title: Biotransformation of PCBs in Arctic seabirds: characterization of phase I and II pathways at transcriptional, translational and activity levels.
abstract: Arctic seabirds are exposed to a wide range of halogenated organic contaminants (HOCs). Exposure occurs mainly through food intake, and many pollutants accumulate in lipid-rich tissues. Little is known about how HOCs are biotransformed in arctic seabirds. In this study, we characterized biotransformation enzymes in chicks of northern fulmars (Fulmarus glacialis) and black-legged kittiwakes (Rissa tridactyla) from Kongsfjorden (Svalbard, Norway). Phase I and II enzymes were analyzed at the transcriptional, translational and activity levels. For gene expression patterns, quantitative polymerase chain reactions (qPCR), using gene-sequence primers, were performed. Protein levels were analyzed using immunochemical assays of western blot with commercially available antibodies. Liver samples were analyzed for phase I and II enzyme activities using a variety of substrates including ethoxyresorufin (cytochrome (CYP)1A1/1A2), pentoxyresorufin (CYP2B), methoxyresorufin (CYP1A), benzyloxyresorufin (CYP3A), testosterone (CYP3A/CYP2B), 1-chloro-2,4-nitrobenzene (CDNB) (glutathione S-transferase (GST)) and 4-nitrophenol (uridine diphosphate glucuronyltransferase (UDPGT)). In addition, the hydroxylated (OH-) polychlorinated biphenyls (PCBs) were analyzed in the blood, liver and brain tissue, whereas the methylsulfone (MeSO(2)-) PCBs were analyzed in liver tissue. Results indicated the presence of phase I (CYP1A4/CYP1A5, CYP2B, and CYP3A) and phase II (GST and UDPGT) enzymes at the activity, protein and/or mRNA level in both species. Northern fulmar chicks had higher enzyme activity than black-legged kittiwake chicks. This in combination with the higher SigmaOH-PCB to parent PCB ratios suggests that northern fulmar chicks have a different biotransformation capacity than black-legged kittiwake chicks.
authors.affiliation: Norwegian Polar Institute, 9296 Tromsø, Norway. Lisa.Helgason@npolar.no
authors.forename: Lisa B
authors.initials: LB
authors.lastname: Helgason
authors.forename: Augustine
authors.initials: A
authors.lastname: Arukwe
authors.forename: Geir W
authors.initials: GW
authors.lastname: Gabrielsen
authors.forename: Mikael
authors.initials: M
authors.lastname: Harju
authors.forename: Marit N
authors.initials: MN
authors.lastname: Hegseth
authors.forename: Eldbjørg S
authors.initials: ES
authors.lastname: Heimstad
authors.forename: Even H
authors.initials: EH
authors.lastname: Jørgensen
authors.forename: Anne S
authors.initials: AS
authors.lastname: Mortensen
authors.forename: Johannes
authors.initials: J
authors.lastname: Wolkers
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001110:Arctic Regions; D001711:Biotransformation / Q000235:genetics; D001717:Birds / Q000235:genetics / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D003577:Cytochrome P-450 Enzyme System; D011078:Polychlorinated Biphenyls