FIGURE 7

Enhancer functions of CRMs of progenitor fate-specifying TFs. The CRM reporter vectors indicated were electroporated into chick neural tubes together with CAGGS::mCherry as a control vector. (a–j) The GFP and mCherry expression was examined at HH19–20 in the forelimb-level neural tube. (k–o) The endogenous expression of the indicated genes was examined by in situ hybridization (l, m, n) or immunohistochemistry (k, o) together with the GFP expression. These five CRMs displayed enhancer functions, although the GFP expression domains incompletely overlapped with the endogenous expression domain. Pax6-CRM induced GFP expression almost ubiquitously, but its expression was not observed in the roof plate (a, f, k). Gsx1-CRM induced GFP expression in the dorsal neural tube, but not in the more ventral region than the endogenous expression domain (b, g, l). The GFP expression domains induced by Dbx2-CRM or Irx3-CRM2 overlapped with the endogenous expression domain almost completely (c, d, h, i, m, and n). Olig2-CRM2 induced GFP expression in the intermediate to ventral region, which partially overlapped with, but was more dorsal than, the endogenous expression domain (e, j, and o). The number of embryos examined in the electroporation experiments is presented in Table S5. Scale bar: 100 μm