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Title: Induction of cytochrome P450-associated monooxygenases in northern leopard frogs, Rana pipiens, by 3,3{prime},4,4{prime},5-pentachlorobiphenyl

In the past decade, biochemical and physiological characteristics such as hepatic detoxifying system. DNA adducts, thyroid malfunction, and acetylcholinesterase inhibition have been used extensively as biomarkers for contaminant exposure. Northern leopard frogs (Rana pipiens) were injected intraperitoneally either with a solution of polychlorinated biphenyl (PCB) 126 m corn oil at a concentration of 0.2, 0.7, 2.3, or 7.8 mg/kg body weight or with corn oil alone. Appropriate assay conditions with hepatic microsomes were determined for four cytochrome P450-associated monooxygenases: ethoxyresorufin-O-dealkylase (EROD), methoxy-ROD (MROD), benzyloxy-ROD (BROD), and pentoxy-ROD (PROD). One week after PCB administration, the specific activities of EROD, MROD, BROD, and PROD were not elevated at doses {le}0.7 mg/kg (p > 0.05) but were significantly increased at doses {ge}2.3 mg/kg compared to the control groups (p < 0.05). The increased activities of these four enzymes were 3 to 6.4 times those in the control groups. The increased activities were maintained for at least 4 weeks. Because of a lack of induction at low doses of PCB 126, which were still relatively high compared to currently known environmental concentration, the authors suspect that EROD, MROD, BROD, and PROD activities are not sensitive biomarkers for coplanar PCB exposure in leopard frogs.
Authors:
; ;  [1] ;  [2]
  1. Univ. of Wisconsin, Madison, WI (United States)
  2. Geological Survey, Laurel, MD (United States). Patuxent Wildlife Research Center
Publication Date:
OSTI Identifier:
675401
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Toxicology and Chemistry; Journal Volume: 17; Journal Issue: 8; Other Information: PBD: Aug 1998
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 56 BIOLOGY AND MEDICINE, APPLIED STUDIES; WATER POLLUTION; BIOLOGICAL INDICATORS; BIOLOGICAL MARKERS; OXYGENASES; ENZYME INDUCTION; FROGS; POLYCHLORINATED BIPHENYLS