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Schoofs A, Miroschnikow A, Schlegel P, Zinke I, Schneider-Mizell CM, Cardona A, Pankratz MJ. Serotonergic modulation of swallowing in a complete fly vagus nerve connectome. Curr Biol 2024:S0960-9822(24)01137-0. [PMID: 39270641 DOI: 10.1016/j.cub.2024.08.025] [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: 02/06/2024] [Revised: 07/15/2024] [Accepted: 08/15/2024] [Indexed: 09/15/2024]
Abstract
How the body interacts with the brain to perform vital life functions, such as feeding, is a fundamental issue in physiology and neuroscience. Here, we use a whole-animal scanning transmission electron microscopy volume of Drosophila to map the neuronal circuits that connect the entire enteric nervous system to the brain via the insect vagus nerve at synaptic resolution. We identify a gut-brain feedback loop in which Piezo-expressing mechanosensory neurons in the esophagus convey food passage information to a cluster of six serotonergic neurons in the brain. Together with information on food value, these central serotonergic neurons enhance the activity of serotonin receptor 7-expressing motor neurons that drive swallowing. This elemental circuit architecture includes an axo-axonic synaptic connection from the glutamatergic motor neurons innervating the esophageal muscles onto the mechanosensory neurons that signal to the serotonergic neurons. Our analysis elucidates a neuromodulatory sensory-motor system in which ongoing motor activity is strengthened through serotonin upon completion of a biologically meaningful action, and it may represent an ancient form of motor learning.
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Affiliation(s)
- Andreas Schoofs
- Department of Molecular Brain Physiology and Behavior, LIMES Institute, University of Bonn, Carl-Troll-Straße, Bonn 53115, Germany
| | - Anton Miroschnikow
- Department of Molecular Brain Physiology and Behavior, LIMES Institute, University of Bonn, Carl-Troll-Straße, Bonn 53115, Germany
| | - Philipp Schlegel
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 TN1, UK; MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Trumpington, Cambridge CB2 0QH, UK
| | - Ingo Zinke
- Department of Molecular Brain Physiology and Behavior, LIMES Institute, University of Bonn, Carl-Troll-Straße, Bonn 53115, Germany
| | | | - Albert Cardona
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Trumpington, Cambridge CB2 0QH, UK; Janelia Research Campus, Howard Hughes Medical Institute, Helix Drive, Ashburn, VA 20147, USA; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Place, Cambridge CB2 3EL, UK
| | - Michael J Pankratz
- Department of Molecular Brain Physiology and Behavior, LIMES Institute, University of Bonn, Carl-Troll-Straße, Bonn 53115, Germany.
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2
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Rodrigues DT, Padilha HA, Soares ATG, de Souza MEO, Guerra MT, Ávila DS. The Caenorhabditis elegans neuroendocrine system and their modulators: An overview. Mol Cell Endocrinol 2024; 586:112191. [PMID: 38382589 DOI: 10.1016/j.mce.2024.112191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 02/23/2024]
Abstract
In this review we seek to systematically bring what has been published in the literature about the nervous system, endocrine system, neuroendocrine relationships, neuroendocrine modulations and endocrine disruptors in the alternative model Caenorhabditis elegans. The serotonergic, dopaminergic, GABAergic and glutamatergic neurotransmitters are related to the modulation of the neuroendocrine axis, leading to the activation or inhibition of several processes that occur in the worm through distinct and interconnected pathways. Furthermore, this review addresses the gut-neuronal axis as it has been revealed in recent years that gut microbiota impacts on neuronal functions. This review also approaches xenobiotics that can positively or negatively impact the neuroendocrine system in C. elegans as in mammals, which allows the application of this nematode to screen new drugs and to identify toxicants that are endocrine disruptors.
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Affiliation(s)
- Daniela Teixeira Rodrigues
- Graduation Program in Biological Sciences- Toxicological Biochemistry, Federal University of Santa Maria, RS, Brazil
| | | | | | | | | | - Daiana Silva Ávila
- Graduation Program in Biological Sciences- Toxicological Biochemistry, Federal University of Santa Maria, RS, Brazil; Graduation Program in Biochemistry, Federal University of Pampa, Uruguaiana, RS, Brazil.
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3
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Gowripriya T, Yashwanth R, James Prabhanand B, Suresh R, Balamurugan K. Klebsiella aerogenes ingestion elicits behavioral changes and innate immunity in the host, Caenorhabditis elegans. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 154:105138. [PMID: 38286197 DOI: 10.1016/j.dci.2024.105138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/18/2024] [Accepted: 01/20/2024] [Indexed: 01/31/2024]
Abstract
Klebsiella aerogenes (previously known as Enterobacter aerogenes) is a common opportunistic pathogen that infect the respiratory tract and central nervous system. However, how it interferes the host regulatory mechanism has not been previously described. When C. elegans were exposed to K. aerogenes, they exhibited a shorter lifespan compared to those fed with E. coli OP50. The time required for 50 % of L4 hermaphrodite nematodes to die when exposed to K. aerogenes was approximately 9 days, whereas it was about 18 days when fed with E. coli OP50. The interaction with K. aerogenes also affected the physical activity of C. elegans. Parameters like pharyngeal pumping, head thrashing, body bending, and swimming showed a gradual decline during infection. The expression of serotonin-mediated axon regeneration K. aerogenes infection led to increased levels of reactive oxygen species (ROS) in C. elegans compared to E. coli OP50-fed worms. The nematodes activated antioxidant mechanisms, including the expression of SODs, to counteract elevated ROS levels. The interaction with K. aerogenes activated immune regulatory pathways in C. elegans, including the mTOR signaling pathway downstream player SGK-1. Lifespan regulatory pathways, such as pha-4 and pmk-1, were also affected, likely contributing to the nematode ability to survive in a pathogenic environment. K. aerogenes infection has a detrimental impact on the healthspan and lifespan of C. elegans, affecting physical activity, intestinal health, serotonin regulation, ROS levels, and immune responses. These findings provide insights into the complex interactions between K. aerogenes and host organisms.
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Affiliation(s)
- Thirumugam Gowripriya
- Department of Biotechnology, Science Campus, Alagappa University, Karaikudi, 630 003, India.
| | - Radhakrishnan Yashwanth
- ITC Life Sciences and Technology Centre, Peenya Industrial Area, Bangalore, 560 058, Karnataka, India.
| | - Bhaskar James Prabhanand
- ITC Life Sciences and Technology Centre, Peenya Industrial Area, Bangalore, 560 058, Karnataka, India.
| | - Ramamurthi Suresh
- ITC Life Sciences and Technology Centre, Peenya Industrial Area, Bangalore, 560 058, Karnataka, India.
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4
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Ding SS, Fox JL, Gordus A, Joshi A, Liao JC, Scholz M. Fantastic beasts and how to study them: rethinking experimental animal behavior. J Exp Biol 2024; 227:jeb247003. [PMID: 38372042 PMCID: PMC10911175 DOI: 10.1242/jeb.247003] [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: 02/20/2024]
Abstract
Humans have been trying to understand animal behavior at least since recorded history. Recent rapid development of new technologies has allowed us to make significant progress in understanding the physiological and molecular mechanisms underlying behavior, a key goal of neuroethology. However, there is a tradeoff when studying animal behavior and its underlying biological mechanisms: common behavior protocols in the laboratory are designed to be replicable and controlled, but they often fail to encompass the variability and breadth of natural behavior. This Commentary proposes a framework of 10 key questions that aim to guide researchers in incorporating a rich natural context into their experimental design or in choosing a new animal study system. The 10 questions cover overarching experimental considerations that can provide a template for interspecies comparisons, enable us to develop studies in new model organisms and unlock new experiments in our quest to understand behavior.
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Affiliation(s)
- Siyu Serena Ding
- Max Planck Institute of Animal Behavior, 78464 Konstanz, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78464 Konstanz, Germany
| | - Jessica L. Fox
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Andrew Gordus
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Abhilasha Joshi
- Departments of Physiology and Psychiatry, University of California, San Francisco, CA 94158, USA
| | - James C. Liao
- Department of Biology, The Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080, USA
| | - Monika Scholz
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesar, 53175 Bonn, Germany
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5
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The Assembly of Bacteria Living in Natural Environments Shapes Neuronal Integrity and Behavioral Outputs in Caenorhabditis elegans. mBio 2023; 14:e0340222. [PMID: 36883821 PMCID: PMC10127743 DOI: 10.1128/mbio.03402-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Bacterivore nematodes are the most abundant animals in the biosphere, largely contributing to global biogeochemistry. Thus, the effects of environmental microbes on the nematodes' life-history traits are likely to contribute to the general health of the biosphere. Caenorhabditis elegans is an excellent model to study the behavioral and physiological outputs of microbial diets. However, the effects of complex natural bacterial assemblies have only recently been reported, as most studies have been carried out with monoxenic cultures of laboratory-reared bacteria. Here, we quantified the physiological, phenotypic, and behavioral traits of C. elegans feeding on two bacteria that were coisolated with wild nematodes from a soil sample. These bacteria were identified as a putative novel species of Stenotrophomonas named Stenotrophomonas sp. strain Iso1 and a strain of Bacillus pumilus designated Iso2. The distinctive behaviors and developmental patterns observed in animals fed with individual isolates changed when bacteria were mixed. We studied in more depth the degeneration rate of the touch circuit of C. elegans and show that B. pumilus alone is protective, while the mix with Stenotrophomonas sp. is degenerative. The analysis of the metabolite contents of each isolate and their combination identified NAD+ as being potentially neuroprotective. In vivo supplementation shows that NAD+ restores neuroprotection to the mixes and also to individual nonprotective bacteria. Our results highlight the distinctive physiological effects of bacteria resembling native diets in a multicomponent scenario rather than using single isolates on nematodes. IMPORTANCE Do behavioral choices depend on animals' microbiota? To answer this question, we studied how different bacterial assemblies impact the life-history traits of the bacterivore nematode C. elegans using isolated bacteria found in association with wild nematodes in Chilean soil. We identified the first isolate, Iso1, as a novel species of Stenotrophomonas and isolate Iso2 as Bacillus pumilus. We find that worm traits such as food choice, pharyngeal pumping, and neuroprotection, among others, are dependent on the biota composition. For example, the neurodegeneration of the touch circuit needed to sense and escape from predators in the wild decreases when nematodes are fed on B. pumilus, while its coculture with Stenotrophomonas sp. eliminates neuroprotection. Using metabolomics analysis, we identify metabolites such as NAD+, present in B. pumilus yet lost in the mix, as being neuroprotective and validated their protective effects using in vivo experiments.
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6
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Bonnard E, Liu J, Zjacic N, Alvarez L, Scholz M. Automatically tracking feeding behavior in populations of foraging C. elegans. eLife 2022; 11:e77252. [PMID: 36083280 PMCID: PMC9462848 DOI: 10.7554/elife.77252] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Caenorhabditis elegans feeds on bacteria and other small microorganisms which it ingests using its pharynx, a neuromuscular pump. Currently, measuring feeding behavior requires tracking a single animal, indirectly estimating food intake from population-level metrics, or using restrained animals. To enable large throughput feeding measurements of unrestrained, crawling worms on agarose plates at a single worm resolution, we developed an imaging protocol and a complementary image analysis tool called PharaGlow. We image up to 50 unrestrained crawling worms simultaneously and extract locomotion and feeding behaviors. We demonstrate the tool's robustness and high-throughput capabilities by measuring feeding in different use-case scenarios, such as through development, with genetic and chemical perturbations that result in faster and slower pumping, and in the presence or absence of food. Finally, we demonstrate that our tool is capable of long-term imaging by showing behavioral dynamics of mating animals and worms with different genetic backgrounds. The low-resolution fluorescence microscopes required are readily available in C. elegans laboratories, and in combination with our python-based analysis workflow makes this methodology easily accessible. PharaGlow therefore enables the observation and analysis of the temporal dynamics of feeding and locomotory behaviors with high-throughput and precision in a user-friendly system.
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Affiliation(s)
- Elsa Bonnard
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Jun Liu
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Nicolina Zjacic
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
- Institute of Medical Genetics, University of ZurichZurichSwitzerland
| | - Luis Alvarez
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Monika Scholz
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
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7
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The evolving role of the Caenorhabditis elegans model as a tool to advance studies in nutrition and health. Nutr Res 2022; 106:47-59. [DOI: 10.1016/j.nutres.2022.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 12/29/2022]
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8
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Zjacic N, Scholz M. The role of food odor in invertebrate foraging. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12793. [PMID: 34978135 PMCID: PMC9744530 DOI: 10.1111/gbb.12793] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/01/2021] [Accepted: 12/18/2021] [Indexed: 11/30/2022]
Abstract
Foraging for food is an integral part of animal survival. In small insects and invertebrates, multisensory information and optimized locomotion strategies are used to effectively forage in patchy and complex environments. Here, the importance of olfactory cues for effective invertebrate foraging is discussed in detail. We review how odors are used by foragers to move toward a likely food source and the recent models that describe this sensory-driven behavior. We argue that smell serves a second function by priming an organism for the efficient exploitation of food. By appraising food odors, invertebrates can establish preferences and better adapt to their ecological niches, thereby promoting survival. The smell of food pre-prepares the gastrointestinal system and primes feeding motor programs for more effective ingestion as well. Optimizing resource utilization affects longevity and reproduction as a result, leading to drastic changes in survival. We propose that models of foraging behavior should include odor priming, and illustrate this with a simple toy model based on the marginal value theorem. Lastly, we discuss the novel techniques and assays in invertebrate research that could investigate the interactions between odor sensing and food intake. Overall, the sense of smell is indispensable for efficient foraging and influences not only locomotion, but also organismal physiology, which should be reflected in behavioral modeling.
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Affiliation(s)
- Nicolina Zjacic
- Max Planck Research Group Neural Information FlowCenter of Advanced European Studies and Research (Caesar)BonnGermany
| | - Monika Scholz
- Max Planck Research Group Neural Information FlowCenter of Advanced European Studies and Research (Caesar)BonnGermany
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9
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Schiffer JA, Stumbur SV, Seyedolmohadesin M, Xu Y, Serkin WT, McGowan NG, Banjo O, Torkashvand M, Lin A, Hosea CN, Assié A, Samuel BS, O’Donnell MP, Venkatachalam V, Apfeld J. Modulation of sensory perception by hydrogen peroxide enables Caenorhabditis elegans to find a niche that provides both food and protection from hydrogen peroxide. PLoS Pathog 2021; 17:e1010112. [PMID: 34941962 PMCID: PMC8699984 DOI: 10.1371/journal.ppat.1010112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/14/2021] [Indexed: 02/07/2023] Open
Abstract
Hydrogen peroxide (H2O2) is the most common chemical threat that organisms face. Here, we show that H2O2 alters the bacterial food preference of Caenorhabditis elegans, enabling the nematodes to find a safe environment with food. H2O2 induces the nematodes to leave food patches of laboratory and microbiome bacteria when those bacterial communities have insufficient H2O2-degrading capacity. The nematode's behavior is directed by H2O2-sensing neurons that promote escape from H2O2 and by bacteria-sensing neurons that promote attraction to bacteria. However, the input for H2O2-sensing neurons is removed by bacterial H2O2-degrading enzymes and the bacteria-sensing neurons' perception of bacteria is prevented by H2O2. The resulting cross-attenuation provides a general mechanism that ensures the nematode's behavior is faithful to the lethal threat of hydrogen peroxide, increasing the nematode's chances of finding a niche that provides both food and protection from hydrogen peroxide.
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Affiliation(s)
- Jodie A. Schiffer
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Stephanie V. Stumbur
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Maedeh Seyedolmohadesin
- Physics Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Yuyan Xu
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
| | - William T. Serkin
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Natalie G. McGowan
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Oluwatosin Banjo
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Mahdi Torkashvand
- Physics Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Albert Lin
- Department of Physics, Center for Brain Science, Harvard University, Cambridge, Massachusetts, United States of America
| | - Ciara N. Hosea
- Alkek Center for Metagenomics and Microbiome Research and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Adrien Assié
- Alkek Center for Metagenomics and Microbiome Research and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Buck S. Samuel
- Alkek Center for Metagenomics and Microbiome Research and Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Michael P. O’Donnell
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Vivek Venkatachalam
- Physics Department, Northeastern University, Boston, Massachusetts, United States of America
| | - Javier Apfeld
- Biology Department, Northeastern University, Boston, Massachusetts, United States of America
- Bioengineering Department, Northeastern University, Boston, Massachusetts, United States of America
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10
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Gaur AV, Agarwal R. Risperidone induced alterations in feeding and locomotion behavior of Caenorhabditis elegans. Curr Res Toxicol 2021; 2:367-374. [PMID: 34806037 PMCID: PMC8585583 DOI: 10.1016/j.crtox.2021.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 11/19/2022] Open
Abstract
Antipsychotic drugs (APDs) are prescribed for the treatment of psychiatric illness. However, these drugs can also contribute to several developmental and behavioral disorders. Contemporary studies to evaluate the toxic effects of numerous atypical antipsychotics are reported to cause behavioral alteration at variable doses in mammals and nematodes. Risperidone, the second most prescribed drug in India, requires more exploration of its adverse effects on humans. Here, we explore effects on feeding behavior and locomotion patterns due to risperidone exposure in C. elegans model. The study targets to work out the toxic effects of risperidone exposure on feeding and locomotion behavior in addition to the expected pharmacological effects. N2 wild type strain was exposed in liquid culture assay for 2, 4, 6, 8, 10, and 12 hours with fixed 50 µM concentration. Feeding behavior was depleted due to inhibition in pharyngeal pumping varying from 11.05% - 45.67% in a time-dependent manner. Results of locomotion assay also show time-varying increase in reversals (4.9%-34.03%) and omega bends (26.23%-62.17%) with reduction in turn counts (29.07%- 42.2%) and peristaltic speed (31.38%-42.22%) amongst exposed groups as to control. The present work shows behavioral alterations due to risperidone exposure (50 µM) in C. elegans is in a time-dependent manner. The study concludes that risperidone exposure in C. elegans produces toxic effects with time, possibly caused by antagonizing other receptors apart from serotonin (5-H2T) and dopamine (D2) adding to its expected pharmacological effects.
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Key Words
- 5-H2T
- 5-HT, 5-hydroxytryptamine
- ADF, Amphid Neuron
- APDs, Antipsychotic drugs
- Antipsychotic drugs
- Behavioral alteration
- C, Control Group
- C-0h, Control Group at 0 h
- C-10h, Control Group at 10 h
- C-12h, Control Group at 12 h. E-2h, Exposure Group at 2 h
- C-2h, Control Group at 2 h
- C-4h, Control Group at 4 h
- C-6h, Control Group at 6 h
- C-8h, Control Group at 8 h
- C. elegans
- C. elegans, Caenorhabditis elegans
- D2
- D2, Dopamine Receptor 2
- E, Exposed Group
- E-10h, Exposure Group at ten
- E-12h, Exposure Group at 12 h
- E-4h, Exposure Group at 4 h
- E-6h, Exposure Group at 6 h
- E-8h, Exposure Group at 8 h
- E. coli, Escherichia coli BOD-Biochemical Oxygen Demand
- GPR, G coupled Protein Receptor
- HSN, Hermaphrodite Specific Neuron
- Min., Minutes
- N2 Wild type
- NSM, Neurosecretory Motor Neuron
- Peristaltic speed
- Pharyngeal pumping
- Reversals
- Risperidone
- SD, Standard Deviation
- SDA, Serotonin Dopamine Antagonist
- Turn counts
- omega bends
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Affiliation(s)
- Aaditya Vikram Gaur
- Laboratory of Analytical & Molecular Toxicology (Forensic Chemistry & Toxicology Laboratory), School of Forensic Science, National Forensic Sciences University, Sector 09, Gandhinagar 382007, Gujarat, India
- Forensic Science Laboratory, Kirumampakkam, Puducherry 607402, India
| | - Rakhi Agarwal
- Laboratory of Analytical & Molecular Toxicology (Forensic Chemistry & Toxicology Laboratory), School of Forensic Science, National Forensic Sciences University, Sector 09, Gandhinagar 382007, Gujarat, India
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11
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Rahmani A, Chew YL. Investigating the molecular mechanisms of learning and memory using Caenorhabditis elegans. J Neurochem 2021; 159:417-451. [PMID: 34528252 DOI: 10.1111/jnc.15510] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/15/2021] [Accepted: 09/08/2021] [Indexed: 11/30/2022]
Abstract
Learning is an essential biological process for survival since it facilitates behavioural plasticity in response to environmental changes. This process is mediated by a wide variety of genes, mostly expressed in the nervous system. Many studies have extensively explored the molecular and cellular mechanisms underlying learning and memory. This review will focus on the advances gained through the study of the nematode Caenorhabditis elegans. C. elegans provides an excellent system to study learning because of its genetic tractability, in addition to its invariant, compact nervous system (~300 neurons) that is well-characterised at the structural level. Importantly, despite its compact nature, the nematode nervous system possesses a high level of conservation with mammalian systems. These features allow the study of genes within specific sensory-, inter- and motor neurons, facilitating the interrogation of signalling pathways that mediate learning via defined neural circuits. This review will detail how learning and memory can be studied in C. elegans through behavioural paradigms that target distinct sensory modalities. We will also summarise recent studies describing mechanisms through which key molecular and cellular pathways are proposed to affect associative and non-associative forms of learning.
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Affiliation(s)
- Aelon Rahmani
- Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
| | - Yee Lian Chew
- Flinders Health and Medical Research Institute, Flinders University, Adelaide, South Australia, Australia
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12
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Abstract
Caenorhabditis elegans' behavioral states, like those of other animals, are shaped by its immediate environment, its past experiences, and by internal factors. We here review the literature on C. elegans behavioral states and their regulation. We discuss dwelling and roaming, local and global search, mate finding, sleep, and the interaction between internal metabolic states and behavior.
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Affiliation(s)
- Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - David M Raizen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Young-Jai You
- Division of Biological Science, Graduate School of Science, Nagoya University, 464-8602, Japan
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13
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Abstract
The serotonergic modulation of feeding behaviour has been intensively studied in several invertebrate groups, including Arthropoda, Annelida, Nematoda and Mollusca. These studies offer comparative information on feeding regulation across divergent phyla and also provide general insights into the neural control of feeding. Specifically, model invertebrates are ideal for parsing feeding behaviour into component parts and examining the underlying mechanisms at the levels of biochemical pathways, single cells and identified neural circuitry. Research has found that serotonin is crucial during certain phases of feeding behaviour, especially movements directly underlying food intake, but inessential during other phases. In addition, while the serotonin system can be manipulated systemically in many animals, invertebrate model organisms also allow manipulations at the level of single cells and molecules, revealing limited and precise serotonergic actions. The latter highlight the importance of local versus global modulatory effects of serotonin, a potentially significant consideration for drug and pesticide design.
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Affiliation(s)
- Ann Jane Tierney
- Neuroscience Program, Psychological and Brain Sciences, Colgate University, Hamilton, NY, USA
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14
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O'Donnell MP, Fox BW, Chao PH, Schroeder FC, Sengupta P. A neurotransmitter produced by gut bacteria modulates host sensory behaviour. Nature 2020; 583:415-420. [PMID: 32555456 PMCID: PMC7853625 DOI: 10.1038/s41586-020-2395-5] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 03/27/2020] [Indexed: 12/18/2022]
Abstract
Animals coexist in commensal, pathogenic or mutualistic relationships with complex communities of diverse organisms, including microorganisms1. Some bacteria produce bioactive neurotransmitters that have previously been proposed to modulate nervous system activity and behaviours of their hosts2,3. However, the mechanistic basis of this microbiota-brain signalling and its physiological relevance are largely unknown. Here we show that in Caenorhabditis elegans, the neuromodulator tyramine produced by commensal Providencia bacteria, which colonize the gut, bypasses the requirement for host tyramine biosynthesis and manipulates a host sensory decision. Bacterially produced tyramine is probably converted to octopamine by the host tyramine β-hydroxylase enzyme. Octopamine, in turn, targets the OCTR-1 octopamine receptor on ASH nociceptive neurons to modulate an aversive olfactory response. We identify the genes that are required for tyramine biosynthesis in Providencia, and show that these genes are necessary for the modulation of host behaviour. We further find that C. elegans colonized by Providencia preferentially select these bacteria in food choice assays, and that this selection bias requires bacterially produced tyramine and host octopamine signalling. Our results demonstrate that a neurotransmitter produced by gut bacteria mimics the functions of the cognate host molecule to override host control of a sensory decision, and thereby promotes fitness of both the host and the microorganism.
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Affiliation(s)
| | - Bennett W Fox
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Pin-Hao Chao
- Department of Biology, Brandeis University, Waltham, MA, USA
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, MA, USA.
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15
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Ishita Y, Chihara T, Okumura M. Serotonergic modulation of feeding behavior in Caenorhabditis elegans and other related nematodes. Neurosci Res 2020; 154:9-19. [DOI: 10.1016/j.neures.2019.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/10/2019] [Accepted: 04/22/2019] [Indexed: 10/26/2022]
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16
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Das S, Ooi FK, Cruz Corchado J, Fuller LC, Weiner JA, Prahlad V. Serotonin signaling by maternal neurons upon stress ensures progeny survival. eLife 2020; 9:e55246. [PMID: 32324136 PMCID: PMC7237211 DOI: 10.7554/elife.55246] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 04/22/2020] [Indexed: 01/03/2023] Open
Abstract
Germ cells are vulnerable to stress. Therefore, how organisms protect their future progeny from damage in a fluctuating environment is a fundamental question in biology. We show that in Caenorhabditis elegans, serotonin released by maternal neurons during stress ensures the viability and stress resilience of future offspring. Serotonin acts through a signal transduction pathway conserved between C. elegans and mammalian cells to enable the transcription factor HSF1 to alter chromatin in soon-to-be fertilized germ cells by recruiting the histone chaperone FACT, displacing histones, and initiating protective gene expression. Without serotonin release by maternal neurons, FACT is not recruited by HSF1 in germ cells, transcription occurs but is delayed, and progeny of stressed C. elegans mothers fail to complete development. These studies uncover a novel mechanism by which stress sensing by neurons is coupled to transcription response times of germ cells to protect future offspring.
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Affiliation(s)
- Srijit Das
- Department of Biology, Aging Mind and Brain InitiativeIowa CityUnited States
| | - Felicia K Ooi
- Department of Biology, Aging Mind and Brain InitiativeIowa CityUnited States
| | | | | | - Joshua A Weiner
- Department of BiologyIowa CityUnited States
- Iowa Neuroscience InstituteIowa CityUnited States
| | - Veena Prahlad
- Department of Biology, Aging Mind and Brain InitiativeIowa CityUnited States
- Department of BiologyIowa CityUnited States
- Iowa Neuroscience InstituteIowa CityUnited States
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17
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Cruz-Corchado J, Ooi FK, Das S, Prahlad V. Global Transcriptome Changes That Accompany Alterations in Serotonin Levels in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2020; 10:1225-1246. [PMID: 31996358 PMCID: PMC7144078 DOI: 10.1534/g3.120.401088] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/25/2020] [Indexed: 11/18/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT), is a phylogenetically ancient molecule best characterized as a neurotransmitter that modulates multiple aspects of mood and social cognition. The roles that 5-HT plays in normal and abnormal behavior are not fully understood but have been posited to be due to its common function as a 'defense signal'. However, 5-HT levels also systemically impact cell physiology, modulating cell division, migration, apoptosis, mitochondrial biogenesis, cellular metabolism and differentiation. Whether these diverse cellular effects of 5-HT also share a common basis is unclear. C. elegans provides an ideal system to interrogate the systemic effects of 5-HT, since lacking a blood-brain barrier, 5-HT synthesized and released by neurons permeates the organism to modulate neuronal as well as non-neuronal cells throughout the body. Here we used RNA-Seq to characterize the systemic changes in gene expression that occur in C. elegans upon altering 5-HT levels, and compared the transcriptomes to published datasets. We find that an acute increase in 5-HT is accompanied by a global decrease in gene expression levels, upregulation of genes involved in stress pathways, changes that significantly correlate with the published transcriptomes of animals that have activated defense and immune responses, and an increase in levels of phosphorylated eukaryotic initiation factor, eIF2α. In 5-HT deficient animals lacking tryptophan hydroxylase (tph-1(mg280)II) there is a net increase in gene expression, with an overrepresentation of genes related to development and chromatin. Surprisingly, the transcriptomes of animals with acute increases in 5-HT levels, and 5-HT deficiency do not overlap with transcriptomes of mutants with whom they share striking physiological resemblance. These studies are the first to catalog systemic transcriptome changes that occur upon alterations in 5-HT levels. They further show that in C. elegans changes in gene expression upon altering 5-HT levels, and changes in physiology, are not directly correlated.
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Affiliation(s)
- Johnny Cruz-Corchado
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
| | - Felicia K Ooi
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
| | - Srijit Das
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
| | - Veena Prahlad
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
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18
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Fueser H, Mueller MT, Weiss L, Höss S, Traunspurger W. Ingestion of microplastics by nematodes depends on feeding strategy and buccal cavity size. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 255:113227. [PMID: 31574393 DOI: 10.1016/j.envpol.2019.113227] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 06/10/2023]
Abstract
Microplastics are hardly biodegradable and thus accumulate rather than decompose in the environment. Due to sedimentation processes, meiobenthic fauna is exposed to microplastics. Within the meiofauna, nematodes are a very abundant taxon and occupy an important position in benthic food webs by connecting lower and higher trophic levels. However, the key determinants of the uptake of microplastics by freshwater nematodes are still unknown. To investigate the bioaccessibility of microplastics for nematodes, we performed single- and multi-species ingestion experiments in which the ability of seven nematode species (six bacterial and one fungal feeder), diverse in their buccal cavity morphology (1.3-10.5 μm), to ingest fluorescence-labelled polystyrene (PS) beads along with their natural diet was examined. Applied beads sizes (0.5, 1.0, 3.0 and 6.0 μm), exposure time (4, 24 and 72 h) and concentration (3 × 106 PS beads ml-1 and 107 PS beads ml-1) were varied. Ingested beads were localized and quantified via fluorescence microscopy in the nematodes. In contrast to fungal-feeding nematode species with a stylet, bacterial-feeding species ingested 0.5- and 1.0-μm PS beads with up to 249 and 255 beads after 24 h, respectively. Microplastics ≥0.5 μm could only be ingested and transported into the gastrointestinal tract, if the buccal cavities were considerably (>1.3 times) larger than the beads. At concentrations of 107 PS beads ml-1 ingestion rates were influenced by exposure time and PS bead concentration. In case of a known microplastic size distribution in the environment, predictions on the potential ingestion for nematode communities can be made based on the feeding type composition and the size of their buccal cavities.
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Affiliation(s)
- Hendrik Fueser
- Bielefeld University, Animal Ecology, Konsequenz 45, 33615 Bielefeld, Germany.
| | | | - Linette Weiss
- Bielefeld University, Animal Ecology, Konsequenz 45, 33615 Bielefeld, Germany
| | - Sebastian Höss
- Bielefeld University, Animal Ecology, Konsequenz 45, 33615 Bielefeld, Germany; Ecossa, Giselastr. 6, 82319 Starnberg, Germany
| | - Walter Traunspurger
- Bielefeld University, Animal Ecology, Konsequenz 45, 33615 Bielefeld, Germany
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19
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Zhou JJ, Chun L, Liu JF. A Comprehensive Understanding of Dietary Effects on C. elegans Physiology. Curr Med Sci 2019; 39:679-684. [PMID: 31612382 DOI: 10.1007/s11596-019-2091-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/14/2019] [Indexed: 02/07/2023]
Abstract
Diet has been shown to play an important role in human physiology. It is a predominant exogenous factor regulating the composition of gut microbiota, and dietary intervention holds promise for treatment of diseases such as obesity, type 2 diabetes, and malnutrition. Furthermore, it was reported that diet has significant effects on physiological processes of C. elegans, including reproduction, fat storage, and aging. To reveal novel signaling pathways responsive to different diets, C. elegans and its bacterial diet were used as an interspecies model system to mimic the interaction between host and gut microbiota. Most signaling pathways identified in C. elegans are highly conserved across different species, including humans. A better understanding of these pathways can, therefore, help to develop interventions for human diseases. In this article, we summarize recent achievements on molecular mechanisms underlying the response of C. elegans to different diets and discuss their relevance to human health.
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Affiliation(s)
- Jie-Jun Zhou
- Collaborative Innovation Center for Brain Science, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Lei Chun
- Collaborative Innovation Center for Brain Science, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Jian-Feng Liu
- Collaborative Innovation Center for Brain Science, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China.
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20
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Reciprocal modulation of 5-HT and octopamine regulates pumping via feedforward and feedback circuits in C. elegans. Proc Natl Acad Sci U S A 2019; 116:7107-7112. [PMID: 30872487 PMCID: PMC6452730 DOI: 10.1073/pnas.1819261116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Physiological regulation and behavior depend less on neurons than on neuronal circuits. Neurosignal integration is the basis of neurocircuit function. The modalities of neuroinformation integration are evolutionarily conserved in animals and humans. Here, we identified two modalities of neurosignal integration in two different circuits by which serotonergic ADFs regulate pharyngeal pumping in Caenorhabditis elegans: disinhibition in a feedforward circuit consisting of ADF, RIC, and SIA neurons and disexcitation, a modality of neurosignal integration suggested by this study, in a feedback circuit consisting of ADF, RIC, AWB, and ADF neurons. Feeding is vital for animal survival and is tightly regulated by the endocrine and nervous systems. To study the mechanisms of humoral regulation of feeding behavior, we investigated serotonin (5-HT) and octopamine (OA) signaling in Caenorhabditis elegans, which uses pharyngeal pumping to ingest bacteria into the gut. We reveal that a cross-modulation mechanism between 5-HT and OA, which convey feeding and fasting signals, respectively, mainly functions in regulating the pumping and secretion of both neuromodulators via ADF/RIC/SIA feedforward neurocircuit (consisting of ADF, RIC, and SIA neurons) and ADF/RIC/AWB/ADF feedback neurocircuit (consisting of ADF, RIC, AWB, and ADF neurons) under conditions of food supply and food deprivation, respectively. Food supply stimulates food-sensing ADFs to release more 5-HT, which augments pumping via inhibiting OA secretion by RIC interneurons and, thus, alleviates pumping suppression by OA-activated SIA interneurons/motoneurons. In contrast, nutrient deprivation stimulates RICs to secrete OA, which suppresses pumping via activating SIAs and maintains basal pumping and 5-HT production activity through excitation of ADFs relayed by AWB sensory neurons. Notably, the feedforward and feedback circuits employ distinct modalities of neurosignal integration, namely, disinhibition and disexcitation, respectively.
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21
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Calahorro F, Keefe F, Dillon J, Holden-Dye L, O'Connor V. Neuroligin tuning of pharyngeal pumping reveals extrapharyngeal modulation of feeding in Caenorhabditis elegans. ACTA ACUST UNITED AC 2019; 222:jeb.189423. [PMID: 30559302 DOI: 10.1242/jeb.189423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 12/07/2018] [Indexed: 01/16/2023]
Abstract
The integration of distinct sensory modalities is essential for behavioural decision making. In C aenorhabditis elegans, this process is coordinated by neural circuits that integrate sensory cues from the environment to generate an appropriate behaviour at the appropriate output muscles. Food is a multimodal cue that impacts the microcircuits to modulate feeding and foraging drivers at the level of the pharyngeal and body wall muscle, respectively. When food triggers an upregulation in pharyngeal pumping, it allows the effective ingestion of food. Here, we show that a C elegans mutant in the single gene orthologous to human neuroligins, nlg-1, is defective in food-induced pumping. This was not due to an inability to sense food, as nlg-1 mutants were not defective in chemotaxis towards bacteria. In addition, we found that neuroligin is widely expressed in the nervous system, including AIY, ADE, ALA, URX and HSN neurons. Interestingly, despite the deficit in pharyngeal pumping, neuroligin was not expressed within the pharyngeal neuromuscular network, which suggests an extrapharyngeal regulation of this circuit. We resolved electrophysiologically the neuroligin contribution to the pharyngeal circuit by mimicking food-dependent pumping and found that the nlg-1 phenotype is similar to mutants impaired in GABAergic and/or glutamatergic signalling. We suggest that neuroligin organizes extrapharyngeal circuits that regulate the pharynx. These observations based on the molecular and cellular determinants of feeding are consistent with the emerging role of neuroligin in discretely impacting functional circuits underpinning complex behaviours.
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Affiliation(s)
- Fernando Calahorro
- Biological Sciences, Building 85, University of Southampton, Southampton SO17 1BJ, UK
| | - Francesca Keefe
- Biological Sciences, Building 85, University of Southampton, Southampton SO17 1BJ, UK
| | - James Dillon
- Biological Sciences, Building 85, University of Southampton, Southampton SO17 1BJ, UK
| | - Lindy Holden-Dye
- Biological Sciences, Building 85, University of Southampton, Southampton SO17 1BJ, UK
| | - Vincent O'Connor
- Biological Sciences, Building 85, University of Southampton, Southampton SO17 1BJ, UK
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22
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Gottschling DC, Döring F. Is C. elegans a suitable model for nutritional science? GENES AND NUTRITION 2019; 14:1. [PMID: 30651890 PMCID: PMC6327375 DOI: 10.1186/s12263-018-0625-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 12/05/2018] [Indexed: 02/14/2023]
Abstract
The suitability of C. elegans as a model for the question of nutritional science is a controversial topic. The discussion makes clear that C. elegans is its own best model for revealing, via genetic approaches, biological principles of nutritional behavior, and the biochemical function of vitamins. In this case, the model has a discovery function. Worm research serves also in the identification of nutrition-dependent pathways that could be used for novel approaches in human nutritional studies. This heuristic function of the model guides the applied nutrition research in an innovative direction. Since the nutrition and metabolism for the worm and man differ from each other somewhat strongly, results of nutritional studies in C. elegans are not directly applicable to human nutrition. In general, the C. elegans model is primarily appropriate for explaining the causality of general species’ nutritional phenotypes. Experience tells us that the analysis of drastic nutritional phenotypes in C. elegans has the potential to enrich the canon of knowledge of nutritional science.
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Affiliation(s)
- Dieter-Christian Gottschling
- Department of Human Nutrition and Food Research, University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany
| | - Frank Döring
- Department of Human Nutrition and Food Research, University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany
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23
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Koelle MR. Neurotransmitter signaling through heterotrimeric G proteins: insights from studies in C. elegans. WORMBOOK : THE ONLINE REVIEW OF C. ELEGANS BIOLOGY 2018; 2018:1-52. [PMID: 26937633 PMCID: PMC5010795 DOI: 10.1895/wormbook.1.75.2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Neurotransmitters signal via G protein coupled receptors (GPCRs) to modulate activity of neurons and muscles. C. elegans has ∼150 G protein coupled neuropeptide receptor homologs and 28 additional GPCRs for small-molecule neurotransmitters. Genetic studies in C. elegans demonstrate that neurotransmitters diffuse far from their release sites to activate GPCRs on distant cells. Individual receptor types are expressed on limited numbers of cells and thus can provide very specific regulation of an individual neural circuit and behavior. G protein coupled neurotransmitter receptors signal principally via the three types of heterotrimeric G proteins defined by the G alpha subunits Gαo, Gαq, and Gαs. Each of these G alpha proteins is found in all neurons plus some muscles. Gαo and Gαq signaling inhibit and activate neurotransmitter release, respectively. Gαs signaling, like Gαq signaling, promotes neurotransmitter release. Many details of the signaling mechanisms downstream of Gαq and Gαs have been delineated and are consistent with those of their mammalian orthologs. The details of the signaling mechanism downstream of Gαo remain a mystery. Forward genetic screens in C. elegans have identified new molecular components of neural G protein signaling mechanisms, including Regulators of G protein Signaling (RGS proteins) that inhibit signaling, a new Gαq effector (the Trio RhoGEF domain), and the RIC-8 protein that is required for neuronal Gα signaling. A model is presented in which G proteins sum up the variety of neuromodulator signals that impinge on a neuron to calculate its appropriate output level.
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Affiliation(s)
- Michael R Koelle
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven CT 06520 USA
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24
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Weeks JC, Robinson KJ, Lockery SR, Roberts WM. Anthelmintic drug actions in resistant and susceptible C. elegans revealed by electrophysiological recordings in a multichannel microfluidic device. Int J Parasitol Drugs Drug Resist 2018; 8:607-628. [PMID: 30503202 PMCID: PMC6287544 DOI: 10.1016/j.ijpddr.2018.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/17/2018] [Accepted: 10/18/2018] [Indexed: 12/22/2022]
Abstract
Many anthelmintic drugs used to treat parasitic nematode infections target proteins that regulate electrical activity of neurons and muscles: ion channels (ICs) and neurotransmitter receptors (NTRs). Perturbation of IC/NTR function disrupts worm behavior and can lead to paralysis, starvation, immune attack and expulsion. Limitations of current anthelmintics include a limited spectrum of activity across species and the threat of drug resistance, highlighting the need for new drugs for human and veterinary medicine. Although ICs/NTRs are valuable anthelmintic targets, electrophysiological recordings are not commonly included in drug development pipelines. We designed a medium-throughput platform for recording electropharyngeograms (EPGs)-the electrical signals emitted by muscles and neurons of the pharynx during pharyngeal pumping (feeding)-in Caenorhabditis elegans and parasitic nematodes. The current study in C. elegans expands previous work in several ways. Detecting anthelmintic bioactivity in drugs, compounds or natural products requires robust, sustained pharyngeal pumping under baseline conditions. We generated concentration-response curves for stimulating pumping by perfusing 8-channel microfluidic devices (chips) with the neuromodulator serotonin, or with E. coli bacteria (C. elegans' food in the laboratory). Worm orientation in the chip (head-first vs. tail-first) affected the response to E. coli but not to serotonin. Using a panel of anthelmintics-ivermectin, levamisole and piperazine-targeting different ICs/NTRs, we determined the effects of concentration and treatment duration on EPG activity, and successfully distinguished control (N2) and drug-resistant worms (avr-14; avr-15; glc-1, unc-38 and unc-49). EPG recordings detected anthelmintic activity of drugs that target ICs/NTRs located in the pharynx as well as at extra-pharyngeal sites. A bus-8 mutant with enhanced permeability was more sensitive than controls to drug treatment. These results provide a useful framework for investigators who would like to more easily incorporate electrophysiology as a routine component of their anthelmintic research workflow.
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Affiliation(s)
- Janis C Weeks
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - Kristin J Robinson
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - Shawn R Lockery
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - William M Roberts
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
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25
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Aonuma H, Totani Y, Sakakibara M, Lukowiak K, Ito E. Comparison of brain monoamine content in three populations of Lymnaea that correlates with taste-aversive learning ability. Biophys Physicobiol 2018; 15:129-135. [PMID: 29955564 PMCID: PMC6018436 DOI: 10.2142/biophysico.15.0_129] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 04/20/2018] [Indexed: 12/01/2022] Open
Abstract
To find a causal mechanism of learning and memory is a heuristically important topic in neuroscience. In the pond snail Lymnaea stagnalis, the following experimental facts have accrued regarding a classical conditioning procedure known as conditioned taste aversion (CTA): (1) one-day food-deprived Dutch snails have superior CTA memory formation; (2) the one-day food-deprived snails have a low monoamine content (e.g., serotonin, dopamine, octopamine) in their central nervous system (CNS); (3) fed or five-day food-deprived snails have poorer CTA memory and a higher monoamine content; (4) the Dutch snails form better CTA memory than the Canadian TC1 strain; and, (5) the F1 cross snails between the Dutch and Canadian TC1 strains also form poor CTA memory. Here, in one-day food-deprived snails, we measured the monoamine content in the CNSs of the 3 populations. In most instances, the monoamine content of the Dutch strain was lower than in the other two populations. The F1 cross snails had the highest monoamine content. A lower monoamine content is correlated with the better CTA memory formation.
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Affiliation(s)
- Hitoshi Aonuma
- Research Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 060-0811, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Yuki Totani
- Department of Biology, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Manabu Sakakibara
- Research Organization for Nano and Life Innovation, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Ken Lukowiak
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Etsuro Ito
- Department of Biology, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.,Research Organization for Nano and Life Innovation, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.,WASEDA Bioscience Research Institute in Singapore, 138667, Singapore.,Graduate Institute of Medicine and Center for Stem Cell Research, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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26
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Influence of Pig Farming on the Human Nasal Microbiota: Key Role of Airborne Microbial Communities. Appl Environ Microbiol 2018; 84:AEM.02470-17. [PMID: 29330190 PMCID: PMC5835734 DOI: 10.1128/aem.02470-17] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
It has been hypothesized that the environment can influence the composition of the nasal microbiota. However, the direct influence of pig farming on the anterior and posterior nasal microbiota is unknown. Using a cross-sectional design, pig farms (n = 28) were visited in 2014 to 2015, and nasal swabs from 43 pig farmers and 56 pigs, as well as 27 air samples taken in the vicinity of the pig enclosures, were collected. As controls, nasal swabs from 17 cow farmers and 26 non-animal-exposed individuals were also included. Analyses of the microbiota were performed based on 16S rRNA amplicon sequencing and the DADA2 pipeline to define sequence variants (SVs). We found that pig farming is strongly associated with specific microbial signatures (including alpha- and beta-diversity), which are reflected in the microbiota of the human nose. Furthermore, the microbial communities were more similar within the same farm compared to between the different farms, indicating a specific microbiota pattern for each pig farm. In total, there were 82 SVs that occurred significantly more abundantly in samples from pig farms than from cow farmers and nonexposed individuals (i.e., the core pig farm microbiota). Of these, nine SVs were significantly associated with the posterior part of the human nose. The results strongly indicate that pig farming is associated with a distinct human nose microbiota. Finally, the community structures derived by the DADA2 pipeline showed an excellent agreement with the outputs of the mothur pipeline which was revealed by procrustes analyses. IMPORTANCE The knowledge about the influence of animal keeping on the human microbiome is important. Previous research has shown that pets significantly affect the microbial communities of humans. However, the effect of animal farming on the human microbiota is less clear, although it is known that the air at farms and, in particular, at pig farms is charged with large amounts of dust, bacteria, and fungi. In this study, we simultaneously investigated the nasal microbiota of pigs, humans, and the environment at pig farms. We reveal an enormous impact of pig farming on the human nasal microbiota which is far more pronounced compared to cow farming. In addition, we analyzed the airborne microbiota and found significant associations suggesting an animal-human transmission of the microbiota within pig farms. We also reveal that microbial patterns are farm specific, suggesting that the environment influences animals and humans in a similar manner.
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27
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Scaplen KM, Kaun KR. Reward from bugs to bipeds: a comparative approach to understanding how reward circuits function. J Neurogenet 2017; 30:133-48. [PMID: 27328845 PMCID: PMC4926782 DOI: 10.1080/01677063.2016.1180385] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In a complex environment, animals learn from their responses to stimuli and events. Appropriate response to reward and punishment can promote survival, reproduction and increase evolutionary fitness. Interestingly, the neural processes underlying these responses are remarkably similar across phyla. In all species, dopamine is central to encoding reward and directing motivated behaviors, however, a comprehensive understanding of how circuits encode reward and direct motivated behaviors is still lacking. In part, this is a result of the sheer diversity of neurons, the heterogeneity of their responses and the complexity of neural circuits within which they are found. We argue that general features of reward circuitry are common across model organisms, and thus principles learned from invertebrate model organisms can inform research across species. In particular, we discuss circuit motifs that appear to be functionally equivalent from flies to primates. We argue that a comparative approach to studying and understanding reward circuit function provides a more comprehensive understanding of reward circuitry, and informs disorders that affect the brain’s reward circuitry.
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Affiliation(s)
- Kristin M Scaplen
- a Department of Neuroscience , Brown University , Providence , RI , USA
| | - Karla R Kaun
- a Department of Neuroscience , Brown University , Providence , RI , USA
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28
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Gracida X, Dion MF, Harris G, Zhang Y, Calarco JA. An Elongin-Cullin-SOCS Box Complex Regulates Stress-Induced Serotonergic Neuromodulation. Cell Rep 2017; 21:3089-3101. [PMID: 29241538 PMCID: PMC6283282 DOI: 10.1016/j.celrep.2017.11.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/15/2017] [Accepted: 11/11/2017] [Indexed: 02/07/2023] Open
Abstract
Neuromodulatory cells transduce environmental information into long-lasting behavioral responses. However, the mechanisms governing how neuronal cells influence behavioral plasticity are difficult to characterize. Here, we adapted the translating ribosome affinity purification (TRAP) approach in C. elegans to profile ribosome-associated mRNAs from three major tissues and the neuromodulatory dopaminergic and serotonergic cells. We identified elc-2, an Elongin C ortholog, specifically expressed in stress-sensing amphid neuron dual ciliated sensory ending (ADF) serotonergic sensory neurons, and we found that it plays a role in mediating a long-lasting change in serotonin-dependent feeding behavior induced by heat stress. We demonstrate that ELC-2 and the von Hippel-Lindau protein VHL-1, components of an Elongin-Cullin-SOCS box (ECS) E3 ubiquitin ligase, modulate this behavior after experiencing stress. Also, heat stress induces a transient redistribution of ELC-2, becoming more nuclearly enriched. Together, our results demonstrate dynamic regulation of an E3 ligase and a role for an ECS complex in neuromodulation and control of lasting behavioral states.
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Affiliation(s)
- Xicotencatl Gracida
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Michael F Dion
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Gareth Harris
- Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Yun Zhang
- Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
| | - John A Calarco
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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Stern S, Kirst C, Bargmann CI. Neuromodulatory Control of Long-Term Behavioral Patterns and Individuality across Development. Cell 2017; 171:1649-1662.e10. [DOI: 10.1016/j.cell.2017.10.041] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 09/10/2017] [Accepted: 10/24/2017] [Indexed: 12/20/2022]
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Serotonin Drives Predatory Feeding Behavior via Synchronous Feeding Rhythms in the Nematode Pristionchus pacificus. G3-GENES GENOMES GENETICS 2017; 7:3745-3755. [PMID: 28903981 PMCID: PMC5677172 DOI: 10.1534/g3.117.300263] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Feeding behaviors in a wide range of animals are regulated by the neurotransmitter serotonin, although the exact neural circuits and associated mechanism are often unknown. The nematode Pristionchus pacificus can kill other nematodes by opening prey cuticles with movable teeth. Previous studies showed that exogenous serotonin treatment induces a predatory-like tooth movement and slower pharyngeal pumping in the absence of prey; however, physiological functions of serotonin during predation and other behaviors in P. pacificus remained completely unknown. Here, we investigate the roles of serotonin by generating mutations in Ppa-tph-1 and Ppa-bas-1, two key serotonin biosynthesis enzymes, and by genetic ablation of pharynx-associated serotonergic neurons. Mutations in Ppa-tph-1 reduced the pharyngeal pumping rate during bacterial feeding compared with wild-type. Moreover, the loss of serotonin or a subset of serotonergic neurons decreased the success of predation, but did not abolish the predatory feeding behavior completely. Detailed analysis using a high-speed camera revealed that the elimination of serotonin or the serotonergic neurons disrupted the timing and coordination of predatory tooth movement and pharyngeal pumping. This loss of synchrony significantly reduced the efficiency of successful predation events. These results suggest that serotonin has a conserved role in bacterial feeding and in addition drives the feeding rhythm of predatory behavior in Pristionchus.
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Ooi FK, Prahlad V. Olfactory experience primes the heat shock transcription factor HSF-1 to enhance the expression of molecular chaperones in C. elegans. Sci Signal 2017; 10:10/501/eaan4893. [PMID: 29042483 DOI: 10.1126/scisignal.aan4893] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Learning, a process by which animals modify their behavior as a result of experience, enables organisms to synthesize information from their surroundings to acquire resources and avoid danger. We showed that a previous encounter with only the odor of pathogenic bacteria prepared Caenorhabditis elegans to survive exposure to the pathogen by increasing the heat shock factor 1 (HSF-1)-dependent expression of genes encoding molecular chaperones. Experience-mediated enhancement of chaperone gene expression required serotonin, which primed HSF-1 to enhance the expression of molecular chaperone genes by promoting its localization to RNA polymerase II-enriched nuclear loci, even before transcription occurred. However, HSF-1-dependent chaperone gene expression was stimulated only if and when animals encountered the pathogen. Thus, learning equips C. elegans to better survive environmental dangers by preemptively and specifically initiating transcriptional mechanisms throughout the whole organism that prepare the animal to respond rapidly to proteotoxic agents. These studies provide one plausible basis for the protective role of environmental enrichment in disease.
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Affiliation(s)
- Felicia K Ooi
- Department of Biology, Aging Mind and Brain Initiative, 143 Biology Building East, 338 BBE, University of Iowa, Iowa City, IA 52242, USA
| | - Veena Prahlad
- Department of Biology, Aging Mind and Brain Initiative, 143 Biology Building East, 338 BBE, University of Iowa, Iowa City, IA 52242, USA.
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Sanders J, Scholz M, Merutka I, Biron D. Distinct unfolded protein responses mitigate or mediate effects of nonlethal deprivation of C. elegans sleep in different tissues. BMC Biol 2017; 15:67. [PMID: 28844202 PMCID: PMC5572162 DOI: 10.1186/s12915-017-0407-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/24/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Disrupting sleep during development leads to lasting deficits in chordates and arthropods. To address lasting impacts of sleep deprivation in Caenorhabditis elegans, we established a nonlethal deprivation protocol. RESULTS Deprivation triggered protective insulin-like signaling and two unfolded protein responses (UPRs): the mitochondrial (UPRmt) and the endoplasmic reticulum (UPRER) responses. While the latter is known to be triggered by sleep deprivation in rodent and insect brains, the former was not strongly associated with sleep deprivation previously. We show that deprivation results in a feeding defect when the UPRmt is deficient and in UPRER-dependent germ cell apoptosis. In addition, when the UPRER is deficient, deprivation causes excess twitching in vulval muscles, mirroring a trend caused by loss of egg-laying command neurons. CONCLUSIONS These data show that nonlethal deprivation of C. elegans sleep causes proteotoxic stress. Unless mitigated, distinct types of deprivation-induced proteotoxicity can lead to anatomically and genetically separable lasting defects. The relative importance of different UPRs post-deprivation likely reflects functional, developmental, and genetic differences between the respective tissues and circuits.
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Affiliation(s)
- Jarred Sanders
- Genetics, Genomics, and Systems Biology, The University of Chicago, Chicago, IL, 60637, USA.
| | - Monika Scholz
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - Ilaria Merutka
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - David Biron
- Genetics, Genomics, and Systems Biology, The University of Chicago, Chicago, IL, 60637, USA.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA.,Department of Physics, The University of Chicago, Chicago, IL, 60637, USA
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Stochastic feeding dynamics arise from the need for information and energy. Proc Natl Acad Sci U S A 2017; 114:9261-9266. [PMID: 28802256 DOI: 10.1073/pnas.1703958114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Animals regulate their food intake in response to the available level of food. Recent observations of feeding dynamics in small animals showed feeding patterns of bursts and pauses, but their function is unknown. Here, we present a data-driven decision-theoretical model of feeding in Caenorhabditis elegans Our central assumption is that food intake serves a dual purpose: to gather information about the external food level and to ingest food when the conditions are good. The model recapitulates experimentally observed feeding patterns. It naturally implements trade-offs between speed versus accuracy and exploration versus exploitation in responding to a dynamic environment. We find that the model predicts three distinct regimes in responding to a dynamical environment, with a transition region where animals respond stochastically to periodic signals. This stochastic response accounts for previously unexplained experimental data.
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Antagonistic Serotonergic and Octopaminergic Neural Circuits Mediate Food-Dependent Locomotory Behavior in Caenorhabditis elegans. J Neurosci 2017; 37:7811-7823. [PMID: 28698386 DOI: 10.1523/jneurosci.2636-16.2017] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 05/18/2017] [Accepted: 07/01/2017] [Indexed: 11/21/2022] Open
Abstract
Biogenic amines are conserved signaling molecules that link food cues to behavior and metabolism in a wide variety of organisms. In the nematode Caenorhabditis elegans, the biogenic amines serotonin (5-HT) and octopamine regulate a number of food-related behaviors. Using a novel method for long-term quantitative behavioral imaging, we show that 5-HT and octopamine jointly influence locomotor activity and quiescence in feeding and fasting hermaphrodites, and we define the neural circuits through which this modulation occurs. We show that 5-HT produced by the ADF neurons acts via the SER-5 receptor in muscles and neurons to suppress quiescent behavior and promote roaming in fasting worms, whereas 5-HT produced by the NSM neurons acts on the MOD-1 receptor in AIY neurons to promote low-amplitude locomotor behavior characteristic of well fed animals. Octopamine, produced by the RIC neurons, acts via SER-3 and SER-6 receptors in SIA neurons to promote roaming behaviors characteristic of fasting animals. We find that 5-HT signaling is required for animals to assume food-appropriate behavior, whereas octopamine signaling is required for animals to assume fasting-appropriate behavior. The requirement for both neurotransmitters in both the feeding and fasting states enables increased behavioral adaptability. Our results define the molecular and neural pathways through which parallel biogenic amine signaling tunes behavior appropriately to nutrient conditions.SIGNIFICANCE STATEMENT Animals adjust behavior in response to environmental changes, such as fluctuations in food abundance, to maximize survival and reproduction. Biogenic amines, such as like serotonin, are conserved neurotransmitters that regulate behavior and metabolism in relation to energy status. Disruptions of biogenic amine signaling contribute to human neurological diseases of mood, appetite, and movement. In this study, we investigated the roles of the biogenic amines serotonin and octopamine in regulating locomotion behaviors associated with feeding and fasting in the roundworm Caenorhabditis elegans We identified neural circuits through which these signals work to govern behavior. Understanding the molecular pathways through which biogenic amines function in model organisms may improve our understanding of dysfunctions of appetite and behavior found in mammals, including humans.
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Han Z, Boas S, Schroeder NE. Serotonin Regulates the Feeding and Reproductive Behaviors of Pratylenchus penetrans. PHYTOPATHOLOGY 2017; 107:872-877. [PMID: 28398877 PMCID: PMC6525625 DOI: 10.1094/phyto-11-16-0397-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The success of all plant-parasitic nematodes is dependent on the completion of several complex behaviors. The lesion nematode Pratylenchus penetrans is an economically important parasite of a diverse range of plant hosts. Unlike the cyst and root-knot nematodes, P. penetrans moves both within and outside of the host roots and can feed from both locations. Adult females of P. penetrans require insemination by actively moving males for reproduction and can lay eggs both within and outside of the host roots. We do not have a complete understanding of the molecular basis for these behaviors. One candidate modulator of these behaviors is the neurotransmitter serotonin. Previous research demonstrated an effect of exogenously applied serotonin on the feeding and male mating behaviors of cyst and root-knot nematodes. However, there are no data on the role of exogenous serotonin on lesion nematodes. Similarly, there are no data on the presence and function of endogenous serotonin in any plant-parasitic nematode. Here, we establish that exogenous serotonin applied to P. penetrans regulates both feeding and sex-specific behaviors. Furthermore, using immunohistochemistry and pharmacological assays, our data suggest that P. penetrans utilizes endogenous serotonin to regulate both feeding and sex-specific behaviors.
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Affiliation(s)
- Ziduan Han
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
| | - Stephanie Boas
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
| | - Nathan E Schroeder
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
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Cannabinoids Activate Monoaminergic Signaling to Modulate Key C. elegans Behaviors. J Neurosci 2017; 37:2859-2869. [PMID: 28188220 DOI: 10.1523/jneurosci.3151-16.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 01/22/2017] [Accepted: 02/01/2017] [Indexed: 12/22/2022] Open
Abstract
Cannabis sativa, or marijuana, a popular recreational drug, alters sensory perception and exerts a range of potential medicinal benefits. The present study demonstrates that the endogenous cannabinoid receptor agonists 2-arachidonoylglycerol (2-AG) and anandamide (AEA) activate a canonical cannabinoid receptor in Caenorhabditis elegans and also modulate monoaminergic signaling at multiple levels. 2-AG or AEA inhibit nociception and feeding through a pathway requiring the cannabinoid-like receptor NPR-19. 2-AG or AEA activate NPR-19 directly and cannabinoid-dependent inhibition can be rescued in npr-19-null animals by the expression of a human cannabinoid receptor, CB1, highlighting the orthology of the receptors. Cannabinoids also modulate nociception and locomotion through an NPR-19-independent pathway requiring an α2A-adrenergic-like octopamine (OA) receptor, OCTR-1, and a 5-HT1A-like serotonin (5-HT) receptor, SER-4, that involves a complex interaction among cannabinoid, octopaminergic, and serotonergic signaling. 2-AG activates OCTR-1 directly. In contrast, 2-AG does not activate SER-4 directly, but appears to enhance SER-4-dependent serotonergic signaling by increasing endogenous 5-HT. This study defines a conserved cannabinoid signaling system in C. elegans, demonstrates the cannabinoid-dependent activation of monoaminergic signaling, and highlights the advantages of studying cannabinoid signaling in a genetically tractable whole-animal model.SIGNIFICANCE STATEMENTCannabis sativa, or marijuana, causes euphoria and exerts a wide range of medicinal benefits. For years, cannabinoids have been studied at the cellular level using tissue explants with conflicting results. To better understand cannabinoid signaling, we have used the Caenorhabditis elegans model to examine the effects of cannabinoids on behavior. The present study demonstrates that mammalian cannabinoid receptor ligands activate a conserved cannabinoid signaling system in C. elegans and also modulate monoaminergic signaling, potentially affecting an array of disorders, including anxiety and depression. This study highlights the potential role of cannabinoids in modulating monoaminergic signaling and the advantages of studying cannabinoid signaling in a genetically tractable, whole-animal model.
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Lee KS, Iwanir S, Kopito RB, Scholz M, Calarco JA, Biron D, Levine E. Serotonin-dependent kinetics of feeding bursts underlie a graded response to food availability in C. elegans. Nat Commun 2017; 8:14221. [PMID: 28145493 PMCID: PMC5296638 DOI: 10.1038/ncomms14221] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 12/08/2016] [Indexed: 11/16/2022] Open
Abstract
Animals integrate physiological and environmental signals to modulate their food uptake. The nematode C. elegans, whose food uptake consists of pumping bacteria from the environment into the gut, provides excellent opportunities for discovering principles of conserved regulatory mechanisms. Here we show that worms implement a graded feeding response to the concentration of environmental bacteria by modulating a commitment to bursts of fast pumping. Using long-term, high-resolution, longitudinal recordings of feeding dynamics under defined conditions, we find that the frequency and duration of pumping bursts increase and the duration of long pauses diminishes in environments richer in bacteria. The bioamine serotonin is required for food-dependent induction of bursts as well as for maintaining their high rate of pumping through two distinct mechanisms. We identify the differential roles of distinct families of serotonin receptors in this process and propose that regulation of bursts is a conserved mechanism of behaviour and motor control.
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Affiliation(s)
- Kyung Suk Lee
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Shachar Iwanir
- Department of Physics and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Ronen B. Kopito
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Monika Scholz
- Department of Physics and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - John A. Calarco
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - David Biron
- Department of Physics and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
- The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Erel Levine
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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38
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Lemieux GA, Ashrafi K. Investigating Connections between Metabolism, Longevity, and Behavior in Caenorhabditis elegans. Trends Endocrinol Metab 2016; 27:586-596. [PMID: 27289335 PMCID: PMC4958586 DOI: 10.1016/j.tem.2016.05.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 01/19/2023]
Abstract
An overview of Caenorhabditis elegans as an experimental organism for studying energy balance is presented. Some of the unresolved questions that complicate the interpretation of lipid measurements from C. elegans are highlighted. We review studies that show that both lipid synthesis and lipid breakdown pathways are activated and needed for the longevity of hermaphrodites that lack their germlines. These findings illustrate the heterogeneity of triglyceride-rich lipid particles in C. elegans and reveal specific lipid signals that promote longevity. Finally, we provide a brief overview of feeding behavioral responses of C. elegans to varying nutritional conditions and highlight an unanticipated metabolic pathway that allows the incorporation of experience in feeding behavior.
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Affiliation(s)
| | - Kaveh Ashrafi
- University of California, San Francisco, San Francisco, CA, USA.
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39
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Scholz M, Lynch DJ, Lee KS, Levine E, Biron D. A scalable method for automatically measuring pharyngeal pumping in C. elegans. J Neurosci Methods 2016; 274:172-178. [PMID: 27474347 DOI: 10.1016/j.jneumeth.2016.07.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 07/21/2016] [Accepted: 07/22/2016] [Indexed: 11/20/2022]
Abstract
BACKGROUND The nematode Caenorhabditis elegans is widely used for studying small neural circuits underlying behavior. In particular, the rhythmic feeding motions collectively termed pharyngeal pumping are regulated by a nearly autonomous network of 20 neurons of 14 types. Despite much progress achieved through laser ablation, genetics, electrophysiology, and optogenetics, key questions regarding the regulation of pumping remain open. NEW METHOD We describe the implementation and application of a scalable automated method for measuring pumping in controlled environments. Our implementation is affordable and flexible: key hardware and software elements can be modified to accommodate different requirements. RESULTS We demonstrate prolonged measurements under controlled conditions and the resulting high quality data. We show the scalability of our method, enabling high throughput, and its suitability for maintaining static and dynamic conditions. When food availability was oscillated, pumping rates were low as compared to steady conditions and pumping activity was not reliably modulated in response to changes in food concentration. COMPARISON WITH EXISTING METHOD The prevailing method for measuring rates of pumping relies on scoring by visual inspection of short recordings. Our automated method compares well with manual scoring. It enables detailed statistical characterization under experimental conditions not previously accessible and minimizes unintentional bias. CONCLUSIONS Our approach adds a powerful tool for studying pharyngeal pumping. It enhances the experimental versatility of assaying genetic and pharmacological manipulations and the ability to characterize the resulting behavior. Both the experimental setup and the analysis can be readily adapted to additional challenging motion detection problems.
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Affiliation(s)
- Monika Scholz
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Dylan J Lynch
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Kyung Suk Lee
- Department of Physics and Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Erel Levine
- Department of Physics and Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - David Biron
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA; Department of Physics, The University of Chicago, Chicago, IL 60637, USA.
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40
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Serotonin promotes exploitation in complex environments by accelerating decision-making. BMC Biol 2016; 14:9. [PMID: 26847342 PMCID: PMC4743430 DOI: 10.1186/s12915-016-0232-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 01/21/2016] [Indexed: 01/22/2023] Open
Abstract
Background Fast responses can provide a competitive advantage when resources are inhomogeneously distributed. The nematode Caenorhabditis elegans was shown to modulate locomotion on a lawn of bacterial food in serotonin (5-HT)-dependent manners. However, potential roles for serotonergic signaling in responding to food discovery are poorly understood. Results We found that 5-HT signaling in C. elegans facilitates efficient exploitation in complex environments by mediating a rapid response upon encountering food. Genetic or cellular manipulations leading to deficient serotonergic signaling resulted in gradual responses and defective exploitation of a patchy foraging landscape. Physiological imaging revealed that the NSM serotonergic neurons responded acutely upon encounter with newly discovered food and were key to rapid responses. In contrast, the onset of responses of ADF serotonergic neurons preceded the physical encounter with the food. The serotonin-gated chloride channel MOD-1 and the ortholog of mammalian 5-HT1 metabotropic serotonin receptors SER-4 acted in synergy to accelerate decision-making. The relevance of responding rapidly was demonstrated in patchy environments, where the absence of 5-HT signaling was detrimental to exploitation. Conclusions Our results implicate 5-HT in a novel form of decision-making, demonstrate its fitness consequences, suggest that NSM and ADF act in concert to modulate locomotion in complex environments, and identify the synergistic action of a channel and a metabotropic receptor in accelerating C. elegans decision-making. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0232-y) contains supplementary material, which is available to authorized users.
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Park MR, Oh S, Son SJ, Park DJ, Oh S, Kim SH, Jeong DY, Oh NS, Lee Y, Song M, Kim Y. Bacillus licheniformis Isolated from Traditional Korean Food Resources Enhances the Longevity of Caenorhabditis elegans through Serotonin Signaling. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:10227-10233. [PMID: 26541069 DOI: 10.1021/acs.jafc.5b03730] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this study, we investigated potentially probiotic Bacillus licheniformis strains isolated from traditional Korean food sources for ability to enhance longevity using the nematode Caenorhabditis elegans as a simple in vivo animal model. We first investigated whether B. licheniformis strains were capable of modulating the lifespan of C. elegans. Among the tested strains, preconditioning with four B. licheniformis strains significantly enhanced the longevity of C. elegans. Unexpectedly, plate counting and transmission electron microscopy (TEM) results indicated that B. licheniformis strains were not more highly attached to the C. elegans intestine compared with Escherichia coli OP50 or Lactobacillus rhamnosus GG controls. In addition, qRT-PCR and an aging assay with mutant worms showed that the conditioning of B. licheniformis strain 141 directly influenced genes associated with serotonin signaling in nematodes, including tph-1 (tryptophan hydroxylase), bas-1 (serotonin- and dopamine-synthetic aromatic amino acid decarboxylase), mod-1 (serotonin-gated chloride channel), ser-1, and ser-7 (serotonin receptors) during C. elegans aging. Our findings suggest that B. licheniformis strain 141, which is isolated from traditional Korean foods, is a probiotic generally recognized as safe (GRAS) strain that enhances the lifespan of C. elegans via host serotonin signaling.
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Affiliation(s)
- Mi Ri Park
- BK21 Plus Graduate Program, Department of Animal Science and Institute Agricultural Science & Technology, Chonbuk National University , Jeonju 561-756, Korea
| | - Sangnam Oh
- BK21 Plus Graduate Program, Department of Animal Science and Institute Agricultural Science & Technology, Chonbuk National University , Jeonju 561-756, Korea
| | - Seok Jun Son
- BK21 Plus Graduate Program, Department of Animal Science and Institute Agricultural Science & Technology, Chonbuk National University , Jeonju 561-756, Korea
| | - Dong-June Park
- Korea Food Research Institute , Seongnam-si, Gyeonggi-do 463-746, Korea
| | - Sejong Oh
- Division of Animal Science, Chonnam National University , Gwangju 500-757, Korea
| | - Sae Hun Kim
- Division of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University , 136-701 Seoul, Korea
| | - Do-Youn Jeong
- Microbial Institute for Fermentation Industry , Sunchang, Jeonbuk 595-804, Republic of Korea
| | - Nam Su Oh
- R&D Center, Seoul Dairy Cooperative , Ansan, Gyeonggi-do 425-839, South Korea
| | - Youngbok Lee
- Department of Applied Chemistry, Hanyang University , ERICA Campus, Ansan, Gyeonggi-do 426-791, Korea
| | - Minho Song
- Department of Animal Science and Biotechnology, Chungnam National University , Daejeon 305-764, Korea
| | - Younghoon Kim
- BK21 Plus Graduate Program, Department of Animal Science and Institute Agricultural Science & Technology, Chonbuk National University , Jeonju 561-756, Korea
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Dallière N, Bhatla N, Luedtke Z, Ma DK, Woolman J, Walker RJ, Holden-Dye L, O'Connor V. Multiple excitatory and inhibitory neural signals converge to fine-tune Caenorhabditis elegans feeding to food availability. FASEB J 2015; 30:836-48. [PMID: 26514165 DOI: 10.1096/fj.15-279257] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/13/2015] [Indexed: 01/02/2023]
Abstract
How an animal matches feeding to food availability is a key question for energy homeostasis. We addressed this in the nematode Caenorhabditis elegans, which couples feeding to the presence of its food (bacteria) by regulating pharyngeal activity (pumping). We scored pumping in the presence of food and over an extended time course of food deprivation in wild-type and mutant worms to determine the neural substrates of adaptive behavior. Removal of food initially suppressed pumping but after 2 h this was accompanied by intermittent periods of high activity. We show pumping is fine-tuned by context-specific neural mechanisms and highlight a key role for inhibitory glutamatergic and excitatory cholinergic/peptidergic drives in the absence of food. Additionally, the synaptic protein UNC-31 [calcium-activated protein for secretion (CAPS)] acts through an inhibitory pathway not explained by previously identified contributions of UNC-31/CAPS to neuropeptide or glutamate transmission. Pumping was unaffected by laser ablation of connectivity between the pharyngeal and central nervous system indicating signals are either humoral or intrinsic to the enteric system. This framework in which control is mediated through finely tuned excitatory and inhibitory drives resonates with mammalian hypothalamic control of feeding and suggests that fundamental regulation of this basic animal behavior may be conserved through evolution from nematode to human.
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Affiliation(s)
- Nicolas Dallière
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Nikhil Bhatla
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Zara Luedtke
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Dengke K Ma
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jonathan Woolman
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Robert J Walker
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lindy Holden-Dye
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Vincent O'Connor
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Abstract
The compact nervous system of Caenorhabditis elegans and its genetic tractability are features that make this organism highly suitable for investigating energy balance in an animal system. Here, we focus on molecular components and organizational principles emerging from the investigation of pathways that largely originate in the nervous system and regulate feeding behavior but also peripheral fat regulation through neuroendocrine signaling. We provide an overview of studies aimed at understanding how C. elegans integrate internal and external cues in feeding behavior. We highlight some of the similarities and differences in energy balance between C. elegans and mammals. We also provide our perspective on unresolved issues, both conceptual and technical, that we believe have hampered critical evaluation of findings relevant to fat regulation in C. elegans.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California, San Francisco, California 94158;
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, California 94158;
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44
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Albin S, Kaun K, Knapp JM, Chung P, Heberlein U, Simpson J. A Subset of Serotonergic Neurons Evokes Hunger in Adult Drosophila. Curr Biol 2015; 25:2435-40. [DOI: 10.1016/j.cub.2015.08.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 07/01/2015] [Accepted: 08/04/2015] [Indexed: 01/18/2023]
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45
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Kniazeva M, Zhu H, Sewell AK, Han M. A Lipid-TORC1 Pathway Promotes Neuronal Development and Foraging Behavior under Both Fed and Fasted Conditions in C. elegans. Dev Cell 2015; 33:260-71. [PMID: 25892013 DOI: 10.1016/j.devcel.2015.02.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 12/17/2014] [Accepted: 02/18/2015] [Indexed: 01/12/2023]
Abstract
Food deprivation suppresses animal growth and development but spares the systems essential for foraging. The mechanisms underlying this selective development, and potential roles of lipids in it, are unclear. When C. elegans hatch in a food-free environment, postembryonic growth and development stall, but sensory neuron differentiation and neuronal development required for food responses continue. Here, we show that monomethyl branched-chain fatty acids (mmBCFAs) and their derivative, d17iso-glucosylceramide, function in the intestine to promote foraging behavior and sensory neuron maturation through both TORC1-dependent and -independent mechanisms. We show that mmBCFAs impact the expression of a subset of genes, including ceh-36/Hox, which we show to play a key role in mediating the regulation of the neuronal functions by this lipid pathway. This study uncovers that a lipid pathway promotes neuronal functions involved in foraging under both fed and fasting conditions and adds critical insight into the physiological functions of TORC1.
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Affiliation(s)
- Marina Kniazeva
- Howard Hughes Medical Institute; Department of Molecular Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA.
| | - Huanhu Zhu
- Howard Hughes Medical Institute; Department of Molecular Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Aileen K Sewell
- Howard Hughes Medical Institute; Department of Molecular Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Min Han
- Howard Hughes Medical Institute; Department of Molecular Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA.
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46
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Zhang L, Gualberto DG, Guo X, Correa P, Jee C, Garcia LR. TMC-1 attenuates C. elegans development and sexual behaviour in a chemically defined food environment. Nat Commun 2015; 6:6345. [PMID: 25695879 DOI: 10.1038/ncomms7345] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 01/21/2015] [Indexed: 01/22/2023] Open
Abstract
Although diet affects growth and behaviour, the adaptive mechanisms that coordinate these processes in non-optimal food sources are unclear. Here we show that the C. elegans tmc-1 channel, which is homologous to the mammalian tmc deafness genes, attenuates development and inhibits sexual behaviour in non-optimal food, the synthetic CeMM medium. In CeMM medium, signalling from the pharyngeal MC neurons and body wall muscles slows larval development. However, in the non-standard diet, mutation in tmc-1 accelerates development, by impairing the excitability of these cells. The tmc-1 larva can immediately generate ATP when fed CeMM, and their fast development requires insulin signalling. Our findings suggest that the tmc-1 channel indirectly affects metabolism in wild-type animals. In addition to regulating the development, we show that mutating tmc-1 can relax diet-induced inhibition of male sexual behaviour, thus indicating that a single regulator can be genetically modified to promote growth rate and reproductive success in new environments.
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Affiliation(s)
- Liusuo Zhang
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Daisy G Gualberto
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Xiaoyan Guo
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Paola Correa
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Changhoon Jee
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - L Rene Garcia
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
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47
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Lemieux GA, Cunningham KA, Lin L, Mayer F, Werb Z, Ashrafi K. Kynurenic acid is a nutritional cue that enables behavioral plasticity. Cell 2015; 160:119-31. [PMID: 25594177 PMCID: PMC4334586 DOI: 10.1016/j.cell.2014.12.028] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/16/2014] [Accepted: 12/11/2014] [Indexed: 12/27/2022]
Abstract
The kynurenine pathway of tryptophan metabolism is involved in the pathogenesis of several brain diseases, but its physiological functions remain unclear. We report that kynurenic acid, a metabolite in this pathway, functions as a regulator of food-dependent behavioral plasticity in C. elegans. The experience of fasting in C. elegans alters a variety of behaviors, including feeding rate, when food is encountered post-fast. Levels of neurally produced kynurenic acid are depleted by fasting, leading to activation of NMDA-receptor-expressing interneurons and initiation of a neuropeptide-y-like signaling axis that promotes elevated feeding through enhanced serotonin release when animals re-encounter food. Upon refeeding, kynurenic acid levels are eventually replenished, ending the elevated feeding period. Because tryptophan is an essential amino acid, these findings suggest that a physiological role of kynurenic acid is in directly linking metabolism to activity of NMDA and serotonergic circuits, which regulate a broad range of behaviors and physiologies.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Katherine A Cunningham
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Lin Lin
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Fahima Mayer
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Zena Werb
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94143-0452, USA
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA.
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48
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Neuronal serotonin release triggers the heat shock response in C. elegans in the absence of temperature increase. Curr Biol 2014; 25:163-174. [PMID: 25557666 DOI: 10.1016/j.cub.2014.11.040] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/13/2014] [Accepted: 11/17/2014] [Indexed: 01/07/2023]
Abstract
BACKGROUND Cellular mechanisms aimed at repairing protein damage and maintaining homeostasis, widely understood to be triggered by the damage itself, have recently been shown to be under cell nonautonomous control in the metazoan C. elegans. The heat shock response (HSR) is one such conserved mechanism, activated by cells upon exposure to proteotoxic conditions such as heat. Previously, we had shown that this conserved cytoprotective response is regulated by the thermosensory neuronal circuitry of C. elegans. Here, we investigate the mechanisms and physiological relevance of neuronal control. RESULTS By combining optogenetic methods with live visualization of the dynamics of the heat shock transcription factor (HSF1), we show that excitation of the AFD thermosensory neurons is sufficient to activate HSF1 in another cell, even in the absence of temperature increase. Excitation of the AFD thermosensory neurons enhances serotonin release. Serotonin release elicited by direct optogenetic stimulation of serotonergic neurons activates HSF1 and upregulates molecular chaperones through the metabotropic serotonin receptor SER-1. Consequently, excitation of serotonergic neurons alone can suppress protein misfolding in C. elegans peripheral tissue. CONCLUSIONS These studies imply that thermosensory activity coupled to serotonergic signaling is sufficient to activate the protective HSR prior to frank proteotoxic damage. The ability of neurosensory release of serotonin to control cellular stress responses and activate HSF1 has powerful implications for the treatment of protein conformation diseases.
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49
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Komuniecki R, Hapiak V, Harris G, Bamber B. Context-dependent modulation reconfigures interactive sensory-mediated microcircuits in Caenorhabditis elegans. Curr Opin Neurobiol 2014; 29:17-24. [DOI: 10.1016/j.conb.2014.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 01/04/2023]
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50
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Trojanowski NF, Padovan-Merhar O, Raizen DM, Fang-Yen C. Neural and genetic degeneracy underlies Caenorhabditis elegans feeding behavior. J Neurophysiol 2014; 112:951-61. [PMID: 24872529 DOI: 10.1152/jn.00150.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Degenerate networks, in which structurally distinct elements can perform the same function or yield the same output, are ubiquitous in biology. Degeneracy contributes to the robustness and adaptability of networks in varied environmental and evolutionary contexts. However, how degenerate neural networks regulate behavior in vivo is poorly understood, especially at the genetic level. Here, we identify degenerate neural and genetic mechanisms that underlie excitation of the pharynx (feeding organ) in the nematode Caenorhabditis elegans using cell-specific optogenetic excitation and inhibition. We show that the pharyngeal neurons MC, M2, M4, and I1 form multiple direct and indirect excitatory pathways in a robust network for control of pharyngeal pumping. I1 excites pumping via MC and M2 in a state-dependent manner. We identify nicotinic and muscarinic receptors through which the pharyngeal network regulates feeding rate. These results identify two different mechanisms by which degeneracy is manifest in a neural circuit in vivo.
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Affiliation(s)
- Nicholas F Trojanowski
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Olivia Padovan-Merhar
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David M Raizen
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Christopher Fang-Yen
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul, South Korea
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