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Replication and transcription of nucleolar DNA
Flusser, Michal ; Smirnov, Evgeny (advisor) ; Staněk, David (referee)
The nucleolus is the most prominent compartment of the cell nucleus and is the place where ribosomal RNAs (rRNAs) are synthesized, processed and assembled with ribosomal proteins. Although the nucleolus has been studied for decades its structural and functional organization is still unclear. In particular, the role of various types of DNA participating in the formation of nucleoli along with ribosomal genes is not understood. The present thesis summarizes the current knowledge and views on the nucleolus, focusing on the two synthetic processes, replication and transcription, in mammalian cells. Specific features of these processes in the context of nucleolar ultrastructure remains an unsolved problem of the modern molecular biology.
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Role of PML in nucleolar functions
Kučerová, Alena ; Hodný, Zdeněk (advisor) ; Skalníková, Magdalena (referee)
Promyelocytic leukemia protein (PML) is a tumour suppressor which is frequently downregulated in human tumours. PML plays a role in many cellular processes including DNA damage response, senescence and apoptosis and is mainly localized in special structures called PML nuclear bodies (PML NBs). The nucleolus is a key nuclear compartment, where transcription of ribosomal DNA and biogenesis of ribosomes take place. The nucleolus is also called a stress sensor because of its role, for instance, in stabilization of tumour suppressor p53. Localization of PML to the nucleolar periphery appears to be prominent after disturbance of nucleolar functions - for example inhibition of rRNA transcription or processing. Thus the relationship between the nucleolus and PML nuclear bodies may be important for cellular response to stress. However, the role of PML nucleolar associations in nucleolar function including mechanism of formation of these structures remain unclear. Here we characterised PML nucleolar structures and mechanism of their formation. We showed that formation of PML nucleolar structures is not caused by replication stress, is not dependent on any specific phase of cell cycle and is not caused by DNA damage response but is induced by topological stress due to inhibition of toposiomerase function....
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Cytochemická vyšetření akvitivity nukleolů po podání genisteinu na modelovém objektu
PICMONOVÁ, Veronika
This thesis deals with exploration of the effect of genistein on proteosynthetic activity of nucleoli by observing changes in their morphology. The effect of genistein on the function of nucleoli was observed in hemocytes of the experimental animal Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). 4 types of hemocytes were found in the hemolymph of S. littoralis (Boisduval): granulocytes, prohemocytes, plasmatocytes and spherulocytes. The effect of genistein on individual types and concentration of hemocytes is not clear. Genistein was applied in doses of 0,135 mg and 0,54 mg per larva, and subsequently changes in morphology, number and size of nucleoli were examined upon 8 and 24 hours. Furthermore, changes in morphology of the hemocytes were examined, as well as their concentration using toluidine blue staining, silver staining, panoptic staining and using the Türk{\crq}s solution. For the purpose of changes assessment, the material was processed using an optical microscope and the computer software Nis Element AR 2.30. In the course of observation, changes in the number of nucleoli were found upon application of genistein. The number of compact nucleoli and micronucleoli increased. On the contrary, the number of ring-shaped nucleoli decreased. The area of nucleoli increased upon application of lower dosage of genistein (0,135 mg); however, upon action of the higher dose (0,54 mg), it decreased, on the contrary. Nucleolar index values remained without rather significant changes. In the biomodel used, genistein evoked changes which can be viewed as immune responses from the viewpoint of hematotoxicology.
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