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Cytochrome P4501A induction in rainbow trout gills and liver following exposure to waterborne indigo, benzo(a)pyrene and 3,3',4,4',5-pentachlorobiphenyl
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
2006 (English)In: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 79, no 3, 226-232 p.Article in journal (Refereed) Published
Abstract [en]

We have developed a gill-filament based ethoxyresorufin O-deethylase (EROD) assay to be used as a tool to monitor cytochrome P4501A (CYP1A) induction in caged fish. The present study aimed to compare temporal patterns of EROD induction in gills and liver of rainbow trout (Oncorhynchus mykiss) exposed in the laboratory to readily metabolized and persistent CYP1A inducers, i.e. indigo, benzo[a]pyrene (BaP), and 3,3',4,4',5-pentachlorobiphenyl (PCB#126). Branchial and hepatic EROD activities were examined in fish exposed for 6, 12, or 24h and in fish exposed for 24h and then held in clean water for 2 or 14 days. Furthermore, branchial CYP1A protein expression was localized by immunohistochemistry. All compounds strongly induced branchial EROD activity within 6 h. The highest EROD inductions observed for indigo, BaP, and PCB#126 were roughly similar in gills (52-, 76-, and 74-fold), but differed considerably in liver (11-, 78-, and 200-fold). In indigo- and BaP-exposed fish, both hepatic and branchial EROD activities decreased rapidly in clean water. In PCB#126-exposed fish, decreased branchial and increased hepatic EROD activities were observed following transfer to clean water. The substances gave rise to immunostaining for CYP1A at different cellular sites. All inducers increased the CYP1A-immunostaining in the gill filament secondary lamellae, but PCB#126 also induced a pronounced CYP1A immunoreactivity in cells near the basal membrane of the epithelium of the primary lamellae. The observation that the low BaP and indigo concentrations induced EROD activity markedly in the gills but only slightly or not at all in the liver, supports the contention that readily metabolized AhR agonists may escape detection when hepatic EROD activity is used for environmental monitoring. The results show that gill filament EROD activity is a sensitive biomarker both for persistent and readily metabolized AhR agonists in polluted water.

Place, publisher, year, edition, pages
2006. Vol. 79, no 3, 226-232 p.
Keyword [en]
benzo[a]pyrene, CYP1A, gill, indigo, liver, 3, 3 ', 4, 4 ', 5-pentachlorobiphenyl (PCB#126)
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:uu:diva-95921DOI: 10.1016/j.aquatox.2006.06.006ISI: 000240567200003PubMedID: 16872689OAI: oai:DiVA.org:uu-95921DiVA: diva2:170301
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2011-06-16Bibliographically 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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 311
Keyword
Biology, biomarker, fish, gill, CYP1A, EROD, environmental monitoring, induction, inhibition, PAH, PCB, produced water, Biologi
Identifiers
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)
Opponent
Supervisors
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2009-04-02Bibliographically approved

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Abrahamson, AlexandraBrunström, BjörnBrandt, Ingvar

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