Titration by RIA of ecdysteroids during embryogenesis of Drosophila shows one single peak at 8 h, i.e. the time of germ-band shortening. An analysis of the ecdysteroids reveals a general shift from low polarity material at 6 h to free ecdysone and (less) 20-hydroxyecdysone at 8 h, and finally to ecdysteroids of mostly higher polarity at 12 h. Adult body walls, when incubated with tritiated 20-hydroxyecdysone, can produce the 22-acetate of this ecdysteroid which then has similar chromatographic properties as ecdysone. We have isolated the putative ecdysone fraction from 8 h embryonic extracts and showed by enzymatic hydrolysis and HPLC that the embryo does not contain 20-hydroxyecdysone-22-acetate, but rather free ecdysone.
ASJC Scopus subject areas
- Insect Science