Oosorption in the stink bug, Plautia crossota stali: induction and vitellogenin dynamics

Oosorption, resorption of developing oocytes in the ovary, in P. c. stali is characterized by changes in appearance of oocytes from opaque greyish green or orange to transparent, degeneration of yolk granules and disappearance of oocyte contents. Starvation and virginity were indicated to be factors that induce oosorption. SDS PAGE/Western blotting analysis using anti-vitellogenin antiserum detected two major and many minor bands in haemolymph samples. Egg extracts showed a more complicated set of positive bands in the same analysis. Yolk protein, vitellin, therefore, seemed to be formed after complicated processing of vitellogenin following its uptake by the oocytes. In starved, oosorption-induced females, vitellogenin concentration in the haemolymph was lower than that of fed females, and Western blotting failed to detect either oosorption-specific or ovary-specific peptide fragments in haemolymph samples collected from those females. These results suggest that once oosorption was induced vitellogenin/vitellin in oocytes was degraded rapidly and released into the haemolymph in the form of amino acids or small peptides too small to be recognized by the anti-vitellogenin antiserum.