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  • Title: Development of microsomal cytochrome P-450 monooxygenases during the last larval instar of the locust, Locusta migratoria: correlation with the hemolymph 20-hydroxyecdysone titer.
    Author: Feyereisen R, Durst F.
    Journal: Mol Cell Endocrinol; 1980 Nov; 20(2):157-69. PubMed ID: 6777215.
    Abstract:
    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.
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