Meeting Abstract
Vitellogenin is a protein synthesized and secreted from the hepatopancreas of crustaceans during ovarian maturation. Vg is taken up by ovaries and is modified to vitellin (Vn) during maturation; it is the yolk-protein that will nourish the developing embryos. We are purifying Vg from the Northern spot prawn (Pandalus platyceros) as a first step to developing a homologous ELISA with which to study the reproductive physiology of this species. P. platyceros is a commercially important protandric shrimp species and as such transforms from a small functional male to a much larger functional female. Our objective is to develop a non-lethal method with which to study physiological changes associated with this sexual differentiation. We are interested in the onset of vitellogenesis in the transitional stage. P. Pandalus ovaries were homogenized and proteins separated using 25%, 40%, 50% and 60% ammonium sulfate precipitation. The 50% ammonium sulfate fraction was enriched in a protein we suspect is Vg or Vn. After dialysis to remove excessive salts, proteins were separated using 10% SDS-PAGE. Western blot analysis using a heterologous antibody showed two major proteins that could be subunits of a larger protein with approximate molecular masses of 92 and 105 kD. Native gel electrophoresis using 8% PAGE revealed a large protein with an approximate molecular mass of 230 kD. Polyclonal antibodies will be generated against this protein and used to develop a homologous ELISA.
