Relation among cytochrome P450, Ah-active PCB congeners and dioxin equivalents in pipping black-crowned night-heron embryos
- National Biological Survey, Laurel, MD (United States). Patuxent Environmental Science Center
- National Biological Survey, Columbia, MO (United States). Midwest Science Center
Pipping black-crowned night-heron (Nycticorax nycticorax) embryos were collected from a relatively uncontaminated site (next to Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). Hepatic cytochrome P450-associated mono-oxygenates and cytochrome P450 proteins, induced up to 85-fold relative to the reference site, were associated with concentrations of total polychlorinated biphenyls (PCBs) and 11 PCB congeners that are presumed to express toxicity through the arylhydrocarbon (Ah) receptor. Multiple regression revealed that up to 86% of the variation of cytochrome P450 measurements was accounted for by variation in the concentration of these PCB congeners. Toxic equivalents (TEQs) of sample extracts, predicted mathematically (summed product of PCB congener concentrations and toxic equivalency factors), and dioxin equivalents (TCDD-EQs), derived by bioassay (ethoxyresorufin-O-dealkylase activity of treated H4IIE rat hepatoma cells), were greatest in Cat Island samples. Cytochrome P450-associated monooxygenases and cytochrome P450 proteins were related to TEQs and TCDD-EQs; adjusted r[sup 2] often exceeded 0.5 for the relation among mathematically predicted TEQs and cytochrome P450 measurements. These data extend previous observations in heron embryos of an association between P450 and total PCB burdens to include Ah-active PCB congeners, and presumably other compounds, which interact similarly with the AH receptor. Benzyloxyresorufin O-dealkylase, ethoxyresorufin O-dealkylase, and cytochrome P450 1A appear to be the most reliable measures of exposure to Ah-active PCB congeners in black-crowned night-heron embryos. These findings provide further evidence that cytochrome P450-associated parameters have considerable value as a biomarker for assessing environmental contamination of wetlands.
- OSTI ID:
- 7101702
- Journal Information:
- Environmental Toxicology and Chemistry; (United States), Vol. 13:11; ISSN 0730-7268
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIRDS
SENSITIVITY
DIOXIN
TOXICITY
LAKE MICHIGAN
WATER POLLUTION
OXYGENASES
ENZYME INDUCTION
POLYCHLORINATED BIPHENYLS
SAN FRANCISCO BAY
BIOLOGICAL MARKERS
METABOLISM
ANIMALS
AROMATICS
CHLORINATED AROMATIC HYDROCARBONS
ENZYMES
GENE REGULATION
GREAT LAKES
HALOGENATED AROMATIC HYDROCARBONS
HETEROCYCLIC COMPOUNDS
LAKES
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDOREDUCTASES
PACIFIC OCEAN
POLLUTION
PROTEINS
SEAS
SURFACE WATERS
VERTEBRATES
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)
560300 - Chemicals Metabolism & Toxicology