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Preparation and characterization of diamond-based nanocarriers for transfection of siRNA
Majer, Jan ; Cígler, Petr (advisor) ; Fišer, Radovan (referee)
Although nanodiamonds were discovered and produced tens of years ago, they have been utilized in medical and biological fields just recently, particularly in drug and gene delivery into a cell and in bioimaging methods. Nanodiamonds can be modified with specific positively charged moieties for complexation with negatively charged nucleic acids. These complexes afterwards overcome extracellular and intracellular barriers and transport the nucleic acid either into cytosol or into the nucleus. Owing to fluorescence centres nitrogen- vacancy, which can be formed in the nanodiamonds, nanodiamonds exhibit excelling optical properties, as they emit stable fluorescence without "photoblinking" or "photobleaching". This thesis reviews properties, synthesis and modifications of nanodiamonds and other selected nanoparticles and their in vitro applications. This thesis also compares their cytotoxicity and gene knockdown efficiency.
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Mechanisms and aplications of macromolecule translocation across membranes of eukaryotic cells by bacterial toxins
Poledňák, Jan ; Fišer, Radovan (advisor) ; Žáčková Suchanová, Jiřina (referee)
Toxin translocation across the cytoplasmic membrane of the eukaryotic cell is a potent virulence factor of bacteria causing disease to eukaryotic organisms. Toxins translocate their domains responsible for the toxic activity inside the cell or create pores in cell membrane allowing the transmembrane traffic of ions, DNA, RNA or proteins. Knowledge of the toxin translocation process enables to characterize the mechanism and also the properties of the pore-forming toxin. Some of these toxins have been described in such a detail that were changed using site-directed mutagenesis and can serve as tools for characterization of the translocated molecules. One of such examples is the transfer of nucleotides or the whole nucleic acid molecules across the membrane through the pore of S. aureus α-hemolysine. Nowadays, this application is commercially used for DNA sequencing. Keywords: translocation, bacterial toxins, plasmatic membrane, nanopore sequencing
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The Shared Steps of Lincomycine and Pyrrolo-benzodiazepine Biosynthetic Pathways.
Jiráčková, Petra ; Janata, Jiří (advisor) ; Fišer, Radovan (referee)
Lincomycin and its semi-synthetic derivate clindamycin are therapeutically used antibiotics inhibiting protein synthesis in sensitive bacteria. Their structure is composed of an amino-sugar and an amino-acid moiety, which are linked with an amide bond. Some time ago the sequence of lincomycin-production gene cluster was established and functions of the most proteins coded from gene cluster were proposed on the basis of a comparison with known proteins and gene-inactivations. For a long time it was clear that the amino-acid moiety of linkomycin (propylproline) is related to a dihydropyrrol moiety of pyrrolo[1,4]benzodiazepine (PBD). Both of these moieties are derived from L-tyrosine and they undergo the same biosynthetic pathway at first. But other biosynthetic steps divide. It is believed that a transfer of genes from the PBD-production gene cluster to the lincomycin-production gene cluster could modify the structure of propylproline and improve traits of lincomycin e.g. increase antimalaric effects. The most effective antibiotics are alkyl derivatives, their chemical synthesis is very complicated, but they could be prepared via genetic engineering as so-called hybrid antibiotics.
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Confidence, economy and the global economic crisis
Fišer, Radovan ; Horváth, Roman (advisor) ; Benáček, Vladimír (referee)
We examine the role of confidence in economic fluctuations. Empirically we examine Granger causality from consumer confidence indicator to growth of economic output in the Czech Republic and the United States. In case of the U.S., we confirmed the causality robustly. In case of the Czech Republic, we found the causality, but not a robust one. Generally, the causality is taken as evidence for macroeconomic models with shocks to consumers's expectations. Recently, these models with unique-equilibrium gain on importance in economic theory. The second focus of this study is the confidence-related part of the financial and economic crisis of late 2000s which made confidence indicators hit record lows. Confidence has been cited as both a source of the crisis and the remedy to the crisis. We analyze such thoughts. One of the main ones is the incorporation of animal spirits into mainstream economomics.
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Inducible expression systems and their use in the study of parasitic organisms.
Horáčková, Vendula ; Doležal, Pavel (advisor) ; Fišer, Radovan (referee)
1 Abstract Inducible expression systems are systems with ability to switch expression of genes of interest on and off. Therefore, they are useful molecular tools for analysis of gene function. Nowadays, there are tens of various inducible expression systems available that differ from each other in level of regulation of gene expression, time of induction, possibilities of use, etc. This work is focused on three of them to illustrate common features of the inducible expression systems which regulate gene expression at the level of transcription. Firstly, systems based on regulation of lactose operon of Escherichia coli are mentioned. Secondly, systems which use regulatory elements of tetracycline resistance-encoding transposon Tn10 of E. coli are described. Third chapter is focused on systems regulated by agonists of ecdysone receptor. In the last chapter cases of use of inducible expression systems in the study of parasitic organisms are summarized.
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The effect of aminoacid variability on the resistance phenotype in ARE subfamily of ABC proteins
Lenart, Jakub ; Balíková Novotná, Gabriela (advisor) ; Fišer, Radovan (referee)
ARE subfamily proteins belonging to ABC transporters confers a different degree of resistance to macrolides, linkosamides and streptogramins antibiotics. Among the most clinically ARE subfamily proteins in staphylococci is Vga(A) protein lead to the award resistance to streptogtramins A. In 2006, discovered the new variant called the Vga(A)LC, which in addition to streptogramins A resistance also confers linkosamides. Vga(A) and Vga(A)LC differ in only 7 amino acids, yet confer different resistance phenotypes. In previous experiments it was found that the central role in determining substrate specificity play a 4 amino acid differences that accumulate in the section of 15 amino acids within the linker connecting the two ABC domains (positions 212, 219, 220 and 226). The combination of amino acids LGAG Vga(A) increases resistance to streptogramins A while present in combination SVTS Vga(A)LC increased resistance to linkosamides. Although in this subfamily includes a large number of resistance proteins, the mechanism of resistance has not yet been established with certainty. The aim was to create a new Vga(A) variants that contain specific combinations of amino acids for Vga(A) and Vga(A)LC protein at positions 212, 219, 220 and 226 and compared their ability to grant resistance to linkosamides. We also...
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Dependence of porin and beta-lactamases gene expression on the innoculum size of Klebsiella pneumoniae during the beta-lactam antibiotic treatment
Hepnar, David ; Žemličková, Helena (advisor) ; Fišer, Radovan (referee)
Gene expression of porin and beta-lactamases genes during the beta-lactam antibiotic treatment and effect of inoculum size on Klebsiella pneumoniae clinical isolates ABSTRACT In recent years, Klebsiella pneumoniae has been increasingly reported to be one of the most important nosocomial pathogens, and it is usually resistant to many antibiotics. In this work, we focused on the expression of the AmpC group β- lactamase DHA-1 and its negative regulator AmpR, as well as the porins OmpK35 and OmpK36 and on effect of inoculum. We used well-characterized Klebsiella pneumoniae strains in this study. Plasmids obtained from these strains were also transformed into different wild-type Klebsiella pneumoniae strains, which were typed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Gene expression analysis was performed by RT-PCR using specific primers and TaqMan probes. In most strains, expression was dependent on the presence of an inducer. The highly resistant strain showed a different expression pattern, but the expression of blaDHA-1 remained inducible by cefoxitin. Different regulation was also observed in the transformants. Based on our data, we suggest that the previously described regulatory pathway for AmpC is not generally suitable, and we propose that there are more...
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Topology and function of the transmembrane domain of colicin U produced by Shigella boydii
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Krůšek, Jan (referee)
Colicin U is a protein produced by strains of bacterium Shigella boydii. It exhibits antibacterial activity against some bacterial strains Shigella and Escherichia. Based on sequence homology with colicins A, B and N, the colicin U is classified as a pore-forming colicin. Interaction of colicin U with attacked bacteria is ensured by three-step mechanism: 1) First colicin U interacts with surface receptors OmpA, OmpF and core of LPS. 2) Thereafter the colicin is translocated to periplasm through interaction with Tol proteins. 3) Finally colicin U interacts with the inner membrane of the attacked bacteria causing its depolarization. In this thesis I demonstrated pore-forming features of colicin U and further observed characteristics and properties of these pores. Using methods of measuring on black lipid membranes I determined a single channel conductance (19 pS), ion selectivity, the influence of various conditions on the behaviour of the pores. These findings, in many cases, correspond to the findings on other related colicins. Furthermore, I successfully determined the pore diameter of colicin U ( ≈ 0,8 nm). The next section of the thesis focuses on creation of single cysteine mutations of colicin U. Subsequently I produced five mutant variants of colicin U and verified their functionality so that...
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