Fig. 2. Loss of hyd induces ectopic hh expression in the eye disc. All panels show third instar eye discs. (A-D) Anti-Elav staining in red, anti-ß-galactosidase staining, reflecting hh-lacZ expression, in blue, and GFP in green. (A-C) hyd^K7.19 clones (marked by lack of GFP expression in C); (D) wild type. hh is misexpressed anterior to its normal domain in hyd mutant clones. (E) hyd^K7.19 clones made in a Minute background, showing hh-lacZ expression in green. hh is misexpressed throughout the eye disc. The two portions of the eye-antennal disc are indicated: e, eye disc; a, antennal disc. (F) In situ hybridization with a hyd antisense probe. hyd is predominantly expressed anterior to the furrow. The sense probe showed only very faint non-specific staining (not shown). (G-I) hyd^K7.19, ato^IH3 clones positively marked by GFP expression in (H,I) are stained with anti-Elav in red and anti-ß-galactosidase, reflecting hh-lacZ expression, in blue. Lack of ato prevents differentiation, but not hh expression, within the hyd clones (arrows); ectopic hh then leads to differentiation of surrounding wild-type tissue.