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Characterization of selected RAB GTPase activating protein (RAB GAP) of Arabidopsis thaliana
Metlička, Jáchym ; Hála, Michal (advisor) ; Eliáš, Marek (referee)
8 ABSTRACT Rab GTPases (Rabs) are the most populous branch of eukaryotic Ras GTPase superfamily. In active GTP-binding conformation, they serve as key instruments in defining transient membrane identity and through various effectors regulate formation, transport, conversion, and fusion of membrane vesicles. This is important for upkeep of compartmentalized structure of eukaryotic cells and for facilitating both endo- and exocytic processes. Rabs are converted into GDP-binding conformation by interactions with Rab GTPase activating proteins (Rab GAPs) that possess ability to significantly speed up weak intrinsic GTP hydrolytic activity of Rabs. Through this process, Rab GAPs can limit scope of the Rabs' activity and lay out spatiotemporal boundaries for varying Rab populations. In this thesis, I tried to characterize a Rab GAP, GAP2, seemingly necessary for standard development of thale cress plants. Besides TBC catalytic domain, GAP2 (product of At2g39280 gene) possesses a C-terminal coiled-coil motif, which was previously found to interact with Rab GTPases. Experiments aiming to complement T-DNA insertion mutant in GAP2, elucidate GAP2 intracellular localization, novel interacting partners, and character of interaction with the Rabs discovered in the pilot study were undertaken. The results suggest that...
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The role of trehalose in mycorrhizal associations
Šoch, Jan ; Ponert, Jan (advisor) ; Hála, Michal (referee)
Mycorrhizal symbiosis is a widely spread phenomenon in nature. A translocation of nutrients occurs between symbionts with disaccharide trehalose playing a key role in the process. However, this saccharide fulfils many important roles in metabolism of fungi and plants. Fungi use trehalose mainly as storage and transport saccharide. On the other hand, trehalose occurs in extremely low amounts in plants where it acts as a signal molecule. Thus it is likely that the saccharide could be used by the fungus to manipulate plant metabolism on a physical interface between symbionts. Trehalose has a similar function in many parasitic interactions. In most cases of mycorrhizal associations trehalose synthesis creates a carbon sink in mycelium which leads to saccharide transfer from the host plant to the fungus. Completely different situation occurs in the types of mycorrhizal symbiosis, where saccharides are translocated from a fungus to a plant. Some plants can utilize trehalose effectively as a sole source of energy. Consequently, the question raises - could such plants gain fungal trehalose on purpose as a source of energy and carbon? This review aims to assess and discuss the mentioned possibilities considering available literature. Key words: mycorrhiza, orchids, parazitism, saccharides, sink, symbiosis,...
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Trehalose metabolism gene manipulations and improving plant abiotic stress tolerance
Hamet, Jaromír ; Lipavská, Helena (advisor) ; Hála, Michal (referee)
In these days, genetic modifications of crops are commonly used in the fight against pests and weeds. More and more often there are also efforts to use genetic modifications to increase tolerance to abiotic stresses that affect worldwide yields much more than biotic ones. Manipulation of trehalose metabolism represents one of the frequently studied options of abiotic stress tolerance enhancement. This work summarizes current knowledge on the protective effects of trehalose in cells and describes signaling functions of trehalose and its metabolic intermediate trehalose-6-phosphate in plants. It also describes current achievements in increasing abiotic stress tolerance through genetic modifications of trehalose metabolism together with accompanying problems. Finally, the potential of this method for future exploitation is discussed.
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Proposal of test equipment/method for quick verification of quality of welded joints
Zejda, Václav ; Hála, Michal (referee) ; Kubíček, Jaroslav (advisor)
This bachelor’s thesis is dealing with the proposal and the choice of the proper method for quick check of weld seams of ball pivot of automobile stabilizers created by the resistance welding method. The first, theoretical part deals with the resistance welding. The second part deals with a description of the production process and testing of the particular component. The last part contains personal proposals and an assessment of the suitability of use of each construction solution of simple mechanical devices for quality checking of the weld seam. The recommended method to use is the Charpy impact test which served as the base for designing the special test device.
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Optimization of a part production made of a structural 20 mm thick steel using laser cutting technology
Šoukal, Hynek ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
The thesis deals with the optimization of process parameters in the oxidative laser cutting of structural 20 mm thick steel with regard to the type of material, the resulting roughness of the cut and the resulting price of the product. In line with the literary study and the Taguchi method, an experiment was developed. The cutting speed, laser performance, cutting gas pressure, and focal position were controlled during the experiment. Sample sets were cut with 7.5" and 10" focusing lens from the TATA STEEL S355MC and SSAB LASER 355 MC steels. According to ČSN EN ISO 9013, the samples were evaluated for roughness. Then micro and macro structures were evaluated, and compare the hardness according to Vickers. In conclusion, technical and economic evaluation was determined.
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Proteomic and functional characterization of PsbO isoforms
Duchoslav, Miloš ; Fischer, Lukáš (advisor) ; Hála, Michal (referee)
PsbO (manganese-stabilizing protein) is the largest extrinsic protein of photosystem II, located on the lumen side of photosystem. It is present in all known oxyphototrophic organisms. PsbO facilitates photosynthetic water splitting, which takes place in an oxygen evolving center (Mn4CaO5 cluster) of photosystem II. This work is focused on PsbO of higher plants and its isoforms, particularly their evolution and functions. Bioinformatic analyses revealed that majority of higher plants express exactly two psbO isoforms. A phylogenetic tree of PsbO sequences has an unusual topology. The two paralogous isoforms do not diverge at the base of the phylogenetic tree, as anticipated, but rather at the end of particular branches, at the level of family or lower taxonomic unit. In this work we propose and discuss several hypotheses concerning evolution of PsbO isoforms. The work further includes detailed analysis and identification of protein spots assigned to PsbO on 2D IEF-SDS PAGE gels of potato thylakoid proteins. We identified predominant version of PsbO isoform in most of the spots. We did not succeed to find any posttranslational modification. We optimized a method of psbO expression in E. coli and subsequent purification, which yielded relatively big amount of properly folded recombinant protein. Analysis of...
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Comparing roughness of cutting edges in cutting of CO2 and YbYAG laser
Podaný, Petr ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
The bachelor thesis deals with the analysis of cutting edge roughness in the process of laser gas cutting using the CO2 laser and laser solid-state cutting using the Yb:YAG laser. The theoretical part is consists of a basic information on industrial lasers and a their methods which use for material cutting. There is part of describing of problems optimum settings cutting parameters and all of roughness measurement. The experimental part was measurement of 20 samples. Samples were made of structural steel DC 01 a S235JR+N, stainless steel X5CrNi18-10+2B and aluminum alloy AlMg3. In the following part is the description of materials and also laser radiation which was used to production of samples. The end of this bachelor thesis is dedicated to evaluation and place in a folder is ČSN EN ISO 9013.
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The study of the influence of process parameters on the roughness of the cut for flame laser cutting of structural carbon steel
Macháč, Patrik ; Hála, Michal (referee) ; Mrňa, Libor (advisor)
This bachelor thesis deals with the cutting of material with laser in an oxidizing environment. It is divided into two parts, theoretical and practical. The theoretical part describes general methods for cutting materials, their advantages and disadvantages, further current industrial lasers are described, as well as the influence of parameters on cutting quality. In the experimental part has been processed the influence of process parameters on the quality of the cut and comparison with ISO 9013. Material used in the practical part is the structural carbon steel called S235JRG2, which was cut in the oxidizing environment. Based on the evaluation of surface, the price of lasser cutting of one meter was selected and then as th best option of settings process parameters for achieving good surface quality was selected. At the conclusions of the thesis there are compared changes in proces parameters and their evaluation
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