Fig. 2. Dvir rho^4.2 carries a minimal enhancer activity accounting for the endogenous rho expression pattern during DA formation. (A,B) D. virilis rho mRNA was detected in a V-shaped stripe missing its apex at stage 10B (A), and at stage 12 its distribution was restricted to the four domains where the four DAs later form (B). (C,D) The Dvir rho^4.2 enhancer drove the expression of GFP in a pattern similar to that of the endogenous rho in D. virilis. At stage 10B, a Vshaped stripe missing its apex was observed (C), and then at stage 12, the GFP reporter was expressed where the four DAs would later form (D). White arrowheads and brackets indicate the cells forming the anterior and posterior DAs, respectively (B,D). (E-G) Confocal images of the GFP reporter expression driven by the Dvir rho^4.2 enhancer and of endogenous Broad-Complex (BR-C) expression. The expression of Dvir rho^4.2-GFP (green in E and G) and BR-C (magenta in F and G) was mutually exclusive at stage 10B. G is a merged image of E and F.