Oryzalin-induced changes in water status and cytoskeleton proteins of winter wheat seedlings upon cold acclimation and ABA treatment

The effect of oryzalin (a specific inhibitor of tubulin polymerization in plant cells) on water retention by the leaves and roots of winter wheat (Triticum aestivum L.) seedlings was studied. The cultivars differing in their frost resistance were compared after their acclimation to low temperature (3°C for 3 or 7 days) and after treatment with ABA. In control untreated plants, oryzalin reduced the water-retaining capacity (WRC) of leaves and roots. Both hardening and ABA lowered the effect of the inhibitor on WRC in leaves, whereas their effects on water retention by roots were opposite, i.e., hardening weakened and ABA intensified the effect of oryzalin. Oryzalin-induced reduction of WRC decreased in the following sequence of cultivars: weakly frost resistant → moderately frost resistant → highly frost resistant. It was more pronounced in the leaves than in the roots, the latter being characterized by the lower WRC and lower frost resistance. After three-day-long hardening of plants, an additive effect of hypothermia and ABA on oryzalin-induced decrease in WRC of leaves and the lack of such effect in the roots were observed. The immunochemical analysis of the composition and content of cytoskeletal proteins with Western blotting showed that in the leaves the actin/tubulin ratio was higher than in the roots. The treatment of nonacclimated plants with ABA lowered the content of α- and β-tubulins and actin in roots but did not affect the level of actin in leaves. Hardening negated the effects of ABA on cytoskeletal proteins. Oryzalin produced the greatest inhibitory effect on WRC and an increase in frost resistance in ABA-treated plants in the experiments with leaves of the weakly frost resistant cultivar before and after hardening. Organ- and cultivar-specific and ABA-mediated dependence of WRC on cytoskeletal proteins and microtubules and microfilaments formed by them is supposed to result from their effect on the state of intracellular water and water permeability of the plasma membrane. In the course of cold acclimation of plants and upon their treatment with ABA, this dependence was more distinctly expressed in leaves than in roots, and especially in the plants of the weakly frost resistant cultivar

Cell-wall lectins during winter wheat cold hardening

The polypeptide composition and functional activity of cell-wall lectins from roots of winter wheat (Triticum aestivum L., cv. Mironovskaya 808) seedlings during cold hardening were studied. Several phases of lectin activity changes were observed, which indicates their involvement in the development of general adaptation syndrome of the cell. After 0.5-h low-temperature treatment, marked alterations occurred in the profile of protein elution: lectins with mol wts of 78 and 42.5 kD disappeared and new ones with mol wts of 72, 69, 37, and 34.5 kD appeared. It was established that 17.5-and 69-kD lectins and most lectins eluted with glucose were arabinogalactan proteins (AGP), which permitted a supposition that these lectins were involved in the interaction between the cell wall and cytoskeleton. After 7-day-long hardening, total protein content reduced and lectins with mol wts of 69 and 37 kD disappeared, which corresponded to reduced lectin activity by the end of hardening. A transient appearance of 37-and 69-kD lectins, which are AGP, might indicate their involvement in the triggering the development of plant-cell defense responses. © 2006 Nauka/Interperiodica

Effect of cartolin on oryzalin-induced changes in lectin activity during low-temperature plant hardening

The effect of cartolin (0.33 μM), an antistress regulator of cytokinin type, on the cytoskeleton-dependent changes in lectin activity in the roots of unhardened (23°C) and cold-hardened (3°C, 7 days) 7-day-old plants of three cultivars of winter wheat (Triticum aestivum L.) was studied. In unhardened plants, cartolin increased activity of soluble and cell wall-bound lectins in a cultivar-specific mode. This is evidently important for subsequent enhancement of adaptation processes in the cell. The inhibitor of microtubule polymerization, oryzalin, reduced the activity of soluble lectins and increased that of cell wall-bound lectins. A reduced sensitivity of lectin activity to oryzalin after cartolin treatment could result from its stabilizing action on the cytoskeletal structures and on the interaction between cell-wall lectins and microtubules. The most efficient cartolin action, the suppression of oryzalin effect on lectin activity in hardened plants, was observed in the frost-sensitive wheat cultivar. It is likely that cartolin treatment is more efficient in the activation of adaptation processes occurring with the involvement of cytoskeletal structures in the cultivars of lower tolerance. © 2008 MAIK Nauka

Photosynthetic carbon metabolism in potato leaves under changes in light intensity

© 2016, Pleiades Publishing, Ltd. Photosynthetic assimilation of 14CO2 was examined in leaves of potato (Solanum tuberosum L.) plants that were grown under direct sunlight and then transferred to 50% irradiance for various periods. The rate of 14CO2 assimilation correlated with light intensity: the photosynthetic rate reduced by 52% after 5-day shading and by 70% after 30-min shading. In all shaded and shade-adapted plants, the sucrose/hexose ratio decreased by a factor of 3.5–4.1; furthermore, the radioactivity of glycolate cycle metabolites and the serine/glycine ratio were lowered. In plants shaded for 5 days or 30 min, the radioactivity of aspartate and malate was higher than at continuous high irradiance, especially in plants shaded for 30 min, whereas a sudden illumination of the shaded plants reduced the radioactivity of these substances. We suppose that low irradiance averted the reentry of glycolate path carbon into the Calvin cycle and redirected this carbon source for the production of four-carbon acids that acidified the apoplast. This acidification activated the apoplastic invertase, which enhanced sucrose hydrolysis and hindered the sucrose export from the leaf. Hydrolysis of sucrose promoted the increase in osmolarity of the apoplastic solution, this increase being stronger at close distances to the stomatal pores where water is intensely evaporated. The increase in osmolarity of extracellular medium led to closing of stomata and the suppression of photosynthesis

Cytoskeleton-induced alterations of the lectin activity in winter wheat under cold hardening and abscisic acid (ABA)

The roots and leaves of 7-day seedlings of three winter wheat cultivars differing in frost resistant were used to study changes in lectin activity under cytoskeleton modifiers (DMSO - 7%; colchicine - 1 mM; oryzalin-15 μM; cytochalasin B - 15 μM) of non-hardened (23°C) and hardened (2-3°C, 3-7 day) plants. Plants were grown with ABA (30 μM) or without ABA. Pretreatment with colchicine, oryzalin [inhibitors of microtubules (MT) polymerization], cytochalasin B [inhibitor of microfilament (MF) polymerization] increased the activity of cell wall lectins, although pretreatment with DMSO (stabilizer of microtubules) decreased the activity. Both hardening and ABA decreased the effect of the cytoskeletal modifiers. These results could be explained by the appearance of tolerant MTs with less affinity. It is probable that increase in the activity of cell wall lectins may be the compensatory mechanism which stabilizes the cytoskeleton structure in conditions tending to disrupt it. The genotype with low resistance had higher sensitivity of lectin activity to cytoskeleton modifiers than the frost resistant genotype. The results suggest that leaves have more stable MTs and MFs and stronger MT-MF binding than roots. (C) 2000 Academic Press

Effect of modification of cell calcium status on lectin activity | Aktivnost' lektinov pri izmenenii kal'tsievogo statusa kletok.

Effects of oryzalin (10 microM), an inhibitor of microtubule polymerization, on the activity of soluble and cell wall lectins were studied in 7 day-old seedlings of unhardened (23 degrees C) and cold acclimated (7 days at 2-3 degrees C) winter wheat (Triticum aestivum L.). Seedlings were grown in the presence of 25 microM and 1 mM Ca2+, 500 microM verapamil, 250 microM chlorpromazine or without modifiers of calcium status in the medium. Inhibitor of the microtubule polymerization inhibitor, likely as inhibitors of Ca(2+)-signal, decreased the activity of soluble lectins and increased that of cell wall lectins. Apparently, injury of microtubule phosphorylation results in a more considerable microtubule disorganization, than that observed after oryzalin effect. A low Ca2+ concentration (25 microM) depressed, while a high concentration (1 mM) prompted microtubule sensibility to oryzalin. Such an effect of high Ca2+ concentration may be related to destabilizative action of Ca(2+)-calmodulin in these conditions, because chlorpromazine decreased oryzalin-induced increase in the activity of cell wall lectins with 1 mM Ca2+. It is concluded that the activity of cell wall lectins depends on the microtubule status that is regulated by calcium signal

Methods of probe microscopy in the study of topography and elastic properties of cold-resistant elastomers

The work was carried out under the financial support of the Russian Science Fund, grant 14-29-00198-П(sample preparation and scanning electron microscopy) and the Federal Agency of Scientific Organizations - Agreement No 007-ГЗ/Ч3363/26 (scanning probe microscopy)

Preclinical Investigations of the Efficacy of the Glutaminase Inhibitor CB-839 Alone and in Combinations in Chronic Lymphocytic Leukemia

INTRODUCTION: Chronic lymphocytic leukemia (CLL) cells are metabolically flexible and adapt to modern anticancer treatments. Bruton tyrosine kinase (BTK) and B-cell lymphoma-2 (BCL-2) inhibitors have been widely used to treat CLL, but CLL cells become resistant to these treatments over time. CB-839 is a small-molecule glutaminase-1 (GLS-1) inhibitor that impairs glutamine use, disrupts downstream energy metabolism, and impedes the elimination of reactive oxygen species. METHODS: To investigate the RESULTS: We found that CB-839 caused dose-dependent decreases in GLS-1 activity and glutathione synthesis. CB-839-treated cells also showed increased mitochondrial superoxide metabolism and impaired energy metabolism, which were reflected in decreases in the oxygen consumption rate and depletion of the adenosine triphosphate pool and led to the inhibition of cell proliferation. In the cell lines, CB-839 combined with venetoclax or AZD-5991, but not with ibrutinib, demonstrated synergism with an increased apoptosis rate and cell proliferation inhibition. In the primary lymphocytes, no significant effects of CB-839 alone or in combination with venetoclax, ibrutinib, or AZD-5991 were observed. DISCUSSION: Our findings suggest that CB-839 has limited efficacy in CLL treatment and shows limited synergy in combination with widely used CLL drugs

New behavioral forms of sportsman students identification in university digital educational reality

The relevance of the research is due to a wide range of changes in the University educational reality caused by the influence of the Internet, computers, smartphones, mobile devices and modern gadgets on the behavioural forms of student identification. These processes are becoming a matter of particular concern to the public and University teachers. In this regard, this study reveals the features of the value priorities of the University digital educational reality, which modify the behavioural forms of student identification. In the course of pedagogical modelling, which is the leading research method, the phenomenon of new behavioural forms of student identification is identified as the leading idea of the University digital educational reality. This article reveals the key values of student identity identification in the University digital educational reality. The structure and content of new behavioural forms of student identification are established. Based on the research materials, the correction module of new behavioural forms of student identification in the University digital educational reality is justified. The module effectiveness is proved by the results of using new behavioural forms of student identification in the University educational process. The materials of the article are recommended to teachers, methodologists, organizers of the educational process and University students

Effect of silencing of the apoplastic invertase gene on photosynthesis in tomato

© 2015 Pleiades Publishing, Ltd. Photosynthesis was examined in wild-type tomato plants (Lycopersicon esculentum L., cv. Money-maker) and in the transformants where gene expression of the leaf apoplastic invertase was suppressed by RNA interference (Lin8-RNAi). The influence of genetic transformation on photosynthesis depended on the demand for assimilates by sink organs. Using growth pots with low amount of soil, we found that at the initial growth stage when growth processes were particularly active, photosynthesis in Lin8-RNAi plants was higher than in the wild-type plants. As the reserves of mineral nutrients were gradually exhausted, photosynthesis decreased in both plant groups, but the decrease was more extensive in Lin8-RNAi plant form. Analysis of the distribution of 14C among the photosynthates produced after 3-min period of 14CO2 assimilation revealed the decreased incorporation of 14C into hexoses in Lin8-RNAi plants and the increased incorporation of 14C into aspartate and products of the glycolate pathway. Supplementing the soil with nitrate nitrogen as a fertilizer enhanced the non-carbohydrate trend of photosynthesis, but this trend was less pronounced in the transformed plants. Simultaneous measurements of CO2-exchange and H2O release revealed an insignificant increase in Lin8-RNAi plants of photosynthetic activity, transpiration, and intraleaf CO2 concentration. However, in 30–50 min after lowering the photon flux density from 1556 to 771 μmol/(m2 s) photosynthesis was reduced in both genotypes, whereas transpiration was diminished in wild-type plants and increased in the Lin8-RNAi form. It is concluded that the apoplastic invertase regulates photosynthesis through changes in osmolarity of the apoplastic fluid that controls the opening of stomata