Variations du taux des ecdystéroïdes au cours des cycles de mue et de vitellogenèse chez le Crustacé Amphiphode,Orchestia gammarellus

Abstract

Ecdysteroid titer in whole extracts of female O. gammarellus varies during the course of the moult cycle: it is minimal at the beginning of the intermoult cycle (stages A, B and C_a) and in D₀, and maximal in D₂. In hemolymph, the hormone content presents a single peak level in D₂; this peak is constituted by ecdysterone, as revealed by HPLC. Ovaries, at the end of vitellogenesis, contain ecdysterone and low polarity substances. Ecdysteroids are also present in eggs after laying. Variations in ecdysteroid levels seem to influence oocyte growth; vitellogenin synthesis, however, is independent of hormonal fluctuations.