1
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Kramer TS, Wan FK, Pugliese SM, Atanas AA, Hiser AW, Luo J, Bueno E, Flavell SW. Neural Sequences Underlying Directed Turning in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.11.607076. [PMID: 39149398 PMCID: PMC11326294 DOI: 10.1101/2024.08.11.607076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Complex behaviors like navigation rely on sequenced motor outputs that combine to generate effective movement. The brain-wide organization of the circuits that integrate sensory signals to select and execute appropriate motor sequences is not well understood. Here, we characterize the architecture of neural circuits that control C. elegans olfactory navigation. We identify error-correcting turns during navigation and use whole-brain calcium imaging and cell-specific perturbations to determine their neural underpinnings. These turns occur as motor sequences accompanied by neural sequences, in which defined neurons activate in a stereotyped order during each turn. Distinct neurons in this sequence respond to sensory cues, anticipate upcoming turn directions, and drive movement, linking key features of this sensorimotor behavior across time. The neuromodulator tyramine coordinates these sequential brain dynamics. Our results illustrate how neuromodulation can act on a defined neural architecture to generate sequential patterns of activity that link sensory cues to motor actions.
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Affiliation(s)
- Talya S. Kramer
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
- MIT Biology Graduate Program, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Flossie K. Wan
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sarah M. Pugliese
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Adam A. Atanas
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alex W. Hiser
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jinyue Luo
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eric Bueno
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Steven W. Flavell
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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2
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Sharma AK, Randi F, Kumar S, Dvali S, Leifer AM. TWISP: a transgenic worm for interrogating signal propagation in Caenorhabditis elegans. Genetics 2024; 227:iyae077. [PMID: 38733622 PMCID: PMC11228852 DOI: 10.1093/genetics/iyae077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 02/11/2024] [Accepted: 04/11/2024] [Indexed: 05/13/2024] Open
Abstract
Genetically encoded optical indicators and actuators of neural activity allow for all-optical investigations of signaling in the nervous system. But commonly used indicators, actuators, and expression strategies are poorly suited for systematic measurements of signal propagation at brain scale and cellular resolution. Large-scale measurements of the brain require indicators and actuators with compatible excitation spectra to avoid optical crosstalk. They must be highly expressed in every neuron but at the same time avoid lethality and permit the animal to reach adulthood. Their expression must also be compatible with additional fluorescent labels to locate and identify neurons, such as those in the NeuroPAL cell identification system. We present TWISP, a transgenic worm for interrogating signal propagation, that addresses these needs and enables optical measurements of evoked calcium activity at brain scale and cellular resolution in the nervous system of the nematode Caenorhabditis elegans. In every neuron we express a nonconventional optical actuator, the gustatory receptor homolog GUR-3 + PRDX-2, under the control of a drug-inducible system QF + hGR, and a calcium indicator GCAMP6s, in a background with additional fluorophores from the NeuroPAL cell ID system. We show that this combination, but not others tested, avoids optical crosstalk, creates strong expression in the adult, and generates stable transgenic lines for systematic measurements of signal propagation in the worm brain.
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Affiliation(s)
- Anuj Kumar Sharma
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Francesco Randi
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Sandeep Kumar
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
| | - Sophie Dvali
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Andrew M Leifer
- Department of Physics, Princeton University, Princeton, NJ 08544, USA
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
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3
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Bechtel W, Bich L. Using neurons to maintain autonomy: Learning from C. elegans. Biosystems 2023; 232:105017. [PMID: 37666409 DOI: 10.1016/j.biosystems.2023.105017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/06/2023]
Abstract
Understanding how biological organisms are autonomous-maintain themselves far from equilibrium through their own activities-requires understanding how they regulate those activities. In multicellular animals, such control can be exercised either via endocrine signaling through the vasculature or via neurons. In C. elegans this control is exercised by a well-delineated relatively small but distributed nervous system that relies on both chemical and electric transmission of signals. This system provides resources to integrate information from multiple sources as needed to maintain the organism. Especially important for the exercise of neural control are neuromodulators, which we present as setting agendas for control through more traditional electrical signaling. To illustrate how the C. elegans nervous system integrates multiple sources of information in controlling activities important for autonomy, we focus on feeding behavior and responses to adverse conditions. We conclude by considering how a distributed nervous system without a centralized controller is nonetheless adequate for autonomy.
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Affiliation(s)
- William Bechtel
- Department of Philosophy; University of California, San Diego; La Jolla, CA 92093-0119, USA.
| | - Leonardo Bich
- IAS-Research Centre for Life, Mind and Society; Department of Philosophy; University of the Basque Country (UPV/EHU); Avenida de Tolosa 70; Donostia-San Sebastian, 20018; Spain.
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4
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Cannon KE, Ranasinghe M, Millhouse PW, Roychowdhury A, Dobrunz LE, Foulger SH, Gauntt DM, Anker JN, Bolding M. LITE-1 mediates behavioral responses to X-rays in Caenorhabditis elegans. Front Neurosci 2023; 17:1210138. [PMID: 37638310 PMCID: PMC10450342 DOI: 10.3389/fnins.2023.1210138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/26/2023] [Indexed: 08/29/2023] Open
Abstract
Rapid sensory detection of X-ray stimulation has been documented across a wide variety of species, but few studies have explored the underlying molecular mechanisms. Here we report the discovery of an acute behavioral avoidance response in wild type Caenorhabditis elegans to X-ray stimulation. The endogenous C. elegans UV-photoreceptor protein LITE-1 was found to mediate the locomotory avoidance response. Transgenic expression of LITE-1 in C. elegans muscle cells resulted in paralysis and egg ejection responses to X-ray stimulation, demonstrating that ectopic expression of LITE-1 can confer X-ray sensitivity to otherwise X-ray insensitive cells. This work represents the first demonstration of rapid X-ray based genetically targeted (X-genetic) manipulation of cellular electrical activity in intact behaving animals. Our findings suggest that LITE-1 has strong potential for use in this minimally invasive form of neuromodulation to transduce transcranial X-ray signals for precise manipulation of neural activity in mammals, bypassing the need for invasive surgical implants to deliver stimulation.
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Affiliation(s)
- Kelli E. Cannon
- Department of Vision Sciences, School of Optometry, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Neurobiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Radiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | | | - Paul W. Millhouse
- Department of Chemistry, Clemson University, Clemson, SC, United States
| | - Ayona Roychowdhury
- Department of Radiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Lynn E. Dobrunz
- Department of Neurobiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Stephen H. Foulger
- Department of Materials Science and Engineering, College of Engineering, Computing and Applied Sciences, Clemson University, Clemson, SC, United States
| | - David M. Gauntt
- Department of Radiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jeffrey N. Anker
- Department of Chemistry, Clemson University, Clemson, SC, United States
| | - Mark Bolding
- Department of Radiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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5
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Sharma AK, Randi F, Kumar S, Dvali S, Leifer AM. TWISP: A Transgenic Worm for Interrogating Signal Propagation in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.03.551820. [PMID: 37577580 PMCID: PMC10418184 DOI: 10.1101/2023.08.03.551820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Genetically encoded optical indicators and actuators of neural activity allow for all-optical investigations of signaling in the nervous system. But commonly used indicators, actuators and expression strategies are poorly suited for systematic measurements of signal propagation at brain scale and cellular resolution. Large scale measurements of the brain require indicators and actuators with compatible excitation spectra to avoid optical crosstalk. They must be highly expressed in every neuron but at the same time avoid lethality and permit the animal to reach adulthood. And finally, their expression must be compatible with additional fluorescent labels to locate and identify neurons, such as those in the NeuroPAL cell identification system. We present TWISP, a Transgenic Worm for Interrogating Signal Propagation, that address these needs and enables optical measurements of evoked calcium activity at brain scale and cellular resolution in the nervous system of the nematode Caenorhabditis elegans. We express in every neuron a non-conventional optical actuator, the gustatory receptor homolog GUR-3+PRDX-2 under the control of a drug-inducible system QF+hGR, and calcium indicator GCAMP6s, in a background with additional fluorophores of the NeuroPAL cell ID system. We show that this combination, but not others tested, avoids optical-crosstalk, creates strong expression in the adult, and generates stable transgenic lines for systematic measurements of signal propagation in the worm brain.
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Affiliation(s)
| | - Francesco Randi
- Department of Physics, Princeton University, Princeton, NJ, 08544
| | - Sandeep Kumar
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, 08544
| | - Sophie Dvali
- Department of Physics, Princeton University, Princeton, NJ, 08544
| | - Andrew M Leifer
- Department of Physics, Princeton University, Princeton, NJ, 08544
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, 08544
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6
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Han S, Sims A, Aceto A, Schmidt BF, Bruchez MP, Gurkar AU. A Chemoptogenetic Tool for Spatiotemporal Induction of Oxidative DNA Lesions In Vivo. Genes (Basel) 2023; 14:485. [PMID: 36833412 PMCID: PMC9956269 DOI: 10.3390/genes14020485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/17/2023] Open
Abstract
Oxidative nuclear DNA damage increases in all tissues with age in multiple animal models, as well as in humans. However, the increase in DNA oxidation varies from tissue to tissue, suggesting that certain cells/tissues may be more vulnerable to DNA damage than others. The lack of a tool that can control dosage and spatiotemporal induction of oxidative DNA damage, which accumulates with age, has severely limited our ability to understand how DNA damage drives aging and age-related diseases. To overcome this, here we developed a chemoptogenetic tool that produces 8-oxoguanine (8-oxoG) at DNA in a whole organism, Caenorhabditis elegans. This tool uses di-iodinated malachite green (MG-2I) photosensitizer dye that generates singlet oxygen, 1O2, upon fluorogen activating peptide (FAP) binding and excitation with far-red light. Using our chemoptogenetic tool, we are able to control generation of singlet oxygen ubiquitously or in a tissue-specific manner, including in neurons and muscle cells. To induce oxidative DNA damage, we targeted our chemoptogenetic tool to histone, his-72, that is expressed in all cell types. Our results show that a single exposure to dye and light is able to induce DNA damage, promote embryonic lethality, lead to developmental delay, and significantly reduce lifespan. Our chemoptogenetic tool will now allow us to assess the cell autonomous versus non-cell autonomous role of DNA damage in aging, at an organismal level.
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Affiliation(s)
- Suhao Han
- Aging Institute of UPMC, The University of Pittsburgh School of Medicine, 100 Technology Dr, Pittsburgh, PA 15219, USA
| | - Austin Sims
- Aging Institute of UPMC, The University of Pittsburgh School of Medicine, 100 Technology Dr, Pittsburgh, PA 15219, USA
| | - Anthony Aceto
- Aging Institute of UPMC, The University of Pittsburgh School of Medicine, 100 Technology Dr, Pittsburgh, PA 15219, USA
| | - Brigitte F. Schmidt
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Marcel P. Bruchez
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
| | - Aditi U. Gurkar
- Aging Institute of UPMC, The University of Pittsburgh School of Medicine, 100 Technology Dr, Pittsburgh, PA 15219, USA
- Division of Geriatric Medicine, Department of Medicine, University of Pittsburgh School of Medicine, 3471 Fifth Avenue, Kaufmann Medical Building Suite 500, Pittsburgh, PA 15213, USA
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7
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Quintin S, Aspert T, Ye T, Charvin G. Distinct mechanisms underlie H2O2 sensing in C. elegans head and tail. PLoS One 2022; 17:e0274226. [PMID: 36173997 PMCID: PMC9521893 DOI: 10.1371/journal.pone.0274226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 08/23/2022] [Indexed: 12/29/2022] Open
Abstract
Environmental oxidative stress threatens cellular integrity and should therefore be avoided by living organisms. Yet, relatively little is known about environmental oxidative stress perception. Here, using microfluidics, we showed that like I2 pharyngeal neurons, the tail phasmid PHA neurons function as oxidative stress sensing neurons in C. elegans, but display different responses to H2O2 and light. We uncovered that different but related receptors, GUR-3 and LITE-1, mediate H2O2 signaling in I2 and PHA neurons. Still, the peroxiredoxin PRDX-2 is essential for both, and might promote H2O2-mediated receptor activation. Our work demonstrates that C. elegans can sense a broad range of oxidative stressors using partially distinct H2O2 signaling pathways in head and tail sensillae, and paves the way for further understanding of how the integration of these inputs translates into the appropriate behavior.
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Affiliation(s)
- Sophie Quintin
- Department of Developmental Biology and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Théo Aspert
- Department of Developmental Biology and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Tao Ye
- Department of Developmental Biology and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Gilles Charvin
- Department of Developmental Biology and Stem Cells, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France
- Université de Strasbourg, Illkirch, France
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8
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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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9
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Brenner IR, Raizen DM, Fang-Yen C. Pharyngeal timing and particle transport defects in Caenorhabditis elegans feeding mutants. J Neurophysiol 2022; 128:302-309. [PMID: 35730757 DOI: 10.1152/jn.00444.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The nematode C. elegans uses rhythmic muscle contractions (pumps) of the pharynx, a tubular feeding organ, to filter, transport, and crush food particles. A number of feeding mutants have been identified, including those with slow pharyngeal pumping rate, weak muscle contraction, defective muscle relaxation, and defective grinding of bacteria. Many aspects of these pharyngeal behavioral defects and how they affect pharyngeal function are not well understood. For example, the behavioral deficits underlying inefficient particle transport in 'slippery' mutants have been unclear. Here we use high speed video microscopy to describe pharyngeal pumping behaviors and particle transport in wild-type animals and in feeding mutants. Different 'slippery' mutants exhibit distinct defects including weak isthmus contraction, failure to trap particles in the anterior isthmus, and abnormal timing of contraction and relaxation in pharyngeal compartments. Our results show that multiple deficits in pharyngeal timing or contraction can cause defects in particle transport.
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Affiliation(s)
- Isaac Ravi Brenner
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia PA, United States
| | - David M Raizen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Christopher Fang-Yen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.,Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, United States
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10
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Hendricks M. C. elegans does a spit take. eLife 2021; 10:71813. [PMID: 34342265 PMCID: PMC8331175 DOI: 10.7554/elife.71813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 07/30/2021] [Indexed: 11/13/2022] Open
Abstract
Eating can turn into spitting because individual parts of a muscle cell are able to contract in different ways.
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11
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Sando SR, Bhatla N, Lee EL, Horvitz HR. An hourglass circuit motif transforms a motor program via subcellularly localized muscle calcium signaling and contraction. eLife 2021; 10:59341. [PMID: 34212858 PMCID: PMC8331187 DOI: 10.7554/elife.59341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/26/2021] [Indexed: 12/27/2022] Open
Abstract
Neural control of muscle function is fundamental to animal behavior. Many muscles can generate multiple distinct behaviors. Nonetheless, individual muscle cells are generally regarded as the smallest units of motor control. We report that muscle cells can alter behavior by contracting subcellularly. We previously discovered that noxious tastes reverse the net flow of particles through the C. elegans pharynx, a neuromuscular pump, resulting in spitting. We now show that spitting results from the subcellular contraction of the anterior region of the pm3 muscle cell. Subcellularly localized calcium increases accompany this contraction. Spitting is controlled by an ‘hourglass’ circuit motif: parallel neural pathways converge onto a single motor neuron that differentially controls multiple muscles and the critical subcellular muscle compartment. We conclude that subcellular muscle units enable modulatory motor control and propose that subcellular muscle contraction is a fundamental mechanism by which neurons can reshape behavior.
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Affiliation(s)
- Steven R Sando
- Howard Hughes Medical Institute, Department of Biology, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Nikhil Bhatla
- Howard Hughes Medical Institute, Department of Biology, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, United States.,Miller Institute, Helen Wills Neuroscience Institute, Department of Molecular and Cellular Biology, University of California, Berkeley, Berkeley, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Eugene Lq Lee
- Howard Hughes Medical Institute, Department of Biology, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - H Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, United States
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12
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Ghosh DD, Lee D, Jin X, Horvitz HR, Nitabach MN. C. elegans discriminates colors to guide foraging. Science 2021; 371:1059-1063. [PMID: 33674494 PMCID: PMC8554940 DOI: 10.1126/science.abd3010] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 01/08/2021] [Indexed: 12/14/2022]
Abstract
Color detection is used by animals of diverse phyla to navigate colorful natural environments and is thought to require evolutionarily conserved opsin photoreceptor genes. We report that Caenorhabditis elegans roundworms can discriminate between colors despite the fact that they lack eyes and opsins. Specifically, we found that white light guides C. elegans foraging decisions away from a blue-pigment toxin secreted by harmful bacteria. These foraging decisions are guided by specific blue-to-amber ratios of light. The color specificity of color-dependent foraging varies notably among wild C. elegans strains, which indicates that color discrimination is ecologically important. We identified two evolutionarily conserved cellular stress response genes required for opsin-independent, color-dependent foraging by C. elegans, and we speculate that cellular stress response pathways can mediate spectral discrimination by photosensitive cells and organisms-even by those lacking opsins.
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Affiliation(s)
- D Dipon Ghosh
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA.
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Dongyeop Lee
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Xin Jin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
| | - H Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael N Nitabach
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA.
- Department of Genetics, Yale University, New Haven, CT, USA
- Department of Neuroscience, Yale University, New Haven, CT, USA
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13
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Ishita Y, Chihara T, Okumura M. Different combinations of serotonin receptors regulate predatory and bacterial feeding behaviors in the nematode Pristionchus pacificus. G3-GENES GENOMES GENETICS 2021; 11:6104620. [PMID: 33598706 PMCID: PMC8022940 DOI: 10.1093/g3journal/jkab011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 12/28/2020] [Indexed: 11/23/2022]
Abstract
Feeding behavior is one of the most fundamental behaviors in animals, and regulation of this behavior is critical for proper food intake. The nematode Pristionchus pacificus exhibits dimorphism in feeding behavior, bacterial feeding and predatory feeding on other nematodes, and the latter behavior is assumed to be an evolutionarily novel behavior. Both types of feeding behavior are modulated by serotonin; however, the downstream mechanism that modulates these behaviors is still to be clarified. Here, we focused on serotonin receptors and examined their expression patterns in P. pacificus. We also generated knockout mutants of the serotonin receptors using the CRISPR/Cas9 system and examined feeding behaviors. We found that Ppa-ser-5 mutants and the Ppa-ser-1; Ppa-ser-7 double mutant decreased predation. Detailed observation of the pharyngeal movement revealed that the Ppa-ser-1; Ppa-ser-7 double mutant reduces tooth movement, which is required for efficient predatory feeding. Conversely, Ppa-ser-7 and Ppa-mod-1 mutants decreased bacterial feeding. This study revealed that specific combinations of serotonin receptors are essential for the modulation of these distinct feeding behaviors, providing insight into the evolution of neural pathways to regulate novel feeding behavior.
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Affiliation(s)
- Yuuki Ishita
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Takahiro Chihara
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.,Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Misako Okumura
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.,Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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14
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Abstract
The nematode worm Caenorhabditis elegans is a model for deciphering the neural circuitry that transmits information from sensory organ to muscle tissue. It is also studied for disentangling the characteristics of the network, the efficiency of its design, and for testing theoretical models on how information is encoded. For this study, the efficiency of the synaptic connections was studied by testing the robustness of the neural network. A randomization test of robustness was applied to previously computed neural modules of the pharynx of C. elegans. The results support robustness as a reason for the observed over connectiveness across the pharyngeal system. In addition, rare events of single-neuron loss may expectedly lead to loss of function in a neural system.
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Affiliation(s)
- Robert Friedman
- Department of Biological Sciences, University of South Carolina, Columbia, USA
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15
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Cook SJ, Crouse CM, Yemini E, Hall DH, Emmons SW, Hobert O. The connectome of the Caenorhabditis elegans pharynx. J Comp Neurol 2020; 528:2767-2784. [PMID: 32352566 PMCID: PMC7601127 DOI: 10.1002/cne.24932] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/06/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022]
Abstract
Detailed anatomical maps of individual organs and entire animals have served as invaluable entry points for ensuing dissection of their evolution, development, and function. The pharynx of the nematode Caenorhabditis elegans is a simple neuromuscular organ with a self-contained, autonomously acting nervous system, composed of 20 neurons that fall into 14 anatomically distinct types. Using serial electron micrograph (EM) reconstruction, we re-evaluate here the connectome of the pharyngeal nervous system, providing a novel and more detailed view of its structure and predicted function. Contrasting the previous classification of pharyngeal neurons into distinct inter- and motor neuron classes, we provide evidence that most pharyngeal neurons are also likely sensory neurons and most, if not all, pharyngeal neurons also classify as motor neurons. Together with the extensive cross-connectivity among pharyngeal neurons, which is more widespread than previously realized, the sensory-motor characteristics of most neurons define a shallow network architecture of the pharyngeal connectome. Network analysis reveals that the patterns of neuronal connections are organized into putative computational modules that reflect the known functional domains of the pharynx. Compared with the somatic nervous system, pharyngeal neurons both physically associate with a larger fraction of their neighbors and create synapses with a greater proportion of their neighbors. We speculate that the overall architecture of the pharyngeal nervous system may be reminiscent of the architecture of ancestral, primitive nervous systems.
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Affiliation(s)
- Steven J. Cook
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
| | - Charles M. Crouse
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Eviatar Yemini
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
| | - David H. Hall
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Scott W. Emmons
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Oliver Hobert
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
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16
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Burkhart KB, Sando SR, Corrionero A, Horvitz HR. H3.3 Nucleosome Assembly Mutants Display a Late-Onset Maternal Effect. Curr Biol 2020; 30:2343-2352.e3. [PMID: 32470364 DOI: 10.1016/j.cub.2020.04.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/31/2020] [Accepted: 04/20/2020] [Indexed: 01/03/2023]
Abstract
Maternally inherited RNA and proteins control much of embryonic development. The effect of such maternal information beyond embryonic development is largely unclear. Here, we report that maternal contribution of histone H3.3 assembly complexes can prevent the expression of late-onset anatomical, physiologic, and behavioral abnormalities of C. elegans. We show that mutants lacking hira-1, an evolutionarily conserved H3.3-deposition factor, have severe pleiotropic defects that manifest predominantly at adulthood. These late-onset defects can be maternally rescued, and maternally derived HIRA-1 protein can be detected in hira-1(-/-) progeny. Mitochondrial stress likely contributes to the late-onset defects, given that hira-1 mutants display mitochondrial stress, and the induction of mitochondrial stress results in at least some of the hira-1 late-onset abnormalities. A screen for mutants that mimic the hira-1 mutant phenotype identified PQN-80-a HIRA complex component, known as UBN1 in humans-and XNP-1-a second H3.3 chaperone, known as ATRX in humans. pqn-80 and xnp-1 abnormalities are also maternally rescued. Furthermore, mutants lacking histone H3.3 have a late-onset defect similar to a defect of hira-1, pqn-80, and xnp-1 mutants. These data demonstrate that H3.3 assembly complexes provide non-DNA-based heritable information that can markedly influence adult phenotype. We speculate that similar maternal effects might explain the missing heritability of late-onset human diseases, such as Alzheimer's disease, Parkinson's disease, and type 2 diabetes.
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Affiliation(s)
- Kirk B Burkhart
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Steven R Sando
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Anna Corrionero
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - H Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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17
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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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18
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Yañez-Guerra LA, Elphick MR. Evolution and Comparative Physiology of Luqin-Type Neuropeptide Signaling. Front Neurosci 2020; 14:130. [PMID: 32132900 PMCID: PMC7041311 DOI: 10.3389/fnins.2020.00130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/31/2020] [Indexed: 02/01/2023] Open
Abstract
Luqin is a neuropeptide that was discovered and named on account of its expression in left upper quadrant cells of the abdominal ganglion in the mollusc Aplysia californica. Subsequently, luqin-type peptides were identified as cardio-excitatory neuropeptides in other molluscs and a cognate receptor was discovered in the pond snail Lymnaea stagnalis. Phylogenetic analyses have revealed that orthologs of molluscan luqin-type neuropeptides occur in other phyla; these include neuropeptides in ecdysozoans (arthropods, nematodes) that have a C-terminal RYamide motif (RYamides) and neuropeptides in ambulacrarians (echinoderms, hemichordates) that have a C-terminal RWamide motif (RWamides). Furthermore, precursors of luqin-type neuropeptides typically have a conserved C-terminal motif containing two cysteine residues, although the functional significance of this is unknown. Consistent with the orthology of the neuropeptides and their precursors, phylogenetic and pharmacological studies have revealed that orthologous G-protein coupled receptors (GPCRs) mediate effects of luqin-type neuropeptides in spiralians, ecdysozoans, and ambulacrarians. Luqin-type signaling originated in a common ancestor of the Bilateria as a paralog of tachykinin-type signaling but, unlike tachykinin-type signaling, luqin-type signaling was lost in chordates. This may largely explain why luqin-type signaling has received less attention than many other neuropeptide signaling systems. However, insights into the physiological actions of luqin-type neuropeptides (RYamides) in ecdysozoans have been reported recently, with roles in regulation of feeding and diuresis revealed in insects and roles in regulation of feeding, egg laying, locomotion, and lifespan revealed in the nematode Caenorhabditis elegans. Furthermore, characterization of a luqin-type neuropeptide in the starfish Asterias rubens (phylum Echinodermata) has provided the first insights into the physiological roles of luqin-type signaling in a deuterostome. In conclusion, although luqin was discovered in Aplysia over 30 years ago, there is still much to be learnt about luqin-type neuropeptide signaling. This will be facilitated in the post-genomic era by the emerging opportunities for experimental studies on a variety of invertebrate taxa.
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Affiliation(s)
- Luis Alfonso Yañez-Guerra
- School of Biological and Chemical Sciences, Faculty of Science and Engineering, Queen Mary University of London, London, United Kingdom
| | - Maurice R Elphick
- School of Biological and Chemical Sciences, Faculty of Science and Engineering, Queen Mary University of London, London, United Kingdom
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19
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Ding SS, Romenskyy M, Sarkisyan KS, Brown AEX. Measuring Caenorhabditis elegans Spatial Foraging and Food Intake Using Bioluminescent Bacteria. Genetics 2020; 214:577-587. [PMID: 31911453 PMCID: PMC7054024 DOI: 10.1534/genetics.119.302804] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/06/2020] [Indexed: 01/08/2023] Open
Abstract
For most animals, feeding includes two behaviors: foraging to find a food patch and food intake once a patch is found. The nematode Caenorhabditis elegans is a useful model for studying the genetics of both behaviors. However, most methods of measuring feeding in worms quantify either foraging behavior or food intake, but not both. Imaging the depletion of fluorescently labeled bacteria provides information on both the distribution and amount of consumption, but even after patch exhaustion a prominent background signal remains, which complicates quantification. Here, we used a bioluminescent Escherichia coli strain to quantify C. elegans feeding. With light emission tightly coupled to active metabolism, only living bacteria are capable of bioluminescence, so the signal is lost upon ingestion. We quantified the loss of bioluminescence using N2 reference worms and eat-2 mutants, and found a nearly 100-fold increase in signal-to-background ratio and lower background compared to loss of fluorescence. We also quantified feeding using aggregating npr-1 mutant worms. We found that groups of npr-1 mutants first clear bacteria from within the cluster before foraging collectively for more food; similarly, during large population swarming, only worms at the migrating front are in contact with bacteria. These results demonstrate the usefulness of bioluminescent bacteria for quantifying feeding and generating insights into the spatial pattern of food consumption.
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Affiliation(s)
- Siyu Serena Ding
- Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
- Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
| | - Maksym Romenskyy
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Karen S Sarkisyan
- Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
- Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
| | - Andre E X Brown
- Institute of Clinical Sciences, Imperial College London, London W12 0NN, United Kingdom
- Medical Research Council London Institute of Medical Sciences, London W12 0NN, United Kingdom
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20
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Munro CJ, Nguyen MA, Falgons C, Chaudhry S, Olagunjo M, Bode A, Bobé C, Portela ME, Knecht MR, Collins KM. Identification of Toxicity Effects of Cu 2O Materials on C. elegans as a Function of Environmental Ionic Composition. ENVIRONMENTAL SCIENCE. NANO 2020; 7:645-655. [PMID: 32123564 PMCID: PMC7051015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Previous work has shown that spherical CuO nanomaterials show negative effects on cell and animal physiology. The biological effects of Cu2O materials, which posess unique chemical features compared to CuO nanomaterials and can be synthesized in a similarly large variety of shapes and sizes, are comparatively less studied. Here, we synthesized truncated octahedral Cu2O particles and characterized their structure, stability, and physiological effects in the nematode worm animal model, Caenorhabditis elegans. Cu2O particles were found to be generally stable in aqueous media, although the particles did show signs of oxidation and leaching of Cu2+ within hours in worm growth media. The particles were found to be especially sensitive to inorganic phosphate (PO4 3-) found in standard NGM nematode growth medium. Cu2O particles were observed being taken up into the nematode pharynx and detected in the lumen of the gut. Toxicity experiments revealed that treatment with Cu2O particles caused a significant reduction in animal size and lifespan. These toxic effects resembled treatment with Cu2+, but measurements of Cu leaching, worm size, and long-term behavior experiments show the particles are more toxic than expected from Cu ion leaching alone. These results suggest worm ingestion of intact Cu2O particles enhances their toxicity and behavior effects while particle exposure to environmental phosphate precipitates leached Cu2+ into biounavailable phosphate salts. Interestingly, the worms showed an acute avoidance of bacterial food with Cu2O particles, suggesting that animals can detect chemical features of the particles and/or their breakdown products and actively avoid areas with them. These results will help to understand how specific, chemically-defined particles proposed for use in polluted soil and wastewater remediation affect animal toxicity and behaviors in their natural environment.
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Affiliation(s)
- Catherine J Munro
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Michelle A Nguyen
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Christian Falgons
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Sana Chaudhry
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Mary Olagunjo
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Addys Bode
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Carla Bobé
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Manuel E Portela
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Marc R Knecht
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
| | - Kevin M Collins
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA
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21
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Moreno-Salinas AL, Avila-Zozaya M, Ugalde-Silva P, Hernández-Guzmán DA, Missirlis F, Boucard AA. Latrophilins: A Neuro-Centric View of an Evolutionary Conserved Adhesion G Protein-Coupled Receptor Subfamily. Front Neurosci 2019; 13:700. [PMID: 31354411 PMCID: PMC6629964 DOI: 10.3389/fnins.2019.00700] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 06/20/2019] [Indexed: 12/21/2022] Open
Abstract
The adhesion G protein-coupled receptors latrophilins have been in the limelight for more than 20 years since their discovery as calcium-independent receptors for α-latrotoxin, a spider venom toxin with potent activity directed at neurotransmitter release from a variety of synapse types. Latrophilins are highly expressed in the nervous system. Although a substantial amount of studies has been conducted to describe the role of latrophilins in the toxin-mediated action, the recent identification of endogenous ligands for these receptors helped confirm their function as mediators of adhesion events. Here we hypothesize a role for latrophilins in inter-neuronal contacts and the formation of neuronal networks and we review the most recent information on their role in neurons. We explore molecular, cellular and behavioral aspects related to latrophilin adhesion function in mice, zebrafish, Drosophila melanogaster and Caenorhabditis elegans, in physiological and pathophysiological conditions, including autism spectrum, bipolar, attention deficit and hyperactivity and substance use disorders.
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Affiliation(s)
- Ana L. Moreno-Salinas
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City, Mexico
| | - Monserrat Avila-Zozaya
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City, Mexico
| | - Paul Ugalde-Silva
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City, Mexico
| | - David A. Hernández-Guzmán
- Department of Physiology, Biophysics and Neurosciences, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City, Mexico
| | - Fanis Missirlis
- Department of Physiology, Biophysics and Neurosciences, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City, Mexico
| | - Antony A. Boucard
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City, Mexico
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22
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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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23
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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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24
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Brewer JC, Olson AC, Collins KM, Koelle MR. Serotonin and neuropeptides are both released by the HSN command neuron to initiate Caenorhabditis elegans egg laying. PLoS Genet 2019; 15:e1007896. [PMID: 30677018 PMCID: PMC6363226 DOI: 10.1371/journal.pgen.1007896] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 02/05/2019] [Accepted: 12/13/2018] [Indexed: 01/03/2023] Open
Abstract
Neurons typically release both a small-molecule neurotransmitter and one or more neuropeptides, but how these two types of signal from the same neuron might act together remains largely obscure. For example, serotonergic neurons in mammalian brain express the neuropeptide Substance P, but it is unclear how this co-released neuropeptide might modulate serotonin signaling. We studied this issue in C. elegans, in which all serotonergic neurons express the neuropeptide NLP-3. The serotonergic Hermaphrodite Specific Neurons (HSNs) are command motor neurons within the egg-laying circuit which have been shown to release serotonin to initiate egg-laying behavior. We found that egg-laying defects in animals lacking serotonin were far milder than in animals lacking HSNs, suggesting that HSNs must release other signal(s) in addition to serotonin to stimulate egg laying. While null mutants for nlp-3 had only mild egg-laying defects, animals lacking both serotonin and NLP-3 had severe defects, similar to those of animals lacking HSNs. Optogenetic activation of HSNs induced egg laying in wild-type animals, and in mutant animals lacking either serotonin or NLP-3, but failed to induce egg laying in animals lacking both. We recorded calcium activity in the egg-laying muscles of animals lacking either serotonin, NLP-3, or both. The single mutants, and to a greater extent the double mutant, showed muscle activity that was uncoordinated and unable to expel eggs. Specifically, the vm2 muscles cells, which are direct postsynaptic targets of the HSN, failed to contract simultaneously with other egg-laying muscle cells. Our results show that the HSN neurons use serotonin and the neuropeptide NLP-3 as partially redundant co-transmitters that together stimulate and coordinate activity of the target cells onto which they are released. Activity of the brain results from neurons communicating with each other using chemical signals. A typical neuron releases two kinds of chemical signals: a small molecule neurotransmitter, such as serotonin, and one or more small proteins, called neuropeptides. For example, neurons in the human brain that release serotonin, a neurotransmitter thought to be involved in depression, also release the neuropeptide Substance P. Neuroscientists have typically studied the effects of neurotransmitters and neuropeptides separately, without considering how these two types of signals from the same neuron might be integrated. Here we analyzed how specific neurons in the model organism C. elegans use both serotonin and a neuropeptide together. The Hermaphrodite Specific Neurons (HSNs) activate a small group of neurons and muscles to generate egg-laying behavior. Killing the HSNs resulted in animals unable to lay eggs, but we found that eliminating either serotonin or the neuropeptide resulted in HSNs that still remained able to activate egg laying. However, eliminating both serotonin and the neuropeptide resulted in HSNs unable to activate coordinated contractions of the egg-laying muscles. Our results show that in a living animal, serotonin acts in concert with a co-released neuropeptide to carry out its functions.
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Affiliation(s)
- Jacob C. Brewer
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Andrew C. Olson
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Kevin M. Collins
- Department of Biology, University of Miami, Coral Gables, Florida, United States of America
| | - Michael R. Koelle
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
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25
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White J. Clues to basis of exploratory behaviour of the C. elegans snout from head somatotropy. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2017.0367. [PMID: 30201833 DOI: 10.1098/rstb.2017.0367] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2018] [Indexed: 12/16/2022] Open
Abstract
Wave propagation during locomotory movements of Caenorhabditis elegans is constrained to a single dorso/ventral plane. By contrast, the tip of the head (snout) can make rapid exploratory movements in all directions relative to the body axis. These extra degrees of freedom are probably important for animals to seek and identify desirable passages in the interstices of the three-dimensional matrix of soil particles, their usual habitat. The differences in degrees of freedom of movement between snout and body are reflected in the innervation of the musculature. Along the length of the body, the two quadrants of dorsal muscle receive common innervation as do the two quadrants of ventral muscle. By contrast, muscles in the snout have an octagonal arrangement of innervation. It is likely that the exploratory behaviour of the snout is mediated by octant-specific motor and sensory neurons, together with their associated interneurons. The well-defined anatomical structure and neural circuitry of the snout together with behavioural observations should facilitate the implementation of models of the neural basis of exploratory movements, which could lead to an understanding of the basis of this relatively complex behaviour, a behaviour that has similarities to foraging in some vertebrates.This article is part of a discussion meeting issue 'Connectome to behaviour: modelling C. elegans at cellular resolution'.
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Affiliation(s)
- John White
- Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, WI, USA
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26
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De Magalhaes Filho CD, Henriquez B, Seah NE, Evans RM, Lapierre LR, Dillin A. Visible light reduces C. elegans longevity. Nat Commun 2018; 9:927. [PMID: 29500338 PMCID: PMC5834526 DOI: 10.1038/s41467-018-02934-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/09/2018] [Indexed: 12/19/2022] Open
Abstract
The transparent nematode Caenorhabditis elegans can sense UV and blue-violet light to alter behavior. Because high-dose UV and blue-violet light are not a common feature outside of the laboratory setting, we asked what role, if any, could low-intensity visible light play in C. elegans physiology and longevity. Here, we show that C. elegans lifespan is inversely correlated to the time worms were exposed to visible light. While circadian control, lite-1 and tax-2 do not contribute to the lifespan reduction, we demonstrate that visible light creates photooxidative stress along with a general unfolded-protein response that decreases the lifespan. Finally, we find that long-lived mutants are more resistant to light stress, as well as wild-type worms supplemented pharmacologically with antioxidants. This study reveals that transparent nematodes are sensitive to visible light radiation and highlights the need to standardize methods for controlling the unrecognized biased effect of light during lifespan studies in laboratory conditions.
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Affiliation(s)
- C Daniel De Magalhaes Filho
- The Howard Hughes Medical Institute, Molecular and Cell Biology Department, Li Ka Shing Center, University of California Berkeley, Berkeley, CA, 94720, USA
- The Salk Institute for Biological Studies, Gene expression laboratory, The Howard Hughes Medical Institute, 10010 N.Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Brian Henriquez
- The Salk Institute for Biological Studies, Gene expression laboratory, The Howard Hughes Medical Institute, 10010 N.Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Nicole E Seah
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02912, USA
| | - Ronald M Evans
- The Salk Institute for Biological Studies, Gene expression laboratory, The Howard Hughes Medical Institute, 10010 N.Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Louis R Lapierre
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02912, USA
| | - Andrew Dillin
- The Howard Hughes Medical Institute, Molecular and Cell Biology Department, Li Ka Shing Center, University of California Berkeley, Berkeley, CA, 94720, USA.
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Optical silencing of body wall muscles induces pumping inhibition in Caenorhabditis elegans. PLoS Genet 2017; 13:e1007134. [PMID: 29281635 PMCID: PMC5760098 DOI: 10.1371/journal.pgen.1007134] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 01/09/2018] [Accepted: 11/28/2017] [Indexed: 01/08/2023] Open
Abstract
Feeding, a vital behavior in animals, is modulated depending on internal and external factors. In the nematode Caenorhabditis elegans, the feeding organ called the pharynx ingests food by pumping driven by the pharyngeal muscles. Here we report that optical silencing of the body wall muscles, which drive the locomotory movement of worms, affects pumping. In worms expressing the Arch proton pump or the ACR2 anion channel in the body wall muscle cells, the pumping rate decreases after activation of Arch or ACR2 with light illumination, and recovers gradually after terminating illumination. Pumping was similarly inhibited by illumination in locomotion-defective mutants carrying Arch, suggesting that perturbation of locomotory movement is not critical for pumping inhibition. Analysis of mutants and cell ablation experiments showed that the signals mediating the pumping inhibition response triggered by activation of Arch with weak light are transferred mainly through two pathways: one involving gap junction-dependent mechanisms through pharyngeal I1 neurons, which mediate fast signals, and the other involving dense-core vesicle-dependent mechanisms, which mediate slow signals. Activation of Arch with strong light inhibited pumping strongly in a manner that does not rely on either gap junction-dependent or dense-core vesicle-dependent mechanisms. Our study revealed a new aspect of the neural and neuroendocrine controls of pumping initiated from the body wall muscles. Since feeding is an essential behavior for the survival of animals, it is modulated by a variety of neural and neuroendocrine signals that are generated depending on internal and external conditions. To elucidate the cellular and molecular mechanisms underlying the regulation of feeding, the nematode Caenorhabditis elegans, which is composed of a small number of identifiable cells, provides a unique system. In C. elegans, the pumping movement of a feeding organ called the pharynx has been subjected to intensive genetic studies. Compared to the factors promoting pumping, however, the inhibitory mechanisms of pumping are less well understood. In this paper, we report that optogenetic silencing of the body wall muscles, which drive the locomotory movement of worms, inhibits pumping in the pharynx. Signals emanating from muscles are likely to trigger pumping inhibition, raising an interesting possibility that the proprioceptive sense detecting the relaxation of body wall muscles might be involved. When the Arch proton pump was activated with weak light, signals for pumping inhibition are transferred into the pharynx mainly through two pathways: one involving gap junction-dependent mechanisms through pharyngeal I1 neurons, which mediate fast signals, and the other involving dense-core vesicle-dependent mechanisms, which mediate slow signals. Strong activation of Arch inhibits pumping very strongly via other mechanisms. Thus, we have revealed a new link between pumping and the body wall muscles, and confirmed the important cooperation of neural and neuroendocrine circuits in the regulation of feeding behaviors.
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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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29
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Olah Z, Bush AI, Aleksza D, Galik B, Ivitz E, Macsai L, Janka Z, Karman Z, Kalman J, Datki Z. Novel in vivo experimental viability assays with high sensitivity and throughput capacity using a bdelloid rotifer. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 144:115-122. [PMID: 28605645 DOI: 10.1016/j.ecoenv.2017.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 05/29/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Rotifers have been used in biological research as well-characterized models of aging. Their multi-organ characters and their sensitivity for chemicals and environmental changes make them useful as in vivo toxicological and lifespan models. Our aim was to create a bdelloid rotifer model to use in high-throughput viability and non-invasive assays. In order to identify our species Philodina acuticornis odiosa (PA), 18S rDNA-based phylogenetic analysis was carried out and their species-specific morphological markers identified. To execute the rotifer-based experiments, we developed an oil-covered water-drop methodology adapted from human in vitro fertilization techniques. This enables toxicological observations of individual one-housed rotifers in a closed and controllable micro-environment for up to several weeks. Hydrogen peroxide (H2O2) and sodium azide (NaN3) exposures were used as well-understood toxins. The toxicity and survival lifespan (TSL), the bright light disturbance (BLD) the mastax contraction frequency (MCF) and the cellular reduction capacity (CRC), indices were recorded. These newly developed assays were used to test the effects of lethal and sublethal doses of the toxins. The results showed the expected dose-dependent decrease in indices. These four different assays can either be used independently or as an integrated system for studying rotifers. These new indices render the PA invertebrate rotifer model a quantitative system for measuring viability, toxicity and lifespan (with TSL), systemic reaction capacity (with BLD), organic functionality (with MCF) and reductive capability of rotifers (with CRC), in vivo. This novel multi-level system is a reliable, sensitive and replicable screening tool with potential application in pharmaceutical science.
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Affiliation(s)
- Zita Olah
- Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Ashley I Bush
- Oxidation Biology Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - David Aleksza
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - Bence Galik
- Bioinformatics & Scientific Computing, Vienna Biocenter Core Facilities, Vienna, Austria
| | - Eszter Ivitz
- Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Lilla Macsai
- Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Zoltan Janka
- Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Zoltan Karman
- Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Janos Kalman
- Department of Psychiatry, University of Szeged, Szeged, Hungary
| | - Zsolt Datki
- Department of Psychiatry, University of Szeged, Szeged, Hungary.
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30
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Ohno H, Yoshida M, Sato T, Kato J, Miyazato M, Kojima M, Ida T, Iino Y. Luqin-like RYamide peptides regulate food-evoked responses in C. elegans. eLife 2017; 6:e28877. [PMID: 28847365 PMCID: PMC5576490 DOI: 10.7554/elife.28877] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/08/2017] [Indexed: 12/25/2022] Open
Abstract
Peptide signaling controls many processes involving coordinated actions of multiple organs, such as hormone-mediated appetite regulation. However, the extent to which the mode of action of peptide signaling is conserved in different animals is largely unknown, because many peptides and receptors remain orphan and many undiscovered peptides still exist. Here, we identify two novel Caenorhabditis elegans neuropeptides, LURY-1-1 and LURY-1-2, as endogenous ligands for the neuropeptide receptor-22 (NPR-22). Both peptides derive from the same precursor that is orthologous to invertebrate luqin/arginine-tyrosine-NH2 (RYamide) proneuropeptides. LURY-1 peptides are secreted from two classes of pharyngeal neurons and control food-related processes: feeding, lifespan, egg-laying, and locomotory behavior. We propose that LURY-1 peptides transmit food signals to NPR-22 expressed in feeding pacemaker neurons and a serotonergic neuron. Our results identified a critical role for luqin-like RYamides in feeding-related processes and suggested that peptide-mediated negative feedback is important for satiety regulation in C. elegans.
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Affiliation(s)
- Hayao Ohno
- Department of Biological SciencesGraduate School of Science, The University of TokyoTokyoJapan
| | - Morikatsu Yoshida
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research InstituteOsakaJapan
| | - Takahiro Sato
- Molecular GeneticsInstitute of Life Sciences, Kurume UniversityFukuokaJapan
| | - Johji Kato
- Department of Bioactive PeptidesFrontier Science Research Center, University of MiyazakiMiyazakiJapan
| | - Mikiya Miyazato
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research InstituteOsakaJapan
| | - Masayasu Kojima
- Molecular GeneticsInstitute of Life Sciences, Kurume UniversityFukuokaJapan
| | - Takanori Ida
- Department of Bioactive PeptidesFrontier Science Research Center, University of MiyazakiMiyazakiJapan
- Center for Animal Disease ControlUniversity of MiyazakiMiyazakiJapan
| | - Yuichi Iino
- Department of Biological SciencesGraduate School of Science, The University of TokyoTokyoJapan
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31
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Schröter M, Paulsen O, Bullmore ET. Micro-connectomics: probing the organization of neuronal networks at the cellular scale. Nat Rev Neurosci 2017; 18:131-146. [PMID: 28148956 DOI: 10.1038/nrn.2016.182] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Defining the organizational principles of neuronal networks at the cellular scale, or micro-connectomics, is a key challenge of modern neuroscience. In this Review, we focus on graph theoretical parameters of micro-connectome topology, often informed by economical principles that conceptually originated with Ramón y Cajal's conservation laws. First, we summarize results from studies in intact small organisms and in samples from larger nervous systems. We then evaluate the evidence for an economical trade-off between biological cost and functional value in the organization of neuronal networks. Various results suggest that many aspects of neuronal network organization are indeed the outcome of competition between these two fundamental selection pressures.
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Affiliation(s)
- Manuel Schröter
- Department of Psychiatry and Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0SZ, UK.,Department of Biosystems Science and Engineering, Bio Engineering Laboratory, ETH Zurich, Mattenstrasse 26, Basel CH-4058, Switzerland
| | - Ole Paulsen
- Department of Physiology, Development and Neuroscience, University of Cambridge, Physiological Laboratory, Downing Street, Cambridge CB2 3EG, UK
| | - Edward T Bullmore
- Department of Psychiatry and Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0SZ, UK.,ImmunoPsychiatry, Immuno-Inflammation Therapeutic Area Unit, GlaxoSmithKline R&D, Stevenage SG1 2NY, UK.,Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge Road, Fulbourn, Cambridge CB21 5HH, UK
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32
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Petrushin A, Ferrara L, Blau A. The Si elegans project at the interface of experimental and computational Caenorhabditis elegans neurobiology and behavior. J Neural Eng 2016; 13:065001. [PMID: 27739402 DOI: 10.1088/1741-2560/13/6/065001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE In light of recent progress in mapping neural function to behavior, we briefly and selectively review past and present endeavors to reveal and reconstruct nervous system function in Caenorhabditis elegans through simulation. APPROACH Rather than presenting an all-encompassing review on the mathematical modeling of C. elegans, this contribution collects snapshots of pathfinding key works and emerging technologies that recent single- and multi-center simulation initiatives are building on. We thereby point out a few general limitations and problems that these undertakings are faced with and discuss how these may be addressed and overcome. MAIN RESULTS Lessons learned from past and current computational approaches to deciphering and reconstructing information flow in the C. elegans nervous system corroborate the need of refining neural response models and linking them to intra- and extra-environmental interactions to better reflect and understand the actual biological, biochemical and biophysical events that lead to behavior. Together with single-center research efforts, the Si elegans and OpenWorm projects aim at providing the required, in some cases complementary tools for different hardware architectures to support advancement into this direction. SIGNIFICANCE Despite its seeming simplicity, the nervous system of the hermaphroditic nematode C. elegans with just 302 neurons gives rise to a rich behavioral repertoire. Besides controlling vital functions (feeding, defecation, reproduction), it encodes different stimuli-induced as well as autonomous locomotion modalities (crawling, swimming and jumping). For this dichotomy between system simplicity and behavioral complexity, C. elegans has challenged neurobiologists and computational scientists alike. Understanding the underlying mechanisms that lead to a context-modulated functionality of individual neurons would not only advance our knowledge on nervous system function and its failure in pathological states, but have directly exploitable benefits for robotics and the engineering of brain-mimetic computational architectures that are orthogonal to current von-Neumann-type machines.
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Affiliation(s)
- Alexey Petrushin
- Dept. of Neuroscience and Brain Technologies (NBT), Italian Institute of Technology (IIT), 16163 Genoa, Italy
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33
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Weeks JC, Roberts WM, Robinson KJ, Keaney M, Vermeire JJ, Urban JF, Lockery SR, Hawdon JM. Microfluidic platform for electrophysiological recordings from host-stage hookworm and Ascaris suum larvae: A new tool for anthelmintic research. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2016; 6:314-328. [PMID: 27751868 PMCID: PMC5196495 DOI: 10.1016/j.ijpddr.2016.08.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/17/2016] [Accepted: 08/17/2016] [Indexed: 12/27/2022]
Abstract
The screening of candidate compounds and natural products for anthelmintic activity is important for discovering new drugs against human and animal parasites. We previously validated in Caenorhabditis elegans a microfluidic device (‘chip’) that records non-invasively the tiny electrophysiological signals generated by rhythmic contraction (pumping) of the worm's pharynx. These electropharyngeograms (EPGs) are recorded simultaneously from multiple worms per chip, providing a medium-throughput readout of muscular and neural activity that is especially useful for compounds targeting neurotransmitter receptors and ion channels. Microfluidic technologies have transformed C. elegans research and the goal of the current study was to validate hookworm and Ascaris suum host-stage larvae in the microfluidic EPG platform. Ancylostoma ceylanicum and A. caninum infective L3s (iL3s) that had been activated in vitro generally produced erratic EPG activity under the conditions tested. In contrast, A. ceylanicum L4s recovered from hamsters exhibited robust, sustained EPG activity, consisting of three waveforms: (1) conventional pumps as seen in other nematodes; (2) rapid voltage deflections, associated with irregular contractions of the esophagus and openings of the esophogeal-intestinal valve (termed a ‘flutter’); and (3) hybrid waveforms, which we classified as pumps. For data analysis, pumps and flutters were combined and termed EPG ‘events.’ EPG waveform identification and analysis were performed semi-automatically using custom-designed software. The neuromodulator serotonin (5-hydroxytryptamine; 5HT) increased EPG event frequency in A. ceylanicum L4s at an optimal concentration of 0.5 mM. The anthelmintic drug ivermectin (IVM) inhibited EPG activity in a concentration-dependent manner. EPGs from A. suum L3s recovered from pig lungs exhibited robust pharyngeal pumping in 1 mM 5HT, which was inhibited by IVM. These experiments validate the use of A. ceylanicum L4s and A. suum L3s with the microfluidic EPG platform, providing a new tool for screening anthelmintic candidates or investigating parasitic nematode feeding behavior. Pharyngeal pumping in nematodes generates an electropharyngeogram (EPG). The EPG provides a readout of the electrical activity of neurons and muscles. A microfluidic platform for recording EPGs was validated in parasitic nematodes. EPG activity and drug responses were characterized in host-stage larvae. Microfluidic EPG recordings provide a powerful new tool for anthelmintic research.
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Affiliation(s)
- Janis C Weeks
- Institute of Neuroscience and African Studies Program, 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.
| | - Kristin J Robinson
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR 97403-1254, USA.
| | - Melissa Keaney
- Department of Microbiology, Immunology, and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA.
| | - Jon J Vermeire
- Center for Discovery and Innovation in Parasitic Diseases, Dept. of Pathology and Laboratory Medicine, UC, San Francisco, USA.
| | - Joseph F Urban
- US Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomic and Immunology Laboratory, Beltsville, MD, USA.
| | - Shawn R Lockery
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR 97403-1254, USA.
| | - John M Hawdon
- Department of Microbiology, Immunology, and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20037, USA.
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34
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Abstract
The new field of connectomics aims to obtain fine-grained anatomical connectivity data for vertebrate brains. A recent study highlights the types of experiments that will be necessary in order to draw conclusions about function from anatomical connectivity.
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Affiliation(s)
- Nicholas F Trojanowski
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David M Raizen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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35
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Trojanowski NF, Raizen DM, Fang-Yen C. Pharyngeal pumping in Caenorhabditis elegans depends on tonic and phasic signaling from the nervous system. Sci Rep 2016; 6:22940. [PMID: 26976078 PMCID: PMC4791602 DOI: 10.1038/srep22940] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/23/2016] [Indexed: 02/02/2023] Open
Abstract
Rhythmic movements are ubiquitous in animal locomotion, feeding, and circulatory systems. In some systems, the muscle itself generates rhythmic contractions. In others, rhythms are generated by the nervous system or by interactions between the nervous system and muscles. In the nematode Caenorhabditis elegans, feeding occurs via rhythmic contractions (pumping) of the pharynx, a neuromuscular feeding organ. Here, we use pharmacology, optogenetics, genetics, and electrophysiology to investigate the roles of the nervous system and muscle in generating pharyngeal pumping. Hyperpolarization of the nervous system using a histamine-gated chloride channel abolishes pumping, and optogenetic stimulation of pharyngeal muscle in these animals causes abnormal contractions, demonstrating that normal pumping requires nervous system function. In mutants that pump slowly due to defective nervous system function, tonic muscle stimulation causes rapid pumping, suggesting tonic neurotransmitter release may regulate pumping. However, tonic cholinergic motor neuron stimulation, but not tonic muscle stimulation, triggers pumps that electrophysiologically resemble typical rapid pumps. This suggests that pharyngeal cholinergic motor neurons are normally rhythmically, and not tonically active. These results demonstrate that the pharynx generates a myogenic rhythm in the presence of tonically released acetylcholine, and suggest that the pharyngeal nervous system entrains contraction rate and timing through phasic neurotransmitter release.
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Affiliation(s)
- Nicholas F Trojanowski
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA.,Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, 19104 PA, USA.,Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA
| | - David M Raizen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA
| | - Christopher Fang-Yen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, 19104 PA, USA.,Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA
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