title: The in vitro synthesis and secretion of alpha-ecdysone by the ring glands of the fly, Sarcophaga bullata.
abstract: The in vitro secretory product of larval Sarcophage bullata ring glands has been identified as 2beta, 3beta, 14alpha, 22R, 25-pentahydroxy-5beta-cholest-7-en-6-one (alpha-ecdysone). Mid to late 3rd instar larval ecdysones were isolated and identified as 2beta, 3beta, 14alpha, 20R, 22R, 25-hexahydroxy-5beta-cholest-7-en-6-one (beta-ecdysone) and alpha-ecdysone at a ratio of 27:1. The low level of alpha-ecdysone in vivo, relative to its exclusive in vitro synthesis and secretion by the ring glands, is a function of the very active C20 hydroxylation mechanism in tissues peripheral to the ring gland. The role of alpha-ecdysone as a prohormone in dipteran metamorphosis is discussed.
mesh_terms: D000818:Animals; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004175:Diptera / Q000378:metabolism*; D004440:Ecdysone / Q000096:biosynthesis*; D007700:Kinetics; D007814:Larva; D008675:Metamorphosis, Biological; D012627:Sebaceous Glands / Q000378:metabolism*
chemical_list: D004440:Ecdysone