Youngseok Lee, Min Jung Kang, Jaewon Shim, Chae Uk Cheong, Seok Jun Moon, Craig Montell
Department of Biological Chemistry, Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
The Journal of neuroscience : the official journal of the Society for Neuroscience 2012 Jan 25Insect survival depends on contact chemosensation to sense and avoid consuming plant-derived insecticides, such as L-canavanine. Members of a family of ∼60 gustatory receptors (GRs) comprise the main peripheral receptors responsible for taste sensation in Drosophila. However, the roles of most Drosophila GRs are unknown. In addition to GRs, a G protein-coupled receptor, DmXR, has been reported to be required for detecting L-canavanine. Here, we showed that GRs are essential for responding to L-canavanine and that flies missing DmXR displayed normal L-canavanine avoidance and L-canavanine-evoked action potentials. Mutations disrupting either Gr8a or Gr66a resulted in an inability to detect L-canavanine. We found that L-canavanine stimulated action potentials in S-type sensilla, which were where Gr8a and Gr66a were both expressed, but not in Gr66a-expressing sensilla that did not express Gr8a. L-canavanine-induced action potentials were also abolished in the Gr8a and Gr66a mutant animals. Gr8a was narrowly required for responding to L-canavanine, in contrast to Gr66a, which was broadly required for responding to other noxious tastants. Our data suggest that GR8a and GR66a are subunits of an L-canavanine receptor and that GR8a contributes to the specificity for L-canavanine.
Youngseok Lee, Min Jung Kang, Jaewon Shim, Chae Uk Cheong, Seok Jun Moon, Craig Montell. Gustatory receptors required for avoiding the insecticide L-canavanine. The Journal of neuroscience : the official journal of the Society for Neuroscience. 2012 Jan 25;32(4):1429-35
PMID: 22279227
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