Fig. 1. Characterization of gcm-Gal4- and Coll-Gal4-induced expression pattern. (A-C) gcm-lacZ embryos stained with anti-ß-Gal antibody. ß-Gal is located in the nuclei. (A) The first signs of ß-Gal expression are detected in the hemocyte primordium at stage 8. (B) At early stage 12, ß-Gal is found in migrating macrophages (arrows) and in the glia cells (arrowheads). (C) At stage 17, ß-Gal is still present in macrophages and glia cells. (D-F) In situ hybridization showing the expression pattern of lacZ transcript in gcm-Gal4 UAS-lacZ embryos. (D) lacZ transcript is first observed in the hemocyte progenitors at late stage 8. (E) A stage 12 embryo with lacZ transcript in migrating macrophages (arrows) and glial cells (arrowheads). (F) A close-up of the lateral region of a stage 15 embryo with lacZ expression in macrophages (arrows) and epidermal stripes (vertical rows of labeled cells). (G-I) gcm-Gal4 UAS-lacZ embryos stained with anti-ß-Gal antibody. ß-Gal is located in the cytoplasm. (G) In gcm-Gal4 UAS-lacZ embryos, ß-Gal is not detected until stage 9 in the hemocyte primordium. (H) Subsequently, the expression pattern of ß-Gal mimics that of gcm-lacZ (stage 12 embryo; arrows indicate macrophages and arrowheads indicate glia cells). (I) ß-Gal expression persists in macrophages until late embryogenesis. Shown is a close-up of macrophages in the ventral region of a stage 17 embryo. (J-L) Coll-lacZ embryos stained with anti-ß-Gal antibody. (J) In Coll-lacZ embryos, ß-Gal (nuclear) becomes detectable in macrophages at stage 13, but only in an apparently random fraction of macrophages. (K) ß-Gal is detected in all macrophages by stage 15, which also display a more intense staining. This expression persists until stage 17 (L). (M-O) In situ hybridization of Coll-Gal4 UAS-lacZ embryos with a lacZ-specific probe. (M) lacZ transcript is initially detected in macrophages at stage 13, but only in a random subset of cells. (N) At stage 15, all macrophages express the lacZ transcript. The salivary glands also express lacZ (arrow). (O) lacZ expression in macrophages continues in stage 17 embryos. (P-R) Coll-Gal4 UAS-lacZ embryos stained for ß-Gal. (P) ß-Gal is first observed in stage 13 embryos in a subset of macrophages. (Q) At stage 15, all macrophages are ß-Gal positive, and ß-Gal persists until stage 17 (R).