|
|
The Role of Lipids and Lipid Metabolizing Enzymes in Plant Autophagy
Krupař, Pavel ; Martinec, Jan (advisor) ; Hála, Michal (referee)
Plant autophagy is a crucial evolutionary conserved process for recycling cytoplasmic material under stress conditions or during development. The autophagic pathway is negatively regulated by TOR kinase, a versatile molecule modulating a wide range of cellular processes. In mammals, TOR kinase may be activated by phosphatidic acid, a vital signalling lipid. This thesis aims to prove the possible involvement of phospholipids in plant autophagy. I analysed the rate of primary root inhibition in knock-out mutants coding phospholipases in A. thaliana with induced autophagy, measured activity of lipid metabolising enzymes in wild type and atg10 mutant and observed autophagosome formation in selected mutants. Autophagosomes were labelled by fluorescent protein in vivo and by indirect immunolabelling in fixed samples. Using advanced stereological approach, I optimized a method for obtaining an unbiased estimate of autophagosome number in plant root cells.
|
|
|
Actin and the ARP 2/3 complex in the nucleus
Němcová, Barbora ; Bellinvia, Erica (advisor) ; Hála, Michal (referee)
The eukaryotic actin cytoskeleton is required for numerous cellular processes, including cell shape, development and movement, gene expression and signal transduction, and response to biotic and abiotic stress. Actin constitutes a wide family of proteins that are major components of the cytoskeleton. Actin is one of the most abundant proteins in living organisms. Actin has essential functions both in the cytoplasm and in the nucleus, where it has been linked to key nuclear processes. Recent studies have shown that actin is actively transported from the cytoplasm to the nucleus, where it regulates transcriptional aktivity, regulates RNA polymerases, is involved in chromatin remodeling and repair damaged DNA. The presence of typical actin filaments in the nucleus has not been demonstrated directly.but nuclear actin occurs in many forms such as actin rods, short actin polymers, actin monomers, or actin complexes with profilin or cofilin. Most eukaryotic cells also contain at least eleven actin-related proteins (ARPs). Although many ARPs are cytoskeletal, recent biochemical and genetic work has demonstrated that some ARPs function largely or entirely in the nucleus. Nuclear ARPs are recognized as novel key regulators of genome function, and affect not only the remodeling of chromatin but also the...
|
|
|
Function of the AtKUP5 transporter in Arabidopsis thaliana
Štočková, Hana ; Tylová, Edita (advisor) ; Hála, Michal (referee)
Potassium is one of the essential elements necessary for plant growth. It is involved in many plant processes, such as osmoregulation, enzymes activaton, etc. These functions are very often closely related to its transport in the cell and the whole plant. Although potassium is abundant in earth's crust, the mount of plant-available form is often insufficient. Potassium deficiency manifests itself on many levels and also contributes to the reduction of yield and quality of agricultural crops. There are many of potassium-transporting proteins in the plant. One of the important families of potassium transporters is the KT/HAK/KUP family. This family includes, among others, the high-affinity transporter HAK5, which is key for the uptake of potassium from the environment with low-potassium availability. One of the not very characterized transporters from the KT/HAK/KUP family is the KUP5 transporter, which I deal with in my diploma thesis. The aim of this work is to analyze the phenotypic manifestations of kup5 T-DNA insertion mutants and to characterize the functions of the transporter KUP5 in Arabidopsis thaliana plants. I analyzed the growth of kup5 insertion mutants in various environmental conditions and performed plant transformation to determine the localization of the KUP5 transporter in the...
|
|
|
Stomata opening and closure regulation in respect to osmotic stress
Hofírková, Miroslava ; Hála, Michal (advisor) ; Lhotáková, Zuzana (referee)
Stomata are structures located in higher plants' epidermis and they regulate mainly CO2 intake and transpiration. The stomata are important for plants' protection against excessive water loss during osmotic stress. This thesis is a literary research summarizing stomatal movements regulation during osmotic stress. The main part of the thesis is focused on stomatal closure with the help of ABA under water deficiency conditions. There are the ABA synthesis, transport and its impact on stomata described in individual chapters. The ABA early signalling pathway and an ionic channel regulation are described in detail on the basis of the published data. The second part of the thesis is about second messengers produced by ABA and their impact on stomatal movement regulation. The special attention is paid to hydrogen peroxide and nitric oxide and their contribution to stomatal closure. The last part is about passive (hydraulic) stomatal closure. Keywords: plants, stomata, osmotic stress, ABA, stomatal movements
|
|
|
Cuticle, its formation and importance in resistance of plants to abiotic stress
Litkeiová, Veronika ; Hála, Michal (advisor) ; Tylová, Edita (referee)
Plants are daily exposed to stress, biotic or abiotic. Both of these types can be divided into several subgroups. This work is focused on plant cuticle, its formation and function in respect to abiotic stress resistance. The main factors, mentioned in this work, are drought, heat, UV radiation, excessive salinity or ozone exposure. The individual chapters focus on the composition, biosynthesis and changes in the build-up construction caused by certain types of stressors. A significant part is also devoted to cutin and cuticular waxes, which play an important role in plant protection and whose structure is also affected by abiotic stress. Phytohormones, especially abscisis acid, which had its application here, are also not omitted. In the final phase of the thesis, cuticular mutants are mentioned in connection with abiotic stress types illustrating the role and the importance of the cuticle layer. Key words: plants, cuticle, osmotic stress, abscisic acid, cutin, waxes
|
|
|
Plant tomosyns and their role in secretion
Dejová, Lilly ; Hála, Michal (advisor) ; Fendrych, Matyáš (referee)
Tomosyn is a protein belonging to the Lgl family and conserved across the animal and plant kingdom. Tomosyn is composed of N-terminal domain containing WD40 motif and Cterminal domain, where the R-SNARE motif is located at the end of the C-terminal domain. This motif is classified as homologous to R-SNARE motif of synaptobrevine, which is a protein located on the surface of the vesicles and participating in the formation of SNARE complex and subsequent fusion of the vesicles with the plasma membrane. Thus the role of this tomosyn is mainly the regulation of exocytosis. Apart from the animal tomosyn, its yeast homolog Sro7/Sro77 is also examined, however during the evolution it has lost its R-SNARE motif and therefore the plant tomosyns remain unexplored. The aim of this diploma thesis was to characterize both of the plant tomosyns: AtTYN1 and AtTYN2 in Arabidopsis thaliana plant. The experimental thesis included the bioinformatic analysis, the DNA construct creation, a search for interactors by yeast two-hybrid system and monitoring the localization using the confocal microscope. The bioinformatic analysis results, including the creation of phylogenetic tree, not only revealed the conservation of tomosyns across the different classes, but also the division of both tomosyns into different clusters. There was...
|
|
|
Coat protein-RNA interaction in vivo and the biotechnological use of VLPs
Kratochvílová, Kateřina ; Moravec, Tomáš (advisor) ; Hála, Michal (referee)
The Tobacco mosaic virus (TMV) is a simple and frequently used model virus which has been studied already more over than 130 years. Due to the intensive study of this virus the details of its infectious cycle, genomic information and also the structure of the created viral particle as well as the mechanism of its creation are known today. The process of encapsidation (viral particle formation) is sufficiently described in the in vitro conditions. In the in vitro conditions the origin of assembly (OAS) was also described. The OAS was identified in the coding sequence of the gene for the movement protein (MP). The importance of replication centers (replication factories) has also been supposed. The aim of the diploma thesis was to study the specificity of the interaction of RNA and coat protein in the process of the particle assembly taking place directly inside the plants. The experiments were performed to verify the necessity of presence of OAS sequence in process of initiation of viral encapsidation. The effect of the cell compartmentation on this process has also been studied. Based on several viral systems (the Tobacco mosaic virus, the Potato virus X, the Bean yellow dwarf virus and Cowpea mosaic virus) gene constructs were created. These constructs enables to study this idea at the molecular...
|
|
|
Endocytosis in plants
Svitáková, Lenka ; Krtková, Jana (advisor) ; Hála, Michal (referee)
Endocytosis is a process typical for eukaryotic cells. It is a mechanism that ensures invagination of the plasma membrane which leads to the creation of a membrane vesicle with specifically selected cargo. The vesicle is then internalized by the cell. Endocytosis has a crucial role in plant growth and development not only thanks to the reception of nutrients from the extracellular space but also by having a huge impact on the membrane composition which influences cellular signalling. There are few types of endocytosis known in plants. They differ from each other by the molecular machinery which ensures their process. The most studied type in plants is the clathrin-mediated endocytosis. Clathrin-coated vesicle formation proceeds through five stages. However, there are less details known about it in plant cells than in animal cells. In the first part of my bachelor thesis I describe recent knowledge of this topic and the most important participants in this process. I also mention the mechanisms of regulations that plant cells use to coordinate clathrin-mediated endocytosis. In the second part I summarize recently discovered types of endocytosis in plants that are independent from clathrin. These are endocytosis associated with microdomains and fluid- phase endocytosis. The details of these endocytic...
|
|
| |
|
|
Functions of RAB GTPases and SNARE proteins in post-Golgi trafficking pathways in response to abiotic stress in plants
Moulík, Michal ; Hála, Michal (advisor) ; Mašková, Petra (referee)
Plants as sessile organisms are strongly affected by abiotic and biotic stress factors. Thus, they have developed an array of morfological, biochemical and physiological adaptations to reduce the negative effects of these factors. The membrane trafficking, among others, plays very important role in adaptation to abiotic stress. In my bachelor thesis I have focused on two important protein families involved in this trafficking, namely on RAB GTPases and SNARE proteins. In the first part, the phenomenon of stress is characterized and the strategies how plants cope with the effect of stressors are described, especially the production of reactive oxygen species (ROS) and autophagy. Following chapter deals with an introduction to the membrane trafficking in plants. In the rest of the thesis, I characterize RAB GTPases and SNARE proteins and provide contemporary insight in the mechanism of their function. The aim of the key parts of these chapters is to summarize current knowledge of RAB GTPases' and SNARE proteins' functions in post-Golgi trafficking pathways during response to abiotic stressors or secondary oxidative stress. Key words: plants, abiotic stress, membrane trafficking, secretion, endocytosis, vacuole, RAB GTPases, SNARE proteins
|
guest ::
RSS feed.