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Mechanical forces in asymmetric cell division
Šabata, Vojtěch ; Macůrková, Marie (advisor) ; Middelkoop, Teije Corneel (referee)
Cell division is one of the most studied topics in the field of cellular and molecular biology. In some cases, cells can exploit diverse mechanisms to alter the basic function of their division machineries to divide asymmetrically. This results in two daughter cells that differ from each other in some manner, which is an essential premise for the development and adult homeostasis of complex multicellular organisms. This work is focused on the division of Caenorhabditis elegans zygote, a classic example of asymmetric division. Using this model system, this work highlights the cellular mechanisms used to generate polarity, with emphasis on the purely mechanical aspects present. In recent years, great progress has been made in describing these fundamental pathways, which are at their core highly conserved from nematodes to humans. Deeper knowledge of processes, that are responsible for a successful cell division in general, can be beneficial for a better understanding of organismal development in health and disease.
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Cell polarity establishment and changes during Saccharomyces cerevisiae cell cycle
Luxová, Pavla ; Malcová, Ivana (advisor) ; Šťovíček, Vratislav (referee)
Cell polarity can be defined as an asymmetric organization and distribution of biomolecules, cellular organelles and structures which are important for many cellular processes. Cell polarity establishment is essential for the proper development of all organisms. This work focuses on main mechanisms of cell polarity establishment, its maintenance and changes during Saccharomyces cerevisiae cell cycle. Budding yeast is one of the preferred model organism. Bud site selection is determined by the spatial landmarks which are accumulated at the previous division site. The spatial landmarks are recognized by Rho GTPases which act on their effectors and thus affect the actin cytoskeleton and septins. These structures are essential for polarized bud growth that is coordinated with the cell cycle. Newborn cells arising after the bud separation from the mother cell at the end of each cycle are able to undergo many more division cycles than their mothers what is a new challenge to study cell polarity in terms of cell aging.
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Regulation of cell cycle in Bacillus subtilis.
Zelenka, Tomáš ; Lichá, Irena (advisor) ; Harant, Karel (referee)
2 Abstract Relations between several events running in bacterial cell during cell cycle were the subject of many studies during last years. More advanced techniques showed, that bacterial cell life has much more variable factors, than we supposed before. Relatively recent researches managed to reveal function and in few events molecular principle of several mechanisms coordinating those events such as progression of replication and its initiation, segregation of newly replicated chromosomes and after all synchronization of complex cell division machinery. Furthermore it showed variability of those events during changing living conditions of the cell. Keywords: Cell cycle, regulation, initiation, replication, segregation of chromosome, cytokinesis, Bacillus subtilis
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Mechanisms of establishment and maintenance of PIN polarity in Arabidopsis
Glanc, Matouš ; Friml, Jiří (advisor) ; Grebe, Markus (referee) ; Luschnig, Christian (referee)
Cell polarity is a key concept in plant biology. The subcellular localization of Pin- formed (PIN) auxin efflux carriers in the root of "#$%&'()*&* is remarkably asymmetrical, making PINs prominent markers to study cell polarity. In spite of its developmental importance and two decades of research, the molecular basis of PIN polarity remains largely unknown. In this thesis, I employed advanced transgenic and fluorescence microscopy approaches to gain insight into several aspects of PIN polarity regulation. I participated in establishing a novel genetically encoded inhibitor of endocytosis, an invaluable tool for the study of the importance of endocytosis for various cellular processes, including PIN polarity. I demonstrated that apical polarity of PIN2 needs to be re-established after cell division and that this process depends on endocytosis, '+!,(-( protein secretion and the action of WAG1 and related protein kinases, but not transcytosis, cell-cell signaling or intact cytoskeleton. Finally, I identified the previously unknown role of MAB4/MEL proteins in PIN polarity, which lies in the ability of MAB4/MELs to reduce PIN lateral diffusion and thus contribute to PIN polarity maintenance. My results, besides broadening current understanding of PIN polarity regulation, identify mechanisms that...
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Mechanisms of establishment and maintenance of PIN polarity in Arabidopsis
Glanc, Matouš ; Friml, Jiří (advisor) ; Grebe, Markus (referee) ; Luschnig, Christian (referee)
Cell polarity is a key concept in plant biology. The subcellular localization of Pin- formed (PIN) auxin efflux carriers in the root of "#$%&'()*&* is remarkably asymmetrical, making PINs prominent markers to study cell polarity. In spite of its developmental importance and two decades of research, the molecular basis of PIN polarity remains largely unknown. In this thesis, I employed advanced transgenic and fluorescence microscopy approaches to gain insight into several aspects of PIN polarity regulation. I participated in establishing a novel genetically encoded inhibitor of endocytosis, an invaluable tool for the study of the importance of endocytosis for various cellular processes, including PIN polarity. I demonstrated that apical polarity of PIN2 needs to be re-established after cell division and that this process depends on endocytosis, '+!,(-( protein secretion and the action of WAG1 and related protein kinases, but not transcytosis, cell-cell signaling or intact cytoskeleton. Finally, I identified the previously unknown role of MAB4/MEL proteins in PIN polarity, which lies in the ability of MAB4/MELs to reduce PIN lateral diffusion and thus contribute to PIN polarity maintenance. My results, besides broadening current understanding of PIN polarity regulation, identify mechanisms that...
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Endocytic transport in cytokinesis
Koudelová, Kristina ; Libusová, Lenka (advisor) ; Vosolsobě, Stanislav (referee)
Cytokinesis represents a very complex and highly orchestrated process. For many years, the mechanism of animal cell cytokinesis was described as a result of actomyosin ring constriction. By contrast, in plant cells the division was seen as an outcome of vesicle fusion at the cell plate region between two daughter cells. Recent studies, however, uncover the involvement of vesicular trafficking in animal cell cytokinesis. This thesis aims to highlight the importance of endocytic transport and the necessity of its proper regulation. At first, the origin of vesicles is debated. Afterwards, three main types of endocytic vesicles are examined - Rab11/FIP3 endosomes, Rab35-endosomes and PI(3)P-enriched endosomes, along with their function and interacting partners. Finally, the attention is given to the mechanism of abscission and midbody inheritance. Ongoing processes are accompanied by changes in membrane composition, cytoskeleton reorganization and targeted delivery of distinct cargo molecules. Failure in cytokinesis has been implicated in the etiology of many diseases, such as cancer. Therefore, better understanding of associated endocytic trafficking may provide us with new therapeutic strategies.
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Cell polarity establishment and changes during Saccharomyces cerevisiae cell cycle
Luxová, Pavla ; Malcová, Ivana (advisor) ; Šťovíček, Vratislav (referee)
Cell polarity can be defined as an asymmetric organization and distribution of biomolecules, cellular organelles and structures which are important for many cellular processes. Cell polarity establishment is essential for the proper development of all organisms. This work focuses on main mechanisms of cell polarity establishment, its maintenance and changes during Saccharomyces cerevisiae cell cycle. Budding yeast is one of the preferred model organism. Bud site selection is determined by the spatial landmarks which are accumulated at the previous division site. The spatial landmarks are recognized by Rho GTPases which act on their effectors and thus affect the actin cytoskeleton and septins. These structures are essential for polarized bud growth that is coordinated with the cell cycle. Newborn cells arising after the bud separation from the mother cell at the end of each cycle are able to undergo many more division cycles than their mothers what is a new challenge to study cell polarity in terms of cell aging.
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Regulation of cell cycle in Bacillus subtilis.
Zelenka, Tomáš ; Lichá, Irena (advisor) ; Harant, Karel (referee)
2 Abstract Relations between several events running in bacterial cell during cell cycle were the subject of many studies during last years. More advanced techniques showed, that bacterial cell life has much more variable factors, than we supposed before. Relatively recent researches managed to reveal function and in few events molecular principle of several mechanisms coordinating those events such as progression of replication and its initiation, segregation of newly replicated chromosomes and after all synchronization of complex cell division machinery. Furthermore it showed variability of those events during changing living conditions of the cell. Keywords: Cell cycle, regulation, initiation, replication, segregation of chromosome, cytokinesis, Bacillus subtilis
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