Figure 2. Obp49a mutants displayed reduced avoidance to sucrose/bitter mixtures.

Two-way choice behavioral assays were performed by allowing the flies to choose between 1 mM sucrose versus 5 mM sucrose/aversive chemical cocktails. (A and B) Screen for Obps required for gustatory avoidance of papaverine and berberine. Gr33a¹ was included as a positive control. (C–H) Testing for requirements for Obp49a for avoidance of a variety of sucrose/bitter cocktails. Both Obp49a¹ and Obp49a^D showed similar defects in bitter avoidance. To test for rescue of the Obp49a^D phenotype, we expressed an Obp49a⁺ transgene (UAS-Obp49a) in thecogen cells (nompA-GAL4). The numbers of behavioral tests are indicated. Shown are the means ±SEM. The asterisks indicate statistically significant differences (**p<0.01) from wild-type flies (see also Figure S2).