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Role of exocyst complex in growth and development of moss Physcomitrella patens
Rawat, Anamika Ashok ; Žárský, Viktor (advisor) ; Binarová, Pavla (referee) ; Fendrych, Matyáš (referee)
During the course of evolution the early land plants gained extensive innovations that can be seen in modern day plants. The polar growth is an ancient feature of eukaryotic cells and is one of preadaptations that helped plants in successful colonization of land. The polar growth in plants regulates not only the direction of cell expansion and structural properties of cell wall but especially also the orientation of cell division, and is governed by various factors, including the exocyst complex. The exocyst is a well conserved vesicle tethering multi-subunit complex involved in tethering of secretory vesicles to the target membrane. The essential role of the exocyst complex in regulation of various cellular processes in Angiosperms is now well documented. Here I present results of a doctoral project that contributed to phylogenetic analyses of the land plant exocyst complex and especially to uncovering functions of three moss exocyst subunits, namely EXO70 (isoform PpEXO70.3d), SEC6 and SEC3 (isoforms PpSEC3A and PpSEC3B) in the model organism Physcomitrella patens. Various knock-out (KO) mutants in several moss exocyst subunits (Ppexo70.3d, Ppsec6, Ppsec3a and Ppsec3b) show pleiotropic defects directly or indirectly linked to the cell polarity regulation. Cell elongation and differentiation,...
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Kortikální cytoskelet, exocytický komplex exocyst a jejich role v morfogenzi rostlinných buněk
Fendrych, Matyáš ; Žárský, Viktor (advisor) ; Baluška, František (referee) ; Hašek, Jiří (referee)
Plant cell morphogenesis is largely dependent on the coordination of cytoskeletal elements, plasma membrane, and vesicle trafficking. Formin proteins are nucleators of the actin cytoskeleton. Plant Class I family formins are integral membrane proteins and thus have the ability to coordinate cytoskeletal dynamics with the plasma membrane localization. We identified Arabidopsis thaliana formin AtFH4 as a microtubule associated protein. The binding is conferred by a novel domain located between the transmembrane domain and the formin homology 1 domain. The protein associated with actin in in vitro conditions. Overexpressed AtFH4 accumulated in the endoplasmic reticulum, and induced coalignment of endoplasmic reticulum membranes with microtubules. Together, these data suggest that the combination of plant-specific and conserved domains enables AtFH4 to function as an interface between membranes and both major cytoskeletal networks . Secretory pathways supported by the activity of the Golgi apparatus play a crucial role in cytokinesis in plant cells. Prior to their fusion with the plasma membrane, secretory vesicles are tethered at exocytic sites by the exocyst, an octameric protein complex. We analysed the mutant in the EXO84b exocyst subunit, and discovered that the mutant plants were dwarfed and exhibited...
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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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Advanced methods of endocytosis and exocytosis visualisation on plant cell membrane
Ortmannová, Jitka ; Fendrych, Matyáš (advisor) ; Krtková, Jana (referee)
Endocytosis and exocytosis participate in developmental program of plants.The ability to target exocytic vesicles to particular domains of plasma membrane is crucial for polarization, growth and development. Plasma membrane are recycled via various mechanisms of endocytosis which participates also in establishing plant cell polarity. To extend our knowledge of membrane transport it is essential to observe the activity of its components with high resolution in living cells of intact organisms in real time. Such methods belong mainly into the field of light microscopy and nanoscopy exceeding often diffraction limit (200 nm). Nanoscopic techniques like PALM, STORM, SIM, STED, offer multicoloured visualization of fluorophores and high resolution 3D reconstruction of cellular component. These methods have been used only sporadically in the field of plant biology but there should be no serious obstacles for they employment. The key words: clathrin, difraction limit, endocytosis, exocytosis, exocyst, fluorophore, plant cell, microscopy, resolution
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