National Repository of Grey Literature 3 records found  Search took 0.00 seconds. 
Jiráková, Klára ; Moskvin, Maksym ; Horák, Daniel ; Jendelová, Pavla
Cells labelled with iron oxide nanoparticles (ION) can be tracked by magnetic resonance imaging (MRI) in several applications. However, various studies demonstrated toxicity and oxidative stress induction associated with nanoparticles exposure. We analysed biologic effects after the exposure of two types of iron oxide nanoparticles (with and without an antioxidative agent; an ascorbic acid) on human neural stem cells. The labelled cells in gel phantoms were detected in MRI and they showed decreased relaxation rates in comparison with control. ION slightly decreased cell proliferation in comparison with unlabelled cells, which was dependent on concentration and presence of ascorbic acid. None of the nanoparticle type showed negative effect on cell viability and both demonstrated minor effect on reactive oxygen species (ROS) formation. Unfortunately, ascorbic acid bound to nanoparticles did not show any effect on ROS attenuation. Cells exposed to both types of nanoparticles showed increased positivity for a phosphorylated form of H2AX a marker of double strand breaks. We showed that ION in low concentrations do not affect cell viability, but have negative effect on cells on DNA level. Their potential use for oxidative stress reduction is dependent on the concentration of ascorbic acid bound to the nanoparticles and this should be further increased.
Cell cycle and differentiation in Giardia Intestinalis
Jiráková, Klára ; Nohýnková, Eva (advisor) ; Doležal, Pavel (referee) ; Müller, Norbert (referee)
Giardia is a unicellular parasitic organism; it is a worldwide cause of human diarrhea. It has minimalistic genome equipment and simplified molecular and metabolic pathways. In this respect, it is a suitable model organism for studying cell cycle regulation and to define the minimal genetic and protein equipment required for the functional reproduction of the eukaryotic cell. Its life cycle comprises of two stages; a pathogenic trophozoite and an infective cyst, which can survive in outer environment. New knowledge about encystation can be therapeutically important because this process is a target for vaccine and drug development. Since cell cycle analysis requires a synchronized population, we studied the effect of the synchronization drug aphidicolin on individual cell characteristics during the cell cycle of Giardia trophozoites. Our results showed that aphidicolin caused inhibition of DNA synthesis and trophozoites were aligned according to their DNA content in G1/S border. Subsequent inhibition of entry into mitosis and cytokinesis indicates, that Giardia has functioning DNA damage checkpoint. Extensive treatment with aphidicolin causes side effects. We detected positive signals for phosphorylated histone H2A which, in mammalian cells, is involved in a signaling pathway triggered as a reaction...
Nuclei of Giardia intestinalis
Krížová, Kateřina ; Nohýnková, Eva (advisor) ; Jiráková, Klára (referee)
4 Abstract Giardia intestinalis is a protozoan parasitic organism early diverging from common ancestor of all eukaryotes. That is why many distinctions of structure and ongoing processes occure in Giardia. Although the current findings suggest that a number of features and simplicity may be given to adaptation of the parasitic way of life, Giardia still remains a unique model, which may indicate something about many of the "core" processes that define eukaryotic cells. This paper summarizes a lot of known information related to two morphologically similar nuclei of Giardia. The nuclei have been compared both with each other and with the general knowledge of the eukaryotic nucleus. Although initially the nuclei were considered to be exactly the same, more recent studies and researches have brought plenty of evidence that they differ from each other. The main difference is basically the unequal content of chromosomes in each nucleus. Other differences consist in the number and deployment of nuclear pores or in the synchronization of the cell cycle. Special type of mitosis occurs there as well. Even though many claims have been clarified and refuted since the first study confirming the identity of nuclei was published in 1990, a lot of information needed for a complete understanding of the functioning of the...

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3 JIRÁKOVÁ, Kristýna
3 Jiráková, Kristýna
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