Fig. 3. Loss of JAK/STAT signaling results in changes in eye disc morphology and ectopic wg expression. Clones were generated using ey-flp in a Minute (A-E) or non-Minute (F,H,I) background. (A,B) A third instar dpp-lacZ; + M⁺ (A) or dpp-lacZ; stat92E^85C9 M⁺ (B) eye disc. Heterozygous tissue (green), Elav (red), dpp-lacZ (blue). dpp is absent from the dorsal domain of stat92E^85C9 M⁺ eye discs (B). (C) A third instar dpp-lacZ; stat92E^85C9 M⁺ eye disc. Heterozygous tissue (green), Wg (red), dpp-lacZ (blue). dpp is lost from the dorsal domain of the eye disc and Wg expression is expanded into this region (yellow arrow). The morphogenetic furrow [marked by dpp-lacZ (anti-ß-Gal) expression] moves only through the ventral region of stat92E^85C9 M⁺ eye discs (B,C); these discs also exhibit abnormal dorsal outgrowths (white arrows in B,C). (D,E) A third instar wg-lacZ; + M⁺ (D) or wg-lacZ; stat92E^85C9 M⁺ (E) eye disc. Heterozygous tissue (green), wg-lacZ (anti-ß-Gal, red), Elav (blue). wg is ectopically expressed in stat92E^85C9 M⁺ discs and expansion of both the dorsal wg domain and the ventral wg domain (arrowhead) is evident (E). (F) A third instar wg-lacZ; stat92E^85C9 eye disc. Wild-type tissue (green), wg-lacZ (red), Dlg (blue). wg is expanded in stat92E^85C9 clones (arrow). (G) A third instar hop^M13/Y; wg-lacZ eye disc. X-gal staining indicates that wg is ectopically expressed throughout most of the eye disc in hop mutants. (H,I) Dorsal views of adult heads. X-Gal staining of adults carrying wg-lacZ (blue) with an FRT^82B (control) (H) or stat92E^85C9 (I) chromosome. Ectopic wg is observed in stat92E^85C9 clones (marked by white ommatidia) in the eye field, frequently at the base of ectopic outgrowths (arrows) (I). This is never seen in wild-type (FRT^82B) clones (H).