Development of microsomal cytochrome P-450 monooxygenases during the last larval instar of the locust, Locusta migratoria: correlation with the hemolymph 20-hydroxyecdysone titer.
Several enzyme activities were measured in microsomes from Malpighian tubules and from fat body of the locust, Locusta migratoria, during the last larval instar and the 20-hydroxyecdysone titer was determined in the hemolymph. Ecdysone 20-monooxygenase, the cytochrome P-450 dependent monooxygenase which converts ecdysone to the active molting hormone 20-hydroxyecdysone had a low activity in the beginning of the instar, but showed a peak in both Malpighian tubules and fat body which coincided with the peak of 20-hydroxyecdysone in the hemolymph. The varying ratios of ecdysone and 20-hydroxyecdysone in L. migratoria hemolymph may therefore be accounted for by these changes in ecdysone 20-monooxygenase activity. The amounts of cytochrome P-450 and the activity of NADPH-cytochrome c reductase also showed a peak on day 5 of the instar, as did the activity of cytochrome P-450 linked lauric acid omega-hydroxylase in fat body microsomes. In larvae experimentally deprived of molting hormone, the activities of the cytochrome P-450 monooxygenases were low. The possible role of ecdysteroids in the control of developmental changes of cytochrome P-450 monooxygenases is discussed.
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004440:Ecdysone / Q000378:metabolism; D004441:Ecdysterone / Q000097:blood*; D005216:Fat Body / Q000201:enzymology; D006110:Grasshoppers / Q000201:enzymology*; D006458:Hemolymph / Q000378:metabolism; D007814:Larva / Q000201:enzymology / Q000254:growth & development; D008317:Malpighian Tubules / Q000201:enzymology; D008861:Microsomes / Q000201:enzymology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism*
D004440:Ecdysone; D004441:Ecdysterone; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C020095:ecdysone 20-hydroxylase; D009251:NADPH-Ferrihemoprotein Reductase