Shape change and physical properties of giant phospholipid vesicles prepared in the presence of an AC electric field

Mathivet, L.; Cribier, Sophie; Devaux, Philippe F.

doi:10.1016/s0006-3495(96)79693-5

Cited by 263 publications

(215 citation statements)

References 30 publications

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“…In the initial response of the GUVs, we have to consider the hidden-excess area (23). Thermal undulation motion of GUV membranes (50,51) and long thin (submicron) tubular protrusions (52,53) can be considered as sources of the hidden-excess membrane area of the GUVs. To prevent the influence of the hidden-excess area, for the experiment using micropipettes (e.g., Figs.…”

Section: Discussionmentioning

confidence: 99%

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

Shibly

Ghatak

Karal

et al. 2016

Biophysical Journal

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Osmotic pressure (P) induces the stretching of plasma membranes of cells or lipid membranes of vesicles, which plays various roles in physiological functions. However, there have been no experimental estimations of the membrane tension of vesicles upon exposure to P. In this report, we estimated experimentally the lateral tension of the membranes of giant unilamellar vesicles (GUVs) when they were transferred into a hypotonic solution. First, we investigated the effect of P on the rate constant, k p , of constant-tension (s ex )-induced rupture of dioleoylphosphatidylcholine (DOPC)-GUVs using the method developed by us recently. We obtained the s ex dependence of k p in GUVs under P and by comparing this result with that in the absence of P, we estimated the tension of the membrane due to P at the swelling equilibrium, s eq osm . Next, we measured the volume change of DOPC-GUVs under small P. The experimentally obtained values of s eq osm and the volume change agreed with their theoretical values within the limits of the experimental errors. Finally, we investigated the characteristics of the P-induced pore formation in GUVs. The s eq osm corresponding to the threshold P at which pore formation is induced is similar to the threshold tension of the s ex -induced rupture. The time course of the radius change of GUVs in the P-induced pore formation depends on the total membrane tension, s t ; for small s t , the radius increased with time to an equilibrium one, which remained constant for a long time until pore formation, but for large s t , the radius increased with time and pore formation occurred before the swelling equilibrium was reached. Based on these results, we discussed the s eq osm and the P-induced pore formation in lipid membranes.

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Section: Discussionmentioning

confidence: 99%

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

Shibly

Ghatak

Karal

et al. 2016

Biophysical Journal

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“…However, this conclusion may not be generalized. Although cholesterol is known to flip rapidly across the lipid bilayer (23, 24), Mathivet et al (19) did not observe retraction of the initial bud formation when egg-LPC was added to egg-PC GUVs containing up to 23 mol % of cholesterol. A possible explanation could be that transbilayer redistribution of cholesterol cannot compensate for area asymmetry due its specific molecular properties, e.g.…”

Section: Resultsmentioning

confidence: 99%

Flippase Activity Detected with Unlabeled Lipids by Shape Changes of Giant Unilamellar Vesicles

Papadopulos

Vehring

López‐Montero

et al. 2007

Journal of Biological Chemistry

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Transbilayer movement of phospholipids in biological membranes is mediated by energy-dependent and energy-independent flippases. Available methods for detection of flippase mediated transversal flip-flop are essentially based on spin-labeled or fluorescent lipid analogues. Here we demonstrate that shape change of giant unilamellar vesicles (GUVs) can be used as a new tool to study the occurrence and time scale of flippase-mediated transbilayer movement of unlabeled phospholipids. Insertion of lipids into the external leaflet created an area difference between the two leaflets that caused the formation of a bud-like structure. Under conditions of negligible flip-flop, the bud was stable. Upon reconstitution of the energy-independent flippase activity of the yeast endoplasmic reticulum into GUVs, the initial bud formation was reversible, and the shapes were recovered. This can be ascribed to a rapid flip-flop leading to relaxation of the monolayer area difference. Theoretical analysis of kinetics of shape changes provides self-consistent determination of the flip-flop rate and further kinetic parameters. Based on that analysis, the half-time of phospholipid flip-flop in the presence of endoplasmic reticulum proteins was found to be on the order of few minutes. In contrast, GUVs reconstituted with influenza virus protein formed stable buds. The results argue for the presence of specific membrane proteins mediating rapid flip-flop.In lipid bilayers the spontaneous movement of major phospholipids, e.g. of phosphatidylcholine (PC), 6 between the two monolayers is slow, with half-times on the order of hours or even days. However, lipid topology of cellular membranes results from a continuous bidirectional movement (flip-flop) of lipids between the two leaflets in which specific membrane proteins, so called flippases, play an essential role (1, 2). Energyindependent flippases allow phospholipids to equilibrate rapidly between the two monolayers, whereas energy-dependent flippases mediate a net transfer of specific phospholipids to one leaflet of the membrane. Candidates for the latter flippase are members of a conserved subfamily of P-type ATPases (2) as well as ATP binding cassette transporters (3).In eukaryotes the cytoplasmic leaflet of the endoplasmic reticulum (ER) membrane is the major site of phospholipid biosynthesis. To ensure stable membrane growth, energy-independent flippases mediate rapid, bidirectional, and rather unspecific phospholipid flip-flop with half-times of minutes or less (4 -7). A similar flippase activity was also found in the bacterial inner membrane, where lipid synthesis occurs likewise at the cytoplasmic leaflet (8).Techniques to determine transbilayer phospholipid movement as well as the activity of flippases have been critically evaluated (9). Spin-labeled and fluorescent lipid analogues have provided much insight into protein-mediated transbilayer dynamics of phospholipids (9). However, the bulky reporter moieties may affect the absolute values of transbilayer lipid movement.An alternati...

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“…8,9 Although the population of the vesicles is heterogeneous regarding their shape and dynamics, characteristical shapes were observed in cardiolipin-POPC vesicles. These shapes appear as manycompartment structures, compartments being separated by soft fluctuating walls (Figure 4).…”

Section: Discussionmentioning

confidence: 99%

Shape and Size of Giant Unilamellar Phospholipid Vesicles Containing Cardiolipin

Tomšiè

Babnik

Lombardo

et al. 2005

J. Chem. Inf. Model.

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The effect of cardiolipin content on the shape and size of giant palmitoyloleylphosphatidylcholine/cardiolipin vesicles was studied. Unilamellar vesicles were prepared in sugar solution by the method of electroformation, from mixtures containing up to 50% weight ratio of cardiolipin. At room temperature the vesicles containing cardiolipin exhibited abrupt changes in the curvature of the vesicle contour indicating regions of phase separation. The deviations from the spherical shape were larger if vesicles were made from mixtures with a higher content of cardiolipin. Numerous vesicles with soft fluctuating walls were observed. The estimated size of the vesicles containing cardiolipin was found to be smaller than the size of pure palmitoyloleylphosphatidylcholine vesicles.

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Shape change and physical properties of giant phospholipid vesicles prepared in the presence of an AC electric field

Cited by 263 publications

References 30 publications

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

Experimental Estimation of Membrane Tension Induced by Osmotic Pressure

Flippase Activity Detected with Unlabeled Lipids by Shape Changes of Giant Unilamellar Vesicles

Shape and Size of Giant Unilamellar Phospholipid Vesicles Containing Cardiolipin

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