Fig. 2. Conserved cis-regulatory elements and TF-binding sites in the DA3 muscle CRM. (A) Col expression in a stage 14 D. vir embryo (top left) and in situ hybridisation to lacZ transcripts showing expression of different D. vir and D. mel col reporter genes, as indicated in each panel. Note that P2.6-1.6cG is a Gal4/UAS-lacZ line. (B) Diagrammatic representation of the relative positions of conserved motifs, numbered from 1 to 10 and potential binding sites for Twi, Nau, Col and Mef2 in the DA3 muscle CRM (for details, see Fig. S2 in the supplementary material). (C,D) Ubiquitous hs-col driven Col expression specifically activates col-lacZ reporter genes in the VL1 muscle (white arrow), as shown here for P2.6cl (C). This is mediated by conserved cis-regulatory elements in the DA3 muscle CRM (D).