Hormonal control of vitellogenin synthesis in Oncopeltus fasciatus

Previous work indicated the existence of two vitellogenins (A and B) in the haemolymph of Oncopeltus fasciatus, and that vitellogenin B was juvenile hormone (JH)-dependent whereas A was not (Kelly and Telfer, 1977). We have extended these results using several electrophoretic techniques in combination with limited proteolysis of key proteins to show that (1) vitellogenin B is present in eggs in a modified form while vitellogenin A cannot be detected in eggs. (2) Vitellogenin A may be a precursor of B since it has a molecular weight of 200,000D, approximately three times that of vitellogenin B (68,000D) and analysis by limited proteolysis shows that two proteins to be nearly identical. (3) Neither ovariectomy nor treatment with the anti-allatotropin, precocene II prohibits the appearance of vitellogenins A and B in the haemolymph. (4) Injection of ecdysone or 20-hydroxyecdysone into adult, male Oncopeltus fasciatus induces the appearance of both vitellogenin A and B in the haemolymph, suggesting the possible involvement of ecdysteroids in the control of vitellogenin synthesis in this species. (5) We have no evidence for JH control of the synthesis of vitellogenin, however, the ratio of vitellogenin A to B in the haemolymph is higher in the precocene-treated females.