Gustatory Receptors Required for Avoiding the Insecticide l-Canavanine

• DOI: 10.1523/jneurosci.4630-11.2012
• Publication Date: 2012-01-26T03:32:26Z
• Authors: Youngseok Lee; Min Jung Kang; Jaewon Shim; Chae Uk Cheong; Seok Jun Moon; Craig Montell
• Keywords: 0301 basic medicine; Insecticides; Action Potentials; Receptors, Cell Surface; 3. Good health; Animals, Genetically Modified; Canavanine; Protein Subunits; 03 medical and health sciences; Mutation; Avoidance Learning; Animals; Drosophila Proteins

Insect survival depends on contact chemosensation to sense and avoid consuming plant-derived insecticides, such asl-canavanine. Members of a family of ∼60 gustatory receptors (GRs) comprise the main peripheral receptors responsible for taste sensation inDrosophila. However, the roles of mostDrosophilaGRs are unknown. In addition to GRs, a G protein-coupled receptor, DmXR, has been reported to be required for detectingl-canavanine. Here, we showed that GRs are essential for responding tol-canavanine and that flies missing DmXR displayed normall-canavanine avoidance andl-canavanine-evoked action potentials. Mutations disrupting eitherGr8aorGr66aresulted in an inability to detectl-canavanine. We found thatl-canavanine stimulated action potentials in S-type sensilla, which were whereGr8aandGr66awere both expressed, but not inGr66a-expressing sensilla that did not expressGr8a.l-canavanine-induced action potentials were also abolished in theGr8aandGr66amutant animals.Gr8awas narrowly required for responding tol-canavanine, in contrast toGr66a, which was broadly required for responding to other noxious tastants. Our data suggest that GR8a and GR66a are subunits of anl-canavanine receptor and that GR8a contributes to the specificity forl-canavanine.