Evidence for a transition in the cortical membranes of Paramecium

Paeger, Anne; Fillafer, Christian; Schneider, Mat­thias

doi:10.1016/j.bbamem.2022.184073

Cited by 1 publication

(3 citation statements)

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“…Although the discussion on ion permeability in biomembranes is long-established, starting from the celebrated works by Hodgkin and Huxley, most of these discussions completely ignore the state of the lipid interface itself. Nevertheless, lipid phase transitions have been observed in biomembranes extracted from cells as well as at intact membranes of living cells. , Thus, it may be constructive to explore how embedded proteins modify the membrane phase diagram, hydrogen ion adsorption, and permeability. The proposition to better understand these couplings requires significant experimental and theoretical efforts.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Nevertheless, lipid phase transitions have been observed in biomembranes extracted from cells 32 as well as at intact membranes of living cells. 30,31 Thus, it may be constructive to explore how embedded proteins modify the membrane phase diagram, hydrogen ion adsorption, and permeability. The proposition to better understand these couplings requires significant experimental and theoretical efforts.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, we demonstrate the emergence of excitability near the bifurcation point, which does not require specialized protein components. The merits of this approach lie in its quantitative and testable predictions for excitable and oscillatory responses close to the order–disorder transition in nonliving membranes as well as biomembranes. − …”

Section: Introductionmentioning

confidence: 99%

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Characterizing Oscillatory and Excitability Regimes in a Protein-Free Lipid Membrane

Das

Mussel

2023

Langmuir

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Observations of electric potential oscillations in artificial lipid bilayers near the order−disorder transition indicate the existence of a stable limit cycle and, therefore, the possibility of producing excitable signals close to the bifurcation. We present a theoretical investigation of membrane oscillatory and excitability regimes induced by an increase in ion permeability at the order− disorder transition. The model accounts for the coupled effects of state-dependent permeability, membrane charge density, and hydrogen ion adsorption. A bifurcation diagram shows a transition between fixed-point and limit cycle solutions, enabling both oscillatory and excitability responses at different values of the acid association parameter. Oscillations are identified in terms of the membrane state, electric potential difference, and ion concentration near the membrane. The emerging voltage and time scales agree with measurements. Excitability is demonstrated by applying an external electric current stimulus, and the emerging signals display a threshold response and the appearance of repetitive signals upon using a long-lasting stimulus. The approach highlights the important role of the order−disorder transition, enabling membrane excitability in the absence of specialized proteins.

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