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1.
Ion exchange properties of plant root cell walls 总被引:1,自引:0,他引:1
Acid-base properties and the swelling capacity of wheat, lupin and pea root cell walls were investigated. Roots of seedlings and green plants of different age were analysed by the potentiometric method. The ion exchange capacity (S
i) and the swelling coefficient (K
cw) of root cell walls were estimated at various pH values (from 2 to 12) and at different ionic strength (between 0.3 and 1000 mM). To analyse the polysigmoid titration curves pHi = f (S
i), the Gregor's equation was employed. It was shown that the Gregor's model fits well the experimental data. The total number of the cation exchange (S
t
cat) and the anion exchange (S
t
an) groups were determined in the root cell walls. The number of the functional group of each type (S
j) was estimated, and the corresponding values of pK
a
j were calculated. It was shown that for all types of cation exchangeable groups arranged in the cell wall structure the acid properties are enhanced by the increasing concentration of electrolyte. For each ionogenic group the coefficients of Helfferich's equation [pK
a
j = f (C
K+)] were determined. It was found that the swelling of root cell walls changes with pH, C
K+ and strongly depends on plant species. Within the experimental pH and C
K+ range the swelling coefficient changes as follows: lupin > pea > wheat. The obtained results show that for the plant species under investigation the differences in the swelling coefficients originate from (a) the differences in the cross-linking degrees of polymeric chains arranged in the cell wall structure, (b) the differences in the number of carboxyl groups and (c) the differences in the total number of functional groups. Based on the estimated swelling coefficients in water it could be inferred that for wheat the cross-linking degree of the polymeric chains in the root cell walls is higher than those for lupin or pea. It has been emphasized that the calculated parameters (S
j, pK
a
j, K
cw), the equation {pK
a
j = f (CK+)} and the dependencies {K
cw = f (CK+, pH)} allow to estimate quantitatively the changes in the ion exchange capacity of the root cell walls in response to the changes in an ionic composition of an outer solution. The results of these estimations allow to suggest that (a) the root apoplast is a compartment where the accumulation of cations takes place during the first stage of cation uptake from an outer medium, and (b) the accumulation degree is defined by pH and ionic composition of an outer solution. On the basis of the literature review and the results of the present experimental study it was proposed that the changes in the cell wall swelling in response to variances of environmental or experimental conditions could lead to a change of the water flow through a root apoplast. It has been supported that there is direct relationship between the swelling of root cell walls and the water flow within the plant root apoplast. 相似文献
2.
3.
M. A. Breygina N. P. Matveyeva D. S. Andreyuk I. P. Yermakov 《Russian Journal of Developmental Biology》2012,43(2):85-93
We studied the possibility of K+ and Cl− efflux from tobacco pollen grains during their activation in vitro or on the stigma of a pistil. For this purpose the X-ray
microanalysis and spectrofluorometry were applied. We found that the relative content of potassium and chlorine in the microvolume
of pollen grain decreases during its hydration and activation on stigma. Efflux of these ions was found both in vivo and in
vitro. In model in vitro experiments anion channel inhibitor NPPB ((5-nitro-2-(3-phenylpropylamino) benzoic acid) in the concentration
that was blocking pollen germination, reduced Cl− efflux; potassium channel inhibitor TEA (tetraethylammonium chloride) partially reduced K+ efflux and lowered the percent of activated cells. Another blocker of potassium channels Ba2+ caused severe decrease in cell volume and blocked the activation. In general, the obtained data demonstrates that the initiation
of pollen germination both in vivo and in vitro involves the activation of K+ and Cl− release. An important role in these processes is played by NPPB-, TEA- and Ba2+-sensitive plasmalemma ion channels. 相似文献
4.
N. R. Meichik N. I. Popova Yu. I. Nikolaeva I. P. Yermakov A. N. Kamnev 《Applied Biochemistry and Microbiology》2011,47(2):176-181
Research into ion-exchange properties of cell walls isolated from thallus of red seaweed Phyllophora crispa was carried out. Ion-exchange capacity and the swelling coefficient of the red alga cell walls were estimated at various
pH values (from 2 to 12) and at constant ionic strength of a solution (10 mM). It was established that behavior of cell walls
as ion-exchangers is caused by the presence in their matrix of two types of cation-exchange groups and amino groups. The amount
of the functional group of each type was estimated, and the corresponding values of pK
a
were calculated. It can be assumed that ionogenic groups with pK
a
∼5 are carboxyl groups of uronic acids, and ionogenic groups with pK
a
∼7.5 are carboxyl groups of the proteins. Intervals of pH in which cation-exchange groups are ionized and can take part in
exchange reactions with cations in the environment are defined. It was found that protein was a major component of cell wall
polymeric matrix because its content was 36%. 相似文献
5.
In cytotoxicity and indirect immunofluorescence tests an antiserum to ACA-1 (activated cell antigen) reacted with 58–100% of actively proliferating cells from tumors of lymphoid (EL-4 T lymphoma, MOPC 104E plasmacytoma) and nonlymphoid origin (AH-22 hepatoma, Sa-1 and MCh-11 sarcomas, F2 mammary cancer). Absorption of anti-ACA-1 serum with tumor cells sharply reduced its activity both against the cells of all these neoplasms and against normal activated T and B lymphocytes. Absorption with proliferating murine cells from the brain of embryos and the retina of neonates or with similar (nonproliferating) cells from adult mice did not affect the activity of the antiserum. It is concluded that ACA-1 is expressed on actively proliferating cells of the tumors studied. 相似文献
6.
Acid–base properties of cell walls isolated from various root tissues of 7-day-old lupine seedlings and 14-day-old lupine plants grown in various media were studied. The ion-exchange capacity of root cell walls was estimated at various pH values (from 2 to 12) and constant ionic strength (10 mM). The parameters determining the qualitative and quantitative composition of cell wall ionogenic groups along the root length and in its radial direction were estimated using Gregor's model. This model fits the experimental data reasonably well. Four types of ionogenic groups were found in the cell walls: an amino group (pK
a 3), two types of carboxylic groups (pK
a 5 and 7.3, the first being the carboxylic group of galacturonic acid), and a phenolic group (pK
a 10). The number of functional groups of each type was estimated, and the corresponding ionization constant values were calculated. It is shown that the chemical composition of the ionogenic groups was constant along the root length as well as in its radial direction and did not depend on either physiological state or root nutrition, while the number of different groups varied. The content of carboxylic groups of -D-polygalacturonic acid in the root cell walls of 14-day-old plants was shown to depend on the distance from the root tip, being maximal in the zone of lateral roots. The number of these groups was 10- and 2-fold less in the central cylinder compared to that of cortex for 14-day-old plants and 7-day-old seedlings, respectively. 相似文献
7.
Ion homeostasis plays a central role in polarisation and polar growth. In several cell types ion channels are controlled by reactive oxygen species (ROS). One of the most important cells in the plant life cycle is the male gametophyte, which grows under the tight control of both ion fluxes and ROS balance. The precise relationship between these two factors in pollen tubes has not been completely elucidated, and in pollen grains it has never been studied to date. In the present study we used a simple model – protoplasts obtained from lily pollen grains at the early germination stage – to reveal the effect of H2O2 on cation fluxes crucial for pollen germination. Here we present direct evidence for two ROS‐sensitive currents on the pollen grain plasma membrane: the hyperpolarisation‐activated calcium current, which is strongly enhanced by H2O2, and the outward potassium current, which is modestly enhanced by H2O2. We used low concentrations of H2O2 that do not cause an intracellular oxidative burst and do not damage cells, as demonstrated with fluorescent staining. 相似文献
8.
O. N. Yermakova A. M. Yermakov Kh. P. Tiras V. V. Lednev 《Russian Journal of Developmental Biology》2009,40(6):382-385
The melatonin effect on the anterior and posterior ends of a free-living flatworm Girardia tigrina was studied, as well as the variability of the mitotic activity of the stem cells (neoblasts) in the anterior and posterior
postblasteme. This hormone may inhibit the regeneration of the anterior end of the animal in the physiologic-friendly concentrations
of 10−10–10−5 M by suppressing the mitotic activity of the neoblasts. This hormone does not affect the posterior end’s regeneration; thus,
its regeneration effect is significantly elective. 相似文献
9.
Ion-exchange properties of cell walls in chickpea cultivars with different sensitivities to salinity
N. R. Meychik I. P. Yermakov S. D. Khonarmand Yu. I. Nikolaeva 《Russian Journal of Plant Physiology》2010,57(5):620-630
Ion-exchange properties of polymeric matrices were compared for cell wall preparations isolated from roots and shoots of two
cultivars of Cicer arietinum L. (cvs. Bivanij and ILC 482) with different sensitivities to salinity. Irrespective of growth conditions, the cell walls
contained four types of ionogenic groups: amino groups, carboxyl groups of uronic and hydroxycinnamic acids, and phenolic
hydroxyl groups. Regardless of the salt concentration in the medium, the cells walls of different chickpea cultivars and from
different organs of the same plant were similar in qualitative composition of ionogenic groups, although quantities of ionogenic
groups per unit dry wt of cell walls varied depending on external and internal factors. Irrespective of the external medium
salinity, the cation-exchange capacity of cell walls, expressed per unit dry wt, decreased in a sequence: stem > root ∼ bottom
leaves > upper leaves. The volume of chickpea cell walls was found to vary depending on ionic composition and pH of the incubation
medium. The results were analyzed in the context of cell wall involvement in responses of C. arietinum to elevated salinity. 相似文献
10.
A. V. Smirnova N. P. Matveyeva I. P. Yermakov 《Plant biology (Stuttgart, Germany)》2014,16(1):252-257
Production and scavenging of reactive oxygen species (ROS) in somatic plant cells is developmentally regulated and plays an important role in the modification of cell wall mechanical properties. Here we show that H2O2 and the hydroxyl radical (?OH) can regulate germination of tobacco pollen by modifying the mechanical properties of the pollen intine (inner layer of the pollen wall). Pollen germination was affected by addition of exogenous H2O2, ?OH, and by antioxidants scavenging endogenous ROS: superoxide dismutase, superoxide dismutase/catalase mimic Mn‐5,10,15,20‐tetrakis(1‐methyl‐4‐pyridyl)21H, 23H‐porphin, or a spin‐trap α‐(4‐pyridyl‐1‐oxide)‐N‐tert‐butylnitrone, which eliminates ?OH. The inhibiting concentrations of exogenous H2O2 and ?OH did not decrease pollen viability, but influenced the mechanical properties of the wall. The latter were estimated by studying the resistance of pollen to hypo‐osmotic shock. ?OH caused excess loosening of the intine all over the surface of the pollen grain, disrupting polar growth induction. In contrast, H2O2, as well as partial removal of endogenous ?OH, over‐tightened the wall, impeding pollen tube emergence. Feruloyl esterase (FAE) was used as a tool to examine whether H2O2‐inducible inter‐polymer cross‐linking is involved in the intine tightening. FAE treatment caused loosening of the intine and stimulated pollen germination and pollen tube growth, revealing ferulate cross‐links in the intine. Taken together, the data suggest that pollen intine properties can be regulated differentially by ROS. ?OH is involved in local loosening of the intine in the germination pore region, while H2O2 is necessary for intine strengthening in the rest of the wall through oxidative coupling of feruloyl polysaccharides. 相似文献