title: A molecular and neuronal basis for amino acid sensing in the Drosophila larva.
abstract: Amino acids are important nutrients for animals, reflected in conserved internal pathways in vertebrates and invertebrates for monitoring cellular levels of these compounds. In mammals, sensory cells and metabotropic glutamate receptor-related taste receptors that detect environmental sources of amino acids in food are also well-characterised. By contrast, it is unclear how insects perceive this class of molecules through peripheral chemosensory mechanisms. Here we investigate amino acid sensing in Drosophila melanogaster larvae, which feed ravenously to support their rapid growth. We show that larvae display diverse behaviours (attraction, aversion, neutral) towards different amino acids, which depend upon stimulus concentration. Some of these behaviours require IR76b, a member of the variant ionotropic glutamate receptor repertoire of invertebrate chemoreceptors. IR76b is broadly expressed in larval taste neurons, suggesting a role as a co-receptor. We identify a subpopulation of these neurons that displays physiological activation by some, but not all, amino acids, and which mediate suppression of feeding by high concentrations of at least a subset of these compounds. Our data reveal the first elements of a sophisticated neuronal and molecular substrate by which these animals detect and behave towards external sources of amino acids.
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Vincent
authors.initials: V
authors.lastname: Croset
authors.affiliation: Leibniz Institute for Neurobiology (LIN), Department Genetics of Learning and Memory, Brenneckestrasse 6, 39118 Magdeburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schleyer
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: J Roman
authors.initials: JR
authors.lastname: Arguello
authors.affiliation: Leibniz Institute for Neurobiology (LIN), Department Genetics of Learning and Memory, Brenneckestrasse 6, 39118 Magdeburg, Germany.|Otto von Guericke University Magdeburg, Institute for Biology, Behavior Genetics, Universitätsplatz 2, 39106 Magdeburg, Germany.|Center of Behavioural Brain Science (CBBS), Universitätsplatz 2, 39106 Magdeburg, Germany.
authors.forename: Bertram
authors.initials: B
authors.lastname: Gerber
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Richard
authors.initials: R
authors.lastname: Benton
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001921:Brain / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D004330:Drosophila / Q000254:growth & development / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000378:metabolism; D016296:Mutagenesis; D009474:Neurons / Q000378:metabolism*; D058468:Receptors, Ionotropic Glutamate / Q000235:genetics / Q000378:metabolism; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D029721:Drosophila Proteins; C581929:IR76b protein, Drosophila; D058468:Receptors, Ionotropic Glutamate; D015222:Sodium Channels; D002118:Calcium