M. J. Melancon T. W. Custer R. L. Hothem Kirk A. King L. J. LeCaptain J. W. Spann Bruce R. Woodin John J. Stegeman Barnett A. Rattner 1993 <p><span>Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins were measured in pipping black-crowned night heron (</span><i>Nycticorax nycticorax</i><span>) 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 μg 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-</span><i>O</i><span>-dealkylase, BROD; ethoxyresorufin-</span><i>O</i><span>-dealkylase, EROD; pentoxyresorufin-</span><i>O</i><span>-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-</span><i>O</i><span>-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&nbsp;</span><i>p,p</i><span>′-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 (</span><i>r</i><span>&nbsp;= 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.</span></p> application/pdf 10.1002/etc.5620120921 en Society of Environmental Toxicology and Chemistry Biomonitoring environmental contamination with pipping black-crowned night heron embryos: Induction of cytochrome P450 article