A series of GAL4 drivers was constructed by David Miller based on the analysis of Scr cis-regulatory regions in Gindhart et al. 1995 (http://flybase.org/reports/FBrf0080052.html). The constructs recapitulate the expression patterns seen with lacZ constructs in the paper. In P{Scr-GAL4.1}, two enhancer fragments drive GAL4 expression. One is an 8.5 kb BamHI-EcoRI fragment encompassing the first exon and intron of Scr. The second is a 0.8 kb XbaI-HindIII fragment originating in the region between Scr and ftz. These positive regulatory elements are depicted in Figure 7 of Gindhart et al. The order of elements in the construct is 0.8 kb-8.5 kb-GAL4. This construct provides GAL4 expression in the embryonic labial and T1 segments as well as good anterior midgut expression. P{Scr-GAL4.1}J10 is a homozygous viable and fertile, second chromosome insertion. In P{Scr-GAL4.2}, three enhancer fragments drive GAL4 expression. The 8.5 and 0.8 kb fragments in P{Scr-GAL4.1} are present. A 3.0 kb XbaI-HindII fragment is also present that originated from the 10 kb XbaI negative regulatory element located 40-50 kb upstream of Scr shown in Figure 7 of Gindhart et al. The order of elements in the construct is 3.0 kb-0.8 kb-8.5 kb-GAL4. It provides spotty embryonic labial, T1 and anterior midgut expression. P{Scr-GAL4.2}1-1 is a homozygous and hemizygous viable and fertile, X chromosome insertion. In P{Scr-GAL4.3}, three enhancer fragments drive GAL4 expression. The 8.5 and 0.8 kb fragments in P{Scr-GAL4.1} are present. An 8.9 kb HindIII-EcoRI fragment originating in the region between ftz and Antp is also present. It is depicted in Figure 7 of Gindhart et al. as overlapping 3.7 kb HindIII and 7.0 kb EcoRI fragments. The order of elements in the construct is 8.9 kb-0.8 kb-8.5 kb-GAL4. The construct provides strong embryonic labial and T1 expression and weak anterior midgut expression. P{Scr-GAL4.3}1-1 is a second chromosome insertion. In P{Scr-GAL4.4}, four enhancer fragments drive GAL4 expression. The 3.0 kb, 8.9 kb, 0.8 kb and 8.5 kb fragments in the other constructs are arranged in the order 3.0 kb-8.9 kb-0.8 kb-8.5 kb-GAL4. The construct provides robust embryonic labial, T1 and anterior midgut expression. P{Scr-GAL4.4}1-3 is a homozygous viable and fertile, second chromosome insertion. The constructs were transformed using pP{CaSpeR-3}.
