PMID: identifiant
de la référence Pubmed : |
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 (19564899)  |
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| titre : |
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Plant insecticide L-canavanine repels Drosophila via the insect orphan GPCR DmX. |
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| auteur(s) : |
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Christian Mitri1, Laurent Soustelle1, Bérénice Framery1, Joël Bockaert1, Marie-Laure Parmentier1, Yves Grau ( ) 1 |
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| laboratoire : |
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| résumé : |
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For all animals, the taste sense is crucial to detect and avoid ingesting toxic molecules. Many toxins are synthesized by plants as a defense mechanism against insect predation. One example of such a natural toxic molecule is L-canavanine, a nonprotein amino acid found in the seeds of many legumes. Whether and how insects are informed that some plants contain L-canavanine remains to be elucidated. In insects, the taste sense relies on gustatory receptors forming the gustatory receptor (Gr) family. Gr proteins display highly divergent sequences, suggesting that they could cover the entire range of tastants. However, one cannot exclude the possibility of evolutionarily independent taste receptors. Here, we show that L-canavanine is not only toxic, but is also a repellent for Drosophila. Using a pharmacogenetic approach, we find that flies sense food containing this poison by the DmX receptor. DmXR is an insect orphan G-protein-coupled receptor that has partially diverged in its ligand binding pocket from the metabotropic glutamate receptor family. Blockade of DmXR function with an antagonist lowers the repulsive effect of L-canavanine. In addition, disruption of the DmXR encoding gene, called mangetout (mtt), suppresses the L-canavanine repellent effect. To avoid the ingestion of L-canavanine, DmXR expression is required in bitter-sensitive gustatory receptor neurons, where it triggers the premature retraction of the proboscis, thus leading to the end of food searching. These findings show that the DmX receptor, which does not belong to the Gr family, fulfills a gustatory function necessary to avoid eating a natural toxin. |
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| domaine : |
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Sciences du Vivant/Biochimie, Biologie Moléculaire
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langue du texte
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Anglais |
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| ISSN : |
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1544-9173 |
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| type de publication : |
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Articles dans des revues avec comité de lecture |
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| DOI : |
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10.1371/journal.pbio.1000147 |
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| journal : |
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| Audience : |
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internationale |
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| date de publication : |
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30/06/2009 |
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date de publication
électronique : |
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30/06/2009 |
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| volume : |
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7 |
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| numéro : |
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6 |
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| page, identifiant, ... : |
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e1000147 |
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| Descripteur(s) MeSH : |
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Animals – Avoidance Learning – Canavanine – Cell Line – Chemoreceptor Cells – Drosophila Proteins – Drosophila melanogaster – Feeding Behavior – Gene Expression – Gene Expression Profiling – Humans – Immunohistochemistry – In Situ Hybridization – Insecticides – Mutation – Plants – RNA Interference – Receptors – Cell Surface – G-Protein-Coupled – Reverse Transcriptase Polymerase Chain Reaction |
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| contrat, financement : |
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This work was supported by fellowships from the Ministère de la Recherche and the Fondation pour la Recherche Médicale to CM, a Centre National de la Recherche Scientifique (CNRS) postdoctoral fellowship to LS, by the ANR grant DROSDYN to MLP and by grants from the CNRS and Institut National de la Santé et de la Recherche Médicale (INSERM) to the Institut de Génomique Fonctionnelle. The small animal imaging core facility (http://ipam.igf.cnrs.fr/) was supported by grants from the National Biophotonics and Imaging Platform (Ireland), Réseau National des Génopoles, Institut Fédératif de Recherche 3 (IFR3), and Région Languedoc Roussillon |
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