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RNA interference in plants
Čermák, Vojtěch ; Fischer, Lukáš (advisor) ; Kulich, Ivan (referee)
The process of RNA interference allows cells to regulate functions of their genes. This process is usually initiated by the presence of double-stranded RNA within a cell. Such double-stranded RNA is diced by a specific protein called Dicer into duplexes of small RNAs, usually 20-25 nucleotides long. Single-stranded small RNAs, released from the duplexes, are the heart of RNA interference and they can be categorize into several groups according to their biogenesis. There are two groups of small RNAs in plants: miRNA and siRNA. Small RNAs can associate with a protein called Argonaut and guide it to the target molecule on the bases of sequence complementarity. The Argonaut-small RNA complex can act on itself or it can interact with other proteins in a wide spectrum of processes. The complex can slice the target mRNA (which can be handled by the sole Argonaut and small RNA), it can suppress translation or it can direct chromatin modifications. The phenomena of RNA interference can be found in almost all Eukaryotes where it can serve many functions, for example it can control cell differentiation, participate in stress responses, direct changes in chromatin and defend the organism against viruses. A diverse set of operating modes of RNA interference can be found in plants, which we are only at the...
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Hydrophilic polymers-based delivery systems for the transport and controlled release of siRNA
Blažková, Jana ; Laga, Richard (advisor) ; Vopálenský, Václav (referee)
Therapeutics based on siRNA represent a promising hope for the treatment of many congenital and acquired disorders. This method is based on posttranscriptional silencing of pathological gene or set of genes (RNAi process), which are responsible for the actual cause of the disease. Access is therefore based on the assumption of treatment options for the disease at the point of origin of the defect intervention at the molecular level, which is different from the conventional, so-called symptomatic therapy, which focuses only on the treatment or suppression of symptoms. Despite rapidly increasing understanding of gene function and cause a number of genetic diseases, the expansion of siRNA therapeutics limited the development of efficient and safe transport systems (vectors). In order to ensure efficient transport of siRNA in vivo conditions, the vectors must sufficiently reduce the size of the siRNA, protect it against degradation during transport, and release in the cytoplasm of the target cell. For this purpose they were developed sophisticated transport systems based on viral and non-viral origin. This diploma thesis is focused on the preparation of new transport systems, siRNA-based synthetic hydrophilic polymers, such as non-viral vectors. For in vitro testing the effectiveness during transport of siRNA...
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Reverse genetics in anaerobic protists
Stojanovová, Darja ; Tachezy, Jan (advisor) ; Doležal, Pavel (referee)
This work is focused on reverese genetics of anaerobic protists, mainly T. vaginalis, G. intestinalis and E. histolytica and deals with techniques and experimental procedures of genome manipulation in these parasites. Both DNA and RNA can be manipulated and the gene function can be disclosed using methods of reverse genetics. The knowledge gained is useful in many ways. For example, using these techniques crucial aspects of biology of parasitic prostist are studied, providing basis for potential development of new drugs. Utilization of such methods also helps to understand the cellular and metabolic pathways and mechanisms, that could be very diverse or reduced in protists. The methods of reverse genetics that result in permanent and inheritable changes in DNA are, for instance, homologous recombination or DNA integration. There is also a transcriptional gene silencing (TGS) technique to stop gene expression even though the coding DNA remains unchanged. TGS could be realized by several mechanisms, for example by RNA interference. RNA interference pathway, commonly known as posttranscriptional gene silencing mechanism, causes the breakage of mRNA or stops its translation. Other techniques of gene silencing involve, e.g., the expression of antisense RNA, oligonucleotudes and ribozymes.
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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...
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Hydrophilic polymers-based delivery systems for the transport and controlled release of siRNA
Blažková, Jana ; Laga, Richard (advisor) ; Vopálenský, Václav (referee)
Therapeutics based on siRNA represent a promising hope for the treatment of many congenital and acquired disorders. This method is based on posttranscriptional silencing of pathological gene or set of genes (RNAi process), which are responsible for the actual cause of the disease. Access is therefore based on the assumption of treatment options for the disease at the point of origin of the defect intervention at the molecular level, which is different from the conventional, so-called symptomatic therapy, which focuses only on the treatment or suppression of symptoms. Despite rapidly increasing understanding of gene function and cause a number of genetic diseases, the expansion of siRNA therapeutics limited the development of efficient and safe transport systems (vectors). In order to ensure efficient transport of siRNA in vivo conditions, the vectors must sufficiently reduce the size of the siRNA, protect it against degradation during transport, and release in the cytoplasm of the target cell. For this purpose they were developed sophisticated transport systems based on viral and non-viral origin. This diploma thesis is focused on the preparation of new transport systems, siRNA-based synthetic hydrophilic polymers, such as non-viral vectors. For in vitro testing the effectiveness during transport of siRNA...
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Reverse genetics in anaerobic protists
Stojanovová, Darja ; Tachezy, Jan (advisor) ; Doležal, Pavel (referee)
This work is focused on reverese genetics of anaerobic protists, mainly T. vaginalis, G. intestinalis and E. histolytica and deals with techniques and experimental procedures of genome manipulation in these parasites. Both DNA and RNA can be manipulated and the gene function can be disclosed using methods of reverse genetics. The knowledge gained is useful in many ways. For example, using these techniques crucial aspects of biology of parasitic prostist are studied, providing basis for potential development of new drugs. Utilization of such methods also helps to understand the cellular and metabolic pathways and mechanisms, that could be very diverse or reduced in protists. The methods of reverse genetics that result in permanent and inheritable changes in DNA are, for instance, homologous recombination or DNA integration. There is also a transcriptional gene silencing (TGS) technique to stop gene expression even though the coding DNA remains unchanged. TGS could be realized by several mechanisms, for example by RNA interference. RNA interference pathway, commonly known as posttranscriptional gene silencing mechanism, causes the breakage of mRNA or stops its translation. Other techniques of gene silencing involve, e.g., the expression of antisense RNA, oligonucleotudes and ribozymes.
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Yeast gene silencing.
Tarabová, Eva ; Kuthan, Martin (advisor) ; Schierová, Michaela (referee)
Each cell contains a complete copy of the entire genetic equipment of the organism. However not all genes are expresed, cells are differentiated in higher eukaryots and only certain proteins are transcribed in each cell. This is possible thanks to a gene silencing, that is stable throughout the whole cell cycle and epigeneticaly inherited from one generation to another. Gene silencing serves also in the maintainance of the chromosomal integrity, it is connected with the right progression of the cell division. It even enables mating type switching and ensures right cells' identity in yeasts. The basis is compact and a higher-ordered structure of chromatin called heterochromatin. The mechanism is common to many various organisms, although the proteins, which ensure silencing, are different.
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RNA interference in plants
Čermák, Vojtěch ; Kulich, Ivan (referee) ; Fischer, Lukáš (advisor)
The process of RNA interference allows cells to regulate functions of their genes. This process is usually initiated by the presence of double-stranded RNA within a cell. Such double-stranded RNA is diced by a specific protein called Dicer into duplexes of small RNAs, usually 20-25 nucleotides long. Single-stranded small RNAs, released from the duplexes, are the heart of RNA interference and they can be categorize into several groups according to their biogenesis. There are two groups of small RNAs in plants: miRNA and siRNA. Small RNAs can associate with a protein called Argonaut and guide it to the target molecule on the bases of sequence complementarity. The Argonaut-small RNA complex can act on itself or it can interact with other proteins in a wide spectrum of processes. The complex can slice the target mRNA (which can be handled by the sole Argonaut and small RNA), it can suppress translation or it can direct chromatin modifications. The phenomena of RNA interference can be found in almost all Eukaryotes where it can serve many functions, for example it can control cell differentiation, participate in stress responses, direct changes in chromatin and defend the organism against viruses. A diverse set of operating modes of RNA interference can be found in plants, which we are only at the...
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