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Li Y, Ren Q, Bo T, Mo M, Liu Y. AWA and ASH Homologous Sensing Genes of Meloidogyne incognita Contribute to the Tomato Infection Process. Pathogens 2022; 11:pathogens11111322. [PMID: 36365073 PMCID: PMC9693415 DOI: 10.3390/pathogens11111322] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/07/2022] [Accepted: 11/07/2022] [Indexed: 11/12/2022] Open
Abstract
The AWA neurons of Caenorhabditis elegans mainly perceive volatile attractive odors, while the ASH neurons perceive pH, penetration, nociception, odor tropism, etc. The perceptual neurons of Meloidogyne incognita have been little studied. The number of infestations around and within tomato roots was significantly reduced after RNA interference for high-homology genes in AWA and ASH neurons compared between M. incognita and C. elegans. Through in situ hybridization, we further determined the expression and localization of the homologous genes Mi-odr-10 and Mi-gpa-6 in M. incognita. In this study, we found that M. incognita has neuronal sensing pathways similar to AWA and ASH perception of C. elegans for sensing chemical signals from tomato roots. Silencing the homologous genes in these pathways could affect the nematode perception and infestation of tomato root systems. The results contribute to elucidating the process of the plant host perception of M. incognita.
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Affiliation(s)
| | | | | | | | - Yajun Liu
- Correspondence: ; Tel.: +86-871-65031093
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2
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Microbiomes: How a gut bacterium promotes healthier living in a nematode. Curr Biol 2022; 32:R428-R430. [DOI: 10.1016/j.cub.2022.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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3
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Khanna A, Sellegounder D, Kumar J, Chamoli M, Vargas M, Chinta SJ, Rane A, Nelson C, Peiris TH, Brem R, Andersen J, Lithgow G, Kapahi P. Trimethylamine modulates dauer formation, neurodegeneration, and lifespan through tyra-3/daf-11 signaling in Caenorhabditis elegans. Aging Cell 2021; 20:e13351. [PMID: 33819374 PMCID: PMC8135002 DOI: 10.1111/acel.13351] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 02/10/2021] [Accepted: 03/05/2021] [Indexed: 11/27/2022] Open
Abstract
In the nematode Caenorhabditis elegans, signals derived from bacteria in the diet, the animal's major nutrient source, can modulate both behavior and healthspan. Here we describe a dual role for trimethylamine (TMA), a human gut flora metabolite, which acts as a nutrient signal and a neurotoxin. TMA and its associated metabolites are produced by the human gut microbiome and have been suggested to serve as risk biomarkers for diabetes and cardiovascular diseases. We demonstrate that the tyramine receptor TYRA-3, a conserved G protein-coupled receptor (GPCR), is required to sense TMA and mediate its responses. TMA activates guanylyl cyclase DAF-11 signaling through TYRA-3 in amphid neurons (ASK) and ciliated neurons (BAG) to mediate food-sensing behavior. Bacterial mutants deficient in TMA production enhance dauer formation, extend lifespan, and are less preferred as a food source. Increased levels of TMA lead to neural damage in models of Parkinson's disease and shorten lifespan. Our results reveal conserved signaling pathways modulated by TMA in C. elegans that are likely to be relevant for its effects in mammalian systems.
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Affiliation(s)
- Amit Khanna
- Buck Institute for Research on Aging Novato CA USA
- Dovetail Genomics LLC Scotts Valley CA USA
| | | | | | | | | | - Shankar J. Chinta
- Buck Institute for Research on Aging Novato CA USA
- Touro University California Vallejo CA USA
| | - Anand Rane
- Buck Institute for Research on Aging Novato CA USA
| | | | | | - Rachel Brem
- Buck Institute for Research on Aging Novato CA USA
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4
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Dauer Formation in C. elegans Is Modulated through AWC and ASI-Dependent Chemosensation. eNeuro 2021; 8:ENEURO.0473-20.2021. [PMID: 33712439 PMCID: PMC8174048 DOI: 10.1523/eneuro.0473-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/25/2021] [Accepted: 03/06/2021] [Indexed: 12/30/2022] Open
Abstract
The perception of our surrounding environment is an amalgamation of stimuli detected by sensory neurons. In Caenorhabditis elegans, olfaction is an essential behavior that determines various behavioral functions such as locomotion, feeding and development. Sensory olfactory cues also initiate downstream neuroendocrine signaling that controls aging, learning, development and reproduction. Innate sensory preferences toward odors (food, pathogens) and reproductive pheromones are modulated by 11 pairs of amphid chemosensory neurons in the head region of C. elegans. Amongst these sensory neurons, the ASI neuron has neuroendocrine functions and secretes neuropeptides, insulin-like peptide (DAF-28) and the TGF-β protein, DAF-7. Its expression levels are modulated by the presence of food (increased levels) and population density (decreased levels). A recent study has shown that EXP-1, an excitatory GABA receptor regulates DAF-7/TGF-β levels and participates in DAF-7/TGF-β-mediated behaviors such as aggregation and bordering. Here, we show that exp-1 mutants show defective responses toward AWC-sensed attractive odors in a non-autonomous manner through ASI neurons. Our dauer experiments reveal that in daf-7 mutants, ASI expressed EXP-1 and STR-2 (a G-protein-coupled receptor; GPCR) that partially maintained reproductive growth of animals. Further, studies suggest that neuronal connections between ASI and AWC neurons are allowed at least partially through ASI secreted DAF-7 or through alternate TGF- β pathway/s regulated by EXP-1 and STR-2. Together, our behavioral, genetic and imaging experiments propose that EXP-1 and STR-2 integrate food cues and allow the animals to display DAF-7/TGF-β neuroendocrine dependent or independent behavioral responses contributing to chemosensensory and developmental plasticity.
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5
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Ferkey DM, Sengupta P, L’Etoile ND. Chemosensory signal transduction in Caenorhabditis elegans. Genetics 2021; 217:iyab004. [PMID: 33693646 PMCID: PMC8045692 DOI: 10.1093/genetics/iyab004] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Chemosensory neurons translate perception of external chemical cues, including odorants, tastants, and pheromones, into information that drives attraction or avoidance motor programs. In the laboratory, robust behavioral assays, coupled with powerful genetic, molecular and optical tools, have made Caenorhabditis elegans an ideal experimental system in which to dissect the contributions of individual genes and neurons to ethologically relevant chemosensory behaviors. Here, we review current knowledge of the neurons, signal transduction molecules and regulatory mechanisms that underlie the response of C. elegans to chemicals, including pheromones. The majority of identified molecules and pathways share remarkable homology with sensory mechanisms in other organisms. With the development of new tools and technologies, we anticipate that continued study of chemosensory signal transduction and processing in C. elegans will yield additional new insights into the mechanisms by which this animal is able to detect and discriminate among thousands of chemical cues with a limited sensory neuron repertoire.
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Affiliation(s)
- Denise M Ferkey
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Noelle D L’Etoile
- Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143, USA
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6
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Hartman JH, Widmayer SJ, Bergemann CM, King DE, Morton KS, Romersi RF, Jameson LE, Leung MCK, Andersen EC, Taubert S, Meyer JN. Xenobiotic metabolism and transport in Caenorhabditis elegans. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2021; 24:51-94. [PMID: 33616007 PMCID: PMC7958427 DOI: 10.1080/10937404.2021.1884921] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Caenorhabditis elegans has emerged as a major model in biomedical and environmental toxicology. Numerous papers on toxicology and pharmacology in C. elegans have been published, and this species has now been adopted by investigators in academic toxicology, pharmacology, and drug discovery labs. C. elegans has also attracted the interest of governmental regulatory agencies charged with evaluating the safety of chemicals. However, a major, fundamental aspect of toxicological science remains underdeveloped in C. elegans: xenobiotic metabolism and transport processes that are critical to understanding toxicokinetics and toxicodynamics, and extrapolation to other species. The aim of this review was to initially briefly describe the history and trajectory of the use of C. elegans in toxicological and pharmacological studies. Subsequently, physical barriers to chemical uptake and the role of the worm microbiome in xenobiotic transformation were described. Then a review of what is and is not known regarding the classic Phase I, Phase II, and Phase III processes was performed. In addition, the following were discussed (1) regulation of xenobiotic metabolism; (2) review of published toxicokinetics for specific chemicals; and (3) genetic diversity of these processes in C. elegans. Finally, worm xenobiotic transport and metabolism was placed in an evolutionary context; key areas for future research highlighted; and implications for extrapolating C. elegans toxicity results to other species discussed.
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Affiliation(s)
- Jessica H Hartman
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Samuel J Widmayer
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States
| | | | - Dillon E King
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Katherine S Morton
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Riccardo F Romersi
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Laura E Jameson
- School of Mathematical and Natural Sciences, Arizona State University - West Campus, Glendale, Arizona, United States
| | - Maxwell C K Leung
- School of Mathematical and Natural Sciences, Arizona State University - West Campus, Glendale, Arizona, United States
| | - Erik C Andersen
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States
| | - Stefan Taubert
- Dept. Of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, the University of British Colombia, Vancouver, BC, Canada
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, North Carolina
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7
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The G-Protein-Coupled Receptor SRX-97 Is Required for Concentration-Dependent Sensing of Benzaldehyde in Caenorhabditis elegans. eNeuro 2021; 8:ENEURO.0011-20.2020. [PMID: 33397797 PMCID: PMC7877458 DOI: 10.1523/eneuro.0011-20.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 12/16/2022] Open
Abstract
The G-protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors (GPCRs) in the olfactory system function to sense the surrounding environment and respond to various odorants. The genes coding for olfactory receptors in Caenorhabditis elegans are larger in number in comparison to those in mammals, suggesting complexity in the receptor-odorant relationships. Recent studies have shown that the same odorant in different concentrations could act on multiple receptors in different neurons to induce attractive or repulsive responses. The ASH neurons are known to be responsible for responding to high concentrations of volatile odorants. Here, we characterize a new GPCR, SRX-97. We found that the srx-97 promoter drives expression specifically in the head ASH and tail PHB chemosensory neurons of C. elegans. Moreover, the SRX-97 protein localizes to the ciliary ends of the ASH neurons. Analysis of clustered regularly interspaced short palindromic repeats (CRISPR)-based deletion mutants of the srx-97 locus suggests that this gene is involved in recognition of high concentrations of benzaldehyde. This was further confirmed through rescue and neuronal ablation experiments. Our work brings novel insights into concentration-dependent receptor function in the olfactory system, and provides details of an additional molecule that helps the animal navigate its surroundings.
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8
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Sorathia N, Chawda N, Saraki K, Rajadhyaksha MS, Hejmadi M. hif-1 plays a role in hypoxia-induced gustatory plasticity of Caenorhabditis elegans. Int J Neurosci 2019; 129:864-870. [PMID: 30696318 DOI: 10.1080/00207454.2019.1576662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Background: Hypoxia-inducible factor 1 (HIF-1) is a key transcription factor in the detection of low oxygen levels, inducing expression of genes involved in mediating the response to hypoxia to maintain cellular oxygen homeostasis. Caenorhabditis elegans is a soil nematode that has evolved specialized chemosensory neurons that detect changes in oxygen levels and guide its behaviour and responses to food. The role of the hif-1 gene in modifying chemosensory behaviour in response to chemical hypoxia however remains unclear. Furthermore, the role of epigenetic modifiers in mediating this behavioural response to hypoxia is unclear. Aims: Our study addresses two questions (a) Do hypoxia-mimetics modify worm behaviour and (b) Are these behaviours modulated by HIF-dependent expression of epigenetic regulators? Material and methods: This study used established behavioural paradigms in hif-1 mutant strains of C. elegans, to study responses to chemical hypoxia. Results: We show that exposure to the hypoxia-mimetic, sodium sulphite, changes the gustatory responses, chemotaxis, gustatory plasticity and associative conditioning behaviour. Longer-term exposure to hypoxia changes the behavioural response of wild type C. elegans, mediated by the HIF pathway. Epigenetic modifiers, lithium chloride and valproic acid, further modulate these behavioural responses.
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Affiliation(s)
- Nabila Sorathia
- a Department of Life Sciences , Sophia College-Autonomous , Mumbai , India
| | - Neha Chawda
- a Department of Life Sciences , Sophia College-Autonomous , Mumbai , India
| | - Konstantina Saraki
- b Department of Biology & Biochemistry , University of Bath , Bath , United Kingdom
| | | | - Momna Hejmadi
- b Department of Biology & Biochemistry , University of Bath , Bath , United Kingdom
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9
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Paul ES, Mendl MT. Animal emotion: Descriptive and prescriptive definitions and their implications for a comparative perspective. Appl Anim Behav Sci 2018; 205:202-209. [PMID: 30078924 PMCID: PMC6041721 DOI: 10.1016/j.applanim.2018.01.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 11/16/2017] [Accepted: 01/21/2018] [Indexed: 01/24/2023]
Abstract
In recent years there has been a growing research interest in the field of animal emotion. But there is still little agreement about whether and how the word "emotion" should be defined for use in the context of non-human species. Here, we make a distinction between descriptive and prescriptive definitions. Descriptive definitions delineate the ways in which the word emotion is used in everyday life. Prescriptive definitions are used to pick out the set of events that scientific theories of emotion purport to explain. Picking out three prescriptive definitions, we show that the different ways in which emotions are defined correspond to processes that are distributed differentially across the animal kingdom. We propose that these definitions provide a useful starting point for investigating the varying emotional capacities of a wide range of animals, providing a basis for a new, comparative science of emotion.
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Affiliation(s)
- Elizabeth S. Paul
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol, BS40 5DU, UK
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10
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Kamireddy K, Chinnu S, Priyanka PS, Rajini PS, Giridhar P. Neuroprotective effect of Decalepis hamiltonii aqueous root extract and purified 2-hydroxy-4-methoxy benzaldehyde on 6-OHDA induced neurotoxicity in Caenorhabditis elegans. Biomed Pharmacother 2018; 105:997-1005. [PMID: 30021395 DOI: 10.1016/j.biopha.2018.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/01/2018] [Accepted: 06/02/2018] [Indexed: 01/01/2023] Open
Abstract
In this study, we investigated the possible neuroprotective efficacy of Decalepis hamiltonii tuber extract against 6-Hydroxy dopamine (6-OHDA) induced neurotoxicity and associated effects in Caenorhabditis elegans. The major component of flavour rich extract from D. hamiltonii is 2-hydroxy-4-methoxy benzaldehyde (2H4MB) which is an isomer of vanillin. We have conducted preliminary experiments with different types of extracts and subsequently DHFE (D. hamiltonii Fresh Tuber Extract) and DHPF (D. hamiltonii purified 2H4MB fraction) were used for further studies. Here we attempted to enumerate the neuroprotective efficacy of the above compounds in worms by evaluating behavioural and mitochondrial function, dopamine content and selective degeneration of dopaminergic neurons in BZ555 strains in comparison with control and 6-OHDA treated organisms. The relative expression levels of selected antioxidant genes involved in defence mechanism like SOD-3, GST-2 and GST-4 were evaluated along with those of CAT-2 and DOP-2 at mRNA level. We observed that both DHPF and DHFE exhibited significant levels of neuroprotective property against 6-OHDA induced neurotoxicity, which was evident in mitochondrial/dopaminergic function and antioxidant defence mechanism.
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Affiliation(s)
- Kiran Kamireddy
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India
| | - Salim Chinnu
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Food Protectants and Infestation Control Department, CSIR-CFTRI, Mysore, 570020, India
| | - P S Priyanka
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India
| | - P S Rajini
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Food Protectants and Infestation Control Department, CSIR-CFTRI, Mysore, 570020, India
| | - Parvatam Giridhar
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India.
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11
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Norflus F, Bu J, Guyton E, Gutekunst CA. Behavioral analysis of the huntingtin-associated protein 1 ortholog trak-1 in Caenorhabditis elegans. J Neurosci Res 2016; 94:850-6. [PMID: 27319755 DOI: 10.1002/jnr.23756] [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: 11/21/2015] [Revised: 04/04/2016] [Accepted: 04/04/2016] [Indexed: 11/06/2022]
Abstract
The precise role of huntingtin-associated protein 1 (HAP1) is not known, but studies have shown that it is important for early development and survival. A Caenorhabditis elegans ortholog of HAP1, T27A3.1 (also called trak-1), has been found and is expressed in a subset of neurons. Potential behavioral functions of three knockout lines of T27A3.1 were examined. From its suspected role in mice we hypothesize that T27A3.1 might be involved in egg hatching and early growth, mechanosensation, chemosensation, sensitivity to osmolarity, and synaptic transmission. Our studies show that the knockout worms are significantly different from the wild-type (WT) worms only in the synaptic transmission test, which was measured by adding aldicarb, an acetylcholinesterase inhibitor. The change in function was determined by measuring the number of worms paralyzed. However, when the T27A3.1 worms were tested for egg hatching and early growth, mechanosensation, chemosensation, and sensitivity to osmolarity, there were no significant differences between the knockout and WT worms. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Fran Norflus
- Department of Biology, Clayton State University, Morrow, Georgia
| | - Jingnan Bu
- Department of Neurosurgery, Emory University, Atlanta, Georgia
| | - Evon Guyton
- Department of Biology, Clayton State University, Morrow, Georgia
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12
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Taniguchi G, Uozumi T, Kiriyama K, Kamizaki T, Hirotsu T. Screening of odor-receptor pairs in Caenorhabditis elegans reveals different receptors for high and low odor concentrations. Sci Signal 2014; 7:ra39. [PMID: 24782565 DOI: 10.1126/scisignal.2005136] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Olfactory systems sense and respond to various odorants. Olfactory receptors, which in most organisms are G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors, directly bind volatile or soluble odorants. Compared to the genomes of mammals, the genome of the nematode Caenorhabditis elegans contains more putative olfactory receptor genes, suggesting that in nematodes there may be combinatorial complexity to the receptor-odor relationship. We used RNA interference (RNAi) screening to identify nematode olfactory receptors necessary for the response to specific odorants. This screening identified 194 candidate olfactory receptor genes linked to 11 odorants. Additionally, we identified SRI-14 as being involved in sensing high concentrations of diacetyl. Rescue and neuron-specific RNAi experiments demonstrated that SRI-14 functioned in ASH neurons, specific chemosensory neurons, resulting in avoidance responses. Calcium imaging revealed that ASH neurons responded to high diacetyl concentrations only, whereas another class of chemosensory neurons, AWA neurons, reacted to both low and high concentrations. Loss of SRI-14 function hampered ASH responses to high diacetyl concentrations, whereas loss of ODR-10 function reduced AWA responses to low odorant concentrations. Chemosensory neurons ectopically expressing SRI-14 responded to a high concentration of diacetyl. Thus, nematodes have concentration-dependent odor-sensing mechanisms that are segregated at the olfactory receptor and sensory neuron levels.
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Affiliation(s)
- Gun Taniguchi
- 1Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 812-8581, Japan
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13
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Anderson DJ, Adolphs R. A framework for studying emotions across species. Cell 2014; 157:187-200. [PMID: 24679535 PMCID: PMC4098837 DOI: 10.1016/j.cell.2014.03.003] [Citation(s) in RCA: 328] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 02/18/2014] [Accepted: 03/02/2014] [Indexed: 10/25/2022]
Abstract
Since the 19th century, there has been disagreement over the fundamental question of whether "emotions" are cause or consequence of their associated behaviors. This question of causation is most directly addressable in genetically tractable model organisms, including invertebrates such as Drosophila. Yet there is ongoing debate about whether such species even have "emotions," as emotions are typically defined with reference to human behavior and neuroanatomy. Here, we argue that emotional behaviors are a class of behaviors that express internal emotion states. These emotion states exhibit certain general functional and adaptive properties that apply across any specific human emotions like fear or anger, as well as across phylogeny. These general properties, which can be thought of as "emotion primitives," can be modeled and studied in evolutionarily distant model organisms, allowing functional dissection of their mechanistic bases and tests of their causal relationships to behavior. More generally, our approach not only aims at better integration of such studies in model organisms with studies of emotion in humans, but also suggests a revision of how emotion should be operationalized within psychology and psychiatry.
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Affiliation(s)
- David J Anderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Ralph Adolphs
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Division of Humanities and Social Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
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14
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Smith HK, Luo L, O’Halloran D, Guo D, Huang XY, Samuel ADT, Hobert O. Defining specificity determinants of cGMP mediated gustatory sensory transduction in Caenorhabditis elegans. Genetics 2013; 194:885-901. [PMID: 23695300 PMCID: PMC3730918 DOI: 10.1534/genetics.113.152660] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 05/18/2013] [Indexed: 12/21/2022] Open
Abstract
Cyclic guanosine monophosphate (cGMP) is a key secondary messenger used in signal transduction in various types of sensory neurons. The importance of cGMP in the ASE gustatory receptor neurons of the nematode Caenorhabditis elegans was deduced by the observation that multiple receptor-type guanylyl cyclases (rGCs), encoded by the gcy genes, and two presently known cyclic nucleotide-gated ion channel subunits, encoded by the tax-2 and tax-4 genes, are essential for ASE-mediated gustatory behavior. We describe here specific mechanistic features of cGMP-mediated signal transduction in the ASE neurons. First, we assess the specificity of the sensory functions of individual rGC proteins. We have previously shown that multiple rGC proteins are expressed in a left/right asymmetric manner in the functionally lateralized ASE neurons and are required to sense distinct salt cues. Through domain swap experiments among three different rGC proteins, we show here that the specificity of individual rGC proteins lies in their extracellular domains and not in their intracellular, signal-transducing domains. Furthermore, we find that rGC proteins are also sufficient to confer salt sensory responses to other neurons. Both findings support the hypothesis that rGC proteins are salt receptor proteins. Second, we identify a novel, likely downstream effector of the rGC proteins in gustatory signal transduction, a previously uncharacterized cyclic nucleotide-gated (CNG) ion channel, encoded by the che-6 locus. che-6 mutants show defects in gustatory sensory transduction that are similar to defects observed in animals lacking the tax-2 and tax-4 CNG channels. In contrast, thermosensory signal transduction, which also requires tax-2 and tax-4, does not require che-6, but requires another CNG, cng-3. We propose that CHE-6 may form together with two other CNG subunits, TAX-2 and TAX-4, a gustatory neuron-specific heteromeric CNG channel complex.
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Affiliation(s)
- Heidi K. Smith
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York 10032
| | - Linjiao Luo
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138
| | - Damien O’Halloran
- Department of Biological Sciences and Institute for Neuroscience, George Washington University, Washington DC, 20037
| | - Dagang Guo
- Department of Physiology, Cornell University Weill Medical College, New York, New York 10065
| | - Xin-Yun Huang
- Department of Physiology, Cornell University Weill Medical College, New York, New York 10065
| | - Aravinthan D. T. Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138
| | - Oliver Hobert
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York 10032
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138
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15
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Abstract
Many species use bilateral sampling for odor-guided navigation. Bilateral localization strategies typically involve balanced and lateralized sensory input and early neuronal processing. For example, if gradient direction is estimated by differential sampling, then any asymmetry could bias the perceived direction. Subsequent neuronal processing can compensate for this asymmetry but requires the presence of mechanisms to track changes in asymmetry. A high degree of laterality is also important for differential sampling because spillover of signals will dilute the perceived odor gradient. In apparent contradiction to this model, both symmetry and laterality of nasal air flow have been reported to be incomplete in rats. Here, we measured symmetry and laterality in early olfactory processing in the rat. We first established behavioral readouts of precisely controlled bilateral odorant stimuli. We found that rats could rapidly and accurately report the direction of a wide range of odor gradients, presented in random sequence. We then showed that nasal air flow was symmetric over an entire day in awake rats. Furthermore, odor sampling from the two nostrils in the behavioral task was highly lateralized. This lateralization extended to the receptor epithelium responses as measured by electro-olfactograms. We finally observed strong lateralization of intrinsic signal responses from the glomerular layer of the olfactory bulb. We confirmed that a differential comparison of glomerular responses was sufficient to localize odorants. Together, these results suggest that the rat olfactory system is symmetric, with highly lateralized odor flow and neuronal responses. In combination, these attributes support odor localization by differential comparison.
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Lau HL, Timbers TA, Mahmoud R, Rankin CH. Genetic dissection of memory for associative and non-associative learning inCaenorhabditis elegans. GENES BRAIN AND BEHAVIOR 2012; 12:210-23. [DOI: 10.1111/j.1601-183x.2012.00863.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 08/30/2012] [Accepted: 09/22/2012] [Indexed: 01/20/2023]
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Musselman HN, Neal-Beliveau B, Nass R, Engleman EA. Chemosensory cue conditioning with stimulants in a Caenorhabditis elegans animal model of addiction. Behav Neurosci 2012; 126:445-56. [PMID: 22642886 PMCID: PMC3367381 DOI: 10.1037/a0028303] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The underlying molecular mechanisms of drug abuse and addiction behaviors are poorly understood. Caenorhabditis elegans (C. elegans) provide a simple, whole animal model with conserved molecular pathways well suited for studying the foundations of complex diseases. Historically, chemotaxis has been a measure used to examine sensory approach and avoidance behavior in worms. Chemotaxis can be modulated by previous experience, and cue-dependent conditioned learning has been demonstrated in C. elegans, but such conditioning with drugs of abuse has not been reported. Here we show that pairing a distinctive salt cue with a drug (cocaine or methamphetamine) results in a concentration-dependent change in preference for the cue that was paired with the drug during conditioning. Further, we demonstrate that pairing of either drug with a distinctive food type can also increase preference for the drug-paired food in the absence of the drug. Dopamine-deficient mutants did not develop drug-paired, cue-conditioned responses. The findings suggest that, like vertebrates, C. elegans display a conditioned preference for environments containing cues previously associated with drugs of abuse, and this response is dependent on dopamine neurotransmission. This model provides a new and powerful method to study the genetic and molecular mechanisms that mediate drug preference.
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Liao C, Gock A, Michie M, Morton B, Anderson A, Trowell S. Behavioural and genetic evidence for C. elegans' ability to detect volatile chemicals associated with explosives. PLoS One 2010; 5:e12615. [PMID: 20830309 PMCID: PMC2935383 DOI: 10.1371/journal.pone.0012615] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 08/13/2010] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Automated standoff detection and classification of explosives based on their characteristic vapours would be highly desirable. Biologically derived odorant receptors have potential as the explosive recognition element in novel biosensors. Caenorhabditis elegans' genome contains over 1,000 uncharacterised candidate chemosensory receptors. It was not known whether any of these respond to volatile chemicals derived from or associated with explosives. METHODOLOGY/PRINCIPAL FINDINGS We assayed C. elegans for chemotactic responses to chemical vapours of explosives and compounds associated with explosives. C. elegans failed to respond to many of the explosive materials themselves but showed strong chemotaxis with a number of compounds associated with commercial or homemade explosives. Genetic mutant strains were used to identify the likely neuronal location of a putative receptor responding to cyclohexanone, which is a contaminant of some compounded explosives, and to identify the specific transduction pathway involved. Upper limits on the sensitivity of the nematode were calculated. A sensory adaptation protocol was used to estimate the receptive range of the receptor. CONCLUSIONS/SIGNIFICANCE The results suggest that C. elegans may be a convenient source of highly sensitive, narrowly tuned receptors to detect a range of explosive-associated volatiles.
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Affiliation(s)
- Chunyan Liao
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Andrew Gock
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Michelle Michie
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Bethany Morton
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Alisha Anderson
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Stephen Trowell
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
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Fu Y, Ren M, Feng H, Chen L, Altun ZF, Rubin CS. Neuronal and intestinal protein kinase d isoforms mediate Na+ (salt taste)-induced learning. Sci Signal 2009; 2:ra42. [PMID: 19671928 DOI: 10.1126/scisignal.2000224] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ubiquitously expressed protein kinase D (PKD) isoforms are poised to disseminate signals carried by diacylglycerol (DAG). However, the in vivo regulation and functions of PKDs are poorly understood. We show that the Caenorhabditis elegans gene, dkf-2, encodes not just DKF-2A, but also a second previously unknown isoform, DKF-2B. Whereas DKF-2A is present mainly in intestine, we show that DKF-2B is found in neurons. Characterization of dkf-2 null mutants and transgenic animals expressing DKF-2B, DKF-2A, or both isoforms revealed that PKDs couple DAG signals to regulation of sodium ion (Na+)-induced learning. EGL-8 (a phospholipase Cbeta4 homolog) and TPA-1 (a protein kinase Cdelta homolog) are upstream regulators of DKF-2 isoforms in vivo. Thus, pathways containing EGL-8-TPA-1-DKF-2 enable learning and behavioral plasticity by receiving, transmitting, and cooperatively integrating environmental signals targeted to both neurons and intestine.
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Affiliation(s)
- Ya Fu
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Berna AZ, Anderson AR, Trowell SC. Bio-benchmarking of electronic nose sensors. PLoS One 2009; 4:e6406. [PMID: 19641604 PMCID: PMC2712691 DOI: 10.1371/journal.pone.0006406] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Accepted: 06/19/2009] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Electronic noses, E-Noses, are instruments designed to reproduce the performance of animal noses or antennae but generally they cannot match the discriminating power of the biological original and have, therefore, been of limited utility. The manner in which odorant space is sampled is a critical factor in the performance of all noses but so far it has been described in detail only for the fly antenna. METHODOLOGY Here we describe how a set of metal oxide (MOx) E-Nose sensors, which is the most commonly used type, samples odorant space and compare it with what is known about fly odorant receptors (ORs). PRINCIPAL FINDINGS Compared with a fly's odorant receptors, MOx sensors from an electronic nose are on average more narrowly tuned but much more highly correlated with each other. A set of insect ORs can therefore sample broader regions of odorant space independently and redundantly than an equivalent number of MOx sensors. The comparison also highlights some important questions about the molecular nature of fly ORs. CONCLUSIONS The comparative approach generates practical learnings that may be taken up by solid-state physicists or engineers in designing new solid-state electronic nose sensors. It also potentially deepens our understanding of the performance of the biological system.
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Affiliation(s)
- Amalia Z. Berna
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Alisha R. Anderson
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
| | - Stephen C. Trowell
- CSIRO Entomology and CSIRO Food Futures Flagship, Canberra, Australian Capital Territory, Australia
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Smart R, Kiely A, Beale M, Vargas E, Carraher C, Kralicek AV, Christie DL, Chen C, Newcomb RD, Warr CG. Drosophila odorant receptors are novel seven transmembrane domain proteins that can signal independently of heterotrimeric G proteins. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2008; 38:770-780. [PMID: 18625400 DOI: 10.1016/j.ibmb.2008.05.002] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 05/12/2008] [Accepted: 05/12/2008] [Indexed: 05/26/2023]
Abstract
Olfaction in Drosophila is mediated by a large family of membrane-bound odorant receptor proteins (Ors). In heterologous cells, we investigated whether the structural features and signalling mechanisms of ligand-binding Drosophila Ors are consistent with them being G protein-coupled receptors (GPCRs). The detailed membrane topology of Or22a was determined by inserting epitope tags into the termini and predicted loop regions. Immunocytochemistry experiments in Drosophila S2 cells imply that Or22a has seven transmembrane domains but that its membrane topology is opposite to that of GPCRs, with a cytoplasmic N-terminus and extracellular C-terminus. To investigate Or signalling mechanisms, we expressed Or43b in Sf9 and HEK293 cells, and show that inhibitors of heterotrimeric G proteins (GDP-beta-S), adenylate cyclase (SQ22536), guanylyl cyclase (ODQ), cyclic nucleotide phosphodiesterases (IBMX) and phospholipase C (U73122) have negligible impact on Or43b responses. Whole cell patching of Or43b/Or83b-transfected HEK293 cells revealed the opening of plasma membrane cation channels on addition of ligand. The response was blocked by lanthanum and by 2-APB, but not by Ruthenium red or SKF96365. Based on these data, we conclude that Drosophila Ors comprise a novel family of seven transmembrane receptors that in HEK293 cells signal by opening cation channels, through a mechanism that is largely independent of G proteins.
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Affiliation(s)
- Renee Smart
- School of Biological Sciences, Monash University, Melbourne, Vic. 3800, Australia
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Luo L, Gabel CV, Ha HI, Zhang Y, Samuel ADT. Olfactory Behavior of Swimming C. elegans Analyzed by Measuring Motile Responses to Temporal Variations of Odorants. J Neurophysiol 2008; 99:2617-25. [DOI: 10.1152/jn.00053.2008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Caenorhabditis elegans responds to chemical cues using a small number of chemosensory neurons that detect a large variety of molecules in its environment. During chemotaxis, C. elegans biases its migration in spatial chemical gradients by lengthening (/shortening) periods of forward movement when it happens to be moving toward (/away) from preferred locations. In classical assays of chemotactic behavior, a group of crawling worms is placed on an agar plate containing a point source of chemical, the group is allowed to navigate for a period of time, and aggregation of worms near the source is quantified. Here we show that swimming worms exhibit acute motile responses to temporal variations of odor in their surrounding environment, allowing our development of an automated assay of chemotactic behavior with single-animal resolution. By placing individual worms in small microdroplets and quantifying their movements as they respond to the addition and removal of odorized airstreams, we show that the sensorimotor phenotypes of swimming worms (wild-type behavior, the effects of certain mutations, and the effects of laser ablation of specific olfactory neurons) are consistent with aggregation phenotypes previously obtained in crawling assays. The microdroplet swimming assay has certain advantages over crawling assays, including flexibility and precision in defining the stimulus waveform and automated quantification of motor response during stimulus presentation. In this study, we use the microdroplet assay to quantify the temporal dynamics of the olfactory response, the sensitivity to odorant concentration, combinations, and gradients, and the contribution of specific olfactory neurons to overall behavior.
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Lee K, Portman DS. Neural Sex Modifies the Function of a C. elegans Sensory Circuit. Curr Biol 2007; 17:1858-63. [DOI: 10.1016/j.cub.2007.10.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 09/28/2007] [Accepted: 10/01/2007] [Indexed: 11/16/2022]
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