Biosynthesis and regulation of juvenile hormone III, juvenile hormone III bisepoxide, and methyl farnesoate during the reproductive cycle of the grey fleshfly, Neobellieria (Sarcophaga) bullata
1998
Bylemans, D. | Borovsky, D. | Ujvary, I. | DeLoof, A.
To study the effect of brain signals on the biosynthesis of juvenile hormone by the corpora allata of the grey fleshfly Neobellieria bullata, exposed corpora allata connected to the brain were surgically removed from sugar-fed flies and incubated in vitro with L-[3H-methyl]methionine. After incubation, the media together with the tissues were analyzed by HPLC. [3H]Juvenile hormone III (JH III), [3H]JH III bisepoxide (BE), [3H]methyl farnesoate (MF) and an unknown [3H]labeled metabolite (Un) were identified as the primary products. The rate of synthesis of [3H]JH III bisepoxide was higher than that of [3H]JH III, [3H]MF and [3H]Un. Two days after a liver meal, female flies synthesized more JH III, MF, BE, and the Un than did males. Synthesis of JH III, BE, and MF in females was lower during the previtellogenic, sugar-feeding period than during the vitellogenic liver-feeding period. Isolated corpus cardiacumcorpus allatum (CC-CA) complexes that were incubated in vitro synthesized less JH III, MF, and BE, as compared to complexes that were attached to the brain, indicating that the brain probably modulates the biosynthesis of JH III, MF, and BE in the corpora allata. Upon incubation of brain-CC-CA complexes with Neb-TMOF (10(-8) M), Neb-colloostatin (10(-8) M), ovarian, or brain extracts resulted in significant inhibition of JH III and BE biosynthesis in the presence of ovarian extracts. These results indicate that allatostatin-like factors are present in the ovary of the flesh fly.
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