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Riabinina O, Task D, Marr E, Lin CC, Alford R, O'Brochta DA, Potter CJ. Organization of olfactory centres in the malaria mosquito Anopheles gambiae. Nat Commun 2016; 7:13010. [PMID: 27694947 PMCID: PMC5063964 DOI: 10.1038/ncomms13010] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/25/2016] [Indexed: 02/01/2023] Open
Abstract
Mosquitoes are vectors for multiple infectious human diseases and use a variety of sensory cues (olfactory, temperature, humidity and visual) to locate a human host. A comprehensive understanding of the circuitry underlying sensory signalling in the mosquito brain is lacking. Here we used the Q-system of binary gene expression to develop transgenic lines of Anopheles gambiae in which olfactory receptor neurons expressing the odorant receptor co-receptor (Orco) gene are labelled with GFP. These neurons project from the antennae and maxillary palps to the antennal lobe (AL) and from the labella on the proboscis to the suboesophageal zone (SEZ), suggesting integration of olfactory and gustatory signals occurs in this brain region. We present detailed anatomical maps of olfactory innervations in the AL and the SEZ, identifying glomeruli that may respond to human body odours or carbon dioxide. Our results pave the way for anatomical and functional neurogenetic studies of sensory processing in mosquitoes.
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Affiliation(s)
- Olena Riabinina
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Darya Task
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Elizabeth Marr
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Chun-Chieh Lin
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Robert Alford
- University of Maryland College Park, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
| | - David A O'Brochta
- University of Maryland College Park, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
| | - Christopher J Potter
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
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Clark JT, Ray A. Olfactory Mechanisms for Discovery of Odorants to Reduce Insect-Host Contact. J Chem Ecol 2016; 42:919-930. [PMID: 27628342 DOI: 10.1007/s10886-016-0770-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 08/25/2016] [Accepted: 09/08/2016] [Indexed: 11/29/2022]
Abstract
Insects have developed highly sophisticated and sensitive olfactory systems to find animal or plant hosts for feeding. Some insects vector pathogens that cause diseases in hundreds of millions of people and destroy billions of dollars of food products every year. There is great interest, therefore, in understanding how the insect olfactory system can be manipulated to reduce their contact with hosts. Here, we review recent advances in our understanding of insect olfactory detection mechanisms, which may serve as a foundation for designing insect control programs based on manipulation of their behaviors by using odorants. Because every insect species has a unique set of olfactory receptors and olfactory-mediated behaviors, we focus primarily on general principles of odor detection that potentially apply to most insects. While these mechanisms have emerged from studies on model systems for study of insect olfaction, such as Drosophila melanogaster, they provide a foundation for discovery of odorants to repel vector insects or reduce their host-seeking behavior.
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Affiliation(s)
- Jonathan T Clark
- Interdepartmental Neuroscience Program, University of California, Riverside, CA, 92521, USA
| | - Anandasankar Ray
- Interdepartmental Neuroscience Program, University of California, Riverside, CA, 92521, USA. .,Entomology Department, University of California, Riverside, CA, 92521, USA. .,Center for Disease Vector Research, University of California, Riverside, CA, 92521, USA.
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53
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Antennal transcriptome and differential expression of olfactory genes in the yellow peach moth, Conogethes punctiferalis (Lepidoptera: Crambidae). Sci Rep 2016; 6:29067. [PMID: 27364081 PMCID: PMC4929561 DOI: 10.1038/srep29067] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/14/2016] [Indexed: 11/09/2022] Open
Abstract
The yellow peach moth (YPM), Conogethes punctiferalis (Guenée), is a multivoltine insect pest of crops and fruits. Antennal-expressed receptors are important for insects to detect olfactory cues for host finding, mate attraction and oviposition site selection. However, few olfactory related genes were reported in YPM until now. In the present study, we sequenced and characterized the antennal transcriptomes of male and female YPM. In total, 15 putative odorant binding proteins (OBPs), 46 putative odorant receptors (ORs) and 7 putative ionotropic receptors (IRs) were annotated and identified as olfactory-related genes of C. punctiferalis. Further analysis of RT-qPCR revealed that all these olfactory genes are primarily or uniquely expressed in male and female antennae. Among which, 3 OBPs (OBP4, OBP8 and PBP2) and 4 ORs (OR22, OR26, OR44 and OR46) were specially expressed in male antennae, whereas 4 ORs (OR5, OR16, OR25 and OR42) were primarily expressed in female antennae. The predicted protein sequences were compared with homologs in other lepidopteran species and model insects, which showed high sequence homologies between C. punctiferalis and O. furnacalis. Our work allows for further functional studies of pheromone and general odorant detection genes, which might be meaningful targets for pest management.
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54
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Sparks JT, Dickens JC. Bitter-sensitive gustatory receptor neuron responds to chemically diverse insect repellents in the common malaria mosquito Anopheles quadrimaculatus. Naturwissenschaften 2016; 103:39. [PMID: 27108454 DOI: 10.1007/s00114-016-1367-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 01/20/2016] [Accepted: 04/15/2016] [Indexed: 11/25/2022]
Abstract
Female mosquitoes feed on blood from animal hosts to obtain nutritional resources used for egg production. These contacts facilitate the spread of harmful human diseases. Chemical repellents are used to disrupt mosquito host-seeking and blood-feeding behaviors; however, little is known about the gustatory sensitivity of mosquitoes to known repellents. Here, we recorded electrical responses from gustatory receptor neurons (GRNs) housed within the labellar sensilla of female Anopheles quadrimaculatus to N,N-diethyl-3-methylbenzamide (DEET), picaridin, IR3535, 2-undecanone, p-menthane-3,8-diol, geraniol, trans-2-hexen-1-ol, quinine, and quinidine. A bitter-sensitive GRN responded to all tested repellents and quinine, a known feeding deterrent. Responses of the bitter-sensitive neuron to quinine and an isomer, quinidine, did not differ. Delayed bursts of electrical activity were observed in response to continuous stimulation with synthetic repellents at high concentrations. Electrophysiological recordings from bitter-sensitive GRNs associated with mosquito gustatory sensilla represent a convenient model to evaluate candidate repellents.
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Affiliation(s)
- Jackson T Sparks
- United States Department of Agriculture, Agricultural Research Service, Henry A. Wallace Beltsville Agricultural Research Center, Invasive Insect Biocontrol and Behavior Laboratory, Bldg. 007, Rm. 030, 10300 Baltimore Avenue, Beltsville, MD, 20705, USA
| | - Joseph C Dickens
- United States Department of Agriculture, Agricultural Research Service, Henry A. Wallace Beltsville Agricultural Research Center, Invasive Insect Biocontrol and Behavior Laboratory, Bldg. 007, Rm. 030, 10300 Baltimore Avenue, Beltsville, MD, 20705, USA.
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55
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Campos D, Gravato C, Quintaneiro C, Soares AMVM, Pestana JLT. Responses of the aquatic midge Chironomus riparius to DEET exposure. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 172:80-85. [PMID: 26773354 DOI: 10.1016/j.aquatox.2015.12.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/18/2015] [Accepted: 12/29/2015] [Indexed: 06/05/2023]
Abstract
N,N-diethyl-3-methylbenzamide (DEET) is the active ingredient of many commercial insect repellents. Despite being detected worldwide in effluents, surface water and groundwater, there is still limited information on DEET's toxicity toward non-target aquatic invertebrates. Thus, our main objective was to assess the effects of DEET in the life cycle of Chironomus riparius and assess its biochemical effects. Laboratory assays showed that DEET reduced developmental rates (reduced larval growth, delayed emergence) of C. riparius larvae and also caused a decrease in the size of adult midges. Concerning the biochemical responses, a short exposure to DEET caused no effects in lipid peroxidation, despite the significant inhibition of catalase and glutathione-S-transferase activities and of total glutathione contents. Moreover, inhibition of acetylcholinesterase activity was also observed showing neurotoxic effects. Environmental risk assessment of insect repellents is needed. Our results showed moderate toxicity of DEET toward C. riparius, however, due to their mode of action, indirect ecological effects of DEET and of other insect repellents cannot be excluded and should be evaluated.
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Affiliation(s)
- Diana Campos
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Carlos Gravato
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Carla Quintaneiro
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Amadeu M V M Soares
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - João L T Pestana
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
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Gonzalez PV, González Audino PA, Masuh HM. Behavioral Response of Aedes aegypti (Diptera: Culicidae) Larvae to Synthetic and Natural Attractants and Repellents. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:1315-1321. [PMID: 26352935 DOI: 10.1093/jme/tjv136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/23/2015] [Indexed: 06/05/2023]
Abstract
Aedes aegypti (L.) (Diptera: Culicidae) is the key vector of three important arboviral diseases: dengue, yellow fever, and chikungunya. Immature stages of this species inhabit human-made containers placed in residential landscapes. In this study, we evaluated a few compounds in a sensitive behavioral assay with Ae. aegypti larvae. The orientation of larvae to different compounds was surveyed using a performance index (PI). The PI represents the response to each odorant, where a value of +1 is indicative of full attraction and -1 represents complete repulsion. The widely used insect repellent N, N-diethyl-m-toluamide elicited a significantly negative PI, as did acetophenone and indole. A yeast extract, a known food source, elicited a significantly positive PI, as did 2-methylphenol, 1-octen-3-ol, 3-methylphenol, and fish food. On the other hand, no response was observed for the essential oil of Eucalyptus grandis x Eucalyptus camaldulensis at the concentration evaluated. Pretreatment of larvae with N-ethylmaleimide and ablation of the antennae resulted in a suppression of behavioral responses. The overall mobility of ablated larvae was indistinguishable from unablated controls, and absence of any visible locomotor dysfunction was observed. This work is a contribution to the study of the chemical ecology of disease vectors with the aim of developing more efficient tools for surveillance and control.Natural and synthetic compounds attractive to Ae. aegypti larvae should be incorporated into integrated pest management programs through the use of baited traps or by improving the efficacy of larvicides commonly used in control campaigns.
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Affiliation(s)
- Paula V Gonzalez
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires, Argentina
| | - Paola A González Audino
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires, Argentina
| | - Héctor M Masuh
- Centro de Investigaciones de Plagas e Insecticidas (CONICET- CITEDEF), Juan Bautista de La Salle 4397, B1603ALO, Villa Martelli, Buenos Aires, Argentina.
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57
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Wang Z, Yang P, Chen D, Jiang F, Li Y, Wang X, Kang L. Identification and functional analysis of olfactory receptor family reveal unusual characteristics of the olfactory system in the migratory locust. Cell Mol Life Sci 2015; 72:4429-43. [PMID: 26265180 PMCID: PMC4611004 DOI: 10.1007/s00018-015-2009-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/20/2015] [Accepted: 07/30/2015] [Indexed: 01/30/2023]
Abstract
Locusts represent the excellent model of insect olfaction because the animals are equipped with an unusual olfactory system and display remarkable density-dependent olfactory plasticity. However, information regarding receptor molecules involved in the olfactory perception of locusts is very limited. On the basis of genome sequence and antennal transcriptome of the migratory locust, we conduct the identification and functional analysis of two olfactory receptor families: odorant receptors (ORs) and ionotropic receptors (IRs). In the migratory locust, there is an expansion of OR family (142 ORs) while distinctly lower number of IR genes (32 IRs) compared to the repertoires of other insects. The number of the locust OR genes is much less than that of glomeruli in antennal lobe, challenging the general principle of the “one glomerulus-one receptor” observed in other insects. Most OR genes are found in tandem arrays, forming two large lineage-specific subfamilies in the phylogenetic tree. The “divergent IR” subfamily displays a significant contraction, and most of the IRs belong to the “antennal IR” subfamily in the locust. Most ORs/IRs have olfactory-specific expression while some broadly- or internal-expressed members are also found. Differing from holometabolous insects, the migratory locust contains very similar expression profiles of ORs/IRs between nymph and adult stages. RNA interference and behavioral assays indicate that an OR-based signaling pathway, not IR-based, mediates the attraction of locusts to aggregation pheromones. These discoveries provide insights into the unusual olfactory system of locusts and enhance our understanding of the evolution of insect olfaction.
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Affiliation(s)
- Zhifeng Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Pengcheng Yang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China
| | - Dafeng Chen
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Feng Jiang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yan Li
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, China. .,Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China.
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58
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Omondi BA, Majeed S, Ignell R. Functional development of carbon dioxide detection in the maxillary palp of Anopheles gambiae. ACTA ACUST UNITED AC 2015; 218:2482-8. [PMID: 26056246 PMCID: PMC4528704 DOI: 10.1242/jeb.116798] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 05/25/2015] [Indexed: 12/03/2022]
Abstract
Olfactory information drives several behaviours critical for the survival and persistence of insect pests and vectors. Insect behaviour is variable, linked to their biological needs, and regulated by physiological dynamics. For mosquitoes, CO2 is an important cue that signifies the presence of a host, and which elicits activation and attraction. To investigate the genetic basis of olfactory modulation in mosquitoes, we assayed changes in CO2 detection from receptor gene expression through physiological function to behaviour, associated with the onset of host seeking in the malaria vector, Anopheles gambiae. The gene encoding a subunit of the CO2 receptor, AgGr22, was found to be significantly up-regulated in host-seeking females, consistent with a significant increase in sensitivity of CO2-responsive neurons (cpA) housed in capitate peg sensilla of the maxillary palp. In addition, the odorant receptor AgOr28, which is expressed in cpC neurons, was significantly up-regulated. In contrast, AgOr8, which is expressed in cpB neurons, was not affected by this change in physiological state, in agreement with results for the obligate co-receptor Orco. Moreover, the sensitivity of the cpB neuron to (R)-1-octen-3-ol, a well-known mammalian kairomone, did not change in response to the onset of host seeking. The concentration of CO2 flux influenced both the propensity of A. gambiae to take off into the wind and the speed with which this activation occurred. Female A. gambiae mosquitoes responded to CO2 whether mature for host seeking or not, but onset of host seeking enhanced sensitivity and speed of activation at relevant doses of CO2. Summary: Onset of host-seeking behaviour in malaria mosquitoes is correlated with an increased receptor gene expression, and physiological and behavioural sensitivity to CO2.
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Affiliation(s)
- Bonaventure Aman Omondi
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp 230 53, Sweden Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, Jena 07745, Germany
| | - Shahid Majeed
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp 230 53, Sweden
| | - Rickard Ignell
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp 230 53, Sweden
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59
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Andersson MN, Löfstedt C, Newcomb RD. Insect olfaction and the evolution of receptor tuning. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2015.00053] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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60
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Abd-Ella A, Stankiewicz M, Mikulska K, Nowak W, Pennetier C, Goulu M, Fruchart-Gaillard C, Licznar P, Apaire-Marchais V, List O, Corbel V, Servent D, Lapied B. The Repellent DEET Potentiates Carbamate Effects via Insect Muscarinic Receptor Interactions: An Alternative Strategy to Control Insect Vector-Borne Diseases. PLoS One 2015; 10:e0126406. [PMID: 25961834 PMCID: PMC4427492 DOI: 10.1371/journal.pone.0126406] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/01/2015] [Indexed: 11/25/2022] Open
Abstract
Insect vector-borne diseases remain one of the principal causes of human mortality. In addition to conventional measures of insect control, repellents continue to be the mainstay for personal protection. Because of the increasing pyrethroid-resistant mosquito populations, alternative strategies to reconstitute pyrethroid repellency and knock-down effects have been proposed by mixing the repellent DEET (N,N-Diethyl-3-methylbenzamide) with non-pyrethroid insecticide to better control resistant insect vector-borne diseases. By using electrophysiological, biochemichal, in vivo toxicological techniques together with calcium imaging, binding studies and in silico docking, we have shown that DEET, at low concentrations, interacts with high affinity with insect M1/M3 mAChR allosteric site potentiating agonist effects on mAChRs coupled to phospholipase C second messenger pathway. This increases the anticholinesterase activity of the carbamate propoxur through calcium-dependent regulation of acetylcholinesterase. At high concentrations, DEET interacts with low affinity on distinct M1/M3 mAChR site, counteracting the potentiation. Similar dose-dependent dual effects of DEET have also been observed at synaptic mAChR level. Additionally, binding and in silico docking studies performed on human M1 and M3 mAChR subtypes indicate that DEET only displays a low affinity antagonist profile on these M1/M3 mAChRs. These results reveal a selective high affinity positive allosteric site for DEET in insect mAChRs. Finally, bioassays conducted on Aedes aegypti confirm the synergistic interaction between DEET and propoxur observed in vitro, resulting in a higher mortality of mosquitoes. Our findings reveal an unusual allosterically potentiating action of the repellent DEET, which involves a selective site in insect. These results open exciting research areas in public health particularly in the control of the pyrethroid-resistant insect-vector borne diseases. Mixing low doses of DEET and a non-pyrethroid insecticide will lead to improvement in the efficiency treatments thus reducing both the concentration of active ingredients and side effects for non-target organisms. The discovery of this insect specific site may pave the way for the development of new strategies essential in the management of chemical use against resistant mosquitoes.
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Affiliation(s)
- Aly Abd-Ella
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR 4207 QUASAV, Université d’Angers, UFR SCIENCES, Angers cedex, France
- Plant Protection Department, Faculty of Agriculture, Assiut University, Assiut, Egypt
| | - Maria Stankiewicz
- Faculty of Biology and Environment Protection, N. Copernicus University, Torun, Poland
| | - Karolina Mikulska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, N. Copernicus University, Torun, Poland
| | - Wieslaw Nowak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, N. Copernicus University, Torun, Poland
| | - Cédric Pennetier
- Institut de Recherche pour le Développement, UMR 224 Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MiVEGEC), Montpellier, France
| | - Mathilde Goulu
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR 4207 QUASAV, Université d’Angers, UFR SCIENCES, Angers cedex, France
| | - Carole Fruchart-Gaillard
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines (SIMOPRO), Laboratoire de Toxinologie Moléculaire et Biotechnologie, Gif sur Yvette, France
| | - Patricia Licznar
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR 4207 QUASAV, Université d’Angers, UFR SCIENCES, Angers cedex, France
| | - Véronique Apaire-Marchais
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR 4207 QUASAV, Université d’Angers, UFR SCIENCES, Angers cedex, France
| | - Olivier List
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR 4207 QUASAV, Université d’Angers, UFR SCIENCES, Angers cedex, France
| | - Vincent Corbel
- Institut de Recherche pour le Développement, UMR 224 Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MiVEGEC), Montpellier, France
- Department of Entomology, Faculty of Agriculture at Kamphaeng Saen, Kamphaeng Saen Campus, Kasetsart University, Nakhon Pathom, Thailand
| | - Denis Servent
- CEA, iBiTecS, Service d’Ingénierie Moléculaire des Protéines (SIMOPRO), Laboratoire de Toxinologie Moléculaire et Biotechnologie, Gif sur Yvette, France
| | - Bruno Lapied
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM) UPRES EA 2647/USC INRA 1330, SFR 4207 QUASAV, Université d’Angers, UFR SCIENCES, Angers cedex, France
- * E-mail:
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Tsitoura P, Koussis K, Iatrou K. Inhibition of Anopheles gambiae odorant receptor function by mosquito repellents. J Biol Chem 2015; 290:7961-72. [PMID: 25657000 PMCID: PMC4367294 DOI: 10.1074/jbc.m114.632299] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/28/2015] [Indexed: 11/06/2022] Open
Abstract
The identification of molecular targets of insect repellents has been a challenging task, with their effects on odorant receptors (ORs) remaining a debatable issue. Here, we describe a study on the effects of selected mosquito repellents, including the widely used repellent N,N-diethyl-meta-toluamide (DEET), on the function of specific ORs of the African malaria vector Anopheles gambiae. This study, which has been based on quantitative measurements of a Ca(2+)-activated photoprotein biosensor of recombinant OR function in an insect cell-based expression platform and a sequential compound addition protocol, revealed that heteromeric OR (ORx/Orco) function was susceptible to strong inhibition by all tested mosquito repellents except DEET. Moreover, our results demonstrated that the observed inhibition was due to efficient blocking of Orco (olfactory receptor coreceptor) function. This mechanism of repellent action, which is reported for the first time, is distinct from the mode of action of other characterized insect repellents including DEET.
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Affiliation(s)
- Panagiota Tsitoura
- From the Insect Molecular Genetics and Biotechnology Group, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", 15310 Athens and
| | - Konstantinos Koussis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Crete, Greece
| | - Kostas Iatrou
- From the Insect Molecular Genetics and Biotechnology Group, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", 15310 Athens and
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62
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Sparks JT, Bohbot JD, Dickens JC. Olfactory Disruption. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 130:81-108. [DOI: 10.1016/bs.pmbts.2014.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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63
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Hodges TK, Cosme LV, Athrey G, Pathikonda S, Takken W, Slotman MA. Species-specific chemosensory gene expression in the olfactory organs of the malaria vector Anopheles gambiae. BMC Genomics 2014; 15:1089. [PMID: 25495232 PMCID: PMC4299676 DOI: 10.1186/1471-2164-15-1089] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 12/04/2014] [Indexed: 01/05/2023] Open
Abstract
Background The malaria mosquito Anopheles gambiae has a high preference for human hosts, a characteristic that contributes greatly to its capacity for transmitting human malaria. A sibling species, An. quadriannulatus, has a quite different host preference and feeds mostly on bovids. For this reason it does not contribute to human malaria transmission. Host seeking in mosquitoes is modulated by the olfactory system, which is primarily housed in the antennae and maxillary palps. Therefore, the detection of differing host odors by sibling species may be reflected in the expression level of the olfactory genes involved. Accordingly, we compared the transcriptomes of the antennae and maxillary palps of An. gambiae and An. quadriannulatus. Results We identified seven relatively abundant olfactory receptors, nine ionotropic receptors and three odorant binding proteins that are substantially up-regulated in An. gambiae antennae. Interestingly, we find that the maxillary palps of An. gambiae contain a species-specific olfactory receptor, Or52, and five An. gambiae-specific gustatory receptors (AgGr48-52) that are relatively abundant. These five gustatory receptors are also expressed in An. gambiae antennae, although at lower level, indicating a likely role in olfaction, rather than gustation. We also document an approximately three-fold higher overall expression of olfaction genes in the maxillary palps of An. quadriannulatus, indicating an important role of this organ in the olfaction system of this species. Finally, the expression of the CO2 receptor genes is five to six-fold higher in the zoophilic An. quadriannulatus, implying a much higher sensitivity for detecting CO2. Conclusions These results identify potential human host preference genes in the malaria vector An. gambiae. Interestingly, species-specific expression of several gustatory receptors in the olfactory organs indicate a role in olfaction rather than gustation. Additionally, a more expansive role for maxillary palps in olfaction is implicated than previously thought, albeit more so in the zoophilic An. quadriannulatus. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1089) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | - Michel A Slotman
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA.
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Pitts RJ, Derryberry SL, Pulous FE, Zwiebel LJ. Antennal-expressed ammonium transporters in the malaria vector mosquito Anopheles gambiae. PLoS One 2014; 9:e111858. [PMID: 25360676 PMCID: PMC4216128 DOI: 10.1371/journal.pone.0111858] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 10/07/2014] [Indexed: 01/13/2023] Open
Abstract
The principal Afrotropical malaria vector mosquito, Anopheles gambiae remains a significant threat to human health. In this anthropophagic species, females detect and respond to a range of human-derived volatile kairomones such as ammonia, lactic acid, and other carboxylic acids in their quest for blood meals. While the molecular underpinnings of mosquito olfaction and host seeking are becoming better understood, many questions remain unanswered. In this study, we have identified and characterized two candidate ammonium transporter genes, AgAmt and AgRh50 that are expressed in the mosquito antenna and may contribute to physiological and behavioral responses to ammonia, which is an important host kairomone for vector mosquitoes. AgAmt transcripts are highly enhanced in female antennae while a splice variant of AgRh50 appears to be antennal-specific. Functional expression of AgAmt in Xenopus laevis oocytes facilitates inward currents in response to both ammonium and methylammonium, while AgRh50 is able to partially complement a yeast ammonium transporter mutant strain, validating their conserved roles as ammonium transporters. We present evidence to suggest that both AgAmt and AgRh50 are in vivo ammonium transporters that are important for ammonia sensitivity in An. gambiae antennae, either by clearing ammonia from the sensillar lymph or by facilitating sensory neuron responses to environmental exposure. Accordingly, AgAmt and AgRh50 represent new and potentially important targets for the development of novel vector control strategies.
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Affiliation(s)
- R. Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Global Health, Nashville, Tennessee, United States of America
| | - Stephen L. Derryberry
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Fadi E. Pulous
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Laurence J. Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Global Health, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt Brain Institute, Program in Developmental Biology and Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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Zhou X, Rinker DC, Pitts RJ, Rokas A, Zwiebel LJ. Divergent and conserved elements comprise the chemoreceptive repertoire of the nonblood-feeding mosquito Toxorhynchites amboinensis. Genome Biol Evol 2014; 6:2883-96. [PMID: 25326137 PMCID: PMC4224357 DOI: 10.1093/gbe/evu231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Many mosquito species serve as vectors of diseases such as malaria and yellow fever, wherein pathogen transmission is tightly associated with the reproductive requirement of taking vertebrate blood meals. Toxorhynchites is one of only three known mosquito genera that does not host-seek and initiates egg development in the absence of a blood-derived protein bolus. These remarkable differences make Toxorhynchites an attractive comparative reference for understanding mosquito chemosensation as it pertains to host-seeking. We performed deep transcriptome profiling of adult female Toxorhynchites amboinensis bodies, antennae and maxillary palps, and identified 25,084 protein-coding “genes” in the de novo assembly. Phylogenomic analysis of 4,266 single-copy “genes” from T. amboinensis, Aedes aegypti, Anopheles gambiae, and Culex quinquefasciatus robustly supported Ae. aegypti as the closest relative of T. amboinensis, with the two species diverged approximately 40 Ma. We identified a large number of T. amboinensis chemosensory “genes,” the majority of which have orthologs in other mosquitoes. Finally, cross-species expression analyses indicated that patterns of chemoreceptor transcript abundance were very similar for chemoreceptors that are conserved between T. amboinensis and Ae. aegypti, whereas T. amboinensis appeared deficient in the variety of expressed, lineage-specific chemoreceptors. Our transcriptome assembly of T. amboinensis represents the first comprehensive genomic resource for a nonblood-feeding mosquito and establishes a foundation for future comparative studies of blood-feeding and nonblood-feeding mosquitoes. We hypothesize that chemosensory genes that display discrete patterns of evolution and abundance between T. amboinensis and blood-feeding mosquitoes are likely to play critical roles in host-seeking and hence the vectorial capacity.
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Affiliation(s)
- Xiaofan Zhou
- Department of Biological Sciences, Vanderbilt University
| | - David C Rinker
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Ronald Jason Pitts
- Department of Biological Sciences, Vanderbilt University Vanderbilt Institute for Global Health, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Laurence J Zwiebel
- Department of Biological Sciences, Vanderbilt University Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee Vanderbilt Institute for Global Health, Vanderbilt University Medical Center, Nashville, Tennessee Department of Pharmacology, Vanderbilt Brain Institute, Program in Developmental Biology and Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee
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Sanford JL, Barski SA, Seen CM, Dickens JC, Shields VDC. Neurophysiological and behavioral responses of gypsy moth larvae to insect repellents: DEET, IR3535, and picaridin. PLoS One 2014; 9:e99924. [PMID: 24955823 PMCID: PMC4067281 DOI: 10.1371/journal.pone.0099924] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 05/20/2014] [Indexed: 11/19/2022] Open
Abstract
The interactions between insect repellents and the olfactory system have been widely studied, however relatively little is known about the effects of repellents on the gustatory system of insects. In this study, we show that the gustatory receptor neuron (GRN) located in the medial styloconic sensilla on the maxillary palps of gypsy moth larvae, and known to be sensitive to feeding deterrents, also responds to the insect repellents DEET, IR3535, and picaridin. These repellents did not elicit responses in the lateral styloconic sensilla. Moreover, behavioral studies demonstrated that each repellent deterred feeding. This is the first study to show perception of insect repellents by the gustatory system of a lepidopteran larva and suggests that detection of a range of bitter or aversive compounds may be a broadly conserved feature among insects.
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Affiliation(s)
- Jillian L. Sanford
- Biological Sciences Department, Insect Morphology and Physiology Lab, Towson University, Towson, Maryland, United States of America
| | - Sharon A. Barski
- Biological Sciences Department, Insect Morphology and Physiology Lab, Towson University, Towson, Maryland, United States of America
| | - Christina M. Seen
- Biological Sciences Department, Insect Morphology and Physiology Lab, Towson University, Towson, Maryland, United States of America
| | - Joseph C. Dickens
- United States Department of Agriculture, Agricultural Research Service, Henry A. Wallace Beltsville Agricultural Research Center, Invasive Insect Biocontrol and Behavior Laboratory, Beltsville, Maryland, United States of America
| | - Vonnie D. C. Shields
- Biological Sciences Department, Insect Morphology and Physiology Lab, Towson University, Towson, Maryland, United States of America
- * E-mail:
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67
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Andersson MN, Videvall E, Walden KKO, Harris MO, Robertson HM, Löfstedt C. Sex- and tissue-specific profiles of chemosensory gene expression in a herbivorous gall-inducing fly (Diptera: Cecidomyiidae). BMC Genomics 2014; 15:501. [PMID: 24948464 PMCID: PMC4230025 DOI: 10.1186/1471-2164-15-501] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/13/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The chemical senses of insects mediate behaviors that are closely linked to survival and reproduction. The order Diptera contains two model organisms, the vinegar fly Drosophila melanogaster and the mosquito Anopheles gambiae, whose chemosensory genes have been extensively studied. Representing a third dipteran lineage with an interesting phylogenetic position, and being ecologically distinct by feeding on plants, the Hessian fly (Mayetiola destructor Say, Diptera: Cecidomyiidae) genome sequence has recently become available. Among plant-feeding insects, the Hessian fly is unusual in 'reprogramming' the plant to create a superior food and in being the target of plant resistance genes, a feature shared by plant pathogens. Chemoreception is essential for reproductive success, including detection of sex pheromone and plant-produced chemicals by males and females, respectively. RESULTS We identified genes encoding 122 odorant receptors (OR), 28 gustatory receptors (GR), 39 ionotropic receptors (IR), 32 odorant binding proteins, and 7 sensory neuron membrane proteins in the Hessian fly genome. We then mapped Illumina-sequenced transcriptome reads to the genome to explore gene expression in male and female antennae and terminal abdominal segments. Our results reveal that a large number of chemosensory genes have up-regulated expression in the antennae, and the expression is in many cases sex-specific. Sex-specific expression is particularly evident among the Or genes, consistent with the sex-divergent olfactory-mediated behaviors of the adults. In addition, the large number of Ors in the genome but the reduced set of Grs and divergent Irs suggest that the short-lived adults rely more on long-range olfaction than on short-range gustation. We also report up-regulated expression of some genes from all chemosensory gene families in the terminal segments of the abdomen, which play important roles in reproduction. CONCLUSIONS We show that a large number of the chemosensory genes in the Hessian fly genome have sex- and tissue-specific expression profiles. Our findings provide the first insights into the molecular basis of chemoreception in plant-feeding flies, representing an important advance toward a more complete understanding of olfaction in Diptera and its links to ecological specialization.
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Affiliation(s)
| | - Elin Videvall
- Department of Biology, Lund University, Lund SE-223 62, Sweden
| | - Kimberly KO Walden
- Department of Entomology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Marion O Harris
- Department of Entomology, North Dakota State University, Fargo, ND 58108-6050, USA
| | - Hugh M Robertson
- Department of Entomology, University of Illinois, Urbana-Champaign, IL 61801, USA
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Dwivedi SB, Muthusamy B, Kumar P, Kim MS, Nirujogi RS, Getnet D, Ahiakonu P, De G, Nair B, Gowda H, Prasad TSK, Kumar N, Pandey A, Okulate M. Brain proteomics of Anopheles gambiae. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2014; 18:421-37. [PMID: 24937107 DOI: 10.1089/omi.2014.0007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Anopheles gambiae has a well-adapted system for host localization, feeding, and mating behavior, which are all governed by neuronal processes in the brain. However, there are no published reports characterizing the brain proteome to elucidate neuronal signaling mechanisms in the vector. To this end, a large-scale mapping of the brain proteome of An. gambiae was carried out using high resolution tandem mass spectrometry, revealing a repertoire of >1800 proteins, of which 15% could not be assigned any function. A large proportion of the identified proteins were predicted to be involved in diverse biological processes including metabolism, transport, protein synthesis, and olfaction. This study also led to the identification of 10 GPCR classes of proteins, which could govern sensory pathways in mosquitoes. Proteins involved in metabolic and neural processes, chromatin modeling, and synaptic vesicle transport associated with neuronal transmission were predominantly expressed in the brain. Proteogenomic analysis expanded our findings with the identification of 15 novel genes and 71 cases of gene refinements, a subset of which were validated by RT-PCR and sequencing. Overall, our study offers valuable insights into the brain physiology of the vector that could possibly open avenues for intervention strategies for malaria in the future.
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Affiliation(s)
- Sutopa B Dwivedi
- 1 Institute of Bioinformatics , International Technology Park, Bangalore, Karnataka, India
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Chen S, Luetje CW. Trace amines inhibit insect odorant receptor function through antagonism of the co-receptor subunit. F1000Res 2014; 3:84. [PMID: 25075297 PMCID: PMC4097363 DOI: 10.12688/f1000research.3825.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/01/2014] [Indexed: 01/05/2023] Open
Abstract
Many insect behaviors are driven by olfaction, making insect olfactory receptors (ORs) appealing targets for insect control. Insect ORs are odorant-gated ion channels, with each receptor thought to be composed of a representative from a large, variable family of odorant binding subunits and a highly conserved co-receptor subunit (Orco), assembled in an unknown stoichiometry. Synthetic Orco directed agonists and antagonists have recently been identified. Several Orco antagonists have been shown to act via an allosteric mechanism to inhibit OR activation by odorants. The high degree of conservation of Orco across insect species results in Orco antagonists having broad activity at ORs from a variety of insect species and suggests that the binding site for Orco ligands may serve as a modulatory site for compounds endogenous to insects or may be a target of exogenous compounds, such as those produced by plants. To test this idea, we screened a series of biogenic and trace amines, identifying several as Orco antagonists. Of particular interest were tryptamine, a plant-produced amine, and tyramine, an amine endogenous to the insect nervous system. Tryptamine was found to be a potent antagonist of Orco, able to block Orco activation by an Orco agonist and to allosterically inhibit activation of ORs by odorants. Tyramine had effects similar to those of tryptamine, but was less potent. Importantly, both tryptamine and tyramine displayed broad activity, inhibiting odorant activation of ORs of species from three different insect orders (Diptera, Lepidoptera and Coleoptera), as well as odorant activation of six diverse ORs from a single species (the human malaria vector mosquito, Anopheles gambiae). Our results suggest that endogenous and exogenous natural compounds serve as Orco ligands modulating insect olfaction and that Orco can be an important target for the development of novel insect repellants.
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Affiliation(s)
- Sisi Chen
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33101, USA
| | - Charles W. Luetje
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33101, USA
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Mysore K, Andrews E, Li P, Duman-Scheel M. Chitosan/siRNA nanoparticle targeting demonstrates a requirement for single-minded during larval and pupal olfactory system development of the vector mosquito Aedes aegypti. BMC DEVELOPMENTAL BIOLOGY 2014; 14:9. [PMID: 24552425 PMCID: PMC3936921 DOI: 10.1186/1471-213x-14-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 02/07/2014] [Indexed: 11/16/2022]
Abstract
Background Essentially nothing is known about the genetic regulation of olfactory system development in vector mosquitoes, which use olfactory cues to detect blood meal hosts. Studies in Drosophila melanogaster have identified a regulatory matrix of transcription factors that controls pupal/adult odorant receptor (OR) gene expression in olfactory receptor neurons (ORNs). However, it is unclear if transcription factors that function in the D. melanogaster regulatory matrix are required for OR expression in mosquitoes. Furthermore, the regulation of OR expression during development of the larval olfactory system, which is far less complex than that of pupae/adults, is not well understood in any insect, including D. melanogaster. Here, we examine the regulation of OR expression in the developing larval olfactory system of Aedes aegypti, the dengue vector mosquito. Results A. aegypti bears orthologs of eight transcription factors that regulate OR expression in D. melanogaster pupae/adults. These transcription factors are expressed in A. aegypti larval antennal sensory neurons, and consensus binding sites for these transcription factors reside in the 5’ flanking regions of A. aegypti OR genes. Consensus binding sites for Single-minded (Sim) are located adjacent to over half the A. aegypti OR genes, suggesting that this transcription factor functions as a major regulator of mosquito OR expression. To functionally test this hypothesis, chitosan/siRNA nanoparticles were used to target sim during larval olfactory development. These experiments demonstrated that Sim positively regulates expression of a large subset of OR genes, including orco, the obligate co-receptor in the assembly and function of heteromeric OR/Orco complexes. Decreased innervation of the antennal lobe was also noted in sim knockdown larvae. These OR expression and antennal lobe defects correlated with a larval odorant tracking behavioral defect. OR expression and antennal lobe defects were also observed in sim knockdown pupae. Conclusions The results of this investigation indicate that Sim has multiple functions during larval and pupal olfactory system development in A. aegypti.
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Affiliation(s)
| | | | | | - Molly Duman-Scheel
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, South Bend, IN 46617, United States of America.
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Pitts RJ, Liu C, Zhou X, Malpartida JC, Zwiebel LJ. Odorant receptor-mediated sperm activation in disease vector mosquitoes. Proc Natl Acad Sci U S A 2014; 111:2566-71. [PMID: 24550284 PMCID: PMC3932880 DOI: 10.1073/pnas.1322923111] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insects, such as the malaria vector mosquito, Anopheles gambiae, depend upon chemoreceptors to respond to volatiles emitted from a range of environmental sources, most notably blood meal hosts and oviposition sites. A subset of peripheral signaling pathways involved in these insect chemosensory-dependent behaviors requires the activity of heteromeric odorant receptor (OR) ion channel complexes and ligands for numerous A. gambiae ORs (AgOrs) have been identified. Although AgOrs are expressed in nonhead appendages, studies characterizing potential AgOr function in nonolfactory tissues have not been conducted. In the present study, we explore the possibility that AgOrs mediate responses of spermatozoa to endogenous signaling molecules in A. gambiae. In addition to finding AgOr transcript expression in testes, we show that the OR coreceptor, AgOrco, is localized to the flagella of A. gambiae spermatozoa where Orco-specific agonists, antagonists, and other odorant ligands robustly activate flagella beating in an Orco-dependent process. We also demonstrate Orco expression and Orco-mediated activation of spermatozoa in the yellow fever mosquito, Aedes aegypti. Moreover, we find Orco localization in testes across distinct insect taxa and posit that OR-mediated responses in spermatozoa may represent a general characteristic of insect reproduction and an example of convergent evolution.
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Affiliation(s)
- R. Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Chao Liu
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Xiaofan Zhou
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Juan C. Malpartida
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Laurence J. Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
- Department of Pharmacology, Vanderbilt Brain Institute, Program in Developmental Biology and Institutes of Chemical Biology and Global Health, Vanderbilt University Medical Center, Nashville, TN 37235
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Chen S, Luetje CW. Phenylthiophenecarboxamide antagonists of the olfactory receptor co-receptor subunit from a mosquito. PLoS One 2013; 8:e84575. [PMID: 24358366 PMCID: PMC3866151 DOI: 10.1371/journal.pone.0084575] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 11/22/2013] [Indexed: 01/04/2023] Open
Abstract
Insects detect environmental chemicals using chemosensory receptors, such as the ORs, a family of odorant-gated ion channels. Insect ORs are multimeric complexes of unknown stoichiometry, formed by a common subunit (the odorant receptor co-receptor subunit, Orco) and one of many variable subunits that confer odorant specificity. The recent discovery of Orco directed ligands, including both agonists and antagonists, suggests Orco as a promising target for chemical control of insects. In addition to competitively inhibiting OR activation by Orco agonists, several Orco antagonists have been shown to act through a non-competitive mechanism to inhibit OR activation by odorants. We previously identified a series of Orco antagonists, including N-(4-ethylphenyl)-2-thiophenecarboxamide (OX1a, previously referred to as OLC20). Here, we explore the chemical space around the OX1a structure to identify more potent Orco antagonists. Cqui\Orco+Cqui\Or21, an OR from Culex quinquefasciatus (the Southern House Mosquito) that responds to 3-methylindole (skatole) and is thought to mediate oviposition behavior, was expressed in Xenopus oocytes and receptor function assayed by two-electrode voltage clamp electrophysiology. 22 structural analogs of OX1a were screened for antagonism of OR activation by an Orco agonist. By varying the moieties decorating the phenyl and thiophene rings, and altering the distance between the rings, we were able to identify antagonists with improved potency. Detailed examination of three of these compounds (N-mesityl-2-thiophenecarboxamide, N-(4-methylbenzyl)-2-thiophenecarboxamide and N-(2-ethylphenyl)-3-(2-thienyl)-2-propenamide) demonstrated competitive inhibition of receptor activation by an Orco agonist and non-competitive inhibition of receptor activation by an odorant. The ability to inhibit OR activation by odorants may be a general property of this class of Orco antagonist, suggesting that odorant mediated behaviors can be manipulated through Orco antagonism. The high conservation of Orco across insect species and previous demonstrations that various Orco ligands are active at ORs derived from several different insect orders suggests that Orco antagonists may have broad applicability.
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Affiliation(s)
- Sisi Chen
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Charles W. Luetje
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
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Rinker DC, Zhou X, Pitts RJ. Antennal transcriptome profiles of anopheline mosquitoes reveal human host olfactory specialization in Anopheles gambiae. BMC Genomics 2013; 14:749. [PMID: 24182346 PMCID: PMC3833343 DOI: 10.1186/1471-2164-14-749] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 10/22/2013] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Two sibling members of the Anopheles gambiae species complex display notable differences in female blood meal preferences. An. gambiae s.s. has a well-documented preference for feeding upon human hosts, whereas An. quadriannulatus feeds on vertebrate/mammalian hosts, with only opportunistic feeding upon humans. Because mosquito host-seeking behaviors are largely driven by the sensory modality of olfaction, we hypothesized that hallmarks of these divergent host seeking phenotypes will be in evidence within the transcriptome profiles of the antennae, the mosquito's principal chemosensory appendage. RESULTS To test this hypothesis, we have sequenced antennal mRNA of non-bloodfed females from each species and observed a number of distinct quantitative and qualitative differences in their chemosensory gene repertoires. In both species, these gene families show higher rates of sequence polymorphisms than the overall rates in their respective transcriptomes, with potentially important divergences between the two species. Moreover, quantitative differences in odorant receptor transcript abundances have been used to model potential distinctions in volatile odor receptivity between the two sibling species of anophelines. CONCLUSION This analysis suggests that the anthropophagic behavior of An. gambiae s.s. reflects the differential distribution of olfactory receptors in the antenna, likely resulting from a co-option and refinement of molecular components common to both species. This study improves our understanding of the molecular evolution of chemoreceptors in closely related anophelines and suggests possible mechanisms that underlie the behavioral distinctions in host seeking that, in part, account for the differential vectorial capacity of these mosquitoes.
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Affiliation(s)
- David C Rinker
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Xiaofan Zhou
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Ronald Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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Odour receptors and neurons for DEET and new insect repellents. Nature 2013; 502:507-12. [PMID: 24089210 PMCID: PMC3927149 DOI: 10.1038/nature12594] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 08/15/2013] [Indexed: 02/04/2023]
Abstract
There are major impediments to finding improved DEET alternatives because the receptors causing olfactory repellency are unknown, and new chemicals require exorbitant costs to determine safety for human use. Here we identify DEET-sensitive neurons in a pit-like structure in the Drosophila melanogaster antenna called the sacculus. They express a highly conserved receptor, Ir40a, and flies in which these neurons are silenced or Ir40a is knocked down lose avoidance to DEET. We used a computational structure-activity screen of >400,000 compounds that identified >100 natural compounds as candidate repellents. We tested several and found that most activate Ir40a(+) neurons and are repellents for Drosophila. These compounds are also strong repellents for mosquitoes. The candidates contain chemicals that do not dissolve plastic, are affordable and smell mildly like grapes, with three considered safe in human foods. Our findings pave the way to discover new generations of repellents that will help fight deadly insect-borne diseases worldwide.
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Liu C, Zwiebel LJ. Molecular characterization of larval peripheral thermosensory responses of the malaria vector mosquito Anopheles gambiae. PLoS One 2013; 8:e72595. [PMID: 23940815 PMCID: PMC3737131 DOI: 10.1371/journal.pone.0072595] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 07/18/2013] [Indexed: 11/18/2022] Open
Abstract
Thermosensation provides vital inputs for the malaria vector mosquito, Anopheles gambiae which utilizes heat-sensitivity within a broad spectrum of behaviors, most notably, the localization of human hosts for blood feeding. In this study, we examine thermosensory behaviors in larval-stage An. gambiae, which as a result of their obligate aquatic habitats and importance for vectorial capacity, represents an opportunistic target for vector control as part of the global campaign to eliminate malaria. As is the case for adults, immature mosquitoes respond differentially to a diverse array of external heat stimuli. In addition, larvae exhibit a striking phenotypic plasticity in thermal-driven behaviors that are established by temperature at which embryonic development occurs. Within this spectrum, RNAi-directed gene-silencing studies provide evidence for the essential role of the Transient Receptor Potential sub-family A1 (TRPA1) channel in mediating larval thermal-induced locomotion and thermal preference within a discrete upper range of ambient temperatures.
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Affiliation(s)
- Chao Liu
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
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76
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Mysore K, Flannery EM, Tomchaney M, Severson DW, Duman-Scheel M. Disruption of Aedes aegypti olfactory system development through chitosan/siRNA nanoparticle targeting of semaphorin-1a. PLoS Negl Trop Dis 2013; 7:e2215. [PMID: 23696908 PMCID: PMC3656119 DOI: 10.1371/journal.pntd.0002215] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/02/2013] [Indexed: 11/19/2022] Open
Abstract
Despite the devastating impact of mosquito-borne illnesses on human health, surprisingly little is known about mosquito developmental biology, including development of the olfactory system, a tissue of vector importance. Analysis of mosquito olfactory developmental genetics has been hindered by a lack of means to target specific genes during the development of this sensory system. In this investigation, chitosan/siRNA nanoparticles were used to target semaphorin-1a (sema1a) during olfactory system development in the dengue and yellow fever vector mosquito Aedes aegypti. Immunohistochemical analyses and anterograde tracing of antennal sensory neurons, which were used to track the progression of olfactory development in this species, revealed antennal lobe defects in sema1a knockdown fourth instar larvae. These findings, which correlated with a larval odorant tracking behavioral phenotype, identified previously unreported roles for Sema1a in the developing insect larval olfactory system. Analysis of sema1a knockdown pupae also revealed a number of olfactory phenotypes, including olfactory receptor neuron targeting and projection neuron defects coincident with a collapse in the structure and shape of the antennal lobe and individual glomeruli. This study, which is to our knowledge the first functional genetic analysis of insect olfactory development outside of D. melanogaster, identified critical roles for Sema1a during Ae. aegypti larval and pupal olfactory development and advocates the use of chitosan/siRNA nanoparticles as an effective means of targeting genes during post-embryonic Ae. aegypti development. Use of siRNA nanoparticle methodology to understand sensory developmental genetics in mosquitoes will provide insight into the evolutionary conservation and divergence of key developmental genes which could be exploited in the development of both common and species-specific means for intervention.
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Affiliation(s)
- Keshava Mysore
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, South Bend, Indiana, United States of America
| | - Ellen M. Flannery
- Eck Institute for Global Health and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Michael Tomchaney
- Eck Institute for Global Health and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - David W. Severson
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, South Bend, Indiana, United States of America
- Eck Institute for Global Health and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Molly Duman-Scheel
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, South Bend, Indiana, United States of America
- Eck Institute for Global Health and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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77
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Rinker DC, Pitts RJ, Zhou X, Suh E, Rokas A, Zwiebel LJ. Blood meal-induced changes to antennal transcriptome profiles reveal shifts in odor sensitivities in Anopheles gambiae. Proc Natl Acad Sci U S A 2013; 110:8260-5. [PMID: 23630291 PMCID: PMC3657813 DOI: 10.1073/pnas.1302562110] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Olfactory-driven behaviors are central to the lifecycle of the malaria vector mosquito Anopheles gambiae and are initiated by peripheral signaling in the antenna and other olfactory tissues. To continue gaining insight into the relationship between gene expression and olfaction, we have performed cohort comparisons of antennal transcript abundances at five time points after a blood meal, a key event in both reproduction and disease transmission cycles. We found that more than 5,000 transcripts displayed significant abundance differences, many of which were correlated by cluster analysis. Within the chemosensory gene families, we observed a general reduction in the level of chemosensory gene transcripts, although a subset of odorant receptors (AgOrs) was modestly enhanced in post-blood-fed samples. Integration of AgOr transcript abundance data with previously characterized AgOr excitatory odorant response profiles revealed potential changes in antennal odorant receptivity that coincided with the shift from host-seeking to oviposition behaviors in blood-fed female mosquitoes. Behavioral testing of ovipositing females to odorants highlighted by this synthetic analysis identified two unique, unitary oviposition cues for An. gambiae, 2-propylphenol and 4-methylcyclohexanol. We posit that modest, yet cumulative, alterations of AgOr transcript levels modulate peripheral odor coding resulting in biologically relevant behavioral effects. Moreover, these results demonstrate that highly quantitative, RNAseq transcript abundance data can be successfully integrated with functional data to generate testable hypotheses.
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Affiliation(s)
- David C. Rinker
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, TN 37235
| | - R. Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Xiaofan Zhou
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Eunho Suh
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Antonis Rokas
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, TN 37235
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
| | - Laurence J. Zwiebel
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, TN 37235
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235; and
- Department of Pharmacology, Vanderbilt Brain Institute, Program in Developmental Biology, and Institutes of Chemical Biology and Global Health, Vanderbilt University Medical Center, Nashville, TN 37235
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78
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Poivet E, Gallot A, Montagné N, Glaser N, Legeai F, Jacquin-Joly E. A comparison of the olfactory gene repertoires of adults and larvae in the noctuid moth Spodoptera littoralis. PLoS One 2013; 8:e60263. [PMID: 23565215 PMCID: PMC3614943 DOI: 10.1371/journal.pone.0060263] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/24/2013] [Indexed: 11/18/2022] Open
Abstract
To better understand the olfactory mechanisms in a lepidopteran pest model species, the cotton leafworm Spodoptera littoralis, we have recently established a partial transcriptome from adult antennae. Here, we completed this transcriptome using next generation sequencing technologies, namely 454 and Illumina, on both adult antennae and larval tissues, including caterpillar antennae and maxillary palps. All sequences were assembled in 77,643 contigs. Their analysis greatly enriched the repertoire of chemosensory genes in this species, with a total of 57 candidate odorant-binding and chemosensory proteins, 47 olfactory receptors, 6 gustatory receptors and 17 ionotropic receptors. Using RT-PCR, we conducted the first exhaustive comparison of olfactory gene expression between larvae and adults in a lepidopteran species. All the 127 candidate olfactory genes were profiled for expression in male and female adult antennae and in caterpillar antennae and maxillary palps. We found that caterpillars expressed a smaller set of olfactory genes than adults, with a large overlap between these two developmental stages. Two binding proteins appeared to be larvae-specific and two others were adult-specific. Interestingly, comparison between caterpillar antennae and maxillary palps revealed numerous organ-specific transcripts, suggesting the complementary involvement of these two organs in larval chemosensory detection. Adult males and females shared the same set of olfactory transcripts, except two male-specific candidate pheromone receptors, two male-specific and two female-specific odorant-binding proteins. This study identified transcripts that may be important for sex-specific or developmental stage-specific chemosensory behaviors.
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Affiliation(s)
- Erwan Poivet
- INRA, UMR 1272, Physiologie de l’Insecte, Signalisation et Communication, Versailles, France
| | - Aurore Gallot
- INRA, UMR 1272, Physiologie de l’Insecte, Signalisation et Communication, Versailles, France
- IRISA, Équipe GenScale, Campus Universitaire de Beaulieu, Rennes, France
| | - Nicolas Montagné
- UPMC - Université Paris 6, UMR 1272, Physiologie de l’Insecte, Signalisation et Communication, Paris, France
| | - Nicolas Glaser
- INRA, UMR 1272, Physiologie de l’Insecte, Signalisation et Communication, Versailles, France
| | - Fabrice Legeai
- IRISA, Équipe GenScale, Campus Universitaire de Beaulieu, Rennes, France
| | - Emmanuelle Jacquin-Joly
- INRA, UMR 1272, Physiologie de l’Insecte, Signalisation et Communication, Versailles, France
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79
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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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80
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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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81
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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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82
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Bohbot JD, Dickens JC. Selectivity of odorant receptors in insects. Front Cell Neurosci 2012; 6:29. [PMID: 22811659 PMCID: PMC3396151 DOI: 10.3389/fncel.2012.00029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 06/26/2012] [Indexed: 11/13/2022] Open
Abstract
Insect olfactory receptors (ORs) detect chemicals, shape neuronal physiology, and regulate behavior. Although ORs have been categorized as "generalists" and "specialists" based on their ligand spectrum, both electrophysiological studies and recent pharmacological investigations show that ORs specifically recognize non-pheromonal compounds, and that our understanding of odorant-selectivity mirrors our knowledge of insect chemical ecology. As we are progressively becoming aware that ORs are activated through a variety of mechanisms, the molecular basis of odorant-selectivity and the corollary notion of broad-tuning need to be re-examined from a pharmacological and evolutionary perspective.
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Affiliation(s)
| | - Joseph C. Dickens
- Invasive Insect Biocontrol and Behavior Laboratory, Plant Sciences Institute, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville,MD, USA
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83
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Scialò F, Hansson BS, Giordano E, Polito CL, Digilio FA. Molecular and functional characterization of the odorant receptor2 (OR2) in the tiger mosquito Aedes albopictus. PLoS One 2012; 7:e36538. [PMID: 22606270 PMCID: PMC3351472 DOI: 10.1371/journal.pone.0036538] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 04/09/2012] [Indexed: 12/04/2022] Open
Abstract
In mosquitoes, the olfactory system plays a crucial role in many types of behavior, including nectar feeding, host preference selection and oviposition. Aedes albopictus, known also as the tiger mosquito, is an anthropophilic species, which in the last few years, due to its strong ecological plasticity, has spread throughout the world. Although long considered only a secondary vector of viruses, the potential of its vector capacity may constitute a threat to public health. Based on the idea that an improved understanding of the olfactory system of mosquitoes may assist in the development of control methods that interfere with their behavior, we have undertaken a study aimed at characterizing the A. albopictus Odorant Receptors. Here we report the identification, cloning and functional characterization of the AalOR2 ortholog, that represents the first candidate member of the odorant receptor (OR) family of proteins from A. albopictus. AalOR2 is expressed in the larval heads and antennae of adults. Our data indicate that A. albopictus OR2 (AalOR2) shares a high degree of identity with other mosquito OR2 orthologs characterized to date, confirming that OR2 is one of the most conserved mosquito ORs. Our data indicate that AalOR2 is narrowly tuned to indole, and inhibited by (-)-menthone. In agreement with this results, these two compounds elicit two opposite effects on the olfactory-based behavior of A. albopictus larvae, as determined through a larval behavioral assay. In summary, this work has led to the cloning and de-orphaning of the first Odorant Receptor in the tiger mosquito A. albopictus. In future control strategies this receptor may be used as a potential molecular target.
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MESH Headings
- Aedes/genetics
- Aedes/physiology
- Amino Acid Sequence
- Animals
- Animals, Genetically Modified
- Base Sequence
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Calcium/metabolism
- Cloning, Molecular
- Drosophila/genetics
- Drosophila/metabolism
- Female
- Gene Expression Profiling
- Genes, Insect
- HEK293 Cells
- Humans
- Indoles/pharmacology
- Insect Proteins/genetics
- Insect Proteins/physiology
- Larva/drug effects
- Larva/genetics
- Larva/metabolism
- Male
- Menthol/pharmacology
- Molecular Sequence Data
- Odorants
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Odorant/genetics
- Receptors, Odorant/physiology
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Sequence Homology, Amino Acid
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Affiliation(s)
- Filippo Scialò
- Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy
| | - Bill S. Hansson
- Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology Jena, Germany
| | - Ennio Giordano
- Department of Biological Sciences, University of Naples Federico II, Naples, Italy
| | - Catello L. Polito
- Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy
- Department of Biological Sciences, University of Naples Federico II, Naples, Italy
| | - F. Anna Digilio
- Institute of Genetics and Biophysics A. Buzzati-Traverso, CNR, Naples, Italy
- * E-mail:
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84
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Chen S, Luetje CW. Identification of new agonists and antagonists of the insect odorant receptor co-receptor subunit. PLoS One 2012; 7:e36784. [PMID: 22590607 PMCID: PMC3348135 DOI: 10.1371/journal.pone.0036784] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 04/13/2012] [Indexed: 11/18/2022] Open
Abstract
Background Insects detect attractive and aversive chemicals using several families of chemosensory receptors, including the OR family of olfactory receptors, making these receptors appealing targets for the control of insects. Insect ORs are odorant-gated ion channels, comprised of at least one common subunit (the odorant receptor co-receptor subunit, Orco) and at least one variable odorant specificity subunit. Each of the many ORs of an insect species is activated or inhibited by an unique set of odorants that interact with the variable odorant specificity subunits, making the development of OR directed insect control agents complex and laborious. However, several N-,2-substituted triazolothioacetamide compounds (VUAA1, VU0450667 and VU0183254) were recently shown to act directly on the highly conserved Orco subunit, suggesting that broadly active compounds can be developed. We have explored the chemical space around the VUAA1 structure in order to identify new Orco ligands. Principal Findings We screened ORs from several insect species, using heterologous expression in Xenopus oocytes and an electrophysiological assay, with a panel of 22 compounds structurally related to VUAA1. By varying the nitrogen position in the pyridine ring and altering the moieties decorating the phenyl ring, we identified two new agonists and a series of competitive antagonists. Screening smaller compounds, similar to portions of the VUAA1 structure, also yielded competitive antagonists. Importantly, we show that Orco antagonists inhibit odorant activation of ORs from several insect species. Detailed examination of one antagonist demonstrated inhibition to be through a non-competitive mechanism. Conclusions A similar pattern of agonist and antagonist sensitivity displayed by Orco subunits from different species suggests a highly conserved binding site structure. The susceptibility to inhibition of odorant activation by Orco antagonism is conserved across disparate insect species, suggesing the ligand binding site on Orco as a promising target for the development of novel, broadly active insect repellants.
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Affiliation(s)
- Sisi Chen
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Charles W. Luetje
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- * E-mail:
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85
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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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86
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Rinker DC, Jones PL, Pitts RJ, Rutzler M, Camp G, Sun L, Xu P, Weaver D, Zwiebel LJ. Novel high-throughput screens of Anopheles gambiae odorant receptors reveal candidate behaviour-modifying chemicals for mosquitoes. PHYSIOLOGICAL ENTOMOLOGY 2012; 37:33-41. [PMID: 32255891 PMCID: PMC7123412 DOI: 10.1111/j.1365-3032.2011.00821.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Despite many decades of multilateral global efforts, a significant portion of the world population continues to be plagued with one or more mosquito-vectored diseases. These include malaria and filariasis as well as numerous arboviral-associated illnesses including Dengue and Yellow fevers. The dynamics of disease transmission by mosquitoes is complex, and involves both vector competence and vectorial capacity. One area of intensive effort is the study of chemosensory-driven behaviours in the malaria vector mosquito Anopheles gambiae Giles, the modulation of which are likely to provide opportunities for disease reduction. In this context recent studies have characterized a large divergent family of An. gambiae odorant receptors (AgORs) that play critical roles in olfactory signal transduction. This work has facilitated high-throughput, cell-based calcium mobilization screens of AgOR-expressing HEK cells that have identified a large number of conventional AgOR ligands, as well as the first non-conventional Orco (olfactory receptor co-receptor) family agonist. As such, ligand-mediated modulation serves as a proof-of-concept demonstration that AgORs represent viable targets for high-throughput screening and for the eventual development of behaviour-modifying olfactory compounds. Such attractants or repellents could foster malaria reduction programmes.
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Affiliation(s)
- David C. Rinker
- Center for Human Genetics Training Program, Vanderbilt University Medical Centre, Nashville, U.S.A
| | - Patrick L. Jones
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
| | - R. Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
| | - Michael Rutzler
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
| | - Gray Camp
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
| | - Lujuan Sun
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
| | - Pingxi Xu
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
| | - David Weaver
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, U.S.A
| | - Laurence J Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, U.S.A
- Department of Pharmacology, Vanderbilt University Medical Centre, Nashville, U.S.A
- Center for Molecular Neuroscience, Institute of Global Health and Program in Developmental Biology, Vanderbilt University Medical Centre, Nashville, U.S.A
- Center for Human Genetics Training Program, Vanderbilt University Medical Centre, Nashville, U.S.A
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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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Pask GM, Jones PL, Rützler M, Rinker DC, Zwiebel LJ. Heteromeric Anopheline odorant receptors exhibit distinct channel properties. PLoS One 2011; 6:e28774. [PMID: 22174894 PMCID: PMC3235152 DOI: 10.1371/journal.pone.0028774] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 11/15/2011] [Indexed: 11/30/2022] Open
Abstract
Background Insect odorant receptors (ORs) function as odorant-gated ion channels consisting of a conventional, odorant-binding OR and the Orco coreceptor. While Orco can function as a homomeric ion channel, the role(s) of the conventional OR in heteromeric OR complexes has largely focused only on odorant recognition. Results To investigate other roles of odorant-binding ORs, we have employed patch clamp electrophysiology to investigate the properties of the channel pore of several OR complexes formed by a range of different odorant-specific Anopheles gambiae ORs (AgOrs) each paired with AgOrco. These studies reveal significant differences in cation permeability and ruthenium red susceptibility among different AgOr complexes. Conclusions With observable differences in channel function, the data support a model in which the odorant-binding OR also affects the channel pore. The variable effect contributed by the conventional OR on the conductive properties of odorant-gated sensory channels adds additional complexity to insect olfactory signaling, with differences in odor coding beginning with ORs on the periphery of the olfactory system.
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Affiliation(s)
- Gregory M. Pask
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Patrick L. Jones
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Michael Rützler
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, Aarhus C, Denmark
| | - David C. Rinker
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Laurence J. Zwiebel
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Centers for Molecular Neuroscience and Human Genetics Research, Institutes of Chemical Biology and Global Health and Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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89
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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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90
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A natural polymorphism alters odour and DEET sensitivity in an insect odorant receptor. Nature 2011; 478:511-4. [PMID: 21937991 PMCID: PMC3203342 DOI: 10.1038/nature10438] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 08/08/2011] [Indexed: 02/03/2023]
Abstract
Blood-feeding insects such as mosquitoes are efficient vectors of human infectious diseases because they are strongly attracted by body heat, carbon dioxide and odours produced by their vertebrate hosts. Insect repellents containing DEET (N,N-diethyl-meta-toluamide) are highly effective, but the mechanism by which this chemical wards off biting insects remains controversial despite decades of investigation. DEET seems to act both at close range as a contact chemorepellent, by affecting insect gustatory receptors, and at long range, by affecting the olfactory system. Two opposing mechanisms for the observed behavioural effects of DEET in the gas phase have been proposed: that DEET interferes with the olfactory system to block host odour recognition and that DEET actively repels insects by activating olfactory neurons that elicit avoidance behaviour. Here we show that DEET functions as a modulator of the odour-gated ion channel formed by the insect odorant receptor complex. The functional insect odorant receptor complex consists of a common co-receptor, ORCO (ref. 15) (formerly called OR83B; ref. 16), and one or more variable odorant receptor subunits that confer odour selectivity. DEET acts on this complex to potentiate or inhibit odour-evoked activity or to inhibit odour-evoked suppression of spontaneous activity. This modulation depends on the specific odorant receptor and the concentration and identity of the odour ligand. We identify a single amino-acid polymorphism in the second transmembrane domain of receptor OR59B in a Drosophila melanogaster strain from Brazil that renders OR59B insensitive to inhibition by the odour ligand and modulation by DEET. Our data indicate that natural variation can modify the sensitivity of an odour-specific insect odorant receptor to odour ligands and DEET. Furthermore, they support the hypothesis that DEET acts as a molecular 'confusant' that scrambles the insect odour code, and provide a compelling explanation for the broad-spectrum efficacy of DEET against multiple insect species.
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91
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George J, Blanford S, Domingue MJ, Thomas MB, Read AF, Baker TC. Reduction in host-finding behaviour in fungus-infected mosquitoes is correlated with reduction in olfactory receptor neuron responsiveness. Malar J 2011; 10:219. [PMID: 21812944 PMCID: PMC3162589 DOI: 10.1186/1475-2875-10-219] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 08/03/2011] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Chemical insecticides against mosquitoes are a major component of malaria control worldwide. Fungal entomopathogens formulated as biopesticides and applied as insecticide residual sprays could augment current control strategies and mitigate the evolution of resistance to chemical-based insecticides. METHODS Anopheles stephensi mosquitoes were exposed to Beauveria bassiana or Metarhizium acridum fungal spores and sub-lethal effects of exposure to fungal infection were studied, especially the potential for reductions in feeding and host location behaviours related to olfaction. Electrophysiological techniques, such as electroantennogram, electropalpogram and single sensillum recording techniques were then employed to investigate how fungal exposure affected the olfactory responses in mosquitoes. RESULTS Exposure to B. bassiana caused significant mortality and reduced the propensity of mosquitoes to respond and fly to a feeding stimulus. Exposure to M. acridum spores induced a similar decline in feeding propensity, albeit more slowly than B. bassiana exposure. Reduced host-seeking responses following fungal exposure corresponded to reduced olfactory neuron responsiveness in both antennal electroantennogram and maxillary palp electropalpogram recordings. Single cell recordings from neurons on the palps confirmed that fungal-exposed behavioural non-responders exhibited significantly impaired responsiveness of neurons tuned specifically to 1-octen-3-ol and to a lesser degree, to CO2. CONCLUSIONS Fungal infection reduces the responsiveness of mosquitoes to host odour cues, both behaviourally and neuronally. These pre-lethal effects are likely to synergize with fungal-induced mortality to further reduce the capacity of mosquito populations exposed to fungal biopesticides to transmit malaria.
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Affiliation(s)
- Justin George
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Simon Blanford
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA
| | - Michael J Domingue
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Matthew B Thomas
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA
| | - Andrew F Read
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA
| | - Thomas C Baker
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
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Abstract
Great progress has been made in the field of insect olfaction in recent years. Receptors, neurons, and circuits have been defined in considerable detail, and the mechanisms by which they detect, encode, and process sensory stimuli are being unraveled. We provide a guide to recent progress in the field, with special attention to advances made in the genetic model organism Drosophila. We highlight key questions that merit additional investigation. We then present our view of how recent advances may be applied to the control of disease-carrying insects such as mosquitoes, which transmit disease to hundreds of millions of people each year. We suggest how progress in defining the basic mechanisms of insect olfaction may lead to means of disrupting host-seeking and other olfactory behaviors, thereby reducing the transmission of deadly diseases.
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93
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Pitts RJ, Rinker DC, Jones PL, Rokas A, Zwiebel LJ. Transcriptome profiling of chemosensory appendages in the malaria vector Anopheles gambiae reveals tissue- and sex-specific signatures of odor coding. BMC Genomics 2011; 12:271. [PMID: 21619637 PMCID: PMC3126782 DOI: 10.1186/1471-2164-12-271] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 05/27/2011] [Indexed: 11/10/2022] Open
Abstract
Background Chemosensory signal transduction guides the behavior of many insects, including Anopheles gambiae, the major vector for human malaria in sub-Saharan Africa. To better understand the molecular basis of mosquito chemosensation we have used whole transcriptome RNA sequencing (RNA-seq) to compare transcript expression profiles between the two major chemosensory tissues, the antennae and maxillary palps, of adult female and male An. gambiae. Results We compared chemosensory tissue transcriptomes to whole body transcriptomes of each sex to identify chemosensory enhanced genes. In the six data sets analyzed, we detected expression of nearly all known chemosensory genes and found them to be highly enriched in both olfactory tissues of males and females. While the maxillary palps of both sexes demonstrated strict chemosensory gene expression overlap, we observed acute differences in sensory specialization between male and female antennae. The relatively high expression levels of chemosensory genes in the female antennae reveal its role as an organ predominately assigned to chemosensation. Remarkably, the expression of these genes was highly conserved in the male antennae, but at much lower relative levels. Alternatively, consistent with a role in mating, the male antennae displayed significant enhancement of genes involved in audition, while the female enhancement of these genes was observed, but to a lesser degree. Conclusions These findings suggest that the chemoreceptive spectrum, as defined by gene expression profiles, is largely similar in female and male An. gambiae. However, assuming sensory receptor expression levels are correlated with sensitivity in each case, we posit that male and female antennae are perceptive to the same stimuli, but possess inverse receptive prioritizations and sensitivities. Here we have demonstrated the use of RNA-seq to characterize the sensory specializations of an important disease vector and grounded future studies investigating chemosensory processes.
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Affiliation(s)
- R Jason Pitts
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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94
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Crespo JG. A review of chemosensation and related behavior in aquatic insects. JOURNAL OF INSECT SCIENCE (ONLINE) 2011; 11:62. [PMID: 21864156 PMCID: PMC3281456 DOI: 10.1673/031.011.6201] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 09/13/2010] [Indexed: 05/31/2023]
Abstract
Insects that are secondarily adapted to aquatic environments are able to sense odors from a diverse array of sources. The antenna of these insects, as in all insects, is the main chemosensory structure and its input to the brain allows for integration of sensory information that ultimately ends in behavioral responses. Only a fraction of the aquatic insect orders have been studied with respect to their sensory biology and most of the work has centered either on the description of the different types of sensilla, or on the behavior of the insect as a whole. In this paper, the literature is exhaustively reviewed and ways in which antennal morphology, brain structure, and associated behavior can advance better understanding of the neurobiology involved in processing of chemosensory information are discussed. Moreover, the importance of studying such group of insects is stated, and at the same time it is shown that many interesting questions regarding olfactory processing can be addressed by looking into the changes that aquatic insects undergo when leaving their aquatic environment.
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Affiliation(s)
- José G Crespo
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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95
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Glatz R, Bailey-Hill K. Mimicking nature's noses: from receptor deorphaning to olfactory biosensing. Prog Neurobiol 2010; 93:270-96. [PMID: 21130137 DOI: 10.1016/j.pneurobio.2010.11.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 11/09/2010] [Accepted: 11/22/2010] [Indexed: 12/21/2022]
Abstract
The way in which organisms detect specific volatile compounds within their environment, and the associated neural processing which produces perception and subsequent behavioural responses, have been of interest to scientists for decades. Initially, most olfaction research was conducted using electrophysiological techniques on whole animals. However, the discovery of genes encoding the family of human olfactory receptors (ORs) paved the way for the development of a range of cellular assays, primarily used to deorphan ORs from mammals and insects. These assays have greatly advanced our knowledge of the molecular basis of olfaction, however, while there is currently good agreement on vertebrate and nematode olfactory signalling cascades, debate still surrounds the signalling mechanisms in insects. The inherent specificity and sensitivity of ORs makes them prime candidates as biological detectors of volatile ligands within biosensor devices, which have many potential applications. In the previous decade, researchers have investigated various technologies for transducing OR:ligand interactions into a readable format and thereby produce an olfactory biosensor (or bioelectronic nose) that maintains the discriminating power of the ORs in vivo. Here we review and compare the molecular mechanisms of olfaction in vertebrates and invertebrates, and also summarise the assay technologies utilising sub-tissue level sensing elements (cells and cell extracts), which have been applied to OR deorphanization and biosensor research. Although there are currently no commercial, "field-ready" olfactory biosensors of the kind discussed here, there have been several technological proof-of-concept studies suggesting that we will see their emergence within the next decade.
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Affiliation(s)
- Richard Glatz
- South Australian Research and Development Institute (SARDI), Entomology, GPO Box 397, Adelaide 5001, Australia.
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96
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Tsitoura P, Andronopoulou E, Tsikou D, Agalou A, Papakonstantinou MP, Kotzia GA, Labropoulou V, Swevers L, Georgoussi Z, Iatrou K. Expression and membrane topology of Anopheles gambiae odorant receptors in lepidopteran insect cells. PLoS One 2010; 5:e15428. [PMID: 21082026 PMCID: PMC2972716 DOI: 10.1371/journal.pone.0015428] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 09/21/2010] [Indexed: 12/21/2022] Open
Abstract
A lepidopteran insect cell-based expression system has been employed to express three Anopheles gambiae odorant receptors (ORs), OR1 and OR2, which respond to components of human sweat, and OR7, the ortholog of Drosophila's OR83b, the heteromerization partner of all functional ORs in that system. With the aid of epitope tagging and specific antibodies, efficient expression of all ORs was demonstrated and intrinsic properties of the proteins were revealed. Moreover, analysis of the orientation of OR1 and OR2 on the cellular plasma membrane through the use of a novel ‘topology screen’ assay and FACS analysis demonstrates that, as was recently reported for the ORs in Drosophila melanogaster, mosquito ORs also have a topology different than their mammalian counterparts with their N-terminal ends located in the cytoplasm and their C-terminal ends facing outside the cell. These results set the stage for the production of mosquito ORs in quantities that should permit their detailed biochemical and structural characterization and the exploration of their functional properties.
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Affiliation(s)
- Panagiota Tsitoura
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Evi Andronopoulou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Daniela Tsikou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Adamantia Agalou
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Maria P. Papakonstantinou
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Georgia A. Kotzia
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Vassiliki Labropoulou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Zafiroula Georgoussi
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Kostas Iatrou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
- * E-mail:
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97
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Bohbot JD, Jones PL, Wang G, Pitts RJ, Pask GM, Zwiebel LJ. Conservation of indole responsive odorant receptors in mosquitoes reveals an ancient olfactory trait. Chem Senses 2010; 36:149-60. [PMID: 20956733 DOI: 10.1093/chemse/bjq105] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Aedes aegypti and Anopheles gambiae are among the best-characterized mosquito species within the Culicinae and Anophelinae mosquito clades which diverged ∼150 million years ago. Despite this evolutionary distance, the olfactory systems of these mosquitoes exhibit similar morphological and physiological adaptations. Paradoxically, mosquito odorant receptors, which lie at the heart of chemosensory signal transduction pathways, belong to a large and highly divergent gene family. We have used 2 heterologous expression systems to investigate the functional characteristics of a highly conserved subset of Ors between Ae. aegypti and An. gambiae to investigate whether protein homology correlates with odorant-induced activation. We find that these receptors share similar odorant response profiles and that indole, a common and ecologically relevant olfactory cue, elicits strong responses from these homologous receptors. The identification of other highly conserved members of this Or clade from mosquito species of varying phylogenetic relatedness supports a model in which high sensitivity to indole represents an ancient ecological adaptation that has been preserved as a result of its life cycle importance. These results provide an understanding of how similarities and disparities among homologous OR proteins relate to olfactory function, which can lead to greater insights into the design of successful strategies for the control of mosquito-borne diseases.
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Affiliation(s)
- Jonathan D Bohbot
- Department of Biological Sciences and Pharmacology, Center for Molecular Neuroscience, Programs in Developmental Biology & Genetics, Institutes for Chemical Biology & Global Health, Vanderbilt University, Nashville, TN 37235, USA
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98
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Liu C, Pitts RJ, Bohbot JD, Jones PL, Wang G, Zwiebel LJ. Distinct olfactory signaling mechanisms in the malaria vector mosquito Anopheles gambiae. PLoS Biol 2010; 8. [PMID: 20824161 PMCID: PMC2930861 DOI: 10.1371/journal.pbio.1000467] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 07/19/2010] [Indexed: 11/18/2022] Open
Abstract
Anopheles gambiae is the principal Afrotropical vector for human malaria, in which olfaction mediates a wide range of both adult and larval behaviors. Indeed, mosquitoes depend on the ability to respond to chemical cues for feeding, host preference, and mate location/selection. Building upon previous work that has characterized a large family of An. gambiae odorant receptors (AgORs), we now use behavioral analyses and gene silencing to examine directly the role of AgORs, as well as a newly identified family of candidate chemosensory genes, the An. gambiae variant ionotropic receptors (AgIRs), in the larval olfactory system. Our results validate previous studies that directly implicate specific AgORs in behavioral responses to DEET as well as other odorants and reveal the existence of at least two distinct olfactory signaling pathways that are active in An. gambiae. One system depends directly on AgORs; the other is AgOR-independent and requires the expression and activity of AgIRs. In addition to clarifying the mechanistic basis for olfaction in this system, these advances may ultimately enhance the development of vector control strategies, targeting olfactory pathways in mosquitoes to reduce the catastrophic effects of malaria and other mosquito-borne diseases.
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Affiliation(s)
- Chao Liu
- Departments of Biological Sciences and Pharmacology, Center for Molecular Neuroscience, Institutes of Chemical Biology and Global Health and Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - R. Jason Pitts
- Departments of Biological Sciences and Pharmacology, Center for Molecular Neuroscience, Institutes of Chemical Biology and Global Health and Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Jonathan D. Bohbot
- USDA, Agricultural Research Service, Henry A. Wallace Beltsville Agricultural Research Center, Plant Sciences Institute, Invasive Insect Biocontrol and Behavior Laboratory, Beltsville, Maryland, United States of America
| | - Patrick L. Jones
- Departments of Biological Sciences and Pharmacology, Center for Molecular Neuroscience, Institutes of Chemical Biology and Global Health and Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Guirong Wang
- Departments of Biological Sciences and Pharmacology, Center for Molecular Neuroscience, Institutes of Chemical Biology and Global Health and Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Laurence J. Zwiebel
- Departments of Biological Sciences and Pharmacology, Center for Molecular Neuroscience, Institutes of Chemical Biology and Global Health and Program in Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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99
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Bohbot JD, Dickens JC. Insect repellents: modulators of mosquito odorant receptor activity. PLoS One 2010; 5:e12138. [PMID: 20725637 PMCID: PMC2920324 DOI: 10.1371/journal.pone.0012138] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 07/21/2010] [Indexed: 11/18/2022] Open
Abstract
Background DEET, 2-undecanone (2-U), IR3535 and Picaridin are widely used as insect repellents to prevent interactions between humans and many arthropods including mosquitoes. Their molecular action has only recently been studied, yielding seemingly contradictory theories including odorant-dependent inhibitory and odorant-independent excitatory activities on insect olfactory sensory neurons (OSNs) and odorant receptor proteins (ORs). Methodology/Principal Findings Here we characterize the action of these repellents on two Aedes aegypti ORs, AaOR2 and AaOR8, individually co-expressed with the common co-receptor AaOR7 in Xenopus oocytes; these ORs are respectively activated by the odors indole (AaOR2) and (R)-(−)-1-octen3-ol (AaOR8), odorants used to locate oviposition sites and host animals. In the absence of odorants, DEET activates AaOR2 but not AaOR8, while 2-U activates AaOR8 but not AaOR2; IR3535 and Picaridin do not activate these ORs. In the presence of odors, DEET strongly inhibits AaOR8 but not AaOR2, while 2-U strongly inhibits AaOR2 but not AaOR8; IR3535 and Picaridin strongly inhibit both ORs. Conclusions/Significance These data demonstrate that repellents can act as olfactory agonists or antagonists, thus modulating OR activity, bringing concordance to conflicting models.
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Affiliation(s)
- Jonathan D. Bohbot
- Invasive Insect Biocontrol and Behavior Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Plant Sciences Institute, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States of America
| | - Joseph C. Dickens
- Invasive Insect Biocontrol and Behavior Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Plant Sciences Institute, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States of America
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Pelletier J, Hughes DT, Luetje CW, Leal WS. An odorant receptor from the southern house mosquito Culex pipiens quinquefasciatus sensitive to oviposition attractants. PLoS One 2010; 5:e10090. [PMID: 20386699 PMCID: PMC2851645 DOI: 10.1371/journal.pone.0010090] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 03/18/2010] [Indexed: 12/01/2022] Open
Abstract
Background Insect odorant receptors (ORs) are heteromers comprised of highly variable odorant-binding subunits associated with one conserved co-receptor. They are potential molecular targets for the development of novel mosquito attractants and repellents. ORs have been identified in the malaria mosquito, Anopheles gambiae, and in the yellow fever mosquito, Aedes aegypti. However, they are still unknown in the Southern house mosquito, Culex quinquefasciatus, which transmits pathogens that cause human diseases throughout the world, including West Nile Virus in the United States. Methodology We have employed a combination of bioinformatics, molecular cloning and electrophysiology approaches to identify and characterize the response profile of an OR in Cx. quinquefasciatus. First, we have unveiled a large multigenic family of one-hundred-fifty-eight putative ORs in this species, including a subgroup of conserved ORs in three mosquito species. Using the Xenopus oocytes expression system, we have determined the response profile of CquiOR2, an antennae-specific OR, which shares high identity with putative orthologs in Anopheles gambiae (AgamOR2) and Aedes aegypti (AaegOR2). Conclusion We show that CquiOR2 is highly sensitive to indole, an oviposition attractant for Cx. quinquefasciatus. The response profile of CquiOR2 expressed in Xenopus oocytes resembles that of an olfactory receptor neuron housed in the antennal short blunt-tipped sensilla (A2) of Cx. quinquefasciatus, which are natural detectors for oviposition attractants. This first Culex OR de-orphanized is, therefore, a potential molecular target for screening oviposition attractants.
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Affiliation(s)
- Julien Pelletier
- Department of Entomology, University of California Davis, Davis, California, United States of America
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