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(22-21) Fluorimetric measurement of EROD activity. Caution about the spectral characteristics of the standards used. Radenac, Gilles1, Coteur, Geoffroy2, Danis, Bruno2, Dubois, Philippe2, Warnau, Michel*,2,3, 1 Lab. de Biologie & Environnement Marins- EA 3168 - Univ. La Rochelle - Institut de la Mer - Quai Lazaret - Port des Minimes, La Rochelle, France2 Laboratoire de Biologie Marine, Université Libre de Bruxelles - Av. F.D. Roosevelt, Brussels, Belgium3 IAEA - Marine Environment Laboratory, 4 Quai Antoine Ier, BP 800, Monaco, Principality of Monaco ABSTRACT- The activity of the enzyme 7-ethoxy-resorufin-O-deethylase (EROD) has been widely used in biomonitoring studies for more than a decade. Although the analytical procedure for this activity is quite simple, it is often poorly characterised. In this study, spectral properties of particular standard compounds used for EROD activity measurement (viz. ethoxyresorufin - EthR - and resorufin - Res-, standards from Molecular Probes) were tested in order to optimise excitation and emission wavelengths to be used in the fluorimetric assay of EROD activity. The optimal excitation wavelength for the detection of Res was found to be 560 nm. Indeed, at this wavelength, the excitation represents only 37% of its maximum level for EthR while it represents 86% for Res. This allows to discriminate between the fluorescence emitted by both standards favouring the formed product (Res). Our results demonstrate that any analytical work using spectrofluorometry to measure EROD activity should be preceded by a precise determination of the spectral characteristics of each set of standards used. Key words: EROD measurement, spectral characteristics, fluorimetry, biomarker |
