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Mazzotta GM, Bellanda M, Minervini G, Damulewicz M, Cusumano P, Aufiero S, Stefani M, Zambelli B, Mammi S, Costa R, Tosatto SCE. Calmodulin Enhances Cryptochrome Binding to INAD in Drosophila Photoreceptors. Front Mol Neurosci 2018; 11:280. [PMID: 30177872 PMCID: PMC6109769 DOI: 10.3389/fnmol.2018.00280] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 07/24/2018] [Indexed: 12/13/2022] Open
Abstract
Light is the main environmental stimulus that synchronizes the endogenous timekeeping systems in most terrestrial organisms. Drosophila cryptochrome (dCRY) is a light-responsive flavoprotein that detects changes in light intensity and wavelength around dawn and dusk. We have previously shown that dCRY acts through Inactivation No Afterpotential D (INAD) in a light-dependent manner on the Signalplex, a multiprotein complex that includes visual-signaling molecules, suggesting a role for dCRY in fly vision. Here, we predict and demonstrate a novel Ca2+-dependent interaction between dCRY and calmodulin (CaM). Through yeast two hybrid, coimmunoprecipitation (Co-IP), nuclear magnetic resonance (NMR) and calorimetric analyses we were able to identify and characterize a CaM binding motif in the dCRY C-terminus. Similarly, we also detailed the CaM binding site of the scaffold protein INAD and demonstrated that CaM bridges dCRY and INAD to form a ternary complex in vivo. Our results suggest a process whereby a rapid dCRY light response stimulates an interaction with INAD, which can be further consolidated by a novel mechanism regulated by CaM.
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Affiliation(s)
| | - Massimo Bellanda
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | | | - Milena Damulewicz
- Department of Cell Biology and Imaging, Institute of Zoology and Biomedical Research, Faculty of Biology and Earth Sciences, Jagiellonian University, Kraków, Poland
| | - Paola Cusumano
- Department of Biology, University of Padova, Padova, Italy
| | - Simona Aufiero
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Monica Stefani
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Barbara Zambelli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Stefano Mammi
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Rodolfo Costa
- Department of Biology, University of Padova, Padova, Italy
| | - Silvio C E Tosatto
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,CNR Institute of Neuroscience, Padova, Italy
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2
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Fleischer J, Pregitzer P, Breer H, Krieger J. Access to the odor world: olfactory receptors and their role for signal transduction in insects. Cell Mol Life Sci 2018; 75:485-508. [PMID: 28828501 PMCID: PMC11105692 DOI: 10.1007/s00018-017-2627-5] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 08/09/2017] [Accepted: 08/14/2017] [Indexed: 12/26/2022]
Abstract
The sense of smell enables insects to recognize and discriminate a broad range of volatile chemicals in their environment originating from prey, host plants and conspecifics. These olfactory cues are received by olfactory sensory neurons (OSNs) that relay information about food sources, oviposition sites and mates to the brain and thus elicit distinct odor-evoked behaviors. Research over the last decades has greatly advanced our knowledge concerning the molecular basis underlying the reception of odorous compounds and the mechanisms of signal transduction in OSNs. The emerging picture clearly indicates that OSNs of insects recognize odorants and pheromones by means of ligand-binding membrane proteins encoded by large and diverse families of receptor genes. In contrast, the mechanisms of the chemo-electrical transduction process are not fully understood; the present status suggests a contribution of ionotropic as well as metabotropic mechanisms. In this review, we will summarize current knowledge on the peripheral mechanisms of odor sensing in insects focusing on olfactory receptors and their specific role in the recognition and transduction of odorant and pheromone signals by OSNs.
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Affiliation(s)
- Joerg Fleischer
- Department of Animal Physiology, Institute of Biology/Zoology, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | - Pablo Pregitzer
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Heinz Breer
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Jürgen Krieger
- Department of Animal Physiology, Institute of Biology/Zoology, Martin Luther University Halle-Wittenberg, 06120, Halle (Saale), Germany.
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3
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A Single Residue Mutation in the Gα q Subunit of the G Protein Complex Causes Blindness in Drosophila. G3-GENES GENOMES GENETICS 2018; 8:363-371. [PMID: 29158337 PMCID: PMC5765363 DOI: 10.1534/g3.117.300340] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Heterotrimeric G proteins play central roles in many signaling pathways, including the phototransduction cascade in animals. However, the degree of involvement of the G protein subunit Gαq is not clear since animals with previously reported strong loss-of-function mutations remain responsive to light stimuli. We recovered a new allele of Gαq in Drosophila that abolishes light response in a conventional electroretinogram assay, and reduces sensitivity in whole-cell recordings of dissociated cells by at least five orders of magnitude. In addition, mutant eyes demonstrate a rapid rate of degeneration in the presence of light. Our new allele is likely the strongest hypomorph described to date. Interestingly, the mutant protein is produced in the eyes but carries a single amino acid change of a conserved hydrophobic residue that has been assigned to the interface of interaction between Gαq and its downstream effector, PLC. Our study has thus uncovered possibly the first point mutation that specifically affects this interaction in vivo.
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4
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Fan J, Zhang Y, Francis F, Cheng D, Sun J, Chen J. Orco mediates olfactory behaviors and winged morph differentiation induced by alarm pheromone in the grain aphid, Sitobion avenae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 64:16-24. [PMID: 26187252 DOI: 10.1016/j.ibmb.2015.07.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 05/27/2015] [Accepted: 07/06/2015] [Indexed: 06/04/2023]
Abstract
Olfaction is crucial for short distance host location and pheromone detection by insects. Complexes of olfactory receptors (ORs) are composed of odor-specific ORs and OR co-receptors (Orco). Orcos are widely co-expressed with odor-specific ORs and are conserved across insect taxa. A number of Orco orthologs have been studied to date, although none has been identified in cereal aphids. In this study, an Orco gene ortholog was cloned from the grain aphid, Sitobion avenae, and named "SaveOrco"; RNA interference (RNAi) reduced the expression of SaveOrco to 34.11% in aphids, resulting in weaker EAG (electroantennogram) responses to plant volatiles (Z-3-hexene-1-ol; methyl salicylate, MeSA) and aphid alarm pheromone (E-β-farnesene, EBF). Aphid wing differentiation induced by EBF was investigated in both RNAi treated and untreated aphids. EBF induced production of winged aphids in both pre-natal and post-natal periods in untreated aphids, but no such induction was observed in the RNAi-treated aphids. We conclude that SaveOrco is crucial for the aphid's response to pheromones and other volatiles, and is involved in wing differentiation triggered by EBF.
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Affiliation(s)
- Jia Fan
- State Key Laboratory of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China
| | - Yong Zhang
- State Key Laboratory of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China
| | - Frédéric Francis
- Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, B-5030, Belgium
| | - Dengfa Cheng
- State Key Laboratory of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China
| | - Jingrun Sun
- State Key Laboratory of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China
| | - Julian Chen
- State Key Laboratory of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China.
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Hull JJ, Wang M. Molecular Cloning and Characterization of G Alpha Proteins from the Western Tarnished Plant Bug, Lygus hesperus. INSECTS 2014; 6:54-76. [PMID: 26463065 PMCID: PMC4553527 DOI: 10.3390/insects6010054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/24/2014] [Indexed: 11/27/2022]
Abstract
The Gα subunits of heterotrimeric G proteins play critical roles in the activation of diverse signal transduction cascades. However, the role of these genes in chemosensation remains to be fully elucidated. To initiate a comprehensive survey of signal transduction genes, we used homology-based cloning methods and transcriptome data mining to identity Gα subunits in the western tarnished plant bug (Lygus hesperus Knight). Among the nine sequences identified were single variants of the Gαi, Gαo, Gαs, and Gα12 subfamilies and five alternative splice variants of the Gαq subfamily. Sequence alignment and phylogenetic analyses of the putative L. hesperus Gα subunits support initial classifications and are consistent with established evolutionary relationships. End-point PCR-based profiling of the transcripts indicated head specific expression for LhGαq4, and largely ubiquitous expression, albeit at varying levels, for the other LhGα transcripts. All subfamilies were amplified from L. hesperus chemosensory tissues, suggesting potential roles in olfaction and/or gustation. Immunohistochemical staining of cultured insect cells transiently expressing recombinant His-tagged LhGαi, LhGαs, and LhGαq1 revealed plasma membrane targeting, suggesting the respective sequences encode functional G protein subunits.
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Affiliation(s)
- J Joe Hull
- USDA-ARS Arid Land Agricultural Center, Maricopa, AZ 85138, USA.
| | - Meixian Wang
- USDA-ARS Arid Land Agricultural Center, Maricopa, AZ 85138, USA.
- Key Laboratory of Animal Virology of Ministry of Agriculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China.
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6
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Martin F, Boto T, Gomez-Diaz C, Alcorta E. Elements of olfactory reception in adult Drosophila melanogaster. Anat Rec (Hoboken) 2013; 296:1477-88. [PMID: 23904114 DOI: 10.1002/ar.22747] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 06/18/2013] [Indexed: 11/08/2022]
Abstract
The olfactory system of Drosophila has become an attractive and simple model to investigate olfaction because it follows the same organizational principles of vertebrates, and the results can be directly applied to other insects with economic and sanitary relevance. Here, we review the structural elements of the Drosophila olfactory reception organs at the level of the cells and molecules involved. This article is intended to reflect the structural basis underlying the functional variability of the detection of an olfactory universe composed of thousands of odors. At the genetic level, we further detail the genes and transcription factors (TF) that determine the structural variability. The fly's olfactory receptor organs are the third antennal segments and the maxillary palps, which are covered with sensory hairs called sensilla. These sensilla house the odorant receptor neurons (ORNs) that express one or few odorant receptors in a stereotyped pattern regulated by combinations of TF. Also, perireceptor events, such as odor molecules transport to their receptors, are carried out by odorant binding proteins. In addition, the rapid odorant inactivation to preclude saturation of the system occurs by biotransformation and detoxification enzymes. These additional events take place in the lymph that surrounds the ORNs. We include some data on ionotropic and metabotropic olfactory transduction, although this issue is still under debate in Drosophila.
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Affiliation(s)
- Fernando Martin
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Spain
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7
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Adachi R, Sasaki Y, Morita H, Komai M, Shirakawa H, Goto T, Furuyama A, Isono K. Behavioral analysis of Drosophila transformants expressing human taste receptor genes in the gustatory receptor neurons. J Neurogenet 2012; 26:198-205. [PMID: 22794107 DOI: 10.3109/01677063.2012.690254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Transgenic Drosophila expressing human T2R4 and T2R38 bitter-taste receptors or PKD2L1 sour-taste receptor in the fly gustatory receptor neurons and other tissues were prepared using conventional Gal4/UAS binary system. Molecular analysis showed that the transgene mRNAs are expressed according to the tissue specificity of the Gal4 drivers. Transformants expressing the transgene taste receptors in the fly taste neurons were then studied by a behavioral assay to analyze whether transgene chemoreceptors are functional and coupled to the cell response. Since wild-type flies show strong aversion against the T2R ligands as in mammals, the authors analyzed the transformants where the transgenes are expressed in the fly sugar receptor neurons so that they promote feeding ligand-dependently if they are functional and activate the neurons. Although the feeding preference varied considerably among different strains and individuals, statistical analysis using large numbers of transformants indicated that transformants expressing T2R4 showed a small but significant increase in the preference for denatonium and quinine, the T2R4 ligands, as compared to the control flies, whereas transformants expressing T2R38 did not. Similarly, transformants expressing T2R38 and PKD2L1 also showed a similar preference increase for T2R38-specific ligand phenylthiocarbamide (PTC) and a sour-taste ligand, citric acid, respectively. Taken together, the transformants expressing mammalian taste receptors showed a small but significant increase in the feeding preference that is taste receptor and also ligand dependent. Although future improvements are required to attain performance comparable to the endogenous robust response, Drosophila taste neurons may serve as a potential in vivo heterologous expression system for analyzing chemoreceptor function.
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Affiliation(s)
- Ryota Adachi
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyacho,Aoba-ku, Sendai, Japan
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8
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Hasan G. Intracellular signaling in neurons: unraveling specificity, compensatory mechanisms and essential gene function. Curr Opin Neurobiol 2012; 23:62-7. [PMID: 22878162 DOI: 10.1016/j.conb.2012.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 07/11/2012] [Accepted: 07/18/2012] [Indexed: 11/19/2022]
Abstract
Understanding how unique signaling outputs are generated in neurons using a limited set of intracellular signaling mechanisms has been a challenge. A combination of genetics and cell imaging, with tools developed to measure signaling outputs, has shown that the restricted presence of a signaling attenuator visibly alters the axonal range of the output and can be correlated with different behavioral outputs. Another question of interest is regarding the extent of genetic plasticity possible in the context of a single behavioral change. Recent molecular and genetic studies support the presence of parallel pathways that can compensate for the primary defect both at the level of physiology and behavior.
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Affiliation(s)
- Gaiti Hasan
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India.
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9
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Chemical Communication in Insects: The Peripheral Odour Coding System of Drosophila Melanogaster. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 739:59-77. [DOI: 10.1007/978-1-4614-1704-0_4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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10
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Deng Y, Zhang W, Farhat K, Oberland S, Gisselmann G, Neuhaus EM. The stimulatory Gα(s) protein is involved in olfactory signal transduction in Drosophila. PLoS One 2011; 6:e18605. [PMID: 21490930 PMCID: PMC3072409 DOI: 10.1371/journal.pone.0018605] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 03/11/2011] [Indexed: 11/19/2022] Open
Abstract
Seven-transmembrane receptors typically mediate olfactory signal transduction by coupling to G-proteins. Although insect odorant receptors have seven transmembrane domains like G-protein coupled receptors, they have an inverted membrane topology, constituting a key difference between the olfactory systems of insects and other animals. While heteromeric insect ORs form ligand-activated non-selective cation channels in recombinant expression systems, the evidence for an involvement of cyclic nucleotides and G-proteins in odor reception is inconsistent. We addressed this question in vivo by analyzing the role of G-proteins in olfactory signaling using electrophysiological recordings. We found that Gα(s) plays a crucial role for odorant induced signal transduction in OR83b expressing olfactory sensory neurons, but not in neurons expressing CO₂ responsive proteins GR21a/GR63a. Moreover, signaling of Drosophila ORs involved Gα(s) also in a heterologous expression system. In agreement with these observations was the finding that elevated levels of cAMP result in increased firing rates, demonstrating the existence of a cAMP dependent excitatory signaling pathway in the sensory neurons. Together, we provide evidence that Gα(s) plays a role in the OR mediated signaling cascade in Drosophila.
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Affiliation(s)
- Ying Deng
- Sino-France Joint Center for Drug Research and Screening, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, P. R. China
- Cell Physiology, Ruhr-University Bochum, Bochum, Germany
| | - Weiyi Zhang
- Cell Physiology, Ruhr-University Bochum, Bochum, Germany
- Bioduro (Beijing) Co. Ltd, Zhongguancun Life Science Park, Changping, Beijing, China
| | - Katja Farhat
- Cell Physiology, Ruhr-University Bochum, Bochum, Germany
- Department of Cardiovascular Physiology, Georg-August University, Göttingen, Germany
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11
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Kang GJ, Gong ZJ, Cheng JA, Zhu ZR, Mao CG. Cloning and expression analysis of a G-protein α subunit--Gαo in the rice water weevil Lissorhoptrus oryzophilus Kuschel. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2011; 76:43-54. [PMID: 21125564 DOI: 10.1002/arch.20403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The open reading frame (ORF) encoding a novel G protein α subunit, Lo Gα(o), was cloned from the parthenogenetic rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae). The Lo Gα(o) ORF encodes a protein of 354 amino acid residues. The deduced protein sequence shares high homology with Gα(o) from other species. The expression patterns of Lo Gα(o) in various adult tissues were indicated by real-time quantitative PCR and Western blot. The results showed that Lo Gα(o) mRNA was expressed at similar levels in tissues except relative high levels in the antennae of adult, and Lo Gα(o) protein of an apparent molecular mass of about 40 kDa was expressed in various tissues of the adult. Immunocytochemical localization showed that Lo Gα(o) was mainly expressed in the dendrites of the trichoid sensilla in the antenna of the weevil. The tissue and cellular localization of Lo Gα(o) suggests that Lo Gα(o) may take a part in signal transduction of olfactory/gustatory.
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Affiliation(s)
- Gui-Juan Kang
- State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, China
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12
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Abstract
Calling female moths attract their mates late at night with intermittent release of a species-specific sex-pheromone blend. Mean frequency of pheromone filaments encodes distance to the calling female. In their zig-zagging upwind search male moths encounter turbulent pheromone blend filaments at highly variable concentrations and frequencies. The male moth antennae are delicately designed to detect and distinguish even traces of these sex pheromones amongst the abundance of other odors. Its olfactory receptor neurons sense even single pheromone molecules and track intermittent pheromone filaments of highly variable frequencies up to about 30 Hz over a wide concentration range. In the hawkmoth Manduca sexta brief, weak pheromone stimuli as encountered during flight are detected via a metabotropic PLCβ-dependent signal transduction cascade which leads to transient changes in intracellular Ca2+ concentrations. Strong or long pheromone stimuli, which are possibly perceived in direct contact with the female, activate receptor-guanylyl cyclases causing long-term adaptation. In addition, depending on endogenous rhythms of the moth's physiological state, hormones such as the stress hormone octopamine modulate second messenger levels in sensory neurons. High octopamine levels during the activity phase maximize temporal resolution cAMP-dependently as a prerequisite to mate location. Thus, I suggest that sliding adjustment of odor response threshold and kinetics is based upon relative concentration ratios of intracellular Ca2+ and cyclic nucleotide levels which gate different ion channels synergistically. In addition, I propose a new hypothesis for the cyclic nucleotide-dependent ion channel formed by insect olfactory receptor/coreceptor complexes. Instead of being employed for an ionotropic mechanism of odor detection it is proposed to control subthreshold membrane potential oscillation of sensory neurons, as a basis for temporal encoding of odors.
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Affiliation(s)
- Monika Stengl
- FB 10, Biology, Animal Physiology, University of Kassel Kassel, Germany
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13
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Glatz R, Bailey-Hill K. Mimicking nature's noses: from receptor deorphaning to olfactory biosensing. Prog Neurobiol 2010; 93:270-96. [PMID: 21130137 DOI: 10.1016/j.pneurobio.2010.11.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 11/09/2010] [Accepted: 11/22/2010] [Indexed: 12/21/2022]
Abstract
The way in which organisms detect specific volatile compounds within their environment, and the associated neural processing which produces perception and subsequent behavioural responses, have been of interest to scientists for decades. Initially, most olfaction research was conducted using electrophysiological techniques on whole animals. However, the discovery of genes encoding the family of human olfactory receptors (ORs) paved the way for the development of a range of cellular assays, primarily used to deorphan ORs from mammals and insects. These assays have greatly advanced our knowledge of the molecular basis of olfaction, however, while there is currently good agreement on vertebrate and nematode olfactory signalling cascades, debate still surrounds the signalling mechanisms in insects. The inherent specificity and sensitivity of ORs makes them prime candidates as biological detectors of volatile ligands within biosensor devices, which have many potential applications. In the previous decade, researchers have investigated various technologies for transducing OR:ligand interactions into a readable format and thereby produce an olfactory biosensor (or bioelectronic nose) that maintains the discriminating power of the ORs in vivo. Here we review and compare the molecular mechanisms of olfaction in vertebrates and invertebrates, and also summarise the assay technologies utilising sub-tissue level sensing elements (cells and cell extracts), which have been applied to OR deorphanization and biosensor research. Although there are currently no commercial, "field-ready" olfactory biosensors of the kind discussed here, there have been several technological proof-of-concept studies suggesting that we will see their emergence within the next decade.
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Affiliation(s)
- Richard Glatz
- South Australian Research and Development Institute (SARDI), Entomology, GPO Box 397, Adelaide 5001, Australia.
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14
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Chatterjee A, Hardin PE. Time to taste: circadian clock function in the Drosophila gustatory system. Fly (Austin) 2010; 4:283-7. [PMID: 20798595 DOI: 10.4161/fly.4.4.13010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Circadian clocks keep time in the digestive, circulatory, reproductive, excretory and nervous systems even in absence of external cues. Central oscillators in the brain control locomotor activity of organisms ranging from fruit flies to man, but the functions of the clocks in peripheral nervous system are not well understood. The presence of autonomous peripheral oscillators in the major taste organ of Drosophila, the proboscis, prompted us to test whether gustatory responses are under control of the circadian clock. We find that synchronous rhythms in physiological and behavioral responses to attractive and aversive tastants are driven by oscillators in gustatory receptor neurons (GRNs); primary sensory neurons that carry taste information from the proboscis to the brain. During the middle of the night, high levels of G protein-coupled receptor kinase 2 (GPRK2) in the GRNs suppresses tastant-evoked responses. Flies with disrupted gustatory clocks are hyperphagic and hyperactive, recapitulating behaviors typically seen under the stress of starvation. Temporal plasticity in innate behaviors should offer adaptive advantages to flies. In this Extra View article we discuss how oscillators inside GRNs regulate responsiveness to tastants and influence feeding, metabolism and general activity.
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Affiliation(s)
- Abhishek Chatterjee
- Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX, USA
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15
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Kain P, Badsha F, Hussain SM, Nair A, Hasan G, Rodrigues V. Mutants in phospholipid signaling attenuate the behavioral response of adult Drosophila to trehalose. Chem Senses 2010; 35:663-73. [PMID: 20543015 DOI: 10.1093/chemse/bjq055] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In Drosophila melanogaster, gustatory receptor genes (Grs) encode putative G-protein-coupled receptors (GPCRs) that are expressed in gustatory receptor neurons (GRNs). One of the Gr genes, Gr5a, encodes a receptor for trehalose that is expressed in a subset of GRNs. Although a role for the G protein, Gsα, has been shown in Gr5a-expressing taste neurons, there is the residual responses to trehalose in Gsα mutants which could suggest additional transduction mechanisms. Expression and genetic analysis of the heterotrimeric G-protein subunit, Gq, shown here suggest involvement of this Gα subunit in trehalose perception in Drosophila. A green fluorescent protein reporter of Gq expression is detected in gustatory neurons in the labellum, tarsal segments, and wing margins. Animals heterozygous for dgq mutations and RNA interference-mediated knockdown of dgq showed reduced responses to trehalose in the proboscis extension reflex assay and feeding behavior assay. These defects were rescued by targeted expression of the wild-type dgqα transgene in the GRNs. These data together with observations from other mutants in phospholipid signaling provide insights into the mechanisms of taste transduction in Drosophila.
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Affiliation(s)
- Pinky Kain
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India
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16
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Abstract
A central question in insect chemoreception is whether signaling occurs via G-proteins. Two families of seven-transmembrane-domain chemoreceptors, the odor (Or) and gustatory receptor (Gr) families, have been identified in Drosophila (Clyne et al., 1999, 2000; Vosshall et al., 1999). Ors mediate odor responses, whereas two Grs, Gr21a and Gr63a, mediate CO2 response (Hallem et al., 2004; Jones et al., 2007; Kwon et al., 2007). Using single-sensillum recordings, we systematically investigate the role of Galpha proteins in vivo, initially with RNA interference constructs, competitive peptides, and constitutively active Galpha proteins. The results do not support a role for Galpha proteins in odor sensitivity. In parallel experiments, manipulations of Galpha(q), but not other Galpha proteins, affected CO2 response. Transient, conditional, and ectopic expression analyses consistently supported a role for Galpha(q) in the response of CO2-sensing neurons, but not odor-sensing neurons. Genetic mosaic analysis confirmed that odor responses are normal in the absence of Galpha(q). Ggamma30A is also required for normal CO2 response. The simplest interpretation of these results is that Galpha(q) and Ggamma30A play a role in the response of CO2-sensing neurons, but are not required for Or-mediated odor signaling.
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17
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Boto T, Gomez-Diaz C, Alcorta E. Expression analysis of the 3 G-protein subunits, Galpha, Gbeta, and Ggamma, in the olfactory receptor organs of adult Drosophila melanogaster. Chem Senses 2010; 35:183-93. [PMID: 20047983 DOI: 10.1093/chemse/bjp095] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In many species, olfactory transduction is triggered by odorant molecules that interact with olfactory receptors coupled to heterotrimeric G-proteins. The role of G-protein-linked transduction in the olfaction of Drosophila is currently under study. Here, we supply a thorough description of the expression in the olfactory receptor organs (antennae and maxillary palps) of all known Drosophila melanogaster genes that encode for G-proteins. Using RT-polymerase chain reaction, we analyzed 6 Galpha (G(s), G(i), G(q), G(o), G(f), and concertina), 3 Gbeta (G(beta5), G(beta13F), and G(beta76C)), and 2 Ggamma genes (G(gamma1) and G(gamma30A)). We found that all Galpha protein-encoding genes showed expression in both olfactory organs, but G(f) mRNA was not detected in palps. Moreover, all the Gbeta and Ggamma genes are expressed in antennae and palps, except for G(beta76C). To gain insight into the hypothesis of different G-protein subunits mediating differential signaling in olfactory receptor neurons (ORNs), we performed immunohistochemical studies to observe the expression of several Galpha and Gbeta proteins. We found that Gs, Gi, Gq, and G(beta13F) subunits displayed generalized expression in the antennal tissue, including ORNs support cells and glial cells. Finally, complete coexpression was found between Gi and Gq, which are mediators of the cyclic adenosine monophosphate and IP3 transduction cascades, respectively.
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Affiliation(s)
- Tamara Boto
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Julian Claveria s/n, 33006 Oviedo, Spain
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18
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ROS-GC subfamily membrane guanylate cyclase-linked transduction systems: taste, pineal gland and hippocampus. Mol Cell Biochem 2009; 334:199-206. [PMID: 19953306 DOI: 10.1007/s11010-009-0334-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022]
Abstract
In the continuous efforts to test the validity of the theme that the Ca(2+)-modulated ROS-GC subfamily system is a universal transduction component of the sensory and sensory-linked network of neurons, this article focuses on the presence and variant biochemical forms of this transduction system in the gustatory epithelium, the site of gustatory transduction; in the pineal, a light-sensitive gland; and in the hippocampus neurons, linked with the perception of all SENSES.
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19
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Cloning and eukaryotic expression of olfaction-related Gqα-protein gene in English grain aphid (Sitobion avenae). ACTA ACUST UNITED AC 2009. [DOI: 10.1017/s1479236209990180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractBased on conserved homologous amino-acid sequences of the Gq protein α subunit in arthropods, a pair of degenerate primers were designed to amplify the gene from the English grain aphid (Sitobion avenae), using reverse transcriptase polymerase chain reaction (RT-PCR) and (3′/5′)-rapid amplification of cDNA ends (3′/5′ RACE) techniques. A Gqα protein was obtained from the alate adult aphids. The open reading-frame was 1062 bp, encoding 352 amino-acid residues with a calculated molecular weight of 40.8 kDa. The cDNA sequence was deposited in GenBank with accession no. EF638906. The deduced amino-acid sequence of Gqα shared a high identity (≥82.17%) with reported Gqα from other insects and even vertebrates, and had the typical characteristics of Gqα protein. In order to explore the function of the Gqα gene, a eukaryotic expressional system (baculovirus expression vector system, BEVS) was constructed by TOPO and Gateway techniques. After the recombinant reaction occurring between pUC-Gqα and the Gateway-adapted baculovirus DNA from Autographa californica nuclear polyhedrosis virus (AcMNPV), the construct recombinant viruses containing V5-His6Gqα were transfected singly into the insect cell line of Tn-5B1-4. After collecting the infected cell, detection was conducted by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting. The result showed that the system comprising recombinant baculovirus and Tn could express Gqα protein successfully.
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20
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Pellegrino M, Nakagawa T. Smelling the difference: controversial ideas in insect olfaction. ACTA ACUST UNITED AC 2009; 212:1973-9. [PMID: 19525421 DOI: 10.1242/jeb.023036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In animals, the sense of smell is often used as a powerful way to attract potential mates, to find food and to explore the environment. Different animals evolved different systems to detect volatile odorants, tuned to the specific needs of each species. Vertebrates and nematodes have been used extensively as models to study the mechanisms of olfaction: the molecular players are olfactory receptors (ORs) expressed in olfactory sensory neurons (OSNs) where they bind to volatile chemicals, acting as the first relay of olfactory processing. These receptors belong to the G protein-coupled receptor (GPCR) superfamily; binding to odorants induces the production and amplification of second messengers, which lead to the depolarization of the neuron. The anatomical features of the insect olfactory circuit are similar to those of mammals, and until recently it was thought that this similarity extended to the ORs, which were originally annotated as GPCRs. Surprisingly, recent evidence shows that insect ORs can act like ligand-gated ion channels, either completely or partially bypassing the amplification steps connected to the activation of G proteins. Although the involvement of G proteins in insect olfactory signal transduction is still under question, this new discovery raises fascinating new questions regarding the function of the sense of smell in insects, its evolution and potential benefits compared with its mammalian counterpart.
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Affiliation(s)
- Maurizio Pellegrino
- Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, NY 10065, USA
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21
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Controversy and consensus: noncanonical signaling mechanisms in the insect olfactory system. Curr Opin Neurobiol 2009; 19:284-92. [PMID: 19660933 DOI: 10.1016/j.conb.2009.07.015] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 07/16/2009] [Accepted: 07/16/2009] [Indexed: 11/21/2022]
Abstract
There is broad consensus that olfactory signaling in vertebrates and the nematode C. elegans uses canonical G-protein-coupled receptor transduction pathways. In contrast, mechanisms of insect olfactory signal transduction remain deeply controversial. Genetic disruption of G proteins and chemosensory ion channels in mice and worms leads to profound impairment in olfaction, while similar mutations in the fly show more subtle phenotypes. The literature contains contradictory claims that insect olfaction uses cAMP, cGMP, or IP3 as second messengers; that insect odorant receptors couple to G(alpha)s or G(alpha)q pathways; and that insect odorant receptors are G-protein-coupled receptors or odor-gated ion channels. Here we consider all the evidence and offer a consensus model for a noncanonical mechanism of olfactory signal transduction in insects.
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22
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Ouyang Q, Sato H, Murata Y, Nakamura A, Ozaki M, Nakamura T. Contribution of the inositol 1,4,5-trisphosphate transduction cascade to the detection of "bitter" compounds in blowflies. Comp Biochem Physiol A Mol Integr Physiol 2009; 153:309-16. [PMID: 19275942 DOI: 10.1016/j.cbpa.2009.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 03/03/2009] [Accepted: 03/03/2009] [Indexed: 10/21/2022]
Abstract
Bitter taste detection is very important for many species including flies, because it prevents the ingestion of toxic food. Although it has been known that flies have specific bitter-sensitive taste cells in their contact chemosensilla, the mechanism by which those cells transduce the chemical signal into electrical activity has remained elusive. In this study, we first confirmed that type D4 and D5 tarsal chemosensilla of the blowfly Phormia regina responded well to bitter substances. Then, recording impulses from type D4 chemosensilla, we examined the possibility that a G-protein-coupled inositol 1,4,5-trisphosphate (IP(3))-dependent transduction cascade is of importance in the bitter-sensitive taste cells. We found that the response to bitter substances was depressed by specific inhibitors of G-protein, phospholipase C, or IP(3) receptor in the tarsal taste receptor cells. These results suggest that G-proteins mediate the IP(3) pathway in the transduction cascade in bitter-sensitive receptor cells.
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Affiliation(s)
- Qin Ouyang
- Department of Information Network Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
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23
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Smart R, Kiely A, Beale M, Vargas E, Carraher C, Kralicek AV, Christie DL, Chen C, Newcomb RD, Warr CG. Drosophila odorant receptors are novel seven transmembrane domain proteins that can signal independently of heterotrimeric G proteins. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2008; 38:770-780. [PMID: 18625400 DOI: 10.1016/j.ibmb.2008.05.002] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 05/12/2008] [Accepted: 05/12/2008] [Indexed: 05/26/2023]
Abstract
Olfaction in Drosophila is mediated by a large family of membrane-bound odorant receptor proteins (Ors). In heterologous cells, we investigated whether the structural features and signalling mechanisms of ligand-binding Drosophila Ors are consistent with them being G protein-coupled receptors (GPCRs). The detailed membrane topology of Or22a was determined by inserting epitope tags into the termini and predicted loop regions. Immunocytochemistry experiments in Drosophila S2 cells imply that Or22a has seven transmembrane domains but that its membrane topology is opposite to that of GPCRs, with a cytoplasmic N-terminus and extracellular C-terminus. To investigate Or signalling mechanisms, we expressed Or43b in Sf9 and HEK293 cells, and show that inhibitors of heterotrimeric G proteins (GDP-beta-S), adenylate cyclase (SQ22536), guanylyl cyclase (ODQ), cyclic nucleotide phosphodiesterases (IBMX) and phospholipase C (U73122) have negligible impact on Or43b responses. Whole cell patching of Or43b/Or83b-transfected HEK293 cells revealed the opening of plasma membrane cation channels on addition of ligand. The response was blocked by lanthanum and by 2-APB, but not by Ruthenium red or SKF96365. Based on these data, we conclude that Drosophila Ors comprise a novel family of seven transmembrane receptors that in HEK293 cells signal by opening cation channels, through a mechanism that is largely independent of G proteins.
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Affiliation(s)
- Renee Smart
- School of Biological Sciences, Monash University, Melbourne, Vic. 3800, Australia
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24
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Tsie MS, Rawson PD, Lindsay SM. Immunolocalization of a Galphaq protein to the chemosensory organs of Dipolydora quadrilobata (polychaeta: spionidae). Cell Tissue Res 2008; 333:469-80. [PMID: 18604560 DOI: 10.1007/s00441-008-0660-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 06/03/2008] [Indexed: 11/30/2022]
Abstract
Chemoreception in marine invertebrates mediates a variety of ecologically important behaviors including defense, reproduction, larval settlement and recruitment, and feeding. The sensory pathways that regulate deposit-feeding activity by polychaetes living in sedimentary habitats are of particular interest because such feeding has profound effects on the physical and chemical properties of the habitat. Nevertheless, little is known concerning the molecular mechanisms of chemical signal transduction associated with deposit feeding and other behaviors in polychaetes. Chemosensory-based feeding behaviors are typically regulated by G-protein-coupled signal transduction pathways. However, the presence and role of such pathways have not been demonstrated in marine polychaetes. Methodologies involving degenerate primer-based reverse transcription with the polymerase chain reaction and rapid amplification of cDNA ends were used to identify and characterize a Galphaq subunit expressed in the feeding palps of the spionid polychaete Dipolydora quadrilobata. The D. quadrilobata Galphaq protein had high sequence similarity with previously reported Galphaq subunits from both invertebrate and vertebrate taxa. Immunhistochemistry and immunocytochemistry were used with confocal laser scanning microscopy and transmission electron microscopy to visualize the distribution of a Galphaq antibody in whole worms and in cilia of the feeding palps. Galphaq immunoreactivity was concentrated in the nuchal organs, food-groove cilia, and lateral/abfrontal cilia of the feeding palps. Because these structures are known to be involved in chemoreception, we propose that Galphaq isolated from D. quadrilobata is a key component of chemosensory signal transduction pathways in this species.
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Affiliation(s)
- Marlene S Tsie
- School of Marine Sciences, University of Maine, Orono, ME 04469-5751, USA
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25
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Kain P, Chakraborty TS, Sundaram S, Siddiqi O, Rodrigues V, Hasan G. Reduced odor responses from antennal neurons of G(q)alpha, phospholipase Cbeta, and rdgA mutants in Drosophila support a role for a phospholipid intermediate in insect olfactory transduction. J Neurosci 2008; 28:4745-55. [PMID: 18448651 PMCID: PMC3844817 DOI: 10.1523/jneurosci.5306-07.2008] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 04/02/2008] [Accepted: 04/02/2008] [Indexed: 11/21/2022] Open
Abstract
Mechanisms by which G-protein-coupled odorant receptors transduce information in insects still need elucidation. We show that mutations in the Drosophila gene for G(q)alpha (dgq) significantly reduce both the amplitude of the field potentials recorded from the whole antenna in responses to odorants as well as the frequency of evoked responses of individual sensory neurons. This requirement for G(q)alpha is for adult function and not during antennal development. Conversely, brief expression of a dominant-active form of G(q)alpha in adults leads to enhanced odor responses. To understand signaling downstream of G(q)alpha in olfactory sensory neurons, genetic interactions of dgq were tested with mutants in genes known to affect phospholipid signaling. dgq mutant phenotypes were further enhanced by mutants in a PLCbeta (phospholipase Cbeta) gene, plc21C. Interestingly although, the olfactory phenotype of mutant alleles of diacylglycerol kinase (rdgA) was rescued by dgq mutant alleles. Our results suggest that G(q)alpha-mediated olfactory transduction in Drosophila requires a phospholipid second messenger the levels of which are regulated by a cycle of phosphatidylinositol 1,4-bisphosphate breakdown and regeneration.
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Affiliation(s)
- Pinky Kain
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India, and
| | - Tuhin Subra Chakraborty
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India, and
| | - Susinder Sundaram
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Obaid Siddiqi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India, and
| | - Veronica Rodrigues
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India, and
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India, and
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26
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QIAO Q, LI HC, YUAN GH, GUO XR, LUO MH. Gene Cloning and Expression Analysis of G Protein αq Subunit from Helicoverpa assulta (Guenée). ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1671-2927(08)60038-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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27
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Hull JJ, Kajigaya R, Imai K, Matsumoto S. The Bombyx mori sex pheromone biosynthetic pathway is not mediated by cAMP. JOURNAL OF INSECT PHYSIOLOGY 2007; 53:782-93. [PMID: 17449058 DOI: 10.1016/j.jinsphys.2007.02.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2006] [Revised: 02/17/2007] [Accepted: 02/19/2007] [Indexed: 05/15/2023]
Abstract
In most moths, sex pheromone production is regulated by pheromone biosynthesis-activating neuropeptide (PBAN). How the extracellular PBAN signal is turned into a biological response has been the focus of numerous studies. In the classical scheme of signal transduction, activated G proteins relay the extracellular signal to downstream effector molecules such as calcium channels and adenylyl cyclase. The role of calcium in PBAN signaling has been clearly demonstrated, but the possible involvement of cAMP is not as straightforward. While cAMP has been shown to be necessary for PBAN signaling in most heliothine species, there has been no definitive demonstration of its role in Bombyx mori. To address this question, we used degenerate RT-PCR to clone two Gs subunits, designated P50Gs1 and P50Gs2, from B. mori pheromone gland (PG) cDNAs. The two Gs proteins were expressed in all tissues examined and were not up-regulated in accordance with adult eclosion. Even though two bands corresponding to the approximate molecular weights of P50Gs1 and P50Gs2 were detected in PG homogenates, the Gs antagonist, NF449, had no effect on sex pheromone production. Furthermore, no changes in the intracellular cAMP levels were detected following PBAN stimulation.
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Affiliation(s)
- J Joe Hull
- Molecular Entomology Laboratory, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
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28
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Ebbs ML, Amrein H. Taste and pheromone perception in the fruit fly Drosophila melanogaster. Pflugers Arch 2007; 454:735-47. [PMID: 17473934 DOI: 10.1007/s00424-007-0246-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 01/04/2007] [Accepted: 01/15/2007] [Indexed: 01/25/2023]
Abstract
Taste is an essential sense for detection of nutrient-rich food and avoidance of toxic substances. The Drosophila melanogaster gustatory system provides an excellent model to study taste perception and taste-elicited behaviors. "The fly" is unique in the animal kingdom with regard to available experimental tools, which include a wide repertoire of molecular-genetic analyses (i.e., efficient production of transgenics and gene knockouts), elegant behavioral assays, and the possibility to conduct electrophysiological investigations. In addition, fruit flies, like humans, recognize sugars as a food source, but avoid bitter tasting substances that are often toxic to insects and mammals alike. This paper will present recent research progress in the field of taste and contact pheromone perception in the fruit fly. First, we shall describe the anatomical properties of the Drosophila gustatory system and survey the family of taste receptors to provide an appropriate background. We shall then review taste and pheromone perception mainly from a molecular genetic perspective that includes behavioral, electrophysiological and imaging analyses of wild type flies and flies with genetically manipulated taste cells. Finally, we shall provide an outlook of taste research in this elegant model system for the next few years.
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Affiliation(s)
- Michelle L Ebbs
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 252 CARL Bldg./Research Drive, Durham, NC 27710, USA
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29
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Smith DP. Odor and pheromone detection in Drosophila melanogaster. Pflugers Arch 2007; 454:749-58. [PMID: 17205355 DOI: 10.1007/s00424-006-0190-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 11/08/2006] [Indexed: 11/28/2022]
Abstract
Drosophila melanogaster has proven to be a useful model system to probe the mechanisms underlying the detection, discrimination, and perception of volatile odorants. The relatively small receptor repertoire of 62 odorant receptors makes the goal of understanding odor responses from the total receptor repertoire approachable in this system, and recent work has been directed toward this goal. In addition, new work not only sheds light but also raises more questions about the initial steps in odor perception in this system. Odorant receptor genes in Drosophila are predicted to encode seven transmembrane receptors, but surprising data suggest that these receptors may be inverted in the plasma membrane compared to classical G-protein coupled receptors. Finally, although some Drosophila odorant receptors are activated directly by odorant molecules, detection of a volatile pheromone, 11-cis vaccenyl acetate requires an extracellular adapter protein called LUSH for activation of pheromone sensitive neurons. Because pheromones are used by insects to trigger mating and other behaviors, these insights may herald new approaches to control behavior in pathogenic and agricultural pest insects.
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MESH Headings
- Acetates
- Animals
- Discrimination, Psychological/physiology
- Drosophila Proteins/agonists
- Drosophila Proteins/genetics
- Drosophila Proteins/metabolism
- Drosophila melanogaster/anatomy & histology
- Drosophila melanogaster/genetics
- Drosophila melanogaster/physiology
- Female
- GTP-Binding Proteins/metabolism
- Genes, Insect/physiology
- Humans
- Male
- Nerve Net
- Odorants
- Oleic Acids
- Olfactory Receptor Neurons/cytology
- Olfactory Receptor Neurons/physiology
- Pheromones/physiology
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Odorant/agonists
- Receptors, Odorant/genetics
- Receptors, Odorant/metabolism
- Receptors, Pheromone/agonists
- Receptors, Pheromone/genetics
- Receptors, Pheromone/metabolism
- Sense Organs/anatomy & histology
- Sense Organs/metabolism
- Sexual Behavior, Animal/physiology
- Signal Transduction/drug effects
- Signal Transduction/genetics
- Smell/physiology
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Affiliation(s)
- Dean P Smith
- Department of Pharmacology and Center for Basic Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9111, USA.
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30
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Rützler M, Lu T, Zwiebel LJ. Galpha encoding gene family of the malaria vector mosquito Anopheles gambiae: expression analysis and immunolocalization of AGalphaq and AGalphao in female antennae. J Comp Neurol 2006; 499:533-45. [PMID: 17029251 PMCID: PMC3113460 DOI: 10.1002/cne.21083] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
To initiate a comprehensive investigation of chemosensory signal transduction downstream of odorant receptors, we identified and characterized the complete set of genes that encode G-protein alpha subunits in the genome of the malaria vector mosquito An. gambiae. Data are provided on the tissue-specific expression patterns of 10 corresponding aga-transcripts in adult mosquitoes and pre-imago developmental stages. Specific immunoreactivity in chemosensory hairs of female antennae provides evidence in support of the participation of a subset of AGalphaq isoforms in olfactory signal transduction in this mosquito. In contrast, AGalphao is localized along the flagellar axon bundle but is absent from chemosensory sensilla, which suggests that this G-protein alpha subunit does not participate in olfactory signal transduction.
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Affiliation(s)
| | | | - Laurence J. Zwiebel
- Correspondence to: L.J. Zwiebel, Department of Biological Sciences, Program in Developmental Biology, Centers for Molecular Neuroscience and Chemical Biology, Institute for Global Health, VU Station B, Box 35–1634, Vanderbilt University, Nashville, TN 37235.
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31
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Ueno K, Kohatsu S, Clay C, Forte M, Isono K, Kidokoro Y. Gsalpha is involved in sugar perception in Drosophila melanogaster. J Neurosci 2006; 26:6143-52. [PMID: 16763022 PMCID: PMC6675175 DOI: 10.1523/jneurosci.0857-06.2006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In Drosophila melanogaster, gustatory receptor genes (Grs) encode G-protein-coupled receptors (GPCRs) in gustatory receptor neurons (GRNs) and some olfactory receptor neurons. One of the Gr genes, Gr5a, encodes a sugar receptor that is expressed in a subset of GRNs and has been most extensively studied both molecularly and physiologically, but the G-protein alpha subunit (Galpha) that is coupled to this sugar receptor remains unknown. Here, we propose that Gs is the Galpha that is responsible for Gr5a-mediated sugar-taste transduction, based on the following findings: First, immunoreactivities against Gs were detected in a subset of GRNs including all Gr5a-expressing neurons. Second, trehalose-intake is reduced in flies heterozygous for null mutations in DGsalpha, a homolog of mammalian Gs, and trehalose-induced electrical activities in sugar-sensitive GRNs were depressed in those flies. Furthermore, expression of wild-type DGsalpha in sugar-sensitive GRNs in heterozygotic DGsalpha mutant flies rescued those impairments. Third, expression of double-stranded RNA for DGsalpha in sugar-sensitive GRNs depressed both behavioral and electrophysiological responses to trehalose. Together, these findings indicate that DGsalpha is involved in trehalose perception. We suggest that sugar-taste signals are processed through the Gsalpha-mediating signal transduction pathway in sugar-sensitive GRNs in Drosophila.
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Affiliation(s)
- Kohei Ueno
- Department of Behavioral Sciences, Graduate School of Medicine, Gunma University, Maebashi 371-8511, Japan.
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32
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Benton R, Sachse S, Michnick SW, Vosshall LB. Atypical membrane topology and heteromeric function of Drosophila odorant receptors in vivo. PLoS Biol 2006; 4:e20. [PMID: 16402857 PMCID: PMC1334387 DOI: 10.1371/journal.pbio.0040020] [Citation(s) in RCA: 693] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Accepted: 11/14/2005] [Indexed: 11/18/2022] Open
Abstract
Drosophila olfactory sensory neurons (OSNs) each express two odorant receptors (ORs): a divergent member of the OR family and the highly conserved, broadly expressed receptor OR83b. OR83b is essential for olfaction in vivo and enhances OR function in vitro, but the molecular mechanism by which it acts is unknown. Here we demonstrate that OR83b heterodimerizes with conventional ORs early in the endomembrane system in OSNs, couples these complexes to the conserved ciliary trafficking pathway, and is essential to maintain the OR/OR83b complex within the sensory cilia, where odor signal transduction occurs. The OR/OR83b complex is necessary and sufficient to promote functional reconstitution of odor-evoked signaling in sensory neurons that normally respond only to carbon dioxide. Unexpectedly, unlike all known vertebrate and nematode chemosensory receptors, we find that Drosophila ORs and OR83b adopt a novel membrane topology with their N-termini and the most conserved loops in the cytoplasm. These loops mediate direct association of ORs with OR83b. Our results reveal that OR83b is a universal and integral part of the functional OR in Drosophila. This atypical heteromeric and topological design appears to be an insect-specific solution for odor recognition, making the OR/OR83b complex an attractive target for the development of highly selective insect repellents to disrupt olfactory-mediated host-seeking behaviors of insect disease vectors. This study reveals a novel membrane topology for olfactory receptors in Drosophila and details the molecular mechanisms of receptor localization at the sensory cilia.
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Affiliation(s)
- Richard Benton
- 1Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, New York, United States of America
| | - Silke Sachse
- 1Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, New York, United States of America
| | - Stephen W Michnick
- 2Département de Biochimie, Université de Montréal, Montréal, Québec, Canada
| | - Leslie B Vosshall
- 1Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, New York, United States of America
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Ishimoto H, Takahashi K, Ueda R, Tanimura T. G-protein gamma subunit 1 is required for sugar reception in Drosophila. EMBO J 2005; 24:3259-65. [PMID: 16121192 PMCID: PMC1224686 DOI: 10.1038/sj.emboj.7600796] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Accepted: 08/03/2005] [Indexed: 11/09/2022] Open
Abstract
Though G-proteins have been implicated in the primary step of taste signal transduction, no direct demonstration has been done in insects. We show here that a G-protein gamma subunit, Ggamma1, is required for the signal transduction of sugar taste reception in Drosophila. The Ggamma1 gene is expressed mainly in one of the gustatory receptor neurons. Behavioral responses of the flies to sucrose were reduced by the targeted suppression of neural functions of Ggamma1-expressing cells using neural modulator genes such as the modified Shaker K+ channel (EKO), the tetanus toxin light chain or the shibire (shi(ts1)) gene. RNA interference targeting to the Ggamma1 gene reduced the amount of Ggamma1 mRNA and suppressed electrophysiological response of the sugar receptor neuron. We also demonstrated that responses to sugars were lowered in Ggamma1 null mutant, Ggamma1(N159). These results are consistent with the hypothesis that Ggamma1 participates in the signal transduction of sugar taste reception.
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Affiliation(s)
- Hiroshi Ishimoto
- Department of Biology, Graduate School of Sciences, Kyushu University, Ropponmatsu, Fukuoka, Japan
| | - Kuniaki Takahashi
- Genetic Strains Research Center, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Ryu Ueda
- Genetic Strains Research Center, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Teiichi Tanimura
- Department of Biology, Graduate School of Sciences, Kyushu University, Ropponmatsu, Fukuoka, Japan
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Abstract
The sense of taste is essential for the survival of virtually all animals. Considered a 'primitive sense' and present in the form of chemotaxis in many bacteria, taste is also a sense of sophistication in humans. Regardless, taste behavior is a crucial activity for the world's most abundant (insects) and most successful (mammals) inhabitants, providing a means of discrimination between nutrient-rich substrates, such as sugars and amino acids, from harmful, mostly bitter-tasting chemicals present in many plants. In this review, we present an update on progress in understanding taste perception in the model fruit fly Drosophila melanogaster. An introduction to the fly's taste system will be presented first, followed by a description of relevant behavioral assays developed to quantify taste perception at the organismal level and a short overview of electrophysiological studies performed on taste cells. The focal point will be the recent molecular-genetic investigations of the gustatory receptor (Gr) genes, which is complemented by a comparison between Drosophila and mammalian taste perception and transduction. Finally, we provide a perspective on the future of Drosophila taste research, including three specific proposals that seem uniquely applicable to this exquisite model system and cannot, at least currently, be pursued elsewhere.
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Affiliation(s)
- Hubert Amrein
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Miura N, Atsumi S, Tabunoki H, Sato R. Expression and localization of three G protein alpha subunits, Go, Gq, and Gs, in adult antennae of the silkmoth (Bombyx mori). J Comp Neurol 2005; 485:143-52. [PMID: 15776452 DOI: 10.1002/cne.20488] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In insect olfactory receptor neurons, rapid and transient increases in inositol triphosphate (IP3) and Ca2+ are detected upon stimulation with pheromone or nonpheromonal odorants. This suggests that heterotrimeric guanine nucleotide binding proteins (G proteins) may transduce some odorant responses in insects. We obtained cDNA clones encoding three classes of G protein alpha subunits, Bm Go, Bm Gq, and Bm Gs, from the antennae of the adult male silkmoth (Bombyx mori). RT-PCR experiments showed that the mRNA of these G protein alpha subunits was also present in the various tissues of adult and larval insects. We used immunocytochemistry to localize these G protein alpha subunits in adult male and female antennae. In the adult male antennae, anti-Go antiserum stained the nerve bundles. In contrast, anti-Gq and anti-Gs antisera stained the inner and outer dendritic segments of the putative olfactory receptor neuron. The localizations of Bm Go, Bm Gq, and Bm Gs in the female antennae were the same as in the male antennae. The localizations of Bm Gq and Bm Gs suggest that each subunit mediates a subset of the odorant response.
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Affiliation(s)
- Nami Miura
- Laboratory of Molecular Mechanism of Bio-Interaction, Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
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Duda T, Sharma RK. S100B-modulated Ca2+-dependent ROS-GC1 transduction machinery in the gustatory epithelium: a new mechanism in gustatory transduction. FEBS Lett 2005; 577:393-8. [PMID: 15556616 DOI: 10.1016/j.febslet.2004.09.089] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 09/07/2004] [Accepted: 09/09/2004] [Indexed: 10/26/2022]
Abstract
Gustatory transduction is a biochemical process by which the gustatory signal generates the electric signal. The microvilli of the taste cells in the gustatory epithelium are the sites of gustatory transduction. This study documents the biochemical, molecular, and functional identity of the Ca2+-modulated membrane guanylate cyclase transduction machinery in the bovine gustatory epithelium. The machinery is a two-component system: the Ca2+-sensor protein, S100B; and the transducer, ROS-GC1. S100B senses increments in free Ca2+, undergoes conformational change, binds to the domain amino acids (aa) Gly962-Asn981 and via the transduction domain aa Ile1030-Gln1041 activates ROS-GC1, generating the second messenger, cyclic GMP. In a recent study, operational presence of this machinery has been demonstrated in the photoreceptor bipolar synapse [Duda et al., EMBO J. 21 (2002) 2547]. Thus, the machinery has a broader role in sensory perceptions, vision in the retinal neurons and gustation in the tongue. The entry of the ROS-GC transduction machinery defines the beginning of a new paradigm of Ca2+ signaling in the tongue.
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Affiliation(s)
- Teresa Duda
- The Unit of Regulatory and Molecular Biology, Department of Cell Biology, SOM & NJMS, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA.
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37
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Hollins B, Hardin D, Gimelbrant AA, McClintock TS. Olfactory-enriched transcripts are cell-specific markers in the lobster olfactory organ. J Comp Neurol 2003; 455:125-38. [PMID: 12455001 DOI: 10.1002/cne.10489] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Genes expressed specifically in a tissue are often involved in the defining functions of that tissue. We used representational difference analysis of cDNA to amplify 20 cDNA fragments representing transcripts that were more abundant in the lobster olfactory organ than in brain, eye/eyestalk, dactyl, pereiopod, or second antenna. We then independently confirmed that the transcripts represented by these clones were enriched in the olfactory organ. The 20 cDNA fragments represent between 6 and 15 different genes. Six of the cDNAs contained sequences highly similar to known gene families. We performed in situ hybridization with these six and found that all were expressed in subsets of cells associated with the aesthetasc sensilla in the olfactory organ. Clones OET-07, an ionotropic receptor, and OET-10, an alpha tubulin, were specific to the olfactory receptor neurons. OET-02, a monooxygenase, was expressed only in the outer auxiliary cells. OET-03, a serine protease, was specific to the collar cells. OET-11, an alpha(2) macroglobulin, was expressed by the receptor neurons and the collar cells. OET-17, a calcyphosine, was expressed in the receptor neurons, inner auxiliary cells, and collar cells. The identities and expression patterns of these six transcripts predict involvement in both known and novel properties of the lobster olfactory organ.
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Affiliation(s)
- Bettye Hollins
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536-0298, USA
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38
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Abstract
A majority of neurons that form the ventral nerve cord send out long axons that cross the midline through anterior or posterior commissures. A smaller fraction extend longitudinally and never cross the midline. The decision to cross the midline is governed by a balance of attractive and repulsive signals. We have explored the role of a G-protein, Galphaq, in altering this balance in Drosophila. A splice variant of Galphaq, dgqalpha3, is expressed in early axonal growth cones, which go to form the commissures in the Drosophila embryonic CNS. Misexpression of a gain-of-function transgene of dgqalpha3 (AcGq3) leads to ectopic midline crossing. Analysis of the AcGq3 phenotype in roundabout and frazzled mutants shows that AcGq3 function is antagonistic to Robo signaling and requires Frazzled to promote ectopic midline crossing. Our results show for the first time that a heterotrimeric G-protein can affect the balance of attractive versus repulsive cues in the growth cone and that it can function as a component of signaling pathways that regulate axonal pathfinding.
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Jacquin-Joly E, François MC, Burnet M, Lucas P, Bourrat F, Maida R. Expression pattern in the antennae of a newly isolated lepidopteran Gq protein alpha subunit cDNA. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:2133-42. [PMID: 11985591 DOI: 10.1046/j.1432-1033.2002.02863.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
From the antennae of the moth Mamestra brassicae, we have identified a lepidopteran G protein alpha subunit belonging to the Gq family, through immunological detection in crude antennal extract and antennal primary cell cultures, followed by molecular cloning. The complete cDNA sequence (1540 bp) contains an open reading frame encoding a protein of 353 amino acids. This deduced sequence possesses all of the characteristics of the Gq family and shares a very high degree of amino-acid sequence identity with vertebrate (80% with mouse or human Gqalpha) and invertebrate subunits (varying between 60 and 87% for Gqalpha from organisms as diverse as sponge and Drosophila). The expression pattern of the Gq subunit in adult antennae was associated with the olfactory sensilla suggesting a specific role in olfaction. These data provide molecular evidence for a component of the phosphoinositide signaling pathway in moth antennae: this G protein alpha subunit may be involved in the olfaction transduction process through interaction with G-protein-coupled receptors, stimulating the phospholipase C mediated second messenger pathway.
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Affiliation(s)
- Emmanuelle Jacquin-Joly
- INRA, Unité de Phytopharmacie et Médiateurs Chimiques, Route de Saint-Cyr, Versailles cedex, France.
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Koganezawa M, Shimada I. Inositol 1,4,5-trisphosphate transduction cascade in taste reception of the fleshfly, Boettcherisca peregrina. JOURNAL OF NEUROBIOLOGY 2002; 51:66-83. [PMID: 11920729 DOI: 10.1002/neu.10047] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The role of an inositol 1,4,5-trisphosphate (IP3)-mediated transduction cascade in the response of taste receptor cells of the fleshfly Boettcherisca peregrina was investigated by using the following reagents: neomycin (an inhibitor of IP3 production), U73122 (an inhibitor of phospholipase C), adenophostin A (an agonist of the IP3-gated channel), IP3, ruthenium red (a blocker of the IP3-gated channel), and 2-aminoethoxydiphenylborate (2-APB; an antagonist of the IP3-gated channel). For introduction into the receptor cell, the reagents were mixed with a detergent, deoxycholate (DOC). After treatment with neomycin + DOC or U73122 + DOC, the response of the sugar receptor cell to sugars was depressed compared with responses after treatment with DOC alone. During the treatment of adenophostin A + DOC, the response of the sugar receptor cell was elicited. After treatment with IP3 + DOC, the response of the sugar receptor cell to sugars and to amino acids was apparently enhanced. When taste stimuli were administered in the presence of ruthenium red or 2-APB, the response of the sugar receptor cell to glucose were inhibited. The expression of genes for substances involved in the IP3 transduction cascade, such as G protein alpha subunit (dGqalpha), phospholipase C (norpA), and IP3 receptor (itpr), were examined in the taste receptor cell of the fruitfly Drosophila melanogaster by using the pox-neuro70 mutant (poxn70), which lacks taste receptor cells. The expressed levels of dGqalpha and itpr in the tarsus of poxn70 mutant flies were reduced compared with those of wild-type flies. These results suggest that the IP3 transduction cascade is involved in the response of the sugar receptor cell of the fly.
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Affiliation(s)
- Masayuki Koganezawa
- Biological Institute, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
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41
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Abstract
Drosophila melanogaster has been a premier genetic model system for nearly 100 years, yet lacks a simple method to disrupt gene expression. Here, we show genomic cDNA fusions predicted to form double-stranded RNA (dsRNA) following splicing, effectively silencing expression of target genes in adult transgenic animals. We targeted three Drosophila genes: lush, white, and dGq(alpha). In each case, target gene expression is dramatically reduced, and the white RNAi phenotype is indistinguishable from a deletion mutant. This technique efficiently targets genes expressed in neurons, a tissue refractory to RNAi in C. elegans. These results demonstrate a simple strategy to knock out gene function in specific cells in living adult Drosophila that can be applied to define the biological function of hundreds of orphan genes and open reading frames.
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Affiliation(s)
- Savitha Kalidas
- Department of Pharmacology and Center for Basic Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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42
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Galindo K, Smith DP. A large family of divergent Drosophila odorant-binding proteins expressed in gustatory and olfactory sensilla. Genetics 2001; 159:1059-72. [PMID: 11729153 PMCID: PMC1461854 DOI: 10.1093/genetics/159.3.1059] [Citation(s) in RCA: 213] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We identified a large family of putative odorant-binding protein (OBP) genes in the genome of Drosophila melanogaster. Some of these genes are present in large clusters in the genome. Most members are expressed in various taste organs, including gustatory sensilla in the labellum, the pharyngeal labral sense organ, dorsal and ventral cibarial organs, as well as taste bristles located on the wings and tarsi. Some of the gustatory OBPs are expressed exclusively in taste organs, but most are expressed in both olfactory and gustatory sensilla. Multiple binding proteins can be coexpressed in the same gustatory sensillum. Cells in the tarsi that express OBPs are required for normal chemosensation mediated through the leg, as ablation of these cells dramatically reduces the sensitivity of the proboscis extension reflex to sucrose. Finally, we show that OBP genes expressed in the pharyngeal taste sensilla are still expressed in the poxneuro genetic background while OBPs expressed in the labellum are not. These findings support a broad role for members of the OBP family in gustation and olfaction and suggest that poxneuro is required for cell fate determination of labellar but not pharyngeal taste organs.
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Affiliation(s)
- K Galindo
- Department of Pharmacology and Center for Basic Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9111, USA
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43
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Shiraiwa T, Nitasaka E, Yamazaki T. Geko, a novel gene involved in olfaction in Drosophila melanogaster. J Neurogenet 2000; 14:145-64. [PMID: 10992166 DOI: 10.3109/01677060009083480] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To characterize genes involved in olfactory responses to chemical attractants, we screened 3000 P-element-tagged lines for their attraction to ethanol. Ten lines showed reduced levels of response, and revertants of these lines were obtained by excising the inserted P-element. The olfactory response of one line reverted to wild-type behavior compared to the original mutant line. The gene affected by this P-lacW insertion was named geko (gk). A 1.3-kb transcript was found to emanate from close to the P-insertion site, and the 5' upstream region was interrupted by the P-element. The amount of mRNA of gk gene in the P-lacW inserted line was about half that of the control strain. The response to ethanol of the gk(1) mutant was restored by transforming the genomic region containing this transcription unit. lacZ expression (stemming from this reporter-gene's presence in the transposon) was observed in the antenna and the antennal-maxillary complex (the olfactory organ of adults and larvae, respectively). gk mRNA was detected at the antenna and from other parts of the body. The deduced gk product showed no overall similarity to any reported amino-acid sequences.
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Affiliation(s)
- T Shiraiwa
- Department of Molecular Biology, Graduate School of Medical Science; Kyushu University, Fukuoka 812-8581, Japan.
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44
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Abstract
The fruit fly, Drosophila melanogaster, is equipped with a sophisticated olfactory sensory system that permits it to recognize and discriminate hundreds of discrete odorants. The perception of these odorants is essential for the animal to identify relevant food sources and suitable sites for egg-laying. Advances in the last year have begun to define the molecular basis of this insect's discriminatory power. The identification of a large multi-gene family of candidate Drosophila odorant receptors suggests that, as in other animals, a multitude of distinct odorants is recognized by a diversity of ligand-binding receptors. How olfactory signals are transduced and interpreted by the brain remains an important question for future analysis. The availability of genetic tools and a complete genome sequence makes Drosophila a particularly attractive organism for studying the molecular basis of olfaction.
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Affiliation(s)
- L B Vosshall
- Center for Neurobiology and Behavior, Columbia University, New York, NY 10032, USA.
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45
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Robertson HM, Martos R, Sears CR, Todres EZ, Walden KK, Nardi JB. Diversity of odourant binding proteins revealed by an expressed sequence tag project on male Manduca sexta moth antennae. INSECT MOLECULAR BIOLOGY 1999; 8:501-518. [PMID: 10620045 DOI: 10.1046/j.1365-2583.1999.00146.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A small expressed sequence tag (EST) project generating 506 ESTs from 375 cDNAs was undertaken on the antennae of male Manduca sexta moths in an effort to discover olfactory receptor proteins. We encountered several clones that encode apparent transmembrane proteins; however, none is a clear candidate for an olfactory receptor. Instead we found a greater diversity of odourant binding proteins (OBPs) than previously known in moth antennae, raising the number known for M. sexta from three to seven. Together with evidence of seventeen members of the family from the Drosophila melanogaster genome project, our results suggest that insects may have many tens of OBPs expressed in subsets of the chemosensory sensilla on their antennae. These results support a model for insect olfaction in which OBPs selectively transport and present odourants to transmembrane olfactory receptors. We also found five members of a family of shorter proteins, named sensory appendage proteins (SAPs), that might also be involved in odourant transport. This small EST project also revealed several candidate odourant degrading enzymes including three P450 cytochromes, a glutathione S-transferase and a uridine diphosphate (UDP) glucosyltransferase. Several first insect homologues of proteins known from vertebrates, the nematode Caenorhabditis elegans, yeast and bacteria were encountered, and most have now also been detected by the large D. melanogaster EST project. Only thriteen entirely novel proteins were encountered, some of which are likely to be cuticle proteins.
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Affiliation(s)
- H M Robertson
- Department of Entomology, University of Illinois at Urbana-Champaign 61801, USA
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46
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Abstract
Recent progress in understanding the principles and mechanisms in olfaction is the result of multidisciplinary research efforts that explored chemosensation by using a variety of model organisms. Studies on invertebrates, notably nematodes, insects, and crustaceans, to which diverse experimental approaches can be applied, have greatly helped elucidate various aspects of olfactory signaling. From the converging results of genetic, molecular, and physiological studies, a common set of chemosensory mechanisms emerges. Recognition and discrimination of odorants as well as chemo-electrical transduction and processing of olfactory signals appear to be mediated by fundamentally similar mechanisms in phylogenetically diverse animals. The common challenge of organisms to decipher the world of odors was apparently met by a phylogenetically conserved strategy. Thus, comparative studies should continue to provide important contributions toward an understanding of the sense of smell.
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Affiliation(s)
- J Krieger
- University of Stuttgart-Hohenheim, Institute of Physiology, Garbenstrasse 30, 70599 Stuttgart, Germany
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47
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Abstract
We have taken advantage of the availability of a large amount of Drosophila genomic DNA sequence in the Berkeley Drosophila Genome Project database ( approximately 1/5 of the genome) to identify a family of novel seven transmembrane domain encoding genes that are putative Drosophila olfactory receptors. Members of the family are expressed in distinct subsets of olfactory neurons, and certain family members are restricted to distinct portions of the olfactory system. This pattern of expression has interesting similarities to and differences from the expression patterns observed for olfactory receptors in vertebrates. The Drosophila olfactory system is simpler than mammalian systems, yet it is complex enough to present a fascinating system in which to study neural information processing. Moreover, the powerful genetic manipulations available in Drosophila, when combined with electrophysiological and behavioral analyses, make this an attractive model system in which to study olfactory discrimination.
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Affiliation(s)
- Q Gao
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, Massachusetts, 02142, USA
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Frémion F, Astier M, Zaffran S, Guillèn A, Homburger V, Sémériva M. The heterotrimeric protein Go is required for the formation of heart epithelium in Drosophila. J Cell Biol 1999; 145:1063-76. [PMID: 10352022 PMCID: PMC2133120 DOI: 10.1083/jcb.145.5.1063] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The gene encoding the alpha subunit of the Drosophila Go protein is expressed early in embryogenesis in the precursor cells of the heart tube, of the visceral muscles, and of the nervous system. This early expression coincides with the onset of the mesenchymal-epithelial transition to which are subjected the cardial cells and the precursor cells of the visceral musculature. This gene constitutes an appropriate marker to follow this transition. In addition, a detailed analysis of its expression suggests that the cardioblasts originate from two subpopulations of cells in each parasegment of the dorsal mesoderm that might depend on the wingless and hedgehog signaling pathways for both their determination and specification. In the nervous system, the expression of Goalpha shortly precedes the beginning of axonogenesis. Mutants produced in the Goalpha gene harbor abnormalities in the three tissues in which the gene is expressed. In particular, the heart does not form properly and interruptions in the heart epithelium are repeatedly observed, henceforth the brokenheart (bkh) name. Furthermore, in the bkh mutant embryos, the epithelial polarity of cardial cells was not acquired (or maintained) in various places of the cardiac tube. We predict that bkh might be involved in vesicular traffic of membrane proteins that is responsible for the acquisition of polarity.
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Affiliation(s)
- F Frémion
- Laboratoire de Génétique et Physiologie du Développement, UMR 6545 CNRS-Université, IBDM CNRS-INSERM-Université de la Méditerranée, Campus de Luminy, 13288 Marseille Cedex 09, France
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49
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Elmore T, Rodriguez A, Smith DP. dRGS7 encodes a Drosophila homolog of EGL-10 and vertebrate RGS7. DNA Cell Biol 1998; 17:983-9. [PMID: 9839808 DOI: 10.1089/dna.1998.17.983] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We identified a Drosophila gene encoding a homolog of the regulator of G-protein signaling (RGS) protein family. This gene (dRGS7) is expressed in neurons of the embryo and adult fly and is predicted to encode a 428-amino acid protein with >55% overall amino acid sequence identity with the vertebrate protein RGS7 and the C. elegans EGL-10. The dRGS7 protein is 50% conserved in the C-terminal RGS domain with RGS7 and EGL-10 but, remarkably, displays much greater conservation with the N-terminal regions of these proteins. This finding implies a conserved function for these homologs from divergent species involving domains outside the RGS domain. The dRGS7 protein also has a domain of similarity with Dishevelled and pleckstrin, raising the possibility that these proteins interact with common signaling components.
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Affiliation(s)
- T Elmore
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas 75235-9111, USA
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50
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Kim MS, Repp A, Smith DP. LUSH odorant-binding protein mediates chemosensory responses to alcohols in Drosophila melanogaster. Genetics 1998; 150:711-21. [PMID: 9755202 PMCID: PMC1460366 DOI: 10.1093/genetics/150.2.711] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The molecular mechanisms mediating chemosensory discrimination in insects are unknown. Using the enhancer trapping approach, we identified a new Drosophila mutant, lush, with odorant-specific defects in olfactory behavior. lush mutant flies are abnormally attracted to high concentrations of ethanol, propanol, and butanol but have normal chemosensory responses to other odorants. We show that wild-type flies have an active olfactory avoidance mechanism to prevent attraction to concentrated alcohol, and this response is defective in lush mutants. This suggests that the defective olfactory behavior associated with the lush mutation may result from a specific defect in chemoavoidance. lush mutants have a 3-kb deletion that produces a null allele of a new member of the invertebrate odorant-binding protein family, LUSH. LUSH is normally expressed exclusively in a subset of trichoid chemosensory sensilla located on the ventral-lateral surface of the third antennal segment. LUSH is secreted from nonneuronal support cells into the sensillum lymph that bathes the olfactory neurons within these sensilla. Reintroduction of a cloned wild-type copy of lush into the mutant background completely restores wild-type olfactory behavior, demonstrating that this odorant-binding protein is required in a subset of sensilla for normal chemosensory behavior to a subset of odorants. These findings provide direct evidence that odorant-binding proteins are required for normal chemosensory behavior in Drosophila and may partially determine the chemical specificity of olfactory neurons in vivo.
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Affiliation(s)
- M S Kim
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9111, USA
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