Identification of 20E-regulated genes in Drosophila cultured larval organs

To identify 20E-regulated genes, wandering third instar larvae were dissected and their organs were cultured in the presence of either no hormone, 20E alone, cycloheximide alone, or 20E plus cycloheximide for six hours. Keywords: Hormone response Eight partial blue gut third instar larvae were dissected in each well of a 9 well glass dish (Corning) and cultured in ~100 µl oxygenated Schneiders Drosophila Medium (Gibco) at 25°C. Cultures were incubated in an a styrofoam box under a constant flow of oxygen. Following an initial incubation of 1 hour, the medium was removed and replaced with either fresh Schneiders Drosophila Medium (no hormone), medium plus 8.5x10-5 M cycloheximide (Sigma), medium plus 5x10-6 M 20-hydroxyecdysone (Sigma), or medium plus cycloheximide and 20E, each for 6 hrs at 25°C. Organs were collected and RNA extracted from these samples was analyzed on Affymetrix Drosophila Genome Arrays.