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Silencing of Transposable Elements in Plants and Implications for Rationalised Transgene Design
Tobiáš, Andrej ; Fischer, Lukáš (advisor) ; Moravec, Tomáš (referee)
(English) Transposable elements (TEs) are integral parts of all plant genomes. Their ability to change their position (transpose) or copy to a new position and induce mutations within these genomes has driven evolution for billions of years. Despite its importance, unrestrained transposition can lead to irreversible genomic damage. Therefore, plants have evolved special silencing mechanisms to regulate transposition and "silence" TEs. This allows plants to harness the mutagenic potential of TEs, tame their new insertions, and thus potentially acquire genomic novelties. Silencing mechanisms operate mostly at the epigenetic/transcriptional level, where they induce methylation on target DNA or histones. This accounts for RNA-dependent DNA methylation pathways (RdDMs). Additionally, they operate at the post-transcriptional level, where they degrade target mRNA through a pathway known as post-transcriptional gene silencing (PTGS). These silencing mechanisms have also become proficient in recognizing both natural and artificial transgenes. Recognition and subsequent silencing of transgenes diminishes the efficiency of transgenesis and, thus, successful production of genetically modified organisms (GMOs). Extensive research into these silencing pathways and TEs can lead to a better understanding of what...
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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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PCR detection of genetically modified soybean in food and feed
CHADIMOVÁ, Nikola
Genetically modified organisms which genetic equipment has been specifically targeted of have been acquiring properties they did not have before. One of the main reasons for this aimed genetic modification in plants is herbicide resistance. Especially in soy case is used the modification to resist to glyphosate. The safety of the food which has been made of genetically modified crops or products of animal fed with GM feed has not been proved so far. This bachelor thesis focuses on methods for detection of GMOs in food and feed. Also, it focuses on verifying the data concerning the presence of GMOs presented by companies on food or feed packaging. The research part of this work contains information about genetic engineering, the issue of genetically modified organisms and also focuses on the description of techniques needed to detect GMOs, especially in processed foods, but also in feeds available on the Czech market. The methodical part of this bachelor thesis focuses on the detection of CaMV 35S promoter occurring in DNA crops that have undergone genetic modification. The presence of a specific transgenic material involved the detection of a particular glyphosate-resistant gene, which is particularly known under the trade name Roundup. There were used basic molecular biological methods to analyze GMOs.
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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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