title: Evaluation of the gill filament-based EROD assay in African sharptooth catfish (Clarias gariepinus) as a monitoring tool for waterborne PAH-type contaminants.
abstract: The ability of African sharptooth catfish (Clarias gariepinus) in inducing cytochrome P-450 class 1A (CYP1A) and glutathione S-transferase (GST) biomarkers was determined in liver and gill filaments after 4 days of waterborne exposure to the polycyclic aromatic hydrocarbon, benzo[a]pyrene (B[a]P). Male (n=6) and female (n=6) fish were exposed to B[a]P added to the water (30 microg/l) corresponding to 5 mg/kg total body weight. Five female and six male fish, exposed to acetone alone added to the water served as controls. The 7-ethoxyresurufin-O-deethylase (EROD) activity was measured in hepatic microsomes and gill filaments. In addition, GST activity was determined in the hepatic cytosolic fraction and fluorescent aromatic compounds (FACs) in bile and biliverdin. Benzo[a]pyrene strongly induced EROD activities in gill filaments of both sex. Levels of FACs per ml of bile were 17-fold higher in exposed fish compared to the controls. Correlations between induction of EROD activities in gill filaments and liver and between induction of EROD activities in gill filaments and levels of biliary FACs metabolites were strong. GST activities in the hepatic cytosolic fraction were similar amongst the treated and control groups. This is the first report on studies determining EROD activities in gill filaments and hepatic tissue, FACs in bile and GST in hepatic tissues of C. gariepinus after waterborne exposure to B[a]P. The findings suggest that the gill filament-based EROD assay in C. gariepinus can be used to monitor the pollution of AhR agonists in aquatic ecosystems in eastern and southern African countries.
authors.affiliation: Department of Veterinary Medicine and Public Health, Faculty of Veterinary Medicine, Sokoine University of Agriculture, P.O. Box 3021, Morogoro, Tanzania. rmdegela@yahoo.com
authors.forename: Robinson
authors.initials: R
authors.lastname: Mdegela
authors.forename: Jan
authors.initials: J
authors.lastname: Myburgh
authors.forename: Dacia
authors.initials: D
authors.lastname: Correia
authors.forename: Marte
authors.initials: M
authors.lastname: Braathen
authors.forename: Francis
authors.initials: F
authors.lastname: Ejobi
authors.forename: Christo
authors.initials: C
authors.lastname: Botha
authors.forename: Morten
authors.initials: M
authors.lastname: Sandvik
authors.forename: Janneche Utne
authors.initials: JU
authors.lastname: Skaare
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry; D001681:Biological Assay; D015415:Biomarkers; D002397:Catfishes; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D004784:Environmental Monitoring; D005260:Female; D005880:Gills / Q000201:enzymology*; D005982:Glutathione Transferase / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D015415:Biomarkers; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D019363:Cytochrome P-450 CYP1A1; D005982:Glutathione Transferase