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Promoter-terminator interactions in eukaryotic RNA polymerase II transcription
Petr, Martin ; Hozák, Pavel (advisor) ; Vaňková Hausnerová, Viola (referee)
Gene loops are chromatin structures formed by juxtaposition of distal genomic regions. Since these regions are often involved in transcription cycle control, gene loops therefore provide another mechanism of regulation of gene expression. This thesis summarizes recent findings about gene loops, focusing specifically on loops formed by interactions between promoter and terminator regions of genes transcribed by the eukaryotic RNA polymerase II. Different cases of gene loops discovered in several yeast genes, the mammalian BRCA1 tumor suppressor and the HIV-1 integrated provirus are described, including mechanisms that possibly lead to the formation of these structures. Since gene loops and interactions between promoter and terminator in yeast have been linked to the transcriptional memory, their involvement in this phenomenon is discussed. Finally, as BRCA1 and HIV-1 are directly linked to serious human diseases, the potential significance of alterations of gene loops in the development of various pathological conditions is presented. Keywords: gene loops, chromatin loops, chromatin conformation, transcriptional memory, transcription, gene expression, regulation
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Biodegradation of 17alfa-ethinylestradiol by enzymes of ligninolytic fungi
Přenosilová, Lenka ; Stiborová, Marie (advisor) ; Černá, Věra (referee)
This work is aimed at the study of the effect of 17α-ethinylestradiol (EE2) on the production and characteristics of ligninolytic enzymes (laccase, Mn-dependent peroxidase and lignin peroxidase) in I. lacteus, T. versicolor, P. chrysosporium and P. ostreatus cultures grown on two types of liquid media. Enzyme activity production in fungal cultures was affected by the composition of culture medium. In the case of P. chrysosporium, the addition of EE2 to the complex- medium cultures led to a MnP activity stimulation and simultaneously LiP production was partially repressed in these cultures. In the mineral MM medium, no effect of EE2 on enzyme production by P. chrysosporium was observed. In EE2 treated MM cultures of P. ostreatus lower MnP activities were found when compared to biotic controls. In the case of T. versicolor cultures, the addition of EE2 to the complex medium caused laccase and LiP stimulation in the cultures. In the MM medium, however, only laccase production was affected by EE2. I. lacteus MnP production was partially repressed by EE2 in MM medium. In contrast to that, significantly higher MnP activities were detected in complex- medium I. lacteus cultures after the treatment with EE2. Further EE2 degradation by the fungal cultures was studied. The highest degradation effeciency was...
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Effect of zearalenone on reproductive parameters and the expression of selected genes in mice.
Dvořáková, Eva ; Pěknicová, Jana (advisor) ; Nedvídek, Josef (referee)
A number of chemicals may have a negative impact on the environment and wildlife. Endocrine disruptors (EDs), which can mimic estrogen, interfere with natural hormones in organism and can have a negative effect on the reproductive system. Such substances include zearalenone (ZEA) - mycotoxin, produced by the fungi Fusarium. Despite the non-steriodal structure of its molecule, ZEA and its derivates possess potent estrogenic activity. The influence of ZEA on reproductive parameters and changes in expression of selected genes were tested in the outbred line of mice. This study showed significant effects of ZEA on number of reproductive performances. This effect was observed at lower examined dose, to which are humans normally exposed, and at higher doses, both showed changes in the tested parameters.
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The role of Src family kinases in RNA processing
Gemperle, Jakub ; Rösel, Daniel (advisor) ; Mácha, Jaroslav (referee)
Until now, a lot of information have been obtained about the role of Src family kinases in the cytoplasm or at the plasma membrane and their interactions with growth factor receptors or focal adhesion complexes. Their functional importance at the perinuclear membrane, or even inside the nucleus, however, has not been well characterized. This work, using available information, pointed at the fact that Src family kinases can be found in the nucleus. This opens a new field of Src kinases action, such as in RNA metabolism, considering that it has been assumed that their activity is limited to the cytoplasmic compartment. This work summarizes the current knowledge that hints to Src family kinases dependent network of regulation of RNA metabolism; Src family kinases have pleiotropic effects not only on the RNA binding proteins, but also on the remodeling of chromatin structure. These kinases affect by direct interactions with other proteins transport, splicing or RNA stability and gene expression. This summary suggests that Src family kinases could regulate RNA metabolism on many levels.
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Factors interacting with bacterial RNA polymerase
Sudzinová, Petra ; Krásný, Libor (advisor) ; Fišer, Radovan (referee)
The bacterial cell must be able to rapidly change its gene expression to survive unstable external conditions. Transcription is the key level that affects gene expression. The pivotal enzyme of transcription is RNA polymerase (RNAP). Activity of RNAP is tightly regulated by transcription factors (TFs). These factors affect RNAP in different ways. This work presents an overview of various proteins and others factors, description of their effects on transcription and also mechanisms of their actions. TFs could be divided according to various criteria. In this work, TFs are divided according to how they interact with RNAP: TFs interacting only with RNAP; TFs binding simultaneously DNA and RNAP; TFs interacting with RNA and RNAP. This work presents a comprehensive overview of various TFs that are involved in the bacterial cell's reprogramming of gene expression that is required to withstand the changes in the environment.
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Cis and trans elements in plant response to drought (with a particular focus on photosynthetic genes)
Panchártek, Daniel ; Holá, Dana (advisor) ; Feketová, Zuzana (referee)
Abiotic stresses, such as drought, high salinity and cold can strongly affect plant development and growth. Cis and trans elements are one of the options how plants regulate their own metabolism in those cases. That's the way how the expression of many target genes is induced. The products of these genes function not only in stress tolerance but also in general stress response. Many transcription factors and regulatory proteins (trans elements) are involved in these adaptions; those often interact with specific sequences in gene promoters (cis elements). Recenly, a progress has been made in analyzing the signal paths and complex cascades of gene expression regulation, although a little is still known about this regulation during drought conditions. Some of these target genes code products participating in photosyntesis and the regulation of their expression can significantly affect this process. This essay briefly describes main cis and trans elements of plant response to drought (with a particular focus on the regulation of photosyntetic genes). Keywords: drought, gene expression, cis-element, transcription factor, abcisic acid, photosyntesis, promoter.
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Laccase activity profiling in Trametes versicolor cultures degrading endocrine-disrupting compound Delor 103
Plačková, Martina ; Svobodová, Kateřina (advisor) ; Mikušová, Gabriela (referee)
In this work endocrine disrupting potential of Delor 103, a commercial mixture of PCB congeners, was studied along with its effect on production of laccase by the ligninolytic fungus Trametes versicolor. Using a gene-reporter yeast assay for evaluation of hormonal activity Delor 103 showed an androgenic activity with an EC50 value of 2.29. 10-2 mg/l. Chlorbenzoic acids, Delor 103 potential metabolites resulting from microbial degradation, displayed on the other hand an estrogenic activity, indicating possible changes in hormonal activity of Delor 103 during its microbial degradation. The addition of Delor 103 to mineral medium T. versicolor cultures resulted in an up to 257times higher laccase activities detected in fungal cultures. Delor 103 induced enzymes showed different pI values from those of control cultures. In a complex malt-extract glucose medium (MEG) the stimulation effect of Delor 103 was kept down. Further, the production of laccase and synthesis of different pI forms depended strongly on the growth phase of fungal cultures. Exponencially growing cultures of T. versicolor were able to produce up to 7 different pI forms of laccase in responce to Delor 103 whereas stationary cultures produced only 4 enzyme forms with higher pI values. Stimulation of laccase activities in T. versicolor,...
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delta subunit of bacterial RNA pol and its role in regulation of gene expression in B. subtilis
Dvořáček, Lukáš ; Krásný, Libor (advisor) ; Vopálenský, Václav (referee)
Delta subunit of bacterial RNA pol and its role in regulation of gene expression in B. subtilis. In this work I focus on regulation of eubacterial gene expression. First, I describe recent knowledge about a key stage of gene expression - transcription, focusing on regulation of trancription iniciation via small effector molecules (guanosine tetraphosphate, initiating nucleoside triphosphate) that are important for the regulation of ribosomal RNA. Second, in the experimental part of my work, I focus on the role of the _ protein, a subunit of RNA polymarase in gram positive bacteria, in transcription iniciation and its effects on regulation of RNA polymerase by the concentration of initiating nucleoside triphosphates.
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The role of microRNAs in chronic lymphocytic leukemia
Moravec, Martin ; Macůrková, Marie (referee) ; Hájek, Miroslav (advisor)
2 Abstract MicroRNAs (miRs, miRNAs) are recently discovered molecules (19-25 nucleotides long) that regulate gene expression at post-transcriptional level by either blocking protein synthesis or mRNA degradation. As a part of gene silencing mechanism, miRNAs are involved in cellular processes, such as apoptosis, cell proliferation, development and viral defence. miRNAs have been intensely studied in connection to disease pathogenesis. Chronic lymphocytic leukemia (CLL) is the most common leukemia in Western countries affecting mostly elderly people. In my work I focus on explanation of miRNA functions and their contributions to chronic lymphocytic leukemia (CLL). I describe previously published data about miRNA-15, miRNA-16, miRNA-143, miRNA-145 and miRNA-155 in connection to this disease. Based on recent reports, I also discuss the potential role of miRNA-326 in CLL pathogenesis.
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