Fig. 3.

Two-way choice tests showing that Gr64a was required for the behavioral responses to multiple sugars. PI values of 1.0 or 0 indicate complete preferences for one or the other tastant, and a PI of 0.5 indicates a lack of preference. (A) Flies were allowed to choose between two concentrations of the same sugar (sucrose or fructose). (B) Gr64a was not required for the avoidance of quinine or caffeine. The flies were given the choice between 2 mM fructose or 5 mM fructose plus either 1 mM quinine or 6 mM caffeine. (C) Two-sugar competition assay. The following fly stocks were allowed to choose between 2 mM fructose and higher concentrations of other sugars as indicated: (i) wild type (Canton S), (ii) Gr64^ab, and (iii) Gr64^ab flies containing the Gr5a-GAL4;UAS-Gr64a transgenes. The dashed line indicates a PI of 0.5. Statistically significant differences from wild type were checked by using the unpaired Student t test (**, P < 0.01).