Figure 1.

Genetic interactions between fru and hb in the compound eye. A, The Canton-S wild-type eye. B, The eye with fru⁺(type B) overexpression under the control of GMR-Gal4. C, The fru⁺-dominant phenotype alleviated by heterozygous hb¹². D, The eye with ttk⁺ overexpression. E, The ttk⁺-dominant phenotype in heterozygous hb¹². F, The rough eye induced by hb⁺ overexpression via GMR-Gal4. G, The eye with simultaneous overexpression of fru⁺ and hb⁺. H, I, An eye mosaic for hb^B observed with scanning electron microscopy (H) or with light microscopy to identify the heterozygous (red) and homozygous (white) tissues (I). The genotype of the test flies was y w ey-flp GMR-lacZ;;FRT82B hb^B1/FRT82B w⁺. The scanning microscopic images are shown at lower (top) and higher (bottom) magnifications. Scale bars: top, 100 μm; bottom, 10 μm. J, The list of modifiers of fru isolated in our screen. The fly lines found to be positive are shown with the Bloomington stock numbers, the names of genes affected, the full description of genotypes and the observed effects on the eye expressing one of the three fru isoforms. The enhancing effects are indicated with “+” marks and the suppressing effects with “−” marks. The strength of the modifying effects is indicated by the number of symbols (lines marked with three symbols are the strongest modifiers). “/”, not tested.