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Adaptation to adverse osmotic conditions as a tool for evolutionary enginnering of bacteria
Drotárová, Lenka ; Nováčková, Ivana (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the application of osmotic stress as a tool for evolutionary engineering of PHA producing bacterial strains. The aim of this thesis is to evaluate a bacterial adaptation to hypoosmotic environment, as an engineering tool in order to increase the production of PHA. The theoretical part focuses on the evolutionary engineering principle, methods of the strategy and the effect of physical factors on microorganism. The aim of experimental part was to performed an adaptive evolutionary experiment with the bacterial strain Halomonas halophila CCM 3662. Reduced osmotic pressure was used as a stressing factor during the serial cultivation. In order to generate PHA producing mutant strains, each passage was characterized using spectrophotometric and gravimetric method and by GC-FID. It was found that after the long-term cultivation, the mutant strain HH35, cultivated in 35 g/l NaCl, was associated with the highest biomass and PHB concentration. The 15th and 30th passages, along with the wild type strain H. halophila were subjected to further cell-robustness analysis with the application of hyper- and hypoosmotic shock. The stress response, viability of cells and morphological changes were analyzed using FC and TGA methods. Isolated polymers were characterized using FTIR analysis.
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Stomata opening and closure regulation in respect to osmotic stress
Hofírková, Miroslava ; Hála, Michal (advisor) ; Lhotáková, Zuzana (referee)
Stomata are structures located in higher plants' epidermis and they regulate mainly CO2 intake and transpiration. The stomata are important for plants' protection against excessive water loss during osmotic stress. This thesis is a literary research summarizing stomatal movements regulation during osmotic stress. The main part of the thesis is focused on stomatal closure with the help of ABA under water deficiency conditions. There are the ABA synthesis, transport and its impact on stomata described in individual chapters. The ABA early signalling pathway and an ionic channel regulation are described in detail on the basis of the published data. The second part of the thesis is about second messengers produced by ABA and their impact on stomatal movement regulation. The special attention is paid to hydrogen peroxide and nitric oxide and their contribution to stomatal closure. The last part is about passive (hydraulic) stomatal closure. Keywords: plants, stomata, osmotic stress, ABA, stomatal movements
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Cuticle, its formation and importance in resistance of plants to abiotic stress
Litkeiová, Veronika ; Hála, Michal (advisor) ; Tylová, Edita (referee)
Plants are daily exposed to stress, biotic or abiotic. Both of these types can be divided into several subgroups. This work is focused on plant cuticle, its formation and function in respect to abiotic stress resistance. The main factors, mentioned in this work, are drought, heat, UV radiation, excessive salinity or ozone exposure. The individual chapters focus on the composition, biosynthesis and changes in the build-up construction caused by certain types of stressors. A significant part is also devoted to cutin and cuticular waxes, which play an important role in plant protection and whose structure is also affected by abiotic stress. Phytohormones, especially abscisis acid, which had its application here, are also not omitted. In the final phase of the thesis, cuticular mutants are mentioned in connection with abiotic stress types illustrating the role and the importance of the cuticle layer. Key words: plants, cuticle, osmotic stress, abscisic acid, cutin, waxes
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Physiological mechanisms of abiotic stress tolerance in Sorghum bicolor
Kratochvíl, Jan ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Current agriculture is facing a serious challenge of decreasing precipitation and irregular occurrence of drought periods including their unfavorable distribution during the vegetation season. This leads to growing interest in planting highly drought-resistant crops like sorghum. In comparison with other crops, sorghum excels in low water demand, though exhibits high susceptibility to low temperatures, which hampers its spread to new regions. Surprisingly, there is not enough information about the nature of sorghum's reaction to cold exposure. The aim of this diploma thesis was to describe reactions of young sorghum plants exposed to cold stress, low water availability and their combination and to verify the possibility of plant hardening through previous low-stress load. The special focus was paid to changes in carbohydrate metabolism, which plays generally very important role in plant defense reactions. The other analyzed physiological traits were leaf tissue osmotic potential, proline content and basic morphometric characteristics. Experimental design consisted of pot experiments conducted in growth chambers and the experiments performed under controlled conditions in vitro, using two sorghum genotypes "Ruzrok" and "01Z1800012". Both genotypes exhibited similar response to stress treatment....
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Water use efficiency (WUE), its definition and importance in plant resistance against osmotic stress
Jedlička, Tomáš ; Hála, Michal (advisor) ; Lhotáková, Zuzana (referee)
Water is one of the main limiting factors of plant growth. Availability of water on our planet is reduced, and if we add fast-growing human population, we have a problem brewing. Scientists from all around the world, especially those from arid regions, are facing a big problem, which is an attempt to make the most efficient use of water by plants. If this problem should be solved, we need to understand the issue of Water Use Efficiency (WUE). This paper attempts to summarize the current knowledge related to the issue of WUE, mainly focused on anatomical and physiological parameters control of WUE, which is focused primarily on the issue of evapotranspiration. Another part focuses on clarifying the issue of WUE at the gene level and the related biotech opportunities. At the end of the work are discussed possibilities of increasing WUE using irrigation techniques.
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Water use efficiency (WUE), its definition and importance in plant resistance against osmotic stress
Jedlička, Tomáš ; Hála, Michal (advisor) ; Lhotáková, Zuzana (referee)
Water is one of the main limiting factors of plant growth. Availability of water on our planet is decreasing, and if we add fast-growing human population, we have a problem growing. Scientists from all around the world, especially those from arid regions, are facing a big problem, which is an attempt to make the most efficient use of water by plants. If this problem should be solved, we need to understand the issue of Water Use Efficiency (WUE). This paper attempts to summarize the current knowledge related to the issue of WUE, mainly focused on anatomical and physiological parameters control of WUE, which is focused primarily on the issue of evapotranspiration. Another part focuses on clarifying the issue of WUE at the gene level and the related biotech opportunities. At the end of the work are discussed possibilities of increasing WUE using irrigation techniques. Key words: water use efficiency, evaporation, transpiration, stoma, stomatal density, abscisic acid, ERECTA
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Role of the yxkO gene of Bacillus subtilis in responce to environmental stress.
Petrovová, Miroslava ; Lichá, Irena (advisor) ; Nešvera, Jan (referee)
ROLE OF THE YXKO GENE OF BACILLUS SUBTILIS IN RESPONCE TO ENVIRONMENTAL STRESS Abstract Mutation of the yxkO gene, which encodes a putative ribokinase and belongs to the σB general stress response regulon, leads to reduced salt tolerance under potassium limitation in Bacillus subtilis. The biological function of the yxkO gene has not been determined yet, but it may be involved in the high affinity potassium uptake system, which has been described in Escherichia coli in contrast to Bacillus subtilis. Our goal was to describe another features of a mutant in the yxkO gene and to try to propose the role of this gene. Using the integration vector pMutin4, we prepared a Bacillus subtilis strain MP2 with a yxkO gene inactivation. The MP2 strain displays limited growth in a rich medium and it is a sensitive strain to tetracycline. Furthermore, this strain is unable to form endospores and the cells are longer, which indicates a septum formation defect. We accomplished a 2-D protein gel analysis to compare expression profiles of the MP2 strain and the 1A680 standard strain after salt and ethanol stress. The MP2 strain shows changes in productions of some energy metabolism enzymes and flagellin protein. We conclude that yxkO is a regulatory gene, whose product has a pleiotropic effect on many of cell functions.
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