Induction of glutathione S-aryl transferase by phenobarbital in the house fly

Induction of glutathione S-aryl transferase by phenobarbital was studied with three stains of house flies which differed in basal levels of the enzyme. The enzyme was shown to be inducible in two of the three strains tested and the amount of induction was inversely proportional to the basal level of enzyme activity. In dose-dependency tests, a high dose of phenobarbital, 10,000 ppm, was needed to cause significant levels of induction. In a time study, 48 hr was found to be the time at which the highest levels of induction occur. Similarities of this system to house fly microsomal oxidases are discussed.