Fig. 1. Regulatory landscape of the Abd-B gene of the BX-C. (A) Genomic map of the 3' cis-regulatory region of the Abd-B gene. The proximal and distal arrows point towards the centromere and telomere, respectively. The black numbers above the DNA line correspond to the nucleotide sequence marked in kb (SEQ89E) (Martin et al., 1995). The exons of the Abd-B transcription unit encoding the m variant are shown below the DNA line. The extent of the iab-5, 6 and 7 cis-regulatory domains are indicated by brackets, with the domain boundaries in between shown by gray circles. The red boxes on the DNA line mark the IAB5, IAB6, IAB7a, IAB7b and IAB8 initiator elements (from proximal to distal, respectively). The extent of the deletions analyzed are shown below the DNA line, in black for deletions associated with loss-of-function of phenotypes and in red for gain-of-function phenotypes. (B) The DNA line with the scales as in A is drawn again. The extent of the different restriction fragments used in transgenic constructs are shown below, with the initiator fragments drawn in red. The expression patterns directed by these initiator fragments are presented in C-F, which show embryos at the extended germ band stage, doubled stained with antibodies directed against Engrailed (brown) and the ß-Galactosidase (in blue). The parasegmental anterior border of lacZ expression (indicated by an arrow) shifts one parasegment posterior in each panel from left to right