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Growth and development of plant body is dependent on correct and effective integration of information about current deployment of its body parts, as well as on perception and transduction of inputs from environment. Multiple developmental processes within plant body are determined by specific and tightly controlled distribution of molecule with unique signaling mission within plant development - auxin. Spatial distribution of auxin is co-determined by plethora of tightly controlled processes, and the polar auxin transport plays unique role among them. PIN proteins are the plant-specific family of secondary transporters driving movement of auxin across membranes. With their frequent asymmetrical localization within cells, specific expression patterns in developing tissues and their reactiveness to external cues they secure unique, dynamic and asymmetric distribution of auxin within the plant body. This dissertation thesis is focused on characterization of the role different PIN proteins play in determining cellular auxin homeostasis and consequent formation of auxin gradients. Controlled overexpression of PIN proteins in tobacco cells showed, that PIN4 and to some extent also PIN6, function as the direct auxin efflux carriers. In the cellular auxin transport they play the role analogous to other...

Many problems which have an adverse impact on crops, come into the agriculture with global warming the planet and thus changes in regional temperature and humidity regimes. These problems will be significant especially in developing countries that are already interfered by drought and threatened by famine. Therefore major target is developing of plants resistant to these climatic changes. Only the very classical breeding doesn't clearly sufficient for these tasks. However, genetic engineering could contribute significantly by genetically modified (GM) plants. This modern breeding-cultivation technology has several advantages in comparison with traditional breeding. One of them is for example targeted and well-controlled change in genotype, which allows obtaining plants with specific desired properties.

The inhabitants of the Third World have to deal with problems such as population explosion, undernourishment, poverty and morbidity. The Green Revolution saved millions of people from hunger through the introduction of specially bred varieties of cereal in combination with mineral fertilization. The transition from the Green Revolution to the Genetic Revolution, which consists in the introduction of transgenic crops prepared using genetic engineering techniques, could represent the future for developing countries. The work deals with the issue of transgenic crops in developing countries. The first part deals with problems of the Third World, the second part with transgenic crops, specifically the preparation process of these crops, their present and potential use in developing countries and potential risks. The third part includes analysis of the Framework Education Programme for Secondary General Education and analysis of selected textbooks.

The long-term goal of the Laboratory of Biology of Cytoskeleton is to explain in molecular terms the role of microtubules in cellular processes and to characterize proteins associated with microtubules and its organizing centers (MTOCs). The main attention of our research is focused on -tubulin and its role in microtubule nucleation. We have shown previously that besides its localization on centrosomes, -tubulin is found on celullar membranes (Macůrek et al., 2008), plant kinetochores (Dryková et al., 2003) and marginal bend of embryonal chicken erytrocytes (Linhartová et al., 2002). g-Tubulin also interacts with protein tyrosine kinases, that can regulate microtubule nucleation (Sulimenko et al., 2006; Macůrek et al. 2008). There are growing evidence that centrosomal proteins can affect genetic stability of the cell. g-Tubulin is involved in the regulation of the cell cycle (Vardy et al., 2002) and can participate in activation of checkpoint mechanism controlling the integrity of DNA. Recently, it has been proved its interaction with nuclear protein ATR (Zhang et al., 2007) and Rad51 (Lesca et al., 2005). That's why g-tubulin has been connected with the process of cancerogenesis. Cancer cells also display the changes in expression of b-tubulin isotypes (Katsetos et al., 2003). Moreover, increased level of...

There are several members of the subfamily of plant AGC kinases (AGCVIII) suggested to play a role in the regulation of auxin transport, protein kinases PID, WAG1, WAG2 and D6. They all have been shown to perform regulatory phosphorylation of PIN auxin efflux carriers. It is the asymmetrical subcellular localization of PIN proteins that enables the auxin molecules to be transported through a tissue in a polar manner. Regulation of their expression, localization or activity can therefore affect the quantity and directionality of auxin transport. This thesis is focused on better understanding of the PID-mediated regulation of auxin transport. The auxin accumulation as well as the localization of PIN and PID proteins has been studied using stable and transient expression of Arabidopsis thaliana PID in tobacco cell line BY-2. As shown here, the activity of PID does not enhance the activity of PINs, but still it has a positive effect on auxin efflux by increasing the amount of PIN proteins on the plasma membrane. Results presented here suggest that PID-mediated phosphorylation of PIN proteins most likely promotes their exocytosis from endosomal compartments towards the plasma membrane. Using transient co-expression of PID kinase mutated in its ATP-binding site and PIN1-RFP it was shown that functional...

The non-uniform distribution of the plant growth regulator (phytohormone) auxin is known to mediate many fundamental processes in plant development. Auxin is transported through the plant body either via vascular pathways or from cell to cell by specialized polar auxin transport machinery. This machinery consists of a balanced system of passive diffusion combined with the activities of auxin influx and efflux carriers. This work is focused on the processes that are involved in the uptake of auxin into plant cells. On the basis of molecular-biological and biochemical characterization, the function as an auxin influx carrier was confirmed for PaLAX1 protein from wild cherry (Prunus avium). The sequences of isolated cDNA of the PaLAX1 gene and of its protein product are highly similar to both the cDNAs and the corresponding protein products of the AUX1/LAX-type genes, coding for putative auxin influx carriers in model plant A. thaliana. On the level of organs and single cells, we have shown that the overproduction of PaLAX1 in transgenic lines resulted in an increase of the content of native auxin indole-3-acetic acid as well as of the uptake of synthetic auxin, 2,4-dichlorophenoxyacetic acid. Further, the mechanism of action of putative auxin influx inhibitors 1-naphthoxyacetic acid (1-NOA),...

The aim of this thesis is to introduce the concept of organic farming from the point of view of contemporary science in the field of plant biology to secondary school students and their teachers. The first part deals with organic farming, its origins and ideological subtext, further on its advantages and disadvantages are summarized. The second part focuses on biotechnological agriculture which uses breeding methods of genetic engineering. The third part presents possibilities of coexistence and confrontation and comparison of these two approaches used in present and future agriculture. The last part deals with inclusion of this topic into present secondary school education and its significance. It includes analysis of textbooks and curricular documents.

in English Plants with their sessile life-style are exposed to many stimuli from environment. They have developed mechanisms how to coordinate their growth and development, which allows them to survive sometimes in very difficult conditions. Plant hormones are one of the most important regulators of this signal transduction. Auxins, as the oldest known group of plant hormones, play important role in many physiological processes in plants. To allow perceiving the information in every single cell, auxin molecule is transported by cell-to-cell manner. Auxin molecules enter the cell by passive diffusion or by active uptake by auxin influx carriers. To reach the next cell, they are transported actively out of the cell by auxin efflux carriers. Athough active auxin transport has been studied for almost four decades, past two decades contributed to the identification and characterization of particular auxin carriers remarkably. This thesis contributes to the knowledge on the auxin efflux and influx carriers and their involvement in the processes occurring from a single cell level to the level of a whole plant. Firstly, it brings detailed description of auxin transport characteristics in Arabidopsis thaliana cell suspension cells (Ath cells). Secondly, it shows that the overproduction of PIN1 auxin efflux...

In multicellular organisms, programmed cell death (PCD) is an essential mechanism during development, morphogenesis and during the interaction with the environment. The regulation of PCD is highly regulated and conserved throughout the evolution. Animal apoptosis is the best described PCD type which is characterized by the condensation of cytoplasm, specific DNA fragmentation and the formation of apoptotic bodies which are finally engulfed by neighboring cells. Due to the structural specificities of plant cells, plant PCD exhibits rather autophagic character. In mammals, DSBs-induced PCD is mainly governed by ATM kinase. This response also involves downstream ATM effectors like p53 and E2F factors. P53 stabilization leads to the cell cycle arrest in G1/S whereas E2F can promote apoptosis by activating PCD-related genes including caspases. PCD could be induced also by E2F ectopic expression. In spite of a conservation of PCD signaling among Eukaryotes, number of animal PCD regulators was not identified in plants (caspases, p53), thus in plants the PCD response induced by DSBs is still poorly understood. On the contrary, E2F transcriptional factor is conserved between animals and plants but its role during plant PCD was not evaluated till now. The main goal of my thesis was to characterize the PCD in...

Genetically modified crops (GM crop) are plants which have changed their genotype by molecular-genetic techniques. Targeting interventions into plant genotype have higher efficiency in comparison to methods, which are used in classical breeding. Essential presumption of these interventions is profound knowledge of molecular biology, genetics and plant physiology. The success of genetic modifications is dependant upon increasing knowledge from many branches of biology. The first generation of GM crops was resistant to abiotic stress, pests, herbicides or diseases. The outcome of this is increase of yields and overall decrease of costs. These qualities bear profit especially for farmers but not for end-users. Many methods, which are used for transformation of the first generation of genetically modified crops, are used for next generations as well. Biofortification could be considered as the next step of genetic modification of crops. Plants, which are consuming, are improved by substances, which prosperous to the human body. They should partly substitute the variety of food and to help improve the nutrition, but they don't have curative effects. Molecular-genetic principles of their creation are very similar to molecular farming. Nowadays the molecular farming presents the top of genetic...

4.CONCLUSIONS 1. Cadmium ions and cold strrcssrcliably induced cell death, in particular programmed type 2. Programmed cell death was accompanied only by several, but limitedn specific morphological changes 3. The occurnenceof internucleosomď DNA fragmentationis is not a rcliab|e indicator of PCD 4. Particular cell cycle phasesyield to 50pM CdSO4 trcatment with a different intensity 5. Different strcssconditions induced nuclear ma|formďons, which werrchowever,probably not interrclated to PCD 21

1. ABSTRACT An actin cytoskeleton comprises an essential cytoskeletal structure that organizes a cytoplasm during number of processes occurring in animal and plant cells, such as cell division and growth, formation of membrane protrusions and cellular movement or cytoplasmic streaming. A dynamic actin net and an exact spatial and temporal actin filament organization is, therefore, necessary for correct growth processes and development of multicellular organism. Depolymerization and re-establishment of actin arrays is mediated by actin associated proteins. Among them, an Arp2/3 complex (actin related protein 2 and 3) plays an important role as a catalyst of the actin filament nucleation and, thus, enables the formation of dynamic actin network. In non-plant cells, Arp2/3 complex-dependent polymerization of actin filaments is required for movement of whole cells (fibroblasts or keratocytes), it drives organels and pathogens throughout the cell or mediates endocytic processes. The role of the Arp2/3 complex in non-motile plant cells is despite the considerable effort over last three years far from being understood. Unlike animals, where loss-of-function mutations in the Arp2/3 complex are lethal, only limited number of cell types show significant phenotype in Arabidopsis mutants. The evidence exists that the...