Dynamics of structural and functional changes in wheat root cells under the action of protonophore

Structural and functional changes in wheat root cells during long-term action of a protonophore--carbonyl cyanide 3-chlorophenylhydrazone (CCCP)--were studied. It was demonstrated that CCCP affected the electrical potential and inward resistance of cells, increased K+ ions release to the incubation medium, inhibits oxygen uptake for 1-4 h, which was followed by oxygen uptake stimulation for 6 h of treatment. These changes of physiological processes were accompanied with a variety of ultrastructural changes in cell organization, namely in the structure of mitochondria, endoplasmic reticulum canals, and the nucleus. The role of protons is discussed, in particular, in the regulation of metabolic state of mitochondria, and in general regulation of structural and functional conditions of cells.     

Cytoskeletal changes in A-431 cells under the action of epidermal growth factor]

By the use of rhodamine-phalloidin, the distribution of actin in A-431 cells during the action of epidermal growth factor (EGF) has been studied. Changes in the pattern of staining are observed in 30-60 s after addition of the EGF. Microvilli and wrinkles are created on the cell surface. Following a 5-10 min action of EGF, rhodamine-phalloidin stained intensely ruffles and cell borders. After 60 min, the ruffling of cell surface disappeared, and actin was seen concentrating on the cell borders only. Electron microscopy of the EGF-treated A-431 cells lysed by Triton X-100 also revealed some vigorous fibrillar bunches on the cell edges.     

The molecular mechanism of action of the proton ionophore FCCP (carbonylcyanide p-trifluoromethoxyphenylhydrazone).

We propose a simple model that accounts for the ability of the weak acid FCCP (Carbonylcyanide-p-trifluoromethoxyphenylhydrazone) to both transport protons across phospholipid bilayer membranes and uncouple oxidation from phosphorylation in mitochondria. Four parameters are required to characterize this model: the rate constant for the movement of A- across the membrane, kA, the rate constant for the movement of HA across the membrane, kHA, the adsorption coefficient of A- onto the membrane-solution interface, beta A, and the surface pK. These four parameters were determined from kinetic measurements on planar bilayer membranes using the charge-pulse and voltage-clamp techniques. We confirmed the adequacy of the model by determining each of these parameters independently, utilizing equilibrium dialysis, zeta potential, membrane potential, spectrophotometric, and conductance measurements. For a phosphatidylethanolamine bilayer the values of the parameters are kHA = 10(4)S-1, beta A = 3 10(-3) cm, and 6.0 less than pK less than 6.4. As predicted theoretically, the value of KA depends on both the applied voltage, V, and dielectric constant of the membrane, epsilon r; when V approaches zero and the membrane contains chlorodecane (epsilon r congruent to 2.7) kA = 700 s-1. If oxidation is coupled to phosphorylation by means of a delta microH+, and V er congruent to 2.7 for the inner membrane of the mitochondrion, the model predicts that FCCP should exert maximal uncoupling activity at a pH congruent to pK. This prediction agrees with the published experimental results.     

Structural-functional changes in the peripheral nerves after administration of several drugs]

Structural and functional changes in the sciatic nerve induced by some drugs were studied using morphological and electrophysiological methods. It was stated that the application of this drug on the nerve causes different degenerating changes. Electrophysiological data, using the regeneration of action potential, proved the presence of structural changes in the nerve after application of mentioned drugs and showed partly preserved conduction of the nerve trunks.     

Structural-functional status of the cardiomyocyte cell membrane under experimental pathology

The results of research conducted on the cardiomyocytes plasma membranes structural and functional state under the experimental stress and atherosclerosis are displayed in this article. These experimental pathology is determined to be accompanied by some stereotypic quantitative and qualitative modifications occurred in the lipid matrix of the cardiomyocytes plasma membranes--increase of cholesterol content, decrease of phospholipids, accumulation of lisophospholipids and fatty acid. There are demonstrated results that the experimental stress has an atherogenic effect on the plasma membranes of cells by imputting the cholesterol into the membrane even in the intact animals with normal lipid metabolism. All these modifications are also accompanied by the activation of free-radical oxidation. All these changes are capable to lie in the basis of physical and chemical properties mechanism modification of membranes: modification of lipid matrix, change of viscosity, ion-transport properties of cardiomyocytes membranes, oppression of Na+, K(+)-ATPase activity.     

Structural-functional changes in plasma lipoproteins during vitamin D-deficient rickets in children

The lipid composition and structure of low- and high-density lipoproteins (LDL and HDL) have been studied in children with the vitamin D-deficient rachitis. An increase of the cholesterol content in the atherogenic LDL against a background of its decrease in the antiatherogenic HDL has been revealed, that is analogous to the observed changes under the atherosclerosis development in adults. Due to the studies in the amino acidic composition and determination of the nature and quantity of the charged groups of lipoprotein particles accessible for titration definite, certain disturbance in the structure of lipoproteins are observed as such that may cause disturbances in their functional activity.     

Salinity-induced changes in the structure and ultrastructure of bean root cells

The effect of 80 mM NaCl on the structure and ultrastructure of root cells ofPhaseolus vulgaris plants has been investigated. Roots of plants treated with NaCl were shorter and had less secondary roots than control plants. In control plants, epidermal cells were isodiametric and uniformly placed forming a thin layer, whereas in stressed plants, the shape and disposition of epidermal cells was less regular. The cortical cells of control plant were round-shaped and distributed allowing large and well defined intercellular spaces, whereas stressed plants presented irregular cells, which were interdigitated, thus decreasing the volume of the intercellular spaces. Presence of 80 mM NaCl did not result in significant differences in the number, shape or distribution of the cell organelles. Membrane vesiculation was often observed in cells of NaCl treated plants. Addition of 80 mM NaCl to the growth medium considerably increased the leakage of solutes from intact plant roots back to the solution especially K⁺ and Ca²⁺.     

Structural-functional changes in the cardiovascular system during high athletic activity in aboriginals of Yakutia

To study structural-functional changes in the cardiovascular system and metabolic characteristics in residents of Yakutia who were engaged in sports activities, 146 Yakut men 18–29 years old living in Yakutsk were examined. The basic group consisted of elite athletes (free-style wrestling and boxing) (n = 108; average age, 20.2 ± 0.2 years). The control group consisted of untrained healthy men (n = 38; average age, 24.5 ± 0.4 years). The examination included primary inspection, anthropometry, echocardiography, integral rheography of the body, measurement of blood pressure (BP), and biochemical analysis of blood serum. The basic group was divided into two subgroups depending on the BP level (Ia, with optimal and normal BP; Ib, with high normal BP).     

The action of adaptogenic preparations on vacuolar proton pumps activity in corn root cells under salt stress conditions

The function of two electrogenic H+ -pumps in plant vacuolar membrane (tonoplast) and their response to the salt stress conditions and adaptogenic preparations have been studied. Experiments were carried out on tonoplast fraction isolated from the roots of corn seedlings grown in water culture which were exposed at 7-day age in the presence of 0.1 M NaCl during 1 or 10 days. The role of every H+ -pump in potential generation was elucidated by assaying transport and hydrolytic activity of enzymes--V-type H+ -ATPase and H+ pyrophosphatase represented their mechanisms. It was found in the control variant that transport activity H+ -PPase exceeded considerably H+ -ATPase one in the tonoplast from 7-day seedlings. However this situation was changed in 18-day seedlings by H+ -ATPase transport activity increasing with age whereas its hydrolytic one was decreased. Both NaCI expositions caused the progressive decrease of transport and hydrolytic activity of H+ -PPase whereas H+ -ATPase responded to this factor by increasing transport activity, while its hydrolytic one fell. Bioactive preparations Methyure and Ivine (10(-7) M) used by seed soaking caused a further increase of H+ -ATPse transport activity especially in the presence of NaCl whereas H+ -PPase one was not changed. Methyure effect in these experiments was more pronounced. Obtained results demonstrated participation of tonoplast H+ -pumps in plant adaptation to NaCI which can be realized by amplification of Na+ -H(+) antiporter energization. An important role of vacuolar H+ -ATPase in growth and adaptation processes in plants has been proved.     

A mycorrhizal fungus changes microtubule orientation in tobacco root cells

Summary Cortical cells of mycorrhizal roots undergo drastic morphological changes, such as vacuole fragmentation, nucleus migration, and deposition of cell wall components at the plant-fungus interface. We hypothesized that the cytoskeleton is involved in these mechanisms leading to cell reorganization. We subjected longitudinal, meristem to basal zone, sections of uninfectedNicotiana tabacum roots to immunofluorescence methods to identify the microtubular (MT) structures associated with root cells. Similar sections were obtained from tobacco roots grown in the presence ofGigaspora margarita, an arbuscular mycorrhizal fungus which penetrates the root via the epidermal cells, but mostly develops in the inner cortical cells. While the usual MT structures were found in uninfected roots (e.g., MTs involved in mitosis in the meristem and cortical hoops in differentiated parenchyma cells), an increase in complexity of MT structures was observed in infected tissues. At least three new systems were identified: (i) MTs running along large intracellular hyphae, (ii) MTs linking hyphae, (iii) MTs binding the hyphae to the host nucleus. The experiments show that mycorrhizal infection causes reorganization of root MTs, suggesting their involvement in the drastic morphological changes shown by the cortical cells.     

Structural-functional state of thylakoid membranes of wheat genotypes under water stress

Plants were grown in field conditions in the wide area under normal water supply and severe water deficit. Two wheat (Triticum aestivum L.) genotypes contrasting by architectonics and differing in drought-resistance were used: Giymatli-2/17, short stature, with broad and drooping leaves, drought-sensitive, and Azamatli-95, short stature, with vertically oriented small leaves, drought-tolerant). It was found out that Giymatli-2/17 was characterized by relatively low content of Chl a-protein of PS I (CP I) and β-subunit of ATP-synthase complex, the high content of proteins in the 33-30.5 kDa region and LHC polypeptides (28-24.5 kDa), the intensive fluorescence at 740 nm and more high photochemical activity of PS II under normal irrigation compared with Azamatli-95. However, the content of CP I (M_r 115 kDa) and apoprotein of P700 with M_r 63 kDa insignificantly increases in the drought-resistant genotype Azamatli-95 under extreme water supply condition while their content decreases in drought-sensitive cv Giymatli-2/17. Intensity of synthesis α- and β-subunits of CF₁ (55 and 53.5 kDa) also decreases in Giymatli-2/17. The levels of the core antenna polypeptides of FS II with M_r 46 and 44.5 kDa (CP47 and CP43) remains stable both in normal, and stressful conditions. At the same time the significant reduction is observed in the content of polypeptides in the 33-30.5 kDa region in the more sensitive genotype Giymatli-2/17. There is an increase in the LHC II polypeptides level in tolerant genotype Azamatli-95 in contrast to Giymatli-2/17 (where the content of these subunits is observed decreasing). The intensity of short wavelength peaks at 687 and 695 nm sharply increases in the fluorescence spectra (77 K) of chloroplasts from sensitive genotype Giymatli-2/17 under water deficiency and there is a stimulation of the ratio of fluorescence band intensity F687/F740. After exposure to drought, cv Giymatli-2/17 shows a larger reduction in the actual PS II photochemical efficiency of chloroplasts than cv Azamatli-95.     

Structural-functional state of thylakoid membranes of wheat genotypes under water stress

Plants were grown in field conditions in the wide area under normal water supply and severe water deficit. Two wheat (Triticum aestivum L.) genotypes contrasting by architectonics and differing in drought-resistance were used: Giymatli-2/17, short stature, with broad and drooping leaves, drought-sensitive, and Azamatli-95, short stature, with vertically oriented small leaves, drought-tolerant). It was found out that Giymatli-2/17 was characterized by relatively low content of Chl a-protein of PS I (CP I) and beta-subunit of ATP-synthase complex, the high content of proteins in the 33-30.5 kDa region and LHC polypeptides (28-24.5 kDa), the intensive fluorescence at 740 nm and more high photochemical activity of PS II under normal irrigation compared with Azamatli-95. However, the content of CP I (M(r) 115 kDa) and apoprotein of P700 with M(r) 63 kDa insignificantly increases in the drought-resistant genotype Azamatli-95 under extreme water supply condition while their content decreases in drought-sensitive cv Giymatli-2/17. Intensity of synthesis alpha- and beta-subunits of CF(1) (55 and 53.5 kDa) also decreases in Giymatli-2/17. The levels of the core antenna polypeptides of FS II with M(r) 46 and 44.5 kDa (CP47 and CP43) remains stable both in normal, and stressful conditions. At the same time the significant reduction is observed in the content of polypeptides in the 33-30.5 kDa region in the more sensitive genotype Giymatli-2/17. There is an increase in the LHC II polypeptides level in tolerant genotype Azamatli-95 in contrast to Giymatli-2/17 (where the content of these subunits is observed decreasing). The intensity of short wavelength peaks at 687 and 695 nm sharply increases in the fluorescence spectra (77 K) of chloroplasts from sensitive genotype Giymatli-2/17 under water deficiency and there is a stimulation of the ratio of fluorescence band intensity F687/F740. After exposure to drought, cv Giymatli-2/17 shows a larger reduction in the actual PS II photochemical efficiency of chloroplasts than cv Azamatli-95.