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Cell inclusions in microscopic eukaryotes
Pilátová, Jana
This thesis reports, for the first time, a systematic study identifying various cell inclusions across the broad diversity of all major eukaryotic supergroups. Raman microspectroscopy technique was employed as a powerful technique, which is becoming the method of the first choice for such studies. In Chapter 1, the spatial reconstruction of chloroplasts of the unicellular zygnematophyte Cylindrocystis sp. (Streptophyta) revealed "empty spaces" inside. Subsequent analysis showed massive accumulations of polyphosphate, which is not located in the cytoplasm as in other species, but inside the chloroplasts. This newly discovered ability of the zygnematophytes, a sister group of terrestrial plants, to accumulate polyphosphate leads us to speculate about a possible adaptation to extreme Arctic conditions or even a preadaptation leading to plant terrestrialization. Chapter 2 summarizes the serendipitous discovery of purine crystalline inclusions in dinoflagellates and other microalgae. Investigated dinoflagellate species comprised zooxanthellae, the endosymbionts of reef-building corals, and the species causing toxic algal blooms. Purine crystals were further shown to act as dynamic high-capacity nitrogen storage. To show how widespread purine inclusions are, a revision of crystalline inclusions in all...
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Cell inclusions in microscopic eukaryotes
Pilátová, Jana ; Schwarzerová, Kateřina (advisor) ; Gierlinger, Notburga (referee) ; Prášil, Ondřej (referee)
This thesis reports, for the first time, a systematic study identifying various cell inclusions across the broad diversity of all major eukaryotic supergroups. Raman microspectroscopy technique was employed as a powerful technique, which is becoming the method of the first choice for such studies. In Chapter 1, the spatial reconstruction of chloroplasts of the unicellular zygnematophyte Cylindrocystis sp. (Streptophyta) revealed "empty spaces" inside. Subsequent analysis showed massive accumulations of polyphosphate, which is not located in the cytoplasm as in other species, but inside the chloroplasts. This newly discovered ability of the zygnematophytes, a sister group of terrestrial plants, to accumulate polyphosphate leads us to speculate about a possible adaptation to extreme Arctic conditions or even a preadaptation leading to plant terrestrialization. Chapter 2 summarizes the serendipitous discovery of purine crystalline inclusions in dinoflagellates and other microalgae. Investigated dinoflagellate species comprised zooxanthellae, the endosymbionts of reef-building corals, and the species causing toxic algal blooms. Purine crystals were further shown to act as dynamic high-capacity nitrogen storage. To show how widespread purine inclusions are, a revision of crystalline inclusions in all...
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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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