Annotation of enhancers at limb-associated loci. (A) The ZRS (green oval) is the only limb enhancer called at the Shh locus. The expression pattern of Shh is indicated in purple in the embryo at the upper left corner of the scheme. (B) Number of tissues and/or time points (samples) where a specific putative enhancer is identified. Most of the putative enhancers are found solely in one sample and only a limited fraction is found in all of them. (C) Pairwise comparisons of enhancers’ reproducibility between tissues. The numbers represent the fraction of enhancers predicted in both tissues and/or time points. (D) Approximately 10% of the predicted limb enhancers have been tested in a LacZ assay by the VISTA consortium. (E) Some enhancers interact with different viewpoints, suggesting a shared regulatory activity.
