Tension at the Cell Surface

Harvey, E. Newton

doi:10.1007/978-3-7091-5449-6_2

Cited by 12 publications

(8 citation statements)

References 69 publications

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“…The scenario in which two small spherical cells combine into one larger spherical fusion product is known to occur in model systems such as chemically induced protoplast fusion (Senda et al, 1979;Boss, 1987) and in various fusions of spherical nucleated mammalian cells as induced by, for example, laser light pulses (Schierenberg, 1987;Steubing et al, 1991), chemicals (Lucy, 1978), and enveloped viruses (Knutton, 1977;Sarkar et al, 1989). Because surface (interfacial) tension is known to drive the rounding up of cell fragments (Harvey, 1954), the whole cell fusion process appears to take place in a manner that suggests that it is self-completing, passive, and otherwise essentially unremarkable. Understandably, as investigators gradually recognized that membrane fusion was a necessary condition for cell fusion and that membrane fusion could be investigated with molecular or near-molecular level paradigms, interest shifted from primarily descriptive studies (often in connection with genetic experiments) at the cell level (e.g., Harris, 1970;Ringertz and Savage, 1976) to what happens at the membrane level (Poste and Nicolson, 1978;White, 1992;Duzgunes, 1993a, b).…”

Section: Introductionmentioning

confidence: 99%

Surface shape change during fusion of erythrocyte membranes is sensitive to membrane skeleton agents

Rosenberg¹,

Sowers²

1994

Biophysical Journal

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We previously reported that the induction of membrane fusion between pairs of erythrocyte ghosts is accompanied by the formation of a multipore fusion zone that undergoes an area expansion with condition-dependent characteristics. These characteristics allowed us to hypothesize substantial, if not major, involvement of the spectrin-based membrane skeleton in controlling this expansion. It was also found that the fusion zone, which first appears in phase optics as a flat diaphragm, has a lifetime that is also highly condition-dependent. We report here that 2,3-diphosphoglycerate, wheat germ agglutinin, diamide, and N-ethylmaleimide, all known to have binding sites primarily on skeleton components (including spectrin), have condition-dependent effects on specific components of the fusion zone diameter versus time expansion curve and the flat diaphragm lifetime. We also report a pH/ionic strength condition that causes a dramatic stabilization of flat diaphragms in a manner consistent with the known pH/ionic strength dependence of the spectrin calorimetric transition, thus further supporting the hypothesis of spectrin involvement. Our data suggest that the influence of the membrane skeleton on cell fusion is to restrain the rounding up that takes place after membrane fusion and that it may have variable, rather than fixed, mechanical properties. Data show that WGA, a known ligand for sialic acid, and DPG, a known metabolite, influences the flat diaphragm stability and late period expansion rates, raising the possibility that some of these mechanical properties are biologically regulated.

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Section: Introductionmentioning

confidence: 99%

Surface shape change during fusion of erythrocyte membranes is sensitive to membrane skeleton agents

Rosenberg¹,

Sowers²

1994

Biophysical Journal

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“…Thus each cell or droplet has a diameter of 10 µm and the division takes place in several minutes. The membrane tension is taken to be 1·0 dyne/cm; this is consistent with values measured by Harvey [43] and Hochmuth [44].…”

Section: Model Results For Splittingmentioning

confidence: 95%

“…If we use typical values [43,46,18,44], i.e., σ = 1 dyne/cm, µ = 100 poise, R = 5 × 10 −4 cm for a leukocyte and θ e = 10 degrees ≈ 0·2 radian, the value of T * is about 150 seconds which seems a plausible value. Times much smaller than this would have very large cell deformations, as in Figure 3 for example.…”

Section: Energeticsmentioning

confidence: 98%

Surfactant-driven motion and splitting of droplets on a substrate

Schwartz

Roy²,

Eley³

et al. 2004

J Eng Math

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A theoretical and computational model is presented to predict the motion of a small sessile liquid droplet, lying on a solid substrate including surfactant effects. The model, as formulated, consists of coupled partial differential equations in space and time, and several auxilliary relationships. The validity of the long-wave, or 'lubrication' approximation is assumed. It is shown that there are circumstances where surfactant injection or production will cause the droplet to split into two daughter droplets. It is conjectured that the results are relevant to basic mechanisms involved in biological cell division (cytokinesis). It is also demonstrated that motion of a droplet, analogous to the motility of a cell, can be produced by surfactant addition. Computed examples are given here, in both two and three space dimensions. Approximate energy requirements are also calculated for these processes. These are found to be suitably small.

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“…The dielectrophortic force which draws the ghost membranes into contact via the so-called "pearl chain formation" is also known to cause a membrane deformation (Dimitrov et al, 1990) but only measurements can determine if a change in this force before or after the pulse could influence the fusion zone diameter versus time curves. It has been established that membrane fluidity is highly temperature-dependent (Kimmelberg, 1979) over temperature ranges likely to be encountered by a biomembrane but surface tension, expected to be a force in cell rounding (Harvey, 1954) is not expected to be strongly temperature-dependent. Thus, the effect of temperature on diameter versus time measurements is expected to provide a clue from this variable.…”

Section: Further Characterization Of the Diameter Versus Time Kineticsmentioning

confidence: 99%

Distinct mechanical relaxation components in pairs of erythrocyte ghosts undergoing fusion

Sjodin

Sowers

1994

Biophysical Journal

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It was previously reported (Chernomordik and Sowers, 1991) that erythrocyte ghosts which were exposed to a 42 degrees C, 10-min heat treatment would, upon electrofusion, produce over 15-20 s a fusion product with an "open lumen" (i.e., the fusion product became converted to one large sphere), while electrofusion of ghost membranes not so exposed would lead to chains of polyghosts. In phase optics the chains of polyghosts showed a "flat diaphragm" at virtually every ghost-ghost junction (i.e., the ghosts do not appear to be fused even though fluorescent-labeled lipid analogs can laterally diffuse from a labeled ghost to an adjacent unlabeled ghost). In the present study we found that the diameter increase in open lumen- and flat diaphragm-producing fusion processes both had a rapid but short early phase (0-5 s after fusion) which was exponential or nearly so and a slow but long late phase (5-120 s after fusion) which was essentially linear. Heat treatments at 39 or 42 degrees C caused a minor acceleration in only the late phase, while temperatures of 45 or 50 degrees C caused an immediate and dramatic acceleration in the rate of diameter increase (spheres in 1-2 s). Ghost membranes in the presence of glycerol at 20% (v/v) did not form open lumens when exposed to the 42 degrees C (but not the > or = 45 degrees C) heat treatment. This suggested that the heat treatment was denaturing a critical protein. Both of these observations are consistent with the involvement of the spectrin network since it is the only protein in the erythrocyte membrane which is known (Brandts et al., 1977) to have a calorimetric transition over the same temperature range used in our heat treatments. The diameter versus time curves were sensitive to: (i) the residual effects of the fusogenic electric pulse only up to about 1 s after the pulse, (ii) the strength of the dielectrophoretic field after the pulse, but not before the pulse,(iii) the ambient temperature during the measurement.

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Tension at the Cell Surface

Cited by 12 publications

References 69 publications

Surface shape change during fusion of erythrocyte membranes is sensitive to membrane skeleton agents

Surface shape change during fusion of erythrocyte membranes is sensitive to membrane skeleton agents

Surfactant-driven motion and splitting of droplets on a substrate

Distinct mechanical relaxation components in pairs of erythrocyte ghosts undergoing fusion

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