Figure 5

Fast onset of GAL4 driven expression relative to embryonic developmental time. Transheterozygous eggs were collected for one hour and aged for 18 hours before heat shock. They were then incubated at 25°C/77°F (a-m) or 32°C/90°F (n-y) respectively. At given time points, tGFP expression was detected by in-situ hybridization. (a, b) At 25°C, there is no expression of the reporter gene two hours after heat shock. (c) After 4 h weak expression is detected. (d) After 6 h strong expression of the reporter gene is seen. (n) At 32°C there is no expression directly after heat shock. The onset of expression is seen after 2 h (o) and remains high during the subsequent two hours (p, q). (e-m) and (r-y) show higher magnifications of the respective embryos above. Judged from head morphology and appendage outgrowth, embryonic development has progressed little between heat shock and first appearence of reporter gene expression (compare e, i to g, l and r, v to s, w).