1
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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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2
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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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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. 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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4
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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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5
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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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6
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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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7
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Brown E, Worden K, Li Y, Masek P, Keene AC. Innate and Conditioned Taste Processing in Drosophila. Cold Spring Harb Protoc 2023; 2023:pdb.top107864. [PMID: 36787965 PMCID: PMC10750968 DOI: 10.1101/pdb.top107864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Peripheral detection of tastants allows animals to detect the dietary value of food and its potential toxicity. Many tastants such as sugars and fats elicit reflexive appetitive responses, whereas other foods such as quinine induce aversion. The relative value of food can change in accordance with an animal's internal state and prior experience. Understanding the neural and genetic bases for the detection and response to tastants, as well as how these behaviors change with experience, is central to sensory neuroscience. The presentation of attractive tastants to the proboscis or legs of the fruit fly Drosophila melanogaster induces a robust and reflexive proboscis-extension response (PER). This quantifiable response can be used to study the receptors underlying taste detection, the neural circuits involved in sensory processing, and the musculature required for a simple feeding behavior. Furthermore, we have developed a memory assay pairing appetitive and bitter tastants, resulting in aversive taste conditioning, in which the PER response to attractive tastants is diminished. Unlike many memory assays, this assay does not require specialized equipment and can be readily implemented in teaching and research laboratories. Here, we introduce protocols for studying the PER feeding response and aversive taste memory in Drosophila.
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Affiliation(s)
- Elizabeth Brown
- Department of Biology, Texas A&M University, College Station, Texas 77843, USA
| | - Kurtresha Worden
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Yuanyuan Li
- Department of Biological Sciences, Binghamton University, Binghamton, New York 13902, USA
| | - Pavel Masek
- Department of Biological Sciences, Binghamton University, Binghamton, New York 13902, USA
| | - Alex C Keene
- Department of Biology, Texas A&M University, College Station, Texas 77843, USA
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8
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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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9
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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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10
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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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11
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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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12
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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; 12:84856. [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] [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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13
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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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14
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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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15
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Copy number changes in co-expressed odorant receptor genes enable selection for sensory differences in drosophilid species. Nat Ecol Evol 2022; 6:1343-1353. [PMID: 35864227 DOI: 10.1038/s41559-022-01830-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 06/15/2022] [Indexed: 11/09/2022]
Abstract
Despite numerous examples of chemoreceptor gene family expansions and contractions, how these relate to modifications in the sensory neuron populations in which they are expressed remains unclear. Drosophila melanogaster's odorant receptor (Or) family is ideal for addressing this question because most Ors are expressed in distinct olfactory sensory neuron (OSN) types. Between-species changes in Or copy number may therefore indicate increases or reductions in the number of OSN populations. Here we investigated the Or67a subfamily, which exhibits copy number variation in D. melanogaster and its closest relatives: D. simulans, D. sechellia and D. mauritiana. These species' common ancestor had three Or67a paralogues that had already diverged adaptively. Following speciation, two Or67a paralogues were lost independently in D. melanogaster and D. sechellia, with ongoing positive selection shaping the intact genes. Unexpectedly, the functionally diverged Or67a paralogues in D. simulans are co-expressed in a single neuron population, which projects to a glomerulus homologous to that innervated by Or67a neurons in D. melanogaster. Thus, while sensory pathway neuroanatomy is conserved, independent selection on co-expressed receptors has contributed to species-specific peripheral coding. This work reveals a type of adaptive change largely overlooked for olfactory evolution, raising the possibility that similar processes influence other cases of insect Or co-expression.
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16
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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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17
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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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18
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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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19
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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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20
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Drum ZA, Lanno SM, Gregory SM, Shimshak SJ, Ahamed M, Barr W, Bekele B, Biester A, Castro C, Connolly L, DelGaudio N, Humphrey W, Karimi H, Karolczak S, Lawrence TS, McCracken A, Miller-Medzon N, Murphy L, Park C, Park S, Qiu C, Serra K, Snyder G, Strauss A, Tang S, Vyzas C, Coolon JD. Genomics analysis of hexanoic acid exposure in Drosophila species. G3-GENES GENOMES GENETICS 2021; 12:6402009. [PMID: 34718544 PMCID: PMC8727985 DOI: 10.1093/g3journal/jkab354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/10/2021] [Indexed: 12/04/2022]
Abstract
Drosophila sechellia is a dietary specialist endemic to the Seychelles islands that has evolved to consume the fruit of Morinda citrifolia. When ripe, the fruit of M. citrifolia contains octanoic acid and hexanoic acid, two medium-chain fatty acid volatiles that deter and are toxic to generalist insects. Drosophila sechellia has evolved resistance to these volatiles allowing it to feed almost exclusively on this host plant. The genetic basis of octanoic acid resistance has been the focus of multiple recent studies, but the mechanisms that govern hexanoic acid resistance in D. sechellia remain unknown. To understand how D. sechellia has evolved to specialize on M. citrifolia fruit and avoid the toxic effects of hexanoic acid, we exposed adult D. sechellia, D. melanogaster and D. simulans to hexanoic acid and performed RNA sequencing comparing their transcriptional responses to identify D. sechellia specific responses. Our analysis identified many more genes responding transcriptionally to hexanoic acid in the susceptible generalist species than in the specialist D. sechellia. Interrogation of the sets of differentially expressed genes showed that generalists regulated the expression of many genes involved in metabolism and detoxification whereas the specialist primarily downregulated genes involved in the innate immunity. Using these data, we have identified interesting candidate genes that may be critically important in aspects of adaptation to their food source that contains high concentrations of HA. Understanding how gene expression evolves during dietary specialization is crucial for our understanding of how ecological communities are built and how evolution shapes trophic interactions.
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Affiliation(s)
- Zachary A Drum
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Stephen M Lanno
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Sara M Gregory
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Serena J Shimshak
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Mukshud Ahamed
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Will Barr
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Bethlehem Bekele
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Alison Biester
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Colleen Castro
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Lauren Connolly
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Nicole DelGaudio
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - William Humphrey
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Helen Karimi
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Sophie Karolczak
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | | | - Andrew McCracken
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | | | - Leah Murphy
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Cameron Park
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Sojeong Park
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Chloe Qiu
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Kevin Serra
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Gigi Snyder
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Alexa Strauss
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Spencer Tang
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Christina Vyzas
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
| | - Joseph D Coolon
- Department of Biology, Wesleyan University,Middletown, CT 06457, USA
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21
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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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22
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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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23
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Aryal B, Lee Y. Histamine gustatory aversion in Drosophila melanogaster. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 134:103586. [PMID: 33992752 DOI: 10.1016/j.ibmb.2021.103586] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/30/2021] [Accepted: 05/01/2021] [Indexed: 06/12/2023]
Abstract
Many foods and drinks contain histamine; however, the mechanisms that drive histamine taste perception have not yet been investigated. Here, we use a simple model organism, Drosophila melanogaster, to dissect the molecular sensors required to taste histamine. We first investigated histidine and histamine taste perception by performing a binary food choice assay and electrophysiology to identify essential sensilla for histamine sensing in the labellum. Histamine was found to activate S-type sensilla, which harbor bitter-sensing gustatory receptor neurons. Moreover, unbiased genetic screening for chemoreceptors revealed that a gustatory receptor, GR22e and an ionotropic receptor, IR76b are required for histamine sensing. Ectopic expression of GR22e was sufficient to induce a response in I-type sensilla, which normally do not respond to histamine. Taken together, our findings provide new insights into the mechanisms by which insects discriminate between the toxic histamine and beneficial histidine via their taste receptors.
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Affiliation(s)
- Binod Aryal
- 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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24
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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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25
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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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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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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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Li R, Jiang GF, Shu XH, Wang YQ, Li MJ. Identification and Expression Profile Analysis of Chemosensory Genes From the Antennal Transcriptome of Bamboo Locust ( Ceracris kiangsu). Front Physiol 2020; 11:889. [PMID: 33013431 PMCID: PMC7509195 DOI: 10.3389/fphys.2020.00889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 06/30/2020] [Indexed: 11/29/2022] Open
Abstract
Studies of chemosensory genes are key to a better understanding of intra- and interspecific communications between insects and their environment and provide opportunities for developing environmentally friendly pesticides to target pest species. The bamboo locust Ceracris kiangsu Tsai (Orthoptera: Acrididae) is one of the most important bamboo leaf-eating insects in southern China. However, the genes underlying olfactory sensation are lacking in the bamboo locust. In this study, the transcriptomes of male and female C. kiangsu antennae were sequenced and analyzed. A total of 125 chemosensory genes, including 91 odorant receptors (ORs), 13 ionotropic receptors (IRs), 13 odorant-binding proteins (OBPs), six chemosensory proteins (CSPs), and two sensory neuron membrane proteins, were identified based on sequence alignment and phylogenetic analyses. The expression patterns of all candidate genes on the antennae of males and females, maxillary palps, tarsi, wings, and thoraxes-abdomens were confirmed by real-time quantitative PCR. The analyses demonstrated that most genes are highly expressed in the antennae, and 35 ORs, 7 IRs, 10 OBPs, and 1 CSP exhibit significantly male-biased expression patterns, indicating their potential functions in mating behavior and the recognition of female sex pheromones. In addition to the antennal-predominant genes, some were abundant in the maxillary palps and some in the non-olfactory tissues, suggesting their different functions in the olfactory system of C. kiangsu. Our research offers an extensive resource for investigating the chemoreception mechanism of C. kiangsu. Further studies of olfactory function will provide comprehensive methods and original strategies for integrated pest management.
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Affiliation(s)
- Ran Li
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Guo-Fang Jiang
- College of Oceanology and Food Science, Quanzhou Normal University, Quanzhou, China
| | - Xiao-Han Shu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yu-Qi Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Ming-Jie Li
- College of Oceanology and Food Science, Quanzhou Normal University, Quanzhou, China
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29
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Wu Z, Cui Y, Ma J, Qu M, Lin J. Analyses of chemosensory genes provide insight into the evolution of behavioral differences to phytochemicals in Bactrocera species. Mol Phylogenet Evol 2020; 151:106858. [DOI: 10.1016/j.ympev.2020.106858] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 05/15/2020] [Accepted: 05/21/2020] [Indexed: 02/07/2023]
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Yin NN, Nuo SM, Xiao HY, Zhao YJ, Zhu JY, Liu NY. The ionotropic receptor gene family in Lepidoptera and Trichoptera: Annotation, evolutionary and functional perspectives. Genomics 2020; 113:601-612. [PMID: 33002624 DOI: 10.1016/j.ygeno.2020.09.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/01/2020] [Accepted: 09/24/2020] [Indexed: 10/23/2022]
Abstract
Lepidoptera (moths and butterflies) and Trichoptera (caddisflies), belonging to the superorder Amphiesmenoptera, are the most diverse insect orders as representatives of the terrestrial and aquatic insects, respectively. The insects of the two orders possess different biological and behavioral characteristics, especially their larvae, presumably resulting in the differences of the ionotropic receptor (IR) genes in numbers, sequence characteristics or gene structure. Here, we employed genomics, transcriptomics, bioinformatics, phylogenetics and molecular biology strategies to characterize the IR gene repertoire in Lepidoptera and Trichoptera. Genome and transcriptome analyses with exhaustive homology-based searches and manual efforts, in 32 lepidopterans and five trichopterans, led to the identification of 1449 genes encoding IRs with 1170 full-length sequences, representing the most comprehensive set of chemoreceptor superfamilies across the Amphiesmenoptera. Analysis of gene gains and losses in orthologous groups implied that some IRs were lost in related species, and multiple gene copies occurred mainly in divergent IRs (D-IRs) by gene duplications. Phylogenetic analysis of 2442 IR proteins from 67 species revealed that Lepidoptera and Trichoptera IRs could be classified into three subfamilies, i.e., 14 antennal IRs (A-IRs), five Lepidoptera-specific IRs (LS-IRs) and four D-IRs. Of the three subfamilies, A-IRs and LS-IRs members within orthologous groups exhibited high conservation of gene structure, but D-IRs shared extremely low amino acid identities (below 30%). Expression profiles revealed functional diversities of IRs from Bombyx mori and Papilio xuthus involving smell, taste or reproduction, in which some genes displayed sex-biased expression in antennae associated with specific chemosensory behaviors of female or male adults. Our current study has provided insights into the evolution, conservation and divergence of IRs between/within Lepidoptera and Trichoptera, and allows for further experiments to investigate IR functions.
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Affiliation(s)
- Ning-Na Yin
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China
| | - Shu-Mei Nuo
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China
| | - Hai-Yan Xiao
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China
| | - Yu-Jie Zhao
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China
| | - Jia-Ying Zhu
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China
| | - Nai-Yong Liu
- Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China.
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Kozma MT, Ngo-Vu H, Rump MT, Bobkov YV, Ache BW, Derby CD. Single cell transcriptomes reveal expression patterns of chemoreceptor genes in olfactory sensory neurons of the Caribbean spiny lobster, Panulirus argus. BMC Genomics 2020; 21:649. [PMID: 32962631 PMCID: PMC7510291 DOI: 10.1186/s12864-020-07034-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/27/2020] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Crustaceans express several classes of receptor genes in their antennules, which house olfactory sensory neurons (OSNs) and non-olfactory chemosensory neurons. Transcriptomics studies reveal that candidate chemoreceptor proteins include variant Ionotropic Receptors (IRs) including both co-receptor IRs and tuning IRs, Transient Receptor Potential (TRP) channels, Gustatory Receptors, epithelial sodium channels, and class A G-protein coupled receptors (GPCRs). The Caribbean spiny lobster, Panulirus argus, expresses in its antennules nearly 600 IRs, 17 TRP channels, 1 Gustatory Receptor, 7 epithelial sodium channels, 81 GPCRs, 6 G proteins, and dozens of enzymes in signaling pathways. However, the specific combinatorial expression patterns of these proteins in single sensory neurons are not known for any crustacean, limiting our understanding of how their chemosensory systems encode chemical quality. RESULTS The goal of this study was to use transcriptomics to describe expression patterns of chemoreceptor genes in OSNs of P. argus. We generated and analyzed transcriptomes from 7 single OSNs, some of which were shown to respond to a food odor, as well as an additional 7 multicell transcriptomes from preparations containing few (2-4), several (ca. 15), or many (ca. 400) OSNs. We found that each OSN expressed the same 2 co-receptor IRs (IR25a, IR93a) but not the other 2 antennular coIRs (IR8a, IR76b), 9-53 tuning IRs but only one to a few in high abundance, the same 5 TRP channels plus up to 5 additional TRPs, 12-17 GPCRs including the same 5 expressed in every single cell transcriptome, the same 3 G proteins plus others, many enzymes in the signaling pathways, but no Gustatory Receptors or epithelial sodium channels. The greatest difference in receptor expression among the OSNs was the identity of the tuning IRs. CONCLUSIONS Our results provide an initial view of the combinatorial expression patterns of receptor molecules in single OSNs in one species of decapod crustacean, including receptors directly involved in olfactory transduction and others likely involved in modulation. Our results also suggest differences in receptor expression in OSNs vs. other chemosensory neurons.
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Affiliation(s)
- Mihika T Kozma
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Hanh Ngo-Vu
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Matthew T Rump
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA
| | - Yuriy V Bobkov
- Whitney Laboratory, University of Florida, St. Augustine, Florida, 32084, USA
| | - Barry W Ache
- Whitney Laboratory, University of Florida, St. Augustine, Florida, 32084, USA
| | - Charles D Derby
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA.
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Chen YCD, Dahanukar A. Recent advances in the genetic basis of taste detection in Drosophila. Cell Mol Life Sci 2020; 77:1087-1101. [PMID: 31598735 PMCID: PMC7125039 DOI: 10.1007/s00018-019-03320-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/10/2019] [Accepted: 09/23/2019] [Indexed: 01/05/2023]
Abstract
The insect gustatory system senses taste information from environmental food substrates and processes it to control feeding behaviors. Drosophila melanogaster has been a powerful genetic model for investigating how various chemical cues are detected at the molecular and cellular levels. In addition to an understanding of how tastants belonging to five historically described taste modalities (sweet, bitter, acid, salt, and amino acid) are sensed, recent findings have identified taste neurons and receptors that recognize tastants of non-canonical modalities, including fatty acids, carbonated water, polyamines, H2O2, bacterial lipopolysaccharide (LPS), ammonia, and calcium. Analyses of response profiles of taste neurons expressing different suites of chemosensory receptors have allowed exploration of taste coding mechanisms in primary sensory neurons. In this review, we present the current knowledge of the molecular and cellular basis of taste detection of various categories of tastants. We also summarize evidence for organotopic and multimodal functions of the taste system. Functional characterization of peripheral taste neurons in different organs has greatly increased our understanding of how insect behavior is regulated by the gustatory system, which may inform development of novel insect pest control strategies.
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Affiliation(s)
- Yu-Chieh David Chen
- Interdepartmental Neuroscience Program, University of California, Riverside, CA, 92521, USA
| | - Anupama Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, CA, 92521, USA.
- Department of Molecular, Cell and Systems Biology, University of California, 900 University Avenue, Riverside, CA, 92521, USA.
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Pamboro ELS, Brown EB, Keene AC. Dietary fatty acids promote sleep through a taste-independent mechanism. GENES BRAIN AND BEHAVIOR 2020; 19:e12629. [PMID: 31845509 DOI: 10.1111/gbb.12629] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 01/28/2023]
Abstract
Consumption of foods that are high in fat contribute to obesity and metabolism-related disorders. Dietary lipids are comprised of triglycerides and fatty acids, and the highly palatable taste of dietary fatty acids promotes food consumption, activates reward centers in mammals and underlies hedonic feeding. Despite the central role of dietary fats in the regulation of food intake and the etiology of metabolic diseases, little is known about how fat consumption regulates sleep. The fruit fly, Drosophila melanogaster, provides a powerful model system for the study of sleep and metabolic traits, and flies potently regulate sleep in accordance with food availability. To investigate the effects of dietary fats on sleep regulation, we have supplemented fatty acids into the diet of Drosophila and measured their effects on sleep and activity. We found that flies fed a diet of hexanoic acid, a medium-chain fatty acid that is a by-product of yeast fermentation, slept more than flies starved on an agar diet. To assess whether dietary fatty acids regulate sleep through the taste system, we assessed sleep in flies with a mutation in the hexanoic acid receptor Ionotropic receptor 56D, which is required for fatty acid taste perception. We found that these flies also sleep more than agar-fed flies when fed a hexanoic acid diet, suggesting the sleep promoting effect of hexanoic acid is not dependent on sensory perception. Taken together, these findings provide a platform to investigate the molecular and neural basis for fatty acid-dependent modulation of sleep.
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Affiliation(s)
- Estelle L S Pamboro
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
| | - Elizabeth B Brown
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
| | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
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Shan S, Wang SN, Song X, Khashaveh A, Lu ZY, Dhiloo KH, Li RJ, Gao XW, Zhang YJ. Antennal ionotropic receptors IR64a1 and IR64a2 of the parasitoid wasp Microplitis mediator (Hymenoptera: Braconidate) collaboratively perceive habitat and host cues. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 114:103204. [PMID: 31422151 DOI: 10.1016/j.ibmb.2019.103204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 07/15/2019] [Accepted: 07/25/2019] [Indexed: 05/12/2023]
Abstract
Ionotropic receptors (IRs), as a member of the conserved chemoreceptor families in the peripheral nervous system, play a critical role in the chemoreception of Drosophila. However, little is known about IRs in Hymenoptera insects. Here, we comprehensively characterized the gene structure, topological map and chemosensory roles of antennal IRs (MmedIRs) in the hymenopteran parasitoid wasp Microplitis mediator. We found that the IRs were conserved across various insect species. In the in situ hybridization assays, most IRs showed female antennae biased features, and there was no co-expression of the IRs and the olfactory receptor co-receptor (ORco). Moreover, three IR co-expressed complexes, IR75u-IR8a, IR64a1-IR8a and IR64a2-IR8a, were detected. Two genes with high similarity, IR64a1 and IR64a2, were located in distinct neurons but projected to the same sensillum. In two-electrode voltage-clamp recordings, IR64a1 was widely tuned to the chemicals from habitat cues released from host plants over long distances, whereas IR64a2 responded to a narrow range host cues and plant odors with low-volatility. Notably, IR64a2 was able to perceive Z9-14: Ald, a vital sex pheromone component that is released from Helicoverpa armigera, which is the preferred host of M. mediator. Furthermore, most ligands of IR64a1 and IR64a2 can trigger electrophysiological responses in female wasps. We propose that IR64a1 and IR64a2 collaboratively perceive habitat and host cues to assist parasitoids in efficiently seeking hosts.
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Affiliation(s)
- Shuang Shan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China; College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Shan-Ning Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China; Institute of Plant and Environment Protection, Beijing Academy of Agricultural and Forestry Sciences, Beijing, 100097, China
| | - Xuan Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China; College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, China
| | - Adel Khashaveh
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Zi-Yun Lu
- IPM Center of Hebei Province, Key Laboratory of Integrated Pest Management on Crops in Northern Region of North China, Ministry of Agriculture, Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, Baoding, 071000, China
| | - Khalid Hussain Dhiloo
- Department of Entomology, Faculty of Crop Protection, Sindh Agriculture University, Tandojam, 70060, Pakistan
| | - Rui-Jun Li
- College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, China
| | - Xi-Wu Gao
- College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Yong-Jun Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
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Cui Y, Kang C, Wu Z, Lin J. Identification and Expression Analyses of Olfactory Gene Families in the Rice Grasshopper, Oxya chinensis, From Antennal Transcriptomes. Front Physiol 2019; 10:1223. [PMID: 31616318 PMCID: PMC6775195 DOI: 10.3389/fphys.2019.01223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 09/09/2019] [Indexed: 11/13/2022] Open
Abstract
The rice grasshopper Oxya chinensis is an important agricultural pest of rice and other gramineous plants. Chemosensory genes are crucial factors in direct interactions with odorants in the olfactory process. Here we identified genes encoding 18 odorant-binding proteins (OBPs), 13 chemosensory proteins (CSPs), 94 olfactory receptors (ORs), 12 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs) from O. chinensis using an transcriptomic approach. Semi-quantitative RT-PCR assays revealed that six OBP-encoding genes (OchiOBP4, 5, 8, 9, 10, and 14), one CSP gene (OchiOBP10) and two IR genes (OchiIR28 and 29) were exclusively expressed in antennae, suggesting their roles in olfaction. Real-time quantitative PCR analyses revealed that genes expressed exclusively or predominantly in antennae also displayed significant differences in expression levels between males and females. Among the differentially expressed genes, 17 OR-encoding genes, one CSP- and one SNMP-gene showed female-biased expression, suggesting that they may be involved in some female-specific behaviors such as seeking oviposition site; whereas the three remaining OR-encoding genes showed male-biased expression, indicating their possible roles in sensing female sex pheromones. Our results laid a solid foundation for future studies to reveal olfactory mechanisms as well as designing strategies for controlling this rice pest.
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Affiliation(s)
- Yang Cui
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Cong Kang
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Zhongzhen Wu
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
| | - Jintian Lin
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, China
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Wu Z, Kang C, Qu M, Chen J, Chen M, Bin S, Lin J. Candidates for chemosensory genes identified in the Chinese citrus fly, Bactrocera minax, through a transcriptomic analysis. BMC Genomics 2019; 20:646. [PMID: 31412763 PMCID: PMC6693287 DOI: 10.1186/s12864-019-6022-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 08/09/2019] [Indexed: 11/10/2022] Open
Abstract
Background The males of many Bactrocera species (Diptera: Tephritidae) respond strongly to plant-derived chemicals (male lures) and can be divided into cue lure/raspberry ketone (CL/RK) responders, methyl eugenol (ME) responders and non-responders. Representing a non-responders, Bactrocera minax display unique olfactory sensory characteristics compared with other Bactrocera species. The chemical senses of insects mediate behaviors that are associated with survival and reproduction. Here, we report the generation of transcriptomes from antennae and the rectal glands of both male and female adults of B. minax using Illumina sequencing technology, and annotated gene families potentially responsible for chemosensory. Results We developed four transcriptomes from different tissues of B. minax and identified a set of candidate genes potentially responsible for chemosensory by analyzing the transcriptomic data. The candidates included 40 unigenes coding for odorant receptors (ORs), 30 for ionotropic receptors (IRs), 17 for gustatory receptors (GRs), three for sensory neuron membrane proteins (SNMPs), 33 for odorant-binding proteins (OBPs), four for chemosensory proteins (CSPs). Sex- and tissue-specific expression profiles for candidate chemosensory genes were analyzed via transcriptomic data analyses, and expression profiles of all ORs and antennal IRs were investigated by real-time quantitative PCR (RT-qPCR). Phylogenetic analyses were also conducted on gene families and paralogs from other insect species together. Conclusions A large number of chemosensory genes were identified from transcriptomic data. Identification of these candidate genes and their expression profiles in various tissues provide useful information for future studies towards revealing their function in B. minax. Electronic supplementary material The online version of this article (10.1186/s12864-019-6022-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhongzhen Wu
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, People's Republic of China
| | - Cong Kang
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, People's Republic of China
| | - Mengqiu Qu
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, People's Republic of China
| | - Junlong Chen
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, People's Republic of China
| | - Mingshun Chen
- Department of Entomology, Kansas State University, Manhattan, KS, 66506, USA
| | - Shuying Bin
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, People's Republic of China
| | - Jintian Lin
- Guang Zhou City Key Laboratory of Subtropical Fruit Tree Outbreak Control, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, People's Republic of China.
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Xu B, Chung HY. Quantitative Structure-Activity Relationship Study of Bitter Di-, Tri- and Tetrapeptides Using Integrated Descriptors. Molecules 2019; 24:molecules24152846. [PMID: 31387305 PMCID: PMC6696392 DOI: 10.3390/molecules24152846] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/23/2019] [Accepted: 08/05/2019] [Indexed: 11/16/2022] Open
Abstract
New quantitative structure–activity relationship (QSAR) models for bitter peptides were built with integrated amino acid descriptors. Datasets contained 48 dipeptides, 52 tripeptides and 23 tetrapeptides with their reported bitter taste thresholds. Independent variables consisted of 14 amino acid descriptor sets. A bootstrapping soft shrinkage approach was utilized for variable selection. The importance of a variable was evaluated by both variable selecting frequency and standardized regression coefficient. Results indicated model qualities for di-, tri- and tetrapeptides with R2 and Q2 at 0.950 ± 0.002, 0.941 ± 0.001; 0.770 ± 0.006, 0.742 ± 0.004; and 0.972 ± 0.002, 0.956 ± 0.002, respectively. The hydrophobic C-terminal amino acid was the key determinant for bitterness in dipeptides, followed by the contribution of bulky hydrophobic N-terminal amino acids. For tripeptides, hydrophobicity of C-terminal amino acids and the electronic properties of the amino acids at the second position were important. For tetrapeptides, bulky hydrophobic amino acids at N-terminus, hydrophobicity and partial specific volume of amino acids at the second position, and the electronic properties of amino acids of the remaining two positions were critical. In summary, this study not only constructs reliable models for predicting the bitterness in different groups of peptides, but also facilitates better understanding of their structure-bitterness relationships and provides insights for their future studies.
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Affiliation(s)
- Biyang Xu
- Food and Nutritional Sciences Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Hau Yin Chung
- Food and Nutritional Sciences Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
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Devineni AV, Sun B, Zhukovskaya A, Axel R. Acetic acid activates distinct taste pathways in Drosophila to elicit opposing, state-dependent feeding responses. eLife 2019; 8:47677. [PMID: 31205005 PMCID: PMC6579511 DOI: 10.7554/elife.47677] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 05/17/2019] [Indexed: 12/18/2022] Open
Abstract
Taste circuits are genetically determined to elicit an innate appetitive or aversive response, ensuring that animals consume nutritious foods and avoid the ingestion of toxins. We have examined the response of Drosophila melanogaster to acetic acid, a tastant that can be a metabolic resource but can also be toxic to the fly. Our data reveal that flies accommodate these conflicting attributes of acetic acid by virtue of a hunger-dependent switch in their behavioral response to this stimulus. Fed flies show taste aversion to acetic acid, whereas starved flies show a robust appetitive response. These opposing responses are mediated by two different classes of taste neurons, the sugar- and bitter-sensing neurons. Hunger shifts the behavioral response from aversion to attraction by enhancing the appetitive sugar pathway as well as suppressing the aversive bitter pathway. Thus a single tastant can drive opposing behaviors by activating distinct taste pathways modulated by internal state. Our sense of taste is critical to our survival. Taste helps us to consume nutritious foods and avoid toxins. There are five basic taste categories: sweet, salty, bitter, sour, and umami or savory, a taste typical of protein-rich foods. Each taste category activates a distinct pathway in the brain, triggering specific feelings and behaviors. We normally find sugar, salt, and components of protein pleasant, and seek out foods with these tastes. By contrast, we often find overly bitter or sour tastes unpleasant and try to avoid them. As sour and bitter-tasting substances often contain toxins, this response helps to protect us from poisoning. Across the animal kingdom, these preferences are largely hardwired from birth. But the relationship between taste and nutrients is not always straightforward. Some substances can be toxic despite also containing useful nutrients. Overripe fruit, for example, is broken down by yeast and bacteria to produce acetic acid, or vinegar. Like other acids, acetic acid can be toxic. But for the fruit fly Drosophila melanogaster, also known as the vinegar fly, acetic acid from rotten fruit can be a valuable source of calories. So how do flies react to the taste of acetic acid? Devineni et al. show that, unlike other chemicals, acetic acid triggers different taste responses in flies depending on whether the insects are hungry. Well-fed flies find the taste repulsive, probably because it signals toxicity. But hungry flies find it attractive, presumably because of their overriding need for calories. Devineni et al. show that acetic acid activates both sugar-sensing and bitter-sensing pathways in the fly brain. Hunger increases activity in the sugar pathway and reduces it in the bitter pathway. As a result, hungry flies are attracted to acetic acid, whereas fully fed flies are repulsed. Flexibility in the taste system enables animals to react to the same substance in different ways depending on their current needs. Related to this, evidence suggests that obesity may be associated with altered sensitivity to certain tastes, such as sweet, as well as a blunted response to satiety signals. Understanding how the brain combines information about taste and hunger to control food consumption may ultimately help us to understand and treat obesity.
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Affiliation(s)
- Anita V Devineni
- Department of Neuroscience, The Mortimer B Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States
| | - Bei Sun
- Department of Neuroscience, The Mortimer B Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States
| | - Anna Zhukovskaya
- Department of Neuroscience, The Mortimer B Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States
| | - Richard Axel
- Department of Neuroscience, The Mortimer B Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States.,Howard Hughes Medical Institute, Columbia University, New York, United States
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He Z, Luo Y, Shang X, Sun JS, Carlson JR. Chemosensory sensilla of the Drosophila wing express a candidate ionotropic pheromone receptor. PLoS Biol 2019; 17:e2006619. [PMID: 31112532 PMCID: PMC6528970 DOI: 10.1371/journal.pbio.2006619] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 04/05/2019] [Indexed: 12/01/2022] Open
Abstract
The Drosophila wing was proposed to be a taste organ more than 35 years ago, but there has been remarkably little study of its role in chemoreception. We carry out a differential RNA-seq analysis of a row of sensilla on the anterior wing margin and find expression of many genes associated with pheromone and chemical perception. To ask whether these sensilla might receive pheromonal input, we devised a dye-transfer paradigm and found that large, hydrophobic molecules comparable to pheromones can be transferred from one fly to the wing margin of another. One gene, Ionotropic receptor (IR)52a, is coexpressed in neurons of these sensilla with fruitless, a marker of sexual circuitry; IR52a is also expressed in legs. Mutation of IR52a and optogenetic silencing of IR52a+ neurons decrease levels of male sexual behavior. Optogenetic activation of IR52a+ neurons induces males to show courtship toward other males and, remarkably, toward females of another species. Surprisingly, IR52a is also required in females for normal sexual behavior. Optogenetic activation of IR52a+ neurons in mated females induces copulation, which normally occurs at very low levels. Unlike other chemoreceptors that act in males to inhibit male–male interactions and promote male–female interactions, IR52a acts in both males and females, and can promote male–male as well as male–female interactions. Moreover, IR52a+ neurons can override the circuitry that normally suppresses sexual behavior toward unproductive targets. Circuit mapping and Ca2+ imaging using the trans-Tango system reveals second-order projections of IR52a+ neurons in the subesophageal zone (SEZ), some of which are sexually dimorphic. Optogenetic activation of IR52a+ neurons in the wing activates second-order projections in the SEZ. Taken together, this study provides a molecular description of the chemosensory sensilla of a greatly understudied taste organ and defines a gene that regulates the sexual circuitry of the fly.
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Affiliation(s)
- Zhe He
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Yichen Luo
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Xueying Shang
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Jennifer S. Sun
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - John R. Carlson
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
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40
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A single pair of leucokinin neurons are modulated by feeding state and regulate sleep-metabolism interactions. PLoS Biol 2019; 17:e2006409. [PMID: 30759083 PMCID: PMC6391015 DOI: 10.1371/journal.pbio.2006409] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 02/26/2019] [Accepted: 01/25/2019] [Indexed: 12/25/2022] Open
Abstract
Dysregulation of sleep and feeding has widespread health consequences. Despite extensive epidemiological evidence for interactions between sleep and metabolic function, little is known about the neural or molecular basis underlying the integration of these processes. D. melanogaster potently suppress sleep in response to starvation, and powerful genetic tools allow for mechanistic investigation of sleep–metabolism interactions. We have previously identified neurons expressing the neuropeptide leucokinin (Lk) as being required for starvation-mediated changes in sleep. Here, we demonstrate an essential role for Lk neuropeptide in metabolic regulation of sleep. The activity of Lk neurons is modulated by feeding, with reduced activity in response to glucose and increased activity under starvation conditions. Both genetic silencing and laser-mediated microablation localize Lk-dependent sleep regulation to a single pair of Lk neurons within the Lateral Horn (LHLK neurons). A targeted screen identified a role for 5′ adenosine monophosphate-activated protein kinase (AMPK) in starvation-modulated changes in sleep. Knockdown of AMPK in Lk neurons suppresses sleep and increases LHLK neuron activity in fed flies, phenocopying the starvation state. Further, we find a requirement for the Lk receptor in the insulin-producing cells (IPCs), suggesting LHLK–IPC connectivity is critical for sleep regulation under starved conditions. Taken together, these findings localize feeding-state–dependent regulation of sleep to a single pair of neurons within the fruit fly brain and provide a system for investigating the cellular basis of sleep–metabolism interactions. Neural regulation of sleep and feeding are interconnected and are critical for survival. Many animals reduce their sleep in response to starvation, presumably to forage for food. Here, we find that in the fruit fly Drosophila melanogaster, the neuropeptide leucokinin is required for the modulation of starvation-dependent changes in sleep. Leucokinin is expressed in numerous populations of neurons within the two compartments of the central nervous system: the brain and the ventral nerve cord. Both genetic manipulation and laser-mediated microablation experiments identify a single pair of neurons expressing this neuropeptide in the brain as being required for metabolic regulation of sleep. These neurons become active during periods of starvation and modulate the function of insulin-producing cells that are critical modulators of both sleep and feeding. Supporting this notion, knockdown of the leucokinin receptor within the insulin-producing cells also disrupts metabolic regulation of sleep. Taken together, these findings identify a critical role for leucokinin signaling in the integration of sleep and feeding states.
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Yanagawa A, Couto A, Sandoz JC, Hata T, Mitra A, Ali Agha M, Marion-Poll F. LPS perception through taste-induced reflex in Drosophila melanogaster. JOURNAL OF INSECT PHYSIOLOGY 2019; 112:39-47. [PMID: 30528842 DOI: 10.1016/j.jinsphys.2018.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/07/2018] [Accepted: 12/02/2018] [Indexed: 06/09/2023]
Abstract
In flies, grooming serves several purposes, including protection against pathogens and parasites. Previously, we found Escherichia coli or lipopolysaccharides (LPS) can induce grooming behavior via activation of contact chemoreceptors on Drosophila wing. This suggested that specific taste receptors may contribute to this detection. In this study, we examined the perception of commercially available LPS on Drosophila wing chemoreceptors in grooming reflex. Behavioral tests conducted with bitter, sweet and salty gustation such as caffeine, sucrose and salt, using flies carrying a defect in one of their taste receptors related to the detection of bitter molecules (Gr66a, Gr33a), sugars (Gr5a, Gr64f), or salt (IR76b). LPS and tastants of each category were applied to wing sensilla of these taste defectflies and to wild-type Canton Special (CS) flies. Our results indicate that the grooming reflex induced by LPS requires a wide range of gustatory genes, and the inactivation of any of tested genes expressing cells causes a significant reduction of the behavior. This suggests that, while the grooming reflex is strongly regulated by cues perceived as aversive, other sapid cues traditionally related to sweet and salty tastes are also contributing to this behavior.
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Affiliation(s)
- Aya Yanagawa
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan.
| | - Antoine Couto
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France
| | - Jean-Christophe Sandoz
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France
| | - Toshimitsu Hata
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - Aniruddha Mitra
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France; School of Biological & Environmental Sciences, Shoolini University, Solan, India
| | - Moutaz Ali Agha
- AgroParisTech, Université Paris-Saclay, Paris, France; Ÿnsect-Pôle Innovia, Damparis, France
| | - Frédéric Marion-Poll
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France; AgroParisTech, Université Paris-Saclay, Paris, France.
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Sánchez-Alcañiz JA, Silbering AF, Croset V, Zappia G, Sivasubramaniam AK, Abuin L, Sahai SY, Münch D, Steck K, Auer TO, Cruchet S, Neagu-Maier GL, Sprecher SG, Ribeiro C, Yapici N, Benton R. An expression atlas of variant ionotropic glutamate receptors identifies a molecular basis of carbonation sensing. Nat Commun 2018; 9:4252. [PMID: 30315166 PMCID: PMC6185939 DOI: 10.1038/s41467-018-06453-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Through analysis of the Drosophila ionotropic receptors (IRs), a family of variant ionotropic glutamate receptors, we reveal that most IRs are expressed in peripheral neuron populations in diverse gustatory organs in larvae and adults. We characterise IR56d, which defines two anatomically-distinct neuron classes in the proboscis: one responds to carbonated solutions and fatty acids while the other represents a subset of sugar- and fatty acid-sensing cells. Mutational analysis indicates that IR56d, together with the broadly-expressed co-receptors IR25a and IR76b, is essential for physiological responses to carbonation and fatty acids, but not sugars. We further demonstrate that carbonation and fatty acids both promote IR56d-dependent attraction of flies, but through different behavioural outputs. Our work provides a toolkit for investigating taste functions of IRs, defines a subset of these receptors required for carbonation sensing, and illustrates how the gustatory system uses combinatorial expression of sensory molecules in distinct neurons to coordinate behaviour. Little is known about the role of variant ionotropic glutamate receptors (IRs) in insect taste. Here the authors characterise the expression pattern of IRs in the Drosophila gustatory system and highlight the role of one receptor, IR56d, in the detection of carbonation
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Affiliation(s)
- Juan Antonio Sánchez-Alcañiz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Ana Florencia Silbering
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Vincent Croset
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland.,Centre for Neural Circuits and Behaviour, University of Oxford, Tinsley Building, Mansfield Road, Oxford, OX1 3SR, United Kingdom
| | - Giovanna Zappia
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Anantha Krishna Sivasubramaniam
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Liliane Abuin
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Saumya Yashmohini Sahai
- Department of Neurobiology and Behavior, Cornell University, W153 Mudd Hall, Ithaca, NY, 14853, USA
| | - Daniel Münch
- Champalimaud Centre for the Unknown, Lisbon, 1400-038, Portugal
| | - Kathrin Steck
- Champalimaud Centre for the Unknown, Lisbon, 1400-038, Portugal
| | - Thomas O Auer
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - Steeve Cruchet
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland
| | - G Larisa Neagu-Maier
- Department of Biology, Institute of Zoology, University of Fribourg, Chemin du Musée 10, Fribourg, CH-1700, Switzerland
| | - Simon G Sprecher
- Department of Biology, Institute of Zoology, University of Fribourg, Chemin du Musée 10, Fribourg, CH-1700, Switzerland
| | - Carlos Ribeiro
- Champalimaud Centre for the Unknown, Lisbon, 1400-038, Portugal
| | - Nilay Yapici
- Department of Neurobiology and Behavior, Cornell University, W153 Mudd Hall, Ithaca, NY, 14853, USA
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland.
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43
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Gomez-Diaz C, Martin F, Garcia-Fernandez JM, Alcorta E. The Two Main Olfactory Receptor Families in Drosophila, ORs and IRs: A Comparative Approach. Front Cell Neurosci 2018; 12:253. [PMID: 30214396 PMCID: PMC6125307 DOI: 10.3389/fncel.2018.00253] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/23/2018] [Indexed: 12/20/2022] Open
Abstract
Most insect species rely on the detection of olfactory cues for critical behaviors for the survival of the species, e.g., finding food, suitable mates and appropriate egg-laying sites. Although insects show a diverse array of molecular receptors dedicated to the detection of sensory cues, two main types of molecular receptors have been described as responsible for olfactory reception in Drosophila, the odorant receptors (ORs) and the ionotropic receptors (IRs). Although both receptor families share the role of being the first chemosensors in the insect olfactory system, they show distinct evolutionary origins and several distinct structural and functional characteristics. While ORs are seven-transmembrane-domain receptor proteins, IRs are related to the ionotropic glutamate receptor (iGluR) family. Both types of receptors are expressed on the olfactory sensory neurons (OSNs) of the main olfactory organ, the antenna, but they are housed in different types of sensilla, IRs in coeloconic sensilla and ORs in basiconic and trichoid sensilla. More importantly, from the functional point of view, they display different odorant specificity profiles. Research advances in the last decade have improved our understanding of the molecular basis, evolution and functional roles of these two families, but there are still controversies and unsolved key questions that remain to be answered. Here, we present an updated review on the advances of the genetic basis, evolution, structure, functional response and regulation of both types of chemosensory receptors. We use a comparative approach to highlight the similarities and differences among them. Moreover, we will discuss major open questions in the field of olfactory reception in insects. A comprehensive analysis of the structural and functional convergence and divergence of both types of receptors will help in elucidating the molecular basis of the function and regulation of chemoreception in insects.
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Affiliation(s)
- Carolina Gomez-Diaz
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
| | - Fernando Martin
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
| | | | - Esther Alcorta
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
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44
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Genome-based identification and analysis of ionotropic receptors in Spodoptera litura. Naturwissenschaften 2018; 105:38. [DOI: 10.1007/s00114-018-1563-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/06/2018] [Accepted: 05/08/2018] [Indexed: 01/09/2023]
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45
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Lowenstein EG, Velazquez-Ulloa NA. A Fly's Eye View of Natural and Drug Reward. Front Physiol 2018; 9:407. [PMID: 29720947 PMCID: PMC5915475 DOI: 10.3389/fphys.2018.00407] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 04/04/2018] [Indexed: 12/18/2022] Open
Abstract
Animals encounter multiple stimuli each day. Some of these stimuli are innately appetitive or aversive, while others are assigned valence based on experience. Drugs like ethanol can elicit aversion in the short term and attraction in the long term. The reward system encodes the predictive value for different stimuli, mediating anticipation for attractive or punishing stimuli and driving animal behavior to approach or avoid conditioned stimuli. The neurochemistry and neurocircuitry of the reward system is partly evolutionarily conserved. In both vertebrates and invertebrates, including Drosophila melanogaster, dopamine is at the center of a network of neurotransmitters and neuromodulators acting in concert to encode rewards. Behavioral assays in D. melanogaster have become increasingly sophisticated, allowing more direct comparison with mammalian research. Moreover, recent evidence has established the functional modularity of the reward neural circuits in Drosophila. This functional modularity resembles the organization of reward circuits in mammals. The powerful genetic and molecular tools for D. melanogaster allow characterization and manipulation at the single-cell level. These tools are being used to construct a detailed map of the neural circuits mediating specific rewarding stimuli and have allowed for the identification of multiple genes and molecular pathways that mediate the effects of reinforcing stimuli, including their rewarding effects. This report provides an overview of the research on natural and drug reward in D. melanogaster, including natural rewards such as sugar and other food nutrients, and drug rewards including ethanol, cocaine, amphetamine, methamphetamine, and nicotine. We focused mainly on the known genetic and neural mechanisms underlying appetitive reward for sugar and reward for ethanol. We also include genes, molecular pathways, and neural circuits that have been identified using assays that test the palatability of the rewarding stimulus, the preference for the rewarding stimulus, or other effects of the stimulus that indicate how it can modify behavior. Commonalities between mechanisms of natural and drug reward are highlighted and future directions are presented, putting forward questions best suited for research using D. melanogaster as a model organism.
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Affiliation(s)
- Eve G Lowenstein
- Department of Biology, Lewis & Clark College, Portland, OR, United States
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Steck K, Walker SJ, Itskov PM, Baltazar C, Moreira JM, Ribeiro C. Internal amino acid state modulates yeast taste neurons to support protein homeostasis in Drosophila. eLife 2018; 7:31625. [PMID: 29393045 PMCID: PMC5812714 DOI: 10.7554/elife.31625] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/19/2018] [Indexed: 12/21/2022] Open
Abstract
To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfills most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. Here we identify a class of proboscis GRNs required for yeast intake. Within this class, taste peg GRNs are specifically required to sustain yeast feeding. Sensillar GRNs, however, mediate feeding initiation. Furthermore, the response of yeast GRNs, but not sweet GRNs, is enhanced following deprivation from amino acids, providing a potential basis for protein-specific appetite. Although nutritional and reproductive states synergistically increase yeast appetite, reproductive state acts independently of nutritional state, modulating processing downstream of GRNs. Together, these results suggest that different internal states act at distinct levels of a dedicated gustatory circuit to elicit nutrient-specific appetites towards a complex, ecologically relevant protein source. When animals run low on a certain nutrient, they change their behavior to seek out and feed on foods rich in that missing element. For example, fruit flies lacking sugar will look for and eat more sweet food; if they need proteins, they will instead favor yeast, flies’ principal source of proteins. In fruit flies, certain neurons on the insects’ tongue (or proboscis) are dedicated only to taste. These cells are divided in groups specialized for a type of nutrient – for instance some of them only react to sugar. Taste neurons sense food and help coordinate how much and for how long the animals will feed. However, despite how important proteins are for flies, the neurons dedicated to tasting yeast had yet to be identified. Here, Steck, Walker et al. report discovering a new set of taste neurons in fruit flies, which are activated by a unique combination of molecules present in yeast. Crucially, without these neurons being active, the insects can no longer adjust their diet to eat more yeast when they are deprived of proteins. The activity of these cells is also regulated by internal levels of nutrients derived from proteins. The yeast-specific taste neurons are present in two areas on the fly’s proboscis, which is used like a straw when feeding. The two sets of cells have different roles in the consumption of yeast. The first group, which is located at the extremity of the proboscis, helps flies detect and start consuming the resource. The second group, which is on the inner surface of the proboscis, influences whether the insects keep feeding. If one of these groups of neurons is deactivated, flies continue to eat yeast as normal, showing that the system is redundant. However, if both sets are turned off artificially, the insects stop favoring yeast even when they are in need of proteins. Steck, Walker et al. show how the animals’ internal states also influence the activity of these neurons. When the insects are deprived of molecules that are only found in proteins, these newly discovered neurons are primed to react more strongly when they are exposed to yeast. This potentially makes flies eat more yeast, and as a result consume more proteins. Many biological systems in flies are similar in other insects and even humans. If this is the case for these taste neurons, fruit flies could be a good model to study how pests such as locusts and mosquitoes are attracted to the proteins in crops and blood, but also how humans make decisions about food.
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Affiliation(s)
- Kathrin Steck
- Champalimaud Centre for the Unknown, Lisbon, Portugal
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