Electrophoresis, Zeta potential and Surface Charges of Barley Mesophyll Protoplasts

Obi, Ichiro; Ichikawa, Yoshiaki; Kakutani, Tadaaki; Senda, Mitsugi

doi:10.1093/oxfordjournals.pcp.a077706

Cited by 37 publications

(16 citation statements)

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“…Theoretical models predict, and measurements confirm, that the cell-surface potential becomes less negative as the cation concentration of the external medium increases; the effectiveness of the cations increases with increasing charge (5,6,18,21). This occurs because of the higher chargescreening effectiveness of more highly charged ions and because of their greater tendency to bind to surface ligands.…”

Section: Discussionmentioning

confidence: 87%

“…Because of the binding of H+ with carboxylate, phosphate, and amino groups, charge reversal of the plasma membrane surface can occur as the pH there drops below 4 (22). Divalent and polyvalent cations can also bind, and the latter can cause charge reversals at the membrane surface (1,21). Charge screening occurs because coulombic attractions concentrate cations around the cell-surface negative charges.…”

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confidence: 99%

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Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Kinraide¹,

Ryan²,

Kochian³

1992

Plant Physiol.

269

161

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The rhizotoxicities of Al3" and of La3" to wheat (Triticum aestivum L.) were similarly ameliorated by cations in the following order of effectiveness: H -C3 > C2 > C1'. Among tested cations of a given charge, ameliorative effectiveness was similar except that Ca2' was slightly more effective than other divalent cations and H' was much more effective than other monovalent cations. H' rhizotoxicity was also ameliorated by cations in the order C3' > C2 > C1". These results suggest a role for cell-surface electrical potential in the rhizotoxicity of Al3", La3, H', and other toxic cations: negatively charged cell surfaces of the root accumulate the toxic cations, and amelioration is effected by treatments that reduce the negativity of the cell-surface electrical potential by charge screening or cation binding. Membrane whose toxicity has not been established. It may be impossible to differentiate formally the two hypotheses for H+ amelioration of Al toxicity or to establish the rhizotoxicity of all of the Al species (12), but in this article we shall argue that Al" is toxic and that Al3" toxicity, specifically, is ameliorated by H+ and other cations. The argument will rest upon new data that support the hypothesis that the negatively charged cell surfaces in the root accumulate A13+ and other toxic cations, and that amelioration is effected by treatments that reduce the negativity of the cellsurface electrical potential.Negative charges, located in the cell wall and on the plasma membrane, are carried on the carboxylate groups of cell-wall pectins, the residues of acidic amino acids in membrane proteins, and the phosphate groups of membrane phospholipids (16,19,23). The charges on the cell surface create electrical potential gradients that interact with the distribution of ions (5,18,19). Salts in the bathing medium reduce the negative surface potential in two ways: by cation binding and by charge screening. Because of the binding of H+ with carboxylate, phosphate, and amino groups, charge reversal of the plasma membrane surface can occur as the pH there drops below 4 (22). Divalent and polyvalent cations can also bind, and the latter can cause charge reversals at the membrane surface (1, 21). Charge screening occurs because coulombic attractions concentrate cations around the cell-surface negative charges. The effectiveness of the cations in charge screening increases with cation valence according to basic electrostatic models (5,18,19).Amelioration of Al toxicity by H+ and other cations can be interpreted as evidence of the influence of cell surface charge on Al toxicity, but another line of evidence also suggests the same conclusion. Several reports indicate that within closely related taxa, higher varietal sensitivity to Al corresponds to higher varietal cation exchange capacity of whole roots (8, 27, and

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Section: Discussionmentioning

confidence: 87%

mentioning

confidence: 99%

Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Kinraide¹,

Ryan²,

Kochian³

1992

Plant Physiol.

269

161

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“…to achieve agreement, other instances of agreement in that table are independent. Measurements made by Obi et al (1989a) are presented in Table 11. Their protoplasts appear to be less negatively charged.…”

Section: Output Of the Standard Model Compared To Published Resultsmentioning

confidence: 99%

Use of a Gouy-Chapman-Stern Model for Membrane-Surface Electrical Potential to Interpret Some Features of Mineral Rhizotoxicity

Kinraide

1994

Plant Physiol.

104

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a11 distances from the membrane surface. This article presents a consideration of this probably false assumption and the possibilities of a revision of the Grahame equation.The Stem modification of the theory considers ion binding at the membrane surface (Nir et al., 1978;Lau et al., 1981). ms b i n h g the surface charge density to be variable and dependent on the concentration and identities of the various ions. Use of the Gouy-Chapman-Stem model requires the detennination Or assumption Of binding mechaIlisms and the Of binding constants for each ion and each QPe of membrane-binding site.artide Presents a consideration of the suitability of a generalized set of parameters, whose values were selected after evaluation of the literature and without reference to the present data.Finally, data are presented to evaluate the suitability of a A consideration of mineral toxicity to roots only in terms of ion adivities in the rooting medium can be misleading. A CouyChapman-Stern model, by which relative ion activities at cellmembrane surfaces may be estimated, has been applied to problems of mineral rhizotoxicity, including the toxicity of AI3+, La3+, H+, Na+, and SeO, ' -, to wheat (Jriticum aesfivum 1.) roots. l h e Couy-Chapman portion of the model is expressed in the Crahame equation, which relates the charge density ((I) and eledrical potentia1 (4) at the surface of a membrane to the concentrations of ions in a contading bulk solution. l h e Stern modification of thetheory takes into account changes in u caused by ion binding at the membrane surface. Severa1 theoretical problems with the model and its use are considered, including the f a d that previous authors have usually related the physiological effeds of an ion at a membrane surface to the computed concentration (Cio) of the unbound ion rather than its computed adivity (aio). This pradice implies the false assumption that Cio is proportional to aio. It is demonstrated here that aio, computed from externa1 adivities (ai,) by a Nernst equation [a,,, = ai,exp(-ZiFEo/RT), where Zi is the charge on the ion, F is the Faraday constant, R is the gas constant, and T is the temperature], correlates well with ion toxicity and that Ci o sometimes correlates poorly. These conclusions also apply to issues of mineral nutrition.generahed Gouy-Chapman-Stem mode1 to interpret Some features of mineral rh~otoficity. THEORY Chemical Adivity of lonsChemical activity is the thermodynamic property of solutes that determines equilibrium position in chemical reactions (Lindsay, 1979;Nobel, 1991). The activity of solute i (ai) is equal to the concentration (Ci) times an activity coefficient (ri). In ordinary solutions, r i is a function of the charge on solution and may be computed by the vi^^ extension of the Debye-Hückel equation ( h d s a y , 1979). ~~t i v i t y is aiso a d e t e h n a n t in the eqfibrium partitioning of a ion bemeen mo phases (0 and differing in electrical potential, a c c o r~n g to the Nemst equation (Nobel, 1991),ne physiological effects of ions have sometim...

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“…Multivalent inorganic ions are known to reduce net negative charge on the surface of cells as well as on the proteins themselves (Obi et al, 1989;Besteman et al, 2004). While Co 2ϩ , La 3ϩ , and Gd 3ϩ have been used to inhibit or reverse directed migration and growth, their use has not been interpreted as being linked to alteration of surface charge but rather to blockage of plasma membrane Ca 2ϩ channels (Cooper and Schliwa, 1986;McCaig, 1989;Huang et al, 2009) (more below).…”

Section: Redistribution Of Cell-surface Receptorsmentioning

confidence: 99%

Extracellular Electrical Fields Direct Wound Healing and Regeneration

Messerli

Graham²

2011

The Biological Bulletin

129

108

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Abstract. Endogenous DC electric fields (EFs) are important, fundamental components of development, regeneration, and wound healing. The fields are the result of polarized ion transport and current flow through electrically conductive pathways. Nullification of endogenous EFs with pharmacological agents or applied EFs of opposite polarity disturbs the aforementioned processes, while enhancement increases the rate of wound closure and the extent of regeneration. EFs are applied to humans in the clinic, to provide an overwhelming signal for the enhancement of healing of chronic wounds. Although clinical trials, spanning a course of decades, have shown that applied EFs enhance healing of chronic wounds, the mechanisms by which cells sense and respond to these weak cues remains unknown. EFs are thought to influence many different processes in vivo. However, under more rigorously controlled conditions in vitro, applied EFs induce cellular polarity and direct migration and outgrowth. Here we review the generation of endogenous EFs, the results of their alteration, and the mechanisms by which cells may sense these weak fields. Understanding the mechanisms by which native and applied EFs direct development and repair will enable current and future therapeutic applications to be optimized.

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Electrophoresis, Zeta potential and Surface Charges of Barley Mesophyll Protoplasts

Cited by 37 publications

References 0 publications

Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Use of a Gouy-Chapman-Stern Model for Membrane-Surface Electrical Potential to Interpret Some Features of Mineral Rhizotoxicity

Extracellular Electrical Fields Direct Wound Healing and Regeneration

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Electrophoresis, Zeta potential and Surface Charges of Barley Mesophyll Protoplasts

Cited by 37 publications

References 0 publications

Interactive Effects of Al3+, H+, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Interactive Effects of Al3+, H+, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Use of a Gouy-Chapman-Stern Model for Membrane-Surface Electrical Potential to Interpret Some Features of Mineral Rhizotoxicity

Extracellular Electrical Fields Direct Wound Healing and Regeneration

Contact Info

Product

Resources

About

Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential

Interactive Effects of Al³⁺, H⁺, and Other Cations on Root Elongation Considered in Terms of Cell-Surface Electrical Potential