Effect of estradiol on vitellogenesis and oocyte development of female swimming crab, Portunus trituberculatus

The vitellogenesis process of crustacean includes endogenous vitellogenic stage and exogenous vitellogeneic stage because the major vitellogenesis sites of two stages are localized in ovary and hepatopancreas, respectively. The present study was conducted to investigate the effects of different concentrations (0, 10(-10), 10(-9), 10(-8), 10(-7) and 10(-6) mol/L) of exogenous estradiol (E-2) on Vitellogenin (Vg)-mRNA expressions and Vg/Vitellin (Vn) levels in the ovaries and hepatopancreas for both endogenous and exogenous vitellogenic stage via in vitro experiment, and the oocyte diameters were further measured for the female swimming crab (Portunus trituberculatus). During endogenous vitellogenic stage, the Vg-mRNA expression level, Vn contents and the oocyte diameters of endogenous vitellogenic ovaries were significantly promoted in low concentration of E-2 treatment (10(-9) mol/L and 10(-8) mol/L). However, the Vg-mRNA level in hepatopancreas was not enhanced by increasing concentrations of exogenous E-2 and the hepatopancreatic Vg/Vn level was not detectable in this stage. During exogenous vitellogenic stage, only high-concentration of E-2 treatment (10(-6) mol/L) could significantly improve the Vg-mRNA expression levels in ovary, while exogenous E-2 had no significant effect on Vn contents and oocyte diameters. Moreover, the higher Vg-mRNA expression and Vg/Vn level in the hepatopancreas were detected in the high-concentration E-2 treatment (10(-7) mol/L-10(-6) mol/L). In conclusion, all results together indicated that exogenous E-2 had a significant effect on vitellogenesis in ovaries at endogenous vitellogenic stage and in hepatopancreas at exogenous vitellogenic stage, but the effects of E-2 were dose dependent and stage-specific.