Fig. 4

Expression of hbn enhancer-Gal4 strains in the embryo. A The genomic organization of the hbn locus is shown together with the locations of fragments from the upstream, intronic and downstream regions of the hbn locus used to test enhancer activities in the respective Gal4 strains. B-G Dorsal views of the anterior parts of stage 15 Drosophila embryos. The anterior ends of the embryos are pointing towards the bottom. An anti-Hbn antibody was used to visualize the nuclear Hbn expression pattern (red). Enhancer-Gal4-driven UAS-mCD8::GFP expression in the membrane (green, C, E-G) or UAS-H2B-mRFP1 expression in the nucleus (green, D) visualize the expression patterns generated by the various enhancers. In (B) HRP was used as a marker (green). The Gal4 strain numbers are indicated, and arrowheads indicate important regions showing coexpression of Hbn and the fluorescence marker (red arrowheads, DPM region; white arrowheads, DPL region; yellow arrowheads, DAL region; orange arrowheads, DAM region; green arrowheads, supraesophageal commissure; magenta arrowheads, clypeolabrum in (G) and additional staining domains in (C)) The white arrow in (E) indicates the Hbn cells in direct proximity to the commissure. Abbreviations: DAL, dorso-anterior lateral lineages; DAM, dorso-anterior medial lineages; DPL, dorso-posterior lateral lineages; DPM, dorso-posterior medial lineages; PCN, protocerebral connective; SEC, supraesophageal commissure. For symmetrical expression patterns, domain arrowheads are only shown on the right side. (Scale bars: B-G, 25 μm)