Fig. 2. GAL4-EcR and GAL4-USP are widely activated by the late larval ecdysteroid pulse. hs-GAL4-EcR; UAS-nlacZ (GAL4-EcR) or hs-GAL4-USP; UAS-nlacZ (GAL4-USP) third instar larvae were heat treated, allowed to recover for several hours, staged at either 12-18 hours before puparium formation (–18 h; A-D) or approx. 2 hours before puparium formation (–2 h; E-L), and processed for histochemical staining. Blue precipitate indicates expression of nuclear ß-galactosidase. GAL4-EcR (A-D) and GAL4-USP (data not shown) are not activated in third instar larvae 12-18 hours before puparium formation. In contrast, both GAL4-EcR (E-H) and GAL4-USP (I-L) are widely activated in late third instar larvae, as depicted in the midgut, hindgut, muscles and fat body.
