Agrogenic evolution of automorphic chernozems in the forest-steppe zone (Belgorod oblast)

Agrochronosequences of chernozems with different periods of their use in rainfed farming with application of traditional technologies have been studied in a typical forest-steppe area in Belgorod oblast. Certain stages in the development of these soils during more than two centuries of their agricultural use have been identifie

Effects of abscisic acid, low temperature, and plant age on cytoskeleton and phosphorylated proteins

The effects of exogenous abscisic acid (ABA), low temperature, and seedling age on the content of tubulin, actin, and phosphorylated proteins and the structural organization of microtubules (MTs) in cells of different tissues and organs of winter wheat cultivars contrasting in cold hardiness were studied by immunocytochemical methods using monoclonal (against alpha- and beta-tubulin and actin) and polyclonal (phosphothreonine) antibodies. The leaves and roots of five- and nine-day-old seedlings of three cultivars were characterized by unequal proportion of actin/tubulin proteins. ABA decreased the content of the cytoskeleton and the 60-kD phosphorylated proteins, thus promoting a decrease in the number of MTs and occurrence of a less branched network of weakly fluorescent tubulin components in the cells of the root differentiating zone (which is most responsible for the development of cold hardiness in wheat). Although the cold acclimation of plants (3°C, 7 days) did not change the level of tubulin and actin proteins, it evoked the spatial aggregation of MT, leading to formation of a dense network of tubulin cytoskeleton comprised of thick bundles of intensively fluorescent MTs. In the case of a combined action of the studied factors, low temperatures abolished the hormone effect described above, evoking an increase in the content of the cytoskeletal and 60-kD phosphorylated proteins and MT structures. We suggest that the ABA-induced decrease in the levels of proteins and MTs occurs at the initial stages of plant cold acclimation (3°C, 2-3 days). It may be the signal that triggers the processes of low-temperature adaptation. As the duration of cold acclimation increased (3°C, 7 days), the role of ABA in the formation of plant tolerance decreased. Apparently, in this case other hormone-independent mechanisms of frost hardiness development are triggered, in which the role of the cytoskeleton components and cytoskeleton-associated proteins increases

The Effects of Mechanical Preload on Transmural Differences in Mechano-Calcium-Electric Feedback in Single Cardiomyocytes: Experiments and Mathematical Models

Transmural differences in ventricular myocardium are maintained by electromechanical coupling and mechano-calcium/mechano-electric feedback. In the present study, we experimentally investigated the influence of preload on the force characteristics of subendocardial (Endo) and subepicardial (Epi) single ventricular cardiomyocytes stretched by up to 20% from slack sarcomere length (SL) and analyzed the results with the help of mathematical modeling. Mathematical models of Endo and Epi cells, which accounted for regional heterogeneity in ionic currents, Ca2+ handling, and myofilament contractile mechanisms, showed that a greater slope of the active tension–length relationship observed experimentally in Endo cardiomyocytes could be explained by greater length-dependent Ca2+ activation in Endo cells compared with Epi ones. The models also predicted that greater length dependence of Ca2+ activation in Endo cells compared to Epi ones underlies, via mechano-calcium-electric feedback, the reduction in the transmural gradient in action potential duration (APD) at a higher preload. However, the models were unable to reproduce the experimental data on a decrease of the transmural gradient in the time to peak contraction between Endo and Epi cells at longer end-diastolic SL. We hypothesize that preload-dependent changes in viscosity should be involved alongside the Frank–Starling effects to regulate the transmural gradient in length-dependent changes in the time course of contraction of Endo and Epi cardiomyocytes. Our experimental data and their analysis based on mathematical modeling give reason to believe that mechano-calcium-electric feedback plays a critical role in the modulation of electrophysiological and contractile properties of myocytes across the ventricular wall. © Copyright © 2020 Khokhlova, Konovalov, Iribe, Solovyova and Katsnelson.AAAA-A18-118020590031-8Russian Foundation for Basic Research, RFBR: 18-01-00059Russian Science Foundation, RSF: 18-74-10059Funding. Wet experiments were supported by the Russian Science Foundation (#18-74-10059). The development of mouse ventricular cardiomyocyte model was supported by the Russian Foundation for Basic Research (#18-01-00059), IIF UrB RAS theme (AAAA-A18-118020590031-8), and by RF Government Act #211 of March 16, 2013 (agreement 02.A03.21.0006)

Interatomic coulombic decay rate in endohedral complexes

Interatomic coulombic decay (ICD) in van der Waals endohedral complexes was predicted to be anomalously fast. However, the available theoretical calculations of the ICD rates in endohedral complexes only consider the equilibrium geometry, in which the encapsulated atom is located at the centre of the fullerene cage. Here we show analytically that the dominant contribution of the dipole plasmon resonance to ICD does not deviate from its equilibrium geometry value, while contributions of higher multipole plasmons to the ICD can be neglected for most atomic displacements possible for an endohedral complex at room temperature. This is in contrast to the behaviour predicted for ionic endohedral compounds. Our results show that the conclusion of the earlier works on the ultrafast character of the ICD in endohedral complexes holds generally for a wide range of geometries possible under a thermal distribution, rather than only for the equilibrium geometry

Cytoskeleton-dependent changes in the structural organization of reticuloplasmins in Triticum aestivum cells during cold acclimation and treatment with abscisic acid

We studied the effects of the anti-microtubule drug, oryzalin, on the content and spatial organization of reticuloplasmins (Ca2+-binding marker proteins of the endoplasmic reticulum) in winter wheat seedlings after their cold acclimation (3°C, 7 days) and treatment with ABA (30 μM). For identification and visualization of reticuloplasmins, we applied one-dimensional SDS-PAGE with subsequent Western blotting and indirect fluorescent microscopy. We used polyclonal HSP70 and CRH antibodies against BiP and calreticulin (Cal), respectively. On immunoblots, the brightest bands corresponded to polypeptides with mol wts of 58 kD (calreticulin) and 79 kD (BiP). The content of calreticulins in roots was shown to be higher than in leaves. Cold acclimation enhanced, and ABA treatment reduced, the concentration of calreticulins in root cells. Both treatments increased the BiP concentration in roots. Oryzalin (10 μM, treatment for 3 h) did not affect the level of reticuloplasmins in roots of unhardened, cold acclimated, treated with ABA and with a combination of cold and ABA plants. However, both oryzalin and low-temperature treatments resulted in the accumulation of reticuloplasmins in the two spherical structures in the vicinity of the plasmalemma and nuclear envelope. After the combined action of oryzalin and low temperature, the conical sphere of BiP proteins was shifted into the endoplasm and calreticulins appeared in the nuclear matrix. We believe that these changes in the reticuloplasmin localization are related to the rearrangement of the endoplasmic reticulum determined by the cytoskeleton modification. They result in the improved capacity of reticuloplasmins to control Ca2+ behavior and/or to the function as chaperones. The results obtained permit the conclusion that cytoskeletal proteins interact with reticuloplasmins, and this interaction might be involved in the transduction of the external and internal signals

Effects of abscisic acid, low temperature, and plant age on cytoskeleton and phosphorylated proteins

The effects of exogenous abscisic acid (ABA), low temperature, and seedling age on the content of tubulin, actin, and phosphorylated proteins and the structural organization of microtubules (MTs) in cells of different tissues and organs of winter wheat cultivars contrasting in cold hardiness were studied by immunocytochemical methods using monoclonal (against α- and β-tubulin and actin) and polyclonal (phosphothreonine) antibodies. The leaves and roots of five- and nine-day-old seedlings of three cultivars were characterized by unequal proportion of actin/tubulin proteins. ABA decreased the content of the cytoskeleton and the 60-kD phosphorylated proteins, thus promoting a decrease in the number of MTs and occurrence of a less branched network of weakly fluorescent tubulin components in the cells of the root differentiating zone (which is most responsible for the development of cold hardiness in wheat). Although the cold acclimation of plants (3°C, 7 days) did not change the level of tubulin and actin proteins, it evoked the spatial aggregation of MT, leading to formation of a dense network of tubulin cytoskeleton comprised of thick bundles of intensively fluorescent MTs. In the case of a combined action of the studied factors, low temperatures abolished the hormone effect described above, evoking an increase in the content of the cytoskeletal and 60-kD phosphorylated proteins and MT structures. We suggest that the ABA-induced decrease in the levels of proteins and MTs occurs at the initial stages of plant cold acclimation (3°C, 2-3 days). It may be the signal that triggers the processes of low-temperature adaptation. As the duration of cold acclimation increased (3°C, 7 days), the role of ABA in the formation of plant tolerance decreased. Apparently, in this case other hormone-independent mechanisms of frost hardiness development are triggered, in which the role of the cytoskeleton components and cytoskeleton-associated proteins increases

Reorganization of the tubulin and actin cytoskeleton under acclimation and abscisic acid treatment of Triticum aestivum L. plants | Reorganizatsiia tubulinovogo i aktinovogo tsitoskeleta pri zakalivanii rastenii Triticum aestivum L. k kholodu i deistvii abstsizovoi kisloty.

Only scanty and contradictory data are available concerning effects of low temperatures and ABA on the structural organization of microtubules (MTs) and microfilaments (MFs), and no information exists on the interaction of these parameters at cold acclimation of plants. Therefore, in cold acclimate and ABA-treated winter wheat plants, a comparative study was made of the state (localization, orientation, structure) and stability of actin and tubulin cytoskeleton in root cells taken from different zones, using indirect immunofluorescent microscope. The plant cold acclimation caused MT aggregation, the rise of MT and MF fluorescence, and the increase of their stability (a decrease of oryzalin effect) mainly in the root differentiation zone, that may testify to the strengthening of contacts between MTs and MFs. Like the cold acclimation, ABA induced the formation of MT bunches only in meristem and elongation zone cells. However in the zone of differentiation, the hormone stimulated the increase of tubulin structure stability, well correlating with a decrease in MT content, aggregation degree, and immunofluorescence, and, in addition with a complete depolymerization of MFs. Low temperatures removed the hormone effect on the structural organization of tubulin and actin cytoskeleton in the zone of differentiation. It is suggested that MT destruction, the decrease of instable MT populations, and the increase of stable MT populations may slow down growth processes in ABA-treated plants, similarly as in seedlings being on the initial stages of cold acclimation. By the end of this process, the induction of plant growth is determined evidently by the increase in the number of instable, highly labile MT populations, and in the status of MF polymerization