POSSIBLE ROLES OF 20-HYDROXYECDYSONE IN THE CONTROL OF OVARY MATURATION IN THE WHITE SHRIMP PENAEUS-VANNAMEI (CRUSTACEA, DECAPODA)

20-HE is the predominant ovarian ecdysteroid at the early stage of ovary maturation whereas ecdysone and an apolar ecdysteroid are abundant at the late ovarian cycle, Injection of 20-HE into intermolt adult females does not stimulate ovarian growth but promotes rapid molting, Ovarian polypeptides in the ranges of 210-250 kDA, 120-158 LDA, 97 kDa and 72 kDa are accumulated (or synthesized) during secondary vitellogenesis when the ovary ecdysteroid level is increasing, These substances may be important for maturation of the oocytes. There is no significant effect of 20-HE on total protein synthesis in ovaries of stage I, but 20-HE inhibits total protein synthesis in stage III ovaries in a dose dependent manner, 20-HE stimulates the synthesis of some polypeptides but inhibits the synthesis of others at the early and mid stages of ovary development, This result suggests that 20-HE regulates ovary protein synthesis by controlling the differential expression of ecdysteroid responsive genes.