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Paeger A, Fillafer C, Schneider MF. Evidence for a transition in the cortical membranes of Paramecium. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184073. [PMID: 36243036 DOI: 10.1016/j.bbamem.2022.184073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/02/2022] [Accepted: 10/07/2022] [Indexed: 11/06/2022]
Abstract
Ever since the pioneering studies in the 1960s and 70s, the importance of order transitions for cell membrane functions has remained a matter of debate. Recently, it has been proposed that the nonlinear stimulus-response curve of excitable cells, which manifests in all-or-none pulses (action potentials (AP)), is due to a transition in the cell membrane. Indeed, evidence for transitions has accumulated in plant cells and neurons, but studies with other excitable cells are expedient in order to show if this finding is of a general nature. Herein, we investigated intact, motile specimens of the "swimming neuron" Paramecium. The cellular membranes were labelled with the solvatochromic fluorophores LAURDAN or Di-4-ANEPPDHQ. Subsequently, a cell was trapped in a microfluidic channel and investigated by fluorescence spectroscopy. The generalized polarization (GP) of the fluorescence emission from cell cortical membranes (probably plasma and alveolar membranes) was extracted by an edge-finding algorithm. The thermo-optical state diagram, i.e. the dependence of GP on temperature, exhibited clear indications for a reversible transition. This transition had a width of ~10-15 °C and a midpoint that was located ~4 °C below the growth temperature. The state diagrams with LAURDAN and Di-4-ANEPPDHQ had widely identical characteristics. These results suggested that the cortical membranes of Paramecium reside in an order transition regime under physiological growth conditions. Based on these findings, membrane potential fluctuations, spontaneous depolarizing spikes, and thermal excitation of Paramecium was interpreted.
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Affiliation(s)
- Anne Paeger
- Medical and Biological Physics, Department of Physics, Technical University Dortmund, Otto-Hahn-Str. 4, 44227 Dortmund, Germany.
| | - Christian Fillafer
- Medical and Biological Physics, Department of Physics, Technical University Dortmund, Otto-Hahn-Str. 4, 44227 Dortmund, Germany.
| | - Matthias F Schneider
- Medical and Biological Physics, Department of Physics, Technical University Dortmund, Otto-Hahn-Str. 4, 44227 Dortmund, Germany.
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Fabiunke S, Fillafer C, Paeger A, Schneider MF. Optical studies of membrane state during action potential propagation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:69-78. [DOI: 10.1016/j.pbiomolbio.2020.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/05/2020] [Accepted: 11/13/2020] [Indexed: 10/23/2022]
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Fillafer C, Paeger A, Schneider MF. The living state: How cellular excitability is controlled by the thermodynamic state of the membrane. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:57-68. [PMID: 33058943 DOI: 10.1016/j.pbiomolbio.2020.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 10/08/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022]
Abstract
The thermodynamic (TD) properties of biological membranes play a central role for living systems. It has been suggested, for instance, that nonlinear pulses such as action potentials (APs) can only exist if the membrane state is in vicinity of a TD transition. Herein, two membrane properties in living systems - excitability and velocity - are analyzed for a broad spectrum of conditions (temperature (T), 3D-pressure (p) and pH-dependence). Based on experimental data from Characean cells and a review of literature we predict parameter ranges in which a transition of the membrane is located (15-35°C below growth temperature; 1-3pH units below pH7; at ∼800atm) and propose the corresponding phase diagrams. The latter explain: (i) changes of AP velocity with T,p and pH.(ii) The existence and origin of two qualitatively different forms of loss of nonlinear excitability ("nerve block", anesthesia). (iii) The type and quantity of parameter changes that trigger APs. Finally, a quantitative comparison between the TD behavior of 2D-lipid model membranes with living systems is attempted. The typical shifts in transition temperature with pH and p of model membranes agree with values obtained from cell physiological measurements. Taken together, these results suggest that it is not specific molecules that control the excitability of living systems but rather the TD properties of the membrane interface. The approach as proposed herein can be extended to other quantities (membrane potential, calcium concentration, etc.) and makes falsifiable predictions, for example, that a transition exists within the specified parameter ranges in excitable cells.
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Affiliation(s)
- Christian Fillafer
- Medical and Biological Physics, Department of Physics, Technical University Dortmund, Otto-Hahn-Str. 4, 44227, Dortmund, Germany.
| | - Anne Paeger
- Medical and Biological Physics, Department of Physics, Technical University Dortmund, Otto-Hahn-Str. 4, 44227, Dortmund, Germany
| | - Matthias F Schneider
- Medical and Biological Physics, Department of Physics, Technical University Dortmund, Otto-Hahn-Str. 4, 44227, Dortmund, Germany
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Blackmore J, Shrivastava S, Sallet J, Butler CR, Cleveland RO. Ultrasound Neuromodulation: A Review of Results, Mechanisms and Safety. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:1509-1536. [PMID: 31109842 PMCID: PMC6996285 DOI: 10.1016/j.ultrasmedbio.2018.12.015] [Citation(s) in RCA: 231] [Impact Index Per Article: 46.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 12/13/2018] [Accepted: 12/29/2018] [Indexed: 05/03/2023]
Abstract
Ultrasonic neuromodulation is a rapidly growing field, in which low-intensity ultrasound (US) is delivered to nervous system tissue, resulting in transient modulation of neural activity. This review summarizes the findings in the central and peripheral nervous systems from mechanistic studies in cell culture to cognitive behavioral studies in humans. The mechanisms by which US mechanically interacts with neurons and could affect firing are presented. An in-depth safety assessment of current studies shows that parameters for the human studies fall within the safety envelope for US imaging. Challenges associated with accurately targeting US and monitoring the response are described. In conclusion, the literature supports the use of US as a safe, non-invasive brain stimulation modality with improved spatial localization and depth targeting compared with alternative methods. US neurostimulation has the potential to be used both as a scientific instrument to investigate brain function and as a therapeutic modality to modulate brain activity.
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Affiliation(s)
- Joseph Blackmore
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Roosevelt Drive, Oxford, UK
| | - Shamit Shrivastava
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Roosevelt Drive, Oxford, UK
| | - Jerome Sallet
- Wellcome Centre for Integrative Nueroimaging, Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Chris R Butler
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - Robin O Cleveland
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Roosevelt Drive, Oxford, UK.
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Shrivastava S, Schneider MF. Evidence for two-dimensional solitary sound waves in a lipid controlled interface and its implications for biological signalling. J R Soc Interface 2015; 11:20140098. [PMID: 24942845 DOI: 10.1098/rsif.2014.0098] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biological membranes by virtue of their elastic properties should be capable of propagating localized perturbations analogous to sound waves. However, the existence and the possible role of such waves in communication in biology remain unexplored. Here, we report the first observations of two-dimensional solitary elastic pulses in lipid interfaces, excited mechanically and detected by FRET. We demonstrate that the nonlinearity near a maximum in the susceptibility of the lipid monolayer results in solitary pulses that also have a threshold for excitation. These experiments clearly demonstrate that the state of the interface regulates the propagation of pulses both qualitatively and quantitatively. Finally, we elaborate on the striking similarity of the observed phenomenon to nerve pulse propagation and a thermodynamic basis of cell signalling in general.
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Affiliation(s)
- Shamit Shrivastava
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
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Shrivastava S, Kang KH, Schneider MF. Solitary shock waves and adiabatic phase transition in lipid interfaces and nerves. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:012715. [PMID: 25679650 DOI: 10.1103/physreve.91.012715] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Indexed: 06/04/2023]
Abstract
This study shows that the stability of solitary waves excited in a lipid monolayer near a phase transition requires positive curvature of the adiabats, a known necessary condition in shock compression science. It is further shown that the condition results in a threshold for excitation, saturation of the wave's amplitude, and the splitting of the wave at the phase boundaries. Splitting in particular confirms that a hydrated lipid interface can undergo condensation on adiabatic heating, thus showing retrograde behavior. Finally, using the theoretical insights and state dependence of conduction velocity in nerves, the curvature of the adiabatic state diagram is shown to be closely tied to the thermodynamic blockage of nerve pulse propagation.
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Affiliation(s)
- Shamit Shrivastava
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Kevin Heeyong Kang
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Matthias F Schneider
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
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Pruitt NL. Adaptations to temperature in the cellular membranes of crustacea: membrane structure and metabolism. J Therm Biol 1990. [DOI: 10.1016/0306-4565(90)90040-o] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Macdonald AG, Wahle KW, Cossins AR, Behan MK. Temperature, pressure and cholesterol effects on bilayer fluidity; a comparison of pyrene excimer/monomer ratios with the steady-state fluorescence polarization of diphenylhexatriene in liposomes and microsomes. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 938:231-42. [PMID: 3342234 DOI: 10.1016/0005-2736(88)90162-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Pyrene excimer/monomer (E/M) ratios have been compared with the steady-state fluorescence polarization (P) of diphenylhexatriene (DPH) in multilamellar liposomes of dilaurylphosphatidylcholine and rat liver microsomes. The purpose was to use the well-understood properties of DPH to reveal the nature of bilayer fluidity which pyrene manifests as an E/M ratio. Reducing the temperature (from 37 degrees C to 8 degrees C), increasing the hydrostatic pressure (from 0.1 to 70 MPa), and, in liposomes, cholesterol enrichment (up to 0.30 mole fraction) separately decreased the E/M ratios and increased P. The pyrene membrane/buffer partition coefficient was affected by temperature but not by pressure, and in the case of cholesterol enrichment, it was assumed to be unaffected. Plots of P as a function of the E/M ratio showed the two to be closely correlated (r = 0.99 in liposomes and 0.96 in microsomes), independent of the treatment used to reduce fluidity. The apparent activation volume and enthalpy for excimer formation was calculated and compared with published data. Pyrene E/M ratios probably reflect the intermolecular volume (fluidity) of the outer region of the bilayer, which is reduced by a decrease in temperature and an increase in pressure and cholesterol. DPH reports the bilayer interior, which is similarly ordered by the experimental treatments. The regional distinction between the two probes, however, accounts for the divergence of E/M ratios and P, which has been reported in membranes enriched with fluidizing fatty acids.
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Affiliation(s)
- A G Macdonald
- Physiology Department, Marischal College, Aberdeen University, U.K
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Pézolet M, Georgescauld D. Raman spectroscopy of nerve fibers. A study of membrane lipids under steady state conditions. Biophys J 1985; 47:367-72. [PMID: 3978206 PMCID: PMC1435218 DOI: 10.1016/s0006-3495(85)83927-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The molecular structures of different nerve fibers kept in good physiological conditions were studied by laser Raman spectroscopy. For myelinated nerves like the rat sciatic nerve, the Raman spectrum is dominated by bands due to the lipid component of the myelin sheath. The temperature dependence of these bands does not reveal any thermotropic phase transition between 0 and 40 degrees C. There is, however, with temperature, a linear increase in the intermolecular disorder that is accompanied by an increase in the number of gauche bonds of the phospholipid acyl chains. For unmyelinated nerves such as the lobster leg nerve, the C-H stretching region of the Raman spectrum is covered by bands arising from the protein component of the axoplasm. However, for the garfish olfactory nerve that has a high density of excitable membranes, phospholipid bands are observed and can be used as intrinsic structural probes of the excitable membranes. The relative intensity of these bands is also temperature dependent.
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Nandy P, Dutta Choudhury M, Chakrabarti P. Effect of sealing on the incorporation of pyrene in goat erythrocyte ghosts — A fluorescence study. J Biosci 1983. [DOI: 10.1007/bf02716855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Neitchev VZ, Bideaud FA. Glycoprotein-protein interaction examined by kinetic studies of pyrene transfer. Mol Biol Rep 1982; 8:65-9. [PMID: 7078551 DOI: 10.1007/bf00778506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The transfer of pyrene between alpha 1-acid glycoprotein, acethylcholinesterase and sonicated liposomes was used to monitor glycoprotein-protein interaction on the lipid bilayer. When a density solution of glycoprotein or protein labeled with pyrene was mixed with unlabeled suspension of free-phospholipid liposomes, or suspensions containing the complexes of glycoprotein-lipid, protein-lipid, or glycoprotein-protein-lipid, pyrene excimer fluorescence increased with a half-time of approximately 30--50 msec. Since the increase in excimer fluorescence indicates an increase in the microscope concentrations of pyrene, the observed fluorescence change reflects pyrene transfer. The half-times for the increase in excimer fluorescence were determined in the presence of glycoprotein and protein in the liposomes. On the basis of the determined half-times it was concluded that both, glycoprotein and protein are bound on the lipid bilayer. Our data also suggest that the thickness of the lipid bilayer is significantly changed in this case. The observation suggests strongly that the limiting step in the transfer of pyrene is not the dissociation of pyrene, but the uptake of the pyrene monomers by the lipid phase.
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Dong DC, Winnik MA. THE Py SCALE OF SOLVENT POLARITIES. SOLVENT EFFECTS ON THE VIBRONIC FINE STRUCTURE OF PYRENE FLUORESCENCE and EMPIRICAL CORRELATIONS WITH ETand Y VALUES. Photochem Photobiol 1982. [DOI: 10.1111/j.1751-1097.1982.tb03805.x] [Citation(s) in RCA: 372] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Duclohier H, Desmazes JP, Georgescauld D. Electrophysiological modifications induced by the fluorescent probe, pyrene, on Myxicola giant axons. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 597:622-5. [PMID: 6246944 DOI: 10.1016/0005-2736(80)90233-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Current- and voltage-clamp experiments on Myxicola giant axons labelled with pyrene showed decreased Na+ and K+ conductances. The low-frequency membrane capacity and the gating charge transfer were slightly reduced. It may be inferred that pyrene is incorporated in some hydrophobic membrane domains close to the ionic channels.
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