Physiological, morphological and metabolic changes in Tetrahymena pyriformis for the in vivo cytotoxicity assessment of metallic pollution: Impact on D-b-hydroxybutyrate dehydrogenase Driss Mountassif a, * , Mostafa Kabine a , Rachid Manar b , Noureddine Bourhim a , Zaina Zaroual c , Norbert Latruffe d , M’Hammed Saı ¨d El Kebbaj a a Laboratoire de Biochimie et Biologie Mole ´culaire, Faculte ´ des Sciences, Universite ´ Hassan II-Aı ¨n Chock, km 8 route d’El Jadida BP. 5366 Casablanca, Morocco b Laboratoire de Biologie et Ecologie Animale, Faculte ´ des Sciences, Universite ´ Hassan II-Aı ¨n Chock, km 8 route d’El Jadida BP. 5366 Casablanca, Morocco c Laboratoire d’Electrochimie et Chimie de l’Environnement, Faculte ´ des Sciences, Universite ´ Hassan II-Aı ¨n Chock, km 8 route d’El Jadida BP. 5366 Casablanca, Morocco d LBMC (GDR-CNRS no. 2583), Faculte ´ des Sciences, 6 Bd Gabriel, Universite ´ de Bourgogne et Centre de Recherche INSERM, Faculte ´ des Sciences, 21000 Dijon Cedex, France Received 30 July 2006; received in revised form 19 November 2006; accepted 20 November 2006 Abstract The individual cytotoxicity of cadmium chloride, iron sulphate and chromium nitrate has been investigated by using the freshwater ciliate Tetrahymena pyriformis. The metabolic enzymes and antioxidant defense biomarkers were assessed. The results obtained reveal that their metal salts have perturbed the physiology and morphology of T. pyriformis. Also, the biomarkers assessed were sensitive to the presence of metal salts and this sensitivity was metal salt and dose dependant. To estimate the impact of their metal salts on mitochondria, we studied their effects in vivo and in vitro on the D-b-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30) inner mitochondrial membrane enzyme. The results showed a high inhibition of BDH in terms of activity, protein expression and kinetic parameters. # 2006 Elsevier Ltd. All rights reserved. Keywords: Tetrahymena pyriformis; Cytotoxicity; Metal salts; Metabolic enzymes; Antioxidant biomarkers; Mitochondria; D-b- hydroxybutyrate dehydrogenase This article is also available online at: www.elsevier.com/locate/ecolind Ecological Indicators 7 (2007) 882–894 Abbreviations: BDH, D-b-Hydroxybutyrate dehydrogenase; DL-BOH, DL-b-Hydroxybutyrate; DCIP, Dichloroindophenol; DTNB, Dithio- nitrobenzene; DTT, Dithiotreitol; EDTA, Ethylenediamine tetraacetic acid; D-G3P, D-glyceraldehyde-3-phosphate; KCN, Potassium cyanide; MDA, Malondialdehyde; NAD(H), Nicotinamide adenine dinucleotide oxidized (reduced) forms; NADPH, Nicotinamide adenine dinucleotide phosphate reduced form; PMSF, Phenylmethylsulphonylfluoride * Corresponding author. 1470-160X/$ – see front matter # 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ecolind.2006.11.010