Comparative studies on ecdysone metabolism between mature larvae and pharate pupae in the fleshfly, Sarcophaga peregrina

Abstract

AbstractMetabolites of radioactive ecdysone or 20‐hydroxyecdysone in larvae and pharate pupae of Sarcophaga peregrina were separated and identified by using thin‐layer chromatography, high‐performance liquid chromatography, and chemical methods. At the larval stage ecdysone was metabolized to biologically less active ecdysteroids predominantly through 20‐hydroxyecydsone, at the pharate pupal stage, to other ecdysteroids which were tentatively identified as 26‐hydroxyecdysone, 3‐epi‐26‐hydroxyecdysone, and 3‐epi‐20,26‐dihydroxyecdysone. Ecdysteroid acids were found in the polar metabolites during pharate pupal‐pupal transformation, but scarcely detected in the larval metabolites. These acids were presumed to be ecdysonoic acid, 20‐hydroxyecdysonoic acid, and their epimers. The conjugates of ecdysteroid that released the free ecdysteroids by enzymatic hydrolysis were produced more in larvae than in pupae, whereas the very polar ecdysteroids that were not affected by the enzyme were found more in pupae. Therefore, there are different metabolic pathways of ecdysone between these two successive developmental stages, and the alteration of the metabolic pathway may serve as one of the important factors in a regulatory mechanism of molting hormone activity which is responsible for normal development of this insect.