OVARY-SPECIFIC INTERACTION OF ECDYSONE 22-PHOSPHATE WITH PROTEINS IN ADULT DROSOPHILA-MELANOGASTER (DIPTERA, DROSOPHILIDAE)

Radiotracer experiments were performed to analyze the interaction of m etabolites of ecdysone with proteins in adult Drosophila melanogaster females. [H-3]Ecdysone was injected into the abdomen and after 4 h of incubation the flies were dissected. PBS-soluble material of the ovari es, haemolymph, gut and abdominal carcass were separated by gel-filtra tion. In all samples, two peaks containing radioactivity eluted with m acromolecules (probably proteins) of an apparent molecular mass of mor e than 1,000 kDa (peak I) and about 500 kDa (peak II). In the extracts of the ovaries an additional peak in the molecular weight range of ab out 50 kDa (peak III) was detected. In all samples free ecdysone metab olites, which did not interact with macromolecules were detected. The radioactivity in the ovary-specific peak III was mainly due to ecdyson e 22-phosphate. The high molecular weight peak I contained radioactive 22-fatty acyl esters of ecdysone and the radioactive material of peak II consisted of a highly complex mixture of ecdysteroids.