Shape control in the human red cell

1986 ◽  
Vol 80 (1) ◽  
pp. 281-298
Author(s):  
L. Backman
Keyword(s):  
Phosphatidic Acid ◽  
Shape Control ◽  
Control Mechanism ◽  
Cytoskeletal Proteins ◽  
Phosphoinositide Metabolism ◽  
Red Cell ◽  
Spherical Form ◽  
Protein Dephosphorylation ◽  
Shape Changes ◽  
Bilayer Couple

When the human red cell consumes its ATP, the cell loses its discoid character in favour of a spiculated and eventually a spherical form. This discocyte-echinocyte transformation parallels both degradation of phosphatidylinositol 4,5-bisphosphate and phosphatidic acid but not dephosphorylation of cytoskeletal proteins. Dephosphorylation of both spectrin and band 3 lags behind metabolic crenation. Exogenous vanadate accelerates both shape changes and lipid dephosphorylation in a parallel manner during metabolic depletion. In contrast to its effect on lipids, vanadate reduces the rate of protein dephosphorylation. These observations strongly support a shape control mechanism in the red cell, based on phosphoinositide metabolism and compatible with a bilayer-couple model.

scholarly journals Archaeal cell biology: diverse functions of tubulin-like cytoskeletal proteins at the cell envelope

2018 ◽  
Vol 2 (4) ◽  
pp. 547-559 ◽  
Author(s):  
Yan Liao ◽  
Solenne Ithurbide ◽  
Roshali T. de Silva ◽  
Susanne Erdmann ◽  
Iain G. Duggin
Keyword(s):  
Cell Biology ◽  
Shape Control ◽  
Cell Envelope ◽  
Light And Electron Microscopy ◽  
Halophilic Archaea ◽  
Cytoskeletal Proteins ◽  
Model Organisms ◽  
Full Spectrum ◽  
Peptidoglycan Cell Wall ◽  
Domains Of Life

The tubulin superfamily of cytoskeletal proteins is widespread in all three domains of life — Archaea, Bacteria and Eukarya. Tubulins build the microtubules of the eukaryotic cytoskeleton, whereas members of the homologous FtsZ family construct the division ring in prokaryotes and some eukaryotic organelles. Their functions are relatively poorly understood in archaea, yet these microbes contain a remarkable diversity of tubulin superfamily proteins, including FtsZ for division, a newly described major family called CetZ that is involved in archaeal cell shape control, and several other divergent families of unclear function that are implicated in a variety of cell envelope-remodelling contexts. Archaeal model organisms, particularly halophilic archaea such as Haloferax volcanii, have sufficiently developed genetic tools and we show why their large, flattened cells that are capable of controlled differentiation are also well suited to cell biological investigations by live-cell high-resolution light and electron microscopy. As most archaea only have a glycoprotein lattice S-layer, rather than a peptidoglycan cell wall like bacteria, the activity of the tubulin-like cytoskeletal proteins at the cell envelope is expected to vary significantly, and may involve direct membrane remodelling or directed synthesis or insertion of the S-layer protein subunits. Further studies of archaeal cell biology will provide fresh insight into the evolution of cells and the principles in common to their fundamental activities across the full spectrum of cellular life.

scholarly journals Red cell rheology in stomatocyte-echinocyte transformation: roles of cell geometry and cell shape

Blood ◽  
1986 ◽  
Vol 67 (4) ◽  
pp. 1110-1118 ◽  
Author(s):  
WH Reinhart ◽  
S Chien
Keyword(s):  
Cell Volume ◽  
Surface Area ◽  
Optimum Shape ◽  
Red Cell ◽  
Drug Induced ◽  
Filtration Resistance ◽  
Shear Rates ◽  
Geometric Factors ◽  
Shape Changes

Abstract The influence of the shape of the red blood cell during stomatocyte- echinocyte transformation on its deformability was studied by microsieving through pores with diameters of 2.6, 4.5, and 6.9 micron. A stomatocytic transformation was produced by chlorpromazine (0.02, 0.1, and 0.5 mmol/L) and an echinocytic transformation by sodium salicylate (7.5, 30, and 120 mmol/L). For spherostomatocytes, an increase in filtration resistance through 2.6 and 4.5 micron pores was observed, whereas for spheroechinocytes, a decrease in filtration resistance through 2.6 micron pores was found. Larger pores (6.9 micron) were not sensitive to those shape changes. The changes in deformability can be explained by the fact that the surface area of (sphero)-stomatocytes decreased, whereas that of (sphero)-echinocytes increased; the cell volume remained essentially constant. Echinocytes produced by 24-hour adenosine triphosphate depletion differed from drug- induced echinocytes: they had an increased cell volume at constant surface area and consequently an increased filtration resistance through 2.6- and 4.5-micron filter pores. Shape changes with spicule formation are therefore not a homogeneous entity, and cell geometric factors (eg, surface area and volume) must be assessed with care. The viscosity of red cell suspensions at a hematocrit level of 45% was higher for drug-induced echinocytes than discocytes or stomatocytes at all shear rates tested. We conclude that the normal discocyte represents an optimum shape for the flow in vivo since a stomatocytic transformation could impair the passage through the microcirculation (decrease in cell filterability) and an echinocytic transformation could impair the flow in larger vessels (increase in blood viscosity).

Probing into dimension and shape control mechanism of copper(i) sulfide nanomaterials via solventless thermolysis based on mesogenic thiolate precursors

CrystEngComm ◽  
2018 ◽  
Vol 20 (28) ◽  
pp. 4025-4035 ◽  
Author(s):  
Junfei Duan ◽  
Liang Liu ◽  
Zhongying Wu ◽  
Jianglin Fang ◽  
Dongzhong Chen
Keyword(s):  
Shape Control ◽  
Control Mechanism ◽  
Confined Space ◽  
Lamellar Structures

Well-controlled Cu2S nanomaterials mediated by the confined space of the undulated lamellar structures of mesogenic thiolate precursors.

scholarly journals Equilibrium and kinetic effects of drugs on the shapes of human erythrocytes.

1976 ◽  
Vol 70 (1) ◽  
pp. 247-251 ◽  
Author(s):  
M P Sheetz ◽  
S J Singer
Keyword(s):  
Cell Shape ◽  
Human Erythrocytes ◽  
The Other ◽  
Equilibrium Conditions ◽  
Membrane Perturbation ◽  
Preferential Binding ◽  
Kinetic Effects ◽  
Shape Changes ◽  
Bilayer Couple ◽  
Outer Half

We have previously proposed that if the two half-layers of a membrane are different in their protein and lipid compositions, they may respond differently to some membrane perturbation (the bilayer couple hypothesis). This hypothesis has been applied to explain the changes in shape of human erythrocytes that are produced by a variety of amphipathic compounds. These compounds are presumed to intercalate by their hydrophobic ends into the lipid portions of the membrane; if the compounds are anions, the binding is preferentially to the outer half of the bilayer, if cations, to the inner half. It is proposed that such preferential binding causes an expansion of one half-layer relative to the other, with a corresponding change in cell shape. The predicted sidedness of these shape changes is now demonstrated in experiments with methochlorpromazine and 2,4,6-trinitrophenol. Under appropriate nonequilibrium or equilibrium or equilibrium conditions, both of these compounds are shown to be either crenators or cup-formers of the intact erythrocyte, depending upon which side of the membrane they are concentrated in. These results therefore strongly support the bilayer couple hypothesis.

scholarly journals Phosphoinositide metabolism and the morphology of human erythrocytes.

1984 ◽  
Vol 98 (6) ◽  
pp. 1992-1998 ◽  
Author(s):  
J E Ferrell ◽  
W H Huestis
Keyword(s):  
Phosphatidic Acid ◽  
Shape Change ◽  
Human Erythrocytes ◽  
Phosphoinositide Metabolism ◽  
Nutrient Supplementation ◽  
Related Process

ATP-depleted human erythrocytes lose their smooth discoid shape and adopt a spiny, crenated form. This shape change coincides with the conversion of phosphatidylinositol-4,5-bisphosphate to phosphatidylinositol and phosphatidic acid to diacylglycerol. Both crenation and lipid dephosphorylation are accelerated by iodoacetamide, and both are reversed by nutrient supplementation. The observed changes in lipid populations should shrink the membrane inner monolayer by 0.6%, consistent with estimates of bilayer imbalance in crenated cells. These observations suggest that metabolic crenation arises from a loss of inner monolayer area secondary to the degradation of phosphatidylinositol-4,5-bisphosphate and phosphatidic acid. A related process, crenation after Ca2+ loading, appears to arise from a loss inositides by a different pathway.

scholarly journals Fluorescence quenching of spectrin and other red cell membrane cytoskeletal proteins. Relation to hydrophobic binding sites

1992 ◽  
Vol 282 (1) ◽  
pp. 75-80 ◽  
Author(s):  
E Kahana ◽  
J C Pinder ◽  
K S Smith ◽  
W B Gratzer
Keyword(s):  
Cell Membrane ◽  
Fluorescence Quenching ◽  
Binding Sites ◽  
Cytoskeletal Proteins ◽  
Lipid Phase ◽  
Side Chains ◽  
Red Cell ◽  
Segmental Mobility ◽  
Red Cell Membrane ◽  
Hydrophobic Binding

The intrinsic fluorescence of spectrin is strongly quenched by low concentrations of 2-bromostearate. This results from binding at a series of hydrophobic sites. Analysis of dynamic fluorescence quenching by acrylamide, iodide and caesium ions, separately and in conjunction with 2-bromostearate, leads to the conclusion that most of the tryptophan side-chains are exposed to solvent. The sites at which the fatty-acid-quenched tryptophans are located apparently interact with the lipid bilayer in the cell, as judged by quenching by bromostearate dissolved in the lipid phase. A minor proportion of the side-chains in native spectrin give rise to sharp proton magnetic resonance signals, indicative of segmental mobility; these chain elements contain some tryptophan residues, as revealed by weak downfield signals from the heterocyclic ring protons. These signals are not appreciably perturbed by stearic acid or by phosphatidylserine liposomes, suggesting that the hydrophobic binding sites are not in mobile chain elements. By contrast with a series of globular proteins which, with the exception of serum albumins, show little or no quenching by 2-bromostearate, the peripheral red cell membrane skeletal proteins ankyrin (and its spectrin-binding domain), protein 4.1 and (to a lesser extent) actin show evidence of a high affinity for the hydrophobic ligand and may, like spectrin, interact directly with the bilayer in situ.

scholarly journals On the Spherical Form of the Mammalian Erythrocyte

1936 ◽  
Vol 13 (3) ◽  
pp. 298-308
Author(s):  
ERIC PONDER
Keyword(s):  
Cell Surface ◽  
Rose Bengal ◽  
Shape Change ◽  
Red Cell ◽  
Dye Molecules ◽  
Cover Glass ◽  
Special Shape ◽  
Spherical Form ◽  
Mammalian Erythrocyte ◽  
Shape Component

1. The change in form of the mammalian red cell from that of a biconcave disc to that of a sphere in saline, serum, or plasma to which lecithin has been added is studied in detail. The transformation is reversible, and is unaccompanied by a change in cell volume. Different quantities of lecithin are necessary to bring about the shape change in the cells of different animals. 2. A similar change from disc to sphere is produced by the addition of the dyes of the fluorescein series to red cells in saline. The order of increasing activity is: fluorescein, eosin, erythrosine, and rose bengal. Haematoporphyrin also produces a disc-sphere transformation, and in all these cases the spheres can be turned back into discs by the addition of serum or plasma. The shape change is not accompanied by a volume change, and, in the case of rose bengal, it is apparently brought about when there are scarcely sufficient dye molecules to cover the cell surface. 3. The disc-sphere transformation which occurs between a slide and a closely applied cover-glass is discussed in the light of recent experimental results. The cause of this transformation is still obscure. 4. It is pointed out that in all cases in which the disc-sphere transformation occurs (with the exception of the case in which it occurs between slide and cover-glass), the change in form is ultimately followed by lysis. The component of the cell membrane responsible for the special shape seems to break down earlier, and some times very much earlier, than does the component responsible for the semi permeability, but the breakdown of the former is invariably followed by the break down of the latter. The breakdown in the shape component, however, appears to modify the permeability and electrical properties of the cell surface remarkably little.

Intracellular Cytoskeletal Elements and Cytoskeletons in Bacteria

2007 ◽  
Vol 90 (2-3) ◽  
pp. 73-102 ◽  
Author(s):  
Mohamed H.F. Madkour ◽  
Frank Mayer
Keyword(s):  
Shape Control ◽  
Control Cell ◽  
Elongation Factor ◽  
Cytoskeletal Proteins ◽  
New Drugs ◽  
Cell Functions ◽  
Short Period ◽  
New Thinking ◽  
Control Cell Division ◽  
Cytoskeletal Elements

Within a short period of time after the discovery of bacterial cytoskletons, major progress had been made in areas such as general spatial layout of cytoskeletons, their involvement in a variety of cell functions (shape control, cell division, chromosome segregation, cell motility). This progress was achieved by application of advanced investigation techniques. Homologs of eukaryotic actin, tubulin, and intermediate filaments were found in bacteria; cytoskeletal proteins not closely or not at all related to any of these major cytoskeletal proteins were discovered in a number of bacteria such as Mycoplasmas, Spiroplasmas, Spirochetes, Treponema, Caulobacter. A structural role for bacterial elongation factor Tu was indicated. On the basis of this new thinking, new approaches in biotechnology and new drugs are on the way.

Molecular Features of the Cytoskeletal proteins of the Red Cell Membrane

1982 ◽  
pp. 699-712
Author(s):  
Vincent T. Marchesi ◽  
Jon S. Morrow ◽  
David W. Speicher ◽  
William J. Knowles
Keyword(s):  
Cell Membrane ◽  
Cytoskeletal Proteins ◽  
Red Cell ◽  
Red Cell Membrane ◽  
Molecular Features
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