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Kalwa U, Park Y, Kimber MJ, Pandey S. An automated, high-resolution phenotypic assay for adult Brugia malayi and microfilaria. Sci Rep 2024; 14:13176. [PMID: 38849355 PMCID: PMC11161659 DOI: 10.1038/s41598-024-62692-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 05/20/2024] [Indexed: 06/09/2024] Open
Abstract
Brugia malayi are thread-like parasitic worms and one of the etiological agents of Lymphatic filariasis (LF). Existing anthelmintic drugs to treat LF are effective in reducing the larval microfilaria (mf) counts in human bloodstream but are less effective on adult parasites. To test potential drug candidates, we report a multi-parameter phenotypic assay based on tracking the motility of adult B. malayi and mf in vitro. For adult B. malayi, motility is characterized by the centroid velocity, path curvature, angular velocity, eccentricity, extent, and Euler Number. These parameters are evaluated in experiments with three anthelmintic drugs. For B. malayi mf, motility is extracted from the evolving body skeleton to yield positional data and bending angles at 74 key point. We achieved high-fidelity tracking of complex worm postures (self-occlusions, omega turns, body bending, and reversals) while providing a visual representation of pose estimates and behavioral attributes in both space and time scales.
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Affiliation(s)
- Upender Kalwa
- Department of Electrical and Computer Engineering, College of Engineering, Iowa State University, Ames, IA, USA
| | - Yunsoo Park
- Department of Electrical and Computer Engineering, College of Engineering, Iowa State University, Ames, IA, USA
| | - Michael J Kimber
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Santosh Pandey
- Department of Electrical and Computer Engineering, College of Engineering, Iowa State University, Ames, IA, USA.
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2
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Dridi H, Forrester F, Umanskaya A, Xie W, Reiken S, Lacampagne A, Marks A. Role of oxidation of excitation-contraction coupling machinery in age-dependent loss of muscle function in C. elegans. eLife 2022; 11:75529. [PMID: 35506650 PMCID: PMC9113742 DOI: 10.7554/elife.75529] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Age-dependent loss of body wall muscle function and impaired locomotion occur within 2 weeks in C. elegans; however, the underlying mechanism has not been fully elucidated. In humans, age-dependent loss of muscle function occurs at about 80 years of age and has been linked to dysfunction of ryanodine receptor (RyR)/intracellular calcium (Ca2+) release channels on the sarcoplasmic reticulum (SR). Mammalian skeletal muscle RyR1 channels undergo age-related remodeling due to oxidative overload, leading to loss of the stabilizing subunit calstabin1 (FKBP12) from the channel macromolecular complex. This destabilizes the closed state of the channel resulting in intracellular Ca2+ leak, reduced muscle function, and impaired exercise capacity. We now show that the C. elegans RyR homolog, UNC-68, exhibits a remarkable degree of evolutionary conservation with mammalian RyR channels and similar age-dependent dysfunction. Like RyR1 in mammals UNC-68 encodes a protein that comprises a macromolecular complex which includes the calstabin1 homolog FKB-2 and is immunoreactive with antibodies raised against the RyR1 complex. Further, as in aged mammals, UNC-68 is oxidized and depleted of FKB-2 in an age-dependent manner, resulting in 'leaky' channels, depleted SR Ca2+ stores, reduced body wall muscle Ca2+ transients, and age-dependent muscle weakness. FKB-2 (ok3007)-deficient worms exhibit reduced exercise capacity. Pharmacologically induced oxidization of UNC-68 and depletion of FKB-2 from the channel independently caused reduced body wall muscle Ca2+ transients. Preventing FKB-2 depletion from the UNC-68 macromolecular complex using the Rycal drug S107 improved muscle Ca2+ transients and function. Taken together, these data suggest that UNC-68 oxidation plays a role in age-dependent loss of muscle function. Remarkably, this age-dependent loss of muscle function induced by oxidative overload, which takes ~2 years in mice and ~80 years in humans, occurs in less than 2-3 weeks in C. elegans, suggesting that reduced antioxidant capacity may contribute to the differences in life span amongst species.
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Affiliation(s)
- Haikel Dridi
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Frances Forrester
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Alisa Umanskaya
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Wenjun Xie
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Steven Reiken
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Alain Lacampagne
- U1046, Montpellier University, INSERM, CNRS, Montpellier, France
| | - Andrew Marks
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
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Widaad A, Zulkipli IN, Petalcorin MIR. Anthelmintic Effect of Leucaena leucocephala Extract and Its Active Compound, Mimosine, on Vital Behavioral Activities in Caenorhabditis elegans. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27061875. [PMID: 35335240 PMCID: PMC8950933 DOI: 10.3390/molecules27061875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/22/2022] [Accepted: 03/07/2022] [Indexed: 12/03/2022]
Abstract
Helminth infections continue to be a neglected global threat in tropical regions, and there have been growing cases of anthelmintic resistance reported towards the existing anthelmintic drugs. Thus, the search for a novel anthelmintic agent has been increasing, especially those derived from plants. Leucaena leucocephala (LL) is a leguminous plant that is known to have several pharmacological activities, including anthelmintic activity. It is widely known to contain a toxic compound called mimosine, which we believed could be a potential lead candidate that could exert a potent anthelmintic effect. Hence, this study aimed to validate the presence of mimosine in LL extract and to investigate the anthelmintic effect of LL extract and mimosine on head thrashing, egg-laying, and pharyngeal pumping activities using the animal model Caenorhabditis elegans (C. elegans). Mimosine content in LL extract was confirmed through an HPLC analysis of spiking LL extract with different mimosine concentrations, whereby an increasing trend in peak heights was observed at a retention time of 0.9 min. LL extract and mimosine caused a significant dose-dependent increase in the percentage of worm mortality, which produced LC50s of 73 mg/mL and 6.39 mg/mL, respectively. Exposure of C. elegans to different concentrations of LL extract and mimosine significantly decreased the head thrashing, egg-laying, and mean pump amplitude of pharyngeal pumping activity. We speculated that these behavioral changes are due to the inhibitory effect of LL extract and mimosine on an L-type calcium channel called EGL-19. Our findings provide evidential support for the potential of LL extract and its active compound, mimosine, as novel anthelmintic candidates. However, the underlying mechanism of the anthelmintic action has yet to be elucidated.
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Deane G. Consciousness in active inference: Deep self-models, other minds, and the challenge of psychedelic-induced ego-dissolution. Neurosci Conscious 2021; 2021:niab024. [PMID: 34484808 PMCID: PMC8408766 DOI: 10.1093/nc/niab024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 11/16/2022] Open
Abstract
Predictive processing approaches to brain function are increasingly delivering promise for illuminating the computational underpinnings of a wide range of phenomenological states. It remains unclear, however, whether predictive processing is equipped to accommodate a theory of consciousness itself. Furthermore, objectors have argued that without specification of the core computational mechanisms of consciousness, predictive processing is unable to inform the attribution of consciousness to other non-human (biological and artificial) systems. In this paper, I argue that an account of consciousness in the predictive brain is within reach via recent accounts of phenomenal self-modelling in the active inference framework. The central claim here is that phenomenal consciousness is underpinned by 'subjective valuation'-a deep inference about the precision or 'predictability' of the self-evidencing ('fitness-promoting') outcomes of action. Based on this account, I argue that this approach can critically inform the distribution of experience in other systems, paying particular attention to the complex sensory attenuation mechanisms associated with deep self-models. I then consider an objection to the account: several recent papers argue that theories of consciousness that invoke self-consciousness as constitutive or necessary for consciousness are undermined by states (or traits) of 'selflessness'; in particular the 'totally selfless' states of ego-dissolution occasioned by psychedelic drugs. Drawing on existing work that accounts for psychedelic-induced ego-dissolution in the active inference framework, I argue that these states do not threaten to undermine an active inference theory of consciousness. Instead, these accounts corroborate the view that subjective valuation is the constitutive facet of experience, and they highlight the potential of psychedelic research to inform consciousness science, computational psychiatry and computational phenomenology.
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Affiliation(s)
- George Deane
- School of Philosophy, Psychology and Language Sciences, The University of Edinburgh, 3 Charles Street, Edinburgh EH8 9AD, UK
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5
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Bennett MS. Five Breakthroughs: A First Approximation of Brain Evolution From Early Bilaterians to Humans. Front Neuroanat 2021; 15:693346. [PMID: 34489649 PMCID: PMC8418099 DOI: 10.3389/fnana.2021.693346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 07/13/2021] [Indexed: 11/13/2022] Open
Abstract
Retracing the evolutionary steps by which human brains evolved can offer insights into the underlying mechanisms of human brain function as well as the phylogenetic origin of various features of human behavior. To this end, this article presents a model for interpreting the physical and behavioral modifications throughout major milestones in human brain evolution. This model introduces the concept of a "breakthrough" as a useful tool for interpreting suites of brain modifications and the various adaptive behaviors these modifications enabled. This offers a unique view into the ordered steps by which human brains evolved and suggests several unique hypotheses on the mechanisms of human brain function.
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Bennett MS. What Behavioral Abilities Emerged at Key Milestones in Human Brain Evolution? 13 Hypotheses on the 600-Million-Year Phylogenetic History of Human Intelligence. Front Psychol 2021; 12:685853. [PMID: 34393912 PMCID: PMC8358274 DOI: 10.3389/fpsyg.2021.685853] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/16/2021] [Indexed: 01/24/2023] Open
Abstract
This paper presents 13 hypotheses regarding the specific behavioral abilities that emerged at key milestones during the 600-million-year phylogenetic history from early bilaterians to extant humans. The behavioral, intellectual, and cognitive faculties of humans are complex and varied: we have abilities as diverse as map-based navigation, theory of mind, counterfactual learning, episodic memory, and language. But these faculties, which emerge from the complex human brain, are likely to have evolved from simpler prototypes in the simpler brains of our ancestors. Understanding the order in which behavioral abilities evolved can shed light on how and why our brains evolved. To propose these hypotheses, I review the available data from comparative psychology and evolutionary neuroscience.
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Assessing motor-related phenotypes of Caenorhabditis elegans with the wide field-of-view nematode tracking platform. Nat Protoc 2020; 15:2071-2106. [PMID: 32433626 DOI: 10.1038/s41596-020-0321-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/16/2020] [Indexed: 01/23/2023]
Abstract
Caenorhabditis elegans is a valuable model organism in biomedical research that has led to major discoveries in the fields of neurodegeneration, cancer and aging. Because movement phenotypes are commonly used and represent strong indicators of C. elegans fitness, there is an increasing need to replace manual assessments of worm motility with automated measurements to increase throughput and minimize observer biases. Here, we provide a protocol for the implementation of the improved wide field-of-view nematode tracking platform (WF-NTP), which enables the simultaneous analysis of hundreds of worms with respect to multiple behavioral parameters. The protocol takes only a few hours to complete, excluding the time spent culturing C. elegans, and includes (i) experimental design and preparation of samples, (ii) data recording, (iii) software management with appropriate parameter choices and (iv) post-experimental data analysis. We compare the WF-NTP with other existing worm trackers, including those having high spatial resolution. The main benefits of WF-NTP relate to the high number of worms that can be assessed at the same time on a whole-plate basis and the number of phenotypes that can be screened for simultaneously.
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8
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Kudumala S, Sossi S, Carvelli L. Swimming Induced Paralysis to Assess Dopamine Signaling in Caenorhabditis elegans. J Vis Exp 2019. [PMID: 31009010 DOI: 10.3791/59243] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The swimming assay described in this protocol is a valid tool to identify proteins regulating the dopaminergic synapses. Similar to mammals, dopamine (DA) controls several functions in C. elegans including learning and motor activity. Conditions that stimulate DA release (e.g., amphetamine (AMPH) treatments) or that prevent DA clearance (e.g., animals lacking the DA transporter (dat-1) which are incapable of reaccumulating DA into the neurons) generate an excess of extracellular DA ultimately resulting in inhibited locomotion. This behavior is particularly evident when animals swim in water. In fact, while wild-type animals continue to swim for an extended period, dat-1 null mutants and wild-type treated with AMPH or inhibitors of the DA transporter sink to the bottom of the well and do not move. This behavior is termed "Swimming Induced Paralysis" (SWIP). Although the SWIP assay is well established, a detailed description of the method is lacking. Here, we describe a step-by-step guide to perform SWIP. To perform the assay, late larval stage-4 animals are placed in a glass spot plate containing control sucrose solution with or without AMPH. Animals are scored for their swimming behavior either manually by visualization under a stereoscope or automatically by recording with a camera mounted on the stereoscope. Videos are then analyzed using a tracking software, which yields a visual representation of thrashing frequency and paralysis in the form of heat maps. Both the manual and automated systems guarantee an easily quantifiable readout of the animals' swimming ability and thus facilitate screening for animals bearing mutations within the dopaminergic system or for auxiliary genes. In addition, SWIP can be used to elucidate the mechanism of action of drugs of abuse such as AMPH.
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Affiliation(s)
- Sirisha Kudumala
- Harriet Wilkes Honors College, Florida Atlantic University, John D MacArthur Campus
| | - Serena Sossi
- Integrative Biology and Neuroscience program, College of Science, Florida Atlantic University
| | - Lucia Carvelli
- Harriet Wilkes Honors College, Florida Atlantic University, John D MacArthur Campus; Brain Institute, Florida Atlantic University; Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University;
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The Foodborne Strain Lactobacillus fermentum MBC2 Triggers pept-1-Dependent Pro-Longevity Effects in Caenorhabditis elegans. Microorganisms 2019; 7:microorganisms7020045. [PMID: 30736484 PMCID: PMC6406943 DOI: 10.3390/microorganisms7020045] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/21/2019] [Accepted: 02/07/2019] [Indexed: 12/16/2022] Open
Abstract
Lactic acid bacteria (LAB) are involved in several food fermentations and many of them provide strain-specific health benefits. Herein, the probiotic potential of the foodborne strain Lactobacillus fermentum MBC2 was investigated through in vitro and in vivo approaches. Caenorhabditis elegans was used as an in vivo model to analyze pro-longevity and anti-aging effects. L. fermentum MBC2 showed a high gut colonization capability compared to E. coli OP50 (OP50) or L.rhamnosus GG (LGG). Moreover, analysis of pumping rate, lipofuscin accumulation, and body bending showed anti-aging effects in L. fermentum MBC2-fed worms. Studies on PEPT-1 mutants demonstrated that pept-1 gene was involved in the anti-aging processes mediated by this bacterial strain through DAF-16, whereas the oxidative stress protection was PEPT-1 independent. Moreover, analysis of acid tolerance, bile tolerance, and antibiotic susceptibility were evaluated. L. fermentum MBC2 exerted beneficial effects on nematode lifespan, influencing energy metabolism and oxidative stress resistance, resulted in being tolerant to acidic pH and able to adhere to Caco-2 cells. Overall, these findings provide new insight for application of this strain in the food industry as a newly isolated functional starter. Furthermore, these results will also shed light on C. elegans molecular players involved in host-microbe interactions.
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Gottschling DC, Döring F. Is C. elegans a suitable model for nutritional science? GENES AND NUTRITION 2019; 14:1. [PMID: 30651890 PMCID: PMC6327375 DOI: 10.1186/s12263-018-0625-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 12/05/2018] [Indexed: 02/14/2023]
Abstract
The suitability of C. elegans as a model for the question of nutritional science is a controversial topic. The discussion makes clear that C. elegans is its own best model for revealing, via genetic approaches, biological principles of nutritional behavior, and the biochemical function of vitamins. In this case, the model has a discovery function. Worm research serves also in the identification of nutrition-dependent pathways that could be used for novel approaches in human nutritional studies. This heuristic function of the model guides the applied nutrition research in an innovative direction. Since the nutrition and metabolism for the worm and man differ from each other somewhat strongly, results of nutritional studies in C. elegans are not directly applicable to human nutrition. In general, the C. elegans model is primarily appropriate for explaining the causality of general species’ nutritional phenotypes. Experience tells us that the analysis of drastic nutritional phenotypes in C. elegans has the potential to enrich the canon of knowledge of nutritional science.
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Affiliation(s)
- Dieter-Christian Gottschling
- Department of Human Nutrition and Food Research, University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany
| | - Frank Döring
- Department of Human Nutrition and Food Research, University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany
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11
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Atakan HB, Cornaglia M, Mouchiroud L, Auwerx J, Gijs MAM. Automated high-content phenotyping from the first larval stage till the onset of adulthood of the nematode Caenorhabditis elegans. LAB ON A CHIP 2018; 19:120-135. [PMID: 30484462 PMCID: PMC6309680 DOI: 10.1039/c8lc00863a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The nematode Caenorhabditis elegans is increasingly used as a model for human biology. However, in vivo culturing platforms for C. elegans allowing high-content phenotyping during their life cycle in an automated fashion are lacking so far. Here, a multiplexed microfluidic platform for the rapid high-content phenotyping of populations of C. elegans down to single animal resolution is presented. Nematodes are (i) reversibly and regularly confined during their life inside tapered channels for imaging fluorescence signal expression and to measure their growth parameters, and (ii) allowed to freely move in microfluidic chambers, during which the swimming behavior was video-recorded. The obtained data sets are analyzed in an automated way and 19 phenotypic parameters are extracted. Our platform is employed for studying the effect of bacteria dilution, a form of dietary restriction (DR) in nematodes, on a worm model of Huntington's disease and demonstrates the influence of DR on disease regression.
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Affiliation(s)
- Huseyin Baris Atakan
- Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
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Palyanov A, Khayrulin S, Larson SD. Three-dimensional simulation of the Caenorhabditis elegans body and muscle cells in liquid and gel environments for behavioural analysis. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170376. [PMID: 30201840 PMCID: PMC6158221 DOI: 10.1098/rstb.2017.0376] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2018] [Indexed: 02/06/2023] Open
Abstract
To better understand how a nervous system controls the movements of an organism, we have created a three-dimensional computational biomechanical model of the Caenorhabditis elegans body based on real anatomical structure. The body model is created with a particle system-based simulation engine known as Sibernetic, which implements the smoothed particle-hydrodynamics algorithm. The model includes an elastic body-wall cuticle subject to hydrostatic pressure. This cuticle is then driven by body-wall muscle cells that contract and relax, whose positions and shape are mapped from C. elegans anatomy, and determined from light microscopy and electron micrograph data. We show that by using different muscle activation patterns, this model is capable of producing C. elegans-like behaviours, including crawling and swimming locomotion in environments with different viscosities, while fitting multiple additional known biomechanical properties of the animal. This article is part of a discussion meeting issue 'Connectome to behaviour: modelling C. elegans at cellular resolution'.
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Affiliation(s)
- Andrey Palyanov
- Laboratory of Complex Systems Simulation, A.P. Ershov Institute of Informatics Systems, Acad. Lavrentiev ave. 6, 630090 Novosibirsk, Russia
- Laboratory of Structural Bioinformatics and Molecular Modeling, Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia
- OpenWorm Foundation, ℅ Software Freedom Law Center, 1995 Broadway, 17th Fl., New York, NY 10023, USA
| | - Sergey Khayrulin
- Laboratory of Complex Systems Simulation, A.P. Ershov Institute of Informatics Systems, Acad. Lavrentiev ave. 6, 630090 Novosibirsk, Russia
- Laboratory of Structural Bioinformatics and Molecular Modeling, Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia
- OpenWorm Foundation, ℅ Software Freedom Law Center, 1995 Broadway, 17th Fl., New York, NY 10023, USA
| | - Stephen D Larson
- OpenWorm Foundation, ℅ Software Freedom Law Center, 1995 Broadway, 17th Fl., New York, NY 10023, USA
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Locomotion Behavior Is Affected by the Gα S Pathway and the Two-Pore-Domain K + Channel TWK-7 Interacting in GABAergic Motor Neurons in Caenorhabditis elegans. Genetics 2017; 206:283-297. [PMID: 28341653 DOI: 10.1534/genetics.116.195669] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 03/19/2017] [Indexed: 01/03/2023] Open
Abstract
Adjusting the efficiency of movement in response to environmental cues is an essential integrative characteristic of adaptive locomotion behavior across species. However, the modulatory molecules and the pathways involved are largely unknown. Recently, we demonstrated that in Caenorhabditis elegans, a loss-of-function of the two-pore-domain potassium (K2P) channel TWK-7 causes a fast, coordinated, and persistent forward crawling behavior in which five central aspects of stimulated locomotion-velocity, direction, wave parameters, duration, and straightness-are affected. Here, we isolated the reduction-of-function allele cau1 of the C. elegans gene kin-2 in a forward genetic screen and showed that it phenocopies the locomotor activity and locomotion behavior of twk-7(null) animals. Kin-2 encodes the negative regulatory subunit of protein kinase A (KIN-1/PKA). Consistently, we found that other gain-of-function mutants of the GαS-KIN-1/PKA pathway resemble kin-2(cau1) and twk-7(null) in locomotion phenotype. Using the powerful genetics of the C. elegans system in combination with cell type-specific approaches and detailed locomotion analyses, we identified TWK-7 as a putative downstream target of the GαS-KIN-1/PKA pathway at the level of the γ-aminobutyric acid (GABA)ergic D-type motor neurons. Due to this epistatic interaction, we suggest that KIN-1/PKA and TWK-7 may share a common pathway that is probably involved in the modulation of both locomotor activity and locomotion behavior during forward crawling.
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14
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Partridge FA, Murphy EA, Willis NJ, Bataille CJR, Forman R, Heyer-Chauhan N, Marinič B, Sowood DJC, Wynne GM, Else KJ, Russell AJ, Sattelle DB. Dihydrobenz[e][1,4]oxazepin-2(3H)-ones, a new anthelmintic chemotype immobilising whipworm and reducing infectivity in vivo. PLoS Negl Trop Dis 2017; 11:e0005359. [PMID: 28182663 PMCID: PMC5321434 DOI: 10.1371/journal.pntd.0005359] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 02/22/2017] [Accepted: 01/26/2017] [Indexed: 01/07/2023] Open
Abstract
Trichuris trichiura is a human parasitic whipworm infecting around 500 million people globally, damaging the physical growth and educational performance of those infected. Current drug treatment options are limited and lack efficacy against the worm, preventing an eradication programme. It is therefore important to develop new treatments for trichuriasis. Using Trichuris muris, an established model for T. trichiura, we screened a library of 480 novel drug-like small molecules for compounds causing paralysis of the ex vivo adult parasite. We identified a class of dihydrobenz[e][1,4]oxazepin-2(3H)-one compounds with anthelmintic activity against T. muris. Further screening of structurally related compounds and resynthesis of the most potent molecules led to the identification of 20 active dihydrobenzoxazepinones, a class of molecule not previously implicated in nematode control. The most active immobilise adult T. muris with EC50 values around 25–50μM, comparable to the existing anthelmintic levamisole. The best compounds from this chemotype show low cytotoxicity against murine gut epithelial cells, demonstrating selectivity for the parasite. Developing a novel oral pharmaceutical treatment for a neglected disease and deploying it via mass drug administration is challenging. Interestingly, the dihydrobenzoxazepinone OX02983 reduces the ability of embryonated T. muris eggs to establish infection in the mouse host in vivo. Complementing the potential development of dihydrobenzoxazepinones as an oral anthelmintic, this supports an alternative strategy of developing a therapeutic that acts in the environment, perhaps via a spray, to interrupt the parasite lifecycle. Together these results show that the dihydrobenzoxazepinones are a new class of anthelmintic, active against both egg and adult stages of Trichuris parasites. They demonstrate encouraging selectivity for the parasite, and importantly show considerable scope for further optimisation to improve potency and pharmacokinetic properties with the aim of developing a clinical agent. Trichuris trichiura is a human parasitic whipworm infecting around 500 million people globally and having major consequences on the physical growth and educational performance of those infected. Current drug treatment options are limited and lack efficacy against the worm. Critically, they lack the effectiveness that would allow for a practical program for eradication of this parasite. It is therefore important to develop new treatments for trichuriasis. We screened for molecules that could paralyse the adult of a closely related mouse parasite, and identified a class of compounds, the dihydrobenzoxazepinones, not previously implicated as anthelmintics. Importantly, our compounds are active against the parasite but show only low toxicity against mouse cells, demonstrating selectivity for the parasite. Dihydrobenzoxazepinones could be developed as potential pharmaceutical treatments for trichuriasis. Since developing and deploying new drugs for neglected diseases by mass administration is challenging, we also explored whether the compounds could potentially be used to interrupt the Trichuris lifecycle by acting on eggs. Our dihydrobenzoxazepinone compounds reduced the ability of T. muris eggs to establish infection in their mouse host. This supports an environmental spray strategy for the control of Trichuris targeting their eggs in environmental hotspots such as latrines.
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Affiliation(s)
- Frederick A. Partridge
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, London, United Kingdom
| | - Emma A. Murphy
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Nicky J. Willis
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
| | - Carole J. R. Bataille
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
| | - Ruth Forman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Narinder Heyer-Chauhan
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, London, United Kingdom
| | - Bruno Marinič
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
| | - Daniel J. C. Sowood
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
| | - Graham M. Wynne
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
| | - Kathryn J. Else
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- * E-mail: (KJE); (AJR); (DBS)
| | - Angela J. Russell
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
- * E-mail: (KJE); (AJR); (DBS)
| | - David B. Sattelle
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, London, United Kingdom
- * E-mail: (KJE); (AJR); (DBS)
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Complex Locomotion Behavior Changes Are Induced in Caenorhabditis elegans by the Lack of the Regulatory Leak K+ Channel TWK-7. Genetics 2016; 204:683-701. [PMID: 27535928 DOI: 10.1534/genetics.116.188896] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 08/06/2016] [Indexed: 11/18/2022] Open
Abstract
The change of locomotion activity in response to external cues is a considerable achievement of animals and is required for escape responses, foraging, and other complex behaviors. Little is known about the molecular regulators of such an adaptive locomotion. The conserved eukaryotic two-pore domain potassium (K2P) channels have been recognized as regulatory K+ channels that modify the membrane potential of cells, thereby affecting, e.g., rhythmic muscle activity. By using the Caenorhabditis elegans system combined with cell-type-specific approaches and locomotion in-depth analyses, here, we found that the loss of K2P channel TWK-7 increases the locomotor activity of worms during swimming and crawling in a coordinated mode. Moreover, loss of TWK-7 function results in a hyperactive state that (although less pronounced) resembles the fast, persistent, and directed forward locomotion behavior of stimulated C. elegans TWK-7 is expressed in several head neurons as well as in cholinergic excitatory and GABAergic inhibitory motor neurons. Remarkably, the abundance of TWK-7 in excitatory B-type and inhibitory D-type motor neurons affected five central aspects of adaptive locomotion behavior: velocity/frequency, wavelength/amplitude, direction, duration, and straightness. Hence, we suggest that TWK-7 activity might represent a means to modulate a complex locomotion behavior at the level of certain types of motor neurons.
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Abstract
How, why, and when consciousness evolved remain hotly debated topics. Addressing these issues requires considering the distribution of consciousness across the animal phylogenetic tree. Here we propose that at least one invertebrate clade, the insects, has a capacity for the most basic aspect of consciousness: subjective experience. In vertebrates the capacity for subjective experience is supported by integrated structures in the midbrain that create a neural simulation of the state of the mobile animal in space. This integrated and egocentric representation of the world from the animal's perspective is sufficient for subjective experience. Structures in the insect brain perform analogous functions. Therefore, we argue the insect brain also supports a capacity for subjective experience. In both vertebrates and insects this form of behavioral control system evolved as an efficient solution to basic problems of sensory reafference and true navigation. The brain structures that support subjective experience in vertebrates and insects are very different from each other, but in both cases they are basal to each clade. Hence we propose the origins of subjective experience can be traced to the Cambrian.
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