Vitellin synthesis in relation to oogenesis in in vitro‐incubated ovaries of <i>Penaeus semisulcatus</i> (crustacea, decapoda, penaeidae)

Abstract

Abstract Ovaries of the penaeid shrimp Penaeus semisulcatus in various stages of oocyte development were incubated in vitro with 14 C or 3 H leucine. Protein synthesis was measured by TCA precipitation and vitellin specific synthesis by radioimmunoprecipitation. The proteins synthesized were subjected to native or SDS denaturative gel electrophoresis and visualized by fluorography. The results led to the following conclusions: 1) Protein synthesis was found to depend on the concentration of leucine in the culture media. 2) A relatively constant level of vitellin synthesis was observed in ovaries with oocytes ranging in size between 100 and 380 μm. 3) The vitellogenic stage was found to occur in ovaries with oocytes ranging between 100 and 300 μm in size. During this period, 40–60% of the in vitro–synthesized proteins were found to be immunologically identical to vitellin. 4) A decrease in the relative amount of vitellin synthesized was found with the appearance of cortical crypts in oocytes exceeding 300 μm in diameter. 5) The protein immunologically identical to vitellin, which was synthesized in vitro by the ovaries, was found to consist of the subunits found in purified native vitellin. 6) A bioassay system for testing the effect of various factors on vitellin synthesis is suggested by in vitro incubations of several pieces removed from the ovaries of one female.