Fig. 2. The ftz-AE1 interaction overcomes the suHw insulator. Transgenic Drosophila embryos containing the AE1 enhancer between divergently transcribed promoter-reporter fusion genes were hybridized with antisense probes for reporter genes. The transgene is diagrammed below each pair of embryos with the reporter gene directly below the embryo showing the corresponding expression. Orientation and location of the promoters in the diagrams are indicated by arrows. The size and distance of the DNA elements are not to scale. Germband extension stage embryos are shown anterior to the left and dorsal up. (A,B) AE1 specifically activates ftz/CAT expression (A, CAT expression) but not the Scr/lacZ expression (B, lacZ expression). (C,D) AE1-ftz/CAT interaction overcomes the intervening the suHw insulator (C, CAT expression) and no AE1 specific expression is detected from the Scr/lacZ fusion gene (D, lacZ expression). The inset in each panel shows the endogenous Scr expression at or near the same stage as an internal control of the in situ staining (see Results, and Materials and Methods for details).
