Fig. 2. Isolation of a minimum enhancer recapitulating Ci-sFRP1/5 expression. (A) Ci-sFRP1/5 locus in the Ciona intestinalis genome, showing the 5' flanking region and the first two exons. Coding/non coding conserved regions between C. intestinalis and C. savignyi are shown in white/pink. The scheme shows the position of the distal sFRP-1067 and proximal fragments tested in vivo. (B) Schematic view of the regulatory elements (with their length in brackets) tested at the 110-cell stage. With the exception of sFRP-1067, which includes the endogenous minimal promoter, all constructs were placed in front of the Cibrachyury minimal promoter. (a-c) Representative X-gal staining for embryos electroporated with the indicated DNA (percentages correspond to embryos electroporated with sFRP-640, sFRP-95 and sFRP-67 respectively). (a,c) Animal view, anterior towards the top. (b) Anterior view, animal to the top. (C) Alignment of the C. intestinalis and C. savignyi sequences of the sFRP-118 element, with putative Fox binding sites framed in red.