Fig. 5

Mutation of TCF/Lef sites within the Bf-Gsx-Up1 + 2b construct. a Relative positions of TCF/Lef sites within the Bf-Gsx-Up2b, Bf-Gsx-Up1 and Bf-Gsx-Up1 + 2b regulatory regions. An additional TCF/Lef site within the 2b region is added in the Bf-Gsx-Up1 + 2b construct. ‘+’ symbols denote the presence of LacZ expression in the corresponding construct, with ‘++’ denoting high LacZ expression and ‘+++’ very high LacZ expression, whereas ‘–‘ denotes the absence of LacZ expression. (b) Schematic showing the DNA sequence of TCF/Lef site 3 before and after mutagenesis. Pink sequence denotes the TCF/Lef site ‘core’ sequence before mutation, whereas light gray sequence denotes the TCF/Lef site ‘core’ sequence after mutation. (c) Comparison of CNS expression incidence in the Bf-Gsx-Up1 + 2b construct with TCF/Lef binding motif mutants. The numbers of embryos displaying either nerve cord only, sensory vesicle only, or the nerve cord with sensory vesicle LacZ expression patterns have been recorded both as a percentage of the total number of embryos that developed and as raw numbers of embryos expressing LacZ for each domain alongside the total number of embryos that developed. Pink boxes denote the positions of intact TCF/Lef sites, whereas white crossed boxes indicate the positions of mutated TCF/Lef sites. (d) Schematic showing the partial division of function into ‘nerve cord’ and ‘sensory vesicle’ domains across the Bf-Gsx-Up1 + 2b regulatory element. (d i) Shows the bias of the 3' region and TCF/Lef sites 1 and 2 to drive nerve cord expression over sensory vesicle expression whilst (d ii) shows the bias of the 5' region and TCF/Lef site 3 to drive sensory vesicle expression over nerve cord expression