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Alciatore G, Peguero DA, Gold M, Zurbrügg C, Niu M, Bargetze F, Mathys A. Preservation of agri-food byproducts by acidification and fermentation in black soldier fly larvae bioconversion. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 186:109-118. [PMID: 38875912 DOI: 10.1016/j.wasman.2024.05.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/05/2024] [Accepted: 05/25/2024] [Indexed: 06/16/2024]
Abstract
Maintaining a consistent supply of feedstock for efficient bioconversion of black soldier fly larvae (BSFL) presents challenges due to the fluctuating availability of biowastes and agri-food products. To address the challenge of consistent feedstock supply for BSFL, this study investigated the influence of three preservation methods: wild fermentation, inoculated fermentation, and acidification on agri-food by-products applied over three storage durations (1, 7, and 14 days), evaluating their impact on BSFL bioconversion, and feedstock nutrient and microbiota composition. The preserved feedstocks were characterized for gross nutrient, sugar, fermentation metabolite, and bacterial community analyses. All feedstock preservation methods and storage durations had a high bioconversion rate (21-25 % dry mass) and wet larval mass (170-196 mg). Notably, 7-and-14-day acidified feedstock had a significantly higher bioconversion rate compared to fermented feedstock. Acidification preserved feedstock nutrients best with only a 10 % difference compared to initial nutrient values. Fermentation produced typical lactic acid fermentation metabolites with reducing sugar contents; however, adding a lactic acid bacterial inoculum (7 log10 CFU kg feedstock-1) had no benefit, presumably due to the high nutrient content and existing richness in lactic acid bacteria. Preservations had little influence on Enterobacteriaceae (6.2-7.5 log10 CFU g-1) in freshly harvested larvae. Future research should assess the acidification and fermentation of different BSFL feedstocks and investigate the roles of feedstock pH, organic acids, and fermentation metabolites in more detail. Therefore, this study advances toward reliable and efficient insect-based nutrient recovery from agri-food by-products within the food system.
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Affiliation(s)
- Giacomo Alciatore
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, 8092 Zurich, Switzerland; Eawag: Swiss Federal Institute of Aquatic Science and Technology, Sandec: Department Sanitation, Water and Solid Water for Development, Überlandstrasse 133, 8600 Dübendorf, Switzerland
| | - Daniela A Peguero
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, 8092 Zurich, Switzerland; Eawag: Swiss Federal Institute of Aquatic Science and Technology, Sandec: Department Sanitation, Water and Solid Water for Development, Überlandstrasse 133, 8600 Dübendorf, Switzerland
| | - Moritz Gold
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, 8092 Zurich, Switzerland.
| | - Christian Zurbrügg
- Eawag: Swiss Federal Institute of Aquatic Science and Technology, Sandec: Department Sanitation, Water and Solid Water for Development, Überlandstrasse 133, 8600 Dübendorf, Switzerland
| | - Mutian Niu
- ETH Zurich, Institute of Agricultural Sciences, Animal Nutrition, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Franco Bargetze
- REPLOID Schweiz AG, Lerchenfeldstrasse 3, 9014 St. Gallen, Switzerland
| | - Alexander Mathys
- ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, 8092 Zurich, Switzerland
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2
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Guillemin J, Li J, Li V, McDowell SAT, Audette K, Davis G, Jelen M, Slamani S, Kelliher L, Gordon MD, Stanley M. Taste cells expressing Ionotropic Receptor 94e reciprocally impact feeding and egg laying in Drosophila. Cell Rep 2024; 43:114625. [PMID: 39141516 DOI: 10.1016/j.celrep.2024.114625] [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: 02/02/2024] [Revised: 06/01/2024] [Accepted: 07/30/2024] [Indexed: 08/16/2024] Open
Abstract
Chemosensory cells across the body of Drosophila melanogaster evaluate the environment to prioritize certain behaviors. Previous mapping of gustatory receptor neurons (GRNs) on the fly labellum identified a set of neurons in L-type sensilla that express Ionotropic Receptor 94e (IR94e), but the impact of IR94e GRNs on behavior remains unclear. We used optogenetics and chemogenetics to activate IR94e neurons and found that they drive mild feeding suppression but enhance egg laying. In vivo calcium imaging revealed that IR94e GRNs respond strongly to certain amino acids, including glutamate, and that IR94e plus co-receptors IR25a and IR76b are required for amino acid detection. Furthermore, IR94e mutants show behavioral changes to solutions containing amino acids, including increased consumption and decreased egg laying. Overall, our results suggest that IR94e GRNs on the fly labellum discourage feeding and encourage egg laying as part of an important behavioral switch in response to certain chemical cues.
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Affiliation(s)
| | - Jinfang Li
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Viktoriya Li
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Sasha A T McDowell
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Kayla Audette
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Grace Davis
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Meghan Jelen
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Samy Slamani
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Liam Kelliher
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Michael D Gordon
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
| | - Molly Stanley
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA.
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3
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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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4
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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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5
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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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6
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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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7
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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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8
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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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9
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Jouandet GC, Alpert MH, Simões JM, Suhendra R, Frank DD, Levy JI, Para A, Kath WL, Gallio M. Rapid threat assessment in the Drosophila thermosensory system. Nat Commun 2023; 14:7067. [PMID: 37923719 PMCID: PMC10624821 DOI: 10.1038/s41467-023-42864-5] [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: 04/19/2023] [Accepted: 10/23/2023] [Indexed: 11/06/2023] Open
Abstract
Neurons that participate in sensory processing often display "ON" responses, i.e., fire transiently at the onset of a stimulus. ON transients are widespread, perhaps universal to sensory coding, yet their function is not always well-understood. Here, we show that ON responses in the Drosophila thermosensory system extrapolate the trajectory of temperature change, priming escape behavior if unsafe thermal conditions are imminent. First, we show that second-order thermosensory projection neurons (TPN-IIIs) and their Lateral Horn targets (TLHONs), display ON responses to thermal stimuli, independent of direction of change (heating or cooling) and of absolute temperature. Instead, they track the rate of temperature change, with TLHONs firing exclusively to rapid changes (>0.2 °C/s). Next, we use connectomics to track TLHONs' output to descending neurons that control walking and escape, and modeling and genetic silencing to demonstrate how ON transients can flexibly amplify aversive responses to small thermal change. Our results suggest that, across sensory systems, ON transients may represent a general mechanism to systematically anticipate and respond to salient or dangerous conditions.
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Affiliation(s)
| | - Michael H Alpert
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
| | | | - Richard Suhendra
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL, USA
| | - Dominic D Frank
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- Laboratory of Social Evolution and Behavior, The Rockefeller University, New York, NY, USA
| | - Joshua I Levy
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Alessia Para
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
| | - William L Kath
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL, USA
- National Institute for Theory and Mathematics in Biology, Northwestern University, Chicago, IL, USA
| | - Marco Gallio
- Department of Neurobiology, Northwestern University, Evanston, IL, USA.
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10
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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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11
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Jelen M, Musso PY, Junca P, Gordon MD. Optogenetic induction of appetitive and aversive taste memories in Drosophila. eLife 2023; 12:e81535. [PMID: 37750673 PMCID: PMC10561975 DOI: 10.7554/elife.81535] [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: 07/04/2022] [Accepted: 09/22/2023] [Indexed: 09/27/2023] Open
Abstract
Tastes typically evoke innate behavioral responses that can be broadly categorized as acceptance or rejection. However, research in Drosophila melanogaster indicates that taste responses also exhibit plasticity through experience-dependent changes in mushroom body circuits. In this study, we develop a novel taste learning paradigm using closed-loop optogenetics. We find that appetitive and aversive taste memories can be formed by pairing gustatory stimuli with optogenetic activation of sensory neurons or dopaminergic neurons encoding reward or punishment. As with olfactory memories, distinct dopaminergic subpopulations drive the parallel formation of short- and long-term appetitive memories. Long-term memories are protein synthesis-dependent and have energetic requirements that are satisfied by a variety of caloric food sources or by direct stimulation of MB-MP1 dopaminergic neurons. Our paradigm affords new opportunities to probe plasticity mechanisms within the taste system and understand the extent to which taste responses depend on experience.
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Affiliation(s)
- Meghan Jelen
- Department of Zoology and Life Sciences Institute, University of British ColumbiaVancouverCanada
| | - Pierre-Yves Musso
- Department of Zoology and Life Sciences Institute, University of British ColumbiaVancouverCanada
| | - Pierre Junca
- Department of Zoology and Life Sciences Institute, University of British ColumbiaVancouverCanada
| | - Michael D Gordon
- Department of Zoology and Life Sciences Institute, University of British ColumbiaVancouverCanada
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12
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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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13
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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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14
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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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15
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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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16
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Yamase Y, Huang H, Mitoh Y, Egusa M, Miyawaki T, Yoshida R. Taste Responses and Ingestive Behaviors to Ingredients of Fermented Milk in Mice. Foods 2023; 12:1150. [PMID: 36981077 PMCID: PMC10048529 DOI: 10.3390/foods12061150] [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: 11/24/2022] [Revised: 01/13/2023] [Accepted: 03/02/2023] [Indexed: 03/11/2023] Open
Abstract
Fermented milk is consumed worldwide because of its nutritious and healthful qualities. Although it is somewhat sour, causing some to dislike it, few studies have examined taste aspects of its ingredients. Wild-type mice and T1R3-GFP-KO mice lacking sweet/umami receptors were tested with various taste components (sucrose, galactose, lactose, galacto-oligosaccharides, fructo-oligosaccharides, l- and d-lactic acid) using 48 h two-bottle tests and short-term lick tests. d-lactic acid levels were measured after the ingestion of d- or; l-lactic acid or water to evaluate d-lactic acidosis. In wild-type mice, for the sweet ingredients the number of licks increased in a concentration-dependent manner, but avoidance was observed at higher concentrations in 48 h two-bottle tests; the sour ingredients d- and l-lactic acid showed concentration-dependent decreases in preference in both short- and long-term tests. In 48 h two-bottle tests comparing d- and l-lactic acid, wild-type but not T1R3-GFP-KO mice showed higher drinking rates for l-lactic acid. d-lactic acidosis did not occur and thus did not contribute to this preference. These results suggest that intake in short-term lick tests varied by preference for each ingredient, whereas intake variation in long-term lick tests reflects postingestive effects. l-lactic acid may have some palatable taste in addition to sour taste.
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Affiliation(s)
- Yuko Yamase
- Department of Dental Anesthesiology and Special Care Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
| | - Hai Huang
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
| | - Yoshihiro Mitoh
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan
| | - Masahiko Egusa
- Department of Dental Anesthesiology and Special Care Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
| | - Takuya Miyawaki
- Department of Dental Anesthesiology and Special Care Dentistry, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
| | - Ryusuke Yoshida
- Department of Oral Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
- Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan
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17
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King BH, Gunathunga PB. Gustation in insects: taste qualities and types of evidence used to show taste function of specific body parts. JOURNAL OF INSECT SCIENCE (ONLINE) 2023; 23:11. [PMID: 37014302 PMCID: PMC10072106 DOI: 10.1093/jisesa/iead018] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/03/2023] [Accepted: 03/10/2023] [Indexed: 06/19/2023]
Abstract
The insect equivalent of taste buds are gustatory sensilla, which have been found on mouthparts, pharynxes, antennae, legs, wings, and ovipositors. Most gustatory sensilla are uniporous, but not all apparently uniporous sensilla are gustatory. Among sensilla containing more than one neuron, a tubular body on one dendrite is also indicative of a taste sensillum, with the tubular body adding tactile function. But not all taste sensilla are also tactile. Additional morphological criteria are often used to recognize if a sensillum is gustatory. Further confirmation of such criteria by electrophysiological or behavioral evidence is needed. The five canonical taste qualities to which insects respond are sweet, bitter, sour, salty, and umami. But not all tastants that insects respond to easily fit in these taste qualities. Categories of insect tastants can be based not only on human taste perception, but also on whether the response is deterrent or appetitive and on chemical structure. Other compounds that at least some insects taste include, but are not limited to: water, fatty acids, metals, carbonation, RNA, ATP, pungent tastes as in horseradish, bacterial lipopolysaccharides, and contact pheromones. We propose that, for insects, taste be defined not only as a response to nonvolatiles but also be restricted to responses that are, or are thought to be, mediated by a sensillum. This restriction is useful because some of the receptor proteins in gustatory sensilla are also found elsewhere.
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Affiliation(s)
- B H King
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA
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18
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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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19
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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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20
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Abstract
Salt taste, the taste of sodium chloride (NaCl), is mechanistically one of the most complex and puzzling among basic tastes. Sodium has essential functions in the body but causes harm in excess. Thus, animals use salt taste to ingest the right amount of salt, which fluctuates by physiological needs: typically, attraction to low salt concentrations and rejection of high salt. This concentration-valence relationship is universally observed in terrestrial animals, and research has revealed complex peripheral codes for NaCl involving multiple taste pathways of opposing valence. Sodium-dependent and -independent pathways mediate attraction and aversion to NaCl, respectively. Gustatory sensors and cells that transduce NaCl have been uncovered, along with downstream signal transduction and neurotransmission mechanisms. However, much remains unknown. This article reviews classical and recent advances in our understanding of the molecular and cellular mechanisms underlying salt taste in mammals and insects and discusses perspectives on human salt taste.
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Affiliation(s)
- Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan; .,Japan Science and Technology Agency, CREST, Saitama, Japan
| | - Michael D Gordon
- Department of Zoology and Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
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21
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Plasticity in Chemical Host Plant Recognition in Herbivorous Insects and Its Implication for Pest Control. BIOLOGY 2022; 11:biology11121842. [PMID: 36552352 PMCID: PMC9775997 DOI: 10.3390/biology11121842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022]
Abstract
Chemical communication is very important in herbivorous insects, with many species being important agricultural pests. They often use olfactory cues to find their host plants at a distance and evaluate their suitability upon contact with non-volatile cues. Responses to such cues are modulated through interactions between various stimuli of biotic and abiotic origin. In addition, the response to the same stimulus can vary as a function of, for example, previous experience, age, mating state, sex, and morph. Here we summarize recent advances in the understanding of plant localization and recognition in herbivorous insects with a focus on the interplay between long- and short-range signals in a complex environment. We then describe recent findings illustrating different types of plasticity in insect plant choice behavior and the underlying neuronal mechanisms at different levels of the chemosensory pathway. In the context of strong efforts to replace synthetic insecticides with alternative pest control methods, understanding combined effects between long- and close-range chemical cues in herbivore-plant interactions and their complex environment in host choice are crucial to develop effective plant protection methods. Furthermore, plasticity of behavioral and neuronal responses to chemical cues needs to be taken into account to develop effective sustainable pest insect control through behavioral manipulation.
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22
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Mahadevan VP, Lavista-Llanos S, Knaden M, Hansson BS. No functional contribution of the gustatory receptor, Gr64b, co-expressed in olfactory sensory neurons of Drosophila melanogaster. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.980351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chemosensation is essential for the survival of insects. Activities like searching for food, mating, and oviposition in the fruit fly, Drosophila melanogaster are to a great extent governed by chemical cues detected via olfaction and gustation. This chemical information is conveyed to higher brain centers via populations of diverse olfactory sensory neurons (OSNs) and gustatory sensory neurons (GSNs) expressing olfactory receptors (ORs) and gustatory receptors (GRs), respectively. ORs are exclusively expressed in the antenna and in the maxillary palps, while GRs are widely expressed in the labellum, tarsi, genitalia etc. Interestingly, 14 GRs were previously reported to be expressed in the antenna of D. melanogaster. However, the spatial expression pattern for all GRs and their functional role are still unclear. Recent data challenge the dogma that single OSNs express a single OR. In the present study, we studied the expression of 12 previously reported GRs among sensory structures on the fly antenna using the Gal4-UAS binary expression system. We observed antennal expression of nine out of the 12 reported. Out of these nine, consistent expression was only apparent for Gr64b, and we reconfirmed its presence in OSNs innervating three glomeruli in the antennal lobe. These glomeruli are known to be innervated by ab5A, ab5B and ab8A OSNs, respectively. Next, we generated double labeling crosses with Gr64b and observed co-expression of Gr64b with Or47a, which is expressed in the ab5B neuron. To elucidate the functional role of Gr64b co-expressed with Or47a, we challenged Or47a-expressing OSNs in wild type and Gr64b–/– mutant flies with odor stimulation using the single sensillum recording technique in two satiation states (fed and starved). Notably, we did not observe any significant odor sensitivity or specificity changes in Gr64b mutants as compared to wild type flies. Taken together, our results reveal co-expression of GRs with ORs in olfactory sensory neurons, while the functional contribution of the GR in this context remains obscure.
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23
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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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24
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Xiao S, Baik LS, Shang X, Carlson JR. Meeting a threat of the Anthropocene: Taste avoidance of metal ions by Drosophila. Proc Natl Acad Sci U S A 2022; 119:e2204238119. [PMID: 35700364 PMCID: PMC9231609 DOI: 10.1073/pnas.2204238119] [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: 03/09/2022] [Accepted: 05/06/2022] [Indexed: 11/18/2022] Open
Abstract
The Anthropocene Epoch poses a critical challenge for organisms: they must cope with new threats at a rapid rate. These threats include toxic chemical compounds released into the environment by human activities. Here, we examine elevated concentrations of heavy metal ions as an example of anthropogenic stressors. We find that the fruit fly Drosophila avoids nine metal ions when present at elevated concentrations that the flies experienced rarely, if ever, until the Anthropocene. We characterize the avoidance of feeding and egg laying on metal ions, and we identify receptors, neurons, and taste organs that contribute to this avoidance. Different subsets of taste receptors, including members of both Ir (Ionotropic receptor) and Gr (Gustatory receptor) families contribute to the avoidance of different metal ions. We find that metal ions activate certain bitter-sensing neurons and inhibit sugar-sensing neurons. Some behavioral responses are mediated largely through neurons of the pharynx. Feeding avoidance remains stable over 10 generations of exposure to copper and zinc ions. Some responses to metal ions are conserved across diverse dipteran species, including the mosquito Aedes albopictus. Our results suggest mechanisms that may be essential to insects as they face challenges from environmental changes in the Anthropocene.
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Affiliation(s)
- Shuke Xiao
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
| | - Lisa S. Baik
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
| | - Xueying Shang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
| | - John R. Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
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25
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Khan M, Hartmann AH, O’Donnell MP, Piccione M, Pandey A, Chao PH, Dwyer ND, Bargmann CI, Sengupta P. Context-dependent reversal of odorant preference is driven by inversion of the response in a single sensory neuron type. PLoS Biol 2022; 20:e3001677. [PMID: 35696430 PMCID: PMC9232122 DOI: 10.1371/journal.pbio.3001677] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 06/24/2022] [Accepted: 05/16/2022] [Indexed: 11/18/2022] Open
Abstract
The valence and salience of individual odorants are modulated by an animal’s innate preferences, learned associations, and internal state, as well as by the context of odorant presentation. The mechanisms underlying context-dependent flexibility in odor valence are not fully understood. Here, we show that the behavioral response of Caenorhabditis elegans to bacterially produced medium-chain alcohols switches from attraction to avoidance when presented in the background of a subset of additional attractive chemicals. This context-dependent reversal of odorant preference is driven by cell-autonomous inversion of the response to these alcohols in the single AWC olfactory neuron pair. We find that while medium-chain alcohols inhibit the AWC olfactory neurons to drive attraction, these alcohols instead activate AWC to promote avoidance when presented in the background of a second AWC-sensed odorant. We show that these opposing responses are driven via engagement of distinct odorant-directed signal transduction pathways within AWC. Our results indicate that context-dependent recruitment of alternative intracellular signaling pathways within a single sensory neuron type conveys opposite hedonic valences, thereby providing a robust mechanism for odorant encoding and discrimination at the periphery.
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Affiliation(s)
- Munzareen Khan
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Anna H. Hartmann
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Michael P. O’Donnell
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Madeline Piccione
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Anjali Pandey
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Pin-Hao Chao
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
| | - Noelle D. Dwyer
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | | | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, Massachusetts, United States of America
- * E-mail:
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26
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Requirement for an Otopetrin-like protein for acid taste in Drosophila. Proc Natl Acad Sci U S A 2021; 118:2110641118. [PMID: 34911758 PMCID: PMC8713817 DOI: 10.1073/pnas.2110641118] [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] [Accepted: 11/01/2021] [Indexed: 11/18/2022] Open
Abstract
Receptors for bitter, sugar, and other tastes have been identified in the fruit fly Drosophila melanogaster, while a broadly tuned receptor for the taste of acid has been elusive. Previous work showed that such a receptor was unlikely to be encoded by a gene within one of the two major families of taste receptors in Drosophila, the "gustatory receptors" and "ionotropic receptors." Here, to identify the acid taste receptor, we tested the contributions of genes encoding proteins distantly related to the mammalian Otopertrin1 (OTOP1) proton channel that functions as a sour receptor in mice. RNA interference (RNAi) knockdown or mutation by CRISPR/Cas9 of one of the genes, Otopetrin-Like A (OtopLA), but not of the others (OtopLB or OtopLC) severely impaired the behavioral rejection to a sweet solution laced with high levels of HCl or carboxylic acids and greatly reduced acid-induced action potentials measured from taste hairs. An isoform of OtopLA that we isolated from the proboscis was sufficient to restore behavioral sensitivity and acid-induced action potential firing in OtopLA mutant flies. At lower concentrations, HCl was attractive to the flies, and this attraction was abolished in the OtopLA mutant. Cell type-specific rescue experiments showed that OtopLA functions in distinct subsets of gustatory receptor neurons for repulsion and attraction to high and low levels of protons, respectively. This work highlights a functional conservation of a sensory receptor in flies and mammals and shows that the same receptor can function in both appetitive and repulsive behaviors.
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27
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Devineni AV, Deere JU, Sun B, Axel R. Individual bitter-sensing neurons in Drosophila exhibit both ON and OFF responses that influence synaptic plasticity. Curr Biol 2021; 31:5533-5546.e7. [PMID: 34731675 DOI: 10.1016/j.cub.2021.10.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 09/04/2021] [Accepted: 10/08/2021] [Indexed: 01/07/2023]
Abstract
The brain generates internal representations that translate sensory stimuli into appropriate behavior. In the taste system, different tastes activate distinct populations of sensory neurons. We investigated the temporal properties of taste responses in Drosophila and discovered that different types of taste sensory neurons show striking differences in their response dynamics. Strong responses to stimulus onset (ON responses) and offset (OFF responses) were observed in bitter-sensing neurons in the labellum, whereas bitter neurons in the leg and other classes of labellar taste neurons showed only an ON response. Individual labellar bitter neurons generate both ON and OFF responses through a cell-intrinsic mechanism that requires canonical bitter receptors. A single receptor complex likely generates both ON and OFF responses to a given bitter ligand. These ON and OFF responses in the periphery are propagated to dopaminergic neurons that mediate aversive learning, and the presence of the OFF response impacts synaptic plasticity when bitter is used as a reinforcement cue. These studies reveal previously unknown features of taste responses that impact neural circuit function and may be important for behavior. Moreover, these studies show that OFF responses can dramatically influence timing-based synaptic plasticity, which is thought to underlie associative learning.
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Affiliation(s)
- Anita V Devineni
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA.
| | - Julia U Deere
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA
| | - Bei Sun
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA
| | - Richard Axel
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
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