Characterization of mixed‐function oxidase systems of the nestling herring gull and its implications for bioeffects monitoring

Abstract

AbstractThe hepatic mixed‐function oxidase system was characterized in embryonic and nestling herring gulls (Larus argentatus). The activity of aminopyrine N‐demethylase decreased significantly with the age of the nestlings. No consistent changes in 7‐ethyoxyresorufin O‐deethylase, benzo[a]pyrene 3‐hydroxylase or cytochrome P450 levels with age were found. Levels of organochlorines were determined in individual livers for the 21‐d‐old nestlings. Correlations among organochlorine residue levels were good, and the activities of aminopyrine N‐demethylase and benzo[a]pyrene 3‐hydroxylase correlated with each other and with cytochrome P450 levels. No correlations were found with 7‐ethoxyresorufin O‐deethylase activity, and none of the enzyme levels correlated with the organochlorine residue levels. However, cytochrome P450 levels correlated with both hexachlorobenzene and oxychlordane levels. The implications for the use of the mixed‐function oxidase system for environmental monitoring of exposure to organochlorines and polynuclear aromatic hydrocarbons are discussed.