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Leaf structural changes induced by tropospheric ozone.
Češpírová, Zdeňka ; Lhotáková, Zuzana (advisor) ; Hála, Michal (referee)
Tropospheric ozone is an important pollutant formed by the photochemical reactions of ultraviolet radiation and nitrogenous. Recently, its concentration in the air is increasing due to the promoting climate change and antropogenic activities, mainly because of combustion of the fossil fuels. The ozone is highly reactive molecule degrading to the reactive oxygen species having negative effects on the leaf physiological functions and structure. Ozone penetrates the leaf through the stomata, thereafter it reacts with the cells and their singular compartments. The products formed due to ozone degradation are able to cause the disintegration of plasma membranes and other oxidative damage, for example accumulation of plastoglobuli inside the chloroplasts, changes in the shape of chloroplasts, mitochondria or peroxisomes. At the macroscopic level the visible lesions, chloroses and necroses are observed. In addition, the faster senescence of leaves is observed under the effect of ozone. The main aim of present thesis is to review knowledge of the ozone-induced changes in the leaf structure beginning on the cell structure level and ending at the whole plant body level and to explain physiological mechanisms leading to these damages. Key words: ozone, oxidative stress, leaf structure, mesophyll, reactive...
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Techno-economical comparison of the fusing and flame method of laser cutting of steel sheets with a solid-state laser
Vojteková, Lucia ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
The aim of diploma thesis is a comparison of flame and fusion laser cutting of thin metal sheets for ACO Industries k. s. company, where the experimental part was also realized. After consultation with company, the thesis was extended by data samples, which were cut by compressed air for comparison with other two gases. The optimization design of cutting parameters was created by Taguchi method. Afterwards the surface roughness of samples was measured. Based on Ra and Rz5 parameters, the samples were classified to classes based on their accuracy according to ISO 9013 standard. According to results the fusion method of laser cutting is more suitable method, especially for its good quality of cutting edge, which is not affected by the oxidic layer. Fusion method uses cutting speed two times higher than the flame method, which leads to decrease of time and financial consumption of the process despite of its higher hourly rate. In case of laser cutting of material by compressed air the quality of cut is insufficient in comparison with fusion or flame cutting method.
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Utilization of trehalose in orchids: evolution of trehalase genes
Šoch, Jan ; Ponert, Jan (advisor) ; Hála, Michal (referee)
All orchid species studied so far have been shown to participate in orchideoid mycorrhizal symbiosis. Morover, this symbiosis is absolutely vital component of their life cycle. Exchange of nutrients occurs between symbionts where the fungi provides the orchid with energy and carbon supply at least in its early developmental stages. This study focuses on the possible role of trehalose in this transfer. In vitro experiments have showed in five species from three different subfamilies of Orchidaceae family that they can utilize trehalose comparably with sucrose and glucose. Thus, the ability of trehalose utilization seems to be conserved among orchids. Trehalase enzyme activity was localized histochemically in orchid mycorrhizas. The activity strongly colocalized with colonized tissue supporting a hypothesis that trehalose transfer occurs in this site and is mediated by trehalase. Using bioinformatic methods, trehalase gene duplications were identified in many taxons of Embryophyta including three orchid species. Interestingly, highest number of trehalase gene copies was identified in genome of orchid Dactylorhiza majalis. Trehalose utilization, high trehalase activity in mycorrhizas and trehalase gene duplications in some orchids together indicate that trehalose transfer in orchid myccorhizas...
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Renewal of selected vehicle in Volšatrans company
Hála, Michal ; Rathouský, Bedřich (advisor) ; Volšička, Miroslav (referee)
This bachelor thesis deals with the current state of Volšatrans transport company fleet, captures and evaluates its overall condition and subsequently recommends a proposal for its replacement. The change is made on the basis of the multi-criteria decision-making method, namely the TOPSIS method, the result of which is the output showing particular proposals for the replacement of the vehicle. This output may be in practice used by Volšatrans as a recommendation for selection of a suitable vehicle variant on the basis of their requirements.
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Effectors of RAB GTPases and their role in plant secretion
Růžičková, Martina ; Hála, Michal (advisor) ; Motyka, Václav (referee) ; Klíma, Petr (referee)
Rab GTPases are small signaling molecules that play an important role in vesicle trafficking in eukaryotic cells. Correct signaling through small GTPases allows orchestration of vesicle transport among cellular organelles and also to the cell wall providing cell wall material for cell growth and elongation. Engagement of Rab GTPases in the regulation of endomembrane trafficking is one of the evolutionary conserved aspects of secretion regulation. The network of Rab GTPases interaction includes also various downstream effectors. One of them is the exocyst complex involved in vesicle docking at the plasma membrane. It is a complex composed of eight different subunits (Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70 and Exo84). Exocyst was discovered as Sec4p Rab GTPase effector in yeast and also data from animal models describe the Sec15 exocyst subunit as the Rab-interacting partner, but data from plants are missing. On the other hand, numerous studies identified exocyst role in tip growth of pollen tube and root hairs, seed coat formation, cell plate and cell wall formation, hypocotyl elongation, and importantly also PIN auxin efflux carriers recycling and polar auxin transport. There are two paralogues of SEC15 in the Arabidopsis genome, SEC15a and SEC15b, the previous one already shown to be...
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Saccharides as an integral part of plant antioxidative system
Štěpánová, Nikola ; Lipavská, Helena (advisor) ; Hála, Michal (referee)
The formation of reactive oxygen species (ROS) in plants is inevitable part of aerobic cellular metabolism, during which ROS are generated as by-products of basal metabolic pathways. ROS participate in many processes in plants. If the ROS are at normal level, they serve as signal molecules. Under stress, however, the ROS level in plants increases. High ROS accumulation can cause severe oxidative damage of cellular components, but simultaneously it activates other signal pathways controlling defence against oxidative stress. Plants protect themselves against increased level of ROS in different ways. Either they try to prevent increased level of ROS, or they try to detoxify them. Plants utilize for detoxification two efficient antioxidative systems - enzymatic and non-enzymatic ones. The main goal of this work is to put saccharides into context of plant non-enzymatic antioxidative system and summarize saccharides-based ROS scavenging mechanisms, which have been invented so far. Research on mechanisms of ROS scavenging is highly important, because oxidative damage through excessive production of ROS is considered to be significant cause of productivity losses in agricultural crops. These losses are likely to increase as a result of increased stress burden connected with expected climatic changes. Key...
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Mechanisms of natural resistance of quinoa to abiotic stresses
Cíza, Marek ; Lipavská, Helena (advisor) ; Hála, Michal (referee)
Quinoa is traditionally grown crop originating from areas adjacent to Andean Mountains in South America, where it is grown by local native population for over 5000 years. Its extraordinal resistance to abiotic stresses as salinity, drought or frost, along with quite exceptional nutritional qualities of the seed, earned it the designation "supercrop" and the year 2013 was even announced by the FAO organization as the International Year of Quinoa. The main aim of this thesis is to identify the main mechanisms responsible for quinoa resistance to frost, salinity and drought. Marginally, this work also focuses on reaction of quinoa against an attack of most common fungal pathogen and also on different sensitivity of quinoa varieties towards the lenght of photoperiods, which are two important factors in expanding the cultivation of quinoa outside the original area.
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Characterization of the exocyst complex SEC15 subunit in A. thaliana
Aldorfová, Klára ; Hála, Michal (advisor) ; Hafidh, Said (referee)
The final step of secretion termed exocytosis is mediated by the exocyst complex. The exocyst is an evolutionary conserved protein complex that tethers secretory vesicle to the target membrane and consists of eight subunits: Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo84, and Exo70. Sec15 exocyst subunit was previously shown to connect the rest of the exocyst complex with a secretory vesicle in yeast, mammals and fruit fly via interaction with Rab GTPase and GEF of Rab GTPase. Here, I show that plant SEC15B potentially functions in evolutionary conserved manner. First, two mutant lines of Arabidopsis thaliana sec15b mutant were tested in characteristics typical for other exocyst mutants. Although some characteristics reach certain level of plasticity, both sec15b-1 and sec15b-2 show similar tendencies, which are mostly consistent with defects with other mutants in exocyst subunits. sec15b-1 has been determined as a stronger allele that is defective in formation of seed coat, elongation of etiolated hypocotyl, growth of stem and primary root, establishment of axillary branches and lateral roots, diameter of rosette and, unexpectedly, growth of pollen tubes. Phenotype of sec15b-1 was rescued by insertion of SEC15B gene under SEC15B promotor. Second, complementation test showed that SEC15B and SEC15A are...
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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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