Fig. 5. Identification of a functional vHNF1 binding site in element B. (A) Alignment of element B chick and mouse nucleotide sequences showing the presence of a putative vHNF1-binding site (boxed) within a highly conserved region. Conserved residues are indicated with a dash in the mouse sequence. The mutations introduced into the vHNF1 site are indicated above the box. (B) Bandshift analysis of wild-type and mutant chick elements B (cB). Extracts from control (c) or human vHNF1-expressing cells, in the presence or absence of an antibody against vHNF1 were used. The position of the specific complexes is indicated by a black arrow. The supershifted complex is marked by a white arrow. (C,D) Chick embryos analysed by X-gal staining after electroporation with constructs containing the wild-type (C) or mutant versions (D) of chick element B driving the ß-globin promoter-lacZ reporter. FP, free probe; ov, otic vesicle.