1
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Asefa WR, Woo JN, Kim SY, Choi H, Sung H, Choi MS, Choi M, Yoon SE, Kim YJ, Suh BC, Kang K, Kwon JY. Molecular and cellular basis of sodium sensing in Drosophila labellum. iScience 2024; 27:110248. [PMID: 39015148 PMCID: PMC11250893 DOI: 10.1016/j.isci.2024.110248] [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: 11/12/2023] [Revised: 03/14/2024] [Accepted: 06/07/2024] [Indexed: 07/18/2024] Open
Abstract
Appropriate ingestion of salt is essential for physiological processes such as ionic homeostasis and neuronal activity. Generally, low concentrations of salt elicit attraction, while high concentrations elicit aversive responses. Here, we observed that sugar neurons in the L sensilla of the Drosophila labellum cf. responses to NaCl, while sugar neurons in the S-c sensilla do not respond to NaCl, suggesting that gustatory receptor neurons involved in NaCl sensing may employ diverse molecular mechanisms. Through an RNAi screen of the entire Ir and ppk gene families and molecular genetic approaches, we identified IR76b, IR25a, and IR56b as necessary components for NaCl sensing in the Drosophila labellum. Co-expression of these three IRs in heterologous systems such as S2 cells or Xenopus oocytes resulted in a current in response to sodium stimulation, suggesting formation of a sodium-sensing complex. Our results should provide insights for research on the diverse combinations constituting salt receptor complexes.
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Affiliation(s)
- Wayessa Rahel Asefa
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jin-Nyeong Woo
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Seon Yeong Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
- Neurovascular Unit Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
| | - Hyungjun Choi
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Hayeon Sung
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Department of Molecular, Cellular and Developmental Biology, College of Literature, Science, and the Arts, The University of Michigan, Ann Arbor, USA
| | - Min Sung Choi
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Minkook Choi
- Department of Oral Biology, Yonsei University College of Dentistry, Seoul 03722, Republic of Korea
| | - Sung-Eun Yoon
- Korea Drosophila Resource Center, Gwangju 61005, Republic of Korea
| | - Young-Joon Kim
- Korea Drosophila Resource Center, Gwangju 61005, Republic of Korea
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Byung-Chang Suh
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - KyeongJin Kang
- Neurovascular Unit Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
| | - Jae Young Kwon
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea
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2
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Arntsen C, Guillemin J, Audette K, Stanley M. Tastant-receptor interactions: insights from the fruit fly. Front Nutr 2024; 11:1394697. [PMID: 38665300 PMCID: PMC11043608 DOI: 10.3389/fnut.2024.1394697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 04/02/2024] [Indexed: 04/28/2024] Open
Abstract
Across species, taste provides important chemical information about potential food sources and the surrounding environment. As details about the chemicals and receptors responsible for gustation are discovered, a complex view of the taste system is emerging with significant contributions from research using the fruit fly, Drosophila melanogaster, as a model organism. In this brief review, we summarize recent advances in Drosophila gustation and their relevance to taste research more broadly. Our goal is to highlight the molecular mechanisms underlying the first step of gustatory circuits: ligand-receptor interactions in primary taste cells. After an introduction to the Drosophila taste system and how it encodes the canonical taste modalities sweet, bitter, and salty, we describe recent insights into the complex nature of carboxylic acid and amino acid detection in the context of sour and umami taste, respectively. Our analysis extends to non-canonical taste modalities including metals, fatty acids, and bacterial components, and highlights unexpected receptors and signaling pathways that have recently been identified in Drosophila taste cells. Comparing the intricate molecular and cellular underpinnings of how ligands are detected in vivo in fruit flies reveals both specific and promiscuous receptor selectivity for taste encoding. Throughout this review, we compare and contextualize these Drosophila findings with mammalian research to not only emphasize the conservation of these chemosensory systems, but to demonstrate the power of this model organism in elucidating the neurobiology of taste and feeding.
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Affiliation(s)
| | | | | | - Molly Stanley
- Department of Biology, University of Vermont, Burlington, VT, United States
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3
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Sang J, Dhakal S, Shrestha B, Nath DK, Kim Y, Ganguly A, Montell C, Lee Y. A single pair of pharyngeal neurons functions as a commander to reject high salt in Drosophila melanogaster. eLife 2024; 12:RP93464. [PMID: 38573740 PMCID: PMC10994663 DOI: 10.7554/elife.93464] [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: 04/05/2024] Open
Abstract
Salt (NaCl), is an essential nutrient for survival, while excessive salt can be detrimental. In the fruit fly, Drosophila melanogaster, internal taste organs in the pharynx are critical gatekeepers impacting the decision to accept or reject a food. Currently, our understanding of the mechanism through which pharyngeal gustatory receptor neurons (GRNs) sense high salt are rudimentary. Here, we found that a member of the ionotropic receptor family, Ir60b, is expressed exclusively in a pair of GRNs activated by high salt. Using a two-way choice assay (DrosoX) to measure ingestion volume, we demonstrate that IR60b and two co-receptors IR25a and IR76b are required to prevent high salt consumption. Mutants lacking external taste organs but retaining the internal taste organs in the pharynx exhibit much higher salt avoidance than flies with all taste organs but missing the three IRs. Our findings highlight the vital role for IRs in a pharyngeal GRN to control ingestion of high salt.
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Affiliation(s)
- Jiun Sang
- Department of Bio and Fermentation Convergence Technology, Kookmin UniversitySeoulRepublic of Korea
| | - Subash Dhakal
- Department of Bio and Fermentation Convergence Technology, Kookmin UniversitySeoulRepublic of Korea
| | - Bhanu Shrestha
- Department of Bio and Fermentation Convergence Technology, Kookmin UniversitySeoulRepublic of Korea
| | - Dharmendra Kumar Nath
- Department of Bio and Fermentation Convergence Technology, Kookmin UniversitySeoulRepublic of Korea
| | - Yunjung Kim
- Department of Bio and Fermentation Convergence Technology, Kookmin UniversitySeoulRepublic of Korea
| | - Anindya Ganguly
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa BarbaraSanta BarbaraUnited States
| | - Craig Montell
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa BarbaraSanta BarbaraUnited States
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin UniversitySeoulRepublic of Korea
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4
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Montanari M, Manière G, Berthelot-Grosjean M, Dusabyinema Y, Gillet B, Grosjean Y, Kurz CL, Royet J. Larval microbiota primes the Drosophila adult gustatory response. Nat Commun 2024; 15:1341. [PMID: 38351056 PMCID: PMC10864365 DOI: 10.1038/s41467-024-45532-4] [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] [Received: 03/06/2023] [Accepted: 01/25/2024] [Indexed: 02/16/2024] Open
Abstract
The survival of animals depends, among other things, on their ability to identify threats in their surrounding environment. Senses such as olfaction, vision and taste play an essential role in sampling their living environment, including microorganisms, some of which are potentially pathogenic. This study focuses on the mechanisms of detection of bacteria by the Drosophila gustatory system. We demonstrate that the peptidoglycan (PGN) that forms the cell wall of bacteria triggers an immediate feeding aversive response when detected by the gustatory system of adult flies. Although we identify ppk23+ and Gr66a+ gustatory neurons as necessary to transduce fly response to PGN, we demonstrate that they play very different roles in the process. Time-controlled functional inactivation and in vivo calcium imaging demonstrate that while ppk23+ neurons are required in the adult flies to directly transduce PGN signal, Gr66a+ neurons must be functional in larvae to allow future adults to become PGN sensitive. Furthermore, the ability of adult flies to respond to bacterial PGN is lost when they hatch from larvae reared under axenic conditions. Recolonization of germ-free larvae, but not adults, with a single bacterial species, Lactobacillus brevis, is sufficient to restore the ability of adults to respond to PGN. Our data demonstrate that the genetic and environmental characteristics of the larvae are essential to make the future adults competent to respond to certain sensory stimuli such as PGN.
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Affiliation(s)
| | - Gérard Manière
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAe, Université Bourgogne, F-21000, Dijon, France
| | - Martine Berthelot-Grosjean
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAe, Université Bourgogne, F-21000, Dijon, France
| | - Yves Dusabyinema
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR5242, F-69007, Lyon, France
| | - Benjamin Gillet
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR5242, F-69007, Lyon, France
| | - Yaël Grosjean
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRAe, Université Bourgogne, F-21000, Dijon, France
| | - C Léopold Kurz
- Aix-Marseille Université, CNRS, IBDM, Marseille, France.
| | - Julien Royet
- Aix-Marseille Université, CNRS, IBDM, Marseille, France.
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5
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Toshima N, Schleyer M. IR76b-expressing neurons in Drosophila melanogaster are necessary for associative reward learning of an amino acid mixture. Biol Lett 2024; 20:20230519. [PMID: 38351746 PMCID: PMC10865000 DOI: 10.1098/rsbl.2023.0519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024] Open
Abstract
Learning where to find nutrients while at the same time avoiding toxic food is essential for survival of any animal. Using Drosophila melanogaster larvae as a study case, we investigate the role of gustatory sensory neurons expressing IR76b for associative learning of amino acids, the building blocks of proteins. We found surprising complexity in the neuronal underpinnings of sensing amino acids, and a functional division of sensory neurons. We found that the IR76b receptor is dispensable for amino acid learning, whereas the neurons expressing IR76b are specifically required for the rewarding but not the punishing effect of amino acids. This unexpected dissociation in neuronal processing of amino acids for different behavioural functions provides a study case for functional divisions of labour in gustatory systems.
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Affiliation(s)
- Naoko Toshima
- Department Genetics of Learning and Memory, Leibniz-Institute for Neurobiology, Magdeburg 39118, Germany
- Institute for the Advancement of Higher Education, Hokkaido University, Sapporo 060-0810, Japan
| | - Michael Schleyer
- Department Genetics of Learning and Memory, Leibniz-Institute for Neurobiology, Magdeburg 39118, Germany
- Institute for the Advancement of Higher Education, Hokkaido University, Sapporo 060-0810, Japan
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6
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Sang J, Dhakal S, Shrestha B, Nath DK, Kim Y, Ganguly A, Montell C, Lee Y. A single pair of pharyngeal neurons functions as a commander to reject high salt in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.17.562703. [PMID: 37904986 PMCID: PMC10614918 DOI: 10.1101/2023.10.17.562703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Salt is an essential nutrient for survival, while excessive NaCl can be detrimental. In the fruit fly, Drosophila melanogaster, internal taste organs in the pharynx are critical gatekeepers impacting the decision to accept or reject a food. Currently, our understanding of the mechanism through which pharyngeal gustatory receptor neurons (GRNs) sense high salt are rudimentary. Here, we found that a member of the ionotropic receptor family, Ir60b, is expressed exclusively in a pair of GRNs activated by high salt. Using a two-way choice assay (DrosoX) to measure ingestion volume, we demonstrate that IR60b and two coreceptors IR25a and IR76b, are required to prevent high salt consumption. Mutants lacking external taste organs but retaining the internal taste organs in the pharynx exhibit much higher salt avoidance than flies with all taste organs but missing the three IRs. Our findings highlight the vital role for IRs in a pharyngeal GRN to control ingestion of high salt.
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Affiliation(s)
- Jiun Sang
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
- These authors contributed equally
| | - Subash Dhakal
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
- These authors contributed equally
| | - Bhanu Shrestha
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
| | - Dharmendra Kumar Nath
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
| | - Yunjung Kim
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
| | - Anindya Ganguly
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA United States
| | - Craig Montell
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA United States
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
- Lead Contract
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7
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Zhang X, Liu Y, Guo M, Sun D, Zhang M, Chu X, Berg BG, Wang G. A female-specific odorant receptor mediates oviposition deterrence in the moth Helicoverpa armigera. Curr Biol 2024; 34:1-11.e4. [PMID: 38091990 DOI: 10.1016/j.cub.2023.11.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/14/2023] [Accepted: 11/10/2023] [Indexed: 01/11/2024]
Abstract
Finding ideal oviposition sites is a task of vital importance for all female insects. To ensure optimal conditions for their progeny, females of herbivorous insects detect not only the odors of a relevant host plant but also chemicals released by eggs, named oviposition-deterring pheromones (ODPs). It is reported that such chemicals play critical roles in suppressing female oviposition behavior; however, the molecular mechanism underlying the detection of egg-derived ODPs remains elusive. Here, we have identified three specific fatty acid methyl esters from the surface of eggs of Helicoverpa armigera serving as ODPs-methyl oleate (C18:1ME), methyl palmitate (C16:0ME), and methyl stearate (C18:0ME). We demonstrated that these ODPs are detected by the receptor, HarmOR56, exclusively expressed in sensilla trichodea on female antennae. To assess the significance of this receptor, we disrupted HarmOR56 in H. armigera using CRISPR-Cas9 and found that mutant females did not respond to the ODPs, neither in behavioral nor in electrophysiological tests. We therefore conclude that HarmOR56 is indispensable for identifying the ODPs. This study explores, for the first time, how a female-specific odorant receptor detects chemicals from conspecific eggs. Our data elucidate the intriguing biological phenomenon of repulsion to conspecific eggs during oviposition and contribute new insight into a female-specific olfactory pathway linked to reproduction.
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Affiliation(s)
- Xiaxuan Zhang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Synthetic Biology Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Yang Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Mengbo Guo
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Synthetic Biology Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Dongdong Sun
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Mengjun Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xi Chu
- Chemosensory lab, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Bente Gunnveig Berg
- Chemosensory lab, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Guirong Wang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Synthetic Biology Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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8
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Zhao Y, Johansson E, Duan J, Han Z, Alenius M. Fat- and sugar-induced signals regulate sweet and fat taste perception in Drosophila. Cell Rep 2023; 42:113387. [PMID: 37934669 PMCID: PMC11212107 DOI: 10.1016/j.celrep.2023.113387] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 08/29/2023] [Accepted: 10/22/2023] [Indexed: 11/09/2023] Open
Abstract
In this study, we investigate the interplay between taste perception and macronutrients. While sugar's and protein's self-regulation of taste perception is known, the role of fat remains unclear. We reveal that in Drosophila, fat overconsumption reduces fatty acid taste in favor of sweet perception. Conversely, sugar intake increases fatty acid perception and suppresses sweet taste. Genetic investigations show that the sugar signal, gut-secreted Hedgehog, suppresses sugar taste and enhances fatty acid perception. Fat overconsumption induces unpaired 2 (Upd2) secretion from adipose tissue to the hemolymph. We reveal taste neurons take up Upd2, which triggers Domeless suppression of fatty acid perception. We further show that the downstream JAK/STAT signaling enhances sweet perception and, via Socs36E, fine-tunes Domeless activity and the fatty acid taste perception. Together, our results show that sugar regulates Hedgehog signaling and fat induces Upd2 signaling to balance nutrient intake and to regulate sweet and fat taste perception.
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Affiliation(s)
- Yunpo Zhao
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | | | - Jianli Duan
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Zhe Han
- Center for Precision Disease Modeling, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mattias Alenius
- Department of Molecular Biology, Umeå University, Umeå, Sweden.
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9
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Dweck HKM, Carlson JR. Diverse mechanisms of taste coding in Drosophila. SCIENCE ADVANCES 2023; 9:eadj7032. [PMID: 37976361 PMCID: PMC10656072 DOI: 10.1126/sciadv.adj7032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/18/2023] [Indexed: 11/19/2023]
Abstract
Taste systems encode chemical cues that drive vital behaviors. We have elucidated noncanonical features of taste coding using an unconventional kind of electrophysiological analysis. We find that taste neurons of Drosophila are much more sensitive than previously thought. They have a low spontaneous firing frequency that depends on taste receptors. Taste neurons have a dual function as olfactory neurons: They are activated by most tested odorants, including N,N-diethyl-meta-toluamide (DEET), at a distance. DEET can also inhibit certain taste neurons, revealing that there are two modes of taste response: activation and inhibition. We characterize electrophysiological OFF responses and find that the tastants that elicit them are related in structure. OFF responses link tastant identity to behavior: the magnitude of the OFF response elicited by a tastant correlated with the egg laying behavior it elicited. In summary, the sensitivity and coding capacity of the taste system are much greater than previously known.
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Affiliation(s)
- Hany K M Dweck
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
- Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, CT 06511, USA
| | - John R Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
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10
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Pandey P, Shrestha B, Lee Y. Acid and Alkali Taste Sensation. Metabolites 2023; 13:1131. [PMID: 37999227 PMCID: PMC10673112 DOI: 10.3390/metabo13111131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 11/25/2023] Open
Abstract
Living organisms rely on pH levels for a multitude of crucial biological processes, such as the digestion of food and the facilitation of enzymatic reactions. Among these organisms, animals, including insects, possess specialized taste organs that enable them to discern between acidic and alkaline substances present in their food sources. This ability is vital, as the pH of these compounds directly influences both the nutritional value and the overall health impact of the ingested substances. In response to the various chemical properties of naturally occurring compounds, insects have evolved peripheral taste organs. These sensory structures play a pivotal role in identifying and distinguishing between nourishing and potentially harmful foods. In this concise review, we aim to provide an in-depth examination of the molecular mechanisms governing pH-dependent taste responses, encompassing both acidic and alkaline stimuli, within the peripheral taste organs of the fruit fly, Drosophila melanogaster, drawing insights from a comprehensive analysis of existing research articles.
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Affiliation(s)
| | | | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 02707, Republic of Korea; (P.P.); (B.S.)
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11
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Dey M, Brown E, Charlu S, Keene A, Dahanukar A. Evolution of fatty acid taste in drosophilids. Cell Rep 2023; 42:113297. [PMID: 37864792 PMCID: PMC10697176 DOI: 10.1016/j.celrep.2023.113297] [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] [Received: 02/06/2023] [Revised: 09/01/2023] [Accepted: 10/02/2023] [Indexed: 10/23/2023] Open
Abstract
Comparative studies of related but ecologically distinct species can reveal how the nervous system evolves to drive behaviors that are particularly suited to certain environments. Drosophila melanogaster is a generalist that feeds and oviposits on most overripe fruits. A sibling species, D. sechellia, is an obligate specialist of Morinda citrifolia (noni) fruit, which is rich in fatty acids (FAs). To understand evolution of noni taste preference, we characterized behavioral and cellular responses to noni-associated FAs in three related drosophilids. We find that mixtures of sugar and noni FAs evoke strong aversion in the generalist species but not in D. sechellia. Surveys of taste sensory responses reveal noni FA- and species-specific differences in at least two mechanisms-bitter neuron activation and sweet neuron inhibition-that correlate with shifts in noni preference. Chemoreceptor mutant analysis in D. melanogaster predicts that multiple genetic changes account for evolution of gustatory preference in D. sechellia.
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Affiliation(s)
- Manali Dey
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Elizabeth Brown
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Sandhya Charlu
- Biomedical Sciences Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Alex Keene
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Anupama Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, CA 92521, USA; Biomedical Sciences Graduate Program, University of California, Riverside, Riverside, CA 92521, USA; Department of Molecular, Cell & Systems Biology, University of California, Riverside, Riverside, CA 92521, USA.
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12
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Ruedenauer FA, Parreño MA, Grunwald Kadow IC, Spaethe J, Leonhardt SD. The ecology of nutrient sensation and perception in insects. Trends Ecol Evol 2023; 38:994-1004. [PMID: 37328389 DOI: 10.1016/j.tree.2023.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 06/18/2023]
Abstract
Insects are equipped with neurological, physiological, and behavioral tools to locate potential food sources and assess their nutritional quality based on volatile and chemotactile cues. We summarize current knowledge on insect taste perception and the different modalities of reception and perception. We suggest that the neurophysiological mechanisms of reception and perception are closely linked to the species-specific ecology of different insects. Understanding these links consequently requires a multidisciplinary approach. We also highlight existing knowledge gaps, especially in terms of the exact ligands of receptors, and provide evidence for a perceptional hierarchy suggesting that insects have adapted their reception and perception to preferentially perceive nutrient stimuli that are important for their fitness.
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Affiliation(s)
- Fabian A Ruedenauer
- Plant-Insect Interactions, Research Department Life Science Systems, TUM School of Life Sciences, Technical University of Munich (TUM), Freising, Germany.
| | - Maria Alejandra Parreño
- Plant-Insect Interactions, Research Department Life Science Systems, TUM School of Life Sciences, Technical University of Munich (TUM), Freising, Germany
| | - Ilona C Grunwald Kadow
- Institute of Physiology II, University of Bonn, University Clinic Bonn (UKB), Bonn, Germany
| | - Johannes Spaethe
- Department of Behavioral Physiology and Sociobiology, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Sara D Leonhardt
- Plant-Insect Interactions, Research Department Life Science Systems, TUM School of Life Sciences, Technical University of Munich (TUM), Freising, Germany
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13
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Yang J, Tang R, Chen S, Chen Y, Yuan K, Huang R, Wang L. Exposure to high-sugar diet induces transgenerational changes in sweet sensitivity and feeding behavior via H3K27me3 reprogramming. eLife 2023; 12:e85365. [PMID: 37698486 PMCID: PMC10558205 DOI: 10.7554/elife.85365] [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] [Received: 12/05/2022] [Accepted: 09/11/2023] [Indexed: 09/13/2023] Open
Abstract
Human health is facing a host of new threats linked to unbalanced diets, including high-sugar diet (HSD), which contributes to the development of both metabolic and behavioral disorders. Studies have shown that diet-induced metabolic dysfunctions can be transmitted to multiple generations of offspring and exert long-lasting health burden. Meanwhile, whether and how diet-induced behavioral abnormalities can be transmitted to the offspring remains largely unclear. Here, we showed that ancestral HSD exposure suppressed sweet sensitivity and feeding behavior in the offspring in Drosophila. These behavioral deficits were transmitted through the maternal germline and companied by the enhancement of H3K27me3 modifications. PCL-PRC2 complex, a major driver of H3K27 trimethylation, was upregulated by ancestral HSD exposure, and disrupting its activity eliminated the transgenerational inheritance of sweet sensitivity and feeding behavior deficits. Elevated H3K27me3 inhibited the expression of a transcriptional factor Cad and suppressed sweet sensitivity of the sweet-sensing gustatory neurons, reshaping the sweet perception and feeding behavior of the offspring. Taken together, we uncovered a novel molecular mechanism underlying behavioral abnormalities spanning multiple generations of offspring upon ancestral HSD exposure, which would contribute to the further understanding of long-term health risk of unbalanced diet.
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Affiliation(s)
- Jie Yang
- Life Sciences Institute, Zhejiang UniversityHangzhouChina
| | - Ruijun Tang
- Hunan Key Laboratory of Molecular Precision Medicine, Department of Neurosurgery, Xiangya Hospital, and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South UniversityChangshaChina
| | - Shiye Chen
- Life Sciences Institute, Zhejiang UniversityHangzhouChina
| | - Yinan Chen
- Life Sciences Institute, Zhejiang UniversityHangzhouChina
| | - Kai Yuan
- Hunan Key Laboratory of Molecular Precision Medicine, Department of Neurosurgery, Xiangya Hospital, and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South UniversityChangshaChina
- The Biobank of Xiangya Hospital, Xiangya Hospital, Central South UniversityChangshaChina
| | - Rui Huang
- Center for Neurointelligence, School of Medicine, Chongqing UniversityChongqingChina
- Institute of Molecular Physiology, Shenzhen Bay LaboratoryShenzhenChina
| | - Liming Wang
- Institute of Molecular Physiology, Shenzhen Bay LaboratoryShenzhenChina
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14
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Toyam T, Yamagishi T, Sato R. The roles of enteroendocrine cell distribution and gustatory receptor expression in regulating peptide hormone secretion in the midgut of Bombyx mori larvae. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2023; 114:e22032. [PMID: 37424326 DOI: 10.1002/arch.22032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/08/2023] [Accepted: 06/15/2023] [Indexed: 07/11/2023]
Abstract
To regulate physiological homeostasis and behavior in Bombyx mori, more than 20 peptide hormones in the midgut of larvae are secreted upon detection of food substances at the lumen. Although it is logical to assume that the timings of peptide hormone secretions are regulated, little is known about the mechanisms. In this study, the distributions of enteroendocrine cells (EECs) producing five peptide hormones and EECs expressing gustatory receptors (Grs), as candidate receptors for luminal food substances and nutrients, were examined via immunostaining in B. mori larvae. Three patterns of peptide hormone distribution were observed. Tachykinin (Tk)- and K5-producing EECs were located throughout the midgut; myosuppressin-producing EECs were located in the middle-to-posterior midgut; and allatostatin C- and CCHamide-2-producing EECs were located in the anterior-to-middle midgut. BmGr4 was expressed in some Tk-producing EECs in the anterior midgut, where food and its digestive products arrived 5 min after feeding began. Enzyme-linked immunosorbent assay (ELISA) revealed secretion of Tk starting approximately 5 min after feeding began, suggesting that food sensing by BmGr4 may regulate Tk secretion. BmGr6 was expressed in a few Tk-producing EECs in the middle-to-posterior midgut, although its significance was unclear. BmGr6 was also expressed in many myosuppressin-producing EECs in the middle midgut, where food and its digestive products arrived 60 min after feeding began. ELISA revealed secretion of myosuppressin starting approximately 60 min after feeding began, suggesting that food sensing by BmGr6 may regulate myosuppressin secretion. Finally, BmGr9 was expressed in many BmK5-producing EECs throughout the midgut, suggesting that BmGr9 may function as a sensor for the secretion of BmK5.
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Affiliation(s)
- Tomoko Toyam
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Takayuki Yamagishi
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
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15
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Pradhan RN, Shrestha B, Lee Y. Molecular Basis of Hexanoic Acid Taste in Drosophila melanogaster. Mol Cells 2023; 46:451-460. [PMID: 37202372 PMCID: PMC10336273 DOI: 10.14348/molcells.2023.0035] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/28/2023] [Accepted: 04/10/2023] [Indexed: 05/20/2023] Open
Abstract
Animals generally prefer nutrients and avoid toxic and harmful chemicals. Recent behavioral and physiological studies have identified that sweet-sensing gustatory receptor neurons (GRNs) in Drosophila melanogaster mediate appetitive behaviors toward fatty acids. Sweet-sensing GRN activation requires the function of the ionotropic receptors IR25a, IR56d, and IR76b, as well as the gustatory receptor GR64e. However, we reveal that hexanoic acid (HA) is toxic rather than nutritious to D. melanogaster. HA is one of the major components of the fruit Morinda citrifolia (noni). Thus, we analyzed the gustatory responses to one of major noni fatty acids, HA, via electrophysiology and proboscis extension response (PER) assay. Electrophysiological tests show this is reminiscent of arginine-mediated neuronal responses. Here, we determined that a low concentration of HA induced attraction, which was mediated by sweet-sensing GRNs, and a high concentration of HA induced aversion, which was mediated by bitter-sensing GRNs. We also demonstrated that a low concentration of HA elicits attraction mainly mediated by GR64d and IR56d expressed by sweet-sensing GRNs, but a high concentration of HA activates three gustatory receptors (GR32a, GR33a, and GR66a) expressed by bitter-sensing GRNs. The mechanism of sensing HA is biphasic in a dose dependent manner. Furthermore, HA inhibit sugar-mediated activation like other bitter compounds. Taken together, we discovered a binary HA-sensing mechanism that may be evolutionarily meaningful in the foraging niche of insects.
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Affiliation(s)
| | - Bhanu Shrestha
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul 02707, Korea
| | - Youngseok Lee
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul 02707, Korea
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16
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Shrestha B, Aryal B, Lee Y. The taste of vitamin C in Drosophila. EMBO Rep 2023; 24:e56319. [PMID: 37114473 PMCID: PMC10240197 DOI: 10.15252/embr.202256319] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 04/04/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Vitamins are essential micronutrients, but the mechanisms of vitamin chemoreception in animals are poorly understood. Here, we provide evidence that vitamin C doubles starvation resistance and induces egg laying in Drosophila melanogaster. Our behavioral analyses of genetically engineered and anatomically ablated flies show that fruit flies sense vitamin C via sweet-sensing gustatory receptor neurons (GRNs) in the labellum. Using a behavioral screen and in vivo electrophysiological analyses of ionotropic receptors (IRs) and sweet-sensing gustatory receptors (GRs), we find that two broadly tuned IRs (i.e., IR25a and IR76b) and five GRs (i.e., GR5a, GR61a, GR64b, GR64c, and GR64e) are essential for vitamin C detection. Thus, vitamin C is directly detected by the fly labellum and requires at least two distinct receptor types. Next, we expand our electrophysiological study to test attractive tastants such as sugars, carboxylic acids, and glycerol. Our analysis elucidates the molecular basis of chemoreception in sweet-sensing GRNs.
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Affiliation(s)
- Bhanu Shrestha
- Department of Bio & Fermentation Convergence TechnologyKookmin UniversitySeoulKorea
| | - Binod Aryal
- Department of Bio & Fermentation Convergence TechnologyKookmin UniversitySeoulKorea
| | - Youngseok Lee
- Department of Bio & Fermentation Convergence TechnologyKookmin UniversitySeoulKorea
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17
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Álvarez-Ocaña R, Shahandeh MP, Ray V, Auer TO, Gompel N, Benton R. Odor-regulated oviposition behavior in an ecological specialist. Nat Commun 2023; 14:3041. [PMID: 37236992 DOI: 10.1038/s41467-023-38722-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Colonization of a novel ecological niche can require, or be driven by, evolution of an animal's behaviors promoting their reproductive success. We investigated the evolution and sensory basis of oviposition in Drosophila sechellia, a close relative of Drosophila melanogaster that exhibits extreme specialism for Morinda citrifolia noni fruit. D. sechellia produces fewer eggs than other drosophilids and lays these almost exclusively on noni substrates. We show that visual, textural and social cues do not explain this species-specific preference. By contrast, we find that loss of olfactory input in D. sechellia, but not D. melanogaster, essentially abolishes egg-laying, suggesting that olfaction gates gustatory-driven noni preference. Noni odors are detected by redundant olfactory pathways, but we discover a role for hexanoic acid and the cognate Ionotropic receptor 75b (Ir75b) in odor-evoked oviposition. Through receptor exchange in D. melanogaster, we provide evidence for a causal contribution of odor-tuning changes in Ir75b to the evolution of D. sechellia's oviposition behavior.
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Affiliation(s)
- Raquel Álvarez-Ocaña
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Michael P Shahandeh
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Vijayaditya Ray
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152, Planegg-Martinsried, Germany
| | - Thomas O Auer
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Nicolas Gompel
- Evolutionary Ecology, Ludwig-Maximilians Universität München, Fakultät für Biologie, Biozentrum, Grosshaderner Strasse 2, 82152, Planegg-Martinsried, Germany
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland.
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18
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Li X, Sun Y, Gao S, Li Y, Liu L, Zhu Y. Taste coding of heavy metal ion-induced avoidance in Drosophila. iScience 2023; 26:106607. [PMID: 37128604 PMCID: PMC10148117 DOI: 10.1016/j.isci.2023.106607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 01/04/2023] [Accepted: 03/30/2023] [Indexed: 05/03/2023] Open
Abstract
Increasing pollution of heavy metals poses great risks to animals globally. Their survival likely relies on an ability to detect and avoid harmful heavy metal ions (HMIs). Currently, little is known about the neural mechanisms of HMI detection. Here, we show that Drosophila and related species of Drosophilidae actively avoid toxic HMIs at micromolar concentrations. The high sensitivity to HMIs is biologically relevant. Particularly, their sensitivity to cadmium is as high as that to the most bitter substance, denatonium. Detection of HMIs in food requires Gr66a + gustatory neurons but is independent of bitter-taste receptors. In these neurons, the ionotropic receptors IR76b, IR25a, and IR7a are required for the perception of heavy metals. Furthermore, IR47a mediates the activation of a distinct group of non-Gr66a + gustatory neurons elicited by HMIs. Together, our findings reveal a surprising taste quality represented by noxious metal ions.
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Affiliation(s)
- Xiaonan Li
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanjie Sun
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shan Gao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Li
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Liu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Zhu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
- Corresponding author
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19
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Zhang R, Lun X, Zhang Y, Zhao Y, Xu X, Zhang Z. Characterization of Ionotropic Receptor Gene EonuIR25a in the Tea Green Leafhopper, Empoasca onukii Matsuda. PLANTS (BASEL, SWITZERLAND) 2023; 12:2034. [PMID: 37653951 PMCID: PMC10223087 DOI: 10.3390/plants12102034] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/14/2023] [Accepted: 05/15/2023] [Indexed: 09/02/2023]
Abstract
Ionotropic receptors (IRs) play a central role in detecting chemosensory information from the environment and guiding insect behaviors and are potential target genes for pest control. Empoasca onukii Matsuda is a major pest of the tea plant Camellia sinensis (L.) O. Ktze, and seriously influences tea yields and quality. In this study, the ionotropic receptor gene EonuIR25a in E. onukii was cloned, and the expression pattern of EonuIR25a was detected in various tissues. Behavioral responses of E. onukii to volatile compounds emitted by tea plants were determined using olfactometer bioassay and field trials. To further explore the function of EonuIR25a in olfactory recognition of compounds, RNA interference (RNAi) of EonuIR25a was carried out by ingestion of in vitro synthesized dsRNAs. The coding sequence (CDS) length of EonuIR25a was 1266 bp and it encoded a 48.87 kD protein. EonuIR25a was enriched in the antennae of E. onukii. E. onukii was more significantly attracted by 1-phenylethanol at a concentration of 100 µL/mL. Feeding with dsEonuIR25a significantly downregulated the expression level of EonuIR25a, after 3 h of treatment, which disturbed the behavioral responses of E. onukii to 1-phenylethanol at a concentration of 100 µL/mL. The response rate of E. onukii to 1-phenylethanol was significantly decreased after dsEonuIR25a treatment for 12 h. In summary, the ionotropic receptor gene EonuIR25a was highly expressed in the antennae of E. onukii and was involved in olfactory recognition of the tea plant volatile 1-phenylethanol. The present study may help us to use the ionotropic receptor gene as a target for the behavioral manipulation of E. onukii in the future.
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Affiliation(s)
- Ruirui Zhang
- College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271000, China; (R.Z.)
| | - Xiaoyue Lun
- College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271000, China; (R.Z.)
| | - Yu Zhang
- College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271000, China; (R.Z.)
| | - Yunhe Zhao
- College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271000, China; (R.Z.)
| | - Xiuxiu Xu
- Tea Research Institute, Shandong Academy of Agricultural Science, Ji’nan 250100, China
| | - Zhengqun Zhang
- College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271000, China; (R.Z.)
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20
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Benton R, Dahanukar A. Chemosensory Coding in Drosophila Single Sensilla. Cold Spring Harb Protoc 2023; 2023:107803-pdb.top. [PMID: 36446528 DOI: 10.1101/pdb.top107803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The chemical senses-smell and taste-detect and discriminate an enormous diversity of environmental stimuli and provide fascinating but challenging models to investigate how sensory cues are represented in the brain. Important stimulus-coding events occur in peripheral sensory neurons, which express specific combinations of chemosensory receptors with defined ligand-response profiles. These receptors convert ligand recognition into spatial and temporal patterns of neural activity that are transmitted to, and interpreted in, central brain regions. Drosophila melanogaster provides an attractive model to study chemosensory coding because it possesses relatively simple peripheral olfactory and gustatory systems that display many organizational parallels to those of vertebrates. Moreover, nearly all peripheral chemosensory neurons have been molecularly characterized and are accessible for physiological analysis, as they are exposed on the surface of sensory organs housed in specialized hairs called sensilla. Here, we briefly review anatomical, molecular, and physiological properties of adult Drosophila olfactory and gustatory systems and provide background to methods for electrophysiological recordings of ligand-evoked activity from different types of chemosensory sensilla.
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Affiliation(s)
- Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Anupama Dahanukar
- Department of Molecular, Cell & Systems Biology, University of California, Riverside, California 92521, USA
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21
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Mi T, Mack JO, Koolmees W, Lyon Q, Yochimowitz L, Teng ZQ, Jiang P, Montell C, Zhang YV. Alkaline taste sensation through the alkaliphile chloride channel in Drosophila. Nat Metab 2023; 5:466-480. [PMID: 36941450 PMCID: PMC10665042 DOI: 10.1038/s42255-023-00765-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 02/09/2023] [Indexed: 03/23/2023]
Abstract
The sense of taste is an important sentinel governing what should or should not be ingested by an animal, with high pH sensation playing a critical role in food selection. Here we explore the molecular identities of taste receptors detecting the basic pH of food using Drosophila melanogaster as a model. We identify a chloride channel named alkaliphile (Alka), which is both necessary and sufficient for aversive taste responses to basic food. Alka forms a high-pH-gated chloride channel and is specifically expressed in a subset of gustatory receptor neurons (GRNs). Optogenetic activation of alka-expressing GRNs is sufficient to suppress attractive feeding responses to sucrose. Conversely, inactivation of these GRNs causes severe impairments in the aversion to high pH. Altogether, our discovery of Alka as an alkaline taste receptor lays the groundwork for future research on alkaline taste sensation in other animals.
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Affiliation(s)
- Tingwei Mi
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | - John O Mack
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | | | - Quinn Lyon
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | | | - Zhao-Qian Teng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, China
| | - Peihua Jiang
- Monell Chemical Senses Center, Philadelphia, PA, USA
| | - Craig Montell
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Yali V Zhang
- Monell Chemical Senses Center, Philadelphia, PA, USA.
- Department of Physiology, The Diabetes Research Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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22
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Oxalic Acid Inhibits Feeding Behavior of the Brown Planthopper via Binding to Gustatory Receptor Gr23a. Cells 2023; 12:cells12050771. [PMID: 36899907 PMCID: PMC10001216 DOI: 10.3390/cells12050771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 03/05/2023] Open
Abstract
Plants produce diverse secondary compounds as natural protection against microbial and insect attack. Most of these compounds, including bitters and acids, are sensed by insect gustatory receptors (Grs). Although some organic acids are attractive at low or moderate levels, most acidic compounds are potentially toxic to insects and repress food consumption at high concentrations. At present, the majority of the reported sour receptors function in appetitive behaviors rather than aversive taste responses. Here, using two different heterologous expression systems, the insect Sf9 cell line and the mammalian HEK293T cell line, we started from crude extracts of rice (Oryza sativa) and successfully identified oxalic acid (OA) as a ligand of NlGr23a, a Gr in the brown planthopper Nilaparvata lugens that feeds solely on rice. The antifeedant effect of OA on the brown planthopper was dose dependent, and NlGr23a mediated the repulsive responses to OA in both rice plants and artificial diets. To our knowledge, OA is the first identified ligand of Grs starting from plant crude extracts. These findings on rice-planthopper interactions will be of broad interest for pest control in agriculture and also for better understanding of how insects select host plants.
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23
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Molecular sensors in the taste system of Drosophila. Genes Genomics 2023; 45:693-707. [PMID: 36828965 DOI: 10.1007/s13258-023-01370-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 02/08/2023] [Indexed: 02/26/2023]
Abstract
BACKGROUND Most animals, including humans and insects, consume foods based on their senses. Feeding is mostly regulated by taste and smell. Recent insect studies shed insight into the cross-talk between taste and smell, sweetness and temperature, sweetness and texture, and other sensory modality pairings. Five canonical tastes include sweet, umami, bitter, salty, and sour. Furthermore, other receptors that mediate the detection of noncanonical sensory attributes encoded by taste stimuli, such as Ca2+, Zn2+, Cu2+, lipid, and carbonation, have been characterized. Deorphanizing receptors and interactions among different modalities are expanding the taste field. METHODS Our study explores the taste system of Drosophila melanogaster and perception processing in insects to broaden the neuroscience of taste. Attractive and aversive taste cues and their chemoreceptors are categorized as tables. In addition, we summarize the recent progress in animal behavior as affected by the integration of multisensory information in relation to different gustatory receptor neuronal activations, olfaction, texture, and temperature. We mainly focus on peripheral responses and insect decision-making. CONCLUSION Drosophila is an excellent model animal to study the cellular and molecular mechanism of the taste system. Despite the divergence in the receptors to detect chemicals, taste research in the fruit fly can offer new insights into the many different taste sensors of animals and how to test the interaction among different sensory modalities.
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24
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Reisenman CE, Wong J, Vedagarbha N, Livelo C, Scott K. Taste adaptations associated with host specialization in the specialist Drosophila sechellia. J Exp Biol 2023; 226:jeb244641. [PMID: 36637369 PMCID: PMC10088416 DOI: 10.1242/jeb.244641] [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] [Received: 06/08/2022] [Accepted: 01/09/2023] [Indexed: 01/14/2023]
Abstract
Chemosensory-driven host plant specialization is a major force mediating insect ecological adaptation and speciation. Drosophila sechellia, a species endemic to the Seychelles islands, feeds and oviposits on Morinda citrifolia almost exclusively. This fruit is harmless to D. sechellia but toxic to other Drosophilidae, including the closely related generalists D. simulans and D. melanogaster, because of its high content of fatty acids. While several olfactory adaptations mediating D. sechellia's preference for its host have been uncovered, the role of taste has been much less examined. We found that D. sechellia has reduced taste and feeding aversion to bitter compounds and host fatty acids that are aversive to D. melanogaster and D. simulans. The loss of aversion to canavanine, coumarin and fatty acids arose in the D. sechellia lineage, as its sister species D. simulans showed responses akin to those of D. melanogaster. Drosophila sechellia has increased taste and feeding responses towards M. citrifolia. These results are in line with D. sechellia's loss of genes that encode bitter gustatory receptors (GRs) in D. melanogaster. We found that two GR genes which are lost in D. sechellia, GR39a.a and GR28b.a, influence the reduction of aversive responses to some bitter compounds. Also, D. sechellia has increased appetite for a prominent host fatty acid compound that is toxic to its relatives. Our results support the hypothesis that changes in the taste system, specifically a reduction of sensitivity to bitter compounds that deter generalist ancestors, contribute to the specialization of D. sechellia for its host.
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Affiliation(s)
- Carolina E. Reisenman
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
- Essig Museum of Entomology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Joshua Wong
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
| | - Namrata Vedagarbha
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
| | | | - Kristin Scott
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA
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25
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Deere JU, Sarkissian AA, Yang M, Uttley HA, Martinez Santana N, Nguyen L, Ravi K, Devineni AV. Selective integration of diverse taste inputs within a single taste modality. eLife 2023; 12:e84856. [PMID: 36692370 PMCID: PMC9873257 DOI: 10.7554/elife.84856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/10/2023] [Indexed: 01/25/2023] Open
Abstract
A fundamental question in sensory processing is how different channels of sensory input are processed to regulate behavior. Different input channels may converge onto common downstream pathways to drive the same behaviors, or they may activate separate pathways to regulate distinct behaviors. We investigated this question in the Drosophila bitter taste system, which contains diverse bitter-sensing cells residing in different taste organs. First, we optogenetically activated subsets of bitter neurons within each organ. These subsets elicited broad and highly overlapping behavioral effects, suggesting that they converge onto common downstream pathways, but we also observed behavioral differences that argue for biased convergence. Consistent with these results, transsynaptic tracing revealed that bitter neurons in different organs connect to overlapping downstream pathways with biased connectivity. We investigated taste processing in one type of downstream bitter neuron that projects to the higher brain. These neurons integrate input from multiple organs and regulate specific taste-related behaviors. We then traced downstream circuits, providing the first glimpse into taste processing in the higher brain. Together, these results reveal that different bitter inputs are selectively integrated early in the circuit, enabling the pooling of information, while the circuit then diverges into multiple pathways that may have different roles.
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Affiliation(s)
- Julia U Deere
- Zuckerman Mind Brain Behavior Institute, Columbia UniversityNew YorkUnited States
| | | | - Meifeng Yang
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Hannah A Uttley
- Zuckerman Mind Brain Behavior Institute, Columbia UniversityNew YorkUnited States
| | | | - Lam Nguyen
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Kaushiki Ravi
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Anita V Devineni
- Zuckerman Mind Brain Behavior Institute, Columbia UniversityNew YorkUnited States
- Neuroscience Graduate Program, Emory UniversityAtlantaUnited States
- Department of Biology, Emory UniversityAtlantaUnited States
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26
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Jaime-Lara RB, Brooks BE, Vizioli C, Chiles M, Nawal N, Ortiz-Figueroa RSE, Livinski AA, Agarwal K, Colina-Prisco C, Iannarino N, Hilmi A, Tejeda HA, Joseph PV. A systematic review of the biological mediators of fat taste and smell. Physiol Rev 2023; 103:855-918. [PMID: 36409650 PMCID: PMC9678415 DOI: 10.1152/physrev.00061.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Taste and smell play a key role in our ability to perceive foods. Overconsumption of highly palatable energy-dense foods can lead to increased caloric intake and obesity. Thus there is growing interest in the study of the biological mediators of fat taste and associated olfaction as potential targets for pharmacologic and nutritional interventions in the context of obesity and health. The number of studies examining mechanisms underlying fat taste and smell has grown rapidly in the last 5 years. Therefore, the purpose of this systematic review is to summarize emerging evidence examining the biological mechanisms of fat taste and smell. A literature search was conducted of studies published in English between 2014 and 2021 in adult humans and animal models. Database searches were conducted using PubMed, EMBASE, Scopus, and Web of Science for key terms including fat/lipid, taste, and olfaction. Initially, 4,062 articles were identified through database searches, and a total of 84 relevant articles met inclusion and exclusion criteria and are included in this review. Existing literature suggests that there are several proteins integral to fat chemosensation, including cluster of differentiation 36 (CD36) and G protein-coupled receptor 120 (GPR120). This systematic review will discuss these proteins and the signal transduction pathways involved in fat detection. We also review neural circuits, key brain regions, ingestive cues, postingestive signals, and genetic polymorphism that play a role in fat perception and consumption. Finally, we discuss the role of fat taste and smell in the context of eating behavior and obesity.
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Affiliation(s)
- Rosario B. Jaime-Lara
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Brianna E. Brooks
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Carlotta Vizioli
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Mari Chiles
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland,4Section of Neuromodulation and Synaptic Integration, Division of Intramural Research, National Institute of Mental Health, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Nafisa Nawal
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Rodrigo S. E. Ortiz-Figueroa
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Alicia A. Livinski
- 3NIH Library, Office of Research Services, Office of the Director, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Khushbu Agarwal
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Claudia Colina-Prisco
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Natalia Iannarino
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Aliya Hilmi
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Hugo A. Tejeda
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland
| | - Paule V. Joseph
- 1Section of Sensory Science and Metabolism Unit, Division of Intramural Research, National Institutes of Health, National Institute of Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, Bethesda, Maryland,2Section of Sensory Science and Metabolism, Division of Intramural Research, National Institute of Nursing Research, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland
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27
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Dey M, Ganguly A, Dahanukar A. An inhibitory mechanism for suppressing high salt intake in Drosophila. Chem Senses 2023; 48:bjad014. [PMID: 37201555 PMCID: PMC10413321 DOI: 10.1093/chemse/bjad014] [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] [Received: 08/15/2022] [Indexed: 05/20/2023] Open
Abstract
High concentrations of dietary salt are harmful to health. Like most animals, Drosophila melanogaster are attracted to foods that have low concentrations of salt, but show strong taste avoidance of high salt foods. Salt in known on multiple classes of taste neurons, activating Gr64f sweet-sensing neurons that drive food acceptance and 2 others (Gr66a bitter and Ppk23 high salt) that drive food rejection. Here we find that NaCl elicits a bimodal dose-dependent response in Gr64f taste neurons, which show high activity with low salt and depressed activity with high salt. High salt also inhibits the sugar response of Gr64f neurons, and this action is independent of the neuron's taste response to salt. Consistent with the electrophysiological analysis, feeding suppression in the presence of salt correlates with inhibition of Gr64f neuron activity, and remains if high salt taste neurons are genetically silenced. Other salts such as Na2SO4, KCl, MgSO4, CaCl2, and FeCl3 act on sugar response and feeding behavior in the same way. A comparison of the effects of various salts suggests that inhibition is dictated by the cationic moiety rather than the anionic component of the salt. Notably, high salt-dependent inhibition is not observed in Gr66a neurons-response to a canonical bitter tastant, denatonium, is not altered by high salt. Overall, this study characterizes a mechanism in appetitive Gr64f neurons that can deter ingestion of potentially harmful salts.
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Affiliation(s)
- Manali Dey
- Interdepartmental Neuroscience Program, University of California, Riverside, CA 92521, United States
| | - Anindya Ganguly
- Interdepartmental Neuroscience Program, University of California, Riverside, CA 92521, United States
| | - Anupama Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, CA 92521, United States
- Department of Molecular, Cell & Systems Biology, University of California, Riverside, CA 92521, United States
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28
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Wang W, Dweck HKM, Talross GJS, Zaidi A, Gendron JM, Carlson JR. Sugar sensation and mechanosensation in the egg-laying preference shift of Drosophila suzukii. eLife 2022; 11:e81703. [PMID: 36398882 PMCID: PMC9674340 DOI: 10.7554/elife.81703] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022] Open
Abstract
The agricultural pest Drosophila suzukii differs from most other Drosophila species in that it lays eggs in ripe, rather than overripe, fruit. Previously, we showed that changes in bitter taste sensation accompanied this adaptation (Dweck et al., 2021). Here, we show that D. suzukii has also undergone a variety of changes in sweet taste sensation. D. suzukii has a weaker preference than Drosophila melanogaster for laying eggs on substrates containing all three primary fruit sugars: sucrose, fructose, and glucose. Major subsets of D. suzukii taste sensilla have lost electrophysiological responses to sugars. Expression of several key sugar receptor genes is reduced in the taste organs of D. suzukii. By contrast, certain mechanosensory channel genes, including no mechanoreceptor potential C, are expressed at higher levels in the taste organs of D. suzukii, which has a higher preference for stiff substrates. Finally, we find that D. suzukii responds differently from D. melanogaster to combinations of sweet and mechanosensory cues. Thus, the two species differ in sweet sensation, mechanosensation, and their integration, which are all likely to contribute to the differences in their egg-laying preferences in nature.
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Affiliation(s)
- Wanyue Wang
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Hany KM Dweck
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Gaëlle JS Talross
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Ali Zaidi
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Joshua M Gendron
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - John R Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
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29
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Trautenberg LC, Brankatschk M, Shevchenko A, Wigby S, Reinhardt K. Ecological lipidology. eLife 2022; 11:79288. [PMID: 36069772 PMCID: PMC9451535 DOI: 10.7554/elife.79288] [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: 04/08/2022] [Accepted: 08/11/2022] [Indexed: 11/13/2022] Open
Abstract
Dietary lipids (DLs), particularly sterols and fatty acids, are precursors for endogenous lipids that, unusually for macronutrients, shape cellular and organismal function long after ingestion. These functions – cell membrane structure, intracellular signalling, and hormonal activity – vary with the identity of DLs, and scale up to influence health, survival, and reproductive fitness, thereby affecting evolutionary change. Our Ecological Lipidology approach integrates biochemical mechanisms and molecular cell biology into evolution and nutritional ecology. It exposes our need to understand environmental impacts on lipidomes, the lipid specificity of cell functions, and predicts the evolution of lipid-based diet choices. Broad interdisciplinary implications of Ecological Lipidology include food web alterations, species responses to environmental change, as well as sex differences and lifestyle impacts on human nutrition, and opportunities for DL-based therapies.
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Affiliation(s)
| | - Marko Brankatschk
- Biotechnology Center (BIOTEC), Technische Universität Dresden, Dresden, Germany
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Stuart Wigby
- Applied Zoology, Technische Universität Dresden, Dresden, Germany.,Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Klaus Reinhardt
- Applied Zoology, Technische Universität Dresden, Dresden, Germany
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30
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McDowell SAT, Stanley M, Gordon MD. A molecular mechanism for high salt taste in Drosophila. Curr Biol 2022; 32:3070-3081.e5. [PMID: 35772408 DOI: 10.1016/j.cub.2022.06.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/04/2022] [Accepted: 06/07/2022] [Indexed: 11/25/2022]
Abstract
Dietary salt detection and consumption are crucial to maintaining fluid and ionic homeostasis. To optimize salt intake, animals employ salt-dependent activation of multiple taste pathways. Generally, sodium activates attractive taste cells, but attraction is overridden at high salt concentrations by cation non-selective activation of aversive taste cells. In flies, high salt avoidance is driven by both "bitter" taste neurons and a class of glutamatergic "high salt" neurons expressing pickpocket23 (ppk23). Although the cellular basis of salt taste has been described, many of the molecular mechanisms remain elusive. Here, we show that ionotropic receptor 7c (IR7c) is expressed in glutamatergic high salt neurons, where it functions with co-receptors IR76b and IR25a to detect high salt and is essential for monovalent salt taste. Misexpression of IR7c in sweet neurons, which endogenously express IR76b and IR25a, confers responsiveness to non-sodium salts, indicating that IR7c is sufficient to convert a sodium-selective gustatory receptor neuron to a cation non-selective one. Furthermore, the resultant transformation of taste neuron tuning switches potassium chloride from an aversive to an attractive tastant. This research provides insight into the molecular basis of monovalent and divalent salt-taste coding.
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Affiliation(s)
- Sasha A T McDowell
- Department of Zoology and Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Molly Stanley
- Department of Zoology and Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Michael D Gordon
- Department of Zoology and Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
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31
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Dweck HK, Talross GJ, Luo Y, Ebrahim SA, Carlson JR. Ir56b is an atypical ionotropic receptor that underlies appetitive salt response in Drosophila. Curr Biol 2022; 32:1776-1787.e4. [PMID: 35294865 PMCID: PMC9050924 DOI: 10.1016/j.cub.2022.02.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/08/2022] [Accepted: 02/22/2022] [Indexed: 01/28/2023]
Abstract
Salt taste is one of the most ancient of all sensory modalities. However, the molecular basis of salt taste remains unclear in invertebrates. Here, we show that the response to low, appetitive salt concentrations in Drosophila depends on Ir56b, an atypical member of the ionotropic receptor (Ir) family. Ir56b acts in concert with two coreceptors, Ir25a and Ir76b. Mutation of Ir56b virtually eliminates an appetitive behavioral response to salt. Ir56b is expressed in neurons that also sense sugars via members of the Gr (gustatory receptor) family. Misexpression of Ir56b in bitter-sensing neurons confers physiological responses to appetitive doses of salt. Ir56b is unique among tuning Irs in containing virtually no N-terminal region, a feature that is evolutionarily conserved. Moreover, Ir56b is a "pseudo-pseudogene": its coding sequence contains a premature stop codon that can be replaced with a sense codon without loss of function. This stop codon is conserved among many Drosophila species but is absent in a number of species associated with cactus in arid regions. Thus, Ir56b serves the evolutionarily ancient function of salt detection in neurons that underlie both salt and sweet taste modalities.
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32
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Aryal B, Dhakal S, Shrestha B, Lee Y. Molecular and neuronal mechanisms for amino acid taste perception in the Drosophila labellum. Curr Biol 2022; 32:1376-1386.e4. [PMID: 35176225 DOI: 10.1016/j.cub.2022.01.060] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/19/2021] [Accepted: 01/21/2022] [Indexed: 12/22/2022]
Abstract
Amino acids are essential nutrients that act as building blocks for protein synthesis. Recent studies in Drosophila have demonstrated that glycine, phenylalanine, and threonine elicit attraction, whereas tryptophan elicits aversion at ecologically relevant concentrations. Here, we demonstrated that eight amino acids, including arginine, glycine, alanine, serine, phenylalanine, threonine, cysteine, and proline, differentially stimulate feeding behavior by activating sweet-sensing gustatory receptor neurons (GRNs) in L-type and S-type sensilla. In turn, this process is mediated by three GRs (GR5a, GR61a, and GR64f), as well as two broadly required ionotropic receptors (IRs), IR25a and IR76b. However, GR5a, GR61a, and GR64f are only required for sensing amino acids in the sweet-sensing GRNs of L-type sensilla. This suggests that amino acid sensing in different type sensilla occurs through dual mechanisms. Furthermore, our findings indicated that ecologically relevant high concentrations of arginine, lysine, proline, valine, tryptophan, isoleucine, and leucine elicit aversive responses via bitter-sensing GRNs, which are mediated by three IRs (IR25a, IR51b, and IR76b). More importantly, our results demonstrate that arginine, lysine, and proline induce biphasic responses in a concentration-dependent manner. Therefore, amino acid detection in Drosophila occurs through two classes of receptors that activate two sets of sensory neurons in physiologically distinct pathways, which ultimately mediates attraction or aversion behaviors.
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Affiliation(s)
- Binod Aryal
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul 02707, Republic of Korea
| | - Subash Dhakal
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul 02707, Republic of Korea
| | - Bhanu Shrestha
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul 02707, Republic of Korea
| | - Youngseok Lee
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul 02707, Republic of Korea; Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Republic of Korea.
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33
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Hou XQ, Zhang DD, Powell D, Wang HL, Andersson MN, Löfstedt C. Ionotropic receptors in the turnip moth Agrotis segetum respond to repellent medium-chain fatty acids. BMC Biol 2022; 20:34. [PMID: 35130883 PMCID: PMC8822749 DOI: 10.1186/s12915-022-01235-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 01/19/2022] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In insects, airborne chemical signals are mainly detected by two receptor families, odorant receptors (ORs) and ionotropic receptors (IRs). Functions of ORs have been intensively investigated in Diptera and Lepidoptera, while the functions and evolution of the more ancient IR family remain largely unexplored beyond Diptera. RESULTS Here, we identified a repertoire of 26 IRs from transcriptomes of female and male antennae, and ovipositors in the moth Agrotis segetum. We observed that a large clade formed by IR75p and IR75q expansions is closely related to the acid-sensing IRs identified in Diptera. We functionally assayed each of the five AsegIRs from this clade using Xenopus oocytes and found that two receptors responded to the tested ligands. AsegIR75p.1 responded to several compounds but hexanoic acid was revealed to be the primary ligand, and AsegIR75q.1 responded primarily to octanoic acid, and less so to nonanoic acid. It has been reported that the C6-C10 medium-chain fatty acids repel various insects including many drosophilids and mosquitos. We show that the C6-C10 medium-chain fatty acids elicited antennal responses of both sexes of A. segetum, while only octanoic acid had repellent effect to the moths in a behavioral assay. In addition, using fluorescence in situ hybridization, we demonstrated that the five IRs and their co-receptor AsegIR8a are not located in coeloconic sensilla as found in Drosophila, but in basiconic or trichoid sensilla. CONCLUSIONS Our results significantly expand the current knowledge of the insect IR family. Based on the functional data in combination with phylogenetic analysis, we propose that subfunctionalization after gene duplication plays an important role in the evolution of ligand specificities of the acid-sensing IRs in Lepidoptera.
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Affiliation(s)
- Xiao-Qing Hou
- Department of Biology, Lund University, Sölvegatan 37, 223 62 Lund, Sweden
- Present address: Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Dan-Dan Zhang
- Department of Biology, Lund University, Sölvegatan 37, 223 62 Lund, Sweden
| | - Daniel Powell
- Department of Biology, Lund University, Sölvegatan 37, 223 62 Lund, Sweden
- Present address: Global Change Ecology Research Group, School of Science and Engineering, University of the Sunshine Coast, QLD, Sunshine Coast, Australia
| | - Hong-Lei Wang
- Department of Biology, Lund University, Sölvegatan 37, 223 62 Lund, Sweden
| | | | - Christer Löfstedt
- Department of Biology, Lund University, Sölvegatan 37, 223 62 Lund, Sweden
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34
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Crava CM, Bobkov YV, Sollai G, Anfora G, Crnjar R, Cattaneo AM. Chemosensory Receptors in the Larval Maxilla of Papilio hospiton. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.795994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Among the butterflies of the genus Papilio (Lepidoptera: Papilionidae), Papilio hospiton (Géné) has a geographical distribution limited to the Mediterranean islands of Sardinia (Italy) and Corsica (France). This is mainly due to the host range that includes only a few plant species of Apiaceae and Rutaceae growing on these islands. In a previous electrophysiological investigation conducted on the maxillary gustatory system of larvae of P. hospiton and its closely phylogenetically related species Papilio machaon, a significantly higher spike activity was shown for the gustatory neurons of lateral and medial styloconic sensilla in P. hospiton when bitter compounds were tested. This effect was possibly correlated to the limited host choice range for P. hospiton. To shed light on the molecular aspects of this phenomenon, we investigated the expression pattern of sensory-related sequences by conducting a transcriptomic analysis from total RNA isolates of P. hospiton larval maxillae. We identified several transcripts that may be involved in taste (one gustatory receptor, one divergent ionotropic receptor, and several transient receptor potential channels, TRPs) as well as transcripts supporting an olfactory function for this appendage, including odorant receptors (ORs), antennal ionotropic receptors (A-IRs), sensory neuron membrane proteins (SNMPs), and odorant-binding proteins (OBPs). We used Human Embryonic Kidney (HEK293A) cells to heterologously express two of the identified receptors, PhospOR1 and PhospPain, together with their orthologs from P. machaon, for functional characterization. While our data suggest no activation of these two receptors by the ligands known so far to activate the electrophysiological response in larval maxillary neurons of Papilio species, nor temperature activation of both Papilio TRPA-channel Painless, they represent the first attempt in connecting neuronal activity with their molecular bases to unravel diet specialization between closely related Papilio species.
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35
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A functional division of Drosophila sweet taste neurons that is value-based and task-specific. Proc Natl Acad Sci U S A 2022; 119:2110158119. [PMID: 35031566 PMCID: PMC8784143 DOI: 10.1073/pnas.2110158119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2021] [Indexed: 11/18/2022] Open
Abstract
Sucrose is an attractive feeding substance and a positive reinforcer for Drosophila But Drosophila females have been shown to robustly reject a sucrose-containing option for egg-laying when given a choice between a plain and a sucrose-containing option in specific contexts. How the sweet taste system of Drosophila promotes context-dependent devaluation of an egg-laying option that contains sucrose, an otherwise highly appetitive tastant, is unknown. Here, we report that devaluation of sweetness/sucrose for egg-laying is executed by a sensory pathway recruited specifically by the sweet neurons on the legs of Drosophila First, silencing just the leg sweet neurons caused acceptance of the sucrose option in a sucrose versus plain decision, whereas expressing the channelrhodopsin CsChrimson in them caused rejection of a plain option that was "baited" with light over another that was not. Analogous bidirectional manipulations of other sweet neurons did not produce these effects. Second, circuit tracing revealed that the leg sweet neurons receive different presynaptic neuromodulations compared to some other sweet neurons and were the only ones with postsynaptic partners that projected prominently to the superior lateral protocerebrum (SLP) in the brain. Third, silencing one specific SLP-projecting postsynaptic partner of the leg sweet neurons reduced sucrose rejection, whereas expressing CsChrimson in it promoted rejection of a light-baited option during egg-laying. These results uncover that the Drosophila sweet taste system exhibits a functional division that is value-based and task-specific, challenging the conventional view that the system adheres to a simple labeled-line coding scheme.
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36
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Excessive energy expenditure due to acute physical restraint disrupts Drosophila motivational feeding response. Sci Rep 2021; 11:24208. [PMID: 34921197 PMCID: PMC8683507 DOI: 10.1038/s41598-021-03575-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 12/03/2021] [Indexed: 11/22/2022] Open
Abstract
To study the behavior of Drosophila, it is often necessary to restrain and mount individual flies. This requires removal from food, additional handling, anesthesia, and physical restraint. We find a strong positive correlation between the length of time flies are mounted and their subsequent reflexive feeding response, where one hour of mounting is the approximate motivational equivalent to ten hours of fasting. In an attempt to explain this correlation, we rule out anesthesia side-effects, handling, additional fasting, and desiccation. We use respirometric and metabolic techniques coupled with behavioral video scoring to assess energy expenditure in mounted and free flies. We isolate a specific behavior capable of exerting large amounts of energy in mounted flies and identify it as an attempt to escape from restraint. We present a model where physical restraint leads to elevated activity and subsequent faster nutrient storage depletion among mounted flies. This ultimately further accelerates starvation and thus increases reflexive feeding response. In addition, we show that the consequences of the physical restraint profoundly alter aerobic activity, energy depletion, taste, and feeding behavior, and suggest that careful consideration is given to the time-sensitive nature of these highly significant effects when conducting behavioral, physiological or imaging experiments that require immobilization.
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37
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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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38
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Ugine TA, Krasnoff SB, Behmer ST. Omnivory in predatory lady beetles is widespread and driven by an appetite for sterols. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13965] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Todd A. Ugine
- Department of Entomology Cornell University Ithaca NY USA
| | - Stuart B. Krasnoff
- Emerging Pests and Pathogens Research Unit USDA‐ARSRobert W. Holley Center Ithaca NY USA
| | - Spencer T. Behmer
- Department of Entomology Texas A&M University College Station TX USA
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39
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Vulpe A, Menuz K. Ir76b is a Co-receptor for Amine Responses in Drosophila Olfactory Neurons. Front Cell Neurosci 2021; 15:759238. [PMID: 34867202 PMCID: PMC8635857 DOI: 10.3389/fncel.2021.759238] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/27/2021] [Indexed: 11/22/2022] Open
Abstract
Two large families of olfactory receptors, the Odorant Receptors (ORs) and Ionotropic Receptors (IRs), mediate responses to most odors in the insect olfactory system. Individual odorant binding "tuning" OrX receptors are expressed by olfactory neurons in basiconic and trichoid sensilla and require the co-receptor Orco. The situation for IRs is more complex. Different tuning IrX receptors are expressed by olfactory neurons in coeloconic sensilla and rely on either the Ir25a or Ir8a co-receptors; some evidence suggests that Ir76b may also act as a co-receptor, but its function has not been systematically examined. Surprisingly, recent data indicate that nearly all coeloconic olfactory neurons co-express Ir25a, Ir8a, and Ir76b. Here, we demonstrate that Ir76b and Ir25a function together in all amine-sensing olfactory receptor neurons. In most neurons, loss of either co-receptor abolishes amine responses. In contrast, amine responses persist in the absence of Ir76b or Ir25a in ac1 sensilla but are lost in a double mutant. We show that responses mediated by acid-sensing neurons do not require Ir76b, despite their expression of this co-receptor. Our study also demonstrates that one population of coeloconic olfactory neurons exhibits Ir76b/Ir25a-dependent and Orco-dependent responses to distinct odorants. Together, our data establish the role of Ir76b as a bona fide co-receptor, which acts in partnership with Ir25a. Given that these co-receptors are among the most highly conserved olfactory receptors and are often co-expressed in chemosensory neurons, our data suggest Ir76b and Ir25a also work in tandem in other insects.
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Affiliation(s)
- Alina Vulpe
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Karen Menuz
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
- Connecticut Institute for Brain and Cognitive Sciences, University of Connecticut, Storrs, CT, United States
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40
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Montell C. Drosophila sensory receptors-a set of molecular Swiss Army Knives. Genetics 2021; 217:1-34. [PMID: 33683373 DOI: 10.1093/genetics/iyaa011] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 11/17/2020] [Indexed: 01/01/2023] Open
Abstract
Genetic approaches in the fruit fly, Drosophila melanogaster, have led to a major triumph in the field of sensory biology-the discovery of multiple large families of sensory receptors and channels. Some of these families, such as transient receptor potential channels, are conserved from animals ranging from worms to humans, while others, such as "gustatory receptors," "olfactory receptors," and "ionotropic receptors," are restricted to invertebrates. Prior to the identification of sensory receptors in flies, it was widely assumed that these proteins function in just one modality such as vision, smell, taste, hearing, and somatosensation, which includes thermosensation, light, and noxious mechanical touch. By employing a vast combination of genetic, behavioral, electrophysiological, and other approaches in flies, a major concept to emerge is that many sensory receptors are multitaskers. The earliest example of this idea was the discovery that individual transient receptor potential channels function in multiple senses. It is now clear that multitasking is exhibited by other large receptor families including gustatory receptors, ionotropic receptors, epithelial Na+ channels (also referred to as Pickpockets), and even opsins, which were formerly thought to function exclusively as light sensors. Genetic characterizations of these Drosophila receptors and the neurons that express them also reveal the mechanisms through which flies can accurately differentiate between different stimuli even when they activate the same receptor, as well as mechanisms of adaptation, amplification, and sensory integration. The insights gleaned from studies in flies have been highly influential in directing investigations in many other animal models.
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Affiliation(s)
- Craig Montell
- Department of Molecular, Cellular, and Developmental Biology, The Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
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41
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Chen YCD, Menon V, Joseph RM, Dahanukar AA. Control of Sugar and Amino Acid Feeding via Pharyngeal Taste Neurons. J Neurosci 2021; 41:5791-5808. [PMID: 34031164 PMCID: PMC8265808 DOI: 10.1523/jneurosci.1794-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 05/06/2021] [Accepted: 05/11/2021] [Indexed: 11/21/2022] Open
Abstract
Insect gustatory systems comprise multiple taste organs for detecting chemicals that signal palatable or noxious quality. Although much is known about how taste neurons sense various chemicals, many questions remain about how individual taste neurons in each taste organ control feeding. Here, we use the Drosophila pharynx as a model to investigate how taste information is encoded at the cellular level to regulate consumption of sugars and amino acids. We first generate taste-blind animals and establish a critical role for pharyngeal input in food selection. We then investigate feeding behavior of both male and female flies in which only selected classes of pharyngeal neurons are restored via binary choice feeding preference assays as well as Fly Liquid-Food Interaction Counter assays. We find instances of integration as well as redundancy in how pharyngeal neurons control behavioral responses to sugars and amino acids. Additionally, we find that pharyngeal neurons drive sugar feeding preference based on sweet taste but not on nutritional value. Finally, we demonstrate functional specialization of pharyngeal and external neurons using optogenetic activation. Overall, our genetic taste neuron protection system in a taste-blind background provides a powerful approach to elucidate principles of pharyngeal taste coding and demonstrates functional overlap and subdivision among taste neurons.SIGNIFICANCE STATEMENT Dietary intake of nutritious chemicals such as sugars and amino acids is essential for the survival of an animal. In insects, distinct classes of taste neurons control acceptance or rejection of food sources. Here, we develop a genetic system to investigate how individual taste neurons in the Drosophila pharynx encode specific tastants, focusing on sugars and amino acids. By examining flies in which only a single class of taste neurons is active, we find evidence for functional overlap as well as redundancy in responses to sugars and amino acids. We also uncover a functional subdivision between pharyngeal and external neurons in driving feeding responses. Overall, we find that different pharyngeal neurons act together to control intake of the two categories of appetitive tastants.
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Affiliation(s)
- Yu-Chieh David Chen
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, California 92521
| | - Vaibhav Menon
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, California 92521
| | - Ryan Matthew Joseph
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, California 92521
| | - Anupama Arun Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, California 92521
- Department of Molecular, Cell, and Systems Biology, University of California, Riverside, Riverside, California 92521
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42
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Demi LM, Taylor BW, Reading BJ, Tordoff MG, Dunn RR. Understanding the evolution of nutritive taste in animals: Insights from biological stoichiometry and nutritional geometry. Ecol Evol 2021; 11:8441-8455. [PMID: 34257909 PMCID: PMC8258225 DOI: 10.1002/ece3.7745] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
A major conceptual gap in taste biology is the lack of a general framework for understanding the evolution of different taste modalities among animal species. We turn to two complementary nutritional frameworks, biological stoichiometry theory and nutritional geometry, to develop hypotheses for the evolution of different taste modalities in animals. We describe how the attractive tastes of Na-, Ca-, P-, N-, and C-containing compounds are consistent with principles of both frameworks based on their shared focus on nutritional imbalances and consumer homeostasis. Specifically, we suggest that the evolution of multiple nutritive taste modalities can be predicted by identifying individual elements that are typically more concentrated in the tissues of animals than plants. Additionally, we discuss how consumer homeostasis can inform our understanding of why some taste compounds (i.e., Na, Ca, and P salts) can be either attractive or aversive depending on concentration. We also discuss how these complementary frameworks can help to explain the evolutionary history of different taste modalities and improve our understanding of the mechanisms that lead to loss of taste capabilities in some animal lineages. The ideas presented here will stimulate research that bridges the fields of evolutionary biology, sensory biology, and ecology.
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Affiliation(s)
- Lee M. Demi
- Department of Applied EcologyNorth Carolina State UniversityRaleighNCUSA
| | - Brad W. Taylor
- Department of Applied EcologyNorth Carolina State UniversityRaleighNCUSA
| | | | | | - Robert R. Dunn
- Department of Applied EcologyNorth Carolina State UniversityRaleighNCUSA
- Center for Evolutionary HologenomicsUniversity of CopenhagenCopenhagenDenmark
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43
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Stanley M, Ghosh B, Weiss ZF, Christiaanse J, Gordon MD. Mechanisms of lactic acid gustatory attraction in Drosophila. Curr Biol 2021; 31:3525-3537.e6. [PMID: 34197729 DOI: 10.1016/j.cub.2021.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/30/2021] [Accepted: 06/02/2021] [Indexed: 01/05/2023]
Abstract
Sour has been studied almost exclusively as an aversive taste modality. Yet recent work in Drosophila demonstrates that specific carboxylic acids are attractive at ecologically relevant concentrations. Here, we demonstrate that lactic acid is an appetitive and energetic tastant, which stimulates feeding through activation of sweet gustatory receptor neurons (GRNs). This activation displays distinct, mechanistically separable stimulus onset and removal phases. Ionotropic receptor 25a (IR25a) primarily mediates the onset response, which shows specificity for the lactate anion and drives feeding initiation through proboscis extension. Conversely, sweet gustatory receptors (Gr64a-f) mediate a non-specific removal response to low pH that primarily impacts ingestion. While mutations in either receptor family have marginal impacts on feeding, lactic acid attraction is completely abolished in combined mutants. Thus, specific components of lactic acid are detected through two classes of receptors to activate a single set of sensory neurons in physiologically distinct ways, ultimately leading to robust behavioral attraction.
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Affiliation(s)
- Molly Stanley
- Department of Zoology and Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Britya Ghosh
- Department of Zoology and Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada; Graduate Program in Cell and Developmental Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Zachary F Weiss
- Department of Zoology and Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Jaime Christiaanse
- Department of Zoology and Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Michael D Gordon
- Department of Zoology and Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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44
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Liao S, Amcoff M, Nässel DR. Impact of high-fat diet on lifespan, metabolism, fecundity and behavioral senescence in Drosophila. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 133:103495. [PMID: 33171202 DOI: 10.1016/j.ibmb.2020.103495] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 10/01/2020] [Accepted: 10/30/2020] [Indexed: 06/11/2023]
Abstract
Excess consumption of high-fat diet (HFD) is likely to result in obesity and increases the predisposition to associated health disorders. Drosophila melanogaster has emerged as an important model to study the effects of HFD on metabolism, gut function, behavior, and ageing. In this study, we investigated the effects of HFD on physiology and behavior of female flies at different time-points over several weeks. We found that HFD decreases lifespan, and also with age leads to accelerated decline of climbing ability in both virgins and mated flies. In virgins HFD also increased sleep fragmentation with age. Furthermore, long-term exposure to HFD results in elevated adipokinetic hormone (AKH) transcript levels and an enlarged crop with increased lipid stores. We detected no long-term effects of HFD on body mass, or levels of triacylglycerides (TAG), glycogen or glucose, although fecundity was diminished. However, one week of HFD resulted in decreased body mass and elevated TAG levels in mated flies. Finally, we investigated the role of AKH in regulating effects of HFD during aging. Both with normal diet (ND) and HFD, Akh mutant flies displayed increased longevity compared to control flies. However, both mutants and controls showed shortened lifespan on HFD compared to ND. In flies exposed to ND, fecundity is decreased in Akh mutants compared to controls after one week, but increased after three weeks. However, HFD leads to a similar decrease in fecundity in both genotypes after both exposure times. Thus, long-term exposure to HFD increases AKH signaling, impairs lifespan and fecundity and augments age-related behavioral senescence.
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Affiliation(s)
- Sifang Liao
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Mirjam Amcoff
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Dick R Nässel
- Department of Zoology, Stockholm University, Stockholm, Sweden.
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45
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Brown EB, Shah KD, Palermo J, Dey M, Dahanukar A, Keene AC. Ir56d-dependent fatty acid responses in Drosophila uncover taste discrimination between different classes of fatty acids. eLife 2021; 10:67878. [PMID: 33949306 PMCID: PMC8169106 DOI: 10.7554/elife.67878] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/04/2021] [Indexed: 11/24/2022] Open
Abstract
Chemosensory systems are critical for evaluating the caloric value and potential toxicity of food. While animals can discriminate between thousands of odors, much less is known about the discriminative capabilities of taste systems. Fats and sugars represent calorically potent and attractive food sources that contribute to hedonic feeding. Despite the differences in nutritional value between fats and sugars, the ability of the taste system to discriminate between different rewarding tastants is thought to be limited. In Drosophila, taste neurons expressing the ionotropic receptor 56d (IR56d) are required for reflexive behavioral responses to the medium-chain fatty acid, hexanoic acid. Here, we tested whether flies can discriminate between different classes of fatty acids using an aversive memory assay. Our results indicate that flies are able to discriminate medium-chain fatty acids from both short- and long-chain fatty acids, but not from other medium-chain fatty acids. While IR56d neurons are broadly responsive to short-, medium-, and long-chain fatty acids, genetic deletion of IR56d selectively disrupts response to medium-chain fatty acids. Further, IR56d+ GR64f+ neurons are necessary for proboscis extension response (PER) to medium-chain fatty acids, but both IR56d and GR64f neurons are dispensable for PER to short- and long-chain fatty acids, indicating the involvement of one or more other classes of neurons. Together, these findings reveal that IR56d is selectively required for medium-chain fatty acid taste, and discrimination of fatty acids occurs through differential receptor activation in shared populations of neurons. Our study uncovers a capacity for the taste system to encode tastant identity within a taste category.
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Affiliation(s)
- Elizabeth B Brown
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
| | - Kreesha D Shah
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States.,Wilkes Honors College, Florida Atlantic University, Jupiter, United States
| | - Justin Palermo
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
| | - Manali Dey
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, United States
| | - Anupama Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, United States.,Department of Molecular, Cell & Systems Biology, University of California, Riverside, Riverside, United States
| | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, United States
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46
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Bestea L, Réjaud A, Sandoz JC, Carcaud J, Giurfa M, de Brito Sanchez MG. Peripheral taste detection in honey bees: What do taste receptors respond to? Eur J Neurosci 2021; 54:4417-4444. [PMID: 33934411 DOI: 10.1111/ejn.15265] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 11/30/2022]
Abstract
Understanding the neural principles governing taste perception in species that bear economic importance or serve as research models for other sensory modalities constitutes a strategic goal. Such is the case of the honey bee (Apis mellifera), which is environmentally and socioeconomically important, given its crucial role as pollinator agent in agricultural landscapes and which has served as a traditional model for visual and olfactory neurosciences and for research on communication, navigation, and learning and memory. Here we review the current knowledge on honey bee gustatory receptors to provide an integrative view of peripheral taste detection in this insect, highlighting specificities and commonalities with other insect species. We describe behavioral and electrophysiological responses to several tastant categories and relate these responses, whenever possible, to known molecular receptor mechanisms. Overall, we adopted an evolutionary and comparative perspective to understand the neural principles of honey bee taste and define key questions that should be answered in future gustatory research centered on this insect.
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Affiliation(s)
- Louise Bestea
- Research Centre on Animal Cognition, Center for Integrative Biology, CNRS (UMR 5169), University of Toulouse, Toulouse, France
| | - Alexandre Réjaud
- Laboratoire Evolution et Diversité Biologique, CNRS, IRD (UMR 5174), University of Toulouse, Toulouse, France
| | - Jean-Christophe Sandoz
- Evolution, Genomes, Behavior and Ecology, CNRS, IRD (UMR 9191, University Paris Saclay, Gif-sur-Yvette, France
| | - Julie Carcaud
- Evolution, Genomes, Behavior and Ecology, CNRS, IRD (UMR 9191, University Paris Saclay, Gif-sur-Yvette, France
| | - Martin Giurfa
- Research Centre on Animal Cognition, Center for Integrative Biology, CNRS (UMR 5169), University of Toulouse, Toulouse, France.,College of Animal Sciences (College of Bee Science), Fujian Agriculture and Forestry University, Fuzhou, China.,Institut Universitaire de France (IUF), Paris, France
| | - Maria Gabriela de Brito Sanchez
- Research Centre on Animal Cognition, Center for Integrative Biology, CNRS (UMR 5169), University of Toulouse, Toulouse, France
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47
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Ni L. The Structure and Function of Ionotropic Receptors in Drosophila. Front Mol Neurosci 2021; 13:638839. [PMID: 33597847 PMCID: PMC7882480 DOI: 10.3389/fnmol.2020.638839] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 12/28/2020] [Indexed: 12/21/2022] Open
Abstract
Ionotropic receptors (IRs) are a highly divergent subfamily of ionotropic glutamate receptors (iGluR) and are conserved across Protostomia, a major branch of the animal kingdom that encompasses both Ecdysozoa and Lophothrochozoa. They are broadly expressed in peripheral sensory systems, concentrated in sensory dendrites, and function in chemosensation, thermosensation, and hygrosensation. As iGluRs, four IR subunits form a functional ion channel to detect environmental stimuli. Most IR receptors comprise individual stimulus-specific tuning receptors and one or two broadly expressed coreceptors. This review summarizes the discoveries of the structure of IR complexes and the expression and function of each IR, as well as discusses the future direction for IR studies.
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Affiliation(s)
- Lina Ni
- School of Neuroscience, Virginia Tech, Blacksburg, VA, United States
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48
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Ferreira EA, Lambert S, Verrier T, Marion-Poll F, Yassin A. Soft Selective Sweep on Chemosensory Genes Correlates with Ancestral Preference for Toxic Noni in a Specialist Drosophila Population. Genes (Basel) 2020; 12:genes12010032. [PMID: 33383708 PMCID: PMC7824377 DOI: 10.3390/genes12010032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/17/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022] Open
Abstract
Understanding how organisms adapt to environmental changes is a major question in evolution and ecology. In particular, the role of ancestral variation in rapid adaptation remains unclear because its trace on genetic variation, known as soft selective sweep, is often hardly recognizable from genome-wide selection scans. Here, we investigate the evolution of chemosensory genes in Drosophila yakuba mayottensis, a specialist subspecies on toxic noni (Morinda citrifolia) fruits on the island of Mayotte. We combine population genomics analyses and behavioral assays to evaluate the level of divergence in chemosensory genes and perception of noni chemicals between specialist and generalist subspecies of D. yakuba. We identify a signal of soft selective sweep on a handful of genes, with the most diverging ones involving a cluster of gustatory receptors expressed in bitter-sensing neurons. Our results highlight the potential role of ancestral genetic variation in promoting host plant specialization in herbivorous insects and identify a number of candidate genes underlying behavioral adaptation.
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Affiliation(s)
- Erina A. Ferreira
- Laboratoire Évolution, Génomes, Comportement et Écologie, CNRS, IRD, Université Paris-Saclay, 91198 Gif-sur-Yvette, France; (E.A.F.); (F.M.-P.)
- Institut Systématique Evolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique, MNHN, Sorbonne Université, EPHE 57 rue Cuvier, CP 50, 75005 Paris, France; (S.L.); (T.V.)
| | - Sophia Lambert
- Institut Systématique Evolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique, MNHN, Sorbonne Université, EPHE 57 rue Cuvier, CP 50, 75005 Paris, France; (S.L.); (T.V.)
| | - Thibault Verrier
- Institut Systématique Evolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique, MNHN, Sorbonne Université, EPHE 57 rue Cuvier, CP 50, 75005 Paris, France; (S.L.); (T.V.)
| | - Frédéric Marion-Poll
- Laboratoire Évolution, Génomes, Comportement et Écologie, CNRS, IRD, Université Paris-Saclay, 91198 Gif-sur-Yvette, France; (E.A.F.); (F.M.-P.)
- AgroParisTech, Université Paris-Saclay, 75231 Paris, France
| | - Amir Yassin
- Laboratoire Évolution, Génomes, Comportement et Écologie, CNRS, IRD, Université Paris-Saclay, 91198 Gif-sur-Yvette, France; (E.A.F.); (F.M.-P.)
- Institut Systématique Evolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique, MNHN, Sorbonne Université, EPHE 57 rue Cuvier, CP 50, 75005 Paris, France; (S.L.); (T.V.)
- Correspondence:
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49
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Vaziri A, Khabiri M, Genaw BT, May CE, Freddolino PL, Dus M. Persistent epigenetic reprogramming of sweet taste by diet. SCIENCE ADVANCES 2020; 6:6/46/eabc8492. [PMID: 33177090 PMCID: PMC7673743 DOI: 10.1126/sciadv.abc8492] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/23/2020] [Indexed: 05/25/2023]
Abstract
Diets rich in sugar, salt, and fat alter taste perception and food preference, contributing to obesity and metabolic disorders, but the molecular mechanisms through which this occurs are unknown. Here, we show that in response to a high sugar diet, the epigenetic regulator Polycomb Repressive Complex 2.1 (PRC2.1) persistently reprograms the sensory neurons of Drosophila melanogaster flies to reduce sweet sensation and promote obesity. In animals fed high sugar, the binding of PRC2.1 to the chromatin of the sweet gustatory neurons is redistributed to repress a developmental transcriptional network that modulates the responsiveness of these cells to sweet stimuli, reducing sweet sensation. Half of these transcriptional changes persist despite returning the animals to a control diet, causing a permanent decrease in sweet taste. Our results uncover a new epigenetic mechanism that, in response to the dietary environment, regulates neural plasticity and feeding behavior to promote obesity.
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Affiliation(s)
- Anoumid Vaziri
- The Molecular, Cellular and Developmental Biology Graduate Program, The University of Michigan, Ann Arbor, MI 49109, USA
- Department of Molecular, Cellular and Developmental Biology, College of Literature, Science, and the Arts, The University of Michigan, Ann Arbor, MI 49109, USA
| | - Morteza Khabiri
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Brendan T Genaw
- Program in Biology, College of Literature, Science, and the Arts, The University of Michigan, Ann Arbor, MI, 48109, USA
| | - Christina E May
- Department of Molecular, Cellular and Developmental Biology, College of Literature, Science, and the Arts, The University of Michigan, Ann Arbor, MI 49109, USA
- The Neuroscience Graduate Program, The University of Michigan, Ann Arbor, MI 49109, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Monica Dus
- The Molecular, Cellular and Developmental Biology Graduate Program, The University of Michigan, Ann Arbor, MI 49109, USA.
- Department of Molecular, Cellular and Developmental Biology, College of Literature, Science, and the Arts, The University of Michigan, Ann Arbor, MI 49109, USA
- Program in Biology, College of Literature, Science, and the Arts, The University of Michigan, Ann Arbor, MI, 48109, USA
- The Neuroscience Graduate Program, The University of Michigan, Ann Arbor, MI 49109, USA
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50
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Abstract
Insects thrive in diverse ecological niches in large part because of their highly sophisticated olfactory systems. Over the last two decades, a major focus in the study of insect olfaction has been on the role of olfactory receptors in mediating neuronal responses to environmental chemicals. In vivo, these receptors operate in specialized structures, called sensilla, which comprise neurons and non-neuronal support cells, extracellular lymph fluid and a precisely shaped cuticle. While sensilla are inherent to odour sensing in insects, we are only just beginning to understand their construction and function. Here, we review recent work that illuminates how odour-evoked neuronal activity is impacted by sensillar morphology, lymph fluid biochemistry, accessory signalling molecules in neurons and the physiological crosstalk between sensillar cells. These advances reveal multi-layered molecular and cellular mechanisms that determine the selectivity, sensitivity and dynamic modulation of odour-evoked responses in insects.
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Affiliation(s)
- Hayden R Schmidt
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015, Lausanne, Switzerland
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