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Long term sublethal stress in colonies of Saccharomyces cerevisiae deleted in WHI3
Krampotová, Ester ; Schierová, Michaela (advisor) ; Dušková, Michala (referee)
The yeast species Saccharomyces cerevisiae is a suitable model for studying many biological processes, including adaptation to stress conditions. Over the past 40 years, multiple signaling pathways have been uncovered to play an important role in the response to acute stress induced by high temperature, osmotic stress, or high concentrations of metals in S. cerevisiae. The effect of sublethal dose of stressor is rather neglected. The advantage of the WHI3 deletion strain used in this work is its sensitivity to the presence of stressor in the solid medium not only by reducing the growth rate but also by changing the colony morphology. The Whi3 protein stimulates not only flocculin Flo11 production but also the activity of the general transcription factors Msn2 and Msn4. The diploma project aimed to determine whether changes in the expression of genes coding for stress proteins induced by sublethal doses of the stressor were dependent on the genotype WHI3, YAP6, and MPT5. Transcription factor Yap6 and RNA binding protein Mpt5 are both involved in stress response and cause repression of FLO11. Their levels depend on Whi3. To induce mild stress, low concentrations of NaCl and CdSO4 have been applied to colonies for 4 and 6 days. Their genotype varied in the WHI3, YAP6, and MPT5 genes. Our experiments...
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Plant exocyst dependent secretory pathway and iron nutrition
Batík, Adam ; Žárský, Viktor (advisor) ; Vaňková, Radomíra (referee)
Previous results from our lab suggested possible phenotypic deviation of a double T-DNA knock- out mutant of an EXOCYST subunit EXO70E2 and vacuolar transmembrane protein LAZ1H1 upon iron starvation. To confirm these preliminary results, single mutants were obtained, with EXO70E2 knock-out mutant being produced here using CRISPR/Cas9 technology. Result did not confirm the previous findings in neither of the mutants tested (exo70e2, laz1h1, exo70e2/laz1h1 and exo70h4). This discrepancy is attributed to improper iron starvation protocol and different storage age of seeds used in the previously conducted experiments. Coumarins are synthetized and secreted from roots during iron starvation; protocol for their visualization was adopted and WT compared with mutants. No phenotypic deviations were observed in mutants. Pharmacological treatments of iron starved WT plants using BFA, wortmannin and concanamycin A did not suggest that endomembrane vesicle trafficking affect accumulation or secretion of coumarins. Previously published susceptibility of T-DNA knock-out mutant of EXO70E2 to drought stress was tested using CRISPR/Cas9 mutant produced here, the reported susceptibility was not confirmed. Upregulation of EXO70E2 mRNA upon UV exposure reported in eFP browser was also tested and not confirmed under...
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Effect of cold on humans from the perspective of physiology and ecology
Chvojková, Anna ; Hora, Martin (advisor) ; Oplt, Pavla Alexia (referee)
This bachelor thesis deals with the issue of cold and its effect on humans. The aim of the thesis is to compare how much different factors such as body proportions, amount of brown adipose tissue (BAT), age or sex influence the physiological response to cold. According to the available literature, the physiological response to cold is mainly dependent on body proportions and the amount of BAT, while factors such as age and sex are not as significantly reflected in the response. The second aim is to inspect whether ecogeographic rules also apply to human populations with a special focus on one Arctic population - the European Sami. Sami have, as predicted by ecogeographic rules, a broad trunk and short limbs, which limits heat loss. The last goal of the thesis is to clarify the possible use of cold exposure in healthcare and sports physiotherapy. Cold therapy could help with the treatment of inflammatory diseases, obesity, depression, or muscle recovery. However, further application of cold therapy in medical practice requires a thorough study of the mechanisms by which cold affects specific diseases and the definition of optimal conditions under which cold therapy is effective.
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Origin and regulation of intraepithelial CD4+CD8a+ T-cells induction by Segmented Filamentous Bacteria
Pacáková, Iva ; Dobeš, Jan (advisor) ; Štěpánek, Ondřej (referee)
Segmented filamentous bacteria (SFB) are member of mice intestinal microbiota with very unique life strategy involving tight interaction with the host's intestinal epithelium. This association with intestinal epithelial cells (IECs) induces strong immune response characterized by Th17-mediated immune response. However, recent findings revealed that SFB induce also huge accumulation of CD4+ intraepithelial lymphocytes (IELs) by the upregulation of MHCII expression on IECs in an IFN-dependent manner. Likewise to SFB, Lactobacillus reuteri was recently found to have a similar capacity of IELs induction. In contrast to SFB, L.reuteri induces IELs through the activation of the Aryl hydrocarbon receptor (AhR) by its ligands, which originate from the metabolism of tryptophan amino acid. Moreover, L.reuteri cannot induce IELs by itself and needs a complex microbiota for this induction. However, if these two bacteria can cooperate in the induction of IELs remains unknown. This thesis focuses on the interaction of SFB and L.reuteri in the context of IELs induction and investigates the contribution of each bacteria to the IELs phenotype. Data presented in my thesis indicate that SFB induce accumulation of IELs, however, interaction of SFB and L.reuteri induce full cytotoxic activation and vesicle secretion...
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Heat transfer in solar energy equipment
Hylas, Martin ; Jegla, Zdeněk (referee) ; Babička Fialová, Dominika (advisor)
Photovoltaic panels are an efficient device for converting solar energy when exposed to high solar radiation intensity, which is, however, associated with a high ambient temperature. The high operating temperature of a photovoltaic panel has a negative effect on the efficiency and lifetime of the device. The first part of this thesis presents the current state of the art in the field of active and passive cooling methods for photovoltaic panels. The main metrics for evaluating the effectiveness of cooling systems are the cooling rate and the power gain of the photovoltaic module. The research shows that significant reduction of temperature effects can be achieved by support systems, but based on the experimental work to date there is no unified view on the applicability of the cooling devices in practice. Investment and operating costs are a significant barrier to the use of these systems by the general public. A possible solution to efficiently generate electricity and utilise otherwise wasted heat is to combine the functions of photovoltaic panels and solar thermal collectors into hybrid photovoltaic-thermal collectors. The tubular distribution system is an integral part of these installations. From a design point of view, these are simple systems, naturally subject to uneven distribution of the working medium, which results in a decrease in the efficiency of the entire device. In the second part of the thesis, the functionality of analytical models to predict the distribution of the working medium in a K-type distribution system is verified. The results of the comparison of predicted data with experimentally measured values show that the predictive ability of the analytical models is strongly dependent on the method of determining the value of hydraulic resistance (local losses).
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Solid stick friction modifiers for rail transport
Ondák, Andrej ; Hajžman, Michal (referee) ; Galas, Radovan (advisor)
The present work deals with solid friction modifiers, which are substances that have the task of reducing the contact friction of the wheels of railroad vehicles, thus reducing wear and noise emission. In order to maximise the efficiency of the system, material consumption must be kept to a minimum. When solid friction modifiers are applied, there is a danger of isolation of the contact, which is an undesirable effect regarding track systems. At the moment, both the positives and the negatives of the technology are known, but without a deeper connection to application parameters. Therefore, the experimental part of the thesis is focused on determining the influence of application on the performance of rigid friction modifiers. The thesis also focuses on the effect of the working frequency of the track systems on the contact impedance and on the consumption of the compositions themselves. As a result of the research, the application parameters strongly influence the performance of the solid compositions. It was also observed that the friction modifier tends to adhere to the surface of the body, to which it is applied and thus there is no transfer to the other body. On the contrary, it was found that the contact impedance is independent of the working frequency. The development part of the thesis is dedicated to the design of a solid composition applicator and a device for measuring the impedance and consumption.
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Plasma diagnostics for the therapeutic applications
Kletzander, Lukáš ; Slavíček, Pavel (referee) ; Krčma, František (advisor)
Plasma, an ionized gas, is often regarded as the fourth state of matter. It has many useful applications, from arc welding to plasma displays. An emerging application of low-temperature plasma is in medicine, too. Reactive species generated in plasma discharges are the source of its usefulness in sterilization and supporting would healing. The detailed characterization of plasma is a key point before its real application in medicine. Thus, this is the main goal of this thesis. The subject of this thesis was the characterization of three new experimental applicators generating microwave plasma at 2,45 GHz in argon. The angle of argon flow into the applicator was the differentiating factor, the three versions have had angles of 0, 15 and 30 degrees. This angle affected the spatial distribution of the generated reactive species, as well as the discharge length and its stability. The reactive species, which included nitric oxide, oxygen radical and hydroxyl radical, were analyzed using optical emission spectroscopy. The diagnostic was done along the discharge axis for different mass flows of argon and at different power. In addition, photos of the discharges at selected powers and argon flows were taken. The lengths of the discharges were measured from the images. It was found out that the intensity of spectral transitions of the reactive species is dependent on the aforementioned parameters – mass flow of argon and supplied power. The intensity of these particles’ radiation related to their concentrations generally increased as more power was supplied to the applicator. The intensity subsequently decreased with increasing gas flow. The active region of the discharge also decreased as gas flow was increased. The length of the discharges was also dependent on supplied power and gas flow. The three versions of the applicators have shown differences – a maximum and a subsequent decrease in length with increasing gas flow were observed, the rate of the decrease being different for the three versions. The average length of the discharge was also different for the three applicators.
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Influence of some medicinal fungi and other prebiotics on growth and metabolism of probiotic bacteria
Husová, Martina ; Bendová, Agáta (referee) ; Márová, Ivana (advisor)
The bachelor thesis deals with the influence of medicinal mushrooms and other prebiotics on the growth and biological activity of probiotic bacteria. Selected genera of lactic acid bacteria Bifidobacterium and Lactobacillus can produce antimicrobial substances bacteriocins and their production depends on cultivation conditions and available nutrient sources. The theoretical review describes and characterizes probiotic bacteria, their metabolism and importance for human health. Similarly, the theoretical section focuses on prebiotics and their selected representatives, which are four species of medicinal fungi, the microscopic algae Chlorella, resistant starch, the cell biomass of the yeast Saccharomyces cerevisiae and dietary supplements such as inulin and psyllium. In the experimental part, extracts were prepared from these prebiotics by three different methods - boiling, macerating and hydrolysis. The obtained extracts were characterized in terms of macronutrient content such as carbohydrates and proteins. Based on the growth of four species of lactic acid bacteria cultured in standard medium and their production of antimicrobial substances, a strain of B. bifidum was selected for cultivation in the presence of prebiotic extracts. After determining the increase in probiotic biomass in the prebiotic extracts, the cultures were centrifuged, and the protein content of the bacterial supernatant was determined. The lactic acid content of the lyophilized probiotic extracts was determined by high-performance liquid chromatography, and finally, the antimicrobial activity was determined by broth dilution method and resazurin viability assay. The results of the antimicrobial tests were compared with the antimicrobial activity of lactic acid at the same concentration as that contained in the probiotic extracts. For the highest macronutrient content of the prebiotic extracts, extraction by boiling was the most suitable method. For insoluble polysaccharides such as resistant starch, hydrolysis might be a better option, but this requires subsequent treatment of the extract to provide suitable conditions for cultivation. The boiled extracts were the best for the growth of probiotic bacteria as well as their production of antimicrobial substances. The highest concentrations of protein and lactic acid were measured in these samples. The likely presence of bacteriocins was confirmed in all culture types. Almost all probiotic extracts showed antimicrobial activity against Staphylococcus epidermidis and Escherichia coli. The likely presence of bacteriocins was confirmed by the broth dilution method, for example in extracts containing chlorella algae or S. cerevisiae yeast, because these extracts were antimicrobial at lower concentrations than the lactic acid present.
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Gelation of waterglasses depending on their composition
Otřísalová, Pavlína ; Kalina, Lukáš (referee) ; Bílek, Vlastimil (advisor)
This bachelor thesis studies how are gelation of sodium and potassium silicates (water glass) influenced by their composition. The main goal of the thesis was to investigate the effect of silicate concentration, molar ratio, and alkaline ions on the gelation time. Qualitative analysis of obtained gels was also performed. The thesis includes literature research in the field of chemistry of silicate sols and gels. In the experimental part were prepared samples of both sodium and potassium silicates with silicate concentrations of 15 M and molar ratios of 0,53,0. Gelation was induced by adding calcium ions. Gelation time was measured using rheological oscillation tests (time sweep) and visual method. Qualitative analysis of the gels was performed using rheological oscillation tests (amplitude and frequency sweep) and visual method. Three significant trends were observed: 1) NaVS samples always had shorter gelation time than KVS samples 2) the higher the silicate concentration the higher the gelation time 3) gelation time of samples with molar ration of 2 was most influenced by silicate concentration. It was also observed that the formation of gel network was promoted in systems with 1) higher molar ratios 2) higher silicate concentrations 3) presence of K+ ions. Gels with molar ratios 2 were significantly weaker than those with ratio of 2,5 or 3,0.
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Use of molecular techniques for study of thermophilles
Dvořáková, Dominika ; Kouřilová, Xenie (referee) ; Buchtíková, Iva (advisor)
Polyhydroxyalkanoates are microbial storage polymers that represent a green alternative to petrochemical plastics. However, their high production cost limits wider industrial utilization. Use of waste materials as a substrate and/or utilization of extremophilic organisms is an option to reduce production costs. The strain of thermophilic bacteria Aneurinibacillus appears to be a promising producer because of its ability to synthesize wide range of non traditional copolymers. In addition, PHA synthesis is independent of nutrient limitation, which was the subject of this study. Experiments were focused on the expression of genes involved in PHA synthesis in the bacterium Aneurinibacillus sp. AFn2 on different types of production media. The presence of selected genes was verified using classical PCR. After that the cultivation experiments were performed on mineral and complex media to simulate environments with different nutrient availability. Biomass concentration was determined gravimetrically from the samples collected in time during the growth curve measurement. PHA content was measured simultaneously using gas chromatography. Finally, the expression of the studied genes was analysed by RTqPCR. Significant differences were observed in the transcription of individual genes depending on the media type and time. The results confirmed the ability of Aneurinibacillussp.AFn2 to produce PHA independently on nutrient limitation, however, the production rate and cell filling depended on the media type. This fact may be related to the different course of expressed genes involved in PHA synthesis. A higher percentual yield of P(3HB) in cells were observed in complex media along with an increasing trend in the overall gene expression. On the other hand, in mineral medium, the transcription of individual genes only decreased after initial strong expression, and the cell filling of P(3HB) was also lower. The findings lead to understanding not only the expression of selected genes but also the overall synthesis of PHA. At the same time, it offers the way to optimize production with the aim of reducing cost and expanding their market applications.
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