1
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Walker SR, Peña-Garcia M, Devineni AV. Connectomic analysis of taste circuits in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.14.613080. [PMID: 39314399 PMCID: PMC11419157 DOI: 10.1101/2024.09.14.613080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Our sense of taste is critical for regulating food consumption. The fruit fly Drosophila represents a highly tractable model to investigate mechanisms of taste processing, but taste circuits beyond sensory neurons are largely unidentified. Here, we use a whole-brain connectome to investigate the organization of Drosophila taste circuits. We trace pathways from four populations of sensory neurons that detect different taste modalities and project to the subesophageal zone (SEZ). We find that second-order taste neurons are primarily located within the SEZ and largely segregated by taste modality, whereas third-order neurons have more projections outside the SEZ and more overlap between modalities. Taste projections out of the SEZ innervate regions implicated in feeding, olfactory processing, and learning. We characterize interconnections between taste pathways, identify modality-dependent differences in taste neuron properties, and use computational simulations to relate connectivity to predicted activity. These studies provide insight into the architecture of Drosophila taste circuits.
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Affiliation(s)
- Sydney R Walker
- Department of Biology, Emory University, Atlanta GA 30322
- These authors contributed equally
| | - Marco Peña-Garcia
- Neuroscience Graduate Program, Emory University, Atlanta GA 30322
- These authors contributed equally
| | - Anita V Devineni
- Department of Biology, Emory University, Atlanta GA 30322
- Neuroscience Graduate Program, Emory University, Atlanta GA 30322
- Lead contact
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2
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Parkinson RH, Scott J, Dorling AL, Jones H, Haslam M, McDermott-Roberts AE, Wright GA. Mouthparts of the bumblebee ( Bombus terrestris) exhibit poor acuity for the detection of pesticides in nectar. eLife 2023; 12:RP89129. [PMID: 38109195 PMCID: PMC10727498 DOI: 10.7554/elife.89129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023] Open
Abstract
Bees are important pollinators of agricultural crops, but their populations are at risk when pesticides are used. One of the largest risks bees face is poisoning of floral nectar and pollen by insecticides. Studies of bee detection of neonicotinoids have reported contradictory evidence about whether bees can taste these pesticides in sucrose solutions and hence avoid them. Here, we use an assay for the detection of food aversion combined with single-sensillum electrophysiology to test whether the mouthparts of the buff-tailed bumblebee (Bombus terrestris) detect the presence of pesticides in a solution that mimicked the nectar of oilseed rape (Brassica napus). Bees did not avoid consuming solutions containing concentrations of imidacloprid, thiamethoxam, clothianidin, or sulfoxaflor spanning six orders of magnitude, even when these solutions contained lethal doses. Only extremely high concentrations of the pesticides altered spiking in gustatory neurons through a slight reduction in firing rate or change in the rate of adaptation. These data provide strong evidence that bumblebees cannot detect or avoid field-relevant concentrations of pesticides using information from their mouthparts. As bees rarely contact floral nectar with other body parts, we predict that they are at high risk of unwittingly consuming pesticides in the nectar of pesticide-treated crops.
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Affiliation(s)
| | - Jennifer Scott
- Department of Biology, University of OxfordOxfordUnited Kingdom
| | - Anna L Dorling
- Department of Biology, University of OxfordOxfordUnited Kingdom
| | - Hannah Jones
- Department of Life Sciences, Imperial CollegeLondonUnited Kingdom
| | - Martha Haslam
- Department of Biology, University of OxfordOxfordUnited Kingdom
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3
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King BH, Gunathunga PB. Gustation in insects: taste qualities and types of evidence used to show taste function of specific body parts. JOURNAL OF INSECT SCIENCE (ONLINE) 2023; 23:11. [PMID: 37014302 PMCID: PMC10072106 DOI: 10.1093/jisesa/iead018] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/03/2023] [Accepted: 03/10/2023] [Indexed: 06/19/2023]
Abstract
The insect equivalent of taste buds are gustatory sensilla, which have been found on mouthparts, pharynxes, antennae, legs, wings, and ovipositors. Most gustatory sensilla are uniporous, but not all apparently uniporous sensilla are gustatory. Among sensilla containing more than one neuron, a tubular body on one dendrite is also indicative of a taste sensillum, with the tubular body adding tactile function. But not all taste sensilla are also tactile. Additional morphological criteria are often used to recognize if a sensillum is gustatory. Further confirmation of such criteria by electrophysiological or behavioral evidence is needed. The five canonical taste qualities to which insects respond are sweet, bitter, sour, salty, and umami. But not all tastants that insects respond to easily fit in these taste qualities. Categories of insect tastants can be based not only on human taste perception, but also on whether the response is deterrent or appetitive and on chemical structure. Other compounds that at least some insects taste include, but are not limited to: water, fatty acids, metals, carbonation, RNA, ATP, pungent tastes as in horseradish, bacterial lipopolysaccharides, and contact pheromones. We propose that, for insects, taste be defined not only as a response to nonvolatiles but also be restricted to responses that are, or are thought to be, mediated by a sensillum. This restriction is useful because some of the receptor proteins in gustatory sensilla are also found elsewhere.
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Affiliation(s)
- B H King
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA
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4
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Subbulakshmi Radhakrishnan S, Chakrabarti S, Sen D, Das M, Schranghamer TF, Sebastian A, Das S. A Sparse and Spike-Timing-Based Adaptive Photoencoder for Augmenting Machine Vision for Spiking Neural Networks. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2202535. [PMID: 35674268 DOI: 10.1002/adma.202202535] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/31/2022] [Indexed: 06/15/2023]
Abstract
The representation of external stimuli in the form of action potentials or spikes constitutes the basis of energy efficient neural computation that emerging spiking neural networks (SNNs) aspire to imitate. With recent evidence suggesting that information in the brain is more often represented by explicit firing times of the neurons rather than mean firing rates, it is imperative to develop novel hardware that can accelerate sparse and spike-timing-based encoding. Here a medium-scale integrated circuit composed of two cascaded three-stage inverters and one XOR logic gate fabricated using a total of 21 memtransistors based on photosensitive 2D monolayer MoS2 for spike-timing-based encoding of visual information, is introduced. It is shown that different illumination intensities can be encoded into sparse spiking with time-to-first-spike representing the illumination information, that is, higher intensities invoke earlier spikes and vice versa. In addition, non-volatile and analog programmability in the photoencoder is exploited for adaptive photoencoding that allows expedited spiking under scotopic (low-light) and deferred spiking under photopic (bright-light) conditions, respectively. Finally, low energy expenditure of less than 1 µJ by the 2D-memtransistor-based photoencoder highlights the benefits of in-sensor and bioinspired design that can be transformative for the acceleration of SNNs.
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Affiliation(s)
| | - Shakya Chakrabarti
- Electrical Engineering and Computer Science, Penn State University, University Park, PA, 16802, USA
| | - Dipanjan Sen
- Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
| | - Mayukh Das
- Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
| | - Thomas F Schranghamer
- Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
| | - Amritanand Sebastian
- Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
| | - Saptarshi Das
- Engineering Science and Mechanics, Penn State University, University Park, PA, 16802, USA
- Electrical Engineering and Computer Science, Penn State University, University Park, PA, 16802, USA
- Materials Science and Engineering, Penn State University, University Park, PA, 16802, USA
- Materials Research Institute, Penn State University, University Park, PA, 16802, USA
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5
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Snell NJ, Fisher JD, Hartmann GG, Zolyomi B, Talay M, Barnea G. Complex representation of taste quality by second-order gustatory neurons in Drosophila. Curr Biol 2022; 32:3758-3772.e4. [PMID: 35973432 PMCID: PMC9474709 DOI: 10.1016/j.cub.2022.07.048] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 04/08/2022] [Accepted: 07/19/2022] [Indexed: 01/24/2023]
Abstract
Sweet and bitter compounds excite different sensory cells and drive opposing behaviors. However, it remains unclear how sweet and bitter tastes are represented by the neural circuits linking sensation to behavior. To investigate this question in Drosophila, we devised trans-Tango(activity), a strategy for calcium imaging of second-order gustatory projection neurons based on trans-Tango, a genetic transsynaptic tracing technique. We found spatial overlap between the projection neuron populations activated by sweet and bitter tastants. The spatial representation of bitter tastants in the projection neurons was consistent, while that of sweet tastants was heterogeneous. Furthermore, we discovered that bitter tastants evoke responses in the gustatory receptor neurons and projection neurons upon both stimulus onset and offset and that bitter offset and sweet onset excite overlapping second-order projections. These findings demonstrate an unexpected complexity in the representation of sweet and bitter tastants by second-order neurons of the gustatory circuit.
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Affiliation(s)
- Nathaniel J Snell
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - John D Fisher
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Griffin G Hartmann
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Bence Zolyomi
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Mustafa Talay
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Gilad Barnea
- Department of Neuroscience, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA; The Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA.
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6
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Tom MT, Cortés Llorca L, Bucks S, Bisch-Knaden S, Hansson BS. Sex- and tissue-specific expression of chemosensory receptor genes in a hawkmoth. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.976521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
For the nocturnal hawkmoth Manduca sexta, olfactory and gustatory cues are essential for finding partners, food, and oviposition sites. Three chemosensory receptor families, odorant receptors (ORs), ionotropic receptors (IRs), and gustatory receptors (GRs) are involved in the detection of these stimuli. While many chemosensory receptor genes have been identified, knowledge of their expression profile in potentially chemoreceptive organs is incomplete. Here, we studied the expression patterns of chemosensory receptors in different tissues including the antennae, labial palps, proboscis, legs, wings and ovipositor. We compared the receptors’ expression in female and male moths both before and after mating by using the NanoString platform. This tool allowed us to measure expression levels of chemosensory receptor genes in a single reaction using probes designed against 71 OR, 29 IR and 49 GR transcripts. In all tissues investigated, we detected expression of genes from all three receptor families. The highest number of receptors was detected in the antennae (92), followed by the ovipositor (59), while the least number was detected in the hindlegs (21). The highest number of OR genes were expressed in the antennae (63), of which 24 were specific to this main olfactory organ. The highest number of IRs were also expressed in the antennae (16), followed by the ovipositor (15). Likewise, antennae and ovipositor expressed the highest number of GRs (13 and 14). Expression of the OR co-receptor MsexORCo, presumably a prerequisite for OR function, was found in the antennae, labial palps, forelegs and ovipositor. IR co-receptors MsexIR25a and MsexIR76b were expressed across all tested tissues, while expression of the IR co-receptor MsexIR8a was restricted to antennae and ovipositor. Comparing the levels of all 149 transcripts across the nine tested tissues allowed us to identify sex-biased gene expression in the antennae and the legs, two appendages that are also morphologically different between the sexes. However, none of the chemosensory receptors was differentially expressed based on the moths’ mating state. The observed gene expression patterns form a strong base for the functional characterization of chemosensory receptors and the understanding of olfaction and gustation at the molecular level in M. sexta.
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7
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Parkinson RH, Kessler SC, Scott J, Simpson A, Bu J, Al-Esawy M, Mahdi A, Miriyala A, Wright GA. Temporal responses of bumblebee gustatory neurons to sugars. iScience 2022; 25:104499. [PMID: 35733788 PMCID: PMC9207677 DOI: 10.1016/j.isci.2022.104499] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 05/19/2022] [Accepted: 05/26/2022] [Indexed: 11/05/2022] Open
Abstract
The sense of taste permits the recognition of valuable nutrients and the avoidance of potential toxins. Previously, we found that bumblebees have a specialized mechanism for sensing sugars whereby two gustatory receptor neurons (GRNs) within the galeal sensilla of the bees’ mouthparts exhibit bursts of spikes. Here, we show that the temporal firing patterns of these GRNs separate sugars into four distinct groups that correlate with sugar nutritional value and palatability. We also identified a third GRN that responded to stimulation with relatively high concentrations of fructose, sucrose, and maltose. Sugars that were nonmetabolizable or toxic suppressed the responses of bursting GRNs to sucrose. These abilities to encode information about sugar value are a refinement to the bumblebee’s sense of sweet taste that could be an adaptation that enables precise calculations of the nature and nutritional value of floral nectar. Up to three gustatory receptor neurons (GRNs) per galeal sensillum respond to sugars Bumblebee GRNs produce a bursting pattern in response to sugars of high nutritional value Response patterns of GRNs can be grouped by sugar nutritional value Nonmetabolizable and toxic sugars suppress the responses of bursting GRNs to sucrose
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Affiliation(s)
| | - Sébastien C Kessler
- Institute of Neuroscience, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK
| | - Jennifer Scott
- Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK
| | - Alexander Simpson
- Institute of Neuroscience, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK
| | - Jennifer Bu
- School of Medicine, University of California, San Diego, San Diego, CA 92093, USA
| | | | - Adam Mahdi
- Oxford Internet Institute, University of Oxford, Oxford OX1 3JS, UK
| | - Ashwin Miriyala
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford OX1 3SR, UK
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8
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Pontes G, Latorre-Estivalis JM, Gutiérrez ML, Cano A, Berón de Astrada M, Lorenzo MG, Barrozo RB. Molecular and functional basis of high-salt avoidance in a blood-sucking insect. iScience 2022; 25:104502. [PMID: 35720264 PMCID: PMC9204723 DOI: 10.1016/j.isci.2022.104502] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/14/2022] [Accepted: 05/26/2022] [Indexed: 12/05/2022] Open
Abstract
Salts are essential nutrients required for many physiological processes, and accordingly, their composition and concentration are tightly regulated. Taste is the ultimate sensory modality involved in resource quality assessment, resulting in acceptance or rejection. Here we found that high salt concentrations elicit feeding avoidance in the blood-sucking bug Rhodnius prolixus and elucidate the molecular and neurophysiological mechanisms involved. We found that high-salt avoidance is mediated by a salt-sensitive antennal gustatory receptor neuron (GRN). Using RNAi, we demonstrate that this process requires two amiloride-sensitive pickpocket channels (PPKs; Rpro PPK014276 and Rpro PPK28) expressed within these cells. We found that antennal GRNs project to the insect primary olfactory center, the antennal lobes, revealing these centers as potential sites for the integration of taste and olfactory host-derived cues. Moreover, the identification of the gustatory basis of high-salt detection in a hematophagous insect suggests novel targets for the prevention of biting and feeding.
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Affiliation(s)
- Gina Pontes
- Grupo de Neuroetología de Insectos Vectores, Laboratorio Fisiología de Insectos, Instituto de Biodiversidad, Biología Experimental y Aplicada, CONICET - UBA, Departamento Biodiversidad y Biología Experimental, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - José Manuel Latorre-Estivalis
- Grupo de Comportamento de Vetores e Interação com Patógenos-CNPq, Centro de Pesquisas René Rachou/FIOCRUZ, Belo Horizonte, Brazil
| | - María Laura Gutiérrez
- Grupo de Neuroetología de Insectos Vectores, Laboratorio Fisiología de Insectos, Instituto de Biodiversidad, Biología Experimental y Aplicada, CONICET - UBA, Departamento Biodiversidad y Biología Experimental, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Agustina Cano
- Grupo de Neuroetología de Insectos Vectores, Laboratorio Fisiología de Insectos, Instituto de Biodiversidad, Biología Experimental y Aplicada, CONICET - UBA, Departamento Biodiversidad y Biología Experimental, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Martin Berón de Astrada
- Laboratorio de Fisiología de la Visión, Instituto de Biociencias, Biotecnología y Biología Traslacional, Departamento de Fisiología, Biología Molecular y Celular, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Marcelo G. Lorenzo
- Grupo de Comportamento de Vetores e Interação com Patógenos-CNPq, Centro de Pesquisas René Rachou/FIOCRUZ, Belo Horizonte, Brazil
| | - Romina B. Barrozo
- Grupo de Neuroetología de Insectos Vectores, Laboratorio Fisiología de Insectos, Instituto de Biodiversidad, Biología Experimental y Aplicada, CONICET - UBA, Departamento Biodiversidad y Biología Experimental, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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9
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Sun LL, Liu XL, Wang YN, Berg BG, Xie GY, Chen WB, Liu Y, Wang GR, Zhao XC, Tang QB. Neuronal architecture and functional mapping of the taste center of larval Helicoverpa armigera (Lepidoptera: Noctuidae). INSECT SCIENCE 2022; 29:730-748. [PMID: 34427391 DOI: 10.1111/1744-7917.12965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
The sense of taste plays a crucial role in herbivorous insects by discriminating nutrients from complex plant metabolic compounds. The peripheral coding of taste has been thoroughly studied in many insect species, but the central gustatory pathways are poorly described. In the present study, we characterized single neurons in the gnathal ganglion of Helicoverpa armigera larvae using the intracellular recording/staining technique. We identified different types of neurons, including sensory neurons, interneurons, and motor neurons. The morphologies of these neurons were largely diverse and their arborizations seemingly covered the whole gnathal ganglion. The representation of the single neurons responding to the relevant stimuli of sweet and bitter cues showed no distinct patterns in the gnathal ganglion. We postulate that taste signals may be processed in a manner consistent with the principle of population coding in the gnathal ganglion of H. armigera larvae.
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Affiliation(s)
- Long-Long Sun
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Xiao-Lan Liu
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Ya-Nan Wang
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Bente G Berg
- Chemosensory laboratory, Department of Psychology, Norwegian University of Science and Technology, Trondheim, 7489, Norway
| | - Gui-Ying Xie
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Wen-Bo Chen
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yang Liu
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Gui-Rong Wang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xin-Cheng Zhao
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Qing-Bo Tang
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
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10
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Maier GL, Komarov N, Meyenhofer F, Kwon JY, Sprecher SG. Taste sensing and sugar detection mechanisms in Drosophila larval primary taste center. eLife 2021; 10:67844. [PMID: 34859782 PMCID: PMC8709573 DOI: 10.7554/elife.67844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 11/23/2021] [Indexed: 11/25/2022] Open
Abstract
Despite the small number of gustatory sense neurons, Drosophila larvae are able to sense a wide range of chemicals. Although evidence for taste multimodality has been provided in single neurons, an overview of gustatory responses at the periphery is missing and hereby we explore whole-organ calcium imaging of the external taste center. We find that neurons can be activated by different combinations of taste modalities, including opposite hedonic valence and identify distinct temporal dynamics of response. Although sweet sensing has not been fully characterized so far in the external larval gustatory organ, we recorded responses elicited by sugar. Previous findings established that larval sugar sensing relies on the Gr43a pharyngeal receptor, but the question remains if external neurons contribute to this taste. Here, we postulate that external and internal gustation use distinct and complementary mechanisms in sugar sensing and we identify external sucrose sensing neurons.
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Affiliation(s)
- G Larisa Maier
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Nikita Komarov
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Felix Meyenhofer
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jae Young Kwon
- Department of Biological Sciences, Sungkyunkwan University, Suwon, Republic of Korea
| | - Simon G Sprecher
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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11
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McCaughey SA. Variation in the gene Tas1r3 reveals complex temporal properties of mouse brainstem taste responses to sweeteners. Am J Physiol Regul Integr Comp Physiol 2021; 321:R751-R767. [PMID: 34523351 PMCID: PMC8616626 DOI: 10.1152/ajpregu.00001.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 11/22/2022]
Abstract
The gene Tas1r3 codes for the protein T1R3, which dimerizes with T1R2 to form a sweetener-binding receptor in taste cells. Tas1r3 influences sweetener preferences in mice, as shown by work with a 129.B6-Tas1r3 segregating congenic strain on a 129P3/J (129) genetic background; members of this strain vary in whether they do or do not have one copy of a donor fragment with the C57BL/6ByJ (B6) allele for Tas1r3 (B6/129 and 129/129 mice, respectively). Taste-evoked neural responses were measured in the nucleus of the solitary tract (NST), the first central gustatory relay, in B6/129 and 129/129 littermates, to examine how the activity dependent on the T1R2/T1R3 receptor is distributed across neurons and over time. Responses to sucrose were larger in B6/129 than in 129/129 mice, but only during a later, tonic response portion (>600 ms) sent to different cells than the earlier, phasic response. Similar results were found for artificial sweeteners, whose responses were best considered as complex spatiotemporal patterns. There were also group differences in burst firing of NST cells, with a significant positive correlation between bursting prevalence and sucrose response size in only the 129/129 group. The results indicate that sweetener transduction initially occurs through T1R3-independent mechanisms, after which the T1R2/T1R3 receptor initiates a separate, spatially distinct response, with the later period dominating sweet taste perceptions and driving sugar preferences. Furthermore, the current data suggest that burst firing is distributed across NST neurons nonrandomly and in a manner that may amplify weak incoming gustatory signals.
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Affiliation(s)
- Stuart A McCaughey
- Center for Medical Education, Ball State University, Muncie, Indiana
- Monell Chemical Senses Center, Philadelphia, Pennsylvania
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12
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Yang J, Guo H, Jiang NJ, Tang R, Li GC, Huang LQ, van Loon JJA, Wang CZ. Identification of a gustatory receptor tuned to sinigrin in the cabbage butterfly Pieris rapae. PLoS Genet 2021; 17:e1009527. [PMID: 34264948 PMCID: PMC8282186 DOI: 10.1371/journal.pgen.1009527] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/01/2021] [Indexed: 11/18/2022] Open
Abstract
Glucosinolates are token stimuli in host selection of many crucifer specialist
insects, but the underlying molecular basis for host selection in these insects
remains enigmatic. Using a combination of behavioral, electrophysiological, and
molecular methods, we investigate glucosinolate receptors in the cabbage
butterfly Pieris rapae. Sinigrin, as a potent feeding
stimulant, elicited activity in larval maxillary lateral sensilla styloconica,
as well as in adult medial tarsal sensilla. Two P.
rapae gustatory receptor genes PrapGr28
and PrapGr15 were identified with high expression in female
tarsi, and the subsequent functional analyses showed that
Xenopus oocytes only expressing PrapGr28
had specific responses to sinigrin; when ectopically expressed in
Drosophila sugar sensing neurons, PrapGr28 conferred
sinigrin sensitivity to these neurons. RNA interference experiments further
showed that knockdown of PrapGr28 reduced the sensitivity of
adult medial tarsal sensilla to sinigrin. Taken together, we conclude that
PrapGr28 is a gustatory receptor tuned to sinigrin in P.
rapae, which paves the way for revealing the molecular
basis of the relationships between crucifer plants and their specialist
insects. Preference of crucifer specialist insects to glucosinolates is well known in the
field of insect-plant interactions, but its molecular basis is unclear. This
study uses an integrative approach to investigate the molecular basis of
glucosinolate detection by gustatory receptor neurons in the larval mouthparts
and adult forelegs of the cabbage butterfly Pieris rapae, and
finally reveal that PrapGr28 is a bitter receptor tuned to sinigrin. The current
work takes a significant step towards identifying gustatory receptors tuned to
glucosinolates, crucial recognition signals in crucifer host plants, providing
insights into co-evolution of herbivorous insects and their host plants.
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Affiliation(s)
- Jun Yang
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
- CAS Center for Excellence in Biotic Interactions, University of Chinese
Academy of Sciences, Beijing, China
| | - Hao Guo
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
- CAS Center for Excellence in Biotic Interactions, University of Chinese
Academy of Sciences, Beijing, China
| | - Nan-Ji Jiang
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
| | - Rui Tang
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
| | - Guo-Cheng Li
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
- CAS Center for Excellence in Biotic Interactions, University of Chinese
Academy of Sciences, Beijing, China
| | - Ling-Qiao Huang
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
| | - Joop J. A. van Loon
- Laboratory of Entomology, Plant Sciences Group, Wageningen University and
Research, Wageningen, the Netherlands
| | - Chen-Zhu Wang
- State Key Laboratory of Integrated Management of Pest Insects and
Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing,
China
- CAS Center for Excellence in Biotic Interactions, University of Chinese
Academy of Sciences, Beijing, China
- * E-mail:
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13
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Subbulakshmi Radhakrishnan S, Sebastian A, Oberoi A, Das S, Das S. A biomimetic neural encoder for spiking neural network. Nat Commun 2021; 12:2143. [PMID: 33837210 PMCID: PMC8035177 DOI: 10.1038/s41467-021-22332-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 03/09/2021] [Indexed: 02/07/2023] Open
Abstract
Spiking neural networks (SNNs) promise to bridge the gap between artificial neural networks (ANNs) and biological neural networks (BNNs) by exploiting biologically plausible neurons that offer faster inference, lower energy expenditure, and event-driven information processing capabilities. However, implementation of SNNs in future neuromorphic hardware requires hardware encoders analogous to the sensory neurons, which convert external/internal stimulus into spike trains based on specific neural algorithm along with inherent stochasticity. Unfortunately, conventional solid-state transducers are inadequate for this purpose necessitating the development of neural encoders to serve the growing need of neuromorphic computing. Here, we demonstrate a biomimetic device based on a dual gated MoS2 field effect transistor (FET) capable of encoding analog signals into stochastic spike trains following various neural encoding algorithms such as rate-based encoding, spike timing-based encoding, and spike count-based encoding. Two important aspects of neural encoding, namely, dynamic range and encoding precision are also captured in our demonstration. Furthermore, the encoding energy was found to be as frugal as ≈1-5 pJ/spike. Finally, we show fast (≈200 timesteps) encoding of the MNIST data set using our biomimetic device followed by more than 91% accurate inference using a trained SNN.
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Affiliation(s)
| | - Amritanand Sebastian
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA
| | - Aaryan Oberoi
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA
| | - Sarbashis Das
- Department of Electrical Engineering, Pennsylvania State University, University Park, PA, USA
| | - Saptarshi Das
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA.
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA.
- Materials Research Institute, Pennsylvania State University, University Park, PA, USA.
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14
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Stöckl AL, Kelber A. Fuelling on the wing: sensory ecology of hawkmoth foraging. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:399-413. [PMID: 30880349 PMCID: PMC6579779 DOI: 10.1007/s00359-019-01328-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 02/25/2019] [Accepted: 03/05/2019] [Indexed: 11/28/2022]
Abstract
Hawkmoths (Lepidoptera, Sphingidae) comprise around 1500 species, most of which forage on nectar from flowers in their adult stage, usually while hovering in front of the flower. The majority of species have a nocturnal lifestyle and are important nocturnal pollinators, but some species have turned to a diurnal lifestyle. Hawkmoths use visual and olfactory cues including CO2 and humidity to detect and recognise rewarding flowers; they find the nectary in the flowers by means of mechanoreceptors on the proboscis and vision, evaluate it with gustatory receptors on the proboscis, and control their hovering flight position using antennal mechanoreception and vision. Here, we review what is presently known about the sensory organs and sensory-guided behaviour that control feeding behaviour of this fascinating pollinator taxon. We also suggest that more experiments on hawkmoth behaviour in natural settings are needed to fully appreciate their sensory capabilities.
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Affiliation(s)
- Anna Lisa Stöckl
- Biozentrum, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Almut Kelber
- Department of Biology, Lund University, Sölvegatan 35, 22362, Lund, Sweden.
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15
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Sang J, Rimal S, Lee Y. Gustatory receptor 28b is necessary for avoiding saponin in Drosophila melanogaster. EMBO Rep 2019; 20:embr.201847328. [PMID: 30622216 DOI: 10.15252/embr.201847328] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/10/2018] [Accepted: 12/14/2018] [Indexed: 11/09/2022] Open
Abstract
Saponins function as a natural self-defense mechanism for plants to deter various insects due to their unpleasant taste and their toxicity. Here, we provide evidence that saponin from Quillaja saponaria functions as an antifeedant as well as an insecticide to ward off insects in both the larval and the adult stages. Using a behavioral screen of 26 mutant fly lines, we show that the Gr28b gene cluster plays a role in saponin avoidance in the labellum. The Gr28b mutant does not avoid saponin and exhibits increased lethality when fed saponin-mixed food. Tissue-specific rescue experiments with five different Gr28b isoforms revealed that only the Gr28b.c isoform is required for saponin sensation. We propose that in contrast to sensing many other bitter compounds, saponin sensing does not require the function of core taste receptors, such as GR32a, GR33a, and GR66a. Our results reveal a novel role for GR28b in taste. In addition, the ability of saponin to act as insecticides as well as antifeedants suggests its potential application in controlling insect pests.
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Affiliation(s)
- Jiun Sang
- Department of Bio and Fermentation Convergence Technology, Kookmin University BK21 PLUS project, Seoul, Korea
| | - Suman Rimal
- Department of Bio and Fermentation Convergence Technology, Kookmin University BK21 PLUS project, Seoul, Korea
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University BK21 PLUS project, Seoul, Korea
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16
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Abstract
Sensory neurons for smell and taste in insects reside in sensilla. Experiments in bumblebees reveal an unusual benefit of this arrangement: interaction between co-housed gustatory neurons promotes bursting in their responses and delays their adaptation.
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Affiliation(s)
- Aarush Mohit Mittal
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India
| | - Swikriti Saran Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India
| | - Nitin Gupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India.
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17
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Miyaoka S, Iwamori H, Miyaoka Y. Distribution of Recognition Times to Fruity Flavor of Gummy Candies in Healthy Adults. Perception 2018; 47:851-859. [PMID: 29771190 DOI: 10.1177/0301006618777940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Times for recognition of fruity flavors in six gummy candies were measured using an electromyography-based system in 23 young healthy participants. They were instructed to chew one of the gummy candies at a random order and to press a button as soon as possible when they recognized what flavor was. The measured 181 recognition times showed two distributions, normally ( n = 107) and non-normally ( n = 74). The overall average of the normal distribution was 7.5 seconds (±2.34 seconds; standard deviation), and there were no differences in the average ratios among the gummy candies. Eighteen of the participants reported 41 inconsistent reports with flavors that were provided by the manufacturer. The most frequently observed report was an apple-flavored gummy candy (14, 34.1%) mainly for a pear-flavored. However, there was no significant correlation between the numbers of recognition times and those of inconsistent flavors among the used gummy candies.
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Affiliation(s)
- Satomi Miyaoka
- Department of Mental Health Science, Graduate School of Rehabilitation, Niigata University of Rehabilitation, Murakami, Japan
| | - Hajime Iwamori
- Department of Health and Nutrition, Niigata University of Health and Welfare, Niigata, Japan
| | - Yozo Miyaoka
- Department of Health and Nutrition, Niigata University of Health and Welfare, Niigata, Japan
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18
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Miriyala A, Kessler S, Rind FC, Wright GA. Burst Firing in Bee Gustatory Neurons Prevents Adaptation. Curr Biol 2018; 28:1585-1594.e3. [PMID: 29754900 DOI: 10.1016/j.cub.2018.03.070] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 02/20/2018] [Accepted: 03/29/2018] [Indexed: 10/16/2022]
Abstract
Animals detect changes in the environment using modality-specific, peripheral sensory neurons. The insect gustatory system encodes tastant identity and concentration through the independent firing of gustatory receptor neurons (GRNs) that spike rapidly at stimulus onset and quickly adapt. Here, we show the first evidence that concentrated sugar evokes a temporally structured burst pattern of spiking involving two GRNs within the gustatory sensilla of bumblebees. Bursts of spikes resulted when a sucrose-activated GRN was inhibited by another GRN at a frequency of ∼22 Hz during the first 1 s of stimulation. Pharmacological blockade of gap junctions abolished bursting, indicating that bee GRNs have electrical synapses that produce a temporal pattern of spikes when one GRN is activated by a sugar ligand. Bursting permitted bee GRNs to maintain a high rate of spiking and to exhibit the slowest rate of adaptation of any insect species. Feeding bout duration correlated with coherent bursting; only sugar concentrations that produced bursting evoked the bumblebee's feeding reflex. Volume of solution imbibed was a direct function of time in contact with food. We propose that gap junctions among GRNs enable a sustained rate of GRN spiking that is necessary to drive continuous feeding by the bee proboscis.
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Affiliation(s)
- Ashwin Miriyala
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Sébastien Kessler
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - F Claire Rind
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Geraldine A Wright
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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19
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Simcock NK, Gray H, Bouchebti S, Wright GA. Appetitive olfactory learning and memory in the honeybee depend on sugar reward identity. JOURNAL OF INSECT PHYSIOLOGY 2018; 106:71-77. [PMID: 28844654 DOI: 10.1016/j.jinsphys.2017.08.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 08/21/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
One of the most important tasks of the brain is to learn and remember information associated with food. Studies in mice and Drosophila have shown that sugar rewards must be metabolisable to form lasting memories, but few other animals have been studied. Here, we trained adult, worker honeybees (Apis mellifera) in two olfactory tasks (massed and spaced conditioning) known to affect memory formation to test how the schedule of reinforcement and the nature of a sugar reward affected learning and memory. The antennae and mouthparts of honeybees were most sensitive to sucrose but glucose and fructose were equally phagostimulatory. Whether or not bees could learn the tasks depended on sugar identity and concentration. However, only bees rewarded with glucose or sucrose formed robust long-term memory. This was true for bees trained in both the massed and spaced conditioning tasks. Honeybees fed with glucose or fructose exhibited a surge in haemolymph sugar of greater than 120mM within 30s that remained elevated for as long as 20min after a single feeding event. For bees fed with sucrose, this change in haemolymph glucose and fructose occurred with a 30s delay. Our data showed that olfactory learning in honeybees was affected by sugar identity and concentration, but that olfactory memory was most strongly affected by sugar identity. Taken together, these data suggest that the neural mechanisms involved in memory formation sense rapid changes in haemolymph glucose that occur during and after conditioning.
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Affiliation(s)
- Nicola K Simcock
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Helen Gray
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Sofia Bouchebti
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Geraldine A Wright
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom.
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20
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Haverkamp A, Hansson BS, Baldwin IT, Knaden M, Yon F. Floral Trait Variations Among Wild Tobacco Populations Influence the Foraging Behavior of Hawkmoth Pollinators. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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21
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Abstract
The ability to identify nutrient-rich food and avoid toxic substances is essential for an animal's survival. Although olfaction and vision contribute to food detection, the gustatory system acts as a final checkpoint control for food acceptance or rejection. The vinegar fly Drosophila melanogaster tastes many of the same stimuli as mammals and provides an excellent model system for comparative studies of taste detection. The relative simplicity of the fly brain and behaviors, along with the molecular genetic and functional approaches available in this system, allow the examination of gustatory neural circuits from sensory input to motor output. This review discusses the molecules and cells that detect taste compounds in the periphery and the circuits that process taste information in the brain. These studies are providing insight into how the detection of taste compounds regulates feeding decisions.
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Affiliation(s)
- Kristin Scott
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720;
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22
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Abstract
Taste allows animals to discriminate the value and potential toxicity of food prior to ingestion. Many tastants elicit an innate attractive or avoidance response that is modifiable with nutritional state and prior experience. A powerful genetic tool kit, well-characterized gustatory system, and standardized behavioral assays make the fruit fly, Drosophila melanogaster, an excellent system for investigating taste processing and memory. Recent studies have used this system to identify the neural basis for acquired taste preference. These studies have revealed a role for dopamine-mediated plasticity of the mushroom bodies that modulate the threshold of response to appetitive tastants. The identification of neural circuitry regulating taste memory provides a system to study the genetic and physiological processes that govern plasticity within a defined memory circuit.
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Affiliation(s)
- Pavel Masek
- a Department of Biology , Binghamton University , Binghamton , NY , USA
| | - Alex C Keene
- b Department of Biological Sciences , Florida Atlantic University , Jupiter , FL , USA
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23
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Tauber JM, Brown EB, Li Y, Yurgel ME, Masek P, Keene AC. A subset of sweet-sensing neurons identified by IR56d are necessary and sufficient for fatty acid taste. PLoS Genet 2017; 13:e1007059. [PMID: 29121639 PMCID: PMC5697886 DOI: 10.1371/journal.pgen.1007059] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 11/21/2017] [Accepted: 10/08/2017] [Indexed: 01/10/2023] Open
Abstract
Fat represents a calorically potent food source that yields approximately twice the amount of energy as carbohydrates or proteins per unit of mass. The highly palatable taste of free fatty acids (FAs), one of the building blocks of fat, promotes food consumption, activates reward circuitry, and is thought to contribute to hedonic feeding underlying many metabolism-related disorders. Despite a role in the etiology of metabolic diseases, little is known about how dietary fats are detected by the gustatory system to promote feeding. Previously, we showed that a broad population of sugar-sensing taste neurons expressing Gustatory Receptor 64f (Gr64f) is required for reflexive feeding responses to both FAs and sugars. Here, we report a genetic silencing screen to identify specific populations of taste neurons that mediate fatty acid (FA) taste. We find neurons identified by expression of Ionotropic Receptor 56d (IR56d) are necessary and sufficient for reflexive feeding response to FAs. Functional imaging reveals that IR56d-expressing neurons are responsive to short- and medium-chain FAs. Silencing IR56d neurons selectively abolishes FA taste, and their activation is sufficient to drive feeding responses. Analysis of co-expression with Gr64f identifies two subpopulations of IR56d-expressing neurons. While physiological imaging reveals that both populations are responsive to FAs, IR56d/Gr64f neurons are activated by medium-chain FAs and are sufficient for reflexive feeding response to FAs. Moreover, flies can discriminate between sugar and FAs in an aversive taste memory assay, indicating that FA taste is a unique modality in Drosophila. Taken together, these findings localize FA taste within the Drosophila gustatory center and provide an opportunity to investigate discrimination between different categories of appetitive tastants. Fat represents a calorically potent food source that yields approximately twice the amount of energy as carbohydrates or proteins per unit of mass. Dietary lipids are comprised of both triacylglycerides and FAs, and growing evidence suggests that it is the free FAs that are detected by the gustatory system. The highly palatable taste of FAs promotes food consumption, activates reward centers in mammals, and is thought to contribute to hedonic feeding that underlies many metabolism-related disorders. Despite a role in the etiology of metabolic diseases, little is known about how dietary fats are detected by the gustatory system to promote feeding. We have identified a subset of sugar-sensing neurons in the fly that also responds to medium-chain FAs and are necessary and sufficient for behavioral response to FAs. Further, we find that despite being sensed by shared neuronal populations, flies can differentiate between the taste of sugar and FAs, fortifying the notion that FAs and sugar represent distinct taste modalities in flies.
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Affiliation(s)
- John M. Tauber
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
| | - Elizabeth B. Brown
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
| | - Yuanyuan Li
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States of America
| | - Maria E. Yurgel
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
| | - Pavel Masek
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States of America
| | - Alex C. Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, United States of America
- * E-mail:
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24
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Odor-evoked inhibition of olfactory sensory neurons drives olfactory perception in Drosophila. Nat Commun 2017; 8:1357. [PMID: 29116083 PMCID: PMC5676773 DOI: 10.1038/s41467-017-01185-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/24/2017] [Indexed: 11/28/2022] Open
Abstract
Inhibitory response occurs throughout the nervous system, including the peripheral olfactory system. While odor-evoked excitation in peripheral olfactory cells is known to encode odor information, the molecular mechanism and functional roles of odor-evoked inhibition remain largely unknown. Here, we examined Drosophila olfactory sensory neurons and found that inhibitory odors triggered outward receptor currents by reducing the constitutive activities of odorant receptors, inhibiting the basal spike firing in olfactory sensory neurons. Remarkably, this odor-evoked inhibition of olfactory sensory neurons elicited by itself a full range of olfactory behaviors from attraction to avoidance, as did odor-evoked olfactory sensory neuron excitation. These results indicated that peripheral inhibition is comparable to excitation in encoding sensory signals rather than merely regulating excitation. Furthermore, we demonstrated that a bidirectional code with both odor-evoked inhibition and excitation in single olfactory sensory neurons increases the odor-coding capacity, providing a means of efficient sensory encoding. It is well established that odor-evoked excitation in olfactory sensory neurons (OSNs) encodes odor information. Here the authors report that odor-evoked inhibition in OSNs of Drosophila also encodes odor identity, and can in itself drive both attraction and avoidance behaviors.
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25
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Boronat-García A, Reiter S, Sun K, Stopfer M. New Methods to Study Gustatory Coding. J Vis Exp 2017. [PMID: 28715373 PMCID: PMC5608530 DOI: 10.3791/55868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The sense of taste allows animals to detect chemicals in the environment, giving rise to behaviors critical for survival. When Gustatory Receptor Neurons (GRNs) detect tastant molecules, they encode information about the identity and concentration of the tastant as patterns of electrical activity that then propagate to follower neurons in the brain. These patterns constitute internal representations of the tastant, which then allow the animal to select actions and form memories. The use of relatively simple animal models has been a powerful tool to study basic principles in sensory coding. Here, we propose three new methods to study gustatory coding using the moth Manduca sexta. First, we present a dissection procedure for exposing the maxillary nerves and the subesophageal zone (SEZ), allowing recording of the activity of GRNs from their axons. Second, we describe the use of extracellular electrodes to record the activity of multiple GRNs by placing tetrode wires directly into the maxillary nerve. Third, we present a new system for delivering and monitoring, with high temporal precision, pulses of different tastants. These methods allow the characterization of neuronal responses in vivo directly from GRNs before, during and after tastants are delivered. We provide examples of voltage traces recorded from multiple GRNs, and present an example of how a spike sorting technique can be applied to the data to identify the responses of individual neurons. Finally, to validate our recording approach, we compare extracellular recordings obtained from GRNs with tetrodes to intracellular recordings obtained with sharp glass electrodes.
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Affiliation(s)
- Alejandra Boronat-García
- National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)
| | - Sam Reiter
- National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH); Max Planck Institute for Brain Research
| | - Kui Sun
- National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)
| | - Mark Stopfer
- National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH);
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26
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Feng B, Guo Q, Zheng K, Qin Y, Du Y. Antennal transcriptome analysis of the piercing moth Oraesia emarginata (Lepidoptera: Noctuidae). PLoS One 2017; 12:e0179433. [PMID: 28614384 PMCID: PMC5470721 DOI: 10.1371/journal.pone.0179433] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 05/29/2017] [Indexed: 11/25/2022] Open
Abstract
The piercing fruit moth Oraesia emarginata is an economically significant pest; however, our understanding of its olfactory mechanisms in infestation is limited. The present study conducted antennal transcriptome analysis of olfactory genes using real-time quantitative reverse transcription PCR analysis (RT-qPCR). We identified a total of 104 candidate chemosensory genes from several gene families, including 35 olfactory receptors (ORs), 41 odorant-binding proteins, 20 chemosensory proteins, 6 ionotropic receptors, and 2 sensory neuron membrane proteins. Seven candidate pheromone receptors (PRs) and 3 candidate pheromone-binding proteins (PBPs) for sex pheromone recognition were found. OemaOR29 and OemaPBP1 had the highest fragments per kb per million fragments (FPKM) values in all ORs and OBPs, respectively. Eighteen olfactory genes were upregulated in females, including 5 candidate PRs, and 20 olfactory genes were upregulated in males, including 2 candidate PRs (OemaOR29 and 4) and 2 PBPs (OemaPBP1 and 3). These genes may have roles in mediating sex-specific behaviors. Most candidate olfactory genes of sex pheromone recognition (except OemaOR29 and OemaPBP3) in O. emarginata were not clustered with those of studied noctuid species (type I pheromone). In addition, OemaOR29 was belonged to cluster PRIII, which comprise proteins that recognize type II pheromones instead of type I pheromones. The structure and function of olfactory genes that encode sex pheromones in O. emarginata might thus differ from those of other studied noctuids. The findings of the present study may help explain the molecular mechanism underlying olfaction and the evolution of olfactory genes encoding sex pheromones in O. emarginata.
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Affiliation(s)
- Bo Feng
- Institute of Health and Environmental Ecology, Wenzhou Medical University, University Town, Wenzhou, Zhejiang, China
| | - Qianshuang Guo
- Institute of Health and Environmental Ecology, Wenzhou Medical University, University Town, Wenzhou, Zhejiang, China
| | - Kaidi Zheng
- Institute of Health and Environmental Ecology, Wenzhou Medical University, University Town, Wenzhou, Zhejiang, China
| | - Yuanxia Qin
- Department of Research and Development, Newcon Inc., Ningbo, Zhejiang, China
| | - Yongjun Du
- Institute of Health and Environmental Ecology, Wenzhou Medical University, University Town, Wenzhou, Zhejiang, China
- * E-mail:
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27
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Pentzold S, Burse A, Boland W. Contact chemosensation of phytochemicals by insect herbivores. Nat Prod Rep 2017; 34:478-483. [PMID: 28485430 PMCID: PMC5436039 DOI: 10.1039/c7np00002b] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Contact chemosensation, or tasting, is a complex process governed by nonvolatile phytochemicals that tell host-seeking insects whether they should accept or reject a plant. During this process, insect gustatory receptors (GRs) contribute to deciphering a host plant's metabolic code. GRs recognise many different classes of nonvolatile compounds; some GRs are likely to be narrowly tuned and others, broadly tuned. Although primary and/or secondary plant metabolites influence the insect's feeding choice, their decoding by GRs is challenging, because metabolites in planta occur in complex mixtures that have additive or inhibitory effects; in diverse forms composed of structurally unrelated molecules; and at different concentrations depending on the plant species, its tissue and developmental stage. Future studies of the mechanism of insect herbivore GRs will benefit from functional characterisation taking into account the spatio-temporal dynamics and diversity of the plant's metabolome. Metabolic information, in turn, will help to elucidate the impact of single ligands and complex natural mixtures on the insect's feeding choice.
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Affiliation(s)
- Stefan Pentzold
- Max Planck Institute for Chemical Ecology, Department of Bioorganic Chemistry, Hans-Knöll-Str. 8, D-07745 Jena, Germany.
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28
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Asparch Y, Pontes G, Masagué S, Minoli S, Barrozo RB. Kissing bugs can generalize and discriminate between different bitter compounds. ACTA ACUST UNITED AC 2016; 110:99-106. [PMID: 27865772 DOI: 10.1016/j.jphysparis.2016.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 11/09/2016] [Accepted: 11/15/2016] [Indexed: 11/25/2022]
Abstract
Animals make use of contact chemoreception structures to examine the quality of potential food sources. During this evaluation they can detect nutritious compounds that promote feeding and recognize toxins that trigger evasive behaviors. Although animals can easily distinguish between stimuli of different gustatory qualities (bitter, salty, sweet, etc.), their ability to discriminate between compounds of the same quality may be limited. Numerous plants produce alkaloids, compounds that elicit aversive behaviors in phytophagous insects and almost uniformly evoke a bitter taste for man. In hematophagous insects, however, the effect of feeding deterrent molecules has been barely studied. Recent studies showed that feeding in Rhodnius prolixus can be negatively modulated by the presence of alkaloids such as quinine (QUI) and caffeine (CAF), compounds that elicit similar aversive responses. Here, we applied associative and non-associative learning paradigms to examine under two behavioral contexts the ability of R. prolixus to distinguish, discriminate and/or generalize between these two bitter compounds, QUI and CAF. Our results show that bugs innately repelled by bitter compounds can change their behavior from avoidance to indifference or even to preference according to their previous experiences. After an aversive operant conditioning with QUI or CAF, R. prolixus modified its behavior in a direct but also in a cross-compound manner, suggesting the occurrence of a generalization process between these two alkaloids. Conversely, after a long pre-exposure to each alkaloid, bugs decreased their avoidance to the compound used during pre-exposure but still expressed an avoidance of the novel compound, proving that QUI and CAF are detected separately. Our results suggest that R. prolixus is able to discriminate between QUI and CAF, although after an associative conditioning they express a symmetrical cross-generalization. This kind of studies adds insight into the gustatory sense of a blood-sucking model but also into the learning abilities of hematophagous insects.
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Affiliation(s)
- Yamila Asparch
- Laboratorio Fisiología de Insectos, IBBEA, CONICET-UBA, DBBE, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gina Pontes
- Laboratorio Fisiología de Insectos, IBBEA, CONICET-UBA, DBBE, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Santiago Masagué
- Laboratorio Fisiología de Insectos, IBBEA, CONICET-UBA, DBBE, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Sebastian Minoli
- Laboratorio Fisiología de Insectos, IBBEA, CONICET-UBA, DBBE, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Romina B Barrozo
- Laboratorio Fisiología de Insectos, IBBEA, CONICET-UBA, DBBE, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
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Stevenson PC, Nicolson SW, Wright GA. Plant secondary metabolites in nectar: impacts on pollinators and ecological functions. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12761] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Philip C. Stevenson
- Royal Botanic Gardens, Kew SurreyTW9 3AB UK
- Natural Resources Institute University of Greenwich KentME4 4TB UK
| | - Susan W. Nicolson
- Department of Zoology & Entomology University of Pretoria Private Bag X20 Hatfield0028 South Africa
| | - Geraldine A. Wright
- Centre for Behaviour and Evolution Institute of Neuroscience Newcastle University Newcastle upon TyneNE1 7RU UK
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To feed or not to feed: circuits involved in the control of feeding in insects. Curr Opin Neurobiol 2016; 41:87-91. [PMID: 27649465 DOI: 10.1016/j.conb.2016.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/12/2016] [Accepted: 09/05/2016] [Indexed: 11/23/2022]
Abstract
To feed or not to feed is a dilemma faced by every animal. The sense of taste is fundamental to the control of food intake. It permits recognition of nutrients, the rejection of toxins, and provides feedback for the coordination of feeding. The suboesophageal zone of the insect brain uses taste information to orchestrate the motor programs responsible for mouthparts coordination during feeding. Discovering the structure of the relevant neural circuits is a work in progress.
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31
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Haverkamp A, Yon F, Keesey IW, Mißbach C, Koenig C, Hansson BS, Baldwin IT, Knaden M, Kessler D. Hawkmoths evaluate scenting flowers with the tip of their proboscis. eLife 2016; 5:e15039. [PMID: 27146894 PMCID: PMC4884077 DOI: 10.7554/elife.15039] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 05/03/2016] [Indexed: 11/22/2022] Open
Abstract
Pollination by insects is essential to many ecosystems. Previously, we have shown that floral scent is important to mediate pollen transfer between plants (Kessler et al., 2015). Yet, the mechanisms by which pollinators evaluate volatiles of single flowers remained unclear. Here, Nicotiana attenuata plants, in which floral volatiles have been genetically silenced and its hawkmoth pollinator, Manduca sexta, were used in semi-natural tent and wind-tunnel assays to explore the function of floral scent. We found that floral scent functions to increase the fitness of individual flowers not only by increasing detectability but also by enhancing the pollinator's foraging efforts. Combining proboscis choice tests with neurophysiological, anatomical and molecular analyses we show that this effect is governed by newly discovered olfactory neurons on the tip of the moth's proboscis. With the tip of their tongue, pollinators assess the advertisement of individual flowers, an ability essential for maintaining this important ecosystem service.
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Affiliation(s)
- Alexander Haverkamp
- Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Felipe Yon
- Department of Molecular Ecology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Ian W Keesey
- Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Christine Mißbach
- Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Christopher Koenig
- Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Bill S Hansson
- Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Ian T Baldwin
- Department of Molecular Ecology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Markus Knaden
- Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Danny Kessler
- Department of Molecular Ecology, Max-Planck Institute for Chemical Ecology, Jena, Germany
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French A, Ali Agha M, Mitra A, Yanagawa A, Sellier MJ, Marion-Poll F. Drosophila Bitter Taste(s). Front Integr Neurosci 2015; 9:58. [PMID: 26635553 PMCID: PMC4658422 DOI: 10.3389/fnint.2015.00058] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 10/30/2015] [Indexed: 11/13/2022] Open
Abstract
Most animals possess taste receptors neurons detecting potentially noxious compounds. In humans, the ligands which activate these neurons define a sensory space called “bitter”. By extension, this term has been used in animals and insects to define molecules which induce aversive responses. In this review, based on our observations carried out in Drosophila, we examine how bitter compounds are detected and if bitter-sensitive neurons respond only to molecules bitter to humans. Like most animals, flies detect bitter chemicals through a specific population of taste neurons, distinct from those responding to sugars or to other modalities. Activating bitter-sensitive taste neurons induces aversive reactions and inhibits feeding. Bitter molecules also contribute to the suppression of sugar-neuron responses and can lead to a complete inhibition of the responses to sugar at the periphery. Since some bitter molecules activate bitter-sensitive neurons and some inhibit sugar detection, bitter molecules are represented by two sensory spaces which are only partially congruent. In addition to molecules which impact feeding, we recently discovered that the activation of bitter-sensitive neurons also induces grooming. Bitter-sensitive neurons of the wings and of the legs can sense chemicals from the gram negative bacteria, Escherichia coli, thus adding another biological function to these receptors. Bitter-sensitive neurons of the proboscis also respond to the inhibitory pheromone, 7-tricosene. Activating these neurons by bitter molecules in the context of sexual encounter inhibits courting and sexual reproduction, while activating these neurons with 7-tricosene in a feeding context will inhibit feeding. The picture that emerges from these observations is that the taste system is composed of detectors which monitor different “categories” of ligands, which facilitate or inhibit behaviors depending on the context (feeding, sexual reproduction, hygienic behavior), thus considerably extending the initial definition of “bitter” tasting.
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Affiliation(s)
- Alice French
- Evolution, Génomes, Comportement & Ecologie, CNRS, IRD, Université Paris-Sud, Université Paris-Saclay Gif-sur-Yvette, France
| | - Moutaz Ali Agha
- Evolution, Génomes, Comportement & Ecologie, CNRS, IRD, Université Paris-Sud, Université Paris-Saclay Gif-sur-Yvette, France
| | - Aniruddha Mitra
- Evolution, Génomes, Comportement & Ecologie, CNRS, IRD, Université Paris-Sud, Université Paris-Saclay Gif-sur-Yvette, France
| | - Aya Yanagawa
- Evolution, Génomes, Comportement & Ecologie, CNRS, IRD, Université Paris-Sud, Université Paris-Saclay Gif-sur-Yvette, France ; Research Institute for Sustainable Humanosphere, Kyoto University Uji City, Japan
| | - Marie-Jeanne Sellier
- Evolution, Génomes, Comportement & Ecologie, CNRS, IRD, Université Paris-Sud, Université Paris-Saclay Gif-sur-Yvette, France
| | - Frédéric Marion-Poll
- Evolution, Génomes, Comportement & Ecologie, CNRS, IRD, Université Paris-Sud, Université Paris-Saclay Gif-sur-Yvette, France ; AgroParisTech Paris, France
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