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A conserved aspartic acid is important for agonist (VUAA1) and odorant/tuning receptor-dependent activation of the insect odorant co-receptor (Orco). PLoS One 2013; 8:e70218. [PMID: 23894621 PMCID: PMC3720905 DOI: 10.1371/journal.pone.0070218] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/17/2013] [Indexed: 11/19/2022] Open
Abstract
Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco). An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca(2+) influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ~2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.
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252
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Carraher C, Nazmi AR, Newcomb RD, Kralicek A. Recombinant expression, detergent solubilisation and purification of insect odorant receptor subunits. Protein Expr Purif 2013; 90:160-9. [PMID: 23770557 DOI: 10.1016/j.pep.2013.06.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/31/2013] [Accepted: 06/04/2013] [Indexed: 12/16/2022]
Abstract
Insect odorant receptors (ORs) are seven transmembrane domain proteins that comprise a novel family of ligand-gated non-selective cation channels. The functional channel is made up of an odour activated ligand-binding OR and the OR co-receptor, Orco. However, the structure, stoichiometry and mechanism of activation of the receptor complex are not well understood. Here we demonstrate that baculovirus-mediated Sf9 cell expression and wheat germ cell-free expression, but not Escherichia coli cell-based or cell-free expression, can be used successfully to over-express a selection of insect ORs. From a panel of 19 detergents, 1%w/v Zwittergent 3-16 was able to solubilise five Drosophila melanogaster ORs produced from both eukaryotic expression systems. A large-scale purification protocol was then developed for DmOrco and the ligand-binding receptor, DmOr22a. The proteins were nickel-affinity purified using a deca-histidine tag in a buffer containing 0.2 mM Zwittergent 3-16, followed by size exclusion chromatography. These purified ORs appear to form similarly sized protein-detergent complexes when isolated from both expression systems. Circular dichroism analysis of both purified proteins suggests they are folded correctly. We also provide evidence that when DmOrco is expressed in Sf9 cells it undergoes post translational modification, probably glycosylation. Finally we show that the recombinant ORs can be incorporated into pre-formed liposomes. The ability to recombinantly express and purify insect ORs to homogeneity on a preparative scale, as well as insert them into liposomes, is a major step forward in enabling future structural and functional studies, as well as their use in OR based biosensors.
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Affiliation(s)
- Colm Carraher
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand
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253
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The Potential of 13C Isotopomers as a Test for the Vibrational Theory of Olfactory Sense Recognition. ISRN ORGANIC CHEMISTRY 2013; 2013:515810. [PMID: 24052862 PMCID: PMC3767358 DOI: 10.1155/2013/515810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 05/13/2013] [Indexed: 12/02/2022]
Abstract
The continuing debate over the basis of odorant recognition with respect to the molecular shape (“lock and key”) theory versus the vibrational theory could potentially be resolved by the testing of 13C-labeled odorants. The application of 13C isotopomers is discussed herein by means of DFT-calculated IR vibrations and Gibbs' free energies (ΔG) for acetophenone and octan-1-ol, two odorants for which the 2D (deuterium) isotopomers have previously been shown to be discernible from their respective 1H (normal) counterparts by Drosophila melanogaster.
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254
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Apps PJ. Are mammal olfactory signals hiding right under our noses? Naturwissenschaften 2013; 100:487-506. [DOI: 10.1007/s00114-013-1054-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/22/2013] [Accepted: 04/25/2013] [Indexed: 01/23/2023]
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255
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Ponissery Saidu S, Stephan AB, Talaga AK, Zhao H, Reisert J. Channel properties of the splicing isoforms of the olfactory calcium-activated chloride channel Anoctamin 2. ACTA ACUST UNITED AC 2013; 141:691-703. [PMID: 23669718 PMCID: PMC3664704 DOI: 10.1085/jgp.201210937] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anoctamin (ANO)2 (or TMEM16B) forms a cell membrane Ca(2+)-activated Cl(-) channel that is present in cilia of olfactory receptor neurons, vomeronasal microvilli, and photoreceptor synaptic terminals. Alternative splicing of Ano2 transcripts generates multiple variants with the olfactory variants skipping exon 14 and having alternative splicing of exon 4. In the present study, 5' rapid amplification of cDNA ends analysis was conducted to characterize the 5' end of olfactory Ano2 transcripts, which showed that the most abundant Ano2 transcripts in the olfactory epithelium contain a novel starting exon that encodes a translation initiation site, whereas transcripts of the publically available sequence variant, which has an alternative and longer 5' end, were present in lower abundance. With two alternative starting exons and alternative splicing of exon 4, four olfactory ANO2 isoforms are thus possible. Patch-clamp experiments in transfected HEK293T cells expressing these isoforms showed that N-terminal sequences affect Ca(2+) sensitivity and that the exon 4-encoded sequence is required to form functional channels. Coexpression of the two predominant isoforms, one with and one without the exon 4 sequence, as well as coexpression of the two rarer isoforms showed alterations in channel properties, indicating that different isoforms interact with each other. Furthermore, channel properties observed from the coexpression of the predominant isoforms better recapitulated the native channel properties, suggesting that the native channel may be composed of two or more splicing isoforms acting as subunits that together shape the channel properties.
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256
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Liu Y, Liu C, Lin K, Wang G. Functional specificity of sex pheromone receptors in the cotton bollworm Helicoverpa armigera. PLoS One 2013; 8:e62094. [PMID: 23614018 PMCID: PMC3626661 DOI: 10.1371/journal.pone.0062094] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/16/2013] [Indexed: 11/19/2022] Open
Abstract
Male moths can accurately perceive the sex pheromone emitted from conspecific females by their highly accurate and specific olfactory sensory system. Pheromone receptors are of special importance in moth pheromone reception because of their central role in chemosensory signal transduction processes that occur in olfactory receptor neurons in the male antennae. There are a number of pheromone receptor genes have been cloned, however, only a few have been functionally characterized. Here we cloned six full-length pheromone receptor genes from Helicoverpa armigera male antennae. Real-time PCR showing all genes exhibited male-biased expression in adult antennae. Functional analyses of the six pheromone receptor genes were then conducted in the heterologous expression system of Xenopus oocytes. HarmOR13 was found to be a specific receptor for the major sex pheromone component Z11-16:Ald. HarmOR6 was equally tuned to both of Z9-16: Ald and Z9-14: Ald. HarmOR16 was sensitively tuned to Z11-16: OH. HarmOR11, HarmOR14 and HarmOR15 failed to respond to the tested candidate pheromone compounds. Our experiments elucidated the functions of some pheromone receptor genes of H. armigera. These advances may provide remarkable evidence for intraspecific mating choice and speciation extension in moths at molecular level.
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Affiliation(s)
- Yang Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Chengcheng Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Kejian Lin
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Guirong Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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257
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Ukhanov K, Corey EA, Ache BW. Phosphoinositide 3-kinase dependent inhibition as a broad basis for opponent coding in Mammalian olfactory receptor neurons. PLoS One 2013; 8:e61553. [PMID: 23585911 PMCID: PMC3621990 DOI: 10.1371/journal.pone.0061553] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/11/2013] [Indexed: 11/18/2022] Open
Abstract
Phosphoinositide 3-kinase (PI3K) signaling has been implicated in mediating inhibitory odorant input to mammalian olfactory receptor neurons (ORNs). To better understand the breadth of such inhibition in odor coding, we screened a panel of odorants representing different chemical classes, as well as odorants known to occur in a natural odor object (tomato), for their ability to rapidly activate PI3K-dependent inhibitory signaling. Odorants were screened on dissociated native rat ORNs before and after pre-incubation with the PI3K-isoform specific blockers AS252424 and TGX221. Many different odorants increased their excitatory strength for particular ORNs following PI3K blockade in a manner consistent with activating PI3K-dependent inhibitory signaling in those cells. The PI3K-dependent inhibitory odorants overlapped with conventional excitatory odorants, but did not share the same bias, indicating partial partitioning of the odor space. Finding that PI3K-dependent inhibition can be activated by a wide range of otherwise conventional excitatory odorants strongly implies PI3K-dependent inhibition provides a broad basis for opponent coding in mammalian ORNs.
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Affiliation(s)
- Kirill Ukhanov
- Whitney Laboratory, Center for Smell and Taste, McKnight Brain Institute; University of Florida, Gainesville, Florida, United States of America.
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258
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Kaissling KE. Kinetics of olfactory responses might largely depend on the odorant-receptor interaction and the odorant deactivation postulated for flux detectors. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2013; 199:879-96. [PMID: 23563709 DOI: 10.1007/s00359-013-0812-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/05/2013] [Accepted: 03/10/2013] [Indexed: 11/28/2022]
Abstract
Experimental data together with modeling of pheromone perireceptor and receptor events in moths (Bombyx mori, Antheraea polyphemus) suggest that the kinetics of olfactory receptor potentials largely depend on the association of the odorant with the neuronal receptor molecules and the deactivation of the odorant accumulated around the receptor neuron. The first process could be responsible for the reaction times (mean about 400 ms) of the nerve impulses at threshold. The second process has been postulated for flux detectors such as olfactory sensilla of moths. The odorant deactivation could involve a modification of the pheromone-binding protein (PBP) that "locks" the pheromone inside the inner binding cavity of the protein. The model combines seemingly contradictory functions of the PBP such as pheromone transport, protection of the pheromone from enzymatic degradation, pheromone deactivation, and pheromone-receptor interaction. Model calculations reveal a density of at least 6,000 receptor molecules per µm(2) of neuronal membrane. The volatile decanoyl-thio-1,1,1-trifluoropropanone specifically blocks pheromone receptor neurons, probably when bound to the PBP and by competitive binding to the receptor molecules. The shallow dose-response curve of the receptor potential and altered response properties observed with pheromone derivatives or after adaptation may indicate shortened opening of ion channels.
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Affiliation(s)
- Karl-Ernst Kaissling
- Max-Planck-Institut fuer Verhaltensphysiologie/Ornithologie, Seewiesen, 82319, Starnberg, Germany,
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259
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Abstract
The nature of the olfactory receptor in crustaceans, a major group of arthropods, has remained elusive. We report that spiny lobsters, Panulirus argus, express ionotropic receptors (IRs), the insect chemosensory variants of ionotropic glutamate receptors. Unlike insects IRs, which are expressed in a specific subset of olfactory cells, two lobster IR subunits are expressed in most, if not all, lobster olfactory receptor neurons (ORNs), as confirmed by antibody labeling and in situ hybridization. Ligand-specific ORN responses visualized by calcium imaging are consistent with a restricted expression pattern found for other potential subunits, suggesting that cell-specific expression of uncommon IR subunits determines the ligand sensitivity of individual cells. IRs are the only type of olfactory receptor that we have detected in spiny lobster olfactory tissue, suggesting that they likely mediate olfactory signaling. Given long-standing evidence for G protein-mediated signaling in activation of lobster ORNs, this finding raises the interesting specter that IRs act in concert with second messenger-mediated signaling.
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260
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Andersson MN, Grosse-Wilde E, Keeling CI, Bengtsson JM, Yuen MMS, Li M, Hillbur Y, Bohlmann J, Hansson BS, Schlyter F. Antennal transcriptome analysis of the chemosensory gene families in the tree killing bark beetles, Ips typographus and Dendroctonus ponderosae (Coleoptera: Curculionidae: Scolytinae). BMC Genomics 2013; 14:198. [PMID: 23517120 PMCID: PMC3610139 DOI: 10.1186/1471-2164-14-198] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/13/2013] [Indexed: 12/05/2022] Open
Abstract
Background The European spruce bark beetle, Ips typographus, and the North American mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Curculionidae: Scolytinae), are severe pests of coniferous forests. Both bark beetle species utilize aggregation pheromones to coordinate mass-attacks on host trees, while odorants from host and non-host trees modulate the pheromone response. Thus, the bark beetle olfactory sense is of utmost importance for fitness. However, information on the genes underlying olfactory detection has been lacking in bark beetles and is limited in Coleoptera. We assembled antennal transcriptomes from next-generation sequencing of I. typographus and D. ponderosae to identify members of the major chemosensory multi-gene families. Results Gene ontology (GO) annotation indicated that the relative abundance of transcripts associated with specific GO terms was highly similar in the two species. Transcripts with terms related to olfactory function were found in both species. Focusing on the chemosensory gene families, we identified 15 putative odorant binding proteins (OBP), 6 chemosensory proteins (CSP), 3 sensory neuron membrane proteins (SNMP), 43 odorant receptors (OR), 6 gustatory receptors (GR), and 7 ionotropic receptors (IR) in I. typographus; and 31 putative OBPs, 11 CSPs, 3 SNMPs, 49 ORs, 2 GRs, and 15 IRs in D. ponderosae. Predicted protein sequences were compared with counterparts in the flour beetle, Tribolium castaneum, the cerambycid beetle, Megacyllene caryae, and the fruit fly, Drosophila melanogaster. The most notable result was found among the ORs, for which large bark beetle-specific expansions were found. However, some clades contained receptors from all four beetle species, indicating a degree of conservation among some coleopteran OR lineages. Putative GRs for carbon dioxide and orthologues for the conserved antennal IRs were included in the identified receptor sets. Conclusions The protein families important for chemoreception have now been identified in three coleopteran species (four species for the ORs). Thus, this study allows for improved evolutionary analyses of coleopteran olfaction. Identification of these proteins in two of the most destructive forest pests, sharing many semiochemicals, is especially important as they might represent novel targets for population control.
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Affiliation(s)
- Martin N Andersson
- Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, SE-230 53, Alnarp, Sweden.
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261
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Kruangkum T, Chotwiwatthanakun C, Vanichviriyakit R, Tinikul Y, Anuracpreeda P, Wanichanon C, Hanna PJ, Sobhon P. Structure of the olfactory receptor organs, their GABAergic neural pathways, and modulation of mating behavior, in the giant freshwater prawn, Macrobrachium rosenbergii. Microsc Res Tech 2013; 76:572-87. [PMID: 23495186 DOI: 10.1002/jemt.22202] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 02/05/2013] [Accepted: 02/08/2013] [Indexed: 12/24/2022]
Abstract
In the giant male prawn, Macrobrachium rosenbergii, the olfactory system is thought to be the main pathway for modulating sexual behavior through pheromone perception. In this report, we first used gross anatomical, histological, and SEM methods to describe the structures of the olfactory receptors (sensilla setae), their neural pathways, and possible role in modulating mating behavior. On the surfaces of antennule and antenna filaments there are four types of sensory receptors, viz single spike-like setae, single flagellum-like setae, multiple flagella-like setae, and aesthetascs (ASs). The ASs, which had previously been proposed to be odor receptor setae, are found only on the short filament of lateral antennule (slAn). Each AS on the slAn connects with olfactory receptor neurons (ORNs), whose axons form an outer central antennule nerve (ocAnNv), which then connects with the olfactory neutrophil (ON) of the brain. Thus, the slAn is the major olfactory organ that conveys sensory inputs from each AS to the ON within the deutocerebrum. GABA immunoreactivity was present in ASs, neurons of ORNs, inner central antennular, lateral tegumentary nerve, ocAnNv and the ON, inferring that GABA is the likely neurotransmitter in modulating olfaction. Disruption of the slAn by ablation or covering with Vaseline, resulted in significant reduction of mating behavior, indicating that this organ is crucial for sex pheromone perception. Identification of the active pheromones and further bioassays are now being performed.
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Affiliation(s)
- Thanapong Kruangkum
- Department of Anatomy, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
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262
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Gancedo JM. Biological roles of cAMP: variations on a theme in the different kingdoms of life. Biol Rev Camb Philos Soc 2013; 88:645-68. [PMID: 23356492 DOI: 10.1111/brv.12020] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 12/19/2012] [Accepted: 12/20/2012] [Indexed: 12/18/2022]
Abstract
Cyclic AMP (cAMP) plays a key regulatory role in most types of cells; however, the pathways controlled by cAMP may present important differences between organisms and between tissues within a specific organism. Changes in cAMP levels are caused by multiple triggers, most affecting adenylyl cyclases, the enzymes that synthesize cAMP. Adenylyl cyclases form a large and diverse family including soluble forms and others with one or more transmembrane domains. Regulatory mechanisms for the soluble adenylyl cyclases involve either interaction with diverse proteins, as happens in Escherichia coli or yeasts, or with calcium or bicarbonate ions, as occurs in mammalian cells. The transmembrane cyclases can be regulated by a variety of proteins, among which the α subunit and the βγ complex from G proteins coupled to membrane receptors are prominent. cAMP levels also are controlled by the activity of phosphodiesterases, enzymes that hydrolyze cAMP. Phosphodiesterases can be regulated by cAMP, cGMP or calcium-calmodulin or by phosphorylation by different protein kinases. Regulation through cAMP depends on its binding to diverse proteins, its proximal targets, this in turn causing changes in a variety of distal targets. Specifically, binding of cAMP to regulatory subunits of cAMP-dependent protein kinases (PKAs) affects the activity of substrates of PKA, binding to exchange proteins directly activated by cAMP (Epac) regulates small GTPases, binding to transcription factors such as the cAMP receptor protein (CRP) or the virulence factor regulator (Vfr) modifies the rate of transcription of certain genes, while cAMP binding to ion channels modulates their activity directly. Further studies on cAMP signalling will have important implications, not only for advancing fundamental knowledge but also for identifying targets for the development of new therapeutic agents.
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Affiliation(s)
- Juana M Gancedo
- Department of Metabolism and Cell Signalling, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid 28029, Spain.
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263
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Pask GM, Bobkov YV, Corey EA, Ache BW, Zwiebel LJ. Blockade of insect odorant receptor currents by amiloride derivatives. Chem Senses 2013; 38:221-9. [PMID: 23292750 DOI: 10.1093/chemse/bjs100] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Insect odorant receptors (ORs) function as heteromeric odorant-gated ion channels consisting of a conserved coreceptor, Orco, and an odorant-sensitive tuning subunit. Although some OR modulators have been identified, an extended library of pharmacological tools is currently lacking and would aid in furthering our understanding of insect OR complexes. We now demonstrate that amiloride and several derivatives, which have been extensively used as blockers for various ion channels and transporters, also block odorant-gated currents from 2 OR complexes from the malaria vector mosquito Anopheles gambiae. In addition, both heteromeric and homomeric ORs were susceptible to amiloride blockade when activated by VUAA1, an agonist that targets the Orco channel subunit. Amiloride derivatives therefore represent a valuable class of channel blockers that can be used to investigate the pharmacological and biophysical properties of insect OR function.
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Affiliation(s)
- Gregory M Pask
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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264
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Abstract
Olfactory receptors (ORs) constitute the largest gene family in the mammalian genome. The existence of these proteins underlies the nature of, and variability in, odorant perception. The Human Olfactory Receptor Data Explorer (HORDE, http://genome.weizmann.ac.il/horde/ ) is a free online resource, which presents a complete compendium of all OR genes and pseudogenes in the genome of human and four other vertebrates. HORDE includes three parts: (1) an automated pipeline, which mines OR gene and pseudogene sequences out of complete genomes, and generates gene symbols based on sequence similarity; (2) a card generator that obtains and displays annotative information on individual ORs retrieved from external databases and relevant studies; and (3) a search engine that allows user retrieval of OR information. For human ORs, HORDE specifically addresses the universe of interindividual variation, as obtained from several sources, including whole genome sequences made possible by next-generation sequencing. This encompasses single nucleotide polymorphisms (SNP) and copy number variation (CNV), including deleterious mutational events. HORDE also hosts a number of tools designed specifically to assist in the study of OR evolution and function. In this chapter, we describe the status of HORDE (build #43). We also discuss plans for future enhancements and a road map for HORDE to become a better community-based bioinformatics tool. We highlight HORDE's role as a major research tool in the study of an expanding cohort of OR repertoires.
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Affiliation(s)
- Tsviya Olender
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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265
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Abstract
Sensory neurons in the vomeronasal organ (VNO) are thought to mediate a specialized olfactory response. Currently, very little is known about the identity of stimulating ligands or their cognate receptors that initiate neural activation. Each sensory neuron is thought to express 1 of approximately 250 variants of Vmn1Rs, Vmn2Rs (A, B, or D), or FPRs which enables it to be tuned to a subset of ligands (Touhara and Vosshall, Annu Rev Physiol 71:307-332, 2009). The logic of how different sources of native odors or purified ligands are detected by this complex sensory repertoire remains mostly unknown. Here, we describe a method to compare and analyze the response of VNO sensory neurons to multiple stimuli using conventional calcium imaging. This method differs from other olfactory imaging approaches in that we dissociate the tightly packed sensory epithelium into individual single cells. The advantages of this approach include (1) the use of a relatively simple approach and inexpensive microscopy, (2) comparative analysis of several hundreds of neurons to multiple stimuli with single-cell resolution, and (3) the possibility of isolating single cells of interest to further analyze by molecular biology techniques including in situ RNA hybridization, immunofluorescence, or creating single-cell cDNA libraries (Malnic et al., Cell 96:713-723, 1999).
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266
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Vásquez GM, Syed Z, Estes PA, Leal WS, Gould F. Specificity of the receptor for the major sex pheromone component in Heliothis virescens. JOURNAL OF INSECT SCIENCE (ONLINE) 2013; 13:160. [PMID: 24773407 PMCID: PMC4015405 DOI: 10.1673/031.013.16001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 10/29/2012] [Indexed: 06/03/2023]
Abstract
In a previous study, the Drosophila melanogaster OR67d(GAL4);UAS system was used to functionally characterize the receptor for the major component of the sex pheromone in the tobacco budworm, Heliothis virescens Fabricius (Lepidoptera: Noctuidae), HvOR13. Electrophysiological and behavioral assays showed that transgenic flies expressing HvOR13 responded to (Z)-11-hexadecenal (Z11-16:Ald). However, tests were not performed to determine whether these flies would also respond to secondary components of the H. virescens sex pheromone. Thus, in this study the response spectrum of HvOR13 expressed in this system was examined by performing single cell recordings from odor receptor neuron in trichoid T1 sensilla on antennae of two Or67d(GAL4 [1]); UAS-HvOR13 lines stimulated with Z11-16:Ald and six H. virescens secondary pheromone components. Fly courtship assays were also performed to examine the behavioral response of the Or67d(GAL4[1]); UAS-HvOR13 flies to Z11-16:Ald and the secondary component Z9-14:Ald. Our combined electrophysiological and behavioral studies indicated high specificity and sensitivity of HvOR13 to Z11-16:Ald. Interestingly, a mutation leading to truncation in the HvOR13 C-terminal region affected but did not abolish pheromone receptor response to Z11-16:Ald. The findings are assessed in relationship to other HvOR13 heterologous expression studies, and the role of the C-terminal domain in receptor function is discussed. A third line expressing HvOR15 was also tested but did not respond to any of the seven pheromone components.
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Affiliation(s)
- Gissella M. Vásquez
- Department of Entomology and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Zainulabeuddin Syed
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Patricia A. Estes
- Department of Biological Sciences and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Walter S. Leal
- Department of Entomology, Honorary Maeda-Duffey Laboratory, University of California, Davis, CA 95616, USA
| | - Fred Gould
- Department of Entomology and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695, USA
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267
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Nehring V, Wyatt TD, d’Ettorre P. Noise in Chemical Communication. ANIMAL SIGNALS AND COMMUNICATION 2013. [DOI: 10.1007/978-3-642-41494-7_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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268
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Pask GM, Romaine IM, Zwiebel LJ. The molecular receptive range of a lactone receptor in Anopheles gambiae. Chem Senses 2013; 38:19-25. [PMID: 22944613 PMCID: PMC3522515 DOI: 10.1093/chemse/bjs074] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In an environment filled with a complex spectrum of chemical stimuli, insects rely on the specificity of odorant receptors (ORs) to discern odorants of ecological importance. In nature, cyclic esters, or lactones, represent a common class of semiochemicals that exhibit a range of diversity through ring size and substituents, as well as stereochemistry. We have used heterologous expression to explore the lactone sensitivity of AgOr48, an odorant-sensitive OR from the principal malaria vector mosquito, Anopheles gambiae. Voltage clamp and calcium-imaging experiments revealed that AgOr48 is particularly sensitive to changes in the size of the lactone ring and in the length of the carbon chain substituent. In addition, the two enantiomers of a strong agonist, δ-decalactone, elicited significantly different potency values, implicating AgOr48 as an enantioselective odorant receptor. Investigation of the molecular receptive range of this lactone receptor may contribute to a greater understanding of ligand-OR interactions and provide insight into the chemical ecology of An. gambiae.
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Affiliation(s)
- Gregory M Pask
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennesse, USA.
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269
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Lodovichi C, Belluscio L. Odorant receptors in the formation of the olfactory bulb circuitry. Physiology (Bethesda) 2012; 27:200-12. [PMID: 22875451 DOI: 10.1152/physiol.00015.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In mammals, smell is mediated by odorant receptors expressed by sensory neurons in the nose. These specialized receptors are found both on olfactory sensory neurons' cilia and axon terminals. Although the primary function of ciliary odorant receptors is to detect odorants, their axonal role remains unclear but is thought to involve axon guidance. This review discusses findings that show axonal odorant receptors are indeed functional and capable of modulating neural connectivity.
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Affiliation(s)
- Claudia Lodovichi
- Venetian Institute of Molecular Medicine, and Institute of Neuroscience-CNR, Padua, Italy
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270
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Hassenklöver T, Pallesen LP, Schild D, Manzini I. Amino acid- vs. peptide-odorants: responses of individual olfactory receptor neurons in an aquatic species. PLoS One 2012; 7:e53097. [PMID: 23300867 PMCID: PMC3531423 DOI: 10.1371/journal.pone.0053097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/23/2012] [Indexed: 12/17/2022] Open
Abstract
Amino acids are widely used waterborne olfactory stimuli proposed to serve as cues in the search for food. In natural waters the main source of amino acids is the decomposition of proteins. But this process also produces a variety of small peptides as intermediate cleavage products. In the present study we tested whether amino acids actually are the natural and adequate stimuli for the olfactory receptors they bind to. Alternatively, these olfactory receptors could be peptide receptors which also bind amino acids though at lower affinity. Employing calcium imaging in acute slices of the main olfactory epithelium of the fully aquatic larvae of Xenopus laevis we show that amino acids, and not peptides, are more effective waterborne odorants.
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Affiliation(s)
- Thomas Hassenklöver
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
| | - Lars P. Pallesen
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
| | - Detlev Schild
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
| | - Ivan Manzini
- Department of Neurophysiology and Cellular Biophysics, University of Göttingen, Göttingen, Germany
- Cluster of Excellence “Nanoscale Microscopy and Molecular Physiology of the Brain” (CNMPB), University of Göttingen, Göttingen, Germany
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271
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François A, Grauso M, Demondion E, Bozzolan F, Debernard S, Lucas P. Bestrophin-encoded Ca²⁺-activated Cl⁻ channels underlie a current with properties similar to the native current in the moth Spodoptera littoralis olfactory receptor neurons. PLoS One 2012; 7:e52691. [PMID: 23300744 PMCID: PMC3530479 DOI: 10.1371/journal.pone.0052691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 11/20/2012] [Indexed: 11/19/2022] Open
Abstract
Responses of insect olfactory receptor neurons (ORNs) involve an entry of Ca2+ through olfactory heterodimeric receptor complexes. In moths, the termination of ORN responses was found to strongly depend on the external Ca2+ concentration through the activation of unknown Ca2+-dependent Cl− channels. We thus investigated the molecular identity of these Cl− channels. There is compelling evidence that bestrophins form Cl− channels when expressed in heterologous systems. Here we provide evidence that antennae of the moth Spodoptera littoralis express three transcripts encoding proteins with hallmarks of bestrophins. One of these transcripts, SlitBest1b, is expressed in ORNs. The heterologous expression of SlitBest1b protein in CHO-K1 cells yielded a Ca2+-activated Cl− current that shares electrophysiological properties with the native Ca2+-activated Cl− current of ORNs. Both currents are anionic, present similar dependence on the intracellular Ca2+ concentration, partly inactivate over time, have the same anion permeability sequence, the same sequence of inhibitory efficiency of blockers, the same almost linear I–V relationships and finally both currents do not depend on the cell volume. Therefore, our data suggest that SlitBest1b is a good candidate for being a molecular component of the olfactory Ca2+-activated Cl− channel and is likely to constitute part of the insect olfactory transduction pathway. A different function (e.g. regulation of other proteins, maintenance of the anionic homeostasis in the sensillar lymph) and a different role (e.g. involvement in the olfactory system development) cannot be excluded however.
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Affiliation(s)
- Adrien François
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
- Université Pierre et Marie Curie, UMR 1272 Physiologie de l’Insecte: Signalisation et Communication, Paris, France
| | - Marta Grauso
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
| | - Elodie Demondion
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
| | - Françoise Bozzolan
- Université Pierre et Marie Curie, UMR 1272 Physiologie de l’Insecte: Signalisation et Communication, Paris, France
| | - Stéphane Debernard
- Université Pierre et Marie Curie, UMR 1272 Physiologie de l’Insecte: Signalisation et Communication, Paris, France
| | - Philippe Lucas
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
- * E-mail:
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272
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Schneider A, Ruppert M, Hendrich O, Giang T, Ogueta M, Hampel S, Vollbach M, Büschges A, Scholz H. Neuronal basis of innate olfactory attraction to ethanol in Drosophila. PLoS One 2012; 7:e52007. [PMID: 23284851 PMCID: PMC3527413 DOI: 10.1371/journal.pone.0052007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 11/07/2012] [Indexed: 12/19/2022] Open
Abstract
The decision to move towards a mating partner or a food source is essential for life. The mechanisms underlying these behaviors are not well understood. Here, we investigated the role of octopamine - the invertebrate analogue of noradrenaline - in innate olfactory attraction to ethanol. We confirmed that preference is caused via an olfactory stimulus by dissecting the function of the olfactory co-receptor Orco (formally known as OR83b). Orco function is not required for ethanol recognition per se, however it plays a role in context dependent recognition of ethanol. Odor-evoked ethanol preference requires the function of Tbh (Tyramine β hydroxalyse), the rate-limiting enzyme of octopamine synthesis. In addition, neuronal activity in a subset of octopaminergic neurons is necessary for olfactory ethanol preference. Notably, a specific neuronal activation pattern of tyraminergic/octopaminergic neurons elicit preference and is therefore sufficient to induce preference. In contrast, dopamine dependent increase in locomotor activity is not sufficient for olfactory ethanol preference. Consistent with the role of noradrenaline in mammalian drug induced rewards, we provide evidence that in adult Drosophila the octopaminergic neurotransmitter functions as a reinforcer and that the molecular dissection of the innate attraction to ethanol uncovers the basic properties of a response selection system.
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Affiliation(s)
- Andrea Schneider
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
| | - Manuela Ruppert
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
| | - Oliver Hendrich
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
| | - Thomas Giang
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
| | - Maite Ogueta
- Instituto de Neurociencias de Castilla y León, Departmento Biología Celular y Patología, Salamanca, Spain
| | - Stefanie Hampel
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia, United States of America
| | - Marvin Vollbach
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
| | - Ansgar Büschges
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
| | - Henrike Scholz
- University of Cologne, Biocenter, Zoological Institute, Department of Animal Physiology/Neurobiology, Cologne, Germany
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273
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Dib-Hajj SD, Yang Y, Black JA, Waxman SG. The NaV1.7 sodium channel: from molecule to man. Nat Rev Neurosci 2012; 14:49-62. [DOI: 10.1038/nrn3404] [Citation(s) in RCA: 377] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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274
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Ogoma SB, Moore SJ, Maia MF. A systematic review of mosquito coils and passive emanators: defining recommendations for spatial repellency testing methodologies. Parasit Vectors 2012; 5:287. [PMID: 23216844 PMCID: PMC3549831 DOI: 10.1186/1756-3305-5-287] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 11/29/2012] [Indexed: 11/16/2022] Open
Abstract
Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS), long lasting insecticide treated nets (LLINs) and insecticide treated materials (ITMs). PubMed, (National Centre for Biotechnology Information (NCBI), U.S. National Library of Medicine, NIH), MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words “Mosquito coils” “Mosquito emanators” and “Spatial repellents”. It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose–response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP), which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control.
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Affiliation(s)
- Sheila B Ogoma
- Environmental Thematic Group, Ifakara Health Institute, Ifakara, Morogoro, United Republic of Tanzania.
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275
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Hull JJ, Hoffmann EJ, Perera OP, Snodgrass GL. Identification of the western tarnished plant bug (Lygus hesperus) olfactory co-receptor Orco: expression profile and confirmation of atypical membrane topology. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2012; 81:179-198. [PMID: 22836832 DOI: 10.1002/arch.21042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Lygus hesperus (western tarnished plant bug) is an agronomically important pest species of numerous cropping systems. Similar to other insects, a critical component underlying behaviors is the perception and discrimination of olfactory cues. Consequently, the molecular basis of olfaction in this species is of interest. To begin to address this issue, we utilized homology-based PCR as a commonly accepted abbreviation but if necessary it is polymerase chain reaction methods to identify the L. hesperus olfactory receptor co-receptor (Orco) ortholog, a receptor that has been shown to be essential for olfaction. The L. hesperus Orco (LhOrco) shares significant sequence homology with known Orco proteins in other insects. Parallel experiments using the sympatric sister species, Lygus lineolaris (tarnished plant bug), revealed that the Lygus Orco gene was completely conserved. Surprisingly, a majority of the membrane topology prediction algorithms used in the study predicted LhOrco to have both the N and C terminus intracellular. In vitro immunofluorescent microscopy experiments designed to probe the membrane topology of transiently expressed LhOrco, however, refuted those predictions and confirmed that the protein adopts the inverted topology (intracellular N terminus and an extracellular C terminus) characteristic of Orco proteins. RT-PCR analyses indicated that LhOrco transcripts are predominantly expressed in adult antennae and to a lesser degree in traditionally nonolfactory chemosensory tissues of the proboscis and legs. Expression is not developmentally regulated because transcripts were detected in all nymphal stages as well as eggs. Taken together, the results suggest that LhOrco likely plays a critical role in mediating L. hesperus odorant perception and discrimination.
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Affiliation(s)
- J Joe Hull
- USDA-ARS Arid Land Agricultural Research Center, Maricopa, AZ, USA.
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276
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Primary culture of embryonic rat olfactory receptor neurons. In Vitro Cell Dev Biol Anim 2012; 48:650-9. [PMID: 23150136 DOI: 10.1007/s11626-012-9560-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
Embryonic cells are very robust in surviving dissection and culturing protocols and easily adapt to their in vitro environment. Despite these advantages, research in the olfactory field on cultured embryonic olfactory neurons is sparse. In this study, two primary rat olfactory explant cultures of different embryonic d (E17 and E20) were established, comprising epithelium and bulb. The functionality of these neurons was tested by measuring intracellular calcium responses to cAMP-inducing agents forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX) with fluorescence microscopy. For E17, the responsive cell fraction increased over time, from an initial 3% at the 1 d in vitro (DIV) to a maximum of 19% at 11 DIV. The response of E20 neurons fluctuated over time around a more or less stable 13%. A logistic regression analysis indicated a significant difference between both embryonic d in the response to FSK + IBMX. In addition, of these functional neurons, 23.3% of E17 and 54.3% of E20 cultures were responsive to the odorant isoamyl acetate.
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277
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Bepari AK, Watanabe K, Yamaguchi M, Tamamaki N, Takebayashi H. Visualization of odor-induced neuronal activity by immediate early gene expression. BMC Neurosci 2012; 13:140. [PMID: 23126335 PMCID: PMC3538715 DOI: 10.1186/1471-2202-13-140] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 10/31/2012] [Indexed: 12/15/2022] Open
Abstract
Background Sensitive detection of sensory-evoked neuronal activation is a key to mechanistic understanding of brain functions. Since immediate early genes (IEGs) are readily induced in the brain by environmental changes, tracing IEG expression provides a convenient tool to identify brain activity. In this study we used in situ hybridization to detect odor-evoked induction of ten IEGs in the mouse olfactory system. We then analyzed IEG induction in the cyclic nucleotide-gated channel subunit A2 (Cnga2)-null mice to visualize residual neuronal activity following odorant exposure since CNGA2 is a key component of the olfactory signal transduction pathway in the main olfactory system. Results We observed rapid induction of as many as ten IEGs in the mouse olfactory bulb (OB) after olfactory stimulation by a non-biological odorant amyl acetate. A robust increase in expression of several IEGs like c-fos and Egr1 was evident in the glomerular layer, the mitral/tufted cell layer and the granule cell layer. Additionally, the neuronal IEG Npas4 showed steep induction from a very low basal expression level predominantly in the granule cell layer. In Cnga2-null mice, which are usually anosmic and sexually unresponsive, glomerular activation was insignificant in response to either ambient odorants or female stimuli. However, a subtle induction of c-fos took place in the OB of a few Cnga2-mutants which exhibited sexual arousal. Interestingly, very strong glomerular activation was observed in the OB of Cnga2-null male mice after stimulation with either the neutral odor amyl acetate or the predator odor 2, 3, 5-trimethyl-3-thiazoline (TMT). Conclusions This study shows for the first time that in vivo olfactory stimulation can robustly induce the neuronal IEG Npas4 in the mouse OB and confirms the odor-evoked induction of a number of IEGs. As shown in previous studies, our results indicate that a CNGA2-independent signaling pathway(s) may activate the olfactory circuit in Cnga2-null mice and that neuronal activation which correlates to behavioral difference in individual mice is detectable by in situ hybridization of IEGs. Thus, the in situ hybridization probe set we established for IEG tracing can be very useful to visualize neuronal activity at the cellular level.
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Affiliation(s)
- Asim K Bepari
- Department of Morphological Neural Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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278
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Keil TA. Sensory cilia in arthropods. ARTHROPOD STRUCTURE & DEVELOPMENT 2012; 41:515-34. [PMID: 22814269 DOI: 10.1016/j.asd.2012.07.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/29/2012] [Accepted: 07/03/2012] [Indexed: 05/11/2023]
Abstract
In arthropods, the modified primary cilium is a structure common to all peripheral sensory neurons other than photoreceptors. Since its first description in 1958, it has been investigated in great detail in numerous sense organs (sensilla) of many insect species by means of electron microscopy and electrophysiology. The perfection of molecular biological methods has led to an enormous advance in our knowledge about development and function of sensory cilia in the fruitfly since the end of the last century. The cilia show a wealth of adaptations according to their different physiological roles: chemoreception, mechanoreception, hygroreception, and thermoreception. Divergent types of receptors and channels have evolved fulfilling these tasks. The number of olfactory receptor genes can be close to 300 in ants, whereas in crickets slightest mechanical stimuli are detected by the interaction of extremely sophisticated biomechanical devices with mechanosensory cilia. Despite their enormous morphological and physiological divergence, sensilla and sensory cilia develop according to a stereotyped pattern. Intraflagellar transport genes have been found to be decisive for proper development and function.
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Affiliation(s)
- Thomas A Keil
- Max-Planck-Institute of Biochemistry, Department of Molecular Structural Biology, Martinsried, Germany.
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279
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Wicher D. Functional and evolutionary aspects of chemoreceptors. Front Cell Neurosci 2012; 6:48. [PMID: 23112762 PMCID: PMC3481119 DOI: 10.3389/fncel.2012.00048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 10/08/2012] [Indexed: 02/04/2023] Open
Abstract
The perception and processing of chemical signals from the environment is essential for any living systems and is most probably the first sense developed in life. This perspective discusses the physical limits of chemoreception and gives an overview on the receptor types developed during evolution to detect chemical signals from the outside world of an organism. It discusses the interaction of chemoreceptors with downstream signaling elements, especially the interaction between electrical and chemical signaling. It is further considered how the primary chemosignal is appropriately amplified. Three examples of chemosensory systems illustrate different strategies of such amplification.
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Affiliation(s)
- Dieter Wicher
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology Jena, Germany
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280
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Taylor RW, Romaine IM, Liu C, Murthi P, Jones PL, Waterson AG, Sulikowski GA, Zwiebel LJ. Structure-activity relationship of a broad-spectrum insect odorant receptor agonist. ACS Chem Biol 2012; 7:1647-52. [PMID: 22924767 DOI: 10.1021/cb300331z] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Agonism of insect odorant receptor (OR) cation channels may represent a new strategy for the manipulation of destructive insect olfactory-driven behaviors. We have explored the chemical space around VUAA1, the first in class agonist of the obligate OR co-receptor ion channel (Orco), and describe novel compound analogues with increased potency across insect taxa. Functional analyses reveal several of these VUAA1 structural analogues display significantly greater potency as compared to the activity of the previously described active compounds in mobility-based behavioral assays on mosquito larvae.
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Affiliation(s)
- Robert W. Taylor
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Ian M. Romaine
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Chao Liu
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Poornima Murthi
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Patrick L. Jones
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Alex G. Waterson
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Gary A. Sulikowski
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
| | - Laurence J. Zwiebel
- Department
of Biological Sciences, and ‡Department of Chemistry, Vanderbilt Institute of
Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pharmacology, and ∥Center for Molecular Neuroscience, Institute of Global Health and
Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37235,
United States
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281
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Characterization of a plasma membrane Ca(2+) ATPase expressed in olfactory receptor neurons of the moth Spodoptera littoralis. Cell Tissue Res 2012; 350:239-50. [PMID: 22965226 DOI: 10.1007/s00441-012-1483-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/12/2012] [Indexed: 10/27/2022]
Abstract
The response of insect olfactory receptor neurons (ORNs) involves an increase in intracellular Ca(2+) concentration, as in vertebrate ORNs. In order to decipher the Ca(2+) clearance mechanisms in insect ORNs, we have investigated the presence of a plasma membrane Ca(2+) ATPase (PMCA) in the peripheral olfactory system of the moth Spodoptera littoralis. From an analysis of a male antennal expressed-sequence-tag database combined with a strategy of 5'/3' rapid amplification of cDNA ends plus the polymerase chain reaction, we have cloned a full-length cDNA encoding a PMCA. In adult males, the PMCA transcript has been found in various tissues, including the antennae in which its presence has been detected in the sensilla trichodea, and in cultured ORNs. The PMCA gene is slightly expressed at the end of the pupal stage, reaches a maximum at emergence and is maintained at a high level during the adult period. Taken together, these results provide, for the first time, molecular evidence for the putative participation of a PMCA in signalling pathways responsible for the establishment and functioning of the insect peripheral olfactory system.
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282
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Klomp JA, Furge KA. Genome-wide matching of genes to cellular roles using guilt-by-association models derived from single sample analysis. BMC Res Notes 2012; 5:370. [PMID: 22824328 PMCID: PMC3599284 DOI: 10.1186/1756-0500-5-370] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 07/23/2012] [Indexed: 11/10/2022] Open
Abstract
Background High-throughput methods that ascribe a cellular or physiological function for each gene product are useful to understand the roles of genes that have not been extensively characterized by molecular or genetic approaches. One method to infer gene function is "guilt-by-association", in which the expression pattern of a poorly characterized gene is shown to co-vary with the expression of better-characterized genes. The function of the poorly characterized gene is inferred from the known function(s) of the well-described genes. For example, genes co-expressed with transcripts that vary during the cell cycle, development, environmental stresses, and with oncogenesis have been implicated in those processes. Findings While examining the expression characteristics of several poorly characterized genes, we noted that we could associate each of the genes with a cellular phenotype by correlating individual gene expression changes with gene set enrichment scores from individual samples. We evaluated the effectiveness of this approach using a modest sized gene expression data set (expO) and a compendium of gene expression phenotypes (MSigDBv3.0). We found the transcripts that correlated best with enrichment in mitochondrial and lysosomal gene sets were mostly related to those processes (89/100 and 44/50, respectively). The reciprocal evaluation, ranking gene sets according to correlation of enrichment with an individual gene’s expression, also reflected known associations for prominent genes in the biomedical literature (16/19). In evaluating the model, we also found that 4% of the genome encodes proteins that are associated with small molecule and small peptide signal transduction gene sets, implicating a large number of genes in both internal and external environmental sensing. Conclusions Our results show that this approach is useful to infer functions of disparate sets of genes. This method mirrors the biological experimental approaches used by others to associate individual genes with defined gene expression changes. Moreover, the approach can be used beyond discovering genes related to a cellular process to discover meaningful expression phenotypes from a compendium that are associated with a given gene. The effectiveness, versatility, and breadth of this approach make possible its application in a variety of contexts and with a variety of downstream analyses.
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Affiliation(s)
- Jeff A Klomp
- Center for Cancer Genomics and Computational Biology, Van Andel Research Institute, Grand Rapids, MI, USA
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283
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Global Transcriptional Analysis of Olfactory Genes in the Head of Pine Shoot Beetle, Tomicus yunnanensis. Comp Funct Genomics 2012; 2012:491748. [PMID: 22761546 PMCID: PMC3385610 DOI: 10.1155/2012/491748] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 04/02/2012] [Accepted: 04/26/2012] [Indexed: 11/30/2022] Open
Abstract
The most important proteins involved in olfaction include odorant binding protein (OBP), chemosensory protein (CSP), olfactory receptor (OR), and gustatory receptor (GR). Despite that the exhaustive genomic analysis has revealed a large number of olfactory genes in a number of model insects, it is still poorly understood for most nonmodel species. This is mostly due to the reason that the small antenna is challenging for collection. We can generally isolate one or few genes at a time by means of the traditional method. Here, we present the large-scale identifying members of the main olfactory genes from the head of Tomicus yunnanensis using Illumina sequencing. In a single run, we obtained over 51.8 million raw reads. These reads were assembled into 57,142 unigenes. Nearly 29,384 of them were functionally annotated in the NCBI nonredundant database. By depth analysis of the data, 11 OBPs, 8 CSPs, 18 ORs, and 8 GRs were retrieved. Sequences encoding full length proteins were further characterised for one OBP and two CSPs. The obtained olfactory genes provide a major resource in further unraveling the molecular mechanisms of T. yunnanensis chemoperception. This study indicates that the next generation sequencing is an attractive approach for efficient identification of olfactory genes from insects, for which the genome sequence is unavailable.
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284
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Fonollosa J, Gutierrez-Galvez A, Marco S. Quality coding by neural populations in the early olfactory pathway: analysis using information theory and lessons for artificial olfactory systems. PLoS One 2012; 7:e37809. [PMID: 22719851 PMCID: PMC3377695 DOI: 10.1371/journal.pone.0037809] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 04/23/2012] [Indexed: 01/08/2023] Open
Abstract
In this article, we analyze the ability of the early olfactory system to detect and discriminate different odors by means of information theory measurements applied to olfactory bulb activity images. We have studied the role that the diversity and number of receptor neuron types play in encoding chemical information. Our results show that the olfactory receptors of the biological system are low correlated and present good coverage of the input space. The coding capacity of ensembles of olfactory receptors with the same receptive range is maximized when the receptors cover half of the odor input space - a configuration that corresponds to receptors that are not particularly selective. However, the ensemble's performance slightly increases when mixing uncorrelated receptors of different receptive ranges. Our results confirm that the low correlation between sensors could be more significant than the sensor selectivity for general purpose chemo-sensory systems, whether these are biological or biomimetic.
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Affiliation(s)
- Jordi Fonollosa
- Department of Electronics, Universitat de Barcelona, Barcelona, Spain
- Artificial Olfaction Group, Institute for Bioengineering of Catalonia, Barcelona, Spain
| | - Agustin Gutierrez-Galvez
- Department of Electronics, Universitat de Barcelona, Barcelona, Spain
- Artificial Olfaction Group, Institute for Bioengineering of Catalonia, Barcelona, Spain
| | - Santiago Marco
- Department of Electronics, Universitat de Barcelona, Barcelona, Spain
- Artificial Olfaction Group, Institute for Bioengineering of Catalonia, Barcelona, Spain
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285
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Buck J, Levin LR. Physiological sensing of carbon dioxide/bicarbonate/pH via cyclic nucleotide signaling. SENSORS 2012; 11:2112-28. [PMID: 21544217 PMCID: PMC3085406 DOI: 10.3390/s110202112] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Carbon dioxide (CO2) is produced by living organisms as a byproduct of metabolism. In physiological systems, CO2 is unequivocally linked with bicarbonate (HCO3−) and pH via a ubiquitous family of carbonic anhydrases, and numerous biological processes are dependent upon a mechanism for sensing the level of CO2, HCO3, and/or pH. The discovery that soluble adenylyl cyclase (sAC) is directly regulated by bicarbonate provided a link between CO2/HCO3/pH chemosensing and signaling via the widely used second messenger cyclic AMP. This review summarizes the evidence that bicarbonate-regulated sAC, and additional, subsequently identified bicarbonate-regulate nucleotidyl cyclases, function as evolutionarily conserved CO2/HCO3/pH chemosensors in a wide variety of physiological systems.
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Affiliation(s)
- Jochen Buck
- Department of Pharmacology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10065, USA.
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286
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Ruan Y, Zheng XY, Zhang HL, Zhu W, Zhu J. Olfactory dysfunctions in neurodegenerative disorders. J Neurosci Res 2012; 90:1693-700. [DOI: 10.1002/jnr.23054] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/30/2012] [Accepted: 02/10/2012] [Indexed: 11/09/2022]
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287
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Aguilera LU, Galindo BE, Sánchez D, Santillán M. What is the core oscillator in the speract-activated pathway of the Strongylocentrotus purpuratus sperm flagellum? Biophys J 2012; 102:2481-8. [PMID: 22713563 DOI: 10.1016/j.bpj.2012.03.075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 03/06/2012] [Accepted: 03/29/2012] [Indexed: 12/31/2022] Open
Abstract
Sperm chemotaxis has an important role in fertilization. Most of our knowledge regarding this phenomenon comes from studies in organisms whose fertilization occurs externally, like sea urchins. Sea urchin spermatozoa respond to sperm-activating peptides, which diffuse from the egg jelly coat and interact with their receptor in the flagellum, triggering several physiological responses: changes in membrane potential, intracellular pH, cyclic nucleotide levels, and intracellular Ca2+ concentration ([Ca2+]). In particular, flagellar [Ca2+] has been shown to oscillate. These [Ca2+] oscillations are correlated with changes in the flagellar shape and so with the regulation of the sperm swimming paths. In this study, we demonstrate, from a mathematical modeling perspective, that the reported speract-activated signaling pathway in Strongylocentrotus purpuratus (speract being a sperm-activating peptide specific to this species) has the necessary elements to replicate the reported [Ca2+] oscillations. We further investigate which elements of this signaling pathway constitute the core oscillator.
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Affiliation(s)
- Luis U Aguilera
- Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Monterrey, Parque de Investigación e Innovación Tecnológica, Apodaca, Mexico
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288
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Identification of chemosensory receptor genes in Manduca sexta and knockdown by RNA interference. BMC Genomics 2012; 13:211. [PMID: 22646846 PMCID: PMC3464597 DOI: 10.1186/1471-2164-13-211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 03/30/2012] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Insects detect environmental chemicals via a large and rapidly evolving family of chemosensory receptor proteins. Although our understanding of the molecular genetic basis for Drosophila chemoreception has increased enormously in the last decade, similar understanding in other insects remains limited. The tobacco hornworm, Manduca sexta, has long been an important model for insect chemosensation, particularly from ecological, behavioral, and physiological standpoints. It is also a major agricultural pest on solanaceous crops. However, little sequence information and lack of genetic tools has prevented molecular genetic analysis in this species. The ability to connect molecular genetic mechanisms, including potential lineage-specific changes in chemosensory genes, to ecologically relevant behaviors and specializations in M. sexta would be greatly beneficial. RESULTS Here, we sequenced transcriptomes from adult and larval chemosensory tissues and identified chemosensory genes based on sequence homology. We also used dsRNA feeding as a method to induce RNA interference in larval chemosensory tissues. CONCLUSIONS We report identification of new chemosensory receptor genes including 17 novel odorant receptors and one novel gustatory receptor. Further, we demonstrate that systemic RNA interference can be used in larval olfactory neurons to reduce expression of chemosensory receptor transcripts. Together, our results further the development of M. sexta as a model for functional analysis of insect chemosensation.
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289
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Schwarting GA, Henion TR. Regulation and function of axon guidance and adhesion molecules during olfactory map formation. J Cell Biochem 2012; 112:2663-71. [PMID: 21618591 DOI: 10.1002/jcb.23203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The olfactory system presents a practical model for investigating basic mechanisms involved in patterning connections between peripheral sensory neurons and central targets. Our understanding of olfactory map formation was advanced greatly by the discovery of cAMP signaling as an important determinant of glomerular positioning in the olfactory bulb. Additionally, several cell adhesion molecules have been identified recently that are proposed to regulate homotypic interactions among projecting axons. From these studies a model has emerged to partially explain the wiring of axons from widely dispersed neuron populations in the nasal cavity to relatively stereotyped glomerular positions. These advances have revitalized interest in axon guidance molecules in establishing olfactory topography, but also open new questions regarding how these patterns of guidance cues are established and function, and what other pathways, such as glycosylation, might be involved. This review summarizes the current state of this field and the important molecules that impact on cAMP-dependent mechanism in olfactory axon guidance.
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Affiliation(s)
- Gerald A Schwarting
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
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290
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Immonen E, Ritchie MG. The genomic response to courtship song stimulation in female Drosophila melanogaster. Proc Biol Sci 2012; 279:1359-65. [PMID: 21976688 PMCID: PMC3282362 DOI: 10.1098/rspb.2011.1644] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/12/2011] [Indexed: 11/12/2022] Open
Abstract
Courtship behaviour involves a complex exchange of signals and responses. These are usually studied at the phenotypic level, and genetic or transcriptional responses to courtship are still poorly understood. Here, we examine the gene-expression changes in Drosophila melanogaster females in response to one of the key male courtship signals in mate recognition, song produced by male wing vibration. Using long oligonucleotide microarrays, we identified several genes that responded differentially to the presence or absence of acoustic courtship stimulus. These changes were modest in both the number of genes involved and fold-changes, but notably dominated by antennal signalling genes involved in olfaction as well as neuropeptides and immune response genes. Second, we compared the expression patterns of females stimulated with synthetic song typical of either conspecific or heterospecific (Drosophila simulans) males. In this case, antennal olfactory signalling and innate immunity genes were also enriched among the differentially expressed genes. We confirmed and investigated the time course of expression differences of two identified immunity genes using real-time quantitative PCR. Our results provide novel insight into specific molecular changes in females in response to courtship song stimulation. These may be involved in both signal perception and interpretation and some may anticipate molecular interactions that occur between the sexes after mating.
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Affiliation(s)
| | - Michael G. Ritchie
- Centre for Evolution, Genes and Genomics, School of Biology, Dyers Brae House, University of St Andrews, Fife KY16 9TH, UK
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291
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Ponissery Saidu S, Dibattista M, Matthews HR, Reisert J. Odorant-induced responses recorded from olfactory receptor neurons using the suction pipette technique. J Vis Exp 2012:e3862. [PMID: 22508037 DOI: 10.3791/3862] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Animals sample the odorous environment around them through the chemosensory systems located in the nasal cavity. Chemosensory signals affect complex behaviors such as food choice, predator, conspecific and mate recognition and other socially relevant cues. Olfactory receptor neurons (ORNs) are located in the dorsal part of the nasal cavity embedded in the olfactory epithelium. These bipolar neurons send an axon to the olfactory bulb (see Fig. 1, Reisert & Zhao, originally published in the Journal of General Physiology) and extend a single dendrite to the epithelial border from where cilia radiate into the mucus that covers the olfactory epithelium. The cilia contain the signal transduction machinery that ultimately leads to excitatory current influx through the ciliary transduction channels, a cyclic nucleotide-gated (CNG) channel and a Ca(2+)-activated Cl(-) channel (Fig. 1). The ensuing depolarization triggers action potential generation at the cell body. In this video we describe the use of the "suction pipette technique" to record odorant-induced responses from ORNs. This method was originally developed to record from rod photoreceptors and a variant of this method can be found at jove.com modified to record from mouse cone photoreceptors. The suction pipette technique was later adapted to also record from ORNs. Briefly, following dissociation of the olfactory epithelium and cell isolation, the entire cell body of an ORN is sucked into the tip of a recording pipette. The dendrite and the cilia remain exposed to the bath solution and thus accessible to solution changes to enable e.g. odorant or pharmacological blocker application. In this configuration, no access to the intracellular environment is gained (no whole-cell voltage clamp) and the intracellular voltage remains free to vary. This allows the simultaneous recording of the slow receptor current that originates at the cilia and fast action potentials fired by the cell body. The difference in kinetics between these two signals allows them to be separated using different filter settings. This technique can be used on any wild type or knockout mouse or to record selectively from ORNs that also express GFP to label specific subsets of ORNs, e.g. expressing a given odorant receptor or ion channel.
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292
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Odorant receptor modulation: Ternary paradigm for mode of action of insect repellents. Neuropharmacology 2012; 62:2086-95. [DOI: 10.1016/j.neuropharm.2012.01.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 12/12/2011] [Accepted: 01/09/2012] [Indexed: 11/18/2022]
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293
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Amino acid residues contributing to function of the heteromeric insect olfactory receptor complex. PLoS One 2012; 7:e32372. [PMID: 22403649 PMCID: PMC3293798 DOI: 10.1371/journal.pone.0032372] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 01/26/2012] [Indexed: 12/03/2022] Open
Abstract
Olfactory receptors (Ors) convert chemical signals—the binding of odors and pheromones—to electrical signals through the depolarization of olfactory sensory neurons. Vertebrates Ors are G-protein-coupled receptors, stimulated by odors to produce intracellular second messengers that gate ion channels. Insect Ors are a heteromultimeric complex of unknown stoichiometry of two seven transmembrane domain proteins with no sequence similarity to and the opposite membrane topology of G-protein-coupled receptors. The functional insect Or comprises an odor- or pheromone-specific Or subunit and the Orco co-receptor, which is highly conserved in all insect species. The insect Or-Orco complex has been proposed to function as a novel type of ligand-gated nonselective cation channel possibly modulated by G-proteins. However, the Or-Orco proteins lack homology to any known family of ion channel and lack known functional domains. Therefore, the mechanisms by which odors activate the Or-Orco complex and how ions permeate this complex remain unknown. To begin to address the relationship between Or-Orco structure and function, we performed site-directed mutagenesis of all 83 conserved Glu, Asp, or Tyr residues in the silkmoth BmOr-1-Orco pheromone receptor complex and measured functional properties of mutant channels expressed in Xenopus oocytes. 13 of 83 mutations in BmOr-1 and BmOrco altered the reversal potential and rectification index of the BmOr-1-Orco complex. Three of the 13 amino acids (D299 and E356 in BmOr-1 and Y464 in BmOrco) altered both current-voltage relationships and K+ selectivity. We introduced the homologous Orco Y464 residue into Drosophila Orco in vivo, and observed variable effects on spontaneous and evoked action potentials in olfactory neurons that depended on the particular Or-Orco complex examined. Our results provide evidence that a subset of conserved Glu, Asp and Tyr residues in both subunits are essential for channel activity of the heteromeric insect Or-Orco complex.
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294
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The CatSper channel: a polymodal chemosensor in human sperm. EMBO J 2012; 31:1654-65. [PMID: 22354039 DOI: 10.1038/emboj.2012.30] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 01/18/2012] [Indexed: 01/10/2023] Open
Abstract
The sperm-specific CatSper channel controls the intracellular Ca(2+) concentration ([Ca(2+)](i)) and, thereby, the swimming behaviour of sperm. In humans, CatSper is directly activated by progesterone and prostaglandins-female factors that stimulate Ca(2+) influx. Other factors including neurotransmitters, chemokines, and odorants also affect sperm function by changing [Ca(2+)](i). Several ligands, notably odorants, have been proposed to control Ca(2+) entry and motility via G protein-coupled receptors (GPCRs) and cAMP-signalling pathways. Here, we show that odorants directly activate CatSper without involving GPCRs and cAMP. Moreover, membrane-permeable analogues of cyclic nucleotides that have been frequently used to study cAMP-mediated Ca(2+) signalling also activate CatSper directly via an extracellular site. Thus, CatSper or associated protein(s) harbour promiscuous binding sites that can host various ligands. These results contest current concepts of Ca(2+) signalling by GPCR and cAMP in mammalian sperm: ligands thought to activate metabotropic pathways, in fact, act via a common ionotropic mechanism. We propose that the CatSper channel complex serves as a polymodal sensor for multiple chemical cues that assist sperm during their voyage across the female genital tract.
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295
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Rebora M, Salerno G, Piersanti S, Dell'otto A, Gaino E. Olfaction in dragonflies: electrophysiological evidence. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:270-277. [PMID: 22154954 DOI: 10.1016/j.jinsphys.2011.11.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 11/24/2011] [Accepted: 11/28/2011] [Indexed: 05/31/2023]
Abstract
The problem of olfaction in Paleoptera (Odonata, Ephemeroptera) cannot be considered fully elucidated until now. These insects have been traditionally considered anosmic, because their brain lacks glomerular antennal lobes, typically involved in Neoptera odor perception. In order to understand if the presumed coeloconic olfactory receptors described on the antennal flagellum of adult Odonata are really functioning, we performed an electrophysiological investigation with electroantennogram (EAG) and single cell recordings (SCR), using Libellula depressa L. (Odonata, Libellulidae) as a model species. Odors representing different chemical classes such as (Z)-3-hexenyl acetate (acetate ester), (E)-2-hexenal, octanal (aldehydes), (Z)-3-hexen-1-ol (alcohol), propionic acid, butyric acid (carboxylic acids), and 1,4-diaminobutane (amine) were tested. Most of the tested chemicals elicited depolarizing EAG responses in both male and female antennae; SCR show unambiguously for the first time the presence of olfactory neurons in the antennae of L. depressa and strongly support the olfactory function of the coeloconic sensilla located on the antennal flagellum of this species. Electrophysiological activity may not necessarily indicate behavioral activity, and the biological role of olfactory responses in Odonata must be determined in behavioral bioassays. This study represents a starting point for further behavioral, electrophysiological, neuroanatomical and molecular investigation on Odonata olfaction, a research field particularly interesting owing to the basal position of Paleoptera, also for tracing evolutionary trends in insect olfaction.
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Affiliation(s)
- Manuela Rebora
- Dipartimento di Biologia Cellulare e Ambientale, Via Elce di Sotto, 06123 Perugia, Italy.
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296
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Jones PL, Pask GM, Romaine IM, Taylor RW, Reid PR, Waterson AG, Sulikowski GA, Zwiebel LJ. Allosteric antagonism of insect odorant receptor ion channels. PLoS One 2012; 7:e30304. [PMID: 22272331 PMCID: PMC3260273 DOI: 10.1371/journal.pone.0030304] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 12/13/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND At a molecular level, insects utilize members of several highly divergent and unrelated families of cell-surface chemosensory receptors for detection of volatile odorants. Most odors are detected via a family of odorant receptors (ORs), which form heteromeric complexes consisting of a well-conserved OR co-receptor (Orco) ion channel and a non-conserved tuning OR that provides coding specificity to each complex. Orco functions as a non-selective cation channel and is expressed in the majority of olfactory receptor neurons (ORNs). As the destructive behaviors of many insects are principally driven by olfaction, Orco represents a novel target for behavior-based control strategies. While many natural and synthetic odorants have been shown to agonize Orco/Or complexes, only a single direct Orco modulator, VUAA1, has been described. In an effort to identify additional Orco modulators, we have investigated the structure/activity relationships around VUAA1. RESULTS A search of our compound library identified several VUAA1 analogs that were selected for evaluation against HEK cells expressing Orco from the malaria vector Anopheles gambiae (AgOrco). While the majority of compounds displayed no activity, many of these analogs possess no intrinsic efficacy, but instead, act as competitive VUAA1 antagonists. Using calcium mobilization assays, patch clamp electrophysiology, and single sensillum in vivo recording, we demonstrate that one such candidate, VU0183254, is a specific allosteric modulator of OR signaling, capable of broadly inhibiting odor-mediated OR complex activation. CONCLUSIONS We have described and characterized the first Orco antagonist, that is capable of non-competitively inhibiting odorant-evoked activation of OR complexes, thereby providing additional insight into the structure/function of this unique family of ligand-gated ion channels. While Orco antagonists are likely to have limited utility in insect control programs, they represent important pharmacological tools that will facilitate the investigation of the molecular mechanisms underlying insect olfactory signal transduction.
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Affiliation(s)
- Patrick L. Jones
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Gregory M. Pask
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ian M. Romaine
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Robert W. Taylor
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Paul R. Reid
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Alex G. Waterson
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Gary A. Sulikowski
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Laurence J. Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Center for Molecular Neuroscience, Institute of Global Health and Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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Konno A, Setou M, Ikegami K. Ciliary and flagellar structure and function--their regulations by posttranslational modifications of axonemal tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 294:133-70. [PMID: 22364873 DOI: 10.1016/b978-0-12-394305-7.00003-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Eukaryotic cilia and flagella are evolutionarily conserved microtubule-based organelles protruding from the cell surface. They perform dynein-driven beating which contributes to cell locomotion or flow generation. They also play important roles in sensing as cellular antennae, which allows cells to respond to various external stimuli. The main components of cilia and flagella, α- and β-tubulins, are known to undergo various posttranslational modifications (PTMs), including phosphorylation, palmitoylation, tyrosination/detyrosination, Δ2 modification, acetylation, glutamylation, and glycylation. Recent identification of tubulin-modifying enzymes, especially tubulin tyrosine ligase-like proteins which perform tubulin glutamylation and glycylation, has demonstrated the importance of tubulin modifications for the assembly and functions of cilia and flagella. In this chapter, we review recent work on PTMs of ciliary and flagellar tubulins in conjunction with discussing the basic knowledge.
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Affiliation(s)
- Alu Konno
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
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298
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Bohbot JD, Fu L, LE TC, Chauhan KR, Cantrell CL, Dickens JC. Multiple activities of insect repellents on odorant receptors in mosquitoes. MEDICAL AND VETERINARY ENTOMOLOGY 2011; 25:436-444. [PMID: 21395633 DOI: 10.1111/j.1365-2915.2011.00949.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Several lines of evidence suggest that insect repellent molecules reduce mosquito-host contacts by interacting with odorants and odorant receptors (ORs), thereby ultimately affecting olfactory-driven behaviours. We describe the molecular effects of 10 insect repellents and a pyrethroid insecticide with known repellent activity on two highly specific Aedes aegypti (Diptera: Culicidae) ORs, AaOR2 + AaOR7 and AaOR8 + AaOR7, exquisitely sensitive to key mosquito attractants indole and (R)-(-)-1-octen-3-ol, expressed in oocytes of Xenopus (Anura: Pipidae). Our study demonstrates that insect repellents can both inhibit odorant-evoked currents mediated by ORs and independently elicit currents in the absence of odorants. All of the repellents had effects on one or both ORs; most of these compounds were selective inhibitors and showed a high degree of specificity in their capacity to activate the two ORs. These results show that a range of insect repellents belonging to structurally diverse chemical classes modulate the function of mosquito ORs through multiple molecular mechanisms.
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Affiliation(s)
- J D Bohbot
- Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD, U.S.A.
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The Na(+)/Ca(2+) exchanger NCKX4 governs termination and adaptation of the mammalian olfactory response. Nat Neurosci 2011; 15:131-7. [PMID: 22057188 PMCID: PMC3245797 DOI: 10.1038/nn.2943] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 08/29/2011] [Indexed: 11/09/2022]
Abstract
Sensory perception requires accurate encoding of stimulus information by sensory receptor cells. We identified NCKX4, a potassium-dependent Na(+)/Ca(2+) exchanger, as being necessary for rapid response termination and proper adaptation of vertebrate olfactory sensory neurons (OSNs). Nckx4(-/-) (also known as Slc24a4) mouse OSNs displayed substantially prolonged responses and stronger adaptation. Single-cell electrophysiological analyses revealed that the majority of Na(+)-dependent Ca(2+) exchange in OSNs relevant to sensory transduction is a result of NCKX4 and that Nckx4(-/-) mouse OSNs are deficient in encoding action potentials on repeated stimulation. Olfactory-specific Nckx4(-/-) mice had lower body weights and a reduced ability to locate an odorous source. These results establish the role of NCKX4 in shaping olfactory responses and suggest that rapid response termination and proper adaptation of peripheral sensory receptor cells tune the sensory system for optimal perception.
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Olsen CA, Kristensen AS, Strømgaard K. Niedermolekulare Verbindungen aus Spinnen als chemische Sensoren. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201101599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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