title: Biotransformation and Oxidative Stress Responses in Captive Nile Crocodile (Crocodylus niloticus) Exposed to Organic Contaminants from the Natural Environment in South Africa.
abstract: In the present study, the biotransformation and oxidative stress responses in relation to chemical burden in the liver of male and female Nile crocodiles--Crocodylus niloticus--from a commercial crocodile farm passively exposed to various anthropogenic aquatic pollutants was investigated. In general, the data showed that male crocodiles consistently produced higher biotransformation and oxidative stress responses compared to females. Relationships between these responses and concentrations of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were also observed. Specifically, the catalytic assays for EROD and BROD (not PROD and MROD) showed sex-differences between male and female crocodiles and paralleled immunochemically determined CYP1A and CYP3A protein levels; the relatively similar levels of PAHs in both sexes suggest an estrogen-mediated reduction of this pathway in females. The antioxidant system exhibited higher levels in male crocodiles with slight or significant higher values for catalase (CAT), glutathione reductase (GR), glutathione peroxidases-H2O2 (GPx-H2O2), glutathione peroxidases-Cu (GPx-Cu), total antioxidant capacity towards peroxyl radicals (TOSC-ROO) and hydroxyl radicals (TOSC-HO), total glutathione (GSH) and malondialdehyde (MDA). On the other hand, the activities of acyl-CoA oxidase (AOX) and glutathione S-transferases (GST) were significantly higher in females. Principal component analysis (PCA) produced significant groupings that revealed correlative relationships (both positive and negative) between biotransformation/oxidative stress variables and liver PAHs and aliphatic hydrocarbon burden. The overall results suggest that these captive pre-slaughter crocodiles exhibited adverse exposure responses to anthropogenic aquatic contaminants with potentially relevant effects on key cellular pathways, and these responses may be established as relevant species biomarkers of exposure and effects in this endangered species.
authors.affiliation: Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
authors.forename: Augustine
authors.initials: A
authors.lastname: Arukwe
authors.affiliation: Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
authors.forename: Randi
authors.initials: R
authors.lastname: Røsbak
authors.affiliation: Department of Zoology, University of Ibadan, Ibadan, Nigeria.
authors.forename: Aina O
authors.initials: AO
authors.lastname: Adeogun
authors.affiliation: Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
authors.forename: Håkon A
authors.initials: HA
authors.lastname: Langberg
authors.affiliation: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Annette
authors.initials: A
authors.lastname: Venter
authors.affiliation: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Jan
authors.initials: J
authors.lastname: Myburgh
authors.affiliation: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
authors.forename: Christo
authors.initials: C
authors.lastname: Botha
authors.affiliation: Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Maura
authors.initials: M
authors.lastname: Benedetti
authors.affiliation: Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Regoli
mesh_terms: D000489:Alligators and Crocodiles / Q000378:metabolism*; D000818:Animals; D001711:Biotransformation; D002374:Catalase / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004785:Environmental Pollutants / Q000378:metabolism*; D005260:Female; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D008658:Inactivation, Metabolic; D008099:Liver / Q000201:enzymology; D008297:Male; D018384:Oxidative Stress; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D030162:Reptilian Proteins / Q000378:metabolism; D013019:South Africa
chemical_list: D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D030162:Reptilian Proteins; D003577:Cytochrome P-450 Enzyme System; D002374:Catalase; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase