Rattner, B. A., Melancon, M. J., Custer, T. W., Hothem, R. L., King, K. A.,
LeCaptain, L. J., Spann, J. W., Woodin, B. R., and Stegeman, J. J., 1993,
Biomonitoring environmental contamination with pipping black-crowned night heron
embryos: Induction of cytochrome P450: Environmental Toxicology and Chemistry, v.
12, no. 9, p. 1719-1732.

Abstract

Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins
were measured in pipping black-crowned night heron (Nycticorax nycticorax) embryos
collected from a reference site (next to the 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). In a laboratory
study, artificially incubated night heron embryos from the reference site were treated
with 3-methylcholanthrene (200 mu g administered into the air cell 2 d before pipping)
or phenobarbital (2 mg daily for 2 d before pipping). Compared to controls (untreated
+ vehicle-treated embryos), 3-methylcholanthrene induced a greater than fivefold
increase in activities of several monooxygenases (arylhydrocarbon hydroxylase, AHH;
benzyloxyresorufin-O-dealkylase, BROD; ethoxyresorufin-O-dealkylase, EROD;
pentoxyresorufin-O-dealkylase, PROD) and a greater than 100-fold increase in the
concentration of immunodetected cytochrome P450 1A (CYP1A). Phenobarbital
treatment resulted in only a slight increase in BROD activity but induced proteins
recognized by antibodies to cytochrome P450 2B (CYP2B) by 2,000-fold. In a field
study, activities of AHH, BROD, EROD, and ethoxycoumarin-O-dealkylase (ECOD)
were up to 85-fold higher in pipping black-crowned night herons collected from Cat
Island compared to other sites. Hepatic CYP1A and CYP2B cross-reactive proteins
were detected in significantly more individuals from Cat Island than from the reference
site. Greatest burdens of total PCBs and p,p'-DDE were detected in embryos from Cat
Island. Cytochrome P450-associated monooxygenase activities and cytochrome P450
proteins (AHH, BROD, EROD, ECOD, CYP1A, CYP2B) were significantly
associated with total PCB burdens (r = 0.50-0.72). These data indicate that cytochrome
P450 may be a useful biomarker of exposure to some PCB mixtures in black-crowned
night heron embryos.

Keywords

cytochrome-P450, biomarkers, environmental-monitoring, Nycticorax-nycticorax,
toxicity-testing, unspecific-monooxygenase, USA, pollution-monitoring, bioindicators,
cytochromes, bird-eggs, embryos, indicator-species, pollution-indicators,
pollution-monitoring