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Статья научная
The aim of this research was to investigate the leaf surface microstructure, pigments spectrum, hormones status and lipids composition of halophytes Polygonum maritimum L. and Euphorbia paralias L. that grow under natural conditions on the dunes of Pomorie Lake, (Bulgaria). It was shown that the existence in saline and dry soils provided among others adaptive mechanisms by specific microstructure of leaf. The adaxial and abaxial surfaces of P. maritimum leaves are covered with a dense layer of cuticle wax, stomata are located on the leaf both sides below the cuticle level. In E. paralias the cuticle is also well developed on the adaxial surface of leaf laminas. The epidermis of the leaf lower side is covered with a less dense cuticle layer formed by large wax crystals. This plant has stoma pores only on the abaxial side of small leaves below the cuticle level and they are surrounded with hump-shaped cuticle constructions. A high amount of carotenoids (as compared with that of chlorophylls) in P. maritimum leaves indicates that these pigments have a light-collecting function and could transfer an additional energy to chlorophylls. The high performance liquid chromatography method has been used to provide a qualitative and quantitative analysis of hormones. It was shown that in leaves of E. paralias and P. maritimum free abscisic (ABA) and conjugated indole-3-acetic (IAA) acids prevailed. A high level of active ABA is correlated with the salt tolerance and ability to survive and grow in stress conditions. A high level of conjugated form of IAA demonstrated that activity of this hormone is limited. The cytokinins qualitative and quantitative analyses demonstrated that in E. paralias leaves zeatin forms dominated, and the level of inactive cytokinins ( cis -zeatin and zeatin-O-glucoside) was much higher than that of active ones ( trans -zeatin and zeatin riboside). P. maritinum leaves contained a significant quantity of isopentenyl forms - isopentenyladenine and isopentenyladenosine, and among zeatin forms, zeatin-O-glucoside prevailed. Studies on the fatty acids content showed that in halophytes the salt resistance mechanism is based on the regulation of plasmatic membrane transport function that involves non-saturated fatty acids. The presence of a large amount of saturated fatty acids provides a decrease of membrane permeability and better resistance against soil salinity.
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The olfactory system regulates acute mountain sickness
Статья научная
OBJECTIVE: Hyperventilation is the first response to hypoxia in high altitude (HA). Our study on rats was designed to establish an integrated hypothesis to include hyperventilation, increased activity of hypothalamic- pituitary-adrenocortical axis (HPA) in response to initial exposure to hypoxia and failure of adaptation to stress in olfactory bulbectomised rats.. METHODS: Albino rats whose olfactory lobes were removed were subjected to hypoxia and hypothermic conditions. Blood and urine samples were collected at various stages to measure biochemical parameters. Rats whose olfactory systems were intact were used as controls. RESULTS: The results suggested that the olfactory system regulated pituitary function and that in rats whose olfactory lobes were removed failed to adapt to the stress created by hypoxia and hypothermia. CONCLUSIONS: Acute Mountain Sickness (AMS) is a type of stress. Normal rats when subjected to stress such as AMS are able to adapt. This adaptation is lost when the olfactory bulbs are removed. It is postulated that serotonin receptors in the hypothalamus, through the splanchnic pathway regulate stress. This mechanism is independent of ACTH - Cortisol feed back system. Perhaps irregular and rapid respiratory rhythm simulates physiological Olfactory Bulbectomy during rapid climbing and AMS manifests as a failure of stress adaptation.
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Статья научная
The aim of the current study was to determine the characteristics of the stress response in endemic species Gmelinoides fasciatus (Stebb., 1899) in comparison with other Baikal amphipods under short term thermal stress. It were shown the changes in activity of antioxidant enzymes, and lactate dehydrogenase correlated with content of lactate under the influence of gradual temperature increase. While the changes of cellular stress - markers content or their activity in other Baikal species occurred beyond the thermal preference zone, the cellular stress - markers content or their activity in G. fasciatus associated with entrance into the thermal preference zone. Thus we concluded that the relict endemic species G. fasciatus has a different stress resistance mechanism to elevated temperature than other Baikal amphipods species.
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Статья научная
Performance of lowland rice grown on anaerobic wetland soil is greatly affected by iron toxicity disorder in Nigeria. Better nutrient management and cultivation of resistant varieties have been recommended as strategy to manage this nutrient disorder. Information on intraspecific lowland NERICA cultivars grown on iron toxic soil augmented with compost is scanty. Therefore, the effect of different rates of compost on growth, dry matter and grain yield of lowland NERICA cultivars grown on iron toxic soil was investigated. A greenhouse experiment comprising of three (two NERICAs and ITA 212) lowland rice cultivars and four varying rates of compost arranged in completely randomized design with six replicates was conducted in greenhouse of Botany Department, University of Ibadan. Data collected on growth and yield parameters were analysed using ANOVA and LSD at P≤ 0.05. Correlation and simple linear regression were used to establish relationship between growth and iron toxicity scores. Results showed that iron toxicity significantly (p≤0.05) reduced growth and yield of lowland rice. Growth and grain yield of NERICA cultivars were significantly better (P ≤0.05) on soil augmented with compost than control. Grain yield was significantly related to the number of leaves affected by iron toxicity. Cultivating lowland NERICA-L-1 on iron toxic soil augmented with 8t ha -1of compost will enhance better growth, dry matter characteristics and increase lowland NERICA grain yield.
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The relationship among metabolic rate of tree shrews (Tupaia belangeri) under cold acclimation
Статья научная
Many small mammals inhabiting cold environments display enhanced capacity for seasonal changes in nonshivering thermogenesis (NST) and thermoregulatory maximum metabolic rate (MMR). However, it is not known how this plasticity remains in a mammal that rarely experiences extreme cold fluctuations. In order to answer this question, we determined body mass (Mb), basal metabolic rate (BMR), NST, and MMR on a tree shrews (Tupaia belangeri), acclimated to cold (5 ºC) conditions. NST was measured as the maximum response of metabolic rate (NSTmax) after injection of norepinephrine (NE) in thermoneutrality minus BMR. Maximum metabolic rate was assessed in animals exposed to enhanced heat-loss atmosphere (He-O2) connected with an open-flow respirometer. Body mass and metabolic variables increased significantly after cold acclimation with respect to control group but to a high extent (BMR, 87.97%; NST, 69.77%; and MMR, 32.35%). However, aerobic scope (MMR/BMR), and calculated shivering thermogenesis (ST) did not significantly change with control group. Our data suggest: 1). The body mass and the capacity of heat production in the cold acclimated group were higher; 2). The increase of BMR and MMR during cold acclimation was the main pattern of heat production in the tree shrews.
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Статья научная
Salinity is one of the most significant abiotic factors affecting growth and yield of cowpea in arid and semi-arid areas of the world. Nineteen cowpea ( Vigna unguiculata ) genotypes were tested during germination and seedling stages of growth at 4 NaCl concentrations (0, 50, 100 and 200mM). The experimental design was completely randomized design (CRD) in factorial combination with three replications. Data analysis was carried out using SAS (version 9.1) statistical software. Germination percentage (GP), seedling shoot and root traits were evaluated. The analyzed data revealed highly significant (p
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The response strategy of maize, pea and broad bean plants to different osmotic potential stress
Статья научная
This investigation was conducted to study the tolerance strategy of maize, broad bean and pea plants to salinity stress with exogenous applications of proline or phenylalanine on seed germination and seedlings growth. From the results obtained, it can be observed that osmotic stress affected adversely the rate of germination in maize, broad bean and pea plants. The excessive inhibition was more prominent at higher concentration of NaCl. The seeds and grains tested were exhibited some differential responses to salinity, in a manner that the inhibitory effect of salinity on seed germination ran in the order, maize higher than broad bean and the later was higher than pea plant. Treatment with proline or phenylalanine (100 ppm) significantly increased these seed germination and seedlings growth characteristics even at lowest salinity level tested.
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Статья научная
In this study, physiological and biochemical responses of ( Pancratium maritimum L.), desert plant which is very widespread on coastal sand dunes to drought were determined. Therefore 28 days (d) old plants were drought stressed by withholding water for 5 and 10 days. The changes in relative growth rate (RGR), relative water content (RWC) lipid peroxidation, and ascorbate-glutathione cycle enzymes activity ((ascorbate peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2) dehydroascorbate reductase (DHAR, EC 1.8.5.1) and monodehydroascorbate reductase (MDAR, EC 1.6.5.4)) were investigated. Relative growth rate, relative water content were both decreased on the 5 and 10d of stress treatment while it was higher on the 10d. MDA content increased on the 10d while it did not change on the 5d. On the other hand, activities of APX, GR, MDAR and DHAR increased on the 5d but were not change on the 10d. These results suggest that ascorbate – glutathione cycle enzymes were efficient to prevent from oxidative damage under short term of drought stress in ( Pancratium maritimum L.) plants.
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The role of alternative respiratory enzymes in photosynthetic plant cells under stress
Статья обзорная
In recent years, it has become clear that for mitochondria in photosynthetic plant cells, the main role of buffer capacity is becoming, allowing to keep under control the balance of ATP production, regulation of the level of pyridine nucleotide reduction, generation of ROS and RNS, as well as optimize the main metabolic flows, which is especially important under stress. Non-conjugated respiration is an important mechanism for achieving stable operation and maximum efficiency of photosynthetic cells. It is actively used in the light and becomes even more important under stress in lighting conditions. The most important part of these non-canonical mitochondrial functions is provided by alternative mitochondrial respiratory enzymes.
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The role of amino acids in improvement in salt tolerance of crop plants
Статья научная
The present work has been performed to study the growth and metabolic activities of maize and broad bean plants which are shown to have a degree of sensitivity to salinity and to determine the role of amino acids proline or phenylalanine in increasing the salt tolerance of theses plants. Dry mass, water content, leaf area and photosynthetic pigment of maize and broad bean plants decreased with increasing salinity. These changes were accompanied with a drop in the contents of soluble sugars, soluble proteins and amino acids. This was accompanied by a marked increase in the proline content. When maize and broad bean plants sprayed with proline or phenylalanine the opposite effect was occurred, saccharides as well as proteins progressively increased at all sanitization levels and proline concentration significantly declined. Salinity significantly increased the sodium content in both shoots and roots of maize and broad bean plants, while a decline in the accumulation of K+, Ca++, Mg++ and P was observed. Amino acids treatments markedly altered the selectivity of Na+, K+, Ca++ and P in both maize and broad bean plants. Spraying with any of either proline or phenylalanine restricted Na+ uptake and enhanced the uptake of K+, K+/Na+ ratio, Ca++ and P selectivity in maize and broad bean plants.
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The role of endophytic microorganisms of medicinal plants in the adaptation of host plants
Статья научная
Cultures of microorganisms were isolated from endosphere of Lake Baikal littoral zone plants: Veronica chamaedrys L., Alchemilla subscrenata Buser, Achillea asiatica Serg., Taraxacum officinale Wigg., Plantago major L. Morphology and biochemical properties of isolated bacteria were studied. For the majority of the endophytic bacterial cultures cellulolitic and proteolytic activity has been shown, which necessary for the effective colonization of plant tissue. For many cultures revealed ability in varying degrees to form a biofilm to improve survival in a vegetative organism. Their potencial role in adaptation of plant-hosts under conditions of climat Baikal region was shown. In particular, 9 of cultures demonstrated ability to act as nitrogen retainer. The vast majority of bacterial cultures did not have phytotoxicity or demonstrated its low level, reflecting and minimum negative effects of them on plant. Moreover, culture with encryption P3, isolated from Plantago major in August, showed a stimulatory effect in experiments on phytotoxicity. This same culture possessed the highest ability to secrete sugars as at +26°С and at +4°С.
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Статья научная
The relationship between energetic parameters and content of stress proteins (alternative oxidase, uncoupling protein and HSP70) in wild grass Elymus sibiricusmitochondria during different stress exposure (cold hardening, cold shock, high-temperature stress, water deficiency and oxidative stress) has been studied. It has been shown that influence of mild stress factors (cold hardening and exogenous 0.5 mM hydrogen peroxide treatment) result in adaptive changes related to the increase of activity alternative oxidase and the increase of content such proteins as alternative oxidase, uncoupling protein and HSP70. The comparative analysis of the function of the cultured and wild plants mitochondria in stress conditions has been produced.
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The role of plant growth promoting extremophilic microbiomes under stressful environments
Статья обзорная
The induction of plant growth promoting microbiomes (PGPM) in agricultural and horticultural field crops considered an environmental friendly biofertilizers, an alternative to chemical fertilization. The PGPM in extreme environments are halophiles, acidophiles, thermophiles, psycrophiles and metal resistant microorganisms are mainly inoculated onto seeds, roots and soil. PGPEM improve plant growth by enhancing the availability of nutrients, the regulation of phytohormones, and by increasing plant tolerance against biotic and abiotic stresses. These PGPM colonize the rhizosphere of plants inducing the accumulation of osmolytes, antioxidants, upregulation or down regulation of stress responsive genes and alteration in root morphology in acquisition of tolerance under adverse environmental conditions. The PGPM have been reported from all three domain archaea, bacteria and eukarya of different groups such as Actinobacteria, Ascomycota, Bacteroidetes, Basidiomycota, Crenarchaeota, Euryarchaeota, Firmicutes and Proteobacteria . The microbes possess the diverse plant growth promoting features and these efficient and potential microbes may be applied as biofertilizers for crops improvements and soil health for sustainable agriculture. In order to survive under the biotic and abiotic stress conditions, these PGPM, have developed adaptive features which permits them to grow optimally under one or more environmental extremes, while poly-extremophiles grow optimally under multiple conditions. In this chapter compile the research progress in PGPM will promise on the development of molecular approaches to increase our knowledge of PGPM and to achieve an integrated management of plant growth promoting extremophiles.
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Статья научная
Expression of gdh1 and gdh2 genes of Arabidopsis thaliana increases in the dark and decreases in the light. The reason of such alteration seems to be a glucose rising in photosynthetic cell in the light, but this hypothesis needs to be confirmed. In this work we investigate the role of glucose and hexokinase 1 in the light-dependent regulation of the gdh1 and gdh2 expression. A comparison of expression profiles of apl3, gdh1, gdh2 genes in presenсe of exogenous sucrose in the dark and in the light has demonstrated that sugar-related repression of gdh1 and gdh2 genes is insufficient to provide the high decrease of their transcripts in the light. Using Arabidopsis mutant gin2-1 with a defect in hxk1 gene we demonstrated that such a decrease is not depended on the regulatory function of hexokinase 1. We presume that light- dependent alterations of gdh1 and gdh2 expression are mediated by some chloroplast-to-nucleus regulatory signals.
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The role of superoxide dismutase in inducing of wheat seedlings tolerance to osmotic shock
Статья научная
Influence of short-term hardening osmotic exposure (immersion in 1 M sucrose solution with subsequent transferring to distilled water for 20 min) on the hydrogen peroxide generation and superoxide dismutase activity in wheat ( Triticum aestivum L., cv. Elegiya) seedlings and their tolerance to osmotic shock were investigated. During the initial 30 min after osmotic exposure, the increasing of hydrogen peroxide amount in roots and shoots (to a lesser extent) was observed, but the resistance of the seedlings and superoxide dismutase (SOD) activity decreased. Sometime later the decrease in hydrogen peroxide amount and the increase of seedlings tolerance to osmotic shock took place. SOD activity increased in 10 min after hardening osmotic exposure. Transient accumulation of hydrogen peroxide induced in this way was suppressed by the treatment of seedlings with sodium diethyldithiocarbamate (DDC), SOD inhibitor. DDC and hydrogen peroxide scavenger dimethylthiourea decreased positive hardening effect of osmotic exposure on the development of seedlings tolerance. It was concluded that SOD providing the generation of signal hydrogen peroxide pool took part in the induction of seedlings tolerance to osmotic shock development caused by preliminary hardening effect.
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Статья научная
Using the real-time polymerase chain reaction method, a change in the level of relative transcription of the SSADH gene in wheat leaves under salt stress conditions was established, correlating with changes in activity. A study of the nucleotide composition of the wheat SSADH gene showed a certain distribution pattern of GATC sequences in the promoter region, which are methylation sites for adenine DNA methyltransferase. Their content is quite high, which may indicate regulation of the expression of this gene by changing the degree of their methylation. Based on the analysis of the nucleotide sequence of this promoter, primers were developed for its amplification and analysis of the adenylate methyl status. A change in the methylation status of adenines in the GATC sites of the succinic semialdehyde dehydrogenase SSADH gene promoter in wheat leaves under salinity was shown.
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Статья научная
The emergence and spread of stress reactions are provided by the blood circulation system. In its turn, the adequacy of blood circulation depends on the hemorheological and vascular mechanisms. The changeability of their properties appears to be the basis of the increasing of stress stages. From the viewpoint of biophysical reactions, any change and movement occur with the expenditure and accumulation of energy. Higher level of adaptation energy waste and secondary level take place, when a small stressor entails a small expenditure. There is a maximum possible rate of adaptive energy consumption and at this maximum the organism cannot cope with any additional stimulus. At the same time adaptive and stress diseases develop. Let’s consider the duration and manifestation of Raynaud's disease from the perspective of adaptation diseases and diseases of the third grade, which appears to be the cause of the double stress effect - cold and emotional- physical and psychic. Total of 97 patients with Raynaud's disease were examined. For a new vision of the problem it was necessary to find out how the streessors of various nature impact the hemoreheological status and vascular resistance. For this purpose all the patients were examined for a resistance index of resistive arteries of the hand and the indices of erythrocyte aggregation and deformability. The patients were divided into four subgroups. The first subgroup - the patients after chilblain, the second subgroup - the patients with psychic strerssor, the third subgroup - the patients with prolonged chronic stress, and the fourth subgroup - the patients without the differentiation of the stressors. According to the obtained results, it is obvious that at cold and emotional stress (I and II subgroups) the hemorheological and vascular parameters are changed. However, this change (hemorheological and vascular) is more pronounced at chronic emotional stress (III subgroup) as compared both to the control and other subgroups. As compared with other subgroups the hemorheological and vascular factors in the IV subgroup differ less from the control. Summarizing the data, it is well seen that the change in hemorheological and vascular properties, so characteristic of Raynaud's disease varies within the limits of the pathological changes in these parameters and depends on the nature and character of the stressor. For an adequate treatment and a final answer the question on Raynaud's disease etiology, as well as on the role of various srtressors in the triggering mechanism and in manifestations of the disease it is necessary to continue a joint clinical-experimental research together with the specialists studying stress.
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Статья научная
Plant growth is impressed by biotic and abiotic stress inversely. There are many reports about proteins change level in salinity stress. Leaves fill up more soluble sugar of glucose, fructose and proline with treatment of salicylic acid. In this research, Salivia officialis seeds planted in pots containing perlite were put in a growth chamber under controlled conditions of 27 ±2 0C and 23 ±2 0temperature, 14h lightness and 10h darkness; NaCl concentration of 0,4,8,12 ds/m and salicylic acid concentration of 0,1,2,4 mM were used in the form of factorial experiment in a complete randomized design (CRD). The results demonstrated that increasing of proline and sugars due to osmotic slope in plants lead to increasing of tolerance against dehydrations of leave content and acceleration of plant developments in stress conditions.
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Статья научная
Soil salinity is a serious environmental problem that has negative effect on plant growth, production and photosynthesis. Fresh and dry plant weights decreases with salinity treatments. The very important role of salicylic acid (SA) in response to different stress and modification and decline damages due to stresses has established in different studies. In this research tomato seeds planted in pots containing perlite in a growth chamber under controlled conditions of 27±2°c and 23±2°c temperature, 16h lightness and 8h darkness respectively, 15 Klux light intensity and 75% humidity; NaCl concentration of 0, 25, 50, 75 and 100 mM and salicylic acid concentration of 0, 0.5, 1 and 1.5 mM were used in the form of factorial experiment in a complete randomized design (CRD). Results show that germination was decreased with salinity increasing. At low levels of salinity, SA leads to decrease in germination and had no effect in high levels of salinity. The length of shoot were not effected by salinity but decrease with increase in SA concentration. Low salinity concentrations led to significant increase in root length and high concentrations dont have significant difference with control. SA also had no effect on it. The highest amount of a, b, c and total chlorophyll and carotenoid was show in 50 mM salinity levels.
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