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The effect of tobacco transformation with yeast Spcdc25 gene on root system structure
Čiháková, Klára
Regulation of cell cycle represents a process that is well conserved among eucaryotes. In plants, however, very important part of the system - regulation of G2/M transition remains elusive. Phosphatase, that is responsible for all-or-nothing regulation at mitosis entry in other eucaryotes, has not been found in plants yet. Some authors even suggest that, in plants, the activatory dephosphorylation was replaced by entirely unrelated control mechanism during evolution. One possible way how to study G2/M transition in plants is to characterize impact of expression of foreign (e.g. yeast cdc25) gene coding the phosphatase on plant phenotype. In previous studies of our team, a cytokinin-like effect of expression of cdc25 gene (form S. pombe, Spcdc25) was observed in transgenic tobacco. Segments of Spcdc25 plants were able to form shoots on media without cytokinins, cell shape and cell organisation and carbohydrate status in cell cultures was changed in a way that can be induced by cytokinin application in a control. Plants also exhibited accelerated flowering and reduced root mass. The latter characteristic represents a starting point of this work. The aim of the study was to determine the characteristics of the Spcdc25 plants that can be responsible for root development restriction and select a component of the...
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Characterization of changes induced by Schizosaccharomyces pombe cdc25 gene related to earlier flowering onset
Čiháková, Klára ; Lipavská, Helena (advisor) ; Tylová, Edita (referee)
The study is focused mainly on mechanisms related to flowering acceleration in plants expressing cdc25 from Schizosaccharomyces pombe (Spcdc25 plants). In yeast, the gene in question codes a phosphatase responsible for activatory dephosphorylation at mitosis entry. In higher plants, however, the ortholog has not been identified yet. Some doubts even exist on the importance of this activatory dephosphorylation, though dephosphorylation itself has been documented in plants. Previous studies of our team revealed many differences in Spcdc25 tobacco plants; majority of them can be induced in WT by cytokinin application and thus, the hypothesis of cytokinin-like effect of Spcdc25 expression have been proposed. As the earlier flowering was one of the most pronounced effects, the aim of this study has been to characterize mechanisms, responsible for this phenomenon. The analyses of phloem exudates revealed weak tendency to lower saccharide transport to the apex in transformants. The sacharide content in the apex, however, was similar or slightly higher with significantly higher glucose proportion in transformants. Thus, a role of saccharides in flowering regulation should not be excluded. The analysis of the flowering-inducing genes expression has shown the only change: the expression of the tobacco homologue of...
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Plant competition in the early ontogeny
Čiháková, Klára ; Weiser, Martin (advisor) ; Fendrych, Matyáš (referee)
Competitive impacts on early stages of plant ontogeny are being reviewed in this thesis. Those processes select for evolutionary or phenotypically plastic responses in timing of emergence, seed morphological properties, maternal effects and reaction on environmental cues. However, pattern of the strong selective pressure is sometimes not apparent, due to the lack of data and knowledge on the influence of the other factors in plant's life.
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The effect of tobacco transformation with yeast Spcdc25 gene on root system structure
Čiháková, Klára
Regulation of cell cycle represents a process that is well conserved among eucaryotes. In plants, however, very important part of the system - regulation of G2/M transition remains elusive. Phosphatase, that is responsible for all-or-nothing regulation at mitosis entry in other eucaryotes, has not been found in plants yet. Some authors even suggest that, in plants, the activatory dephosphorylation was replaced by entirely unrelated control mechanism during evolution. One possible way how to study G2/M transition in plants is to characterize impact of expression of foreign (e.g. yeast cdc25) gene coding the phosphatase on plant phenotype. In previous studies of our team, a cytokinin-like effect of expression of cdc25 gene (form S. pombe, Spcdc25) was observed in transgenic tobacco. Segments of Spcdc25 plants were able to form shoots on media without cytokinins, cell shape and cell organisation and carbohydrate status in cell cultures was changed in a way that can be induced by cytokinin application in a control. Plants also exhibited accelerated flowering and reduced root mass. The latter characteristic represents a starting point of this work. The aim of the study was to determine the characteristics of the Spcdc25 plants that can be responsible for root development restriction and select a component of the...
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Sexual education of children with mental disability
ČIHÁKOVÁ, Klára
The thesis deals with the problems of sex education of mentally handicapped children. Elaboration of a model educational programme for pupils of the 7th year of practical primary school is the aim of the thesis. The thesis consists of two parts. The theoretical part of the thesis is divided into three basic chapters. The first chapter deals with definition of the term mental handicap, classification and characteristics of the individual levels of mental handicap, and focuses on characteristics of people suffering from minor mental handicap. The second part focuses on sexuality. It describes sexuality symptoms, sexuality functions and finally sexuality of mentally handicapped people. The third chapter is dedicated to sexual education, namely to its goals, principles, contents and methods. The practical part deals with methodology of elaboration and a proposal of a model educational programme for pupils of the 7th year of practical primary school. This thesis may be used as methodological material for teachers in sex education at practical primary schools.
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