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Ma Y, Yang TT, Ni S, Wang JX, He Y, Si YX, Zhang J, Dong SL, Yan Q. The Odorant Receptor Recognizing Camphor in a Camphor Tree Specialist Orthaga achatina (Lepidoptera: Pyralidae). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:2689-2696. [PMID: 38267394 DOI: 10.1021/acs.jafc.3c08877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
Camphor has been used as an effective repellent and pesticide to stored products for a long history, but Orthaga achatina (Lepidoptera: Pyralidae) has evolved to specifically feed on the camphor tree Cinnamomum camphora. However, the behavioral response of O. achatina to camphor and the molecular basis of camphor perception are totally unknown. Here, we demonstrated that both male and female adults were behaviorally attracted to camphor, suggesting the adaptation of O. achatina to and utilization of camphor as a signal of C. camphora. Second, in 40 O. achatina OR genes obtained by analyzing antenna transcriptomes, only OachOR16/Orco significantly responded to camphor in the Xenopus oocyte system. Finally, by molecular docking analysis and site-directed mutagenesis, the Ser209 residue is confirmed to be essential for binding of the oachOR16 with camphor. This study not only reveals the camphor-based host plant choice and olfactory mechanisms of O. achatina but also provides a molecular target for screening more potential insect repellents.
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Affiliation(s)
- Yu Ma
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Ting-Ting Yang
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuang Ni
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Ji-Xiang Wang
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu He
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu-Xiao Si
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Jin Zhang
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuang-Lin Dong
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Qi Yan
- Key Laboratory of Integrated Management of Crop Disease and Pests, Ministry of Education/College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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Pacalon J, Audic G, Magnat J, Philip M, Golebiowski J, Moreau CJ, Topin J. Elucidation of the structural basis for ligand binding and translocation in conserved insect odorant receptor co-receptors. Nat Commun 2023; 14:8182. [PMID: 38081900 PMCID: PMC10713630 DOI: 10.1038/s41467-023-44058-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
In numerous insects, the olfactory receptor family forms a unique class of heteromeric cation channels. Recent progress in resolving the odorant receptor structures offers unprecedented opportunities for deciphering their molecular mechanisms of ligand recognition. Unexpectedly, these structures in apo or ligand-bound states did not reveal the pathway taken by the ligands between the extracellular space and the deep internal cavities. By combining molecular modeling with electrophysiological recordings, we identified amino acids involved in the dynamic entry pathway and the binding of VUAA1 to Drosophila melanogaster's odorant receptor co-receptor (Orco). Our results provide evidence for the exact location of the agonist binding site and a detailed and original mechanism of ligand translocation controlled by a network of conserved residues. These findings would explain the particularly high selectivity of Orcos for their ligands.
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Affiliation(s)
- Jody Pacalon
- Université Côte d'Azur, Institut de Chimie de Nice UMR7272, CNRS, Nice, France
| | | | | | - Manon Philip
- Univ. Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Jérôme Golebiowski
- Department of Brain & Cognitive Sciences, DGIST, 333, Techno JungAng, Daero, HyeongPoong Myeon, Daegu, Republic of Korea
| | | | - Jérémie Topin
- Université Côte d'Azur, Institut de Chimie de Nice UMR7272, CNRS, Nice, France.
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Ning X, Huang C, Dong C, Jin J, Qiao X, Guo J, Qian W, Cao F, Wan F. RNAi verifications on olfactory defects of an essential biocontrol agent Agasicles hygrophila (Coleoptera: Chrysomelidae) regarding mating and host allocation. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1104962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Alligator weed Alternanthera philoxeroides is a perennial, worldwide pernicious weed. The beetle Agasicles hygrophila is considered to be a classical biological agent used to control A. philoxeroides. In the insect peripheral olfactory system, the odorant receptor co-receptor (ORco) plays an important function in the perception of odors in insects. However, the function of ORco in the mating and host-finding behaviors of A. hygrophila remains unclear. In this study, we characterized the odorant receptor co-receptor of A. hygrophila (AhygOrco). Real-time quantitative PCR (qRT–PCR) showed that AhygOrco was predominantly expressed in the antennae of both male and female adults, and the difference between male and female antennae was not significant. The RNA interference (RNAi) results showed that compared to the control, the injection of AhygOrco dsRNA strongly reduced the expression of AhygOrco by 90% in male beetles and 89% in female beetles. The mate-seeking and feeding behavior of AhygOrco-silenced beetles were significantly inhibited. Male adults were significantly less successful in finding a mate compared to the control group. Furthermore, host allocation abilities toward A. philoxeroides of both adults were significantly repressed. These results indicated that AhygOrco is associated with A. hygrophila feeding and mate-seeking and that inhibition of AhygOrco expression is one of the causes of reduced host and mate recognition in A. hygrophila. Meanwhile, the study provides support for exploring gene functions based on RNAi.
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Silencing the odorant receptor co-receptor impairs olfactory reception in a sensillum-specific manner in the cockroach. iScience 2022; 25:104272. [PMID: 35521537 PMCID: PMC9065313 DOI: 10.1016/j.isci.2022.104272] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 03/16/2022] [Accepted: 04/13/2022] [Indexed: 11/20/2022] Open
Abstract
Insects detect odors via a large variety of odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs). The insect OR is a heteromeric complex composed of a ligand-specific receptor and the co-receptor (ORco). In this study, we identified the ORco gene of the cockroach, Periplaneta americana (PameORco), and performed RNAi-based functional analysis of PameORco. All OSNs in the basiconic sensilla expressed PameORco and received a large variety of odors including sex pheromones. In trichoid sensilla, a PameORco-positive OSN was consistently paired with a PameORco-negative OSN tuned to acids. In adult cockroaches injected with PameORco dsRNA at the nymphal stage, the expression of PameORco, odor receptions via ORs, and its central processing were strongly suppressed. These results provide new insights into the molecular basis of olfactory reception in the cockroach. The long-lasting and irreversible effects of PameORco RNAi would be an effective method for controlling the household pest. Whole sequence of ORco in the American cockroach (PameORco) was characterized PameORco expressed in olfactory sensory neurons in a sensillar type-specific manner RNAi chronically and irreversibly suppressed the PameORco expression beyond molts PameORco was essential for receptions of sex pheromones and general odors
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Sims C, Birkett MA, Withall DM. Enantiomeric Discrimination in Insects: The Role of OBPs and ORs. INSECTS 2022; 13:insects13040368. [PMID: 35447810 PMCID: PMC9030700 DOI: 10.3390/insects13040368] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/25/2022] [Accepted: 03/30/2022] [Indexed: 01/27/2023]
Abstract
Olfaction is a complex recognition process that is critical for chemical communication in insects. Though some insect species are capable of discrimination between compounds that are structurally similar, little is understood about how this high level of discrimination arises. Some insects rely on discriminating between enantiomers of a compound, demonstrating an ability for highly selective recognition. The role of two major peripheral olfactory proteins in insect olfaction, i.e., odorant-binding proteins (OBPs) and odorant receptors (ORs) has been extensively studied. OBPs and ORs have variable discrimination capabilities, with some found to display highly specialized binding capability, whilst others exhibit promiscuous binding activity. A deeper understanding of how odorant-protein interactions induce a response in an insect relies on further analysis such as structural studies. In this review, we explore the potential role of OBPs and ORs in highly specific recognition, specifically enantiomeric discrimination. We summarize the state of research into OBP and OR function and focus on reported examples in the literature of clear enantiomeric discrimination by these proteins.
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Affiliation(s)
- Cassie Sims
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK; (C.S.); (M.A.B.)
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Michael A. Birkett
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK; (C.S.); (M.A.B.)
| | - David M. Withall
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK; (C.S.); (M.A.B.)
- Correspondence: ; Tel.: +44-(0)-1582-938201
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Guo L, Xu B, Zhao H, Guo Y, Jiang Y. Calmodulin Activity Affects the Function of the Odorant Receptor AcerOr2 in Honeybees. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.848150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Bees rely on their sensitive olfactory system to perform foraging activities in the surrounding environment. This ability is associated with the existence of olfactory receptors (ORs). In this study, we identified the AcerOr2 (ortholog to the Orco) protein in Apis cerana cerana, which contains a conserved, putative calmodulin (CaM)-binding site (CBS) indicating that CaM is involved in its function. We used immunofluorescence, Western blot, and Ca2 + imaging to monitor changes in the expression and activation of the signaling pathway associated with Ca2 + and Ca2 +/CaM-dependent protein kinase II (CaMKII) in Sf9 cells heterologously expressing AcerOr2 and a CaM-binding mutant. We used the synthetic Orco agonist VUAA1 to stimulate the cells or the antagonist W7 to inhibit CaM activity. The AcerOr2 CaM-binding mutant has a point mutation in the putative CBS (K331N). When heterologously expressed in Sf9 cells, the mutant should have less CaM activity. When the cells expressing AcerOr2 were treated with W7, the Ca2 + response of AceOr2 was similar to that of the mutant stimulated by VUAA1, and the expression of the CaM, CaMKII, and p-CaMKII has similar effects. Our results suggest that CaM activity affects the function of AceOr2 in vitro and can be used to further study the interaction between the AcerOr2 and calcium/CaM signaling pathway in the pollen collection behavior of bees.
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Xie J, Liu T, Yi C, Liu X, Tang H, Sun Y, Shi W, Khashaveh A, Zhang Y. Antenna-Biased Odorant Receptor HvarOR25 in Hippodamia variegata Tuned to Allelochemicals from Hosts and Habitat Involved in Perceiving Preys. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:1090-1100. [PMID: 35072468 DOI: 10.1021/acs.jafc.1c05593] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Odorant receptors (ORs) of ladybird Hippodamia variegata play vital chemosensory roles in searching and locating preys. In the current study, 37 ORs were initially identified from the antennal transcriptome of H. variegata. The quantitative polymerase chain reaction demonstrated that several HvarORs including HvarOR25 were specific or enriched in ladybird antennae. In two-electrode voltage clamp recordings, recombinant HvarOR25 was narrowly tuned to six chemical ligands including aphid-induced, aphid-derived, and plant-derived volatiles. In electroantennogram assays, all six volatiles elicited electrophysiological responses. Among the six volatiles, cis-3-hexenyl acetate, hexyl butyrate, hexyl hexanoate, and 3-methyl-3-buten-1-ol were attractive for both sexes of H. variegata. Additionally, molecular docking indicated that HvarOR25 was bound to all ligands with high binding affinities. Taken together, HvarOR25 facilitates perception of preys by recognizing relevant allelochemicals from hosts and habitat. Our findings provide valuable insights into understanding biological functions of HvarORs and help to develop a novel biocontrol strategy based on olfactory-active compounds.
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Affiliation(s)
- Jiaoxin Xie
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- Department of Entomology, China Agricultural University, Beijing 100193, China
| | - Tinghui Liu
- College of Plant Protection, Hebei Agricultural University, Baoding 071001, China
| | - Chaoqun Yi
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- College of Plant Protection, Hebei Agricultural University, Baoding 071001, China
| | - Xiaoxu Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- College of Plant Protection, Hebei Agricultural University, Baoding 071001, China
| | - Haoyu Tang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu 241000, China
| | - Yang Sun
- Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu 241000, China
| | - Wangpeng Shi
- Department of Entomology, China Agricultural University, Beijing 100193, China
| | - Adel Khashaveh
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Yongjun Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Bobkov YV, Walker Iii WB, Cattaneo AM. Altered functional properties of the codling moth Orco mutagenized in the intracellular loop-3. Sci Rep 2021; 11:3893. [PMID: 33594162 PMCID: PMC7887336 DOI: 10.1038/s41598-021-83024-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 01/27/2021] [Indexed: 12/04/2022] Open
Abstract
Amino acid substitutions within the conserved polypeptide sequence of the insect olfactory receptor co-receptor (Orco) have been demonstrated to influence its pharmacological properties. By sequence analysis and phylogenetic investigation, in the Lepidopteran subgroup Ditrysia we identified a fixed substitution in the intracellular loop-3 (ICL-3) of a conserved histidine to glutamine. By means of HEK293 cells as a heterologous system, we functionally expressed Orco from the Ditrysian model Cydia pomonella (CpomOrco) and compared its functional properties with a site-directed mutagenized version where this ICL-3-glutamine was reverted to histidine (CpomOrcoQ417H). The mutagenized CpomOrcoQ417H displayed decreased responsiveness to VUAA1 and reduced response efficacy to an odorant agonist was observed, when co-transfected with the respective OR subunit. Evidence of reduced responsiveness and sensitivity to ligands for the mutagenized Orco suggest the fixed glutamine substitution to be optimized for functionality of the cation channel within Ditrysia. In addition, contrary to the wild type, the mutagenized CpomOrcoQ417H preserved characteristics of VUAA-binding when physiologic conditions turned to acidic. Taken together, our findings provide further evidence of the importance of ICL-3 in forming basic functional properties of insect Orco- and Orco/OR-channels, and suggest involvement of ICL-3 in the potential functional adaptation of Ditrysian Orcos to acidified extra-/intracellular environment.
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Affiliation(s)
- Yuriy V Bobkov
- Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL, USA
| | - William B Walker Iii
- Department of Plant Protection Biology, Chemical Ecology Unit, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Alberto Maria Cattaneo
- Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL, USA. .,Department of Plant Protection Biology, Chemical Ecology Unit, Swedish University of Agricultural Sciences, Alnarp, Sweden.
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Khashaveh A, An X, Shan S, Xiao Y, Wang Q, Wang S, Li Z, Geng T, Gu S, Zhang Y. Deorphanization of an odorant receptor revealed new bioactive components for green mirid bug Apolygus lucorum (Hemiptera: Miridae). PEST MANAGEMENT SCIENCE 2020; 76:1626-1638. [PMID: 31714013 DOI: 10.1002/ps.5682] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 10/30/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND The Apolygus lucorum is one of the most destructive insect pests in China with a wide range of host plants. Interaction of A. lucorum with surrounding environment heavily relies on chemical communication. Deorphanization of receptors involved in odors detection elevates our understanding of the olfactory system of this pest and may help to develop a chemical ecology-based control strategy. RESULTS AlucOR80, an odorant receptor (OR) in A. lucorum was newly cloned. Gene expression analysis showed that this receptor was mainly expressed in the antennae and head of both sexes but with a male bias. The Xenopus oocytes heterologous expression system coupled with the two-electrode voltage-clamp (TEVC) recording revealed that AlucOR80 was tuned to 21 selected compounds. Furthermore, electroantennogram (EAG) tests confirmed that all 21 ligands of AlucOR80 were electrophysiologically active in antennae of both sexes. Behavioral trials in a three-cage olfactometer indicated that 16 compounds were behaviorally active, amongst which, 12 components were attractants and four components were repellents for adults of both sexes. Butyl butyrate and Dimethyl disulfide (DMDS) were the strongest attractive and repellant compounds, respectively. Importantly, we found the repellency of 1, 8-Cineole, S-(-)-cis-Verbenol and (1S)-(1)-beta-Pinene against adults of A. lucorum. CONCLUSION Although AlucOR80 is a general OR, may play important role in the olfactory perception of A. lucorum. Screening of AlucOR80 ligands by behavioral assay provided valuable insights by which olfactory-based management approaches could be developed by utilizing the behaviorally active components as attractants or repellents. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Adel Khashaveh
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xingkui An
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shuang Shan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- College of Plant Protection, China Agricultural University, Beijing, China
| | - Yong Xiao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Qi Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shanning Wang
- Institute of Plant and Environment Protection, Beijing Academy of Agricultural and Forestry Sciences, Beijing, China
| | - Zibo Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ting Geng
- Langfang Scientific Research Trial Station, Chinese Academy of Agricultural Sciences, Langfang, China
| | - Shaohua Gu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yongjun Zhang
- 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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Khadka R, Carraher C, Hamiaux C, Travas-Sejdic J, Kralicek A. Synergistic improvement in the performance of insect odorant receptor based biosensors in the presence of Orco. Biosens Bioelectron 2020; 153:112040. [DOI: 10.1016/j.bios.2020.112040] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/23/2019] [Accepted: 01/20/2020] [Indexed: 11/30/2022]
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11
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Bui M, Shyong J, Lutz EK, Yang T, Li M, Truong K, Arvidson R, Buchman A, Riffell JA, Akbari OS. Live calcium imaging of Aedes aegypti neuronal tissues reveals differential importance of chemosensory systems for life-history-specific foraging strategies. BMC Neurosci 2019; 20:27. [PMID: 31208328 PMCID: PMC6580577 DOI: 10.1186/s12868-019-0511-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 06/10/2019] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The mosquito Aedes aegypti has a wide variety of sensory pathways that have supported its success as a species as well as a highly competent vector of numerous debilitating infectious pathogens. Investigations into mosquito sensory systems and their effects on behavior are valuable resources for the advancement of mosquito control strategies. Numerous studies have elucidated key aspects of mosquito sensory systems, however there remains critical gaps within the field. In particular, compared to that of the adult form, there has been a lack of studies directed towards the immature life stages. Additionally, although numerous studies have pinpointed specific sensory receptors as well as responding motor outputs, there has been a lack of studies able to monitor both concurrently. RESULTS To begin filling aforementioned gaps, here we engineered Ae. aegypti to ubiquitously express a genetically encoded calcium indicator, GCaMP6s. Using this strain, combined with advanced microscopy, we simultaneously measured live stimulus-evoked calcium responses in both neuronal and muscle cells with a wide spatial range and resolution. CONCLUSIONS By coupling in vivo live calcium imaging with behavioral assays we were able to gain functional insights into how stimulus-evoked neural and muscle activities are represented, modulated, and transformed in mosquito larvae enabling us to elucidate mosquito sensorimotor properties important for life-history-specific foraging strategies.
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Affiliation(s)
- Michelle Bui
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093 USA
| | - Jennifer Shyong
- Department of Entomology and Riverside Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521 USA
| | - Eleanor K. Lutz
- Department of Biology, University of Washington, Seattle, WA 98195 USA
| | - Ting Yang
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093 USA
| | - Ming Li
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093 USA
| | - Kenneth Truong
- Department of Entomology and Riverside Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521 USA
| | - Ryan Arvidson
- Department of Entomology and Riverside Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521 USA
| | - Anna Buchman
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093 USA
| | | | - Omar S. Akbari
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093 USA
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093 USA
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Gomez-Diaz C, Martin F, Garcia-Fernandez JM, Alcorta E. The Two Main Olfactory Receptor Families in Drosophila, ORs and IRs: A Comparative Approach. Front Cell Neurosci 2018; 12:253. [PMID: 30214396 PMCID: PMC6125307 DOI: 10.3389/fncel.2018.00253] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/23/2018] [Indexed: 12/20/2022] Open
Abstract
Most insect species rely on the detection of olfactory cues for critical behaviors for the survival of the species, e.g., finding food, suitable mates and appropriate egg-laying sites. Although insects show a diverse array of molecular receptors dedicated to the detection of sensory cues, two main types of molecular receptors have been described as responsible for olfactory reception in Drosophila, the odorant receptors (ORs) and the ionotropic receptors (IRs). Although both receptor families share the role of being the first chemosensors in the insect olfactory system, they show distinct evolutionary origins and several distinct structural and functional characteristics. While ORs are seven-transmembrane-domain receptor proteins, IRs are related to the ionotropic glutamate receptor (iGluR) family. Both types of receptors are expressed on the olfactory sensory neurons (OSNs) of the main olfactory organ, the antenna, but they are housed in different types of sensilla, IRs in coeloconic sensilla and ORs in basiconic and trichoid sensilla. More importantly, from the functional point of view, they display different odorant specificity profiles. Research advances in the last decade have improved our understanding of the molecular basis, evolution and functional roles of these two families, but there are still controversies and unsolved key questions that remain to be answered. Here, we present an updated review on the advances of the genetic basis, evolution, structure, functional response and regulation of both types of chemosensory receptors. We use a comparative approach to highlight the similarities and differences among them. Moreover, we will discuss major open questions in the field of olfactory reception in insects. A comprehensive analysis of the structural and functional convergence and divergence of both types of receptors will help in elucidating the molecular basis of the function and regulation of chemoreception in insects.
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Affiliation(s)
- Carolina Gomez-Diaz
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
| | - Fernando Martin
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
| | | | - Esther Alcorta
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
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Cattaneo AM. Current Status on the Functional Characterization of Chemosensory Receptors of Cydia pomonella (Lepidoptera: Tortricidae). Front Behav Neurosci 2018; 12:189. [PMID: 30210318 PMCID: PMC6120436 DOI: 10.3389/fnbeh.2018.00189] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/06/2018] [Indexed: 11/13/2022] Open
Abstract
Cydia pomonella (Lepidoptera: Tortricidae) is a major pest of apple, pear and walnuts. For its control, alternative strategies targeting the olfactory system, like mating disruption, have been combined with insecticide applications. The efficacy of these strategies headed the direction of efforts for the functional characterization of codling moth chemosensory receptors to implement further control methods based on chemical sensing. With the advent of transcriptomic analysis, partial and full-length coding sequences of chemosensory receptors have been identified in antennal transcriptomes of C. pomonella. Extension of partial coding sequences to full-length by polymerase chain reaction (PCR)-based techniques and heterologous expression in empty neurons of Drosophila melanogaster and in Human Embryonic Kidney cells allowed functional studies to investigate receptor activation and ligand binding modalities (deorphanization). Among different classes of antennal receptors, several odorant receptors of C. pomonella (CpomORs) have been characterized as binding kairomones (CpomOR3), pheromones (CpomOR6a) and compounds emitted by non-host plants (CpomOR19). Physiological and pharmacological studies of these receptors demonstrated their ionotropic properties, by forming functional channels with the co-receptor subunit of CpomOrco. Further investigations reported a novel insect transient receptor potential (TRPA5) expressed in antennae and other body parts of C. pomonella as a complex pattern of ribonucleic acid (RNA) splice-forms, with a possible involvement in sensing chemical stimuli and temperature. Investigation on chemosensory mechanisms in the codling moth has practical outcomes for the development of control strategies and it inspired novel trends to control this pest by integrating alternative methods to interfere with insect chemosensory communication.
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Affiliation(s)
- Alberto Maria Cattaneo
- Division of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
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Moore EL, Scott MA, Rodriguez SD, Mitra S, Vulcan J, Cordova JJ, Chung HN, Linhares Lino de Souza D, Gonzales KK, Hansen IA. An online survey of personal mosquito-repellent strategies. PeerJ 2018; 6:e5151. [PMID: 30002979 PMCID: PMC6034598 DOI: 10.7717/peerj.5151] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/12/2018] [Indexed: 12/21/2022] Open
Abstract
Background Mosquito repellents can be an effective method for personal protection against mosquito bites that are a nuisance and carry the risk of transmission of mosquito-borne pathogens like plasmodia, dengue virus, chikungunya virus, and Zika virus. A multitude of commercially available products are currently on the market, some of them highly effective while others have low or no efficacy. Many home remedies of unknown efficacy are also widely used. Methods We conducted a survey study to determine what kind of mosquito repellents and other mosquito control strategies people use. Our online survey was focused on unconventional methods and was answered by 5,209 participants. Results The majority of participants resided in the United States, were female (67%), had higher education (81% had a university degree), and were 18 to 37 years old (50%). The most commonly used repellent was DEET spray (48%), followed closely by citronella candles (43%) and ‘natural’ repellent sprays (36%). We collected a plethora of home remedies and other strategies people use that warrant further research into their effectiveness. Discussion Our study lays the foundation for future research in alternative, unconventional methods to repel mosquitoes that may be culturally acceptable and accessible for people.
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Affiliation(s)
- Emily Lucille Moore
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | - Mary Alice Scott
- Department of Anthropology, New Mexico State University, Las Cruces, NM, United States of America
| | - Stacy Deadra Rodriguez
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | - Soumi Mitra
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | - Julia Vulcan
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | - Joel Javierla Cordova
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | - Hae-Na Chung
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | | | - Kristina Kay Gonzales
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America
| | - Immo Alex Hansen
- Department of Biology, New Mexico State University, Las Cruces, NM, United States of America.,Institute for Applied Biosciences, New Mexico State University, Las Cruces, NM, United States of America
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Wang Q, Wang Q, Zhou YL, Shan S, Cui HH, Xiao Y, Dong K, Khashaveh A, Sun L, Zhang YJ. Characterization and Comparative Analysis of Olfactory Receptor Co-Receptor Orco Orthologs Among Five Mirid Bug Species. Front Physiol 2018; 9:158. [PMID: 29556202 PMCID: PMC5845112 DOI: 10.3389/fphys.2018.00158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/16/2018] [Indexed: 01/08/2023] Open
Abstract
The phytophagous mirid bugs of Apolygus lucorum, Lygus pratensis as well as three Adelphocoris spp., including Adelphocoris lineolatus, A. suturalis, and A. fasciaticollis are major pests of multiple agricultural crops in China, which have distinct geographical distribution and occurrence ranges. Like many insect species, these bugs heavily rely on olfactory cues to search preferred host plants, thereby investigation on functional co-evolution and divergence of olfactory genes seems to be necessary and is of great interest. In the odorant detection pathway, olfactory receptor co-receptor (Orco) plays critical role in the perception of odors. In this study, we identified the full-length cDNA sequences encoding three putative Orcos (AsutOrco, AfasOrco, and LpraOrco) in bug species of A. suturalis, A. fasciaticollis, and L. pratensis based on homology cloning method. Next, sequence alignment, membrane topology and gene structure analysis showed that these three Orco orthologs together with previously reported AlinOrco and AlucOrco shared high amino acid identities and similar topology structure, but had different gene structure especially at the length and insertion sites of introns. Furthermore, the evolutional estimation on the ratios of non-synonymous to synonymous (Ka/Ks) revealed that Orco genes were under strong purifying selection, but the degrees of variation were significant different between genera. The results of quantitative real-time PCR experiments showed that these five Orco genes had a similar antennae-biased tissue expression pattern. Taking these data together, it is thought that Orco genes in the mirid species could share conserved olfaction roles but had different evolution rates. These findings would lay a foundation to further investigate the molecular mechanisms of evolutionary interactions between mirid bugs and their host plants, which might in turn contribute to the development of pest management strategy for mirid bugs.
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Affiliation(s)
- Qi Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Qian Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,Department of Plant Protection, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
| | - Yan-Le Zhou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,DanDong Entry-Exit Inspection and Quarantine Bureau, Dandong, China
| | - Shuang Shan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Huan-Huan Cui
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yong Xiao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Kun Dong
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Adel Khashaveh
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Liang Sun
- Key Laboratory of Tea Quality and Safety Control, Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China
| | - Yong-Jun Zhang
- 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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Corcoran JA, Sonntag Y, Andersson MN, Johanson U, Löfstedt C. Endogenous insensitivity to the Orco agonist VUAA1 reveals novel olfactory receptor complex properties in the specialist fly Mayetiola destructor. Sci Rep 2018; 8:3489. [PMID: 29472565 PMCID: PMC5823858 DOI: 10.1038/s41598-018-21631-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/06/2018] [Indexed: 11/12/2022] Open
Abstract
Insect olfactory receptors are routinely expressed in heterologous systems for functional characterisation. It was recently discovered that the essential olfactory receptor co-receptor (Orco) of the Hessian fly, Mayetiola destructor (Mdes), does not respond to the agonist VUAA1, which activates Orco in all other insects analysed to date. Here, using a mutagenesis-based approach we identified three residues in MdesOrco, located in different transmembrane helices as supported by 3D modelling, that confer sensitivity to VUAA1. Reciprocal mutations in Drosophila melanogaster (Dmel) and the noctuid moth Agrotis segetum (Aseg) Orcos diminish sensitivity of these proteins to VUAA1. Additionally, mutating these residues in DmelOrco and AsegOrco compromised odourant receptor (OR) dependent ligand-induced Orco activation. In contrast, both wild-type and VUAA1-sensitive MdesOrco were capable of forming functional receptor complexes when coupled to ORs from all three species, suggesting unique complex properties in M. destructor, and that not all olfactory receptor complexes are “created” equal.
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Affiliation(s)
| | - Yonathan Sonntag
- Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, Lund, Sweden
| | | | - Urban Johanson
- Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, Lund, Sweden
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17
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Yang K, Huang LQ, Ning C, Wang CZ. Two single-point mutations shift the ligand selectivity of a pheromone receptor between two closely related moth species. eLife 2017; 6:29100. [PMID: 29063835 PMCID: PMC5673308 DOI: 10.7554/elife.29100] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/22/2017] [Indexed: 11/13/2022] Open
Abstract
Male moths possess highly sensitive and selective olfactory systems that detect sex pheromones produced by their females. Pheromone receptors (PRs) play a key role in this process. The PR HassOr14b is found to be tuned to (Z)-9-hexadecenal, the major sex-pheromone component, in Helicoverpa assulta. HassOr14b is co-localized with HassOr6 or HassOr16 in two olfactory sensory neurons within the same sensilla. As HarmOr14b, the ortholog of HassOr14b in the closely related species Helicoverpa armigera, is tuned to another chemical (Z)-9-tetradecenal, we study the amino acid residues that determine their ligand selectivity. Two amino acids located in the transmembrane domains F232I and T355I together determine the functional difference between the two orthologs. We conclude that species-specific changes in the tuning specificity of the PRs in the two Helicoverpa moth species could be achieved with just a few amino acid substitutions, which provides new insights into the evolution of closely related moth species.
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Affiliation(s)
- Ke Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ling-Qiao Huang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Chao Ning
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chen-Zhu Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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Candidate pheromone receptors of codling moth Cydia pomonella respond to pheromones and kairomones. Sci Rep 2017; 7:41105. [PMID: 28117454 PMCID: PMC5259778 DOI: 10.1038/srep41105] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 12/15/2016] [Indexed: 11/09/2022] Open
Abstract
Olfaction plays a dominant role in the mate-finding and host selection behaviours of the codling moth (Cydia pomonella), an important pest of apple, pear and walnut orchards worldwide. Antennal transcriptome analysis revealed a number of abundantly expressed genes related to the moth olfactory system, including those encoding the olfactory receptors (ORs) CpomOR1, CpomOR3 and CpomOR6a, which belong to the pheromone receptor (PR) lineage, and the co-receptor (CpomOrco). Using heterologous expression, in both Drosophila olfactory sensory neurones and in human embryonic kidney cells, together with electrophysiological recordings and calcium imaging, we characterize the basic physiological and pharmacological properties of these receptors and demonstrate that they form functional ionotropic receptor channels. Both the homomeric CpomOrco and heteromeric CpomOrco + OR complexes can be activated by the common Orco agonists VUAA1 and VUAA3, as well as inhibited by the common Orco antagonists amiloride derivatives. CpomOR3 responds to the plant volatile compound pear ester ethyl-(E,Z)-2,4-decadienoate, while CpomOR6a responds to the strong pheromone antagonist codlemone acetate (E,E)-8,10-dodecadien-1-yl acetate. These findings represent important breakthroughs in the deorphanization of codling moth pheromone receptors, as well as more broadly into insect ecology and evolution and, consequently, for the development of sustainable pest control strategies based on manipulating chemosensory communication.
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19
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Wang B, Liu Y, He K, Wang G. Comparison of research methods for functional characterization of insect olfactory receptors. Sci Rep 2016; 6:32806. [PMID: 27633402 PMCID: PMC5025650 DOI: 10.1038/srep32806] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 08/10/2016] [Indexed: 12/11/2022] Open
Abstract
Insect olfactory receptors (ORs) in the peripheral olfactory system play an important role detecting elements of information from the environment. At present, various approaches are used for deorphanizing of ORs in insect. In this study, we compared methods for functional analysis of ORs in vitro and in vivo taking the candidate pheromone receptor OR13 of Helicoverpa assulta (HassOR13) as the object of our experiments. We found that the natural system was more sensitive than those utilizing transgenic Drosophila. The two-electrode voltage-clamp recording is more suitable for functional screening of large numbers of ORs, while the in vivo transgenic Drosophila system could prove more accurate to further validate the function of a specific OR. We also found that, among the different solvents used to dissolve pheromones and odorants, hexane offered good reproducibility and high sensitivity. Finally, the function of ORs was indirectly confirmed in transgenic Drosophila, showing that odor-activation of ORs-expressing olfactory receptor neurons (ORNs) can mediate behavioral choices. In summary, our results compare advantages and drawbacks of different approaches, thus helping in the choice of the method most suitable, in each specific situation, for deorphanizing insect ORs.
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Affiliation(s)
- Bing Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yang Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Kang He
- 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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20
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Liu H, Liu T, Xie L, Wang X, Deng Y, Chen CH, James AA, Chen XG. Functional analysis of Orco and odorant receptors in odor recognition in Aedes albopictus. Parasit Vectors 2016; 9:363. [PMID: 27350348 PMCID: PMC4924234 DOI: 10.1186/s13071-016-1644-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 06/13/2016] [Indexed: 11/10/2022] Open
Abstract
Background Aedes albopictus is a globally invasive mosquito and a major vector of arboviruses, including dengue, Zika and Chikungunya. Olfactory-related behaviors, particularly host-seeking, offer opportunities to disrupt the disease-transmission process. A better understanding of odorant receptors (ORs) may assist in explaining host selection and location, and contribute to novel strategy of vector control. Methods Based on previous prediction of 158 putative odorant receptors by Ae. albopictus genome analysis, 29 AalORs were selected for tissue-specific expression profiles in the present study. AalOrco (AalOR7), AalOR10 and AalOR88, highly expressed in female olfactory tissues, were chosen for further structure predictions as well as functional validation including calcium imaging assay in human embryonic kidney (HEK293) cells and RNA interference assay in Ae. albopictus. We also conducted electrophysiological and behavioral assays in mosquitoes after RNA interference of the three genes to determine their roles in host-seeking. Results The results support previous conclusions that individual conventional (ORXs) and Orco can form heteromeric complexes to recognize odorants and respond to components of human volatiles in HEK293 cells. The reduction of AalOrco transcript levels led to a significant decrease in host-seeking and confusion in host preference. In contrast, AalOR10 and AalOR88 knockdown mosquitoes showed no significant behavioral differences compared with controls. The functions of conventional ORs at least AalOR10 and AalOR88 are abolished with inhibited expression of the Orco gene orthologs, along with the concomitant relevant olfactory behavior. Conclusions Combining structural and functional data, we conclude that the product of the Orco gene in this mosquito is crucial for transmitting olfactory signaling and conventional ORs contribute directly to odorant recognition. Our results provide insight into the linkage between odorant receptors and host-seeking in this important vector species. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1644-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hongmei Liu
- Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Tong Liu
- Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Lihua Xie
- Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Xiaoming Wang
- Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Yuhua Deng
- Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Chun-Hong Chen
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli, Taiwan
| | - Anthony A James
- Departments of Microbiology and Molecular Genetics, and Molecular Biology and Biochemistry, 3205 McGaugh Hall, University of California, Irvine, CA, 92697-3900, USA
| | - Xiao-Guang Chen
- Department of Pathogen Biology, Key Laboratory of Prevention and Control of Emerging Infectious Diseases of Guangdong Higher Education Institutes, School of Public Health, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
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21
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Zhang R, Gao G, Chen H. Silencing of the olfactory co-receptor gene in Dendroctonus armandi leads to EAG response declining to major host volatiles. Sci Rep 2016; 6:23136. [PMID: 26979566 PMCID: PMC4793246 DOI: 10.1038/srep23136] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 02/29/2016] [Indexed: 11/09/2022] Open
Abstract
In this study, a polymerase chain reaction (PCR) based on homology genes of Orco was utilized to identify DarmOrco, which is essential for olfaction in D. armandi. The results showed that DarmOrco shares significant sequence homology with Orco proteins had known in other insects. Quantitative real-time PCR (qRT-PCR) analysis suggested that DarmOrco was abundantly expressed in adult D. armandi; by contrast, DarmOrco showed trace amounts of expression level in other stages. Of different tissues, DarmOrco expression level was the highest in the antennae. In order to understand the functional significance of Orco, we injected siRNA of DarmOrco into the conjunctivum between the second and third abdominal segments, and evaluated its expression after siRNA injected for 24 h, 48 h and 72 h. The results of qRT-PCR demonstrated that the reduction of mRNA expression level was significant (~80%) in DarmOrco siRNA-treated D. armandi than in water-injected and non-injected controls. The electroantennogram responses of females and males to 11 major volatiles of its host, were also reduced (30~68% for females; 16~70% for males) in siRNA-treated D. armandi compared with the controls. These results suggest that DarmOrco is crucial in mediating odorant perception.
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Affiliation(s)
- Ranran Zhang
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Guanqun Gao
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Hui Chen
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
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22
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Latorre-Estivalis JM, de Oliveira ES, Beiral Esteves B, Santos Guimarães L, Neves Ramos M, Lorenzo MG. Patterns of expression of odorant receptor genes in a Chagas disease vector. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 69:71-81. [PMID: 26003917 DOI: 10.1016/j.ibmb.2015.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 04/29/2015] [Accepted: 05/01/2015] [Indexed: 06/04/2023]
Abstract
Rhodnius prolixus is a triatomine bug acting as a relevant vector of Chagas disease for which the genome sequence has been recently made available. Based on this information, a set of olfactory (ORs) and ionotropic receptor (IRs) genes potentially related to olfactory processes was characterized, and the expression patterns along bug development and in different structures potentially involved in promoting chemosensory-mediated behaviors were studied. For this, diverse bioinformatic procedures were used to validate gene models analyzing their structural and functional features and designing specific primers. Evolutionary relationships among R. prolixus olfactory coreceptors (RproOrco, RproIR25a, RproIR8a and RproIR76b) and their orthologues from other insects were shown to have mostly good bootstrap support values in phylogenetic trees. Moreover, antennal expression was confirmed for most genes included in the study. Both ORs and IRs showed antennal expression along the whole development of bugs of this species, with few exceptional receptors showing gradually increasing expression or expression restricted to the antennae of adult bugs. Finally, the expression of most of the selected genes was confirmed in other structures, such as rostri, tarsi, tibial pads and genitalia, which are potentially involved in promoting chemosensory-mediated behaviors. These results are discussed in terms of their relevance to advance in the understanding of the molecular bases of triatomine behavior.
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Affiliation(s)
- Jose Manuel Latorre-Estivalis
- Vector Behavior and Pathogen Interaction Group, Centro de Pesquisas René Rachou (CPqRR) - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil.
| | - Emerson Soares de Oliveira
- Vector Behavior and Pathogen Interaction Group, Centro de Pesquisas René Rachou (CPqRR) - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | - Barbara Beiral Esteves
- Vector Behavior and Pathogen Interaction Group, Centro de Pesquisas René Rachou (CPqRR) - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | - Letícia Santos Guimarães
- Vector Behavior and Pathogen Interaction Group, Centro de Pesquisas René Rachou (CPqRR) - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | - Marina Neves Ramos
- Vector Behavior and Pathogen Interaction Group, Centro de Pesquisas René Rachou (CPqRR) - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | - Marcelo Gustavo Lorenzo
- Vector Behavior and Pathogen Interaction Group, Centro de Pesquisas René Rachou (CPqRR) - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
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23
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Carraher C, Dalziel J, Jordan MD, Christie DL, Newcomb RD, Kralicek AV. Towards an understanding of the structural basis for insect olfaction by odorant receptors. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 66:31-41. [PMID: 26416146 DOI: 10.1016/j.ibmb.2015.09.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 09/16/2015] [Accepted: 09/16/2015] [Indexed: 06/05/2023]
Abstract
Insects have co-opted a unique family of seven transmembrane proteins for odour sensing. Odorant receptors are believed to have evolved from gustatory receptors somewhere at the base of the Hexapoda and have expanded substantially to become the dominant class of odour recognition elements within the Insecta. These odorant receptors comprise an obligate co-receptor, Orco, and one of a family of highly divergent odorant "tuning" receptors. The two subunits are thought to come together at some as-yet unknown stoichiometry to form a functional complex that is capable of both ionotropic and metabotropic signalling. While there are still no 3D structures for these proteins, site-directed mutagenesis, resonance energy transfer, and structural modelling efforts, all mainly on Drosophila odorant receptors, are beginning to inform hypotheses of their structures and how such complexes function in odour detection. Some of the loops, especially the second extracellular loop that has been suggested to form a lid over the binding pocket, and the extracellular regions of some transmembrane helices, especially the third and to a less extent the sixth and seventh, have been implicated in ligand recognition in tuning receptors. The possible interaction between Orco and tuning receptor subunits through the final intracellular loop and the adjacent transmembrane helices is thought to be important for transducing ligand binding into receptor activation. Potential phosphorylation sites and a calmodulin binding site in the second intracellular loop of Orco are also thought to be involved in regulating channel gating. A number of new methods have recently been developed to express and purify insect odorant receptor subunits in recombinant expression systems. These approaches are enabling high throughput screening of receptors for agonists and antagonists in cell-based formats, as well as producing protein for the application of biophysical methods to resolve the 3D structure of the subunits and their complexes.
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Affiliation(s)
- Colm Carraher
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand
| | - Julie Dalziel
- Food Nutrition & Health Team, Food & Bio-based Products Group, AgResearch Private Bag 11008, Palmerston North 4442, New Zealand
| | - Melissa D Jordan
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand
| | - David L Christie
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Richard D Newcomb
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Andrew V Kralicek
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand.
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Benton R. Multigene Family Evolution: Perspectives from Insect Chemoreceptors. Trends Ecol Evol 2015; 30:590-600. [DOI: 10.1016/j.tree.2015.07.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/17/2015] [Accepted: 07/21/2015] [Indexed: 10/23/2022]
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Montagné N, de Fouchier A, Newcomb RD, Jacquin-Joly E. Advances in the identification and characterization of olfactory receptors in insects. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 130:55-80. [PMID: 25623337 DOI: 10.1016/bs.pmbts.2014.11.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Olfactory receptors (ORs) are the key elements of the molecular machinery responsible for the detection of odors in insects. Since their initial discovery in Drosophila melanogaster at the beginning of the twenty-first century, insect ORs have been the focus of intense research, both for fundamental knowledge of sensory systems and for their potential as novel targets for the development of products that could impact harmful behaviors of crop pests and disease vectors. In recent years, studies on insect ORs have entered the genomic era, with an ever-increasing number of OR genes being characterized every year through the sequencing of genomes and transcriptomes. With the upcoming release of genomic sequences from hundreds of insect species, the insect OR family could very well become the largest multigene family known. This extremely rapid identification of ORs in many insects is driving the necessity for the development of high-throughput technologies that will allow the identification of ligands for this unprecedented number of receptors. Moreover, such technologies will also be important for the development of agonists or antagonists that could be used in the fight against pest insects.
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Affiliation(s)
- Nicolas Montagné
- Institute of Ecology & Environmental Sciences of Paris, UPMC-Sorbonne Universités, Paris, France
| | - Arthur de Fouchier
- Institute of Ecology & Environmental Sciences of Paris, INRA, Versailles, France
| | - Richard D Newcomb
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
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Suh E, Bohbot J, Zwiebel LJ. Peripheral olfactory signaling in insects. CURRENT OPINION IN INSECT SCIENCE 2014; 6:86-92. [PMID: 25584200 PMCID: PMC4288021 DOI: 10.1016/j.cois.2014.10.006] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Olfactory signaling is a crucial component in the life history of insects. The development of precise and parallel mechanisms to analyze the tremendous amount of chemical information from the environment and other sources has been essential to their evolutionary success. Considerable progress has been made in the study of insect olfaction fueled by bioinformatics- based utilization of genomics along with rapid advances in functional analyses. Here we review recent progress in our rapidly emerging understanding of insect peripheral sensory reception and signal transduction. These studies reveal that the nearly unlimited chemical space insects encounter is covered by distinct chemosensory receptor repertoires that are generally derived by species-specific, rapid gene gain and loss, reflecting the evolutionary consequences of adaptation to meet their specific biological needs. While diverse molecular mechanisms have been put forth, often in the context of controversial models, the characterization of the ubiquitous, highly conserved and insect-specific Orco odorant receptor co-receptor has opened the door to the design and development of novel insect control methods to target agricultural pests, disease vectors and even nuisance insects.
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Affiliation(s)
- Eunho Suh
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37205
| | - Jonathan Bohbot
- Department of Entomology, The Hebrew University, Rehovot 76100, Israel
| | - Laurence J. Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37205
- Correspondence to be sent to: Laurence J. Zwiebel, Department of Biological Sciences, Vanderbilt University, Nashville, USA.
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Corcoran JA, Jordan MD, Carraher C, Newcomb RD. A novel method to study insect olfactory receptor function using HEK293 cells. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 54:22-32. [PMID: 25174788 DOI: 10.1016/j.ibmb.2014.08.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/05/2014] [Accepted: 08/19/2014] [Indexed: 05/27/2023]
Abstract
The development of rapid and reliable assays to characterize insect odorant receptors (ORs) and pheromone receptors (PRs) remains a challenge for the field. Typically ORs and PRs are functionally characterized either in vivo in transgenic Drosophila or in vitro through expression in Xenopus oocytes. While these approaches have succeeded, they are not well suited for high-throughput screening campaigns, primarily due to inherent characteristics that limit their ability to screen large quantities of compounds in a short period of time. The development of a practical, robust and consistent in vitro assay for functional studies on ORs and PRs would allow for high-throughput screening for ligands, as well as for compounds that could be used as novel olfactory-based pest management tools. Here we describe a novel method of utilizing human embryonic kidney cells (HEK293) transfected with inducible receptor constructs for the functional characterization of ORs in 96-well plates using a fluorescent spectrophotometer. Using EposOrco and EposOR3 from the pest moth, Epiphyas postvittana as an example, we generated HEK293 cell lines with robust and consistent responses to ligands in functional assays. Single-cell sorting of cell lines by FACS facilitated the selection of isogenic cell lines with maximal responses, and the addition of epitope tags on the N-termini allowed the detection of recombinant proteins in homogenates by western blot and in cells by immunocytochemistry. We thoroughly describe the methods used to generate these OR-expressing cell lines, demonstrating that they have all the necessary features required for use in high-throughput screening platforms.
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Affiliation(s)
- Jacob A Corcoran
- School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand
| | - Melissa D Jordan
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand
| | - Colm Carraher
- The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand
| | - Richard D Newcomb
- School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand.
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Hughes DT, Wang G, Zwiebel LJ, Luetje CW. A determinant of odorant specificity is located at the extracellular loop 2-transmembrane domain 4 interface of an Anopheles gambiae odorant receptor subunit. Chem Senses 2014; 39:761-9. [PMID: 25270378 DOI: 10.1093/chemse/bju048] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To explore the structural basis for odorant specificity in odorant receptors of the human malaria vector mosquito, Anopheles gambiae, odorant-binding subunits (Agam\Ors) expressed in Xenopus oocytes in combination with Agam\Orco (coreceptor subunit) were assayed by 2-electrode voltage clamp against 25 structurally related odorants. Agam\Or13 and Agam\Or15 display 82% amino acid identity and had similar, but somewhat distinct odorant response profiles. The ratio of acetophenone to 4-methylphenol responses was used in a mutation-based analysis of Agam\Or15, interchanging 37 disparate residues between Agam\Or15 and Agam\Or13. Eleven mutations caused significant changes in odorant responsiveness. Mutation of alanine 195 resulted in the largest shift in response ratio from Agam\Or15 toward Agam\Or13. Concentration-response analysis for a series of mutations of residue 195 revealed a large effect on acetophenone sensitivity, with EC50 values varying by >1800-fold and correlating with residue side chain length. Similar results were obtained for propiophenone and benzaldehyde. But, for other odorants, such as 4-methylphenol, 4-methylbenzaldehyde, and 4-methylpropiophenone, the effect of mutation was much smaller (EC50 values varied by ≤16-fold). These results show that alanine 195, putatively located at the second extracellular loop/fourth transmembrane domain interface, plays a critical role in determining the odorant response specificity of Agam\Or15.
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Affiliation(s)
- David T Hughes
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33101, USA and Present address: University of Colorado School of Medicine, 13001 E. 17th Place, Aurora, CO 80045, USA
| | - Guirong Wang
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA Present address: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100101, China
| | - Laurence J Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Charles W Luetje
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33101, USA and
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Turner RM, Derryberry SL, Kumar BN, Brittain T, Zwiebel LJ, Newcomb RD, Christie DL. Mutational analysis of cysteine residues of the insect odorant co-receptor (Orco) from Drosophila melanogaster reveals differential effects on agonist- and odorant-tuning receptor-dependent activation. J Biol Chem 2014; 289:31837-31845. [PMID: 25271160 DOI: 10.1074/jbc.m114.603993] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insect odorant receptors are heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor (ORx) and a highly conserved co-receptor known as Orco. Orco is found only in insects, and very little is known about its structure and the mechanism leading to channel activation. In the absence of an ORx, Orco forms homomeric channels that can be activated by a synthetic agonist, VUAA1. Drosophila melanogaster Orco (DmelOrco) contains eight cysteine amino acid residues, six of which are highly conserved. In this study, we replaced individual cysteine residues with serine or alanine and expressed Orco mutants in Flp-In 293 T-Rex cells. Changes in intracellular Ca(2+) levels were used to determine responses to VUAA1. Replacement of two cysteines (Cys-429 and Cys-449) in a predicted intracellular loop (ICL3), individually or together, gave variants that all showed similar increases in the rate of response and sensitivity to VUAA1 compared with wild-type DmelOrco. Kinetic modeling indicated that the response of the Orco mutants to VUAA1 was faster than wild-type Orco. The enhanced sensitivity and faster response of the Cys mutants was confirmed by whole-cell voltage clamp electrophysiology. In contrast to the results from direct agonist activation of Orco, the two cysteine replacement mutants when co-expressed with a tuning receptor (DmelOR22a) showed an ∼10-fold decrease in potency for activation by 2-methyl hexanoate. Our work has shown that intracellular loop 3 is important for Orco channel activation. Importantly, this study also suggests differences in the structural requirements for the activation of homomeric and heteromeric Orco channel complexes.
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Affiliation(s)
- Rebecca M Turner
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Stephen L Derryberry
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37232, and
| | - Brijesh N Kumar
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Thomas Brittain
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Laurence J Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37232, and
| | - Richard D Newcomb
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand,; Plant & Food Research, Private Bag 92169, Auckland 1142, New Zealand
| | - David L Christie
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand,.
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Missbach C, Dweck HK, Vogel H, Vilcinskas A, Stensmyr MC, Hansson BS, Grosse-Wilde E. Evolution of insect olfactory receptors. eLife 2014; 3:e02115. [PMID: 24670956 PMCID: PMC3966513 DOI: 10.7554/elife.02115] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The olfactory sense detects a plethora of behaviorally relevant odor molecules; gene families involved in olfaction exhibit high diversity in different animal phyla. Insects detect volatile molecules using olfactory (OR) or ionotropic receptors (IR) and in some cases gustatory receptors (GRs). While IRs are expressed in olfactory organs across Protostomia, ORs have been hypothesized to be an adaptation to a terrestrial insect lifestyle. We investigated the olfactory system of the primary wingless bristletail Lepismachilis y-signata (Archaeognatha), the firebrat Thermobia domestica (Zygentoma) and the neopteran leaf insect Phyllium siccifolium (Phasmatodea). ORs and the olfactory coreceptor (Orco) are with very high probability lacking in Lepismachilis; in Thermobia we have identified three Orco candidates, and in Phyllium a fully developed OR/Orco-based system. We suggest that ORs did not arise as an adaptation to a terrestrial lifestyle, but evolved later in insect evolution, with Orco being present before the appearance of ORs. DOI:http://dx.doi.org/10.7554/eLife.02115.001 Detecting chemical cues can be a matter of life or death for insects, and many employ three families of receptor proteins to detect a broad range of odors. Members of one of these receptor families, the olfactory receptors, form a complex with another protein, the olfactory coreceptor that is essential for both positioning and stabilizing the receptor, as well as the actual function. Crustaceans share a common ancestor with insects, and since they do not have olfactory receptors it has been proposed that these receptors evolved when prehistoric insects moved from the sea to live on land. According to this idea, olfactory receptors evolved because these ancestors needed to be able to detect odor molecules floating in the air rather than dissolved in water. Previous research on insect olfactory receptors has focused on insects with wings. Missbach et al. have now used a wide range of techniques to investigate how evolutionarily older wingless insect groups detect scents. As all investigated groups evolved from a common ancestor at different times these experiments allow tracking of the historical development of olfactory receptors. In the wingless species that is more closely related to the flying insects there was evidence of the presence of multiple coreceptors but not the olfactory receptors themselves. In the most basal insects no evidence for any part of the olfactory receptor-based system was found. This indicates that the main olfactory receptors evolved independently of the coreceptor long after the migration of insects from water to land. Missbach et al. suggest that olfactory receptors instead developed far later, around the time when vascular plants spread and insects developed the ability to fly. DOI:http://dx.doi.org/10.7554/eLife.02115.002
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Affiliation(s)
- Christine Missbach
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
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