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Escoubet N, Brette R, Pontani LL, Prevost AM. Interaction of the mechanosensitive microswimmer Paramecium with obstacles. R Soc Open Sci 2023; 10:221645. [PMID: 37234495 PMCID: PMC10206458 DOI: 10.1098/rsos.221645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023]
Abstract
In this work, we report investigations of the swimming behaviour of Paramecium tetraurelia, a unicellular microorganism, in micro-engineered pools that are decorated with thousands of cylindrical pillars. Two types of contact interactions are measured, either passive scattering of Paramecium along the obstacle or avoiding reactions (ARs), characterized by an initial backward swimming upon contact, followed by a reorientation before resuming forward motion. We find that ARs are only mechanically triggered approximately 10% of the time. In addition, we observe that only a third of all ARs triggered by contact are instantaneous while two-thirds are delayed by approximately 150 ms. These measurements are consistent with a simple electrophysiological model of mechanotransduction composed of a strong transient current followed by a persistent one upon prolonged contact. This is in apparent contrast with previous electrophysiological measurements where immobilized cells were stimulated with thin probes, which showed instantaneous behavioural responses and no persistent current. Our findings highlight the importance of ecologically relevant approaches to unravel the motility of mechanosensitive microorganisms in complex environments.
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Affiliation(s)
- Nicolas Escoubet
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Jean Perrin, 4 place Jussieu, Paris 75005, France
| | - Romain Brette
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, Paris 75012, France
| | - Lea-Laetitia Pontani
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Jean Perrin, 4 place Jussieu, Paris 75005, France
| | - Alexis Michel Prevost
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Jean Perrin, 4 place Jussieu, Paris 75005, France
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Elices I, Kulkarni A, Escoubet N, Pontani LL, Prevost AM, Brette R. An electrophysiological and kinematic model of Paramecium, the "swimming neuron". PLoS Comput Biol 2023; 19:e1010899. [PMID: 36758112 PMCID: PMC9946239 DOI: 10.1371/journal.pcbi.1010899] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 02/22/2023] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Paramecium is a large unicellular organism that swims in fresh water using cilia. When stimulated by various means (mechanically, chemically, optically, thermally), it often swims backward then turns and swims forward again in a new direction: this is called the avoiding reaction. This reaction is triggered by a calcium-based action potential. For this reason, several authors have called Paramecium the "swimming neuron". Here we present an empirically constrained model of its action potential based on electrophysiology experiments on live immobilized paramecia, together with simultaneous measurement of ciliary beating using particle image velocimetry. Using these measurements and additional behavioral measurements of free swimming, we extend the electrophysiological model by coupling calcium concentration to kinematic parameters, turning it into a swimming model. In this way, we obtain a model of autonomously behaving Paramecium. Finally, we demonstrate how the modeled organism interacts with an environment, can follow gradients and display collective behavior. This work provides a modeling basis for investigating the physiological basis of autonomous behavior of Paramecium in ecological environments.
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Affiliation(s)
- Irene Elices
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Anirudh Kulkarni
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- Department of Bioengineering and Centre for Neurotechnology, Imperial College London, South Kensington Campus, London, United Kingdom
| | - Nicolas Escoubet
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), Paris
| | - Léa-Laetitia Pontani
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), Paris
| | - Alexis Michel Prevost
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), Paris
| | - Romain Brette
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- * E-mail:
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Thomazo JB, Lauga E, Le Révérend B, Wandersman E, Prevost AM. Collective stiffening of soft hair assemblies. Phys Rev E 2020; 102:010602. [PMID: 32795025 DOI: 10.1103/physreve.102.010602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 06/15/2020] [Indexed: 11/07/2022]
Abstract
Many living systems use assemblies of soft and slender structures whose deflections allow them to mechanically probe their immediate environment. In this work, we study the collective response of artificial soft hair assemblies to a shear flow by imaging their deflections. At all hair densities, the deflection is found to be proportional to the local shear stress with a proportionality factor that decreases with density. The measured collective stiffening of hairs is modeled both with a microscopic elastohydrodynamic model that takes into account long-range hydrodynamic hair-hair interactions and a phenomenological model that treats the hair assemblies as an effective porous medium. While the microscopic model is in reasonable agreement with the experiments at low hair density, the phenomenological model is found to be predictive across the entire density range.
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Affiliation(s)
- Jean-Baptiste Thomazo
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, F-75005 Paris, France.,Nestlé Development Centre Lisieux, rue d'Orival, F-14100 Lisieux, France
| | - Eric Lauga
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom
| | | | - E Wandersman
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, F-75005 Paris, France
| | - A M Prevost
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, F-75005 Paris, France
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Kulkarni A, Elices I, Escoubet N, Pontani LL, Prevost AM, Brette R. A simple device to immobilize protists for electrophysiology and microinjection. J Exp Biol 2020; 223:jeb219253. [PMID: 32409484 DOI: 10.1242/jeb.219253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 05/05/2020] [Indexed: 11/20/2022]
Abstract
We present a simple device to mechanically immobilize motile cells such as ciliates. It can be used in particular for intracellular electrophysiology and microinjection. A transparent filter with holes smaller than the specimen is stretched over an outlet. A flow is induced by either a peristaltic pump or a depressurized tank, mechanically entraining cells to the bottom, where they are immobilized against the filter. The cells start swimming again as soon as the flow is stopped. We demonstrate the device by recording action potentials in Paramecium and injecting a fluorescent dye into the cytosol.
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Affiliation(s)
- Anirudh Kulkarni
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Irene Elices
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Nicolas Escoubet
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France
| | - Léa-Laetitia Pontani
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France
| | - Alexis Michel Prevost
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France
| | - Romain Brette
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
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Golovkova I, Montel L, Wandersman E, Bertrand T, Prevost AM, Pontani LL. Depletion attraction impairs the plasticity of emulsions flowing in a constriction. Soft Matter 2020; 16:3294-3302. [PMID: 32173724 DOI: 10.1039/c9sm02343g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the elasto-plastic behavior of dense attractive emulsions under a mechanical perturbation. The attraction is introduced through non-specific depletion interactions between the droplets and is controlled by changing the concentration of surfactant micelles in the continuous phase. We find that such attractive forces are not sufficient to induce any measurable modification on the scalings between the local packing fraction and the deformation of the droplets. However, when the emulsions are flowed through 2D microfluidic constrictions, we uncover a measurable effect of attraction on their elasto-plastic response. Indeed, we measure higher levels of deformation inside the constriction for attractive droplets. In addition, we show that these measurements correlate with droplet rearrangements that are spatially delayed in the constriction for higher attraction forces.
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Affiliation(s)
- Iaroslava Golovkova
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France.
| | - Lorraine Montel
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France.
| | - Elie Wandersman
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France.
| | - Thibault Bertrand
- Department of Mathematics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
| | - Alexis Michel Prevost
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France.
| | - Lea-Laetitia Pontani
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), F-75005, Paris, France.
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Valet M, Pontani LL, Voituriez R, Wandersman E, Prevost AM. Diffusion through Nanopores in Connected Lipid Bilayer Networks. Phys Rev Lett 2019; 123:088101. [PMID: 31491227 DOI: 10.1103/physrevlett.123.088101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Indexed: 05/16/2023]
Abstract
A biomimetic model of cell-cell communication was developed to probe the passive molecular transport across ion channels inserted in synthetic lipid bilayers formed between contacting droplets arranged in a linear array. Diffusion of a fluorescent probe across the array was measured for different pore concentrations. The diffusion characteristic timescale is found to vary nonlinearly with the pore concentration. Our measurements are successfully modeled by a continuous time random walk description whose waiting time is the first exit time from a droplet through a cluster of pores. The size of the cluster of pores is found to increase with their concentration. Our results provide a direct link between the mesoscopic permeation properties and the microscopic characteristics of the pores, such as their number, size, and spatial arrangement.
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Affiliation(s)
- M Valet
- Laboratoire Jean Perrin CNRS UMR 8237, Sorbonne Université, 4 place Jussieu, 75005 Paris, France
| | - L-L Pontani
- Laboratoire Jean Perrin CNRS UMR 8237, Sorbonne Université, 4 place Jussieu, 75005 Paris, France
| | - R Voituriez
- Laboratoire Jean Perrin CNRS UMR 8237, Sorbonne Université, 4 place Jussieu, 75005 Paris, France
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, Sorbonne Université, 4 place Jussieu, 75005 Paris, France
| | - E Wandersman
- Laboratoire Jean Perrin CNRS UMR 8237, Sorbonne Université, 4 place Jussieu, 75005 Paris, France
| | - A M Prevost
- Laboratoire Jean Perrin CNRS UMR 8237, Sorbonne Université, 4 place Jussieu, 75005 Paris, France
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Yashima S, Romero V, Wandersman E, Frétigny C, Chaudhury MK, Chateauminois A, Prevost AM. Normal contact and friction of rubber with model randomly rough surfaces. Soft Matter 2015; 11:871-881. [PMID: 25514137 DOI: 10.1039/c4sm02346c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on normal contact and friction measurements of model multicontact interfaces formed between smooth surfaces and substrates textured with a statistical distribution of spherical micro-asperities. Contacts are either formed between a rigid textured lens and a smooth rubber, or a flat textured rubber and a smooth rigid lens. Measurements of the real area of contact A versus normal load P are performed by imaging the light transmitted at the microcontacts. For both interfaces, A(P) is found to be sub-linear with a power law behavior. Comparison with two multi-asperity contact models, which extend the Greenwood-Williamson (J. Greenwood and J. Williamson, Proc. Royal Soc. London Ser. A, 295, 300 (1966)) model by taking into account the elastic interaction between asperities at different length scales, is performed, and allows their validation for the first time. We find that long range elastic interactions arising from the curvature of the nominal surfaces are the main source of the non-linearity of A(P). At a shorter range, and except for very low pressures, the pressure dependence of both density and area of microcontacts remains well described by Greenwood-Williamson's model, which neglects any interaction between asperities. In addition, in steady sliding, friction measurements reveal that the mean shear stress at the scale of the asperities is systematically larger than that found for a macroscopic contact between a smooth lens and a rubber. This suggests that frictional stresses measured at macroscopic length scales may not be simply transposed to microscopic multicontact interfaces.
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Affiliation(s)
- S Yashima
- Soft Matter Science and Engineering Laboratory (SIMM), CNRS/UPMC Univ Paris 6, UMR 7615, ESPCI, F-75005 Paris, France
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