Fig. 1. The cis-regulatory region of Abd-B. (A) The Abd-B cis-regulatory region. The arrows are a graphical illustration of the targeting of each cis-regulatory domain to the Abd-Bm promoter (Boulet et al., 1991). The iab-6, iab-7 and iab-8 cis-regulatory domains interact with the Abd-Bm promoter in PS11/A6, PS12/A7 and PS13/A8, respectively. (B) The wild-type expression pattern of Abd-B in the embryonic CNS is characterized by an anterior-to-posterior increasing step gradient in the level of Abd-B. (C,D) Molecular maps of the Fab-7 and Fab-8 region (upper line). The boundary deletions mimicked are shown on the middle line and the final conversion products are shown on the bottom line.