Biochemical Characters And Purification Of Yolk Protein Of Bradysia Odoriphaga And The Hormonal Regulation Of Its Vitellogenesis

The paper dealt with the biochemical characters and purification of vitellin of Bradysia odoriphaga and the hormonal regulation of its vitellogensis to elucidate the machnisms for regulating vitellogensis of Bradysia odoriphaga and research the evolutional relationship between vitellins of Bradysia odoriphaga and other dipteran insects. The results are as follows:The yolk proteins from egg, ovary, hemolymph and fat body of Bradysia odoriphaga were identified by using PAGE and SDS-PAGE. The molecular weights of vitellogenin and vitellin are 138.85 kDa and 148.38 kDa, respectively. Both vitellin and vitellogenin consist of three subunits with the identical molecular weight, 75.47kDa, 41.49kDa and 39.54kDa, respectively.Vitellin sample from eggs of Bradysia odoriphaga was first concentrated by using the ammonium sulfate precipitation, and the concentrated vitellin was further purified by gel filtration chromatography followed by the anion chromatography. Two protein bands from the purified samples were finally identified with PAGE, the smaller protein was the vitellin, accompanied by a bigger protein with its molecular weight of 440 kDa difficulty to be separated from the vitellin. The 440kDa protein is three times of Vn in size, speculating these two proteins have some particular relationship, perhaps a trimer of the Vn.The dynamics of the vitellogenin/vitellin in fat body and ovary at different developmental stages pupae were assayed with indirect ELISA, when the white pupae were treated with different treatments of pyriproxyfen (juvenile hormone analog), precocene II and plant-derived molting homone. And the effects of the three kinds of exogenous hormones on Vg synthesis in fat bodies and Vg accumulation in ovaries were analyzed. Pyriproxyfen at the rate of 0.8μg/μl could activate the synthesis of Vg and promote the ovary to uptake Vg. Precocene II inhibited the systhesis of Vg in fat body by chemical allatectomy and the uptake yolk protein by ovary. The plant-derived molting homone also does activate the synthesis of Vg to some extents. On the basis of dynamics of the vitellin in fat body and ovary at different developmental stages pupae assayed with indirect ELISA in the paper and the soluble protein dynamics determined in the fat body of pupae early, JHIII and 20-E titers at different developmental stages of female pupae were assayed by HPLC. The results indicated that JHШtiters in Bradysia odoriphaga female pupae coincided with the soluble proteins in the body fat and that JH regulated fat body to synthesize Vg. 20-E keeped the similar level from white pupa to grey pupa, peaking at black pupa and showed no relation to the vitellogensis of Bradysia odoriphaga.