomarkers of metal exposure. *We are indebted to Culmanor SA for kindly supplying turbot. Work funded by the European Commission (BEEP project, EVK3-CT2000-00025).