National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Functional characterization of Alba-family genes in Arabidopsis thaliana
Kočová, Helena ; Honys, David (advisor) ; Fischer, Lukáš (referee)
(anglicky) Alba-family proteins were identified in Archaea and Eucarya and are classified among the oldest and the most conserved nucleic acid-binding proteins. The binding preferences and roles differ among certain evolution clades. In Crenarchaea they represent chromatin-binding proteins, while their role in RNA metabolism is suggested in Euryarchaea and Eukaryotes. ALBA proteins are well characterized in human, where they play a role in the RNAse P/MRP complex and in unicellular parasites, such as Plasmodium and Trypanosoma, where an involvement in the life cycle regulation is confirmed. In plants, their role is not yet well understood. The aim of this thesis is to increase a knowledge about the Alba-family proteins in the model plant Arabidopsis thaliana. Based on a minimal changes to development and reproduction in single mutants and high sequence similarity, a functional redundancy of the proteins was assumed. For better understanding of the ALBA proteins function, three smaller members of the family were edited by the same metod. The obtained triple mutant showed delay in flowering. ALBA dimer formation was confirmed in many organisms. BiFC method was used to determine Arabidopsis ALBA homodimerization. The data analysis showed potential homodimerization in most of them.
Study of RNAi mechanisms in tobacco BY-2 cell line and potato plants
Tyč, Dimitrij ; Fischer, Lukáš (advisor) ; Kovařík, Aleš (referee) ; Moravec, Tomáš (referee)
Knowledge of the processes of RNA interference, the regulation of gene expression by small RNAs (sRNAs), has grown at an unprecedented rate over the last 30 years. Some of the findings were literally revolutionary, as they revealed events that overturned many long-held notions. Many phenomena have been shown to be highly conserved and common to organisms of different species, but others are specific to certain lineages or have not yet been fully explored. There is also a lack of knowledge about the interconnection of numerous pathways - for example between silencing at the transcriptional (TGS, leading to the promoter methylation) and post-transcriptional levels (PTGS, affecting mRNA stability or translation). The present work summarizes the findings of two published and two unpublished works and attempts to describe some of the less known sites of RNA interference using various plant model organisms. Research on Solanum tuberosum transgenic lines has revealed the ability of 5-azacytidine to restore the expression of transcriptionally silenced transgenes at the whole plant level. De novo regeneration from leaves of such plants can lead to re-silencing of reactivated transgenes and thus serves as a selection method to exclude lines prone to spontaneous silencing. The nature of changes in the...
Parent-of-origin contributions to gene expression during sexual plant reproduction
Pitoňak, Oliver ; Honys, David (advisor) ; Fischer, Lukáš (referee)
Sexual reproduction in flowering plants is fundamental to seed formation. After fertilization, the embryo is enclosed and develops in a seed together with a triploid tissue - the endosperm. In animals, early embryogenesis is well-known to be controlled by maternal RNA and proteins deposited in the ovule before fertilization. Even after the activation of zygotic genome, paternal and maternal genome do not play interchangeable roles. A few genes affecting embryo growth and development are transcribed either from maternally or paternally inherited alleles only. Such genes are example of the well-known phenomenon of gene imprinting. In plants, imprinting is well documented in the endosperm. The role of parent-of-origin contributions to gene expression has been studied less extensively in embryo. The aim of this work is to critically assess current knowledge of parent-of-origin contributions to embryo development in different plant species.
Role of sequence context in DNA methylation
Polák, Jan ; Fischer, Lukáš (advisor) ; Širl, Marek (referee)
Cytosine methylation of DNA is a pivotal epigenetic mark, which contributes to the regulation of the gene expresion, silencing of transposable elements, and co-defines chromatine state. There are three cytosine contexts: CG, CHG and CHH (where H stands for C, A, or T). Arabidopsis thaliana (and plants in general) has an arsenal of molecular mechanisms capable of cytosine methylation in all of its contexts. That said, there are two tasks at hand: maintaining of pre-existing methylation and if need be, creating new methylated spots. The actual process of maintaining of the methylation depends on the cytosine context. Methylation of symmetrical contexts of CG and CHG can utilize the information about the methylation pattern from the second DNA strand. The aymmetrical context of CHH, and also CHG need to look for this information elsewhere: in the methylation of the lysine 9 of H3 histone. This creates a self-reinforcing loop and a crosstalk between two epigenetic mechanisms. Maintaince of methylation of CHH is also navigated by small RNA complementary to the locus in question. This mechanism of enzyme navigating by RNA is also used in establishing a new methylated site for all of the contexts. CG methylation is most prevalent in both heterochromatine and euchromatine. It also has a special functions...
Modulation of BELL transcription factors balance as a tool for tuberisation strengthening in selected potato cultivars
Zounková, Andrea ; Mašková, Petra (advisor) ; Fischer, Lukáš (referee)
Potato (Solanum tuberosum) is the third most important crop in terms of human consumption. Hence understanding regulatory mechanisms controlling tuber initiation is significant not only from a theoretical but also practical point of view. Tuberization of S. tuberosum is a complex morphogenic process regulated by both, environmental conditions and inner plant status. Environmental conditions regulating the onset of tuberization have been known for a long time, but the molecular basis of tuber initiation has only recently been discovered, in particular using wild subspecies S. tuberosum subsp. andigena. BELL transcription factors are among the important components of the regulatory signalling network. The aim of this study was to modulate balance between the BELL transcription factors that induce and repress tuberization towards strengthening of tuber induction using two cultivars of Solanum tuberosum subsp. tuberosum, cv. Kamýk, resp. cv. Korela. To achieve this, transgenic lines carrying construct containing a part of coding sequence StBEL11, resp. StBEL29 in antisense orientation (AS) under control of constitutive promoters and lines carrying complete sequences of StBEL5 and StPTB6 genes under control of their native promoters were derived. We used the StBEL11 and StBEL29 AS constructs with the aim to...
Tuber induction in spontaneously tuberizing potato line: the role of saccharides and mobile transcripts
Stupecká, Lenka ; Mašková, Petra (advisor) ; Fischer, Lukáš (referee)
Potato is one of the most important agricultural crops and there is an attempt to increase and improve yields of tubers, among other things, by elucidation of the mechanisms that regulate the process of tuber induction. Potato tuberization is a morphogenetic process in which the tubers are formed from the underground parts of the stem - stolons. The correct timing of this process is controlled by a complex regulatory network and influenced by many internal and external factors. Under favourable conditions, an inductive signal is generated in the leaves and it is transported to the stolon by a "phloem information superhighway" driven by carbohydrates flow. The signal triggers cell division, expansion, and changes in the cell growth orientation in the stolon. The development of tubers is influenced by number of biochemical and morphological processes driven by a regulatory network of genes that are expressed in different parts of plants. This work was focused on Solanum tuberosum, Lada cultivar and its derived D69 mutant line with lacking isoform of manganese-stabilizing protein (MSP), which is so far the only dissimilarity identified under all tested conditions. I aimed to map the processes related to the production of carbohydrates in leaves (photosynthetic characteristics - rate of photosynthesis...
Study of the function of the hybrid proline-rich protein family
Dvořáková, Lenka ; Fischer, Lukáš (advisor) ; Vágner, Martin (referee) ; Havel, Ladislav (referee)
Lenka Dvořáková SUI'^,ÍARYoF TřE PH.D. TFDSIS 4. CONCLUSIONS Ancestral HyPRP evolved probably from a lipid transfer protein (LTP) relative that had acquired a sequence encoding a long proline-rich N-terminal domain. The origin of HyPRPs may be one of the evolutionary innovationsof seedplants. Specific sequence is not probably important for formation of the functional 8 CM domain of HyPRPs with exception of eight conserved cysteine residues.which stabilize the tertiary structureof the domain. HyPRPs with long proline-rich N-terminal domains are relatively well-conserved and probably evolutionary more original. Proteins with aýpical N-terminal domains (very short. glycine-rich) evolved apparently relatively recently and independentlyin differentplant speciespossibly by means of shortening, loss or re€uTangements of the ancestral longer proline-rich domains. Glycine-rich domains could originate from proline-rich ones by way of inversion in the coding sequence.This mechanismcould have greatimpact in evolution of cell wall proteins in general, becausethey are often rich eitherin prolineor glycine. N-terminal domains of angiosperm C-type HyPRPs remained relatively well conserved (long and hydrophobic), while the rest of angiosperm HyPRPs has been undergoing rapid and continuous diversification. However, in the...
Inducible RNAi against essential genes of nitrogen metabolism as a tool for control of GM plants
Kobercová, Eliška ; Fischer, Lukáš (advisor) ; Tylová, Edita (referee)
Uncontrolled spreading of genetically modified (GM) plants is one of the main concerns about their cultivation. Inducible RNA interference against an essential gene could be a tool for control of GM plants. After spraying with a chemical inducer, the essential gene will be silenced so the treated GM plant will die. For testing this strategy we chose two key enzymes of nitrogen metabolism, glutamate synthase (GOGAT) and glutamine synthetase (GS). GS processes ammonium ions into glutamine, then GOGAT transfers the amide group from glutamine to 2-oxoglutarate to form two glutamates. GS/GOGAT cycle is the main pathway for assimilation of ammonium ions, which could be toxic to plants in a higher concentration. Disruption of ammonium assimilation during photorespiration causes a strong inhibition of photosynthesis. The aim of this work was to describe the effects of silencing GOGAT and GS genes in Arabidopsis thaliana. To induce silencing, RNAi hairpin constructs under a control of constitutive or estradiol-inducible promoter were prepared. In selected independent transformants with the inducible hairpin against GOGAT, chlorosis and reduced growth were observed after the estradiol treatment in in vitro conditions. However, the spraying with estradiol was tricky, at the whole plant level, the induction of...

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1 Fischer, Ladislav
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