Induction of an inactivation pathway for ecdysteroids in larvae of the cotton leafworm, Spodoptera littoralis.
Treatment of the last-instar larvae of the cotton leafworm (Spodoptera littoralis) with ecdysteroids (moulting hormones) results in the induction of an ecdysteroid-inactivation pathway. Administration of ecdysone, 20-hydroxyecdysone or an ecdysteroid agonist, RH 5849, leads to induction of an ecdysteroid 26-hydroxylase activity. This induction occurred in both early sixth-instar larvae and in older larvae which had been head-ligated to prevent the normal developmental increase in ecdysone 20-mono-oxygenase activity. The induction of 26-hydroxylase activity requires both RNA and protein synthesis, as demonstrated by experiments involving actinomycin D and cycloheximide. The 26-aldehyde derivative of ecdysone and ecdyson-26-oic acid were also formed from ecdysone in the RH 5849-induced systems. Formation of the aldehyde and the corresponding 26-oic acid (ecdysonoic acid) from 26-hydroxyecdysone was directly demonstrated in a cell-free system, thus establishing the following inactivation pathway: Ecdysteroid-->26-hydroxyecdysteroid-->ecdysteroid 26-aldehyde-->ecdysteroid 26-oic acid.
Department of Biochemistry, University of Liverpool, U.K.
J H
JH
Chen
M
M
Kabbouh
M J
MJ
Fisher
H H
HH
Rees
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D053493:Cholestanetriol 26-Monooxygenase; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004440:Ecdysone / Q000378:metabolism / Q000494:pharmacology; D026461:Ecdysteroids; D004441:Ecdysterone / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D006834:Hydrazines / Q000494:pharmacology; D007447:Invertebrate Hormones / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D008675:Metamorphosis, Biological; D009036:Moths / Q000187:drug effects / Q000378:metabolism*; D013250:Steroid Hydroxylases / Q000096:biosynthesis / Q000378:metabolism; D013256:Steroids / Q000037:antagonists & inhibitors* / Q000378:metabolism
D026461:Ecdysteroids; D006834:Hydrazines; D007447:Invertebrate Hormones; D013256:Steroids; C056565:1,2-dibenzoyl-tert-butylhydrazine; D003609:Dactinomycin; D004440:Ecdysone; D004441:Ecdysterone; D003513:Cycloheximide; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; D053493:Cholestanetriol 26-Monooxygenase; C020095:ecdysone 20-hydroxylase