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Inhibition of CYP1A activity in fish detected by the gill filament EROD assay - studies on ketoconazole, bitertanol, acacetin and omeprazole
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
(English)Manuscript (Other (popular science, discussion, etc.))
URN: urn:nbn:se:uu:diva-95924OAI: oai:DiVA.org:uu-95924DiVA: diva2:170304
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2010-01-14Bibliographically approved
In thesis
1. Gill EROD Activity in Fish: A Biomarker for Waterborne Ah-receptor Agonists
Open this publication in new window or tab >>Gill EROD Activity in Fish: A Biomarker for Waterborne Ah-receptor Agonists
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Induction of the cytochrome P450(CYP)1A protein and the connected increase in 7-ethoxyresorufin O-deethylase (EROD) activity are common biomarkers in fish. Enhanced activity of this protein signals exposure to Ah-receptor agonists such as chlorinated dioxins, co-planar polychlorinated biphenyls (PCBs) and certain polycyclic aromatic hydrocarbons (PAHs). The EROD biomarker is commonly analyzed in liver microsomes. However, the gill is directly exposed to waterborne pollutants, and in this thesis the gill filament EROD assay was therefore evaluated as a monitoring tool for waterborne CYP1A inducers in fish. Originally developed in rainbow trout (Oncorhynchus mykiss), the assay was here applied in various limnic and marine species. Following exposure to low waterborne concentrations of the readily metabolized CYP1A inducers benzo(a)pyrene (BaP) and indigo, a strong EROD induction was observed in the gill but not in the liver. This likely reflected metabolic clearance of the inducers in gill and other extrahepatic tissues. The high sensitivity of the gill was confirmed in studies of fish caged in waters in urban and rural areas in Sweden where the gill consistently showed a more pronounced EROD induction compared with the liver and the kidney. Fish caged in the reference waters showed surprisingly strong gill EROD induction and CYP1A immunostaining. Consequently, there may be CYP1A inducers present in the aquatic environment that are not yet identified. The assay was further applied in Atlantic cod (Gadus morhua) as a biomarker of exposure to crude oil and produced water (PW) from oil fields in the North Sea. The assay was finally adapted to detect inhibiting compounds, and an imidazole, a triazole and a plant flavonoid turned out to be potent gill EROD inhibitors. The overall conclusion from the studies of this thesis is that the gill filament EROD assay is a practical and sensitive biomarker of exposure to waterborne CYP1A inducers in various fish species. The induction of gill EROD activity in fish also at the reference sites in the field studies calls for further studies on background contamination in Swedish waters.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 52 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 311
Biology, biomarker, fish, gill, CYP1A, EROD, environmental monitoring, induction, inhibition, PAH, PCB, produced water, Biologi
urn:nbn:se:uu:diva-7899 (URN)978-91-554-6902-3 (ISBN)
Public defence
2007-06-02, Lindahlsalen, Evolutionsbiologiskt centrum (EBC), Norbyvägen 18 A, Uppsala, 10:00 (English)
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2009-04-02Bibliographically approved

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