Svb-dependent enhancers use various combinations of cis -regulatory elements. (a) Linker-scanning mutagenesis of Emin identifies other 10 bp regions required for full transcriptional activity, as deduced from altered patterns of lac-Z immuno-staining (green). Positions of SvbF7, blue and yellow motifs are indicated at the top. (b) Black, red, blue and yellow boxes schematize the distribution, number and orientation of OvoQ6, svbF7, blue and yellow motifs, respectively. Filled boxes represent motifs conserved across Drosophila species, open boxes those detected only in D. melanogaster. (c) Point mutations that disrupt the blue motif in Emin, snE1 and sha3 reduce the activity of all three enhancers, to 40 ± 14% (P < 0.03), 44 ± 6% (P < 0.001), 8 ± 4% (P < 0.001) of wild-type (wt) levels, respectively. (d) Point mutations that disrupt the yellow motif in Emin, 17058 and nyo1 reduce the activity of all three enhancers, to 20 ± 7% (P < 0.03), 16 ± 8% (P < 0.03), 6 ± 3% (P < 0.03) of wild-type levels, respectively.