THE BIOTRANSFORMATION OF TRITIATED 3-DEHYDROECDYSONE BY CRAYFISH, PROCAMBARUS-CLARKII

The injection of 3-dehydroecdysone (3dhE, 5 mu g/g), the major ecdyste roid secreted by the Y-organ of crayfish Procambarus clarkii, resulted in apolysis within about 5 days. The hormonal response at the molecul ar level was investigated by injection of the radio-labeled compound; within 3 h of injection of [H-3]3dhE, most radio-isotope was found in the extracted epidermal tissues and identified as ecdysone, 20-hydroxy ecdysone (20E), and their 3 alpha-hydroxy epimers. The biotransformati on was undoubtedly performed in the peripheral area of the Y-organ. Cl eavage of the polar conjugates, using an enzyme from Helix pomatia, ga ve all of the above ecdysteroids including 3dhE. It was also found tha t the biosynthetic site of 3dhE was different from that of ecdysone at the subcellular level of the Y-organ.