Signaling and protection systems in the adaptation of plants to cold

Global climate change increases the urgency of the problem of plant resistance to stress temperatures. Due to temperature instability in winter, as well as the earlier onset of meteorological spring with frosts, the likelihood of lowtemperature damage to plants increases. Adaptive strategies of the different plant species have their own specific features. The review uses mainly the examples of cultivated plants to analyze the current understanding of the mechanisms of cold stress signal perception and transmission to genetic apparatus. Emphasis is placed on the participation of new signal mediators (gasotransmitters) – nitric oxide and hydrogen sulfide – in the formation of plant defense reactions under hypothermia. Data on the role of antioxidant and osmoprotective systems as well as specific proteins in plant adaptation to cold are summarized. The issues of functional interaction between the components of stress-protective systems during cold adaptation are discussed. The opportunities are outlined for the practical use of gasotransmitter donors as agents for plant priming in order to increase their resistance to hypothermia. The possibilities of using indicators of the state of stress-protective systems to search for donors of resistance are also critically analyzed

Three-loop verification of a new algorithm for the calculation of a β\beta-function in supersymmetric theories regularized by higher derivatives for the case of N=1{\cal N}=1 SQED

We verify a recently proposed method for obtaining a $\beta$-function of ${\cal N}=1$ supersymmetric gauge theories regularized by higher derivatives by an explicit calculation. According to this method, a $\beta$-function can be found by calculating specially modified vacuum supergraphs instead of a much larger number of the two-point superdiagrams. The result is produced in the form of a certain integral of double total derivatives with respect to the loop momenta. Here we compare the results obtained for the three-loop $\beta$-function of ${\cal N}=1$ SQED in the general $\xi$-gauge with the help of this method and with the help of the standard calculation. Their coincidence confirms the correctness of the new method and the general argumentation used for its derivation. Also we verify that in the considered approximation the NSVZ relation is valid for the renormalization group functions defined in terms of the bare coupling constant and for the ones defined in terms of the renormalized coupling constant in the HD+MSL scheme, both its sides being gauge-independent.Comment: 19 pages, 8 figures; title changed, minor corrections; the final version to appear in Nuclear Physics

Participation of γ-aminobutyric acid in cell signaling processes and plant adaptation to abiotic stressors

Adaptation of plants to stress factors occurs with the participation of stress phytohormones, signaling network and plant neurotransmitters. Among the latter, in particular, γ-aminobutyric acid (γ-aminobutyric acid – GABA) is a non-proteinogenic four-carbon amino acid found in many prokaryotic and eukaryotic organisms. Its functions in plants have been actively studied only in the past decade. During this period, a lot of information has been accumulated about the protective effect of exogenous GABA on plants of various taxonomic groups under the influence of stress factors of various nature. The first national review is devoted to the analysis and generalization of data on the mechanisms of stress-protective action of GABA in plants. The ways of synthesis and metabolism of GABA in plant cells and the mechanisms of activation of these processes under stressful conditions are described. It is noted that the main way of GABA formation in plants is decarboxylation of glutamate by means of glutamate decarboxy­lase. Possible mechanisms of GABA reception and signal transmission to the genetic apparatus are discussed. Special attention is paid to the analysis of new data on the role of calcium in the activation of GABA synthesis and the realization of its physiological effects. Possible mechanisms of GABA’s influence on the functioning of mitochondria, its role in maintaining redox homeostasis under stressful conditions are discussed. At the same time, data on the increase in the expression of genes encoding the catalytic subunit of NADPH oxidase under the influence of GABA are presented. Functional connections between GABA and nitric oxide as a signaling mediator are considered. The effect of exogenous GABA on the main protective reactions of plants is characte­rized: the state of the antioxidant system, the accumulation of multifunctional low-molecular protectors, the synthesis of dehydrins and chaperones. The data on the phenomeno­logy of the effects of GABA under the main abiotic stresses are presented: the effects of extreme temperatures, drought and salinity on plants. The prospects for the practical use of GABA as a compound that combines the functions of an energy metabolite and a signaling mediator are noted

Авария 1957 года: радиационная обстановка и дозы облучения участников ликвидации аварии на территории промышленной площадки ПО «Маяк»

Purpose: to assess the radiation situation on the industrial site of the PA “Mayak” during the accident in 1957 and the radiation doses of the participants in the liquidation of consequences of this accident. Materials and methods: on the basis of the archival documents analysis, radiation situation data for 1957 – 1960, IDC data and calculated doses of the Mayak workers, as well as supporting organizations personnel and military units involved in the liquidation of the accident consequences and covered by individual monitoring are presented. Results: in 1957 – 1959 about 38,5 thousand people took part in the works on the territory of the PA “Mayak” industrial site for liquidation of consequences of the accident, including persons exposed at the time of the accident: employees of “Mayak”, military and civil builders. Radiation doses from 25 to 30 R received about 10,5 thousand people, while there were single cases of exposure in doses up to 100 R. Conclusion: the collective dose received during the accident and liquidation of its consequences in 1957 was about 820 000 person-R. Collective doses recorded in 1958 and 1959 amounted to 250 000 person-R and 54 000 person-R, respectively.Цель исследования: оценить радиационную обстановку на территории промплощадки ПО «Маяк», сформировавшуюся в результате аварии 1957 г., а также дозовые нагрузки на лиц, принимавших участие в ликвидации последствий этой аварии. Материалы и методы: на основании анализа архивных документов, данных журналов радиационной обстановки за 1957–1960 гг., картотеки индивидуального дозиметрического контроля и проведенных расчетов представлены материалы по измеренным и расчетным дозам облучения как работников ПО «Маяк», так и лиц сторонних организаций и воинских частей, привлеченных к ликвидации последствий аварии и охваченных индивидуальным контролем. Результаты: в работах по ликвидации последствий аварии на территории промышленной площадки ПО «Маяк» в 1957–1959 гг. приняли участие 38,5 тыс. человек, включая лиц, облученных непосредственно в момент аварии, а также работников ПО «Маяк», военных и гражданских строителей, принимавших участие в ликвидации последствий аварии. Дозы облучения от 25 до 30 Р получили около 10,5 тыс. человек, при этом имелись случаи облучения в дозах до 100 Р. Заключение: коллективная доза, полученная во время аварии и при ликвидации ее последствий в 1957–1959 гг., составила ≈820 тыс.чел.-Р, из них 457 тыс. чел.-Р за счет облучения военнослужащих и заключенных 10 лаготделения в момент и первые часы после аварии. Коллективные дозы, зарегистрированные в 4 квартале 1957 г., в 1958 и 1959 гг. у участников ликвидации последствий аварии составили 50 тыс.чел.-Р, 250 тыс.чел.-Р и 54 тыс.чел.-Р соответственно

Reliable designs in foam - biaxial tensile test for estimating the limiting load for polymer foams

A new method for mechanically testing hard foams complements known test procedures. The test results allow the material's inherent strength potential to be exploited more selectively. As a result, critical situations under complex stresses can be predicted

State of enzymatic antioxidative system and heat resistance of wheat plantlets treated by combination of 24-epibrassinolide and NO donor

The influence of 24-epibrassinolide (24-EBL) and nitric oxide donor sodium nitroprusside (SNP) on the state of antioxidative system and heat resistance of wheat (Triticum aestivum L.) plantlets has been investigated. The treatment with 24-EBL (20–200 nM) or with SNP (0.1–2.0 mM) increased the survival of plantlets after 10-min damaging heating at 46 °C in the water thermostat. The cotreatment with 20 nM of 24-EBL and 0.2 mM of SNP caused more essential protective influence in comparison with the treatment by each compound separately. At the same time, joint influence of high concentrations (200 nM of 24-EBL and 2 mM of SNP) reduced the heat resistance of plantlets. Under the influence of 24-EBL and SNP in concentrations that have protective effect, as well as their combinations, the activity of superoxide dismutase (SOD) in roots increased. After damaging heating, the highest value of SOD activity remained in the variant with cotreatment of plantlets with 20 nM of 24-EBL and 0.2 mM of SNP. The activity of catalase and guaiacol peroxidase (GPX) in plantlets roots increased under the influence of various concentrations of SNP and its combinations with 24-EBL. At the same time, 24-EBL alone did not exert the impact on the catalase activity and caused the decrease in GPX activity. The activity of these enzymes decreased in all variants of experiment after heating. The heat stress caused the increase in the content of lipid peroxidation product malonic dialdehyde. The treatment of plantlets with 24-EBL and also its combination with SNP in low concentrations removed this effect, but in high concentrations, on the contrary, increased it. The conclusion was made that intensifying of protective influence of 24-EBL and SNP on wheat plantlets at their combined application in low concentrations is substantially caused by stabilization of pro-/antioxidative balance

2d-tension loading on hard foams and ceramics.

Parts made of hard foams have found wide application in lightweight constructions. The design of these components is based on the strength values gained primarily from tests on specimens under tension, compression, torsion and hydrostatic compression. Beyond this, multi-axial tension tests are required for the validation of an adjusted strength hypothesis [1]. A simple experimental setup for biaxial tension test is developed, which can be realized with a conventional tensile testing machine. The idea of the device is based on the force distribution with girders in three levels [2]. The device allows the introduction of force in the ratios 1/1, 1/2 and 3/4. The simple manner of force distribution requires a specimen in octopus form (Fig. 1). The specimen was designed in such way that the failure develops from the center (test area) to the outside. The radial dependence of the thickness from the test area outwards is C2-steady. The notches between the force insertions are chosen to be ellipses in order to reduce the stress concentrations. A linear elastic behaviour of the foams is assumed for the dimensioning of the specimen. The geometry of the specimen is optimized for the worst case with the elastic Poisson ratio equal to 0 and evaluated using the normal stress hypothesis. The maximal stress occurring in the notches are minimized by the geometry of the specimen. The dimensions of the specimen are adapted to the commercially produced foam blocks. The experimental results from tension and balanced biaxial tension are valuable additional strength information. The experiment can be used to test many different types of materials like glass, ceramics, aerated concrete, sintered materials, granular materials etc