C. Rausell et al., Phenobarbital induction of UDP-glucosyltransferase activity in Drosophila melanogaster Meigen, J ENTOM SCI, 35(4), 2000, pp. 465-473
The inducibility of UDP-glucosyltransferase activities towards the exogenou
s substrates 1-naphthol and 2-naphthol and the endogenous metabolite xanthu
renic acid was demonstrated in Drosophila melanogaster Meigen larvae and ad
ults using phenobarbital as an inducer. In adults, a 3.5-fold increase of g
lucosyltransferase activity toward xanthurenic acid and a 2.0-fold increase
of the activity toward exogenous substrates (1-naphthol and 2-naphthol) wa
s found. In larvae, maximum induction of ail three UDP-glucosyltransferase
activities (2.5-fold and 1.5-fold increase of the activity toward the exoge
nous and endogenous substrates, respectively) was achieved when insects, re
ared on solid medium, were exposed to phenobarbital for 24 h. However, a 24
-h exposure to inducer on liquid medium yielded the same level of induction
as in solid medium only for xanthurenic acid:UDP-glucosyltransferase activ
ity. Repression of the activities toward exogenous substrates also was noti
ced. On this medium, comparable induction to that detected on solid medium
was found when inducer exposure was reduced to 2.5 h. According to the obse
rved Variation resulting from the different conditions of phenobarbital tre
atment, a differential induction of UDP-glucosyltransferase isoenzymes also
was demonstrated. After 2.5 h of inducer exposure, three isoenzymes (every
one specific for each of the three analysed substrates) were detected; whe
reas, after 24 h of inducer treatment, only one isoenzyme, specific for xan
thurenic acid, was detected.