|
Fig. 2 Gal4 drives strong expression in stable transgenic lines and can be inhibited by Gal80. Confocal maximum projections of 72 hours postfertilization (hpf) embryos; ventral views, anterior to the top. Embryos are heterozygous for the genotypes shown. Arrow points to ectopic green fluorescent protein (GFP) expression in eyes driven by Gal4-VP16 (A,D) not noted using native Gal4 (E). A–C: Live embryos imaged with identical laser power settings, showing that Gal4-driven expression (B) is stronger than a direct enhancer:GFP construct (C) and is comparable to Gal4-VP16-driven expression (A). D–F: Immunohistochemistry for GFP in fixed embryos again shows that Gal4-dependent expression (E) is comparable to Gal4-VP16 (D), but has minimal expression in other tissues (such as eye muscles, arrow). F: The original transgenic enhancer line Tg(otpb.A:egfp)zc48 shows dimmer expression compared with Gal4-driven expression in E. G: A weakly expressing allele of elavl3:Gal80 only partially inhibits Gal4-dependent transgene expression. H: A strongly expressing elavl3:Gal80 allele completely inhibits Gal4-dependent expression. Insets for G and H show relative levels of Gal80 in situ expression. I: Gal80 is unable to inhibit Gal4-VP16-driven expression. Scale bar = 50μm.