Figure 5.

In vivo effects of MEF2 sites inactivation. Diagrams indicate the fragments extent, and status, mutated (black) or native (white) of each MEF2 site. (A–C) Transgenic embryos. Note total absence of signal at this stage when the three MEF2 sites are mutated (C), indicating that no additional MEF2 sites, active in the embryo, exist within the IRE fragment. (D–F) Somatic larval muscles. Note the progressive reduction of expression as individual sites are mutated, albeit maintaining a residual activity when the three sites are inactivated. These observations indicate that MEF2 is necessary for initiation, but not maintenance, of wup A basal transcription. (G–I) Adult leg muscles. Note the same effect of mutated MEF2 sites as in the embryo. MEF2 mutations are the same as in band shift assays (see Supplementary Material).