title: Formation of the A/B cis ring junction of ecdysteroids in the locust, Schistocerca gregaria.
abstract: 1. The mechanism of formation of the A/B cis ring junction of ecdysteroids in the locust Schistocerca gregaria, was investigated by incorporation of [4-14C,3 alpha-3H], [4-14C,4 alpha-3H] and [4-14C,4 beta-3H]cholesterol into 20-hydroxyecdysone in fifth-instar larvae and into ecdysteroid conjugates in ovaries of maturing adult females. 2. In both systems there was retention of the 4 alpha-3H atom in the ecdysteroid and elimination of the 3 alpha- and 4 beta-3H atoms. 3. The 3H retained in the ecdysone formed from [4 alpha-3H]cholesterol in the ovarian system was probably located at C-4. The results are interpreted by postulating the involvement of a 3-oxo-delta 4 intermediate in ecdysteroid biosynthesis in insects.
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004440:Ecdysone / Q000378:metabolism; D026461:Ecdysteroids; D005260:Female; D006110:Grasshoppers / Q000378:metabolism*; D007447:Invertebrate Hormones / Q000096:biosynthesis*; D007814:Larva / Q000378:metabolism; D010053:Ovary / Q000378:metabolism
chemical_list: D026461:Ecdysteroids; D007447:Invertebrate Hormones; D004440:Ecdysone; D002784:Cholesterol