Fig. 2. Modifiers of the reference eye phenotype induced by the GAP domain of RacGAP(84C). Heads from female flies raised at 25°C (A-L) or 20°C (M-P) were viewed by scanning electron microscopy. B,D,F,H,J,L,N,P are higher magnifications of parts of A,C,E,G,I,K,M,O, respectively. (A,B) GMRGal4/UAS-lacZ control flies. (A) The eye surface is convex and of characteristic size and shape. (B) Each ommatidium is uniform and round and there are regular polarised inter-ommatidial bristles. (C,D) GMRGal4,UAS-GAP17/+ flies. (C) Reference rough eye phenotype. (D) Ommatidia are flattened, inter-ommatidial bristles are disoriented, of variable length, and occasionally absent. (E-H) Suppressor lines showing a more wild-type eye in size, shape, roundness and surface texture. Ommatidial architecture is basically restored, and inter-ommatidial bristles are nearly normal in number, length and polarity. (E,F) GMRGal4,UAS-GAP17/EP(2)386 flies misexpressing MESR4. (G,H) GMRGal4,UAS-GAP17/+; EP(3)3319/+ flies misexpressing Cdi/TESK1. (I-P) Enhancer lines. (I,J) GMRGal4,UAS-GAP17/EP(2)2072 flies misexpressing AKAP200. (I) Strong defects are apparent posteriorly corresponding to a black patch when viewed by optical microscopy. (J) Ommatidia are collapsed with distinct borders, except in rare cases of fusion. (K,L) GMRGal4,UAS-GAP17/EP(2)587 flies misexpressing the kinase Grapes. (K) Reduced eye size. (L) Fusion of ommatidial units and loss of bristles. (M,N) GMRGal4/EP(2)2299 flies misexpressing Beach at 20°C exhibit slightly rough eye surface and occasional fusion of ommatidia. (O,P) GMRGal4/EP(2)2299; rn²⁰/+ flies have strongly affected eyes with a rough surface, reduced size (O) and fused ommatidial units (P) (whereas rn²⁰/+ flies appear normal; not shown).