Fig. 6. col transcription in the DA3 muscle precursor depends upon a Nau and a potential Col-binding site in the DA3 muscle CRM. (A) Col and P2.6cl expression in wt Drosophila embryos at stage 15, visualised by Col (red) and β-gal (green in the right and white in the left panel) antibody staining. (B,C) P2.6cl expression is lost when either the putative EBF/Col- (B) or Nau- (C) binding site present in the DA3 muscle CRM is mutated. Red dots in A and C correspond to Col expression in md neurons. (D) Col expression in all FCs (rp298-Gal4/UAS-col) induces ectopic P2.6cl expression in the VL1 (arrow) and DA2 (dot) muscles, as visualised by β-gal immunostaining; the arrowhead points to the DA3 muscle. (E) Ectopic expression of P2.6cl is not observed when the EBF/Col-binding site is mutated. (F) The consensus EBF- and MyoD-(Nau) binding sites (Huang et al., 1996; Travis et al., 1993) are represented above the predicted sites found within the DA3 muscle CRM. The mutated positions introduced in P2.6cl^col and P2.6cl^nau are shown in red.