Fig. 5. Reporter assay for TDF-dependent transcriptional activation. (A) Schematic illustration of the lacZ reporter constructs driven by either the functional (TDS) or the mutant (TDMS) TDF-binding elements. (B-E) Staining of stage 16 embryos with an anti-ß-galactosidase antibody. (B,C) The reporter gene TDS-lacZ was expressed in the tracheae (Tr), head (Hd), heart precursor cells (Ht) and CNS of a tdf⁺ line. (D) The mutant reporter TDMS-lacZ was silent in the tdf⁺ line. (E) TDS-lacZ was not expressed in the tdf^P2 mutant. (F-I) Activation of TDS-lacZ upon ectopic expression of TDF in the posterior salivary gland of a third instar larva. Salivary glands from control TDS-lacZ (F, G) or sgP[Gal4]/+; UAS-tdf, TDS-lacZ/+ (H,I) larvae were stained with anti-TDF (F,H) or anti-ß-galactosidase (G,I) antibodies.