1
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Xue Q, Hasan KS, Dweck O, Ebrahim SAM, Dweck HKM. Functional characterization and evolution of olfactory responses in coeloconic sensilla of the global fruit pest Drosophila suzukii. BMC Biol 2025; 23:50. [PMID: 39985002 PMCID: PMC11846463 DOI: 10.1186/s12915-025-02151-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2024] [Accepted: 02/07/2025] [Indexed: 02/23/2025] Open
Abstract
BACKGROUND When a species changes its host preference, it often requires modifications in its sensory systems. Many of these changes remain largely uninvestigated in the global fruit pest Drosophila suzukii (also known as spotted wing Drosophila, SWD). This species, which shares a last common ancestor with the model organism D. melanogaster-a species that prefers overripe fruits- ~ 15 million years ago, has shifted its preference from overripe to ripe, soft-skinned fruits, causing significant damage to fruit industries worldwide. RESULTS Here, we functionally characterized the coeloconic sensilla in D. suzukii and compared their responses to those of its close relatives, D. biarmipes and D. melanogaster. We find that D. suzukii's responses are grouped into four functional types. These responses are consistent across sexes and reproductive status. The odorant receptor co-receptor Orco is required for certain responses. Comparative analysis across these species revealed evolutionary changes in physiological and behavioral responses to specific odorants, such as acetic acid, a key indicator of microbial fermentation, and phenylacetaldehyde, an aromatic compound found in a diverse range of fruits. Phenylacetaldehyde produced lower electrophysiological responses in D. suzukii compared to D. melanogaster and elicited strong attraction in D. suzukii but not in any of the other tested species. CONCLUSIONS The olfactory changes identified in this study likely play a significant role in the novel behavior of D. suzukii. This work also identifies phenylacetaldehyde as a potent attractant for D. suzukii, which can be used to develop targeted management strategies to mitigate the serious impact of this pest.
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Affiliation(s)
- Qi Xue
- Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, CT, 06511, USA
| | - Kazi Sifat Hasan
- Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, CT, 06511, USA
| | - Omar Dweck
- Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, CT, 06511, USA
- Wilbur Cross High School, 181 Mitchell Dr, New Haven, CT, 06511, USA
| | - Shimaa A M Ebrahim
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06511, USA
| | - Hany K M Dweck
- Department of Entomology, The Connecticut Agricultural Experiment Station, New Haven, CT, 06511, USA.
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2
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Walker SR, Peña-Garcia M, Devineni AV. Connectomic analysis of taste circuits in Drosophila. Sci Rep 2025; 15:5278. [PMID: 39939650 PMCID: PMC11821855 DOI: 10.1038/s41598-025-89088-9] [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: 09/20/2024] [Accepted: 02/03/2025] [Indexed: 02/14/2025] Open
Abstract
Our sense of taste is critical for regulating food consumption. The fruit fly Drosophila represents a highly tractable model to investigate mechanisms of taste processing, but taste circuits beyond sensory neurons are largely unidentified. Here, we use a whole-brain connectome to investigate the organization of Drosophila taste circuits. We trace pathways from four populations of sensory neurons that detect different taste modalities and project to the subesophageal zone (SEZ), the primary taste region of the fly brain. We find that second-order taste neurons are primarily located within the SEZ and largely segregated by taste modality, whereas third-order neurons have more projections outside the SEZ and more overlap between modalities. Taste projections out of the SEZ innervate regions implicated in feeding, olfactory processing, and learning. We analyze interconnections within and between taste pathways, characterize modality-dependent differences in taste neuron properties, identify other types of inputs onto taste pathways, and use computational simulations to relate neuronal connectivity to predicted activity. These studies provide insight into the architecture of Drosophila taste circuits.
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Affiliation(s)
- Sydney R Walker
- Department of Biology, Emory University, Atlanta, GA, 30322, USA
| | - Marco Peña-Garcia
- Neuroscience Graduate Program, Emory University, Atlanta, GA, 30322, USA
| | - Anita V Devineni
- Department of Biology, Emory University, Atlanta, GA, 30322, USA.
- Neuroscience Graduate Program, Emory University, Atlanta, GA, 30322, USA.
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3
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Huda A, Vaden TJ, Bai H, Rawls RT, Peppers RJ, Monck CF, Holley HD, Castaneda AN, Ni L. Behavioral Assays for Optogenetic Manipulation of Neural Circuits in Drosophila melanogaster. J Vis Exp 2025:10.3791/67964. [PMID: 39995158 PMCID: PMC12051042 DOI: 10.3791/67964] [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: 02/26/2025] Open
Abstract
Optogenetics has become a fundamental technique in neuroscience, enabling precise control of neuronal activity through light stimulation. This study introduces easy-to-implement setups for applying optogenetic methods in Drosophila melanogaster. Two optogenetic tools, CsChrimson, a red-light-activated cation channel, and GtACR2, a blue-light-activated anion channel, were employed in four experimental approaches. Three of these approaches involve single-fly experiments: (1) a blue-light optogenetic thermotactic positional preference assay targeting temperature-sensitive heating cells, (2) a red-light optogenetic positional preference assay activating bitter sensing neurons, and (3) a proboscis extension response assay activating the sweet-sensing neurons. The fourth approach (4) is a fly maze setup to assess avoidance behaviors using multiple flies. The ability to manipulate neural activity temporally and spatially offers powerful insights into sensory processing and decision-making, underscoring the potential of optogenetics to advance our knowledge of neural function. These methods provide an accessible and robust framework for future research in neuroscience to enhance the understanding of specific neural pathways and their behavioral outcomes.
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Affiliation(s)
| | | | - Hua Bai
- School of Neuroscience, Virginia Tech
| | | | | | | | | | - Allison N Castaneda
- School of Neuroscience, Virginia Tech; Fairfax County Public Schools, Westfield High School
| | - Lina Ni
- School of Neuroscience, Virginia Tech;
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4
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Shuai Y, Sammons M, Sterne GR, Hibbard KL, Yang H, Yang CP, Managan C, Siwanowicz I, Lee T, Rubin GM, Turner GC, Aso Y. Driver lines for studying associative learning in Drosophila. eLife 2025; 13:RP94168. [PMID: 39879130 PMCID: PMC11778931 DOI: 10.7554/elife.94168] [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: 01/31/2025] Open
Abstract
The mushroom body (MB) is the center for associative learning in insects. In Drosophila, intersectional split-GAL4 drivers and electron microscopy (EM) connectomes have laid the foundation for precise interrogation of the MB neural circuits. However, investigation of many cell types upstream and downstream of the MB has been hindered due to lack of specific driver lines. Here we describe a new collection of over 800 split-GAL4 and split-LexA drivers that cover approximately 300 cell types, including sugar sensory neurons, putative nociceptive ascending neurons, olfactory and thermo-/hygro-sensory projection neurons, interneurons connected with the MB-extrinsic neurons, and various other cell types. We characterized activation phenotypes for a subset of these lines and identified a sugar sensory neuron line most suitable for reward substitution. Leveraging the thousands of confocal microscopy images associated with the collection, we analyzed neuronal morphological stereotypy and discovered that one set of mushroom body output neurons, MBON08/MBON09, exhibits striking individuality and asymmetry across animals. In conjunction with the EM connectome maps, the driver lines reported here offer a powerful resource for functional dissection of neural circuits for associative learning in adult Drosophila.
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Affiliation(s)
- Yichun Shuai
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Megan Sammons
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Gabriella R Sterne
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Karen L Hibbard
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - He Yang
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Ching-Po Yang
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Claire Managan
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Igor Siwanowicz
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Tzumin Lee
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Gerald M Rubin
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Glenn C Turner
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Yoshinori Aso
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
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5
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Walker SR, Peña-Garcia M, Devineni AV. Connectomic analysis of taste circuits in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.14.613080. [PMID: 39314399 PMCID: PMC11419157 DOI: 10.1101/2024.09.14.613080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Our sense of taste is critical for regulating food consumption. The fruit fly Drosophila represents a highly tractable model to investigate mechanisms of taste processing, but taste circuits beyond sensory neurons are largely unidentified. Here, we use a whole-brain connectome to investigate the organization of Drosophila taste circuits. We trace pathways from four populations of sensory neurons that detect different taste modalities and project to the subesophageal zone (SEZ). We find that second-order taste neurons are primarily located within the SEZ and largely segregated by taste modality, whereas third-order neurons have more projections outside the SEZ and more overlap between modalities. Taste projections out of the SEZ innervate regions implicated in feeding, olfactory processing, and learning. We characterize interconnections between taste pathways, identify modality-dependent differences in taste neuron properties, and use computational simulations to relate connectivity to predicted activity. These studies provide insight into the architecture of Drosophila taste circuits.
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Affiliation(s)
- Sydney R. Walker
- Department of Biology, Emory University, Atlanta GA 30322
- These authors contributed equally
| | - Marco Peña-Garcia
- Neuroscience Graduate Program, Emory University, Atlanta GA 30322
- These authors contributed equally
| | - Anita V. Devineni
- Department of Biology, Emory University, Atlanta GA 30322
- Neuroscience Graduate Program, Emory University, Atlanta GA 30322
- Lead contact
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6
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Afkhami M. Neurobiology of egg-laying behavior in Drosophila: neural control of the female reproductive system. J Neurogenet 2024; 38:47-61. [PMID: 39250036 DOI: 10.1080/01677063.2024.2396352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/20/2024] [Indexed: 09/10/2024]
Abstract
Egg-laying is one of the key aspects of female reproductive behavior in insects. Egg-laying has been studied since the dawn of Drosophila melanogaster as a model organism. The female's internal state, hormones, and external factors, such as nutrition, light, and social environment, affect egg-laying output. However, only recently, neurobiological features of egg-laying behavior have been studied in detail. fruitless and doublesex, two key players in the sex determination pathway, have become focal points in identifying neurons of reproductive significance in both central and peripheral nervous systems. The reproductive tract and external terminalia house sensory neurons that carry the sensory information of egg maturation, mating and egg-laying. These sensory signals include the presence of male accessory gland products and mechanical stimuli. The abdominal neuromere houses neurons that receive information from the reproductive tract, including sex peptide abdominal ganglion neurons (SAGs), and send their information to the brain. In the brain, neuronal groups like aDNs and pC1 clusters modulate egg-laying decision-making, and other neurons like oviINs and oviDNs are necessary for egg-laying itself. Lastly, motor neurons involved in egg-laying, which are mostly octopaminergic, reside in the abdominal neuromere and orchestrate the muscle movements required for laying the egg. Egg-laying neuronal control is important in various evolutionary processes like cryptic female choice, and using different Drosophila species can provide intriguing avenues for the future of the field.
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Affiliation(s)
- Mehrnaz Afkhami
- School of Biological Sciences, University of Oklahoma, Norman, OK, USA
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7
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Guillemin J, Li J, Li V, McDowell SAT, Audette K, Davis G, Jelen M, Slamani S, Kelliher L, Gordon MD, Stanley M. Taste cells expressing Ionotropic Receptor 94e reciprocally impact feeding and egg laying in Drosophila. Cell Rep 2024; 43:114625. [PMID: 39141516 DOI: 10.1016/j.celrep.2024.114625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 06/01/2024] [Accepted: 07/30/2024] [Indexed: 08/16/2024] Open
Abstract
Chemosensory cells across the body of Drosophila melanogaster evaluate the environment to prioritize certain behaviors. Previous mapping of gustatory receptor neurons (GRNs) on the fly labellum identified a set of neurons in L-type sensilla that express Ionotropic Receptor 94e (IR94e), but the impact of IR94e GRNs on behavior remains unclear. We used optogenetics and chemogenetics to activate IR94e neurons and found that they drive mild feeding suppression but enhance egg laying. In vivo calcium imaging revealed that IR94e GRNs respond strongly to certain amino acids, including glutamate, and that IR94e plus co-receptors IR25a and IR76b are required for amino acid detection. Furthermore, IR94e mutants show behavioral changes to solutions containing amino acids, including increased consumption and decreased egg laying. Overall, our results suggest that IR94e GRNs on the fly labellum discourage feeding and encourage egg laying as part of an important behavioral switch in response to certain chemical cues.
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Affiliation(s)
| | - Jinfang Li
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Viktoriya Li
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Sasha A T McDowell
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Kayla Audette
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Grace Davis
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Meghan Jelen
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Samy Slamani
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Liam Kelliher
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA
| | - Michael D Gordon
- Department of Zoology, Life Sciences Institute and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
| | - Molly Stanley
- Department of Biology, The University of Vermont, Burlington, VT 05405, USA.
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8
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Banse SA, Jarrett CM, Robinson KJ, Blue BW, Shaw EL, Phillips PC. The egg-counter: a novel microfluidic platform for characterization of Caenorhabditis elegans egg-laying. LAB ON A CHIP 2024; 24:2975-2986. [PMID: 38738514 PMCID: PMC11131562 DOI: 10.1039/d3lc01073b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 04/20/2024] [Indexed: 05/14/2024]
Abstract
Reproduction is a fundamental process that shapes the demography of every living organism yet is often difficult to assess with high precision in animals that produce large numbers of offspring. Here, we present a novel microfluidic research platform for studying Caenorhabditis elegans' egg-laying. The platform provides higher throughput than traditional solid-media behavioral assays while providing a very high degree of temporal resolution. Additionally, the environmental control enabled by microfluidic animal husbandry allows for experimental perturbations difficult to achieve with solid-media assays. We demonstrate the platform's utility by characterizing C. elegans egg-laying behavior at two commonly used temperatures, 15 and 20 °C. As expected, we observed a delayed onset of egg-laying at 15 °C degrees, consistent with published temperature effects on development rate. Additionally, as seen in solid media studies, egg laying output was higher under the canonical 20 °C conditions. While we validated the Egg-Counter with a study of temperature effects in wild-type animals, the platform is highly adaptable to any nematode egg-laying research where throughput or environmental control needs to be maximized without sacrificing temporal resolution.
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Affiliation(s)
- Stephen A Banse
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Cody M Jarrett
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Kristin J Robinson
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Benjamin W Blue
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Emily L Shaw
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
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9
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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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10
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Peláez JN, Bernstein S, Okoro J, Rodas E, Liang I, Leipertz A, Marion-Poll F, Whiteman NK. Taste evolution in an herbivorous drosophilid. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.27.582299. [PMID: 38464294 PMCID: PMC10925181 DOI: 10.1101/2024.02.27.582299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Plant secondary metabolites pose a challenge for generalist herbivorous insects because they are not only potentially toxic, they also may trigger aversion. On the contrary, some highly specialized herbivorous insects evolved to use these same compounds as 'token stimuli' for unambiguous determination of their host plants. Two questions that emerge from these observations are how recently derived herbivores evolve to overcome this aversion to plant secondary metabolites and the extent to which they evolve increased attraction to these same compounds. In this study, we addressed these questions by focusing on the evolution of bitter taste preferences in the herbivorous drosophilid Scaptomyza flava, which is phylogenetically nested deep in the paraphyletic Drosophila. We measured behavioral and neural responses of S. flava and a set of non-herbivorous species representing a phylogenetic gradient (S. pallida, S. hsui, and D. melanogaster) towards host- and non-host derived bitter plant compounds. We observed that S. flava evolved a shift in bitter detection, rather than a narrow shift towards glucosinolates, the precursors of mustard-specific defense compounds. In a dye-based consumption assay, S. flava exhibited shifts in aversion toward the non-mustard bitter, plant-produced alkaloids caffeine and lobeline, and reduced aversion towards glucosinolates, whereas the non-herbivorous species each showed strong aversion to all bitter compounds tested. We then examined whether these changes in bitter preferences of S. flava could be explained by changes in sensitivity in the peripheral nervous system and compared electrophysiological responses from the labellar sensilla of S. flava, S. pallida, and D. melanogaster. Using scanning electron microscopy, we also created a map of labellar sensilla in S. flava and S. pallida. We assigned each sensillum to a functional sensilla class based on their morphology and initial response profiles to bitter and sweet compounds. Despite a high degree of conservation in the morphology and spatial placement of sensilla between S. flava and S. pallida, electrophysiological studies revealed that S. flava had reduced sensitivity to glucosinolates to varying degrees. We found this reduction only in I type sensilla. Finally, we speculate on the potential role that evolutionary genetic changes in gustatory receptors between S. pallida and S. flava may play in driving these patterns. Specifically, we hypothesize that the evolution of bitter receptors expressed in I type sensilla may have driven the reduced sensitivity observed in S. flava, and ultimately, its reduced bitter aversion. The S. flava system showcases the importance of reduced aversion to bitter defense compounds in relatively young herbivorous lineages, and how this may be achieved at the molecular and physiological level.
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Affiliation(s)
- Julianne N. Peláez
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Susan Bernstein
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Judith Okoro
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Esteban Rodas
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Irene Liang
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Anna Leipertz
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Frédéric Marion-Poll
- Evolution, Genomes, Behaviour and Ecology, IDEEV, CNRS, Université Paris-Saclay, IRD, Gif-sur-Yvette, France
- Université Paris-Saclay, AgroParisTech, 91120 Palaiseau, France
| | - Noah K. Whiteman
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Molecular & Cellular Biology, University of California-Berkeley, Berkeley, CA 94720, USA
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11
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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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12
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Oliveira-Ferreira C, Gaspar M, Vasconcelos ML. Neuronal substrates of egg-laying behaviour at the abdominal ganglion of Drosophila melanogaster. Sci Rep 2023; 13:21941. [PMID: 38081887 PMCID: PMC10713638 DOI: 10.1038/s41598-023-48109-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/22/2023] [Indexed: 12/18/2023] Open
Abstract
Egg-laying in Drosophila is the product of post-mating physiological and behavioural changes that culminate in a stereotyped sequence of actions. Egg-laying harbours a great potential as a paradigm to uncover how the appropriate motor circuits are organized and activated to generate behaviour. To study this programme, we first describe the different phases of the egg-laying programme and the specific actions associated with each phase. Using a combination of neuronal activation and silencing experiments, we identify neurons (OvAbg) in the abdominal ganglion as key players in egg-laying. To generate and functionally characterise subsets of OvAbg, we used an intersectional approach with neurotransmitter specific lines-VGlut, Cha and Gad1. We show that OvAbg/VGlut neurons promote initiation of egg deposition in a mating status dependent way. OvAbg/Cha neurons are required in exploration and egg deposition phases, though activation leads specifically to egg expulsion. Experiments with the OvAbg/Gad1 neurons show they participate in egg deposition. We further show a functional connection of OvAbg neurons with brain neurons. This study provides insight into the organization of neuronal circuits underlying complex motor behaviour.
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Affiliation(s)
| | - Miguel Gaspar
- Neuroscience Programme, Champalimaud Foundation, Lisbon, Portugal
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13
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Banse SA, Jarrett CM, Robinson KJ, Blue BW, Shaw EL, Phillips PC. The Egg-Counter: A novel microfluidic platform for characterization of Caenorhabditis elegans egg-laying. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555781. [PMID: 37732270 PMCID: PMC10508723 DOI: 10.1101/2023.09.01.555781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Reproduction is a fundamental process that shapes the demography of every living organism yet is often difficult to assess with high precision in animals that produce large numbers of offspring. Here, we present a novel microfluidic research platform for studying Caenorhabditis elegans' egg-laying. The platform provides higher throughput than traditional solid-media assays while providing a very high degree of temporal resolution. Additionally, the environmental control enabled by microfluidic animal husbandry allows for experimental perturbations difficult to achieve with solid-media assays. We demonstrate the platform's utility by characterizing C. elegans egg-laying behavior at two commonly used temperatures, 15 and 20°C. As expected, we observed a delayed onset of egg-laying at 15°C degrees, consistent with published temperature effects on development rate. Additionally, as seen in solid media studies, egg laying output was higher under the canonical 20°C conditions. While we validated the Egg-Counter with a study of temperature effects in wild-type animals, the platform is highly adaptable to any nematode egg-laying research where throughput or environmental control needs to be maximized without sacrificing temporal resolution.
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Affiliation(s)
- Stephen A. Banse
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Cody M. Jarrett
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Kristin J. Robinson
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Benjamin W. Blue
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Emily L. Shaw
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Patrick C. Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
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14
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Zhang L, Sun H, Grosse-Wilde E, Zhang L, Hansson BS, Dweck HKM. Cross-generation pheromonal communication drives Drosophila oviposition site choice. Curr Biol 2023; 33:2095-2103.e3. [PMID: 37098339 DOI: 10.1016/j.cub.2023.03.090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 01/09/2023] [Accepted: 03/31/2023] [Indexed: 04/27/2023]
Abstract
In a heterogeneous and changing environment, oviposition site selection strongly affects the survival and fitness of the offspring.1,2 Similarly, competition between larvae affects their prospects.3 However, little is known about the involvement of pheromones in regulating these processes.4,5,6,7,8 Here, we show that mated females of Drosophila melanogaster prefer to lay eggs on substrates containing extracts of conspecific larvae. After analyzing these extracts chemically, we test each compound in an oviposition assay and find that mated females display a dose-dependent preference to lay eggs on substrates spiked with (Z)-9-octadecenoic acid ethyl ester (OE). This egg-laying preference relies on gustatory receptor Gr32a and tarsal sensory neurons expressing this receptor. The concentration of OE also regulates larval place choice in a dose-dependent manner. Physiologically, OE activates female tarsal Gr32a+ neurons. In conclusion, our results reveal a cross-generation communication strategy essential for oviposition site selection and regulation of larval density.
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Affiliation(s)
- Liwei Zhang
- College of Grassland Science and Technology, China Agricultural University, Yuanmingyuan West Rd. 2, Beijing 100193, China; Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany.
| | - Huiwen Sun
- College of Grassland Science and Technology, China Agricultural University, Yuanmingyuan West Rd. 2, Beijing 100193, China
| | - Ewald Grosse-Wilde
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
| | - Long Zhang
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Gongye North Rd. 202, Jinan 250100, China
| | - Bill S Hansson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
| | - Hany K M Dweck
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
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15
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Benton R, Dahanukar A. Chemosensory Coding in Drosophila Single Sensilla. Cold Spring Harb Protoc 2023; 2023:107803-pdb.top. [PMID: 36446528 DOI: 10.1101/pdb.top107803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The chemical senses-smell and taste-detect and discriminate an enormous diversity of environmental stimuli and provide fascinating but challenging models to investigate how sensory cues are represented in the brain. Important stimulus-coding events occur in peripheral sensory neurons, which express specific combinations of chemosensory receptors with defined ligand-response profiles. These receptors convert ligand recognition into spatial and temporal patterns of neural activity that are transmitted to, and interpreted in, central brain regions. Drosophila melanogaster provides an attractive model to study chemosensory coding because it possesses relatively simple peripheral olfactory and gustatory systems that display many organizational parallels to those of vertebrates. Moreover, nearly all peripheral chemosensory neurons have been molecularly characterized and are accessible for physiological analysis, as they are exposed on the surface of sensory organs housed in specialized hairs called sensilla. Here, we briefly review anatomical, molecular, and physiological properties of adult Drosophila olfactory and gustatory systems and provide background to methods for electrophysiological recordings of ligand-evoked activity from different types of chemosensory sensilla.
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Affiliation(s)
- Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Anupama Dahanukar
- Department of Molecular, Cell & Systems Biology, University of California, Riverside, California 92521, USA
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16
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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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17
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Deere JU, Sarkissian AA, Yang M, Uttley HA, Martinez Santana N, Nguyen L, Ravi K, Devineni AV. Selective integration of diverse taste inputs within a single taste modality. eLife 2023; 12:e84856. [PMID: 36692370 PMCID: PMC9873257 DOI: 10.7554/elife.84856] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [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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18
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Wang W, Dweck HKM, Talross GJS, Zaidi A, Gendron JM, Carlson JR. Sugar sensation and mechanosensation in the egg-laying preference shift of Drosophila suzukii. eLife 2022; 11:e81703. [PMID: 36398882 PMCID: PMC9674340 DOI: 10.7554/elife.81703] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022] Open
Abstract
The agricultural pest Drosophila suzukii differs from most other Drosophila species in that it lays eggs in ripe, rather than overripe, fruit. Previously, we showed that changes in bitter taste sensation accompanied this adaptation (Dweck et al., 2021). Here, we show that D. suzukii has also undergone a variety of changes in sweet taste sensation. D. suzukii has a weaker preference than Drosophila melanogaster for laying eggs on substrates containing all three primary fruit sugars: sucrose, fructose, and glucose. Major subsets of D. suzukii taste sensilla have lost electrophysiological responses to sugars. Expression of several key sugar receptor genes is reduced in the taste organs of D. suzukii. By contrast, certain mechanosensory channel genes, including no mechanoreceptor potential C, are expressed at higher levels in the taste organs of D. suzukii, which has a higher preference for stiff substrates. Finally, we find that D. suzukii responds differently from D. melanogaster to combinations of sweet and mechanosensory cues. Thus, the two species differ in sweet sensation, mechanosensation, and their integration, which are all likely to contribute to the differences in their egg-laying preferences in nature.
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Affiliation(s)
- Wanyue Wang
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Hany KM Dweck
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Gaëlle JS Talross
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Ali Zaidi
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - Joshua M Gendron
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
| | - John R Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew HavenUnited States
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19
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Vijayan V, Wang Z, Chandra V, Chakravorty A, Li R, Sarbanes SL, Akhlaghpour H, Maimon G. An internal expectation guides Drosophila egg-laying decisions. SCIENCE ADVANCES 2022; 8:eabn3852. [PMID: 36306348 PMCID: PMC9616500 DOI: 10.1126/sciadv.abn3852] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
To better understand how animals make ethologically relevant decisions, we studied egg-laying substrate choice in Drosophila. We found that flies dynamically increase or decrease their egg-laying rates while exploring substrates so as to target eggs to the best, recently visited option. Visiting the best option typically yielded inhibition of egg laying on other substrates for many minutes. Our data support a model in which flies compare the current substrate's value with an internally constructed expectation on the value of available options to regulate the likelihood of laying an egg. We show that dopamine neuron activity is critical for learning and/or expressing this expectation, similar to its role in certain tasks in vertebrates. Integrating sensory experiences over minutes to generate an estimate of the quality of available options allows flies to use a dynamic reference point for judging the current substrate and might be a general way in which decisions are made.
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20
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Xiao S, Baik LS, Shang X, Carlson JR. Meeting a threat of the Anthropocene: Taste avoidance of metal ions by Drosophila. Proc Natl Acad Sci U S A 2022; 119:e2204238119. [PMID: 35700364 PMCID: PMC9231609 DOI: 10.1073/pnas.2204238119] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/06/2022] [Indexed: 11/18/2022] Open
Abstract
The Anthropocene Epoch poses a critical challenge for organisms: they must cope with new threats at a rapid rate. These threats include toxic chemical compounds released into the environment by human activities. Here, we examine elevated concentrations of heavy metal ions as an example of anthropogenic stressors. We find that the fruit fly Drosophila avoids nine metal ions when present at elevated concentrations that the flies experienced rarely, if ever, until the Anthropocene. We characterize the avoidance of feeding and egg laying on metal ions, and we identify receptors, neurons, and taste organs that contribute to this avoidance. Different subsets of taste receptors, including members of both Ir (Ionotropic receptor) and Gr (Gustatory receptor) families contribute to the avoidance of different metal ions. We find that metal ions activate certain bitter-sensing neurons and inhibit sugar-sensing neurons. Some behavioral responses are mediated largely through neurons of the pharynx. Feeding avoidance remains stable over 10 generations of exposure to copper and zinc ions. Some responses to metal ions are conserved across diverse dipteran species, including the mosquito Aedes albopictus. Our results suggest mechanisms that may be essential to insects as they face challenges from environmental changes in the Anthropocene.
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Affiliation(s)
- Shuke Xiao
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
| | - Lisa S. Baik
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
| | - Xueying Shang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
| | - John R. Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511
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21
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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: 2.0] [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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22
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Devineni AV, Deere JU, Sun B, Axel R. Individual bitter-sensing neurons in Drosophila exhibit both ON and OFF responses that influence synaptic plasticity. Curr Biol 2021; 31:5533-5546.e7. [PMID: 34731675 DOI: 10.1016/j.cub.2021.10.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 09/04/2021] [Accepted: 10/08/2021] [Indexed: 01/07/2023]
Abstract
The brain generates internal representations that translate sensory stimuli into appropriate behavior. In the taste system, different tastes activate distinct populations of sensory neurons. We investigated the temporal properties of taste responses in Drosophila and discovered that different types of taste sensory neurons show striking differences in their response dynamics. Strong responses to stimulus onset (ON responses) and offset (OFF responses) were observed in bitter-sensing neurons in the labellum, whereas bitter neurons in the leg and other classes of labellar taste neurons showed only an ON response. Individual labellar bitter neurons generate both ON and OFF responses through a cell-intrinsic mechanism that requires canonical bitter receptors. A single receptor complex likely generates both ON and OFF responses to a given bitter ligand. These ON and OFF responses in the periphery are propagated to dopaminergic neurons that mediate aversive learning, and the presence of the OFF response impacts synaptic plasticity when bitter is used as a reinforcement cue. These studies reveal previously unknown features of taste responses that impact neural circuit function and may be important for behavior. Moreover, these studies show that OFF responses can dramatically influence timing-based synaptic plasticity, which is thought to underlie associative learning.
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Affiliation(s)
- Anita V Devineni
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA.
| | - Julia U Deere
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA
| | - Bei Sun
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA
| | - Richard Axel
- Zuckerman Mind Brain Behavior Institute, Columbia University, 3227 Broadway, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
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23
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Shrestha B, Lee Y. Mechanisms of DEET gustation in Drosophila. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 131:103550. [PMID: 33549816 DOI: 10.1016/j.ibmb.2021.103550] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/31/2021] [Accepted: 01/31/2021] [Indexed: 06/12/2023]
Abstract
DEET is the most widely used active ingredient in insect repellents and offers protection against insect bites. We previously reported that DEET suppresses the feeding behavior of Drosophila, which is guided by gustatory receptors (GRs) in bitter-sensing gustatory receptor neurons. Here, we sought to identify new candidates using egg-laying assays. Upon screening all GR mutants, GR89a was identified as a potential DEET receptor. Gr89a mutants exhibited reduced oviposition avoidance, feeding avoidance, and electrophysiological responses compared to Gr32a, Gr33a, and Gr66a mutants. However, GR89a was found to modulate DEET avoidance, as demonstrated by genetic and RNA interference assays. Furthermore, we found that DEET ingestion severely affected larval and pupal development and survival, and therefore may act as an effective larvicide.
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Affiliation(s)
- Bhanu Shrestha
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea
| | - Youngseok Lee
- Department of Bio & Fermentation Convergence Technology, Kookmin University, Seoul, 02707, Republic of Korea; Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul, 02707, Republic of Korea.
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24
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Dweck HK, Talross GJ, Wang W, Carlson JR. Evolutionary shifts in taste coding in the fruit pest Drosophila suzukii. eLife 2021; 10:64317. [PMID: 33616529 PMCID: PMC7899650 DOI: 10.7554/elife.64317] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 01/23/2021] [Indexed: 01/17/2023] Open
Abstract
Although most Drosophila species lay eggs in overripe fruit, the agricultural pest Drosophila suzukii lays eggs in ripe fruit. We found that changes in bitter taste perception have accompanied this adaptation. We show that bitter-sensing mutants of Drosophila melanogaster undergo a shift in egg laying preference toward ripe fruit. D. suzukii has lost 20% of the bitter-sensing sensilla from the labellum, the major taste organ of the head. Physiological responses to various bitter compounds are lost. Responses to strawberry purées are lost from two classes of taste sensilla. Egg laying is not deterred by bitter compounds that deter other species. Profiling of labellar transcriptomes reveals reduced expression of several bitter Gr genes (gustatory receptors). These findings support a model in which bitter compounds in early ripening stages deter egg laying in most Drosophila species, but a loss of bitter response contributes to the adaptation of D. suzukii to ripe fruit. A new agricultural pest has recently emerged in the United States and Northern Europe. The invasive species is a type of fruit fly that normally lives in Southeast Asia called Drosophila suzukii (also known as the spotted wing Drosophila). This fly poses a threat to fruit crops – including strawberries, blueberries, cherries, peaches and grapes – because, while other fruit flies lay eggs in overripe fruit, D. suzukii lays eggs in ripe fruit, leading to agricultural losses. This shift in where fruit flies prefer to lay their eggs is related to changes in the senses of smell and touch, and taste could also play a role. Insects have evolved mechanisms that dissuade them from eating or laying eggs in plants with high levels of toxins, which taste bitter. If D. suzukii is less sensitive to bitter tastes than other flies, this could help explain why it lays eggs in just-ripe fruit, since the levels of certain bitter compounds are higher in the early stages of ripening than later on. To figure out if this is the case, Dweck et al. studied different species of fruit fly. Compared to Drosophila melanogaster (a fruit fly common in America and Europe that is regularly used in scientific studies), D. suzukii had fewer bitter taste receptor neurons on the major taste organ of the fly head. These receptor neurons were also less responsive to a variety of bitter compounds. Next, Dweck et al. tested whether D. melanogaster and D. suzukii showed different preferences for where to lay their eggs by offering them strawberry purées made from fruit at different ripening stages. In this experiment, D. suzukii preferred to lay its eggs on purées made from unripe or just-ripe strawberries, while D. melanogaster showed a preference for fermented (overripe) purée. Furthermore, when D. melanogaster flies were genetically modified so that they became less sensitive to bitter taste, they preferred to lay their eggs in ripe (rather than overripe) fruit, similar to D. suzukii. These results suggest that taste has a major role in the egg laying preferences of D. suzukii. Further research is needed to determine which bitter compounds influence egg-laying decisions in each species of fruit fly, and what receptors respond to these compounds. However, Dweck et al.’s results lay the groundwork for new approaches to reducing D. suzukii’s impact on agriculture.
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Affiliation(s)
- Hany Km Dweck
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
| | - Gaëlle Js Talross
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
| | - Wanyue Wang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
| | - John R Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
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25
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Chen YCD, Park SJ, Joseph RM, Ja WW, Dahanukar AA. Combinatorial Pharyngeal Taste Coding for Feeding Avoidance in Adult Drosophila. Cell Rep 2020; 29:961-973.e4. [PMID: 31644916 PMCID: PMC6860367 DOI: 10.1016/j.celrep.2019.09.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/18/2019] [Accepted: 09/12/2019] [Indexed: 01/05/2023] Open
Abstract
Taste drives appropriate food preference and intake. In Drosophila, taste neurons are housed in both external and internal organs, but the latter have been relatively underexplored. Here, we report that Poxn mutants with a minimal taste system of pharyngeal neurons can avoid many aversive tastants, including bitter compounds, acid, and salt, suggesting that pharyngeal taste is sufficient for rejecting intake of aversive compounds. Optogenetic activation of selected pharyngeal bitter neurons during feeding events elicits changes in feeding parameters that can suppress intake. Functional dissection experiments indicate that multiple classes of pharyngeal neurons are involved in achieving behavioral avoidance, by virtue of being inhibited or activated by aversive tastants. Tracing second-order pharyngeal circuits reveals two main relay centers for processing pharyngeal taste inputs. Together, our results suggest that the pharynx can control the ingestion of harmful compounds by integrating taste input from different classes of pharyngeal neurons. Chen et al. perform functional and behavioral experiments to study the roles of different subsets of pharyngeal neurons in governing food avoidance in flies. They find evidence that rejection of different categories of aversive compounds is dependent on distinct combinations of pharyngeal taste neurons.
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Affiliation(s)
- Yu-Chieh David Chen
- Interdepartmental Neuroscience Program, University of California, Riverside, CA 92521, USA
| | - Scarlet Jinhong Park
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA; Skaggs Graduate School, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Ryan Matthew Joseph
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA 92521, USA
| | - William W Ja
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA; Skaggs Graduate School, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Anupama Arun Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, CA 92521, USA; Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA 92521, USA.
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26
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Zhang L, Yu J, Guo X, Wei J, Liu T, Zhang W. Parallel Mechanosensory Pathways Direct Oviposition Decision-Making in Drosophila. Curr Biol 2020; 30:3075-3088.e4. [PMID: 32649914 DOI: 10.1016/j.cub.2020.05.076] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/09/2020] [Accepted: 05/22/2020] [Indexed: 10/23/2022]
Abstract
Female Drosophila choose their sites for oviposition with deliberation. Female flies employ sensitive chemosensory systems to evaluate chemical cues for egg-laying substrates, but how they determine the physical quality of an oviposition patch remains largely unexplored. Here we report that flies evaluate the stiffness of the substrate surface using sensory structures on their appendages. The TRPV family channel Nanchung is required for the detection of all stiffness ranges tested, whereas two other proteins, Inactive and DmPiezo, interact with Nanchung to sense certain spectral ranges of substrate stiffness differences. Furthermore, Tmc is critical for sensing subtle differences in substrate stiffness. The Tmc channel is expressed in distinct patterns on the labellum and legs and the mechanosensory inputs coordinate to direct the final decision making for egg laying. Our study thus reveals the machinery for deliberate egg-laying decision making in fruit flies to ensure optimal survival for their offspring.
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Affiliation(s)
- Liwei Zhang
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 100084, China.
| | - Jie Yu
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 100084, China
| | - Xuan Guo
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 100084, China
| | - Jianhuan Wei
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 100084, China
| | - Ting Liu
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 100084, China
| | - Wei Zhang
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research at Tsinghua, Tsinghua University, Beijing 100084, China.
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27
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Taste recognition through tarsal gustatory sensilla potentially important for host selection in leaf beetles (Coleoptera: Chrysomelidae). Sci Rep 2020; 10:4931. [PMID: 32188903 PMCID: PMC7080798 DOI: 10.1038/s41598-020-61935-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 03/05/2020] [Indexed: 11/25/2022] Open
Abstract
It is well known that Diptera and Lepidoptera can recognize tastes through their legs, which allows them to select suitable hosts. In Coleoptera, the largest insect order, however, the role of the legs in taste recognition to aid in host selection is unclear. In the present study, we investigated taste recognition through the legs of Chrysomelidae, Coleoptera. Through morphological observations, we found that all subfamilies of Chrysomelidae exhibit gustatory sensilla in the distal leg segment, i.e., the tarsus. In contrast, we did not find evidence of these sensilla in the species that we examined from four families of Coleoptera. We confirmed that different tastes, i.e., sweet, bitter, and leaf surface wax, were received through the tarsal sensilla of Chrysomelidae by recording the electrophysiological responses of the sensilla. Further, we found that Galerucella grisescens (Chrysomelidae) can respond to different tastes used in the electrophysiological tests using only their tarsi, whereas Henosepilachna vigintioctomaculata (Coccinellidae), lacking tarsal gustatory sensilla, did not exhibit similar responses. Our results suggest that although tarsal taste recognition is not common throughout Coleopteran species, it may be a common feature in Chrysomelidae, and tarsal gustation may play an important role in host selection in this family.
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28
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Chin SG, Maguire SE, Huoviala P, Jefferis GSXE, Potter CJ. Olfactory Neurons and Brain Centers Directing Oviposition Decisions in Drosophila. Cell Rep 2020; 24:1667-1678. [PMID: 30089274 PMCID: PMC6290906 DOI: 10.1016/j.celrep.2018.07.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 04/30/2018] [Accepted: 07/04/2018] [Indexed: 01/19/2023] Open
Abstract
The sense of smell influences many behaviors, yet how odors are represented in the brain remains unclear. A major challenge to studying olfaction is the lack of methods allowing activation of specific types of olfactory neurons in an ethologically relevant setting. To address this, we developed a genetic method in Drosophila called olfactogenetics in which a narrowly tuned odorant receptor, Or56a, is ectopically expressed in different olfactory neuron types. Stimulation with geosmin (the only known Or56a ligand) in an Or56a mutant background leads to specific activation of only target olfactory neuron types. We used this approach to identify olfactory sensory neurons (OSNs) that directly guide oviposition decisions. We identify 5 OSN-types (Or71a, Or47b, Or49a, Or67b, and Or7a) that, when activated alone, suppress oviposition. Projection neurons partnering with these OSNs share a region of innervation in the lateral horn, suggesting that oviposition site selection might be encoded in this brain region.
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Affiliation(s)
- Sonia G Chin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Sarah E Maguire
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Paavo Huoviala
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 OQH, UK
| | - Gregory S X E Jefferis
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 OQH, UK
| | - Christopher J Potter
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 855 N. Wolfe Street, Baltimore, MD 21205, USA.
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29
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Dweck HKM, Carlson JR. Molecular Logic and Evolution of Bitter Taste in Drosophila. Curr Biol 2019; 30:17-30.e3. [PMID: 31839451 DOI: 10.1016/j.cub.2019.11.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/13/2019] [Accepted: 11/01/2019] [Indexed: 01/05/2023]
Abstract
Taste systems detect a vast diversity of toxins, which are perceived as bitter. When a species adapts to a new environment, its taste system must adapt to detect new death threats. We deleted each of six commonly expressed bitter gustatory receptors (Grs) from Drosophila melanogaster. Systematic analysis revealed that requirements for these Grs differed for the same tastant in different neurons and for different tastants in the same neuron. Responses to some tastants in some neurons required four Grs, including Gr39a. Deletions also produced increased or novel responses, supporting a model of Gr-Gr inhibitory interactions. Coexpression of four Grs conferred several bitter responses to a sugar neuron. We then examined bitter coding in three other Drosophila species. We found major evolutionary shifts. One shift depended on the concerted activity of seven Grs. This work shows how the complex logic of bitter coding provides the capacity to detect innumerable hazards and the flexibility to adapt to new ones.
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Affiliation(s)
- Hany K M Dweck
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - John R Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
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30
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Chen W, Chen L, Li D, Kang K, Liu K, Yue L, Zhang W. Two alternative splicing variants of a sugar gustatory receptor modulate fecundity through different signalling pathways in the brown planthopper, Nilaparvata lugens. JOURNAL OF INSECT PHYSIOLOGY 2019; 119:103966. [PMID: 31626759 DOI: 10.1016/j.jinsphys.2019.103966] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 10/10/2019] [Accepted: 10/10/2019] [Indexed: 06/10/2023]
Abstract
Insect gustatory receptors play crucial roles in multiple physiological behaviours. Although the alternative splicing of some gustatory receptors has been observed in insect species, differences in their ligands and functions have rarely been reported. Here, we cloned NlGr10a and NlGr10b, two alternative splicing variants of a sugar gustatory receptor gene in the brown planthopper (BPH), Nilaparvata lugens (Stål), and found that their ligands were different by calcium imaging assay. The ligands of NlGr10a were fructose and cellobiose, and the ligand of NlGr10b was arabinose. Subsequently, the RNAi results showed that knockdown of both splicing variants decreased the number of eggs laid by BPH females, and the egg hatching rate after knockdown of NlGr10a was significantly lower than that after knockdown of NlGr10b. Furthermore, NlGr10a promoted the fecundity of BPH through the AMPK- and AKT-NlVg/NlVgR signalling pathways, whereas NlGr10b promoted the fecundity only through the AMPK- and AKT-NlVg signalling pathways. These findings broaden our understanding of the difference in the ligands and functions of alternative splicing variants of gustatory receptors in insects.
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Affiliation(s)
- Weiwen Chen
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Li'e Chen
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Dan Li
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Kui Kang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Kai Liu
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Lei Yue
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wenqing Zhang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
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31
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Gowri V, Dion E, Viswanath A, Piel FM, Monteiro A. Transgenerational inheritance of learned preferences for novel host plant odors inBicyclus anynanabutterflies. Evolution 2019; 73:2401-2414. [DOI: 10.1111/evo.13861] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 09/21/2019] [Indexed: 12/31/2022]
Affiliation(s)
- V. Gowri
- Department of Biological SciencesNational University of Singapore 14 Science Drive 4 117543 Singapore
| | - Emilie Dion
- Department of Biological SciencesNational University of Singapore 14 Science Drive 4 117543 Singapore
| | - Athmaja Viswanath
- Department of Biological SciencesNational University of Singapore 14 Science Drive 4 117543 Singapore
| | - Florence Monteiro Piel
- Department of Biological SciencesNational University of Singapore 14 Science Drive 4 117543 Singapore
| | - Antónia Monteiro
- Department of Biological SciencesNational University of Singapore 14 Science Drive 4 117543 Singapore
- Yale‐NUS‐College 6 College Avenue East 138614 Singapore
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32
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Molecular control limiting sensitivity of sweet taste neurons in Drosophila. Proc Natl Acad Sci U S A 2019; 116:20158-20168. [PMID: 31527261 DOI: 10.1073/pnas.1911583116] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
To assess the biological value of environmental stimuli, animals' sensory systems must accurately decode both the identities and the intensities of these stimuli. While much is known about the mechanism by which sensory neurons detect the identities of stimuli, less is known about the mechanism that controls how sensory neurons respond appropriately to different intensities of stimuli. The ionotropic receptor IR76b has been shown to be expressed in different Drosophila chemosensory neurons for sensing a variety of chemicals. Here, we show that IR76b plays an unexpected role in lowering the sensitivity of Drosophila sweet taste neurons. First, IR76b mutants exhibited clear behavioral responses to sucrose and acetic acid (AA) at concentrations that were too low to trigger observable behavioral responses from WT animals. Second, IR76b is expressed in many sweet neurons on the labellum, and these neurons responded to both sucrose and AA. Removing IR76b from the sweet neurons increased their neuronal responses as well as animals' behavioral responses to sucrose and AA. Conversely, overexpressing IR76b in the sweet neurons decreased their neuronal as well as animals' behavioral responses to sucrose and AA. Last, IR76b's response-lowering ability has specificity: IR76b mutants and WT showed comparable responses to capsaicin when the mammalian capsaicin receptor VR1 was ectopically expressed in their sweet neurons. Our findings suggest that sensitivity of Drosophila sweet neurons to their endogenous ligands is actively limited by IR76b and uncover a potential molecular target by which contexts can modulate sensitivity of sweet neurons.
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33
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Wu SF, Ja YL, Zhang YJ, Yang CH. Sweet neurons inhibit texture discrimination by signaling TMC-expressing mechanosensitive neurons in Drosophila. eLife 2019; 8:46165. [PMID: 31184585 PMCID: PMC6559806 DOI: 10.7554/elife.46165] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 05/30/2019] [Indexed: 11/13/2022] Open
Abstract
Integration of stimuli of different modalities is an important but incompletely understood process during decision making. Here, we show that Drosophila are capable of integrating mechanosensory and chemosensory information of choice options when deciding where to deposit their eggs. Specifically, females switch from preferring the softer option for egg-laying when both options are sugar free to being indifferent between them when both contain sucrose. Such sucrose-induced indifference between options of different hardness requires functional sweet neurons, and, curiously, the Transmembrane Channel-like (TMC)-expressing mechanosensitive neurons that have been previously shown to promote discrimination of substrate hardness during feeding. Further, axons of sweet neurons directly contact axons of TMC-expressing neurons in the brain and stimulation of sweet neurons increases Ca2+ influx into axons of TMC-expressing neurons. These results uncover one mechanism by which Drosophila integrate taste and tactile information when deciding where to deposit their eggs and reveal that TMC-expressing neurons play opposing roles in hardness discrimination in two different decisions.
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Affiliation(s)
- Shun-Fan Wu
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.,Department of Neurobiology, Duke University, Durham, United States
| | - Ya-Long Ja
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yi-Jie Zhang
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Chung-Hui Yang
- Department of Neurobiology, Duke University, Durham, United States
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34
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Cury KM, Prud'homme B, Gompel N. A short guide to insect oviposition: when, where and how to lay an egg. J Neurogenet 2019; 33:75-89. [PMID: 31164023 DOI: 10.1080/01677063.2019.1586898] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Egg-laying behavior is one of the most important aspects of female behavior, and has a profound impact on the fitness of a species. As such, it is controlled by several layers of regulation. Here, we review recent advances in our understanding of insect neural circuits that control when, where and how to lay an egg. We also outline outstanding open questions about the control of egg-laying decisions, and speculate on the possible neural underpinnings that can drive the diversification of oviposition behaviors through evolution.
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Affiliation(s)
- Kevin M Cury
- a Department of Neuroscience and the Mortimer B. Zuckerman Mind Brain Behavior Institute , Columbia University , New York , NY , USA
| | - Benjamin Prud'homme
- b Aix Marseille Université, CNRS , Institut de Biologie du Développement de Marseille (IBDM) , Marseille , France
| | - Nicolas Gompel
- c Fakultät für Biologie, Biozentrum , Ludwig-Maximilians Universität München , Munich , Germany
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35
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Bräcker LB, Schmid CA, Bolini VA, Holz CA, Prud'homme B, Sirota A, Gompel N. Quantitative and Discrete Evolutionary Changes in the Egg-Laying Behavior of Single Drosophila Females. Front Behav Neurosci 2019; 13:118. [PMID: 31191270 PMCID: PMC6549446 DOI: 10.3389/fnbeh.2019.00118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/16/2019] [Indexed: 12/22/2022] Open
Abstract
How a nervous system assembles and coordinates a suite of elementary behavioral steps into a complex behavior is not well understood. While often presented as a stereotyped sequence of events, even extensively studied behaviors such as fly courtship are rarely a strict repetition of the same steps in a predetermined sequence in time. We are focusing on oviposition, the act of laying an egg, in flies of the genus Drosophila to describe the elementary behavioral steps or microbehaviors that a single female fly undertakes prior to and during egg laying. We have analyzed the hierarchy and relationships in time of these microbehaviors in three closely related Drosophila species with divergent egg-laying preferences and uncovered cryptic differences in their behavioral patterns. Using high-speed imaging, we quantified in depth the oviposition behavior of single females of Drosophila suzukii, Drosophila biarmipes and Drosophila melanogaster in a novel behavioral assay. By computing transitions between microbehaviors, we identified a common ethogram structure underlying oviposition of all three species. Quantifying parameters such as relative time spent on a microbehavior and its average duration, however, revealed clear differences between species. In addition, we examined the temporal dynamics and probability of transitions to different microbehaviors relative to a central event of oviposition, ovipositor contact. Although the quantitative analysis highlights behavioral variability across flies, it reveals some interesting trends for each species in the mode of substrate sampling, as well as possible evolutionary differences. Larger datasets derived from automated video annotation will overcome this paucity of data in the future, and use the same framework to reappraise these observed differences. Our study reveals a common architecture to the oviposition ethogram of three Drosophila species, indicating its ancestral state. It also indicates that Drosophila suzukii’s behavior departs quantitatively and qualitatively from that of the outgroup species, in line with its known divergent ethology. Together, our results illustrate how a global shift in ethology breaks down in the quantitative reorganization of the elementary steps underlying a complex behavior.
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Affiliation(s)
- Lasse B Bräcker
- Fakultät für Biologie, Biozentrum, Ludwig-Maximilians Universität München, Munich, Germany
| | - Christian A Schmid
- Fakultät für Biologie, Biozentrum, Ludwig-Maximilians Universität München, Munich, Germany
| | - Verena A Bolini
- Fakultät für Biologie, Biozentrum, Ludwig-Maximilians Universität München, Munich, Germany
| | - Claudia A Holz
- Fakultät für Biologie, Biozentrum, Ludwig-Maximilians Universität München, Munich, Germany
| | - Benjamin Prud'homme
- Aix-Marseille Université, CNRS, IBDM, Institut de Biologie du Développement de Marseille, Campus de Luminy Case 907, Marseille, France
| | - Anton Sirota
- Bernstein Center for Computational Neuroscience Munich, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Nicolas Gompel
- Fakultät für Biologie, Biozentrum, Ludwig-Maximilians Universität München, Munich, Germany
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36
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Kang K, Yang P, Chen LE, Pang R, Yu LJ, Zhou WW, Zhu ZR, Zhang WQ. Identification of putative fecundity-related gustatory receptor genes in the brown planthopper Nilaparvata lugens. BMC Genomics 2018; 19:970. [PMID: 30587129 PMCID: PMC6307266 DOI: 10.1186/s12864-018-5391-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 12/18/2018] [Indexed: 11/25/2022] Open
Abstract
Background The insect gustatory system plays a central role in the regulation of multiple physiological behaviors and the co-evolution between insects and their hosts. The gustatory receptors (Gr) are important to allow insects to sense their environment. It is critical to the selection of foods, mates and oviposition sites of insects. In this study, the Gr family genes of the brown planthopper (BPH) Nilaparvata lugens Stål (Hemiptera: Delphacidae) were identified and analyzed, and their potential relationship to the fecundity of BPH was explored by RNA interference (RNAi). Results We identified 32 putative Gr genes by analyzing transcriptome and genome data from BPH. Most of these Gr proteins have the typical structure of seven transmembrane domains. The BPH Gr genes (NlGrs) were expressed in virtually all tissues and stages, whilst higher transcript accumulations were found in adult stages and in the midguts of females. Based on the phylogenic analysis, we classified NlGrs into five potential categories, including 2 sugar receptors, 2 Gr43a-like receptors, 7 CO2 receptors, 5 bitter receptors and 13 NlGrs with unknown functions. Moreover, we found that 10 NlGrs have at least two alternative splicing variants, and obtained alternative splicing isoforms of 5 NlGrs. Finally, RNAi of 29 NlGrs showed that 27 of them are related to the transcript levels of two fecundity related genes vitellogenin and vitellogenin receptor. Conclusions We found 32 Gr genes in BPH, among which at least 27 are required for normal expression of fecundity markers of this insect pest. These findings provide the basis for the functional study of Grs and the exploration of potential genes involved in the monophagous character of BPH. Electronic supplementary material The online version of this article (10.1186/s12864-018-5391-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kui Kang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China
| | - Pan Yang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China
| | - Li-E Chen
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China
| | - Rui Pang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China
| | - Lu-Jun Yu
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China
| | - Wen-Wu Zhou
- State Key Laboratory of Rice Biology, Institute of Insect Sciences, Zhejiang University, Hangzhou, 310029, Zhejiang, China
| | - Zeng-Rong Zhu
- State Key Laboratory of Rice Biology, Institute of Insect Sciences, Zhejiang University, Hangzhou, 310029, Zhejiang, China
| | - Wen-Qing Zhang
- State Key Laboratory of Biocontrol and School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China.
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37
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Chen YCD, Park SJ, Ja WW, Dahanukar A. Using Pox-Neuro ( Poxn) Mutants in Drosophila Gustation Research: A Double-Edged Sword. Front Cell Neurosci 2018; 12:382. [PMID: 30405359 PMCID: PMC6207628 DOI: 10.3389/fncel.2018.00382] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 10/08/2018] [Indexed: 12/21/2022] Open
Abstract
In Drosophila, Pox-neuro (Poxn) is a member of the Paired box (Pax) gene family that encodes transcription factors with characteristic paired DNA-binding domains. During embryonic development, Poxn is expressed in sensory organ precursor (SOP) cells of poly-innervated external sensory (p-es) organs and is important for specifying p-es organ identity (chemosensory) as opposed to mono-innervated external sensory (m-es) organs (mechanosensory). In Poxn mutants, there is a transformation of chemosensory bristles into mechanosensory bristles. As a result, these mutants have often been considered to be entirely taste-blind, and researchers have used them in this capacity to investigate physiological and behavioral functions that act in a taste-independent manner. However, recent studies show that only external taste bristles are transformed in Poxn mutants whereas all internal pharyngeal taste neurons remain intact, raising concerns about interpretations of experimental results using Poxn mutants as taste-blind flies. In this review, we summarize the value of Poxn mutants in advancing our knowledge of taste-enriched genes and feeding behaviors, and encourage revisiting some of the conclusions about taste-independent nutrient-sensing mechanisms derived from these mutants. Lastly, we highlight that Poxn mutant flies remain a valuable tool for probing the function of the relatively understudied pharyngeal taste neurons in sensing meal properties and regulating feeding behaviors.
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Affiliation(s)
- Yu-Chieh David Chen
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, CA, United States
| | - Scarlet Jinhong Park
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, United States
| | - William W Ja
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, United States
| | - Anupama Dahanukar
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, CA, United States.,Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA, United States
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38
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Molecular and Cellular Organization of Taste Neurons in Adult Drosophila Pharynx. Cell Rep 2018; 21:2978-2991. [PMID: 29212040 DOI: 10.1016/j.celrep.2017.11.041] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 10/18/2017] [Accepted: 11/10/2017] [Indexed: 02/04/2023] Open
Abstract
The Drosophila pharyngeal taste organs are poorly characterized despite their location at important sites for monitoring food quality. Functional analysis of pharyngeal neurons has been hindered by the paucity of molecular tools to manipulate them, as well as their relative inaccessibility for neurophysiological investigations. Here, we generate receptor-to-neuron maps of all three pharyngeal taste organs by performing a comprehensive chemoreceptor-GAL4/LexA expression analysis. The organization of pharyngeal neurons reveals similarities and distinctions in receptor repertoires and neuronal groupings compared to external taste neurons. We validate the mapping results by pinpointing a single pharyngeal neuron required for feeding avoidance of L-canavanine. Inducible activation of pharyngeal taste neurons reveals functional differences between external and internal taste neurons and functional subdivision within pharyngeal sweet neurons. Our results provide roadmaps of pharyngeal taste organs in an insect model system for probing the role of these understudied neurons in controlling feeding behaviors.
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39
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Dore AA, McDowall L, Rouse J, Bretman A, Gage MJG, Chapman T. The role of complex cues in social and reproductive plasticity. Behav Ecol Sociobiol 2018; 72:124. [PMID: 30100665 PMCID: PMC6060796 DOI: 10.1007/s00265-018-2539-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 06/20/2018] [Accepted: 06/22/2018] [Indexed: 01/13/2023]
Abstract
Phenotypic plasticity can be a key determinant of fitness. The degree to which the expression of plasticity is adaptive relies upon the accuracy with which information about the state of the environment is integrated. This step might be particularly beneficial when environments, e.g. the social and sexual context, change rapidly. Fluctuating temporal dynamics could increase the difficulty of determining the appropriate level of expression of a plastic response. In this review, we suggest that new insights into plastic responses to the social and sexual environment (social and reproductive plasticity) may be gained by examining the role of complex cues (those comprising multiple, distinct sensory components). Such cues can enable individuals to more accurately monitor their environment in order to respond adaptively to it across the whole life course. We briefly review the hypotheses for the evolution of complex cues and then adapt these ideas to the context of social and sexual plasticity. We propose that the ability to perceive complex cues can facilitate plasticity, increase the associated fitness benefits and decrease the risk of costly 'mismatches' between phenotype and environment by (i) increasing the robustness of information gained from highly variable environments, (ii) fine-tuning responses by using multiple strands of information and (iii) reducing time lags in adaptive responses. We conclude by outlining areas for future research that will help to determine the interplay between complex cues and plasticity.
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Affiliation(s)
- Alice A. Dore
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ UK
| | - Laurin McDowall
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK
| | - James Rouse
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK
| | - Amanda Bretman
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK
| | - Matthew J. G. Gage
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ UK
| | - Tracey Chapman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ UK
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40
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Deciphering Drosophila female innate behaviors. Curr Opin Neurobiol 2018; 52:139-148. [PMID: 29940518 DOI: 10.1016/j.conb.2018.06.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/09/2018] [Indexed: 01/08/2023]
Abstract
Innate responses are often sexually dimorphic. Studies of female specific behaviors have remained niche, but the focus is changing as illustrated by the recent progress in understanding the female courtship responses and egg-laying decisions. In this review, we will cover our current knowledge about female behaviors in these two specific contexts. Recent studies elucidate on how females process the courtship song. They also show that egg-laying decisions are extremely complex, requiring the assessment of food, microbial, predator and social cues. Study of female responses will improve our understanding of how a nervous system processes different challenges.
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41
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Evolutionary compromises to metabolic toxins: Ammonia and urea tolerance in Drosophila suzukii and Drosophila melanogaster. Physiol Behav 2018; 191:146-154. [PMID: 29679661 DOI: 10.1016/j.physbeh.2018.04.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 04/06/2018] [Accepted: 04/15/2018] [Indexed: 01/19/2023]
Abstract
The invasive pest Drosophila suzukii has evolved morphological and behavioural adaptations to lay eggs under the skin of fresh fruits. This results in severe damage to a wide range of small fruits. Drosophila suzukii females typically lay few eggs per fruit, preferring healthy fruits. Hence, larvae are exposed to a reduced amount of nitrogenous waste. Differently, the innocuous Drosophila melanogaster lays eggs on fermented fruits already infested by conspecifics, with larvae developing in a crowded environment with the accumulation of nitrogenous waste such as ammonia and urea. These compounds derive from nitrogen metabolism, protein degradation, and amino acids catabolism and are relatively toxic at high concentrations in an organism. The observed differences in oviposition site and larval ecological niche suggest that these species might differ in behavioural and physiological mechanisms used to cope with nitrogenous waste. We investigated how different concentrations of ammonia and urea affect oviposition and larval development in both species. Females and larvae of D. suzukii showed greater susceptibility to high concentrations of both compounds, with a dramatic decrease in the number of eggs laid and egg viability. Moreover, we tested the chemotactic response of third instar larvae to high concentrations of the compounds. Interestingly, ammonia resulted in a repulsive behaviour in respect of the control and urea groups. To better understand the pathways underlying these differences, we evaluated the effect on ornithine aminotransferase and glutathione-S-transferase, two enzymes involved in nitrogen metabolism and stress response that are expressed during larval development. Both ammonia and urea significantly reduced the expression of these enzymes in D. suzukii compared to D. melanogaster. This shows how the ecological shift of D. suzukii to fresh fruit is accompanied by less efficient detoxifying and excretory mechanisms, with important implications for evolutionary biology and applied research. Our data suggest that the ecological shift of D. suzukii to fresh fruit as oviposition substrate is accompanied by a reduced tolerance to metabolic toxins during larval development.
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42
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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: 1.4] [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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43
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Billeter JC, Wolfner MF. Chemical Cues that Guide Female Reproduction in Drosophila melanogaster. J Chem Ecol 2018; 44:750-769. [PMID: 29557077 DOI: 10.1007/s10886-018-0947-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 02/21/2018] [Accepted: 03/13/2018] [Indexed: 01/05/2023]
Abstract
Chemicals released into the environment by food, predators and conspecifics play critical roles in Drosophila reproduction. Females and males live in an environment full of smells, whose molecules communicate to them the availability of food, potential mates, competitors or predators. Volatile chemicals derived from fruit, yeast growing on the fruit, and flies already present on the fruit attract Drosophila, concentrating flies at food sites, where they will also mate. Species-specific cuticular hydrocarbons displayed on female Drosophila as they mature are sensed by males and act as pheromones to stimulate mating by conspecific males and inhibit heterospecific mating. The pheromonal profile of a female is also responsive to her nutritional environment, providing an honest signal of her fertility potential. After mating, cuticular and semen hydrocarbons transferred by the male change the female's chemical profile. These molecules make the female less attractive to other males, thus protecting her mate's sperm investment. Females have evolved the capacity to counteract this inhibition by ejecting the semen hydrocarbon (along with the rest of the remaining ejaculate) a few hours after mating. Although this ejection can temporarily restore the female's attractiveness, shortly thereafter another male pheromone, a seminal peptide, decreases the female's propensity to re-mate, thus continuing to protect the male's investment. Females use olfaction and taste sensing to select optimal egg-laying sites, integrating cues for the availability of food for her offspring, and the presence of other flies and of harmful species. We argue that taking into account evolutionary considerations such as sexual conflict, and the ecological conditions in which flies live, is helpful in understanding the role of highly species-specific pheromones and blends thereof, as well as an individual's response to the chemical cues in its environment.
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Affiliation(s)
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA.
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44
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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: 69] [Impact Index Per Article: 9.9] [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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45
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Sensory mutations in Drosophila melanogaster influence associational effects between resources during oviposition. Sci Rep 2017; 7:9352. [PMID: 28839208 PMCID: PMC5570953 DOI: 10.1038/s41598-017-09728-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/28/2017] [Indexed: 11/26/2022] Open
Abstract
Neighboring resources can affect insect oviposition behavior when the complexity of sensory information obscures information about host resource availability in heterogeneous resource patches. These effects are referred to as associational effects and are hypothesized to occur through constraints in the sensory processing of the insect during host search, resulting into suboptimal resource use. Because the possibilities to study these constraints on naturally occurring animals are limited, we instead used sensory mutants of Drosophila melanogaster to determine the importance of sensory information in the occurrence of associational effects. We found that oviposition was mainly governed by non-volatile chemical cues and less by volatile cues. Moreover, the loss of gustatory sensilla resulted in random resource selection and eliminated associational effects. In conclusion, our study shows that associational effects do not necessarily depend on constraints in the sensory evaluation of resource quality, but may instead be a direct consequence of distinctive selection behavior between different resources at small scales.
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46
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Joseph RM, Sun JS, Tam E, Carlson JR. A receptor and neuron that activate a circuit limiting sucrose consumption. eLife 2017; 6. [PMID: 28332980 PMCID: PMC5388533 DOI: 10.7554/elife.24992] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 03/19/2017] [Indexed: 11/23/2022] Open
Abstract
The neural control of sugar consumption is critical for normal metabolism. In contrast to sugar-sensing taste neurons that promote consumption, we identify a taste neuron that limits sucrose consumption in Drosophila. Silencing of the neuron increases sucrose feeding; optogenetic activation decreases it. The feeding inhibition depends on the IR60b receptor, as shown by behavioral analysis and Ca2+ imaging of an IR60b mutant. The IR60b phenotype shows a high degree of chemical specificity when tested with a broad panel of tastants. An automated analysis of feeding behavior in freely moving flies shows that IR60b limits the duration of individual feeding bouts. This receptor and neuron provide the molecular and cellular underpinnings of a new element in the circuit logic of feeding regulation. We propose a dynamic model in which sucrose acts via IR60b to activate a circuit that inhibits feeding and prevents overconsumption. DOI:http://dx.doi.org/10.7554/eLife.24992.001 All animals – from the fruit fly to mammals like humans – must control their dietary intake of nutrients to survive and stay healthy. Taste receptors that sense high-calorie sugars are essential to this process. Typically, when food tastes sweet, it signals that the food contains nutrients and promotes consumption. However, eating too much sugar can be detrimental because the animal wastes time and energy eating food that it does not need, and could eventually lead to obesity and other metabolic diseases. This raised the question: are there any taste receptors that, once they detect sugars, cause animals to eat less? Joseph et al. worked with the fruit fly Drosophila melanogaster and identified one such taste receptor called IR60b. The experiments showed that this taste receptor responds selectively to sucrose (a high-calorie sugar), and that it activates nerve cells that cause fruit flies to eat less food, rather than more. When the receptor was experimentally inactivated, the fruit flies ate for longer and ate too much sucrose. This indicates that the flies need this receptor to control their sugar intake. A next step will be to see if mammals similarly use sweet-sensing taste receptors to limit the amount of food they eat. A better insight into how mammals can control what they eat could provide a deeper understanding of how to tackle major health issues, such as obesity, in humans. DOI:http://dx.doi.org/10.7554/eLife.24992.002
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Affiliation(s)
- Ryan M Joseph
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
| | - Jennifer S Sun
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
| | - Edric Tam
- Department of Biomedical Engineering, Yale University, New Haven, United States
| | - John R Carlson
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
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47
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A Bitter Taste of the Sun Makes Egg-Laying Flies Run. Genetics 2017; 205:467-469. [PMID: 28154195 DOI: 10.1534/genetics.116.196352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 11/20/2016] [Indexed: 11/18/2022] Open
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48
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Sumethasorn M, Turner TL. Oviposition preferences for ethanol depend on spatial arrangement and differ dramatically among closely related Drosophila species. Biol Open 2016; 5:1642-1647. [PMID: 27694106 PMCID: PMC5155530 DOI: 10.1242/bio.019380] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Recent work on the model fly Drosophila melanogaster has reported inconsistencies in their preference for laying eggs on intermediate concentrations of ethanol. In this study, we resolve this discrepancy by showing that this species strongly prefers ovipositing on ethanol when it is close to a non-ethanol substrate, but strongly avoids ethanol when options are farther apart. We also show fluidity of these behaviors among other Drosophila species: D. melanogaster is more responsive to ethanol than close relatives in that it prefers ethanol more than other species in the close-proximity case, but avoids ethanol more than other species in the distant case. In the close-proximity scenario, the more ethanol-tolerant species generally prefer ethanol more, with the exception of the island endemic D. santomea. This species has the lowest tolerance in the clade, but behaves like D. melanogaster. We speculate that this could be an adaptation to protect eggs from parasites or predators such as parasitoid wasps, as larvae migrate to non-toxic substrates after hatching. These natural differences among species are an excellent opportunity to study how genes and brains evolve to alter ethanol preferences, and provide an interesting model for genetic variation in preferences in other organisms, including humans. Summary:Drosophila species make dramatically different egg-laying decisions depending on ethanol concentration and the distances between options. Surprisingly, we find that the species with the lowest ethanol tolerance prefers ethanol the most.
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Affiliation(s)
- Matt Sumethasorn
- Ecological Biology, 9620 UC Santa Barbara, Santa Barbara, CA 93106-00
| | - Thomas L Turner
- Ecological Biology, 9620 UC Santa Barbara, Santa Barbara, CA 93106-00
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49
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Soldano A, Alpizar YA, Boonen B, Franco L, López-Requena A, Liu G, Mora N, Yaksi E, Voets T, Vennekens R, Hassan BA, Talavera K. Gustatory-mediated avoidance of bacterial lipopolysaccharides via TRPA1 activation in Drosophila. eLife 2016; 5. [PMID: 27296646 PMCID: PMC4907694 DOI: 10.7554/elife.13133] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 05/12/2016] [Indexed: 11/13/2022] Open
Abstract
Detecting pathogens and mounting immune responses upon infection is crucial for animal health. However, these responses come at a high metabolic price (McKean and Lazzaro, 2011, Kominsky et al., 2010), and avoiding pathogens before infection may be advantageous. The bacterial endotoxins lipopolysaccharides (LPS) are important immune system infection cues (Abbas et al., 2014), but it remains unknown whether animals possess sensory mechanisms to detect them prior to infection. Here we show that Drosophila melanogaster display strong aversive responses to LPS and that gustatory neurons expressing Gr66a bitter receptors mediate avoidance of LPS in feeding and egg laying assays. We found the expression of the chemosensory cation channel dTRPA1 in these cells to be necessary and sufficient for LPS avoidance. Furthermore, LPS stimulates Drosophila neurons in a TRPA1-dependent manner and activates exogenous dTRPA1 channels in human cells. Our findings demonstrate that flies detect bacterial endotoxins via a gustatory pathway through TRPA1 activation as conserved molecular mechanism. DOI:http://dx.doi.org/10.7554/eLife.13133.001 An immune system can fight bacterial infections, ensuring an animal’s health and survival. However, mounting an immune response to a bacterial infection requires a lot of energy. It also can be potentially dangerous if the immune system becomes too active. Therefore, avoiding bacteria and not getting infected to begin with may be a better strategy to stay healthy. Fruit flies, like humans, can detect dangerous substances in the environment via their sense of smell, but it is not known whether they also detect disease-causing organisms through their sense of taste. Bacterial molecules called lipopolysaccharides (LPS) can alert the immune system to the presence of dangerous bacteria. Previous studies have found that when flies get in contact with LPS they begin cleaning themselves, which might help prevent infection. However it was not clear how the flies actually detected the LPS. Now, Soldano et al. show that fruit flies can taste LPS and avoid eating or laying eggs on food contaminated with LPS and bacteria. A series of experiments showed that when a fly tastes LPS it stimulates bitter-sensing neurons in the fly’s mouth and throat. The experiments also revealed that the protein that activates these neurons in response to LPS is the same protein that acts in humans as detector of pungent chemicals contained in ordinary food items like mustard, garlic and wasabi. This suggests this protein, called TRPA1, is part of a key survival mechanism that has been preserved in many species throughout evolution. Soldano et al. showed that a fly’s senses and nervous system are actively involved in protecting it from bacterial infection. This is particularly important to flies, because unlike humans they don’t develop resistance to future infections with the same bacteria. Future studies are needed to determine if flies use their sense of taste to detect other chemicals that are signs of infections. Additionally, studies are needed to determine if the activated bitter-sensing nerves alert the fly’s immune system to a potential infection. DOI:http://dx.doi.org/10.7554/eLife.13133.002
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Affiliation(s)
- Alessia Soldano
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Yeranddy A Alpizar
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Brett Boonen
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Luis Franco
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium.,Neuroelectronics Research Flanders, Leuven, Belgium
| | - Alejandro López-Requena
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Guangda Liu
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Natalia Mora
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Emre Yaksi
- Neuroelectronics Research Flanders, Leuven, Belgium.,Kavli Institute for Systems Neuroscience and Centre for Neural Computation, NTNU, Trondheim, Norway
| | - Thomas Voets
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Rudi Vennekens
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Bassem A Hassan
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium.,Institut du Cerveau et de la Moelle Epinière, Hôpital Pitié-Salpétrière, Paris, France.,Ecole Doctorale Cerveau Cognition Comportement, Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Karel Talavera
- Laboratory of Ion Channel Research and TRP Research Platform Leuven, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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50
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Poudel S, Lee Y. Gustatory Receptors Required for Avoiding the Toxic Compound Coumarin in Drosophila melanogaster. Mol Cells 2016; 39:310-5. [PMID: 26912085 PMCID: PMC4844937 DOI: 10.14348/molcells.2016.2250] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/04/2015] [Accepted: 12/17/2015] [Indexed: 11/27/2022] Open
Abstract
Coumarin is a phenolic compound that mainly affects the liver due to its metabolization into a toxic compound. The deterrent and ovicidal activities of coumarin in insect models such as Drosophila melanogaster have been reported. Here we explore the molecular mechanisms by which these insects protect themselves and their eggs from this toxic plant metabolite. Coumarin was fatal to the flies in a dosage-dependent manner. However, coumarin feeding could be inhibited through activation of the aversive gustatory receptor neurons (GRNs), but not the olfactory receptor neurons. Furthermore, three gustatory receptors, GR33a, GR66a, and GR93a, functioned together in coumarin detection by the proboscis. However, GR33a, but not GR66a and GR93a, was required to avoid coumarin during oviposition, with a choice of the same substrates provided as in binary food choice assay. Taken together, these findings suggest that anti-feeding activity and oviposition to avoid coumarin occur via separate mechanisms.
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Affiliation(s)
- Seeta Poudel
- Department of Bio and Fermentation Convergence Technology, BK21 PLUS Project, Kookmin University, Seoul 136-702,
Korea
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, BK21 PLUS Project, Kookmin University, Seoul 136-702,
Korea
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