Fig. 3. Expression of hbs in embryonic tissues and larval imaginal discs. (A) A late stage 10 embryo has the mesectodermal cells aligned at the midline (arrowhead) and is hbs positive. Lateral patches of mesodermal cells (arrow) also express hbs. (B) This pattern is revealed at the protein level with the Hbs antibody. Arrow and arrowhead indicate equivalent tissues from A. (C) hbs-positive cells lie posterior and internal to the posterior commissure (pc) as it and the anterior (ac) are developing during stage 12. (D) By stage 14, only a subset of cells below the pc are still Hbs positive (arrowheads). (E) Stage 13 embryo. hbs is expressed by fusion competent myoblasts. (F) hbs is not expressed in muscle founder cells as shown in the age matched Notch mutant embryo. (G) At stage 11 hbs is expressed in fusion competent myoblasts (arrowheads) but not the Kruppel-positive founder cell (arrow). (H) Expression of hbs in the muscle attachment sites of a stage 14 embryo. (I) hbs is expressed in cells within and behind the morphogenetic furrow of the larval eye/antennal disc. (J) In the larval brain, hbs is expressed in the optic lobes in the locations where the photoreceptors terminate (arrows). In the wing disc (K), hbs expression is present in stripes that bound the presumptive wing margin (arrowhead), the stripes corresponding to wing veins L3 and L4 (downward arrows) and L0 and L1 (horizontal arrow). (L) In the leg disc, there are broad concentric circles of hbs.
