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Due to their sessile life style plants have to cope with a variety of unfavourable environmental conditions. Extracellular stimuli are perceived by specific sensors and receptors and are transmitted within the cell by various signal transduction pathways to trigger appropriate responses. The mitogen-activated protein (MAP) kinase cascades are well-conserved signalling pathway modules found in all eukaryotes. Activated MAP kinases phosphorylate an array of substrate proteins. Phosphorylation results in altered substrate activities that mediate a wide range of responses, including changes in gene expression. The genome of the model plant Arabidopsis thaliana contains genes encoding 20 mitogen-activated protein kinases and 10 MAPK kinases. In plants MAP kinases play a central role in environmental stress signalling; however, our knowledge mainly comes from results on three MAP kinases and their immediate upstream activators. Further studies on additional members of the plant MAP kinase repertoire together with the identification of downstream substrates and connections to specific upstream signal receptors are required to elucidate their specific functions within environmental stress signalling networks. Understanding the mechanisms of specificity in signal flow is indispensable for engineering improved crops with modified MAP kinase signalling for agricultural purposes.
In the hydrogeologically closed Carpathian Basin subsurface waters have particular importance in the salinization/alkalization processes. In the poorly-drained low-lying areas the capillary flow transports high amounts of water soluble salts from the shallow, „stagnant” groundwater with high salt concentration and unfavourable sodium-carbonate(bicarbonate) type ion composition to the overlying soil horizons. Due to the strongly alkaline soil solution, the Ca and Mg salts (mostly carbonates and bicarbonates) are not soluble and Na + became absolutely predominant in the migrating soil solution which leads to high ESP even at relatively low salt concentration. High Na + saturation of heavy-textured soils with high amount of expanding clay minerals results in unfavourable physical-hydrophysical properties and extreme moisture regime of these soils, which are their main ecological constrains and the limiting factors of their fertility, productivity and agricultural utility. The simultaneous hazard of waterlogging or overmoistening, and drought sensitivity in extensive lowland areas, sometimes in the same places within a short period, necessitates a precise, “double function” soil moisture control against their harmful ecological/economical/social consequences. Most of the environmental constrains (including salinity/alkalinity/sodicity) can be efficiently controlled: prevented, eliminated, or - at least - moderated. But this needs permanent care and proper actions: adequate soil and water conservation practices based on a comprehensive soil/land degradation assessment. It includes continuous registration of facts and changes (monitoring); exact and quantitative knowledge on the existing soil processes, their influencing factors and mechanisms.
Yeast protein sequence-based homology search for glutathione (GSH) metabolic enzymes and GSH transporters demonstrated that Aspergillus nidulans has a robust GSH uptake and metabolic system with several paralogous genes. In wet laboratory experiments, two key genes of GSH metabolism, gcsA, and glrA, encoding γ-l-glutamyl-l-cysteine synthetase and glutathione reductase, respectively, were deleted. The gene gcsA was essential, and the ΔgcsA mutant required GSH supplementation at considerably higher concentration than the Saccharomyces cerevisiae gsh1 mutant (8–10 mmol l−1 vs. 0.5 μmol l−1). In addition to some functions known previously, both genes were important in the germination of conidiospores, and both gene deletion strains required the addition of extra GSH to reach wild-type germination rates in liquid cultures. Nevertheless, the supplementation of cultures with 10 mmol l−1 GSH was toxic for the control and ΔglrA strains especially during vegetative growth, which should be considered in future development of high GSH-producer fungal strains. Importantly, the ΔglrA strain was characterized by increased sensitivity toward a wide spectrum of osmotic, cell wall integrity and antimycotic stress conditions in addition to previously reported temperature and oxidative stress sensitivities. These novel phenotypes underline the distinguished functions of GSH and GSH metabolic enzymes in the stress responses of fungi.
Abstract
It is well-documented that harsh environmental conditions influence appetite and food choice. However, the experience of environmental harshness is complex and shaped by several underlying dimensions, notably threats to one's social support, economic prospects, and physical safety. Here, we examined the differential effects of these three dimensions of environmental harshness on desire for specific food items. We first showed 564 participants images of 30 food items. Next, they rated how much they desired each item. The participants were then randomly assigned to a condition where they read one of six scenario stories that described someone's current living conditions. Each scenario story emphasized one of the three dimensions (social support, economic prospects, physical safety), with two levels (safe, harsh). Following this, the participants once again rated how desirable each food item was. The results showed that exposure to cues of low social support and high physical threat reduce the desire to eat, whereas cues of economic harshness had little effect. Further analysis revealed a significant interaction between energy level of different foods and perceived threat to physical safety. These findings are important in helping to understand how current environmental conditions influence changes in appetite and desire for different kinds of food items.
97 101 Hoffmann, A. A., Woods, R. E. (2003) Associating environmental stress with developmental stability: problems and patterns. In: M. Polak (ed.) Developmental Instability: Causes
Lyme disease [ 22 ]. Biofilms are an aggregation of planktonic bacteria that attach on biotic and abiotic surfaces to form a three-dimensional architecture to withstand various environmental stressors [ 23 ]. The presence of a protective surface matrix
, ensuring safety against environmental stressors (sheer forces, heat and drying damage), components of the immune system (phagocytes, complement) and noxious chemical agents (disinfectants and antimicrobials) [ 53 , 54 ]. The EPS matrix alters the the
, K. , 1985 . Physiological determination of impact of environmental stress on the activity of microbial biomass . Environm. Pollut. Ser. A. 38 . 283 – 294 . K OCSIS
The changes of cell surface hydrophilicity in Bacillus subtilis were analyzed in response to oxygen-limitation, heat shock, salt stress, pH-shock, phosphate- and carbon-limitation. Although cell surface hydrophilicity varied during growth phases, an increase of surface hydrophilicity was observed under several of these stress conditions. An observed drop in intracellular GTP and/or ATP may be an element of the signal transduction pathway leading to an increase in surface hydrophilicity in response to environmental stresses. Attachment of cells to soil particles under salt stress conditions is strongly influenced by the degS/degU two-component system, which thereby provides a mechanism for the bacteria to escape from the hostile environment.
Abstract
The balance of essential elements in organisms can be changed by environmental stresses. A small fresh water fish, the medaka, was irradiated with X-rays (total dose: 17 Gy, which is not a lethal dose for this fish). Essential elements in the liver, gall bladder, kidney, spleen, heart and brain of the fish were measured by the particle induced X-ray emission (PIXE) method and compared with those of a control fish. Various changes in the elemental balance shift were observed. The PIXE method can analyze many elements in a small sample simultaneously, and so the changes in elemental content induced by irradiation were readily determined.
