Fig. 4. Requirement of conserved DNA binding sites in homology region-c (HR-c) on floor plate and notochord expression. Alignment of HR-c sequences from mouse, human, chicken and zebrafish is shown at the top. Conserved sequences are shaded in gray. DNA recognition sequences matching the consensus for homeobox (blue), Foxh1 (green), T-box (pink) and Foxa (yellow) transcription factors are shown. (A-E) X-gal staining of transgenic embryos at 9.5 dpc carrying reporter constructs with (A) wild-type Rc9, or (B-E) mutant DNA binding sites. Adjacent to each embryo is a transverse section through lumbar regions of the spinal cord. Underneath each figure is a schematic of the reporter construct. The table to the right indicates the total number of transgenic embryos generated for each construct and their patterns of expression. The arrow in B points to the floor plate, which is devoid of X-gal staining. NC, notochord.