Correlation of mixed-function oxidase activity with ultrastructural changes in the liver of a marine fish

Specimens of mullet (Mugil cephalus), a marine fish, were given single doses of 3-methylcholanthrene intraperitoneally and the activity of the microsomal mixed-function oxygenase system in the liver was measured by the metabolism of benzo(a)pyrene. The enzyme system was found to be inducible with concomitant ultrastructural changes in the hepatocytes. The specific activity and the metabolic profile approximate those of the rat.