Fig. 2. (A) Map of the Fab-7 boundary and the various HS1 subfragments used in the transgene assays. The virilis homology region is indicated by V. (B) Map of the ftz:hsp70-lacZ reporter construct. Inserts placed upstream of the ftz UPS enhancer are in the non-blocking position (NB), while inserts placed between the NE enhancer and the hsp70 promoter are in the blocking position. (C,D) lacZ expression in embryos from representative lines homozygous for ftz:hsp70-lacZ transgenes carrying different boundary elements. (C) Random DNA, five binding sites for Su(Hw) and 1.2kb Fab-7. (D) Tetramerized pHS1 fragments: pHS1x4 in the blocking position, pHS1x4 in the non-blocking position (NB), pHS1Ax4 and pHS1Bx4. All embryos in Fig. 2 (and also in Fig. 4) were stained in parallel as described elsewhere (Hagstrom et al., 1996) for a direct comparison of staining intensities.