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Madirolas G, Al-Asmar A, Gaouar L, Marie-Louise L, Garza-Enríquez A, Rodríguez-Rada V, Khona M, Dal Bello M, Ratzke C, Gore J, Pérez-Escudero A. Caenorhabditis elegans foraging patterns follow a simple rule of thumb. Commun Biol 2023; 6:841. [PMID: 37580527 PMCID: PMC10425387 DOI: 10.1038/s42003-023-05220-3] [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: 08/04/2022] [Accepted: 08/04/2023] [Indexed: 08/16/2023] Open
Abstract
Rules of thumb are behavioral algorithms that approximate optimal behavior while lowering cognitive and sensory costs. One way to reduce these costs is by simplifying the representation of the environment: While the theoretically optimal behavior may depend on many environmental variables, a rule of thumb may use a smaller set of variables that performs reasonably well. Experimental proof of this simplification requires an exhaustive mapping of all relevant combinations of several environmental parameters, which we performed for Caenorhabditis elegans foraging by covering systematically combinations of food density (across 4 orders of magnitude) and food type (across 12 bacterial strains). We found that worms' response is dominated by a single environmental variable: food density measured as number of bacteria per unit surface. They disregard other factors such as biomass content or bacterial strain. We also measured experimentally the impact on fitness of each type of food, determining that the rule is near-optimal and therefore constitutes a rule of thumb that leverages the most informative environmental variable. These results set the stage for further investigations into the underlying genetic and neural mechanisms governing this simplification process, and into its role in the evolution of decision-making strategies.
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Affiliation(s)
- Gabriel Madirolas
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France
| | - Alid Al-Asmar
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France
| | - Lydia Gaouar
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France
| | - Leslie Marie-Louise
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France
| | - Andrea Garza-Enríquez
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France
| | - Valentina Rodríguez-Rada
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France
| | - Mikail Khona
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Martina Dal Bello
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Christoph Ratzke
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Interfaculty Institute for Microbiology and Infection Medicine Tübingen (IMIT), Cluster of Excellence EXC 2124 "Controlling Microbes to Fight Infections" (CMFI), University of Tübingen, Calwerstrasse 7/1, 72076, Tübingen, Germany
| | - Jeff Gore
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alfonso Pérez-Escudero
- Centre de Recherches sur la Cognition Animale (UMR5169), Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, 31062, France.
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Pharmacological Profiling of a Brugia malayi Muscarinic Acetylcholine Receptor as a Putative Antiparasitic Target. Antimicrob Agents Chemother 2023; 67:e0118822. [PMID: 36602350 PMCID: PMC9872666 DOI: 10.1128/aac.01188-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The diversification of anthelmintic targets and mechanisms of action will help ensure the sustainable control of nematode infections in response to the growing threat of drug resistance. G protein-coupled receptors (GPCRs) are established drug targets in human medicine but remain unexploited as anthelmintic substrates despite their important roles in nematode neuromuscular and physiological processes. Bottlenecks in exploring the druggability of parasitic nematode GPCRs include a limited helminth genetic toolkit and difficulties establishing functional heterologous expression. In an effort to address some of these challenges, we profile the function and pharmacology of muscarinic acetylcholine receptors in the human parasite Brugia malayi, an etiological agent of human lymphatic filariasis. While acetylcholine-gated ion channels are intensely studied as targets of existing anthelmintics, comparatively little is known about metabotropic receptor contributions to parasite cholinergic signaling. Using multivariate phenotypic assays in microfilariae and adults, we show that nicotinic and muscarinic compounds disparately affect parasite fitness traits. We identify a putative G protein-linked acetylcholine receptor of B. malayi (Bma-GAR-3) that is highly expressed across intramammalian life stages and adapt spatial RNA in situ hybridization to map receptor transcripts to critical parasite tissues. Tissue-specific expression of Bma-gar-3 in Caenorhabditis elegans (body wall muscle, sensory neurons, and pharynx) enabled receptor deorphanization and pharmacological profiling in a nematode physiological context. Finally, we developed an image-based feeding assay as a reporter of pharyngeal activity to facilitate GPCR screening in parasitized strains. We expect that these receptor characterization approaches and improved knowledge of GARs as putative drug targets will further advance the study of GPCR biology across medically important nematodes.
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Khanijou JK, Yee Z, Raida M, Lee JM, Tay EZE, Gruber J, Walczyk T. Efficiency of Protein Renewal Is Limited by Feed Intake and Not by Protein Lifetime in Aging Caenorhabditis elegans. J Proteome Res 2022; 21:2664-2686. [PMID: 36181456 DOI: 10.1021/acs.jproteome.2c00383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein turnover maintains the proteome's functional integrity. Here, protein turnover efficiency over time in wild-type Caenorhabditis elegans was assessed using inverse [15N]-pulse labeling up to 7 days after the egg-laying phase at 20 °C. Isotopic analysis of some abundant proteins was executed favoring data quality over quantity for mathematical modeling. Surprisingly, isotopic enrichment over time reached an upper limit showing an apparent cessation of protein renewal well before death, with protein fractions inaccessible to turnover ranging from 14 to 83%. For life span modulation, worms were raised at different temperatures after egg laying. Mathematical modeling of isotopic enrichment points either to a slowdown of protein turnover or to an increasing protein fraction resistant to turnover with time. Most notably, the estimated time points of protein turnover cessation from our mathematical model were highly correlated with the observed median life span. Thrashing and pumping rates over time were linearly correlated with isotopic enrichment, therefore linking protein/tracer intake to protein turnover rate and protein life span. If confirmed, life span extension is possible by optimizing protein turnover rate through modulating protein intake in C. elegans and possibly other organisms. While proteome maintenance benefits from a high protein turnover rate, protein turnover is fundamentally energy-intensive, where oxidative stress contributes to damage that it is supposed to repair.
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Affiliation(s)
- Jasmeet Kaur Khanijou
- Department of Chemistry, National University of Singapore (NUS), Singapore 117543, Singapore.,Shared Analytics, Singapore Institute of Food and Biotechnology Innovation (SIFBI), Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore
| | - Zhuangli Yee
- Yale-NUS College, Singapore 138527, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117597, Singapore
| | - Manfred Raida
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117597, Singapore.,Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore
| | - Jin Meng Lee
- Department of Chemistry, National University of Singapore (NUS), Singapore 117543, Singapore
| | - Evan Zhi En Tay
- Department of Chemistry, National University of Singapore (NUS), Singapore 117543, Singapore
| | - Jan Gruber
- Yale-NUS College, Singapore 138527, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore (NUS), Singapore 117597, Singapore
| | - Thomas Walczyk
- Department of Chemistry, National University of Singapore (NUS), Singapore 117543, Singapore
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Bonnard E, Liu J, Zjacic N, Alvarez L, Scholz M. Automatically tracking feeding behavior in populations of foraging C. elegans. eLife 2022; 11:e77252. [PMID: 36083280 PMCID: PMC9462848 DOI: 10.7554/elife.77252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Caenorhabditis elegans feeds on bacteria and other small microorganisms which it ingests using its pharynx, a neuromuscular pump. Currently, measuring feeding behavior requires tracking a single animal, indirectly estimating food intake from population-level metrics, or using restrained animals. To enable large throughput feeding measurements of unrestrained, crawling worms on agarose plates at a single worm resolution, we developed an imaging protocol and a complementary image analysis tool called PharaGlow. We image up to 50 unrestrained crawling worms simultaneously and extract locomotion and feeding behaviors. We demonstrate the tool's robustness and high-throughput capabilities by measuring feeding in different use-case scenarios, such as through development, with genetic and chemical perturbations that result in faster and slower pumping, and in the presence or absence of food. Finally, we demonstrate that our tool is capable of long-term imaging by showing behavioral dynamics of mating animals and worms with different genetic backgrounds. The low-resolution fluorescence microscopes required are readily available in C. elegans laboratories, and in combination with our python-based analysis workflow makes this methodology easily accessible. PharaGlow therefore enables the observation and analysis of the temporal dynamics of feeding and locomotory behaviors with high-throughput and precision in a user-friendly system.
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Affiliation(s)
- Elsa Bonnard
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Jun Liu
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Nicolina Zjacic
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
- Institute of Medical Genetics, University of ZurichZurichSwitzerland
| | - Luis Alvarez
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Monika Scholz
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
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Viri V, Arveiler M, Lehnert T, Gijs MAM. An In Vivo Microfluidic Study of Bacterial Load Dynamics and Absorption in the C. elegans Intestine. MICROMACHINES 2021; 12:832. [PMID: 34357242 PMCID: PMC8304684 DOI: 10.3390/mi12070832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/13/2021] [Accepted: 07/15/2021] [Indexed: 01/19/2023]
Abstract
Caenorhabditiselegans (C. elegans) has gained importance as a model for studying host-microbiota interactions and bacterial infections related to human pathogens. Assessing the fate of ingested bacteria in the worm's intestine is therefore of great interest, in particular with respect to normal bacterial digestion or intestinal colonization by pathogens. Here, we report an in vivo study of bacteria in the gut of C. elegans. We take advantage of a polydimethylsiloxane (PDMS) microfluidic device enabling passive immobilization of adult worms under physiological conditions. Non-pathogenic Escherichia coli (E. coli) bacteria expressing either pH-sensitive or pH-insensitive fluorescence reporters as well as fluorescently marked indigestible microbeads were used for the different assays. Dynamic fluorescence patterns of the bacterial load in the worm gut were conveniently monitored by time-lapse imaging. Cyclic motion of the bacterial load due to peristaltic activity of the gut was observed and biochemical digestion of E. coli was characterized by high-resolution fluorescence imaging of the worm's intestine. We could discriminate between individual intact bacteria and diffuse signals related to disrupted bacteria that can be digested. From the decay of the diffuse fluorescent signal, we determined a digestion time constant of 14 ± 4 s. In order to evaluate the possibility to perform infection assays with our platform, immobilized C. elegans worms were fed pathogenic Mycobacterium marinum (M. marinum) bacteria. We analyzed bacterial fate and accumulation in the gut of N2 worms and mitochondrial stress response in a hsp-6::gfp mutant.
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Affiliation(s)
| | | | | | - Martin A. M. Gijs
- Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; (V.V.); (M.A.); (T.L.)
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Dal Bello M, Pérez-Escudero A, Schroeder FC, Gore J. Inversion of pheromone preference optimizes foraging in C. elegans. eLife 2021; 10:58144. [PMID: 34227470 PMCID: PMC8260229 DOI: 10.7554/elife.58144] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/09/2021] [Indexed: 12/20/2022] Open
Abstract
Foraging animals have to locate food sources that are usually patchily distributed and subject to competition. Deciding when to leave a food patch is challenging and requires the animal to integrate information about food availability with cues signaling the presence of other individuals (e.g., pheromones). To study how social information transmitted via pheromones can aid foraging decisions, we investigated the behavioral responses of the model animal Caenorhabditis elegans to food depletion and pheromone accumulation in food patches. We experimentally show that animals consuming a food patch leave it at different times and that the leaving time affects the animal preference for its pheromones. In particular, worms leaving early are attracted to their pheromones, while worms leaving later are repelled by them. We further demonstrate that the inversion from attraction to repulsion depends on associative learning and, by implementing a simple model, we highlight that it is an adaptive solution to optimize food intake during foraging.
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Affiliation(s)
- Martina Dal Bello
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, United States
| | - Alfonso Pérez-Escudero
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, United States.,Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS; UPS, Toulouse, France
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, New York, United States
| | - Jeff Gore
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, United States
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Backes C, Martinez-Martinez D, Cabreiro F. C. elegans: A biosensor for host-microbe interactions. Lab Anim (NY) 2021; 50:127-135. [PMID: 33649581 DOI: 10.1038/s41684-021-00724-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/27/2021] [Indexed: 01/31/2023]
Abstract
Microbes are an integral part of life on this planet. Microbes and their hosts influence each other in an endless dance that shapes how the meta-organism interacts with its environment. Although great advances have been made in microbiome research over the past 20 years, the mechanisms by which both hosts and their microbes interact with each other and the environment are still not well understood. The nematode Caenorhabditis elegans has been widely used as a model organism to study a remarkable number of human-like processes. Recent evidence shows that the worm is a powerful tool to investigate in fine detail the complexity that exists in microbe-host interactions. By combining the large array of genetic tools available for both organisms together with deep phenotyping approaches, it has been possible to uncover key effectors in the complex relationship between microbes and their hosts. In this perspective, we survey the literature for insightful discoveries in the microbiome field using the worm as a model. We discuss the latest conceptual and technological advances in the field and highlight the strengths that make C. elegans a valuable biosensor tool for the study of microbe-host interactions.
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Affiliation(s)
- Cassandra Backes
- MRC London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK
| | | | - Filipe Cabreiro
- MRC London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK. .,Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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Ding SS, Muhle LS, Brown AEX, Schumacher LJ, Endres RG. Comparison of solitary and collective foraging strategies of Caenorhabditis elegans in patchy food distributions. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190382. [PMID: 32713303 DOI: 10.1098/rstb.2019.0382] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Collective foraging has been shown to benefit organisms in environments where food is patchily distributed, but whether this is true in the case where organisms do not rely on long-range communications to coordinate their collective behaviour has been understudied. To address this question, we use the tractable laboratory model organism Caenorhabditis elegans, where a social strain (npr-1 mutant) and a solitary strain (N2) are available for direct comparison of foraging strategies. We first developed an on-lattice minimal model for comparing collective and solitary foraging strategies, finding that social agents benefit from feeding faster and more efficiently simply owing to group formation. Our laboratory foraging experiments with npr-1 and N2 worm populations, however, show an advantage for solitary N2 in all food distribution environments that we tested. We incorporated additional strain-specific behavioural parameters of npr-1 and N2 worms into our model and computationally identified N2's higher feeding rate to be the key factor underlying its advantage, without which it is possible to recapitulate the advantage of collective foraging in patchy environments. Our work highlights the theoretical advantage of collective foraging owing to group formation alone without long-range interactions and the valuable role of modelling to guide experiments. This article is part of the theme issue 'Multi-scale analysis and modelling of collective migration in biological systems'.
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Affiliation(s)
- Siyu Serena Ding
- Institute of Clinical Sciences, Imperial College London, London, UK.,MRC London Institute of Medical Sciences, London, UK
| | - Leah S Muhle
- Department of Life Sciences, Imperial College London, London, UK.,Department of Physics, Faculty of Science, Eberhard-Karls-Universität, Tübingen, Germany
| | - André E X Brown
- Institute of Clinical Sciences, Imperial College London, London, UK.,MRC London Institute of Medical Sciences, London, UK
| | | | - Robert G Endres
- Department of Life Sciences, Imperial College London, London, UK
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Abstract
This review article highlights our efforts to decode the role of the nervous system in regulating intestinal lipid metabolism in Caenorhabditis elegans. Capitalizing on the prescient and pioneering work of Sydney Brenner and John Sulston in establishing C. elegans as an immensely valuable model system, we have uncovered critical roles for oxygen sensing, population density sensing and food sensing in orchestrating the balance between storing lipids and utilizing them for energy in the intestine, the major organ for lipid metabolism in this model system. Our long-term goal is to reveal the integrative mechanisms and regulatory logic that underlies the complex relationship between genes, environment and internal state in the regulation of energy and whole-body physiology.
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Affiliation(s)
- Supriya Srinivasan
- Department of Neuroscience and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, USA
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