| Summary: | 碩士 === 國立中興大學 === 昆蟲學系 === 92 === Effects of diet and hormones on the expression of vitellogenins in the oriental fruit fly, Bactrocera dorsalis (Hendel)
Mie-Chun Chang
ABSTRACT
The effects of diet and insect hormones on the expression of vitellogenin (Vg) mRNA and proteins in Bactrocera dorsalis (Hendel) were investigated in this study. Using RT-PCR, we demonstrated that the Bdvg1 (accession no. AF368053) and Bdvg2 (accession no. AF368054) start expression on the first day after eclosion. Treatment of the newly emerged females with 20 g/l precocene II, the Bdvg1 and Bdvg2 were delayed their expression about two to three days. Replenishment of precocene-treated females with juvenile hormone analog (JHA, pyriproxyfen), the Bdvg1 and Bdvg2 expression were recovered; however, replenishment with 20-hydroxyecdysone resulted no increase in the Bdvg1 and Bdvg2 expression. The vitellogenin genes were not detected under dietary protein deficiency, i.e. sugar-fed insects. Replenishment with JHA to the sugar-fed females caused slightly increase on the levels of the Vg mRNAs; however, it could not induce their protein synthesis. Finally, removal of the ovaries (i.e. ovariotomy) of newly emerged females obstructed the expression of the Bdvg1 and Bdvg2; however, the gene expression were rescued when replenished with 20-hydroxecdysone. In conclusion, these data suggest that both dietary protein and hormones are required for the vitellogenin synthesis in female B. dorsalis. Possibly, dietary protein can induce of juvenile hormone release, and then, to stimulate the ovaries to synthesize ecdysteroid; subsequently, ecdysteroids further stimulate the fat body to synthesize vitellogenins.
|
|---|
