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Wolstenholme AJ, Andersen EC, Choudhary S, Ebner F, Hartmann S, Holden-Dye L, Kashyap SS, Krücken J, Martin RJ, Midha A, Nejsum P, Neveu C, Robertson AP, von Samson-Himmelstjerna G, Walker R, Wang J, Whitehead BJ, Williams PDE. Getting around the roundworms: Identifying knowledge gaps and research priorities for the ascarids. ADVANCES IN PARASITOLOGY 2024; 123:51-123. [PMID: 38448148 PMCID: PMC11143470 DOI: 10.1016/bs.apar.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The ascarids are a large group of parasitic nematodes that infect a wide range of animal species. In humans, they cause neglected diseases of poverty; many animal parasites also cause zoonotic infections in people. Control measures include hygiene and anthelmintic treatments, but they are not always appropriate or effective and this creates a continuing need to search for better ways to reduce the human, welfare and economic costs of these infections. To this end, Le Studium Institute of Advanced Studies organized a two-day conference to identify major gaps in our understanding of ascarid parasites with a view to setting research priorities that would allow for improved control. The participants identified several key areas for future focus, comprising of advances in genomic analysis and the use of model organisms, especially Caenorhabditis elegans, a more thorough appreciation of the complexity of host-parasite (and parasite-parasite) communications, a search for novel anthelmintic drugs and the development of effective vaccines. The participants agreed to try and maintain informal links in the future that could form the basis for collaborative projects, and to co-operate to organize future meetings and workshops to promote ascarid research.
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Affiliation(s)
- Adrian J Wolstenholme
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Université de Tours, ISP, Nouzilly, France.
| | - Erik C Andersen
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Shivani Choudhary
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Friederike Ebner
- Department of Molecular Life Sciences, School of Life Sciences, Technische Universität München, Freising, Germany
| | - Susanne Hartmann
- Institute for Immunology, Freie Universität Berlin, Berlin, Germany
| | - Lindy Holden-Dye
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Sudhanva S Kashyap
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Richard J Martin
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Ankur Midha
- Institute for Immunology, Freie Universität Berlin, Berlin, Germany
| | - Peter Nejsum
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Cedric Neveu
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Université de Tours, ISP, Nouzilly, France
| | - Alan P Robertson
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | | | - Robert Walker
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Jianbin Wang
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, United States
| | | | - Paul D E Williams
- Department of Biomedical Sciences, Iowa State University, Ames, IA, United States
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2
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Funayama T, Suzuki M, Miyawaki N, Kashiwagi H. A Method to Locally Irradiate Specific Organ in Model Organisms Using a Focused Heavy-Ion Microbeam. BIOLOGY 2023; 12:1524. [PMID: 38132350 PMCID: PMC10740561 DOI: 10.3390/biology12121524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/06/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023]
Abstract
The functions of organisms are performed by various tissues composed of different cell types. Localized irradiation with heavy-ion microbeams, which inactivate only a portion of the constituent cells without destroying the physical intercellular connections of the tissue, is a practical approach for elucidating tissue functions. However, conventional collimated microbeams are limited in the shape of the area that can be irradiated. Therefore, using a focused heavy-ion microbeam that generates a highly precise beam spot, we developed a technology to uniformly irradiate specific tissues of an organism with a defined dose, which conventional methods cannot achieve. The performance of the developed paint irradiation technology was evaluated. By irradiating the CR-39 ion track detector, we confirmed that the new method, in which each ion hit position is placed uniformly in the irradiated area, makes it possible to uniformly paint the area at a specified dose. The targeted irradiation of the pharynx and gonads of living Caenorhabditis elegans demonstrated that the irradiated ions were distributed in the same shape as the targeted tissue observed under a microscope. This technology will elucidate biological mechanisms that are difficult to analyze with conventional collimated microbeam irradiation.
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Affiliation(s)
- Tomoo Funayama
- Takasaki Institute for Advanced Quantum Science (TIAQ), National Institutes for Quantum Science and Technology (QST), Gunma 370-1292, Japan; (M.S.); (N.M.); (H.K.)
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3
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Wang Y, Guo K, Wang Q, Zhong G, Zhang W, Jiang Y, Mao X, Li X, Huang Z. Caenorhabditis elegans as an emerging model in food and nutrition research: importance of standardizing base diet. Crit Rev Food Sci Nutr 2022; 64:3167-3185. [PMID: 36200941 DOI: 10.1080/10408398.2022.2130875] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
As a model organism that has helped revolutionize life sciences, Caenorhabditis elegans has been increasingly used in nutrition research. Here we explore the tradeoffs between pros and cons of its use as a dietary model based primarily on literature review from the past decade. We first provide an overview of its experimental strengths as an animal model, focusing on lifespan and healthspan, behavioral and physiological phenotypes, and conservation of key nutritional pathways. We then summarize recent advances of its use in nutritional studies, e.g. food preference and feeding behavior, sugar status and metabolic reprogramming, lifetime and transgenerational nutrition tracking, and diet-microbiota-host interactions, highlighting cutting-edge technologies originated from or developed in C. elegans. We further review current challenges of using C. elegans as a nutritional model, followed by in-depth discussions on potential solutions. In particular, growth scales and throughputs, food uptake mode, and axenic culture of C. elegans are appraised in the context of food research. We also provide perspectives for future development of chemically defined nematode food ("NemaFood") for C. elegans, which is now widely accepted as a versatile and affordable in vivo model and has begun to show transformative potential to pioneer nutrition science.
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Affiliation(s)
- Yuqing Wang
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
| | - Kaixin Guo
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Qiangqiang Wang
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
| | - Guohuan Zhong
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Center for Bioresources and Drug Discovery, School of Biosciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Wenjun Zhang
- Center for Bioresources and Drug Discovery, School of Biosciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yiyi Jiang
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Perfect Life & Health Institute, Zhongshan, Guangdong, China
| | - Xinliang Mao
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Perfect Life & Health Institute, Zhongshan, Guangdong, China
| | - Xiaomin Li
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Perfect Life & Health Institute, Zhongshan, Guangdong, China
| | - Zebo Huang
- Institute for Food Nutrition and Human Health, School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Guangdong Province Key Laboratory for Biocosmetics, Guangzhou, China
- Center for Bioresources and Drug Discovery, School of Biosciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
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4
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Hahnel SR, Roberts WM, Heisler I, Kulke D, Weeks JC. Comparison of electrophysiological and motility assays to study anthelmintic effects in Caenorhabditis elegans. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2021; 16:174-187. [PMID: 34252686 PMCID: PMC8350797 DOI: 10.1016/j.ijpddr.2021.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/15/2021] [Accepted: 05/20/2021] [Indexed: 12/14/2022]
Abstract
Currently, only a few chemical drug classes are available to control the global burden of nematode infections in humans and animals. Most of these drugs exert their anthelmintic activity by interacting with proteins such as ion channels, and the nematode neuromuscular system remains a promising target for novel intervention strategies. Many commonly-used phenotypic readouts such as motility provide only indirect insight into neuromuscular function and the site(s) of action of chemical compounds. Electrophysiological recordings provide more specific information but are typically technically challenging and lack high throughput for drug discovery. Because drug discovery relies strongly on the evaluation and ranking of drug candidates, including closely related chemical derivatives, precise assays and assay combinations are needed for capturing and distinguishing subtle drug effects. Past studies show that nematode motility and pharyngeal pumping (feeding) are inhibited by most anthelmintic drugs. Here we compare two microfluidic devices (“chips”) that record electrophysiological signals from the nematode pharynx (electropharyngeograms; EPGs) ─ the ScreenChip™ and the 8-channel EPG platform ─ to evaluate their respective utility for anthelmintic research. We additionally compared EPG data with whole-worm motility measurements obtained with the wMicroTracker instrument. As references, we used three macrocyclic lactones (ivermectin, moxidectin, and milbemycin oxime), and levamisole, which act on different ion channels. Drug potencies (IC50 and IC95 values) from concentration-response curves, and the time-course of drug effects, were compared across platforms and across drugs. Drug effects on pump timing and EPG waveforms were also investigated. These experiments confirmed drug-class specific effects of the tested anthelmintics and illustrated the relative strengths and limitations of the different assays for anthelmintic research. Anthelmintic drugs inhibit pharyngeal pumping and motility in C. elegans. Two electrophysiological assays and one motility assay were compared. Macrocyclic lactones and levamisole have drug-class-specific effects. A combination of assays most fully reveals anthelmintic effects. Strengths and limitations of the three assays were identified.
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Affiliation(s)
| | | | | | | | - Janis C Weeks
- InVivo Biosystems Inc. (formerly NemaMetrix Inc.), Eugene, OR, USA.
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5
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Meng L, Yan D. NLR-1/CASPR Anchors F-Actin to Promote Gap Junction Formation. Dev Cell 2020; 55:574-587.e3. [PMID: 33238150 DOI: 10.1016/j.devcel.2020.10.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/05/2020] [Accepted: 10/28/2020] [Indexed: 12/31/2022]
Abstract
Gap junctions are present in most tissues and play essential roles in various biological processes. However, we know surprisingly little about the molecular mechanisms underlying gap junction formation. Here, we uncover the essential role of a conserved EGF- and laminin-G-domain-containing protein nlr-1/CASPR in the regulation of gap junction formation in multiple tissues across different developmental stages in C. elegans. NLR-1 is located in the gap junction perinexus, a region adjacent to but not overlapping with gap junctions, and forms puncta before the clusters of gap junction channels appear on the membrane. We show that NLR-1 can directly bind to actin to recruit F-actin networks at the gap junction formation plaque, and the formation of F-actin patches plays a critical role in the assembly of gap junction channels. Our findings demonstrate that nlr-1/CASPR acts as an early stage signal for gap junction formation through anchoring of F-actin networks.
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Affiliation(s)
- Lingfeng Meng
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Dong Yan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Regeneration Next, and Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC 27710, USA.
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6
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Klimovich A, Giacomello S, Björklund Å, Faure L, Kaucka M, Giez C, Murillo-Rincon AP, Matt AS, Willoweit-Ohl D, Crupi G, de Anda J, Wong GCL, D'Amato M, Adameyko I, Bosch TCG. Prototypical pacemaker neurons interact with the resident microbiota. Proc Natl Acad Sci U S A 2020; 117:17854-17863. [PMID: 32647059 PMCID: PMC7395494 DOI: 10.1073/pnas.1920469117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Pacemaker neurons exert control over neuronal circuit function by their intrinsic ability to generate rhythmic bursts of action potential. Recent work has identified rhythmic gut contractions in human, mice, and hydra to be dependent on both neurons and the resident microbiota. However, little is known about the evolutionary origin of these neurons and their interaction with microbes. In this study, we identified and functionally characterized prototypical ANO/SCN/TRPM ion channel-expressing pacemaker cells in the basal metazoan Hydra by using a combination of single-cell transcriptomics, immunochemistry, and functional experiments. Unexpectedly, these prototypical pacemaker neurons express a rich set of immune-related genes mediating their interaction with the microbial environment. Furthermore, functional experiments gave a strong support to a model of the evolutionary emergence of pacemaker cells as neurons using components of innate immunity to interact with the microbial environment and ion channels to generate rhythmic contractions.
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Affiliation(s)
- Alexander Klimovich
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany;
| | - Stefania Giacomello
- Department of Biochemistry and Biophysics, National Infrastructure of Sweden, Science for Life Laboratory, Stockholm University, 17121 Solna, Sweden
- Department of Gene Technology, Science for Life Laboratory, Kungligia Tekniska Högskolan Royal Institute of Technology, 17121 Solna, Sweden
| | - Åsa Björklund
- Department of Cell and Molecular Biology, National Infrastructure of Sweden, Science for Life Laboratory, Uppsala University, 75237 Uppsala, Sweden
| | - Louis Faure
- Department of Molecular Neurosciences, Center for Brain Research, Medical University Vienna, 1090 Vienna, Austria
| | - Marketa Kaucka
- Department of Molecular Neurosciences, Center for Brain Research, Medical University Vienna, 1090 Vienna, Austria
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, SH 24306 Plön, Germany
| | - Christoph Giez
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany
| | - Andrea P Murillo-Rincon
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany
| | - Ann-Sophie Matt
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany
| | - Doris Willoweit-Ohl
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany
| | - Gabriele Crupi
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany
| | - Jaime de Anda
- Department of Bioengineering, California NanoSystems Institute, University of California, Los Angeles, CA 90095-1600
- Department of Chemistry and Biochemistry, California NanoSystems Institute, University of California, Los Angeles, CA 90095-1600
| | - Gerard C L Wong
- Department of Bioengineering, California NanoSystems Institute, University of California, Los Angeles, CA 90095-1600
- Department of Chemistry and Biochemistry, California NanoSystems Institute, University of California, Los Angeles, CA 90095-1600
| | - Mauro D'Amato
- School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Igor Adameyko
- Department of Molecular Neurosciences, Center for Brain Research, Medical University Vienna, 1090 Vienna, Austria
- Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Thomas C G Bosch
- Department of Cell and Developmental Biology, Zoological Institute, University of Kiel, D-24118 Kiel, Germany;
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7
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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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8
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Weeks JC, Robinson KJ, Lockery SR, Roberts WM. Anthelmintic drug actions in resistant and susceptible C. elegans revealed by electrophysiological recordings in a multichannel microfluidic device. Int J Parasitol Drugs Drug Resist 2018; 8:607-628. [PMID: 30503202 PMCID: PMC6287544 DOI: 10.1016/j.ijpddr.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/17/2018] [Accepted: 10/18/2018] [Indexed: 12/22/2022]
Abstract
Many anthelmintic drugs used to treat parasitic nematode infections target proteins that regulate electrical activity of neurons and muscles: ion channels (ICs) and neurotransmitter receptors (NTRs). Perturbation of IC/NTR function disrupts worm behavior and can lead to paralysis, starvation, immune attack and expulsion. Limitations of current anthelmintics include a limited spectrum of activity across species and the threat of drug resistance, highlighting the need for new drugs for human and veterinary medicine. Although ICs/NTRs are valuable anthelmintic targets, electrophysiological recordings are not commonly included in drug development pipelines. We designed a medium-throughput platform for recording electropharyngeograms (EPGs)-the electrical signals emitted by muscles and neurons of the pharynx during pharyngeal pumping (feeding)-in Caenorhabditis elegans and parasitic nematodes. The current study in C. elegans expands previous work in several ways. Detecting anthelmintic bioactivity in drugs, compounds or natural products requires robust, sustained pharyngeal pumping under baseline conditions. We generated concentration-response curves for stimulating pumping by perfusing 8-channel microfluidic devices (chips) with the neuromodulator serotonin, or with E. coli bacteria (C. elegans' food in the laboratory). Worm orientation in the chip (head-first vs. tail-first) affected the response to E. coli but not to serotonin. Using a panel of anthelmintics-ivermectin, levamisole and piperazine-targeting different ICs/NTRs, we determined the effects of concentration and treatment duration on EPG activity, and successfully distinguished control (N2) and drug-resistant worms (avr-14; avr-15; glc-1, unc-38 and unc-49). EPG recordings detected anthelmintic activity of drugs that target ICs/NTRs located in the pharynx as well as at extra-pharyngeal sites. A bus-8 mutant with enhanced permeability was more sensitive than controls to drug treatment. These results provide a useful framework for investigators who would like to more easily incorporate electrophysiology as a routine component of their anthelmintic research workflow.
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Affiliation(s)
- Janis C Weeks
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - Kristin J Robinson
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - Shawn R Lockery
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
| | - William M Roberts
- Institute of Neuroscience, University of Oregon, 1254 University of Oregon, Eugene, OR, 97403-1254, USA.
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9
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Investigation of feeding behaviour in C. elegans reveals distinct pharmacological and antibacterial effects of nicotine. INVERTEBRATE NEUROSCIENCE 2018; 18:14. [DOI: 10.1007/s10158-018-0219-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 10/24/2018] [Indexed: 12/31/2022]
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10
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Kamireddy K, Chinnu S, Priyanka PS, Rajini PS, Giridhar P. Neuroprotective effect of Decalepis hamiltonii aqueous root extract and purified 2-hydroxy-4-methoxy benzaldehyde on 6-OHDA induced neurotoxicity in Caenorhabditis elegans. Biomed Pharmacother 2018; 105:997-1005. [PMID: 30021395 DOI: 10.1016/j.biopha.2018.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/01/2018] [Accepted: 06/02/2018] [Indexed: 01/01/2023] Open
Abstract
In this study, we investigated the possible neuroprotective efficacy of Decalepis hamiltonii tuber extract against 6-Hydroxy dopamine (6-OHDA) induced neurotoxicity and associated effects in Caenorhabditis elegans. The major component of flavour rich extract from D. hamiltonii is 2-hydroxy-4-methoxy benzaldehyde (2H4MB) which is an isomer of vanillin. We have conducted preliminary experiments with different types of extracts and subsequently DHFE (D. hamiltonii Fresh Tuber Extract) and DHPF (D. hamiltonii purified 2H4MB fraction) were used for further studies. Here we attempted to enumerate the neuroprotective efficacy of the above compounds in worms by evaluating behavioural and mitochondrial function, dopamine content and selective degeneration of dopaminergic neurons in BZ555 strains in comparison with control and 6-OHDA treated organisms. The relative expression levels of selected antioxidant genes involved in defence mechanism like SOD-3, GST-2 and GST-4 were evaluated along with those of CAT-2 and DOP-2 at mRNA level. We observed that both DHPF and DHFE exhibited significant levels of neuroprotective property against 6-OHDA induced neurotoxicity, which was evident in mitochondrial/dopaminergic function and antioxidant defence mechanism.
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Affiliation(s)
- Kiran Kamireddy
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India
| | - Salim Chinnu
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Food Protectants and Infestation Control Department, CSIR-CFTRI, Mysore, 570020, India
| | - P S Priyanka
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India
| | - P S Rajini
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Food Protectants and Infestation Control Department, CSIR-CFTRI, Mysore, 570020, India
| | - Parvatam Giridhar
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India.
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11
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Lucanic M, Garrett T, Yu I, Calahorro F, Asadi Shahmirzadi A, Miller A, Gill MS, Hughes RE, Holden‐Dye L, Lithgow GJ. Chemical activation of a food deprivation signal extends lifespan. Aging Cell 2016; 15:832-41. [PMID: 27220516 PMCID: PMC5013014 DOI: 10.1111/acel.12492] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2016] [Indexed: 12/29/2022] Open
Abstract
Model organisms subject to dietary restriction (DR) generally live longer. Accompanying this lifespan extension are improvements in overall health, based on multiple metrics. This indicates that pharmacological treatments that mimic the effects of DR could improve health in humans. To find new chemical structures that extend lifespan, we screened 30 000 synthetic, diverse drug‐like chemicals in Caenorhabditis elegans and identified several structurally related compounds that acted through DR mechanisms. The most potent of these NP1 impinges upon a food perception pathway by promoting glutamate signaling in the pharynx. This results in the overriding of a GPCR pathway involved in the perception of food and which normally acts to decrease glutamate signals. Our results describe the activation of a dietary restriction response through the pharmacological masking of a novel sensory pathway that signals the presence of food. This suggests that primary sensory pathways may represent novel targets for human pharmacology.
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Affiliation(s)
- Mark Lucanic
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Theo Garrett
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Ivan Yu
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
- Dominican University of California 50 Acacia Avenue San Rafael CA USA
| | - Fernando Calahorro
- Center for Biological Sciences Institute for Life Sciences University of Southampton Southampton UK
| | - Azar Asadi Shahmirzadi
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
- Davis School of Gerontology University of Southern California Los Angeles CA USA
| | - Aaron Miller
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Matthew S. Gill
- Department of Metabolism & Aging The Scripps Research Institute‐Scripps Florida 130 Scripps Way Jupiter FL 33458
| | - Robert E. Hughes
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
| | - Lindy Holden‐Dye
- Center for Biological Sciences Institute for Life Sciences University of Southampton Southampton UK
| | - Gordon J. Lithgow
- Buck Institute for Research on Aging 8001 Redwood Boulevard Novato CA USA
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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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Dillon J, Holden-Dye L, O'Connor V, Hopper NA. Context-dependent regulation of feeding behaviour by the insulin receptor, DAF-2, in Caenorhabditis elegans. INVERTEBRATE NEUROSCIENCE : IN 2016; 16:4. [PMID: 27209024 PMCID: PMC4875951 DOI: 10.1007/s10158-016-0187-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 04/13/2016] [Indexed: 12/31/2022]
Abstract
Insulin signalling plays a significant role in both developmental programmes and pathways modulating the neuronal signalling that controls adult behaviour. Here, we have investigated insulin signalling in food-associated behaviour in adult C. elegans by scoring locomotion and feeding on and off bacteria, the worm's food. This analysis used mutants (daf-2, daf-18) of the insulin signalling pathway, and we provide evidence for an acute role for insulin signalling in the adult nervous system distinct from its impact on developmental programmes. Insulin receptor daf-2 mutants move slower than wild type both on and off food and showed impaired locomotory responses to food deprivation. This latter behaviour is manifest as a failure to instigate dispersal following prolonged food deprivation and suggests a role for insulin signalling in this adaptive response. Insulin receptor daf-2 mutants are also deficient in pharyngeal pumping on food and off food. Pharmacological analysis showed the pharynx of daf-2 is selectively compromised in its response to 5-HT compared to the excitatory neuropeptide FLP-17. By comparing the adaptive pharyngeal behaviour in intact worms and isolated pharyngeal preparations, we determined that an insulin-dependent signal extrinsic to the pharyngeal system is involved in feeding adaptation. Hence, we suggest that reactive insulin signalling modulates both locomotory foraging and pharyngeal pumping as the animal adapts to the absence of food. We discuss this in the context of insulin signalling directing a shift in the sensitivity of neurotransmitter systems to regulate the worm's response to changes in food availability in the environment.
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Affiliation(s)
- James Dillon
- Centre for Biological Science, University of Southampton, Highfield Campus, University Road, Southampton, Hants, SO17 1BJ, UK.
| | - Lindy Holden-Dye
- Centre for Biological Science, University of Southampton, Highfield Campus, University Road, Southampton, Hants, SO17 1BJ, UK
| | - Vincent O'Connor
- Centre for Biological Science, University of Southampton, Highfield Campus, University Road, Southampton, Hants, SO17 1BJ, UK
| | - Neil A Hopper
- Centre for Biological Science, University of Southampton, Highfield Campus, University Road, Southampton, Hants, SO17 1BJ, UK
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14
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Dallière N, Bhatla N, Luedtke Z, Ma DK, Woolman J, Walker RJ, Holden-Dye L, O'Connor V. Multiple excitatory and inhibitory neural signals converge to fine-tune Caenorhabditis elegans feeding to food availability. FASEB J 2015; 30:836-48. [PMID: 26514165 DOI: 10.1096/fj.15-279257] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/13/2015] [Indexed: 01/02/2023]
Abstract
How an animal matches feeding to food availability is a key question for energy homeostasis. We addressed this in the nematode Caenorhabditis elegans, which couples feeding to the presence of its food (bacteria) by regulating pharyngeal activity (pumping). We scored pumping in the presence of food and over an extended time course of food deprivation in wild-type and mutant worms to determine the neural substrates of adaptive behavior. Removal of food initially suppressed pumping but after 2 h this was accompanied by intermittent periods of high activity. We show pumping is fine-tuned by context-specific neural mechanisms and highlight a key role for inhibitory glutamatergic and excitatory cholinergic/peptidergic drives in the absence of food. Additionally, the synaptic protein UNC-31 [calcium-activated protein for secretion (CAPS)] acts through an inhibitory pathway not explained by previously identified contributions of UNC-31/CAPS to neuropeptide or glutamate transmission. Pumping was unaffected by laser ablation of connectivity between the pharyngeal and central nervous system indicating signals are either humoral or intrinsic to the enteric system. This framework in which control is mediated through finely tuned excitatory and inhibitory drives resonates with mammalian hypothalamic control of feeding and suggests that fundamental regulation of this basic animal behavior may be conserved through evolution from nematode to human.
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Affiliation(s)
- Nicolas Dallière
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Nikhil Bhatla
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Zara Luedtke
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Dengke K Ma
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jonathan Woolman
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Robert J Walker
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lindy Holden-Dye
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Vincent O'Connor
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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15
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Schüler C, Fischer E, Shaltiel L, Steuer Costa W, Gottschalk A. Arrhythmogenic effects of mutated L-type Ca 2+-channels on an optogenetically paced muscular pump in Caenorhabditis elegans. Sci Rep 2015; 5:14427. [PMID: 26399900 PMCID: PMC4585839 DOI: 10.1038/srep14427] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/28/2015] [Indexed: 01/23/2023] Open
Abstract
Cardiac arrhythmias are often associated with mutations in ion channels or other proteins. To enable drug development for distinct arrhythmias, model systems are required that allow implementing patient-specific mutations. We assessed a muscular pump in Caenorhabditis elegans. The pharynx utilizes homologues of most of the ion channels, pumps and transporters defining human cardiac physiology. To yield precise rhythmicity, we optically paced the pharynx using channelrhodopsin-2. We assessed pharynx pumping by extracellular recordings (electropharyngeograms—EPGs), and by a novel video-microscopy based method we developed, which allows analyzing multiple animals simultaneously. Mutations in the L-type VGCC (voltage-gated Ca2+-channel) EGL-19 caused prolonged pump duration, as found for analogous mutations in the Cav1.2 channel, associated with long QT syndrome. egl-19 mutations affected ability to pump at high frequency and induced arrhythmicity. The pharyngeal neurons did not influence these effects. We tested whether drugs could ameliorate arrhythmia in the optogenetically paced pharynx. The dihydropyridine analog Nemadipine A prolonged pump duration in wild type, and reduced or prolonged pump duration of distinct egl-19 alleles, thus indicating allele-specific effects. In sum, our model may allow screening of drug candidates affecting specific VGCCs mutations, and permit to better understand the effects of distinct mutations on a macroscopic level.
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Affiliation(s)
- Christina Schüler
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany.,Cluster of Excellence Frankfurt-Macromolecular Complexes, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany
| | - Elisabeth Fischer
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany.,Cluster of Excellence Frankfurt-Macromolecular Complexes, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany
| | - Lior Shaltiel
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany
| | - Wagner Steuer Costa
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany.,Cluster of Excellence Frankfurt-Macromolecular Complexes, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany
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16
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Ramakrishnan K, Okkema PG. Regulation of C. elegans neuronal differentiation by the ZEB-family factor ZAG-1 and the NK-2 homeodomain factor CEH-28. PLoS One 2014; 9:e113893. [PMID: 25474681 PMCID: PMC4256384 DOI: 10.1371/journal.pone.0113893] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/02/2014] [Indexed: 12/28/2022] Open
Abstract
The C. elegans pharyngeal neuron M4 is a multi-functional cell that acts as a cholinergic motor neuron to stimulate peristaltic pharyngeal muscle contraction and as a neuroendocrine cell secreting neuropeptides and growth factors to affect other cells both inside and outside the pharynx. The conserved transcription factors ZAG-1 and CEH-28 are co-expressed in M4 through most of development, and here we examine how these factors contribute to M4 differentiation. We find ZAG-1 functions upstream of CEH-28 in a branched pathway to activate expression of different sets of M4 differentiation markers. CEH-28 activates expression of the growth factor genes dbl-1 and egl-17, and the neuropeptide genes flp-5 and flp-2, while ZAG-1 activates expression of the serotonin receptor ser-7, as well as expression of ceh-28 and its downstream targets. Other markers of M4 differentiation are expressed normally in both zag-1 and ceh-28 mutants, including the neuropeptide gene flp-21 and the acetylcholine biosynthetic gene unc-17. Unlike ceh-28 mutants, zag-1 mutants completely lack peristaltic muscle contractions resulting from broader defects in M4 differentiation. Despite these defects, neither ZAG-1 nor CEH-28 are terminal selectors of the M4 phenotype, and we suggest they function in a hierarchy to regulate different aspects of M4 differentiation.
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Affiliation(s)
- Kalpana Ramakrishnan
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Peter G. Okkema
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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17
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Hu C, Kearn J, Urwin P, Lilley C, O' Connor V, Holden-Dye L, Morgan H. StyletChip: a microfluidic device for recording host invasion behaviour and feeding of plant parasitic nematodes. LAB ON A CHIP 2014; 14:2447-2455. [PMID: 24839944 DOI: 10.1039/c4lc00292j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Plant parasitic nematodes (PPNs) infest the roots of crops and cause global losses with a severe economic impact on food production. Current chemical control agents are being removed from use due to environmental and toxicity concerns and there is a need for new approaches to crop protection. A key feature of parasitic behaviour for the majority of PPNs is a hollow stomastyle or odontostyle required for interaction with the host plant and feeding. This lance-like microscopic structure, often called a stylet, protrudes from the mouth of the worm and thrusts in a rhythmic manner to stab the host root. Studying stylet activity presents technical challenges and as a consequence the underlying biology is poorly understood. We have addressed this by designing a microfluidic chip which traps the PPN Globodera pallida and permits the recording of an electrophysiological signal concomitant with stylet thrusting. The PDMS chip incorporates a precisely designed aperture to trap the nematode securely around a mid-point of its body. It is fabricated using a novel combination of conventional photolithography and two photon polymerization. The chip incorporates valves for rapid application of test compounds and integral electrodes to facilitate acquisition of electrical signals. We show that stylet thrusting can be induced by controlled application of 5-HT (serotonin) to the worm. Each thrust and retraction produces an electrical waveform that characterises the physiological activity associated with the worm's behaviour. The ability to reproducibly record the stylet activity of PPNs provides a new platform for nematicide screening that specifically focuses on a behaviour that is integral to the parasite host interaction. This is the first report of a microfluidic chip capable of electrophysiological recording from nematodes other than Caenorhabditis elegans. The unique approach is optimised for trapping and recording from smaller worms or worms with distinct anterior body shapes and may be applied to other species of economic or medical importance.
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Affiliation(s)
- Chunxiao Hu
- Faculty of Physical Sciences and Engineering, and Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
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18
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Kearn J, Ludlow E, Dillon J, O'Connor V, Holden-Dye L. Fluensulfone is a nematicide with a mode of action distinct from anticholinesterases and macrocyclic lactones. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2014; 109:44-57. [PMID: 24581383 DOI: 10.1016/j.pestbp.2014.01.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 06/03/2023]
Abstract
Plant parasitic nematodes infest crops and present a threat to food security worldwide. Currently available chemical controls e.g. methyl bromide, organophosphates and carbamates have an unacceptable level of toxicity to non-target organisms and are being withdrawn from use. Fluensulfone is a new nematicide of the fluoroalkenyl thioether group that has significantly reduced environmental impact with low toxicity to non-target insects and mammals. Here, we show that the model genetic organism Caenorhabditis elegans is susceptible to the irreversible nematicidal effects of fluensulfone. Whilst the dose required is higher than that which has nematicidal activity against Meloidogyne spp. the profile of effects on motility, egg-hatching and survival is similar to that reported for plant parasitic nematodes. C. elegans thus provides a tractable experimental paradigm to analyse the effects of fluensulfone on nematode behaviour. We find that fluensulfone has pleiotropic actions and inhibits development, egg-laying, egg-hatching, feeding and locomotion. In the case of feeding and locomotion, an early excitation precedes the gross inhibition. The profile of these effects is notably distinct from other classes of anthelmintic and nematicide: the inhibition of motility caused by fluensulfone is not accompanied by the hypercontraction which is characteristic of organophosphates and carbamates and C. elegans mutants that are resistant to the carbamate aldicarb and the macrocyclic lactone ivermectin retain susceptibility to fluensulfone. These data indicate fluensulfone's mode of action is distinct from currently available nematicides and it therefore presents a promising new chemical entity for crop protection.
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Affiliation(s)
- James Kearn
- Centre for Biological Sciences, University of Southampton, Building 85, University Road, Southampton SO17 1BJ, United Kingdom
| | - Elizabeth Ludlow
- Centre for Biological Sciences, University of Southampton, Building 85, University Road, Southampton SO17 1BJ, United Kingdom
| | - James Dillon
- Centre for Biological Sciences, University of Southampton, Building 85, University Road, Southampton SO17 1BJ, United Kingdom
| | - Vincent O'Connor
- Centre for Biological Sciences, University of Southampton, Building 85, University Road, Southampton SO17 1BJ, United Kingdom
| | - Lindy Holden-Dye
- Centre for Biological Sciences, University of Southampton, Building 85, University Road, Southampton SO17 1BJ, United Kingdom.
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19
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Dillon J, Andrianakis I, Mould R, Ient B, Liu W, James C, O'Connor V, Holden-Dye L. Distinct molecular targets including SLO-1 and gap junctions are engaged across a continuum of ethanol concentrations in Caenorhabditis elegans. FASEB J 2013; 27:4266-78. [PMID: 23882127 DOI: 10.1096/fj.11-189340] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Ethanol (alcohol) interacts with diverse molecular effectors across a range of concentrations in the brain, eliciting intoxication through to sedation. Invertebrate models including the nematode worm Caenorhabditis elegans have been deployed for molecular genetic studies to inform on key components of these alcohol signaling pathways. C. elegans studies have typically employed external dosing with high (>250 mM) ethanol concentrations: A careful analysis of responses to low concentrations is lacking. Using the C. elegans pharyngeal system as a paradigm, we report a previously uncharacterized continuum of cellular and behavioral responses to ethanol from low (10 mM) to high (300 mM) concentrations. The complexity of these responses indicates that the pleiotropic action of ethanol observed in mammalian brain is conserved in this invertebrate model. We investigated two candidate ethanol effectors, the calcium-activated K(+) channel SLO-1 and gap junctions, and show that they contribute to, but are not sole determinants of, the low- and high-concentration effects, respectively. Notably, this study shows cellular and whole organismal behavioral responses to ethanol in C. elegans that directly equate to intoxicating through to supralethal blood alcohol concentrations in humans and provides an important benchmark for interpretation of paradigms that seek to inform on human alcohol use disorders.
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Affiliation(s)
- James Dillon
- 1Current address: Institute of Digital Healthcare, Warwick Manufacturing Group, University of Warwick, Coventry CV4 7AL, UK
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20
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Hu C, Dillon J, Kearn J, Murray C, O’Connor V, Holden-Dye L, Morgan H. NeuroChip: a microfluidic electrophysiological device for genetic and chemical biology screening of Caenorhabditis elegans adult and larvae. PLoS One 2013; 8:e64297. [PMID: 23717588 PMCID: PMC3661448 DOI: 10.1371/journal.pone.0064297] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/11/2013] [Indexed: 11/18/2022] Open
Abstract
Genetic and chemical biology screens of C. elegans have been of enormous benefit in providing fundamental insight into neural function and neuroactive drugs. Recently the exploitation of microfluidic devices has added greater power to this experimental approach providing more discrete and higher throughput phenotypic analysis of neural systems. Here we make a significant addition to this repertoire through the design of a semi-automated microfluidic device, NeuroChip, which has been optimised for selecting worms based on the electrophysiological features of the pharyngeal neural network. We demonstrate this device has the capability to sort mutant from wild-type worms based on high definition extracellular electrophysiological recordings. NeuroChip resolves discrete differences in excitatory, inhibitory and neuromodulatory components of the neural network from individual animals. Worms may be fed into the device consecutively from a reservoir and recovered unharmed. It combines microfluidics with integrated electrode recording for sequential trapping, restraining, recording, releasing and recovering of C. elegans. Thus mutant worms may be selected, recovered and propagated enabling mutagenesis screens based on an electrophysiological phenotype. Drugs may be rapidly applied during the recording thus permitting compound screening. For toxicology, this analysis can provide a precise description of sub-lethal effects on neural function. The chamber has been modified to accommodate L2 larval stages showing applicability for small size nematodes including parasitic species which otherwise are not tractable to this experimental approach. We also combine NeuroChip with optogenetics for targeted interrogation of the function of the neural circuit. NeuroChip thus adds a new tool for exploitation of C. elegans and has applications in neurogenetics, drug discovery and neurotoxicology.
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Affiliation(s)
- Chunxiao Hu
- Hybrid Biodevices Group, Electronics and Computer Science, University of Southampton, Southampton, United Kingdom
| | - James Dillon
- Centre for Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - James Kearn
- Centre for Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Caitriona Murray
- Centre for Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Vincent O’Connor
- Centre for Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Lindy Holden-Dye
- Centre for Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- * E-mail:
| | - Hywel Morgan
- Hybrid Biodevices Group, Electronics and Computer Science, University of Southampton, Southampton, United Kingdom
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21
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Bumbarger DJ, Riebesell M, Rödelsperger C, Sommer RJ. System-wide rewiring underlies behavioral differences in predatory and bacterial-feeding nematodes. Cell 2013; 152:109-19. [PMID: 23332749 DOI: 10.1016/j.cell.2012.12.013] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/26/2012] [Accepted: 12/07/2012] [Indexed: 10/27/2022]
Abstract
The relationship between neural circuit function and patterns of synaptic connectivity is poorly understood, in part due to a lack of comparative data for larger complete systems. We compare system-wide maps of synaptic connectivity generated from serial transmission electron microscopy for the pharyngeal nervous systems of two nematodes with divergent feeding behavior: the microbivore Caenorhabditis elegans and the predatory nematode Pristionchus pacificus. We uncover a massive rewiring in a complex system of identified neurons, all of which are homologous based on neurite anatomy and cell body position. Comparative graph theoretical analysis reveals a striking pattern of neuronal wiring with increased connectional complexity in the anterior pharynx correlating with tooth-like denticles, a morphological feature in the mouth of P. pacificus. We apply focused centrality methods to identify neurons I1 and I2 as candidates for regulating predatory feeding and predict substantial divergence in the function of pharyngeal glands.
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Affiliation(s)
- Daniel J Bumbarger
- Department for Evolutionary Biology, Max-Planck-Institute for Developmental Biology, Spemannstrasse 37, 72076 Tübingen, Germany
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22
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Holden-Dye L, Joyner M, O'Connor V, Walker RJ. Nicotinic acetylcholine receptors: a comparison of the nAChRs of Caenorhabditis elegans and parasitic nematodes. Parasitol Int 2013; 62:606-15. [PMID: 23500392 DOI: 10.1016/j.parint.2013.03.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/28/2013] [Accepted: 03/05/2013] [Indexed: 01/15/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play a key role in the normal physiology of nematodes and provide an established target site for anthelmintics. The free-living nematode, Caenorhabditis elegans, has a large number of nAChR subunit genes in its genome and so provides an experimental model for testing novel anthelmintics which act at these sites. However, many parasitic nematodes lack specific genes present in C. elegans, and so care is required in extrapolating from studies using C. elegans to the situation in other nematodes. In this review the properties of C. elegans nAChRs are reviewed and compared to those of parasitic nematodes. This forms the basis for a discussion of the possible subunit composition of nAChRs from different species of parasitic nematodes. Currently our knowledge on this is largely based on studies using heterologous expression and pharmacological analysis of receptor subunits in Xenopus laevis oocytes. It is concluded that more information is required regarding the subunit composition and pharmacology of endogenous nAChRs in parasitic nematodes.
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Affiliation(s)
- Lindy Holden-Dye
- Centre for Biological Sciences, Life Sciences Building 85, University of Southampton, Southampton SO17 1BJ, UK.
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23
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Hattori Y, Suzuki M, Soh Z, Kobayashi Y, Tsuji T. Modeling of the pharyngeal muscle in Caenorhabditis elegans based on FitzHugh-Nagumo equations. ARTIFICIAL LIFE AND ROBOTICS 2012. [DOI: 10.1007/s10015-012-0064-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Holden-Dye L, Walker RJ. Report on the 12th symposium on invertebrate neurobiology held 31 August-4 September 2011 at the Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany, Hungary. INVERTEBRATE NEUROSCIENCE 2012; 12:69-79. [PMID: 22481213 DOI: 10.1007/s10158-012-0131-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
In August 2011, the 12th international symposium of ISIN was held by Lake Balaton in Tihany, Hungary. This convivial and stimulating meeting provided a forum for discussion of a range of invertebrate organisms in neuroscience research. Here the main topics covered at the meeting are reviewed.
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Affiliation(s)
- Lindy Holden-Dye
- Centre for Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
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Eicosanoid formation by a cytochrome P450 isoform expressed in the pharynx of Caenorhabditis elegans. Biochem J 2011; 435:689-700. [PMID: 21309752 DOI: 10.1042/bj20101942] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Caenorhabditis elegans harbours several CYP (cytochrome P450) genes that are homologous with mammalian CYP isoforms important to the production of physiologically active AA (arachidonic acid) metabolites. We tested the hypothesis that mammals and C. elegans may share similar basic mechanisms of CYP-dependent eicosanoid formation and action. We focused on CYP33E2, an isoform related to the human AA-epoxygenases CYP2C8 and CYP2J2. Co-expression of CYP33E2 with the human NADPH-CYP reductase in insect cells resulted in the reconstitution of an active microsomal mono-oxygenase system that metabolized EPA (eicosapentaenoic acid) and, with lower activity, also AA to specific sets of regioisomeric epoxy- and hydroxy-derivatives. The main products included 17,18-epoxyeicosatetraenoic acid from EPA and 19-hydroxyeicosatetraenoic acid from AA. Using nematode worms carrying a pCYP33E2::GFP reporter construct, we found that CYP33E2 is exclusively expressed in the pharynx, where it is predominantly localized in the marginal cells. RNAi (RNA interference)-mediated CYP33E2 expression silencing as well as treatments with inhibitors of mammalian AA-metabolizing CYP enzymes, significantly reduced the pharyngeal pumping frequency of adult C. elegans. These results demonstrate that EPA and AA are efficient CYP33E2 substrates and suggest that CYP-eicosanoids, influencing in mammals the contractility of cardiomyocytes and vascular smooth muscle cells, may function in C. elegans as regulators of the pharyngeal pumping activity.
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Neurobiology of plant parasitic nematodes. INVERTEBRATE NEUROSCIENCE 2011; 11:9-19. [PMID: 21538093 DOI: 10.1007/s10158-011-0117-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 04/19/2011] [Indexed: 12/31/2022]
Abstract
The regulatory constraints imposed on use of chemical control agents in agriculture are rendering crops increasingly vulnerable to plant parasitic nematodes. Thus, it is important that new control strategies which meet requirements for low toxicity to non-target species, vertebrates and the environment are pursued. This would be greatly facilitated by an improved understanding of the physiology and pharmacology of these nematodes, but to date, these microscopic species of the Phylum Nematoda have attracted little attention in this regard. In this review, the current information available for neurotransmitters and neuromodulator in the plant parasitic nematodes is discussed in the context of the more extensive literature for other species in the phylum, most notably Caenorhabditis elegans and Ascaris suum. Areas of commonality and distinctiveness in terms of neurotransmitter profile and function between these species are highlighted with a view to improving understanding of to what extent, and with what level of confidence, this information may be extrapolated to the plant parasitic nematodes.
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Luedtke S, O'Connor V, Holden-Dye L, Walker RJ. The regulation of feeding and metabolism in response to food deprivation in Caenorhabditis elegans. INVERTEBRATE NEUROSCIENCE 2010; 10:63-76. [PMID: 21120572 DOI: 10.1007/s10158-010-0112-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 11/18/2010] [Indexed: 12/31/2022]
Abstract
This review considers the factors involved in the regulation of feeding and metabolism in response to food deprivation using Caenorhabditis elegans as a model organism. Some of the sensory neurons and interneurons involved in food intake are described, together with an overview of pharyngeal pumping. A number of chemical transmitters control feeding in C. elegans including 5-hydroxytryptamine (5-HT, serotonin), acetylcholine, glutamate, dopamine, octopamine, and tyramine. The roles of these transmitters are modified by neuropeptides, including FMRFamide-like peptides (FLPs), neuropeptide-like protein (NLPs), and insulin-like peptides. The precise effects of many of these neuropeptides have yet to be elucidated but increasingly they are being shown to play a role in feeding and metabolism in C. elegans. The regulation of fat stores is complex and appears to involve the expression of a large number of genes, many with mammalian homologues, suggesting that fat regulatory signalling is conserved across phyla. Finally, a brief comparison is made between C. elegans and mammals where for both, despite their evolutionary distance, classical transmitters and neuropeptides have anorectic or orexigenic properties. Thus, there is a rationale to support the argument that an understanding of the molecular and genetic basis of feeding and fat regulation in C. elegans may contribute to efforts aimed at the identification of targets for the treatment of conditions associated with abnormal metabolism and obesity.
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Affiliation(s)
- Sarah Luedtke
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
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Packham R, Walker RJ, Holden-Dye L. The effect of a selective octopamine antagonist, epinastine, on pharyngeal pumping in Caenorhabditis elegans. INVERTEBRATE NEUROSCIENCE 2010; 10:47-52. [PMID: 20967561 DOI: 10.1007/s10158-010-0107-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Accepted: 10/05/2010] [Indexed: 11/30/2022]
Abstract
This paper investigates the effect of epinastine, a selective octopamine antagonist in invertebrates, in Caenorhabditis elegans. Specifically, its ability to block the inhibitory action of octopamine on C. elegans-isolated pharynx was assayed. Isolated pharynxes were stimulated to pump by the addition of 500 nM 5-hydroxytryptamine (5-HT) (113 ± 2 per 30 s, n = 15). Octopamine inhibited the 5-HT-induced pumping in a concentration-dependent manner (threshold 1-5 μM) with a 61 ± 11% inhibition with 50 μM (n = 5). Epinastine (0.1 μM) antagonized the inhibitory response to octopamine (P < 0.001; n = 15). Tyramine also inhibited pharyngeal pumping induced by 5-HT but was less potent than octopamine. Tyramine, 50 μM to 1 mM, gave a transient inhibition e.g. of 40 ± 5% at 50 μM (n = 5). A higher (10 μM) concentration of epinastine was required to block the tryamine response compared with octopamine. It is concluded that epinastine selectively antagonizes the effect of octopamine on C. elegans pharynx. Further studies are required to test its selectivity for octopamine in other tissues and other nematodes.
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Affiliation(s)
- Rachel Packham
- School of Biological Sciences, University of Southampton, Highfield Campus, Life Sciences Building 85, Southampton, SO17 1BJ, UK
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Pan RK, Chatterjee N, Sinha S. Mesoscopic organization reveals the constraints governing Caenorhabditis elegans nervous system. PLoS One 2010; 5:e9240. [PMID: 20179757 PMCID: PMC2825259 DOI: 10.1371/journal.pone.0009240] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 01/07/2010] [Indexed: 12/23/2022] Open
Abstract
One of the biggest challenges in biology is to understand how activity at the cellular level of neurons, as a result of their mutual interactions, leads to the observed behavior of an organism responding to a variety of environmental stimuli. Investigating the intermediate or mesoscopic level of organization in the nervous system is a vital step towards understanding how the integration of micro-level dynamics results in macro-level functioning. The coordination of many different co-occurring processes at this level underlies the command and control of overall network activity. In this paper, we have considered the somatic nervous system of the nematode Caenorhabditis elegans, for which the entire neuronal connectivity diagram is known. We focus on the organization of the system into modules, i.e., neuronal groups having relatively higher connection density compared to that of the overall network. We show that this mesoscopic feature cannot be explained exclusively in terms of considerations such as, optimizing for resource constraints (viz., total wiring cost) and communication efficiency (i.e., network path length). Even including information about the genetic relatedness of the cells cannot account for the observed modular structure. Comparison with other complex networks designed for efficient transport (of signals or resources) implies that neuronal networks form a distinct class. This suggests that the principal function of the network, viz., processing of sensory information resulting in appropriate motor response, may be playing a vital role in determining the connection topology. Using modular spectral analysis we make explicit the intimate relation between function and structure in the nervous system. This is further brought out by identifying functionally critical neurons purely on the basis of patterns of intra- and inter-modular connections. Our study reveals how the design of the nervous system reflects several constraints, including its key functional role as a processor of information.
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Affiliation(s)
- Raj Kumar Pan
- The Institute of Mathematical Sciences, Chennai, Tamil Nadu, India
| | | | - Sitabhra Sinha
- The Institute of Mathematical Sciences, Chennai, Tamil Nadu, India
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Itzhack R, Louzoun Y. Random distance dependent attachment as a model for neural network generation in the Caenorhabditis elegans. ACTA ACUST UNITED AC 2010; 26:647-52. [PMID: 20081220 DOI: 10.1093/bioinformatics/btq015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
MOTIVATION The topology of the network induced by the neurons connectivity's in the Caenorhabditis elegans differs from most common random networks. The neurons positions of the C.elegans have been previously explained as being optimal to induce the required network wiring. We here propose a complementary explanation that the network wiring is the direct result of a local stochastic synapse formation process. RESULTS We show that a model based on the physical distance between neurons can explain the C.elegans neural network structure, specifically, we demonstrate that a simple model based on a geometrical synapse formation probability and the inhibition of short coherent cycles can explain the properties of the C.elegans' neural network. We suggest this model as an initial framework to discuss neural network generation and as a first step toward the development of models for more advanced creatures. In order to measure the circle frequency in the network, a novel graph-theory circle length measurement algorithm is proposed.
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Affiliation(s)
- Royi Itzhack
- Math Department and Gonda Brain Research Center, Bar Ilan University, Ramat Gan 52900, Israel
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Dillon J, Andrianakis I, Bull K, Glautier S, O'Connor V, Holden-Dye L, James C. AutoEPG: software for the analysis of electrical activity in the microcircuit underpinning feeding behaviour of Caenorhabditis elegans. PLoS One 2009; 4:e8482. [PMID: 20041123 PMCID: PMC2795780 DOI: 10.1371/journal.pone.0008482] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 11/09/2009] [Indexed: 11/19/2022] Open
Abstract
Background The pharyngeal microcircuit of the nematode Caenorhabditis elegans serves as a model for analysing neural network activity and is amenable to electrophysiological recording techniques. One such technique is the electropharyngeogram (EPG) which has provided insight into the genetic basis of feeding behaviour, neurotransmission and muscle excitability. However, the detailed manual analysis of the digital recordings necessary to identify subtle differences in activity that reflect modulatory changes within the underlying network is time consuming and low throughput. To address this we have developed an automated system for the high-throughput and discrete analysis of EPG recordings (AutoEPG). Methodology/Principal Findings AutoEPG employs a tailor made signal processing algorithm that automatically detects different features of the EPG signal including those that report on the relaxation and contraction of the muscle and neuronal activity. Manual verification of the detection algorithm has demonstrated AutoEPG is capable of very high levels of accuracy. We have further validated the software by analysing existing mutant strains with known pharyngeal phenotypes detectable by the EPG. In doing so, we have more precisely defined an evolutionarily conserved role for the calcium-dependent potassium channel, SLO-1, in modulating the rhythmic activity of neural networks. Conclusions/Significance AutoEPG enables the consistent analysis of EPG recordings, significantly increases analysis throughput and allows the robust identification of subtle changes in the electrical activity of the pharyngeal nervous system. It is anticipated that AutoEPG will further add to the experimental tractability of the C. elegans pharynx as a model neural circuit.
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Affiliation(s)
- James Dillon
- School of Biological Sciences, Bassett Crescent East, University of Southampton, Southampton, United Kingdom.
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Mühlfeld S, Schmitt-Wrede HP, Harder A, Wunderlich F. FMRFamide-like neuropeptides as putative ligands of the latrophilin-like HC110-R from Haemonchus contortus. Mol Biochem Parasitol 2009; 164:162-4. [DOI: 10.1016/j.molbiopara.2008.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 12/04/2008] [Accepted: 12/04/2008] [Indexed: 10/21/2022]
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Franks CJ, Murray C, Ogden D, O'Connor V, Holden-Dye L. A comparison of electrically evoked and channel rhodopsin-evoked postsynaptic potentials in the pharyngeal system of Caenorhabditis elegans. INVERTEBRATE NEUROSCIENCE 2009; 9:43-56. [PMID: 19294439 DOI: 10.1007/s10158-009-0088-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Accepted: 03/02/2009] [Indexed: 12/31/2022]
Abstract
Dissecting the function of neural circuits requires the capability to stimulate and record from the component neurones. Optimally, the methods employed should enable precise activation of distinct elements within the circuit and high-fidelity readout of the neuronal response. Here we compare two methods for neural stimulation in the pharyngeal system of Caenorhabditis elegans by evoking postsynaptic potentials (PSPs) either by electrical stimulation or by expression of the channelrhodopsin [ChR2(gf)] in cholinergic neurones of the pharyngeal circuit. Using a dissection that isolates the pharynx and its embedded neural system of 20 neurones permits analysis of the neurotransmitter pathways within this microcircuit. We describe protocols for selective electrically evoked or ChR2-mediated cholinergic synaptic events in this circuit. The latter was achieved by generating strains, punc-17::ChR2(gf);yfp, that express ChR2(gf) in cholinergic neurones. PSPs evoked by both electrical and light stimulation exhibited a rapid time-course and were blocked by cholinergic receptor antagonists and rapidly reversed on cessation of the stimulus. Electrically evoked PSPs were also reduced in a hypomorphic mutant for the synaptic vesicle acetylcholine transporter, unc-17, further indicating they are nicotinic cholinergic PSPs. The pharyngeal nervous system is exquisitely sensitive to both electrical and light activation. For the latter, short light pulses of 200 mus delivered to punc-17::ChR2(gf);yfp are capable of generating full muscle action potentials. We conclude that the application of optogenetic approaches to the C. elegans isolated pharynx preparation opens the way for a precise molecular dissection of synaptic events in the pharyngeal microcircuit by providing a molecular and system level analysis of the synapses that control the feeding behaviour of C. elegans.
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Affiliation(s)
- Christopher J Franks
- School of Biological Sciences, Bassett Crescent East, University of Southampton, Southampton SO16 PX, UK
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Ray P, Schnabel R, Okkema PG. Behavioral and synaptic defects in C. elegans lacking the NK-2 homeobox gene ceh-28. Dev Neurobiol 2008; 68:421-33. [PMID: 18161854 DOI: 10.1002/dneu.20599] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
C. elegans pharyngeal behavior consists of two distinct types of muscle contractions, termed pumping and peristalsis. Pumping ingests and concentrates bacteria in the anterior pharyngeal lumen, and it is occasionally followed by a transient peristaltic contraction that carries ingested bacteria through the posterior pharyngeal isthmus. These behaviors are controlled by a small pharyngeal nervous system consisting of 20 neurons that is almost completely independent of the extra-pharyngeal nervous system. The cholinergic motor neuron M4 controls peristalsis via synapses with the posterior isthmus muscles. Here we show that the NK-2 family homeobox gene ceh-28 is expressed in M4, where it regulates synapse assembly and peristalsis. ceh-28 mutants exhibit frequent and prolonged peristalses, and treatment with agonists or antagonists of muscarinic acetylcholine receptors can phenocopy or suppress ceh-28 mutant defects, respectively. Synapses in ceh-28 mutant M4 cells are irregularly spaced and sized, and they are abnormally located along the full length of the isthmus. We suggest that CEH-28 inhibits synaptogenesis, and that ceh-28 mutant behavioral defects result from excessive or ectopic stimulation of muscarinic acetylcholine receptors in the isthmus muscles.
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Affiliation(s)
- Paramita Ray
- Department of Biological Sciences and Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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SLO, SLO, quick, quick, slow: calcium-activated potassium channels as regulators of Caenorhabditis elegans behaviour and targets for anthelmintics. INVERTEBRATE NEUROSCIENCE 2007; 7:199-208. [PMID: 17962986 DOI: 10.1007/s10158-007-0057-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 10/09/2007] [Indexed: 12/26/2022]
Abstract
Large-conductance calcium and voltage-activated potassium channels, termed SLO-1 (or BK), are pivotal players in the regulation of cell excitability across the animal phyla. Furthermore, emerging evidence indicates that these channels are key mediators of a number of neuroactive drugs, including the most recent new anthelmintic, the cyclo-octadepsipeptide emodepside. Detailed reviews of the structure, function and pharmacology of BK channels have recently been provided (Salkoff et al. in Nat Rev Neurosci 7:921-931, 2006; Ghatta et al. in Pharmacol Ther 110:103-116, 2006) and therefore these aspects will only briefly be covered here. The purpose of this review is to discuss how SLO-1 channels might function as regulators of neural transmission and network activity. In particular, we focus on the role of SLO-1 in the regulation of Caenorhabditis elegans behaviour and highlight the role of this channel as an effector for pleiotropic actions of neuroactive drugs, including emodepside. On the premise that C. elegans is a 'model nematode' with respect to many aspects of neural function, the intention is that this might inform a broader understanding of the role of these channels in the nematodes and their potential as novel anthelmintic targets.
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Balthazart J, Ball GF. Topography in the preoptic region: differential regulation of appetitive and consummatory male sexual behaviors. Front Neuroendocrinol 2007; 28:161-78. [PMID: 17624413 PMCID: PMC2100381 DOI: 10.1016/j.yfrne.2007.05.003] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 05/29/2007] [Accepted: 05/29/2007] [Indexed: 11/29/2022]
Abstract
Several studies have suggested dissociations between neural circuits underlying the expression of appetitive (e.g., courtship behavior) and consummatory components (i.e., copulatory behavior) of vertebrate male sexual behavior. The medial preoptic area (mPOA) clearly controls the expression of male copulation but, according to a number of experiments, is not necessarily implicated in the expression of appetitive sexual behavior. In rats for example, lesions to the mPOA eliminate male-typical copulatory behavior but have more subtle or no obvious effects on measures of sexual motivation. Rats with such lesions still pursue and attempt to mount females. They also acquire and perform learned instrumental responses to gain access to females. However, recent lesions studies and measures of the expression of the immediate early gene c-fos demonstrate that, in quail, sub-regions of the mPOA, in particular of its sexually dimorphic component the medial preoptic nucleus, can be specifically linked with either the expression of appetitive or consummatory sexual behavior. In particular more rostral regions can be linked to appetitive components while more caudal regions are involved in consummatory behavior. This functional sub-region variation is associated with neurochemical and hodological specializations (i.e., differences in chemical phenotype of the cells or in their connectivity), especially those related to the actions of androgens in relation to the activation of male sexual behavior, that are also present in rodents and other species. It could thus reflect general principles about POA organization and function in the vertebrate brain.
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Affiliation(s)
- Jacques Balthazart
- Center for Cellular and Molecular Neurobiology, Research Group in Behavioral Neuroendocrinology, University of Liège, 1 Avenue de 1'Hôpital (Bat. B36), B-4000 Liège 1, Belgium.
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Katz PS. Evolution and development of neural circuits in invertebrates. Curr Opin Neurobiol 2006; 17:59-64. [PMID: 17174546 DOI: 10.1016/j.conb.2006.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Accepted: 12/07/2006] [Indexed: 01/06/2023]
Abstract
Developmental mechanisms can shed light on how evolutionary diversity has arisen. Invertebrate nervous systems offer a wealth of diverse structures and functions from which to relate development to evolution. Individual homologous neurons have been shown to have distinct roles in species with different behaviors. In addition, specific neurons have been lost or gained in some phylogenetic lineages. The ability to address the neural basis of behavior at the cellular level in invertebrates has facilitated discoveries showing that species-specific behavior can arise from differences in synaptic strength, in neuronal structure and in neuromodulation. The mechanisms involved in the development of neural circuits lead to these differences across species.
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Affiliation(s)
- Paul S Katz
- Department of Biology, Georgia State University, PO Box 4010, Atlanta, GA 30302-4010, USA.
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