Figure 1: Identification of taste receptors required for L-canavanine avoidance.
From: The full repertoire of Drosophila gustatory receptors for detecting an aversive compound
(a) An RNAi screen of 58 UAS–Gr RNAi lines and 13 UAS–Ir RNAi lines for defects in L-canavanine avoidance. We drove expression of the RNAi lines using the Gr33a–GAL4, and included UAS–Dcr2 (Dicer2) to improve the efficacy of the RNAi. The dashed line indicates no preference. See the Methods section (fly stocks) for the list of stocks screened. (b) Two-way choice assays after knocking down Gr98b using two different RNAi lines. The control consisted of UAS–Dcr2;Gr33a–GAL4 flies without the RNAi transgenes. RNAi stock numbers (VDRC) are indicated within the bars. n=5 for each genotype. **P<0.01 (analysis of variance (ANOVA) with post hoc Tukey test). (c) Cartoon showing the strategy for creating the Gr98a1 allele by ends-out homologous recombination. The arrowheads indicate the genomic PCR primers used to confirm the Gr98b deletion. A 543 bp band present in control flies was absent in Gr98b1. (d) Two-way choice assays to test whether Gr98b1 displayed a deficit in L-canavanine avoidance. To test for rescue of the Gr98b1 phenotype, we expressed the Gr98b cDNA in the Gr98b1 background using the Gr66a–GAL4, the Gr8a–GAL4 and the Gr98b–GAL4. n=5 for each genotype. **P<0.01 (ANOVA with post hoc Tukey test). (e) Two-way choice assays to test for avoidance of Gr98b1 flies in response to the indicated bitter chemicals. The flies were given a choice between 1 mM sucrose and 5 mM sucrose plus the following aversive compounds: 0.5 mM papaverine (PAP), 0.5 mM strychnine (STR), 0.1 mM denatonium (DEN), 0.05 mM berberine (BER), 0.1 mM lobeline (LOB), 5 mM caffeine (CAF), 0.2% N,N-diethyl-m-toluamide (DEET), and 0.5 mM quinine (QUIN). n=4–7 for each genotype. All data are mean±s.e.m.
