scholarly journals The Location of the Donnan Free Space in Disks of Beetroot Tissue

1965 ◽  
Vol 18 (3) ◽  
pp. 547 ◽  
Author(s):  
MG Pitman
Keyword(s):  
Cation Exchange ◽  
Free Space ◽  
Cell Walls ◽  
Donnan Free Space

This paper describes experiments which show that the cell walls of beetroot tissue contain sufficient cation�exchange sites to account for at least 95% of the Donnan free space (D.F.S.) as measured by Briggs, Hope, and Pitman (1958). The contribution of the cytoplasm to the D.F.S. in their measurements was therefore less than 5%. The exchange sites in the D.F.S. of the tissue and in the cell walls have the same pKa of about 2�8, and are considered to be due to bound Ilronic acids.

Ion behavior in plant cell walls. II. Measurement of the Donnan free space, anion-exclusion space, anion-exchange capacity, and cation-exchange capacity in delignified Sphagnum russowii cell walls

1989 ◽  
Vol 67 (2) ◽  
pp. 460-465 ◽  
Author(s):  
Conrad Richter ◽  
Jack Dainty
Keyword(s):  
Cation Exchange ◽  
Anion Exchange ◽  
Free Space ◽  
Cell Walls ◽  
Cation Exchange Capacity ◽  
Dry Weight ◽  
Exchange Capacity ◽  
Anion Exchange Capacity ◽  
Anion Exclusion ◽  
Donnan Free Space

Isolated delignified cell walls from Sphagnum russowii Warnsdorf were incubated in various chloride salt solutions at neutral pH (pH 7 – 8), and ion sorption was measured directly by neutron activation analysis. The anion-exchange capacity was estimated to be 63 – 66 μequiv./g dry weight of wall material in the protonated form. The volume of the anion-exclusion space was 2.63 ± 0.21 (± SD, n = 3) and 1.65 ± 0.35 (± SD, n = 2) mL/g dry weight in NaCl and CaCl2, respectively. A novel approach to measure the Donnan free space is proposed: for walls equilibrated in a salt mixture containing 10 mequiv./L NaCl and 10 mequiv./L CaCl2, the Na+ ions can be considered "uncondensed" in the Manning sense. From the Donnan relationship for Na+ and Cl− ions in the internal and external phases, the Donnan free space was calculated to be 1.77 mL/g dry weight. Titrating walls from pH 2.1 to 9.1 in the presence of 10 mequiv./L NaCl and 10 mequiv./L CaCl2 revealed a maximum cation-exchange capacity above pH 6 of ca. 1900 μequiv./g dry weight. This corresponds to a fixed anionic charge concentration in the Donnan free space of 1.1 M. Key words: ion exchange, cell wall, Donnan free space.

scholarly journals Ionic Relations of Cells of Ohara Australis I. Ion Exchange in the Cell Wall

1959 ◽  
Vol 12 (4) ◽  
pp. 395 ◽  
Author(s):  
J Dainty ◽  
AB Hope
Keyword(s):  
Cell Wall ◽  
Ion Exchange ◽  
Free Space ◽  
Cell Walls ◽  
Plant Cells ◽  
External Solution ◽  
Exchangeable Cations ◽  
Intact Cells ◽  
Donnan Free Space ◽  
Isolated Cell

Measurements of ion exchange were made between isolated cell walls of Ohara australis and an external solution. Comparison between intact cells and cell walls showed that nearly all the easily exchangeable cations are located in the cell wall. The wall is hown to consist of "water free space" (W.F.S.) and "Donnan free space" (D.F.S.); the concentration of in diffusible anions in the D.F.S. is about O� 6 equivjl. This finding is contrary to past suggestions that the D.F.S. is in the cytoplasm of plant cells.

The Free Space of Citrus Leaf Slices

1975 ◽  
Vol 2 (3) ◽  
pp. 441 ◽  
Author(s):  
FA Smith ◽  
AL Fox
Keyword(s):  
Free Space ◽  
Cell Walls ◽  
Exchangeable Cations ◽  
Bathing Solution ◽  
Fresh Weight ◽  
Citrus Leaf ◽  
Orange Leaf ◽  
Donnan Free Space ◽  
Exchange Properties

Measurements of 36Cl and 22Na efflux have been used to estimate water free space and Donnan free space in Citrus (orange) leaf slices. The water free space within the slices amounts to about 0.025 ml/g fresh weight, suggesting that there is little infiltration of bathing solution into intercellular air spaces. The exchangeable cations of the Donnan free space within the slices total 20-25 μ-equiv/g fresh weight, and these values appear to reflect the exchange properties of the cell walls. The role of the free space as a 'reservoir' for ions in the intact leaf is discussed.

scholarly journals The Electric Double Layer and The Donnan Equilibrium in Relation to Plant Cell Walls

1961 ◽  
Vol 14 (4) ◽  
pp. 541 ◽  
Author(s):  
J Dainty ◽  
AB Hope
Keyword(s):  
Plant Cell ◽  
Free Space ◽  
Cell Walls ◽  
Double Layers ◽  
Approximate Theory ◽  
Plant Cell Walls ◽  
External Concentration ◽  
Charged Surfaces ◽  
Donnan Free Space ◽  
Electrically Charged

space in plant tissues into "water free space" (W.F.S.) and "Donnan free space" (D.F.S.) is examined in systems which contain electrically charged surfaces separated by various distances. It is suggested that plant cell walls should be described in terms of a system of electric double layers and not by classical Donnan equations. An approximate theory is presented which resl1lts in an expression for the equivalent width of D.F.S. in terms of the external concentration but which is independent of the surface charge density.

Free Space Characteristics of Barley Leaf Slices

1974 ◽  
Vol 1 (1) ◽  
pp. 65 ◽  
Author(s):  
MG Pitman ◽  
U Luttge ◽  
D Kramer ◽  
E Ball
Keyword(s):  
Free Space ◽  
Cell Walls ◽  
Surface Films ◽  
Fresh Weight ◽  
Intercellular Spaces ◽  
Barley Leaf ◽  
Intact Leaves ◽  
Donnan Free Space

Measurements are described of free space content of barley leaf slices. It is shown that the leaf slices contain a Donnan free space of about 3 µ-equiv/g fresh weight of tissue at a concentration of 300 mN, together with a water free space occupying 0.21 ml/g fresh weight. The Donnan free space is shown to be located in cell walls, as in other tissues (beet discs, barley roots) but the water free space is largely due to cut or damaged cells, injected intercellular spaces, and surface films of solution. The results are discussed in relation to free space of intact leaves.

Ion behavior in plant cell walls. I. Characterization of the Sphagnum russowii cell wall ion exchanger

1989 ◽  
Vol 67 (2) ◽  
pp. 451-459 ◽  
Author(s):  
Conrad Richter ◽  
Jack Dainty
Keyword(s):  
Cell Wall ◽  
Cation Exchange ◽  
Binding Sites ◽  
Cell Walls ◽  
Weak Acid ◽  
Wall Material ◽  
Plant Cell Walls ◽  
Donnan Free Space ◽  
Donnan Model

The ion-exchange properties of Sphagnum russowii cell wall material were studied in the context of the Donnan weak acid model. Titrations in the presence of Na+, Ca2+, or La3+ revealed two classes of weak acid binding sites, one with a low pK between 2 and 4 and the other with a high pK > 5. The total cation-exchange capacities of the low and high pK species were 1071 and 545 μequiv./g dry wt. wall material, respectively, and were related to the uronic, amino, and phenolic acid contents of the walls. Differences in pK estimates obtained in the presence of the different cations (pKNa > pKCa > pKLa) could not be explained by our semiarbitrary choice (1 mL/dry wt. wall material), for the effective volume (Donnan free space) bathing the exchange sites. It was concluded that valence-dependent reductions in cation activities in the wall phase are an important contributor to the differences in the pK estimates. Key words: cation exchange, cell wall, titration, Donnan model, weak acid.

Cation exchange in cell walls of gram-positive bacteria

1976 ◽  
Vol 22 (7) ◽  
pp. 975-982 ◽  
Author(s):  
Robert E. Marquis ◽  
Kathleen Mayzel ◽  
Edwin L. Carstensen
Keyword(s):  
Cation Exchange ◽  
Cell Walls ◽  
Divalent Cations ◽  
Teichoic Acid ◽  
Dry Weight ◽  
High Ionic Strength ◽  
Monovalent Cations ◽  
Anionic Sites ◽  
Gram Positive Bacteria ◽  
Anionic Groups

The relative affinities of various cations for anionic sites in isolated, bacterial cell walls were assessed by means of a technique involving displacement of one cation by another. The affinity series determined was [Formula: see text]. High affinity was correlated with low mobility of the bound ions in an electric field. The net cation-exchange capacities of walls isolated from a variety of bacteria were estimated by preparing the magnesium forms of the walls, washing them well with deionized water to remove supernumerary ions, and then completely displacing the magnesium with Na+ or H+. Total amounts of magnesium displaced varied from 73 μmol per gram dry weight, for walls of the teichoic acid-deficient 52A5 strain of Staphylococcus aureus to about 520 μmol per gram for Bacillus megaterium KM walls. The amount of displacable magnesium was inversely related to the physical compactness of the walls, except for walls of Streptococcus mutans GS-5. It was found that magnesium or calcium ions can each neutralize, or pair with, two anionic groups in walls suspended in ion-deficient media. Previous work had indicated that these ions may pair with only one anionic group at high ionic strength. Therefore, it appeared that there is a great deal of flexibility in the arrangement of charged groups in the wall. It was concluded also that for cells growing in commonly used laboratory media, which generally contain large excesses of monovalent versus divalent cations, there is a mix of small, cationic counterions in the wall and that monovalent cations may predominate even though the wall has higher affinity for divalent ions.

Salt relations of woody tissues. - I. Experiments with disks of wood

1968 ◽  
Vol 169 (1017) ◽  
pp. 379-397 ◽  
Keyword(s):  
Free Space ◽  
External Solution ◽  
Living Cells ◽  
Potential Difference ◽  
Radioactive Isotopes ◽  
Velocity Constant ◽  
Solutions Of Electrolytes ◽  
Woody Tissues ◽  
Donnan Free Space

Solutions of electrolytes when passing through the xylem undergo change in composition through interchange of ions with the walls of the cells, living and dead, and with the contents of the living cells. This interchange has been investigated in thin transverse sections of wood (mainly yew) in solutions labelled with radioactive isotopes (mainly 42 K and 82 Br). The uptake is assumed to proceed from the external solution via the ‘water free space’ (WFS) to the ‘Donnan free space’ (DFS) and the vacuoles of the living cells; for washing out the reverse. Of the total volume of yew wood about 37% is solids, about 4% is living cells, about 55% is WFS leaving about 4% DFS. The concentration of weak non-diffusible acid in the latter is about 0.8 equiv. I. -1 and its pK between 2 and 3. The velocity constant for the loss of 42 K from WFS to DFS is about 10 -2 s -1 when the wood is in equilibrium with 20 mM KCl. It is greater when the concentration is smaller and the potential difference between WFS and DFS is greater. The Q 10 of this constant is about 1.9. The efflux of potassium from the living cells is about 0.2 pequiv. cm -2 s -1 .

Biosynthèse des pectines et différenciation des fibres cellulosiques au cours de la croissance du lin

1989 ◽  
Vol 67 (1) ◽  
pp. 135-139 ◽  
Author(s):  
O. Morvan ◽  
A. Jauneau ◽  
C. Morvan ◽  
H. Voreux ◽  
M. Demarty
Keyword(s):  
Cell Wall ◽  
Cation Exchange ◽  
Cell Walls ◽  
Cation Exchange Capacity ◽  
Stem Elongation ◽  
Exchange Capacity ◽  
Pectin Content ◽  
Cellulose Deposition ◽  
Cellulosic Fibres ◽  
Elongation Phase

During the first stage of flax growth, stem elongation reaches 2.4 cm per day and the percentage of cell wall remains quite constant (4–15%). Cellulosic fibres develop principally during capsule formation and seed maturation. During the latter stage, the proportion of walls increases from 15 to 60% and the elongation is diminished to 0.5 cm per day. The lowering of the cation exchange capacity and of the pectin content of the cell walls during growth results principally from increased cellulose deposition in the fibre cells. The changes in the cation exchange capacity and in the percentage of cell wall show that when cellulose biosynthesis predominates, there is a continuous synthesis of pectins (10–15%) during the development of the plant. Methylated pectins are synthesized during the elongation phase. During maturation, the relative amounts of highly and less methylated pectins remain the same and thus it is not possible to determine what type of pectin is preferentially synthesized.

Cation-exchange capacity of plant cell walls at neutral pH

1985 ◽  
Vol 36 (11) ◽  
pp. 1065-1072 ◽  
Author(s):  
Michael S. Allen ◽  
Michael I. McBurney ◽  
Peter J. Van Soest
Keyword(s):  
Cation Exchange ◽  
Plant Cell ◽  
Cell Walls ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Plant Cell Walls ◽  
Neutral Ph
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