Ecdysone 20-monooxygenase activity during larval-pupal-adult development of the tobacco hornworm, Manduca sexta.

摘要

Using an in vitro radioassay, the levels of ecdysone 20-monooxygenase activity were quantified during embryogenesis in the egg, and in the fat body and midgut tissues during the 4th and 5th larval instars and pupal-pharate adult stage of Manduca sexta. Although basal, ecdysone 20-monooxygenase activity was detected during the latter stages of larval embryogenesis. Post-embryologically, a single major peak was detected in both fat body and midgut tissues during each stadium. In the 4th larval instar, both fat body and midgut ecdysone 20-monooxygenase activities were found to peak at the time of spiracle apolysis; both activities dropped to basal levels by the time of ecdysis. During the 5th larval stadium, fat body steroid hydroxylase activity wasfound to rise during the feeding stage (days 1-4), then dropped back to basal levels by the onset of pharate pupal development on day 7 of the stadium. Midgut monooxygenase activity during the 5th larval instar, however, remained basal during the feedingstage, rose dramatically to peak on day 5 with the onset of wandering, then dropped back to basal levels by the onset of pharate pupal development. Both fat body and midgut hydroxylase activities were basal during the pupal stage and only rose late in pharate-adult development, just prior to adult eclosion.