Figure 3
From: Quantitative analysis of Hedgehog gradient formation using an inducible expression system
Schematic diagram of Gal4-Gal80 inducible expression system. (A) Inducing Hh-GFP expression. Vials are kept at 18°C, the Gal80 permissive temperature where tubulin-Gal80 blocks Gal4-mediated transcription. Upon a shift to 32°C, Gal80 repression is relieved and Gal4 transcription proceeds. Hh-GFP is expressed in the posterior cells with Hh-Gal4, and UAS-dsRed marks the expressing cells. (B) Inducing Hh-GFP expression in shits1 mutant background. Vials are kept at 18°C, the Gal80 permissive temperature and shits1 mutant restrictive temperature. Upon a shift to 32°C, Gal4 transcription proceeds while endocytosis is blocked. Wild-type Shi is expressed in the posterior to restore endocytosis in the expressing cells. The resulting Hh-GFP movement into the anterior would be due solely to shi independent mechanisms. Hh-Gal4 is used again to drive transgene expression.