Fig. 6

Mutation of all TCF/Lef sites abolishes CNS expression and reveals a latent repressive function that increases with regulatory element length. Images of mid tailbud Ciona embryos represent the maximal example of pCES ‘background’ LacZ expression for Bf-Gsx-Up1cΔ1Δ2, Bf-Gsx-Up1Δ1Δ2 and Bf-Gsx-Up1 + 2bΔ1Δ2Δ3 respectively. The numbers and percentage of embryos displaying either of the CNS LacZ expression domains examined in Figs. 2, 4 and 5 along with those displaying only pCES background expression. Numbers of embryos showing either pattern 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. White crossed boxes indicate the positions of mutated TCF/Lef sites. The blue graduated arrow represents the decrease in pCES background expression associated with an increase in construct length from Bf-Gsx-Up1cΔ1Δ2 to Bf-Gsx-Up1Δ1Δ2, to Bf-Gsx-Up1 + 2bΔ1Δ2Δ3