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Self-regulating mechanisms of photosynthetic systems
Semerák, Matěj ; Mančal, Tomáš (advisor) ; Holá, Dana (referee)
Photosynthesis, a process utilising energy of arriving photons for driving electron transport chain creating transmembrane pH gradient, is a widespread way of subsistence in the nature. However, the intensity of sunlight can exceed the rate which the organisms are able to manage by their gadgetry. In this situation, essential protective mechanisms, safely draining the excess energy away, take a turn. Many theories about the principle and regulation of these functions have been developed and new still arise. It appears that the attention focuses mainly on the antenna complex LHCII. It is possible to state that with high probability, the protective processes are assured by several mechanisms, and quite a stable opinion prevails that crucial role in their activation is played by decreasing pH. That is logical since the more photons come, the more intensively the transport of protons across the membrane happens, thus ΔpH reflects the balance between ATP usage and the membrane apparatus illumination. Generally, the phenomenon is called NPQ (non-photochemical quenching), because it weakens the chlorophyll fluorescence. An important task is probably handled by carotenoids, mainly zeaxanthin, created by violaxanthin deepoxidase at low pH; it provides chlorophylls with energetical trap during excitation...
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Photosystem I: from bacteria to green plants
Palovská, Markéta ; Holá, Dana (advisor) ; Matyska Lišková, Petra (referee)
Type I Photosystems (PS) are characterized by a Fe-S cluster that serves as the terminal electron acceptor. They are present in 4 prokaryotic groups and all photosynthetic eukaryotes. This work summarizes the knowledge on the structure and function of PS I subunits. The simplest PS (homodimeric; only 2 subunits) is present in Heliobacteria. PS of green sulphur bacteria is also homodimeric and consists of 4 proteins including a membrane-bound cytochrome. The homodimeric PS of Candidatus Chloracidobacterium thermophilum is functional in aerobic conditions. The reaction center of the well-characterized PS I of Cyanobacteria has a heterodimeric structure; the same applies for the eukaryotic PS I. Cyanobacterial PS consists of 12 proteins and forms trimers under low light conditions. The trimer formation is completely suppressed in green plants. Their PS I (at least 15 proteins) is adapted to bind light-harvesting membrane proteins. The PS I of Glaukophyta and Rhodophyta is slightly different from green plants. Various hypotheses about the evolutionary origin of PS I exist. The last common ancestor of all PSs probably shared features of both Type I and Type II. The purpose and the origin of a PS I heterodimer is also discussed in this work. A further understanding of PS I evolutionary history would be helped by...
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Expression of candidate genes for prostate cancer
Krupicová, Daniela ; Mareš, Jaroslav (advisor) ; Holá, Dana (referee)
4 Abstract Prostate cancer is one of the major medical problems within the male population in the Czech Republic and in the world. It is on second place among cancer illnesses with respect to mortality in czech male population. Its incidence strongly increases with age. Prostate cells have a unique ability to accumulate zinc in high concentrations compared to other tissues of human body. It is necessary for the proper physiological function of the prostate. There was detected loss of this accumulation ability in prostate cancer cells, which seems to be a condition to carcinogenesis in prostate cells. In this thesis was investigated the expression of four genes involved in the maintenance of homeostasis of zinc in prostate cells. Genes ZIP1 and ZIP7 encode zinc transporters, genes MT1-F and MT2 encode metallothioneins. There was collected 90 biopsy specimens from patients with prostate cancer or with benign prostatic hyperplasia. mRNA was isolated from these samples, cDNA was obtained by RT-PCR. This cDNA was detected by gel electrophoresis and the results were statistically evaluated. Several correlations was found between gene expression and the clinical data of patients. The most important result, there was found lower levels of expression of genes MT1- F and ZIP1 in samples of patients with cancer...
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Analysis of parameters presumably associated with drought-resistance in various sorghum genotypes
Panchártek, Daniel ; Holá, Dana (advisor) ; Hniličková, Helena (referee)
The aims of this work were 1) to assess whether sorghum (Sorghum bicolor (L.) Moench) genotypes originating from the India can be grown and analyzed in the climatic conditions of central Europe and 2) to find out the utilization potential of selected non- destructive and destructive methods based mostly on the chlorophyll a fluorescence measurements and the determination of photosynthetic pigments' content for the differentiation of sorghum genotypes based on their presumed drought tolerance. Field experiments made during 2 years compared 15 genotypes of this species (2 stay-green parental lines, 2 senescent parental lines and 11 introgression lines with stay-green loci), 2 of these genotypes were further analyzed in greenhouse conditions where the water deficit was induced by a cessation of watering for 12 days. The field-grown plants showed some differences between individual genotypes in all measured parameters; however, for the majority of the genotypes these differences were not statistically significant. The stay-green parental genotype B35 differred the most from the other ones in both field seasons, but the other stay-green genotypes usually did not differ from the senescent genotypes. No significant differences between both greenhouse-tested genotypes (presumably contrasting in their...
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Transcriptional regulation of PIN4 protein, membrane transporter of plant hormone auxin.
Hurný, Andrej ; Petrášek, Jan (advisor) ; Holá, Dana (referee)
PIN-FORMED (PIN) proteins are plant-specific secondary transporters acting in the efflux of plant signaling molecule auxin from cells. Their asymmetrical localization within cells determines the directionality of auxin flow and thereby influences plant development. The activity of PIN proteins is regulated at multiple levels; however the primary step in the regulation of PIN proteins takes place at the level of gene transcription. Therefore the main focus of this diploma thesis is the characterization of the transcriptional regulation of PIN proteins, namely PIN4 protein. The observation of plants carrying transcriptional fusion consisting of various lengths of PIN4 promoter and green fluorescent protein (GFP) showed which part of PIN4 promoter is essential for binding transcription factors and for the start of transcription. This part of PIN4 promoter was used as bait for transcription factors in yeast one hybrid screens. Altogether, 24 transcription factors were identified in which the most numerous were transcription factors from GATA and APETALA2 (AP2)/ETHYLENE RESPONSE FACTOR (ERF) families. To verify the interactions between identified transcription factors and PIN4 promoter, the protoplast transient expression assay was used. Protoplasts isolated from Arabidopsis thaliana leaves and tobacco BY-2 cell...
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Impact of the rRNA modifications on protein synthesis
Kročová, Eliška ; Pospíšek, Martin (advisor) ; Holá, Dana (referee)
A ribosome is a supramolecular structure, which mediates synthesis of all cellular proteins, and therefore is essential for cell life. The fact, that some nucleotides of ribosomal RNA are modified, is known for forty years. However only recently, successful deeper studies on how the individual modifications are synthesized and what is their effect on ribosome synthesis and function appear. Some particular nucleotide modifications are important for the ribosome formation (like m1 acp3 Ψ1191 SSU), some others influence proper function of the ribosome (e.g. Um2921, Gm2922, Ψ2923 LSU, m1 acp3 Ψ1191 SSU). Majority of modified nucleotides in eukaryotic rRNA is being recognized by small nucleolar RNA (snoRNA). Few nucleotides is, however, recognized and subsequently modified by specific proteins. These proteins also play crucial role in ribosome maturation. In thesis presented, current knowledge on the role of ribosomal RNA nucleotide modifications during their formation and maturation, and on their function is summarized and overviewed.
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Cis and trans elements in plant response to drought (with a particular focus on photosynthetic genes)
Panchártek, Daniel ; Holá, Dana (advisor) ; Feketová, Zuzana (referee)
Abiotic stresses, such as drought, high salinity and cold can strongly affect plant development and growth. Cis and trans elements are one of the options how plants regulate their own metabolism in those cases. That's the way how the expression of many target genes is induced. The products of these genes function not only in stress tolerance but also in general stress response. Many transcription factors and regulatory proteins (trans elements) are involved in these adaptions; those often interact with specific sequences in gene promoters (cis elements). Recenly, a progress has been made in analyzing the signal paths and complex cascades of gene expression regulation, although a little is still known about this regulation during drought conditions. Some of these target genes code products participating in photosyntesis and the regulation of their expression can significantly affect this process. This essay briefly describes main cis and trans elements of plant response to drought (with a particular focus on the regulation of photosyntetic genes). Keywords: drought, gene expression, cis-element, transcription factor, abcisic acid, photosyntesis, promoter.
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Molecular cytogenetic analysis of marker chromosomes and related abnormalities
Semanko, Adam ; Kočárek, Eduard (advisor) ; Holá, Dana (referee)
The primary focus of this diploma thesis is on marker chromosomes and phenotypically similar human karyotype polymorphisms, variants of short acrocentric arms in particular. The first half provides a very useful review of literature concerning different aspects of both sSMC and human polymorphisms such as their origin, inheritance, associated phenotype, formation and molecular cytogenetic methods that are applied in the process of identification of these aberrations. The methodical emphasis is on FISH and its modifications (e.g. M-FISH, acro M FISH, cen M-FISH) as well as on the CGH methods. The main objective was to test the above-mentioned methods and state their limitations and applications. Thus, in the other half we provide evaluations of commonly used methods and introduce new strategies that could be implemented to make the identification of these additional chromosomes or satellite translocations more effective. All the conclusions are based on the analysis of 7 patients with sSMC and 4 patients with variants involving acrocentric NOR regions. The results of our thorough research into their karyotypes have been compared with similar findings in the literature. Last but not least, we tried to establish a link between observed abnormalities and the type of a chromosomal aberration at hand.
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Inter- and intraspecific variability in Vicia faba L. and Zea mays L. response to water deficit
Fridrichová, Lenka ; Holá, Dana (advisor) ; Zelenková, Sylva (referee)
This work monitors the response of plants to water deficit and subsequent restoration of water availability with the aim to expand our knowledge about plant behaviour during and after drought stress from the perspective of two plant species with a different type of photosynthesis. A particular attention was paid to the intraspecific differences and their possible changes during stress and post-stress periods. The plant response was monitored as the changes of selected photosynthetic, morphological and developmental characteristics caused by the cessation of watering for six days followed by a six-day period of renewed optimal water supply. The experiments were carried out on plants with different types of photosynthesis - C3 plant Vicia faba L and C4 plant Zea mays L.; for both plant species, three varieties / genotypes were monitored. The response of both plant species to insufficient water supply differed by the extent of changes in relative water content (RWC), chlorophyll fluorescence parameters, the dry mass of individual leaves (developed during the stress period), the ratio between the aboveground dry mass and dry mass of roots. In drought-stressed plants, downward trend in RWC was observed, as well as the increase of the minimum yield of chlorophyll fluorescence in dark-adapted leaves (F ),...
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