Fig. 5. The jing-lacZ enhancer is expressed in the midline. lacZ expression in whole-mount embryos heterozygous for the jing-lacZ enhancer trap and stained with anti-ß-gal. (A) Strong midline jing-lacZ expression (arrow) and weaker neuroectodermal expression in stage 14 jing⁰¹⁰⁹⁴ heterozygotes (arrowhead). (B) Reduced jing-lacZ expression in the midline and neuroectoderm of jing⁰¹⁰⁹⁴ homozygotes suggests autoregulation. (C) In sim^H9/sim^H9 null mutants, jing-lacZ midline expression is not detectable (arrow) but lacZ expression still occurs in the neuroectoderm (arrowhead). (D-F) Embryos heterozygous for the jing-lacZ enhancer trap, P[prd-Gal4] and P[UAS-sim] and stained with anti-SIM (D, red), anti-ß-gal (E, green). (E) Ectopic jing-lacZ activation (arrows). (F) Merged images of D,E. (F) Activation of jing-lacZ in the ventral region of prd pair-rule stripes (arrows).