Regulation of steroidogenesis in crayfish molting glands: involvement of protein synthesis

Abstract

The involvement of continuous protein synthesis in the mechanisms of crustacean steroidogenesis was investigated using crayfish molting glands (Y-organs). During intermolt, Y-organ steroidogenic activity is low. Eyestalk ablation initiates premolt which is characterized by a rapid increase in the production of ecdysteroids. In vitro incorporation of [ 14C]leucine into TCA-precipitable proteins was measured in Y-organs. A significant increase of de novo protein synthesis was observed in the premolt stage compared to the intermolt stage. On the other hand, cycloheximide totally suppressed protein synthesis within 2 h and simultaneously led to a strong inhibition of the ecdysteroid synthesis. Sinus gland extracts (containing molt inhibiting hormone) also induced both a limited but reproducible inhibition of Y-organ protein synthesis and a pronounced inhibition of ecdysteroid production within 2 h. The results suggest a functional link between protein synthesis in the Y-organ and sustained ecdysteroid production. The analysis of autoradiographs from one-dimensional gel electrophoreses revealed an overall increase in de novo synthesis of glandular proteins in early premolt but also a more specific effect on distinct proteins (increase of 150, 140, 50–60, 22 and 15–18 kDa proteins) which may be more directly involved in the regulation of ecdysteroidogenesis.