scholarly journals Fusion of phospholipid vesicles with a planar membrane depends on the membrane permeability of the solute used to create the osmotic pressure.

1989 ◽  
Vol 93 (2) ◽  
pp. 201-210 ◽  
Author(s):  
F S Cohen ◽  
W D Niles ◽  
M H Akabas
Keyword(s):  
Osmotic Pressure ◽  
Lipid Bilayer ◽  
Lipid Membrane ◽  
Contact Region ◽  
Companion Paper ◽  
Phospholipid Vesicles ◽  
Osmotic Gradient ◽  
Vesicle Membrane ◽  
Permeable Channel ◽  
Planar Membrane

Phospholipid vesicles fuse with a planar membrane when they are osmotically swollen. Channels in the vesicle membrane are required for swelling to occur when the vesicle-containing compartment is made hyperosmotic by adding a solute (termed an osmoticant). We have studied fusion using two different channels, porin, a highly permeable channel, and nystatin, a much less permeable channel. We report that an osmoticant's ability to support fusion (defined as the magnitude of osmotic gradient necessary to obtain sustained fusion) depends on both its permeability through lipid bilayer as well as its permeability through the channel by which it enters the vesicle interior. With porin as the channel, formamide requires an osmotic gradient about ten times that required with urea, which is approximately 1/40th as permeant as formamide through bare lipid membrane. When nystatin is the channel, however, fusion rates sustained by osmotic gradients of formamide are within a factor of two of those obtained with urea. Vesicles containing a porin-impermeant solute can be induced to swell and fuse with a planar membrane when the impermeant bathing the vesicles is replaced by an isosmotic quantity of a porin-permeant solute. With this method of swelling, formamide is as effective as urea in obtaining fusion. In addition, we report that binding of vesicles to the planar membrane does not make the contact region more permeable to the osmoticant than is bare lipid bilayer. In the companion paper, we quantitatively account for the observation that the ability of a solute to promote fusion depends on its permeability properties and the method of swelling. We show that the intravesicular pressure developed drives fusion.

scholarly journals Fusion of phospholipid vesicles with planar phospholipid bilayer membranes. II. Incorporation of a vesicular membrane marker into the planar membrane.

1980 ◽  
Vol 75 (3) ◽  
pp. 251-270 ◽  
Author(s):  
F S Cohen ◽  
J Zimmerberg ◽  
A Finkelstein
Keyword(s):  
Divalent Cations ◽  
Phospholipid Bilayer ◽  
Phospholipid Vesicles ◽  
Osmotic Gradient ◽  
Bilayer Membranes ◽  
Fusion Procedure ◽  
Vesicular Membrane ◽  
Membrane Contact ◽  
Planar Membrane ◽  
Planar Membranes

Fusion of multilamellar phospholipid vesicles with planar phospholipid bilayer membranes was monitored by the rate of appearance in the planar membrane of an intrinsic membrane protein present in the vesicle membranes. An essential requirement for fusion is an osmotic gradient across the planar membrane, with the cis side (the side containing the vesicles) hyperosmotic to the opposite (trans) side; for substantial fusion rates, divalent cation must also be present on the cis side. Thus, the low fusion rates obtained with 100 mM excess glucose in the cis compartment are enhanced orders of magnitude by the addition of 5-10 mM CaCl2 to the cis compartment. Conversely, the rapid fusion rates induced by 40 mM CaCl2 in the cis compartment are completely suppressed when the osmotic gradient (created by the 40 mM CaCl2) is abolished by addition of an equivalent amount of either CaCl2, NaCl, urea, or glucose to the trans compartment. We propose that fusion occurs by the osmotic swelling of vesicles in contact with the planar membrane, with subsequent rupture of the vesicular and planar membranes in the region of contact. Divalent cations catalyze this process by increasing the frequency and duration of vesicle-planar membrane contact. We argue that essentially this same osmotic mechanism drives biological fusion processes, such as exocytosis. Our fusion procedure provides a general method for incorporating and reconstituting transport proteins into planar phospholipid bilayer membranes.

scholarly journals Hydrostatic pressures developed by osmotically swelling vesicles bound to planar membranes.

1989 ◽  
Vol 93 (2) ◽  
pp. 211-244 ◽  
Author(s):  
W D Niles ◽  
F S Cohen ◽  
A Finkelstein
Keyword(s):  
Contact Region ◽  
Irreversible Thermodynamics ◽  
Open Channels ◽  
Vesicle Membrane ◽  
Osmotic Swelling ◽  
Solute Permeability ◽  
Membrane Permeabilities ◽  
Membrane Contact ◽  
Planar Membrane ◽  
Planar Membranes

When phospholipid vesicles bound to a planar membrane are osmotically swollen, they develop a hydrostatic pressure (delta P) and fuse with the membrane. We have calculated the steady-state delta P, from the equations of irreversible thermodynamics governing water and solute flows, for two general methods of osmotic swelling. In the first method, vesicles are swollen by adding a solute to the vesicle-containing compartment to make it hyperosmotic. delta P is determined by the vesicle membrane's permeabilities to solute and water. If the vesicle membrane is devoid of open channels, then delta P is zero. When the vesicle membrane contains open channels, then delta P peaks at a channel density unique to the solute permeability properties of both the channel and the membrane. The solute enters the vesicle through the channels but leaks out through the region of vesicle-planar membrane contact. delta P is largest for channels having high permeabilities to the solute and for solutes with low membrane permeabilities in the contact region. The model predicts the following order of solutes producing pressures of decreasing magnitude: KCl greater than urea greater than formamide greater than or equal to ethylene glycol. Differences between osmoticants quantitatively depend on the solute permeability of the channel and the density of channels in the vesicle membrane. The order of effectiveness is the same as that experimentally observed for solutes promoting fusion. Therefore, delta P drives fusion. When channels with small permeabilities are used, coupling between solute and water flows within the channel has a significant effect on delta P. In the second method, an impermeant solute bathing the vesicles is isosmotically replaced by a solute which permeates the channels in the vesicle membrane. delta P resulting from this method is much less sensitive to the permeabilities of the channel and membrane to the solute. delta P approaches the theoretical limit set by the concentration of the impermeant solute.

scholarly journals Resonance energy transfer imaging of phospholipid vesicle interaction with a planar phospholipid membrane: undulations and attachment sites in the region of calcium-mediated membrane--membrane adhesion.

1996 ◽  
Vol 107 (3) ◽  
pp. 329-351 ◽  
Author(s):  
W D Niles ◽  
J R Silvius ◽  
F S Cohen
Keyword(s):  
Energy Transfer ◽  
Membrane Fusion ◽  
Contact Region ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Phospholipid Vesicle ◽  
Osmotic Gradient ◽  
Attachment Sites ◽  
Donor And Acceptor ◽  
Planar Membrane

Membrane fusion of a phospholipid vesicle with a planar lipid bilayer is preceded by an initial prefusion stage in which a region of the vesicle membrane adheres to the planar membrane. A resonance energy transfer (RET) imaging microscope, with measured spectral transfer functions and a pair of radiometrically calibrated video cameras, was used to determine both the area of the contact region and the distances between the membranes within this zone. Large vesicles (5-20 microns diam) were labeled with the donor fluorophore coumarin-phosphatidylethanolamine (PE), while the planar membrane was labeled with the acceptor rhodamine-PE. The donor was excited with 390 nm light, and separate images of donor and acceptor emission were formed by the microscope. Distances between the membranes at each location in the image were determined from the RET rate constant (kt) computed from the acceptor:donor emission intensity ratio. In the absence of an osmotic gradient, the vesicles stably adhered to the planar membrane, and the dyes did not migrate between membranes. The region of contact was detected as an area of planar membrane, coincident with the vesicle image, over which rhodamine fluorescence was sensitized by RET. The total area of the contact region depended biphasically on the Ca2+ concentration, but the distance between the bilayers in this zone decreased with increasing [Ca2+]. The changes in area and separation were probably related to divalent cation effects on electrostatic screening and binding to charged membranes. At each [Ca2+], the intermembrane separation varied between 1 and 6 nm within each contact region, indicating membrane undulation prior to adhesion. Intermembrane separation distances < or = 2 nm were localized to discrete sites that formed in an ordered arrangement throughout the contact region. The area of the contact region occupied by these punctate attachment sites was increased at high [Ca2+]. Membrane fusion may be initiated at these sites of closest membrane apposition.

scholarly journals Parameters affecting the fusion of unilamellar phospholipid vesicles with planar bilayer membranes.

1984 ◽  
Vol 98 (3) ◽  
pp. 1054-1062 ◽  
Author(s):  
F S Cohen ◽  
M H Akabas ◽  
J Zimmerberg ◽  
A Finkelstein
Keyword(s):  
Divalent Cation ◽  
Phospholipid Bilayer ◽  
Fusion Process ◽  
Phospholipid Vesicles ◽  
Osmotic Gradient ◽  
Planar Bilayer ◽  
Unilamellar Vesicles ◽  
Bilayer Membranes ◽  
Planar Membrane ◽  
Planar Membranes

It was previously shown (Cohen, F. S., J. Zimmerberg, and A. Finkelstein, 1980, J. Gen. Physiol., 75:251-270) that multilamellar phospholipid vesicles can fuse with decane-containing phospholipid bilayer membranes. An essential requirement for fusion was an osmotic gradient across the planar membrane, with the vesicle-containing (cis) side hyperosmotic with respect to the opposite (trans) side. We now report that unilamellar vesicles will fuse with "hydrocarbon-free" membranes subject to these same osmotic conditions. Thus the same conditions that apply to fusion of multilamellar vesicles with planar bilayer membranes also apply to fusion of unilamellar vesicles with these membranes, and hydrocarbon is not required for the fusion process. If the vesicles and/or planar membrane contain negatively charged lipids, divalent cation (approximately 15 mM Ca++) is required in the cis compartment (in addition to the osmotic gradient across the membrane) to obtain substantial fusion rates. On the other hand, vesicles made from uncharged lipids readily fuse with planar phosphatidylethanolamine planar membranes in the near absence of divalent cation with just an osmotic gradient. Vesicles fuse much more readily with phosphatidylethanolamine-containing than with phosphatidylcholine-containing planar membranes. Although hydrocarbon (decane) is not required in the planar membrane for fusion, it does affect the rate of fusion and causes the fusion process to be dependent on stirring in the cis compartment.

scholarly journals Fusion of phospholipid vesicles with planar phospholipid bilayer membranes. I. Discharge of vesicular contents across the planar membrane.

1980 ◽  
Vol 75 (3) ◽  
pp. 241-250 ◽  
Author(s):  
J Zimmerberg ◽  
F S Cohen ◽  
A Finkelstein
Keyword(s):  
Bilayer Membrane ◽  
Convincing Evidence ◽  
Water Soluble ◽  
Phospholipid Bilayer ◽  
Phospholipid Vesicles ◽  
Biological Phenomenon ◽  
Vesicle Membrane ◽  
Bilayer Membranes ◽  
Phospholipid Bilayer Membrane ◽  
Planar Membrane

Multilamellar phospholipid vesicles are introduced into the cis compartment on one side of a planar phospholipid bilayer membrane. The vesicles contain a water-soluble fluorescent dye trapped in the aqueous phases between the lamellae. If a vesicle containing n lamellae fuses with a planar membrane, an n-1 lamellar vesicle should be discharged into the opposite trans compartment, where it would appear as a discernible fluorescent particle. Thus, fusion events can be assayed by counting the number of fluorescent particles appearing in the trans compartment. In the absence of divalent cation, fusion does not occur, even after vesicles have been in the cis compartment for 40 min. When CaCl2 is introduced into the cis compartment to a concentration of greater than or equal to 20 mM, fusion occurs within the next 20 min; it generally ceases thereafter because of vesicle aggregation in the cis compartment. With approximately 3 x 10(8) vesicles/cm3 in the cis compartment, about 25-50 fusion events occur following CaCl2 addition. The discharge of vesicular contents across the planar membrane is the most convincing evidence of vesicle-membrane fusion and serves as a model for that ubiquitous biological phenomenon--exocytosis.

scholarly journals The Impact of O-Glycosylation on Cyanidin Interaction with POPC Membranes: Structure-Activity Relationship

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2771
Author(s):  
Sylwia Cyboran-Mikołajczyk ◽  
Piotr Jurkiewicz ◽  
Martin Hof ◽  
Halina Kleszczyńska
Keyword(s):  
Biological Activity ◽  
Free Radicals ◽  
Lipid Bilayer ◽  
Lipid Membrane ◽  
Lipid Vesicles ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Beneficial Effects ◽  
Structure Activity ◽  
The Impact

Cyanidin and its O-glycosides have many important physiological functions in plants and beneficial effects on human health. Their biological activity is not entirely clear and depends on the structure of the molecule, in particular, on the number and type of sugar substituents. Therefore, in this study the detailed structure-activity relationship (SARs) of the anthocyanins/anthocyanidins in relation to their interactions with lipid bilayer was determined. On the basis of their antioxidant activity and the changes induced by them in size and Zeta potential of lipid vesicles, and mobility and order of lipid acyl chains, the impact of the number and type of sugar substituents on the biological activity of the compounds was evaluated. The obtained results have shown, that 3-O-glycosylation changes the interaction of cyanidin with lipid bilayer entirely. The 3-O-glycosides containing a monosaccharide induces greater changes in physical properties of the lipid membrane than those containing disaccharides. The presence of additional sugar significantly reduces glycoside interaction with model lipid membrane. Furthermore, O-glycosylation alters the ability of cyanidin to scavenge free radicals. This alteration depends on the type of free radicals and the sensitivity of the method used for their determination.

Selective arrangement of vesicles on artificial lipid membrane by biotin-avidin interaction

2021 ◽  
Author(s):  
Kai Hashino ◽  
Daiya Mombayashi ◽  
Yuto Nakatani ◽  
Azusa Oshima ◽  
Masumi Yamaguchi ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Liquid Crystalline ◽  
Lipid Membrane ◽  
Unsaturated Lipid ◽  
Si Substrates ◽  
Phase Domain ◽  
Unsaturated Lipids ◽  
Lipid Mixtures ◽  
The Difference

Abstract Lipid bilayers suspended over microwells on Si substrates are promising platforms for nanobiodevices that mimic cell membranes. Using the biotin-avidin interaction, we have succeeded in selectively arranging vesicles on the freestanding region of a lipid bilayer. When ternary lipid mixtures of saturated lipid, unsaturated lipid, and cholesterol are used, they separate into liquid-order (Lo) and liquid-crystalline (Lα) domains. A freestanding lipid bilayer prefers the Lα-phase over the Lo-phase because of the difference in their flexibility. In addition, the type of biotinylated lipid determines whether it is localized in the Lα-phase domain or the Lo-phase domain. As a result, the biotinylated unsaturated lipids localized in the Lα-phase domain aggregate in the freestanding lipid bilayer, and vesicles labeled with biotin selectively bind to the freestanding lipid bilayer by the biotin-avidin interaction. This technique helps to introduce biomolecules into the freestanding lipid bilayer of nanobiodevices via vesicles.

Recovery from increased pressure or increased leakiness edema in perfused sheep lungs

1994 ◽  
Vol 77 (1) ◽  
pp. 184-189 ◽  
Author(s):  
M. Fukue ◽  
V. B. Serikov ◽  
E. H. Jerome
Keyword(s):  
Pulmonary Edema ◽  
Osmotic Pressure ◽  
Pulmonary Circulation ◽  
Protein Concentration ◽  
Lymph Flow ◽  
High Protein ◽  
Osmotic Gradient ◽  
Low Protein ◽  
High Protein Concentration ◽  
Interstitial Pulmonary Edema

Two routes by which interstitial pulmonary edema liquid may leave the lung during recovery are reabsorption into the pulmonary circulation and clearance by lung lymphatics. We hypothesized that reabsorption of edema liquid of low protein concentration into the pulmonary circulation would be greater than reabsorption of edema liquid of high protein concentration because of the greater protein osmotic gradient in the former. On the basis of previous studies, lymph flow should contribute minimally to the recovery. In 22 in situ perfused sheep lungs with lymph fistulas, we produced approximately 100 g of osmotic or hydrostatic edema (low protein) or increased leakiness edema by calcium depletion (high protein). To induce reabsorption, we changed the perfusate from low- (1% albumin, osmotic pressure = 4 cmH2O) to high-protein (7% albumin, osmotic pressure = 22 cmH2O) solution in the osmotic group, decreased capillary pressure from 29 +/- 9 to 11 +/- 6 cmH2O in the hydrostatic group, or reversed leakiness by adding CaCl2 to the perfusate in the increased leakiness group. Reabsorption occurred only during recovery from osmotic (40 +/- 22% of filtered liquid) and hydrostatic (15 +/- 11%) edema. Total lung lymph flow during recovery from osmotic, hydrostatic, or increased leakiness edema was 4.9 +/- 3.4, 4.3 +/- 3.4, or 3.5 +/- 1.9 g, respectively. We conclude that during recovery from pulmonary edema interstitial liquid is reabsorbed into the circulation in inverse proportion to its protein concentration. We confirm that only a small fraction of the interstitial edema liquid is cleared by the lymphatics during recovery from any type of edema.

A Finite Element-Based Coarse-Grained Model for Cell–Nanomaterial Interactions by Combining Absolute Nodal Coordinate Formula and Brownian Dynamics

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Teng Ma ◽  
Yuanpeng Liu ◽  
Guochang Lin ◽  
Changguo Wang ◽  
Huifeng Tan
Keyword(s):  
Finite Element ◽  
Brownian Dynamics ◽  
Lipid Membrane ◽  
Contact Region ◽  
Detection Algorithm ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Absolute Nodal Coordinate ◽  
Coarse Grained Model ◽  
Dynamics Simulations

Abstract A fundamental understanding of the interactions between one-dimensional nanomaterials and the cell membrane is of great importance for assessing the hazardous effects of viruses and improving the performance of drug delivery. Here, we propose a finite element-based coarse-grained model to describe the cell entry of nanomaterials based on an absolute nodal coordinate formula and Brownian dynamics. The interactions between nanoparticles and lipid membrane are described by the Lennard–Jones potential, and a contact detection algorithm is used to determine the contact region. Compared with the theoretical and published experimental results, the correctness of the model has been verified. We take two examples to test the robustness of the model: the endocytosis of nanorods grafted with polymer chains and simultaneous entry of multiple nanorods into a lipid membrane. It shows that the model can not only capture the effect of ligand–receptor binding on the penetration but also accurately characterize the cooperative or separate entry of multiple nanorods. This coarse-grained model is computationally highly efficient and will be powerful in combination with molecular dynamics simulations to provide an understanding of cell–nanomaterial interactions.

scholarly journals ProBLM Web Server: Protein and Membrane Placement and Orientation Package

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Taylor Kimmett ◽  
Nicholas Smith ◽  
Shawn Witham ◽  
Marharyta Petukh ◽  
Subhra Sarkar ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Lipid Bilayer ◽  
Lipid Membrane ◽  
3D Structure ◽  
Web Server ◽  
Bilayer Lipid Membrane ◽  
Lipid Bilayer Membranes ◽  
Heavy Atoms ◽  
Membrane Complex ◽  
Position And Orientation

The 3D structures of membrane proteins are typically determined without the presence of a lipid bilayer. For the purpose of studying the role of membranes on the wild type characteristics of the corresponding protein, determining the position and orientation of transmembrane proteins within a membrane environment is highly desirable. Here we report a geometry-based approach to automatically insert a membrane protein with a known 3D structure into pregenerated lipid bilayer membranes with various dimensions and lipid compositions or into a pseudomembrane. The pseudomembrane is built using the Protein Nano-Object Integrator which generates a parallelepiped of user-specified dimensions made up of pseudoatoms. The pseudomembrane allows for modeling the desolvation effects while avoiding plausible errors associated with wrongly assigned protein-lipid contacts. The method is implemented into a web server, the ProBLM server, which is freely available to the biophysical community. The web server allows the user to upload a protein coordinate file and any missing residues or heavy atoms are regenerated. ProBLM then creates a combined protein-membrane complex from the given membrane protein and bilayer lipid membrane or pseudomembrane. The user is given an option to manually refine the model by manipulating the position and orientation of the protein with respect to the membrane.

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