title: Involvement of the Drosophila taurine/aspartate transporter dEAAT2 in selective olfactory and gustatory perceptions.
abstract: Excitatory amino acid transporters (EAATs) are membrane proteins involved in the uptake of neurotransmitter amino acids in the nervous system. The Drosophila dEAAT2 gene was previously described to encode a taurine/aspartate transporter. To analyze further the expression pattern and physiological function of this protein, we generated transgenic flies containing either the dEAAT2 promoter region fused to GAL4 (dEAAT2-GAL4) or a transgene allowing expression of a dEAAT2::GFP fusion protein (UAS-dEAAT2::GFP). We observed that dEAAT2-GAL4 expresses green fluorescent protein (GFP) in neurons in central and peripheral structures of third-instar larvae and adult flies. Labeled neurons were found in olfactory and gustatory pathways, in which dEAAT2::GFP was detected from the dendrites of the sensory neurons up to the first- and second-order centers. dEAAT2-GAL4 is also expressed in mechanosensory neurons. We found that a viable piggyBac insertion strain disrupts dEAAT2 expression. This mutant appears morphologically normal and presents no locomotor or phototaxis impairments; however, its brain taurine level is significantly reduced compared with that of wild-type flies. The dEAAT2 mutant showed decreased avoidance behavior in the presence of high concentration of propionic acid compared with wild-type flies, but no modification of the avoidance response to benzaldehyde. In gustatory tests, both mutant and control flies were normally attracted to sucrose; however, the dEAAT2 mutant presented a higher salt sensitivity, being repulsed by low and high salt concentrations. Therefore, we conclude that dEAAT2 does function as a taurine transporter in vivo and that this protein is physiologically required for the sensory perception of specific environmental molecules.
authors.affiliation: Developmental Biology Institute of Marseille (IBDML), Centre National de la Recherche Scientifique (CNRS) UMR 6216, Université Aix-Marseille II-III, 13288 Marseille cedex 9, France. marie-therese.besson@univmed.fr
authors.forename: M T
authors.initials: MT
authors.lastname: Besson
authors.forename: I
authors.initials: I
authors.lastname: Sinakevitch
authors.forename: C
authors.initials: C
authors.lastname: Melon
authors.forename: M
authors.initials: M
authors.lastname: Iché-Torres
authors.forename: S
authors.initials: S
authors.lastname: Birman
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001522:Behavior, Animal / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000502:physiology*; D027342:Excitatory Amino Acid Transporter 2 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D008297:Male; D040542:Mechanotransduction, Cellular; D055696:Olfactory Perception / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000166:cytology / Q000378:metabolism; D012903:Smell / Q000502:physiology; D013649:Taste / Q000502:physiology; D055697:Taste Perception / Q000502:physiology*; D013654:Taurine / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; C421004:Eaat2 protein, Drosophila; D027342:Excitatory Amino Acid Transporter 2; D011993:Recombinant Fusion Proteins; D013654:Taurine