Fig. 4. Analysis of the dap regulatory region. The dap genomic regions of D. melanogaster and D. virilis were isolated, sequenced and compared. The coding sequences are indicated by black boxes. Red boxes indicate blocks of high sequence similarity within the non-coding regions. The putative transcriptional start site in the D. melanogaster gene is indicated by an arrow. Distances (kb) from this start site are given by negative numbers. The green box indicates the extent of the deletion present in dap⁹. Black lines indicate the sequences that were present in the various transgene constructs of the dap-g and dap-gm series (1gm, 2g, 3gm, 4gm, 5gm, 6gm). Blue lines indicate the sequences that were present in the lacZ reporter constructs of the dap-l series (1l to 15l, and 15l-A8). The region present in the transgene dap-5l and the transgenes used for the dissection of this region are shown at a higher resolution. Gray boxes indicate distinct cis-regulatory elements driving expression in the interstitial cell precursors (ICP), tracheal pits (TP), peripheral nervous system (PNS), central nervous system (CNS), epidermis, gut and in the prospective posterior spiracle region in the abdominal segment 8 (A8). The table summarizes the results of the dissection of the 5l region in more detail. Expression of the relevant transgenes (dap-6l to dap-15l and dap-15l-A8) in epidermis, gut and prospective posterior spiracles region (A8) was scored as either particularly strong (++), strong (+) or absent (–). The D. melanogaster and D. virilis sequences present in the conserved block required for high level expression in the prospective posterior spiracle region (A8) is shown at the bottom. Red arrows indicate potential Abdominal B-binding sites, and the positions matching the Abdominal B-binding site consensus (TTTATGGC) (Ekker et al., 1994) are written with red letters. Other positions of identity between D. melanogaster and D. virilis are written in green letters. For details see text.