Figure 5.

The human and chimpanzee sequences for 2xHAR.114 drive different activity patterns in the developing limbs of transgenic mice. (a) 2xHAR.114 is located on chromosome 20 and flanked by MYLK2 and FOXS1. The organization and details of this figure are the same as in figure 4. (b) Both the human and chimpanzee sequence produce consistent staining in the limb (white triangles) and neural tube, as well as suggestive staining in the brain. The flanking genes are known to be involved in heart development. Additional embryo images are given in electronic supplementary material, figure S1. (c) The chimpanzee sequence consistently drives more extensive activity in the limb at E11.5. The mean fraction of the forelimb stained across all LacZ positive mouse embryos with the human construct was significantly lower than with the chimpanzee construct (p = 0.004; t-test). (d) Cross sections of mouse embryonic forelimbs showing the patterns of LacZ expression (blue) driven by the human and chimpanzee 2xHAR.114 enhancers. Both enhancers have limb mesenchyme activity, but the chimpanzee enhancer has a much larger domain of activity.