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Intracellular life of pathogenic bacterium Francisella tularensis in the host.
Rädisch, Robert ; Konopásek, Ivo (advisor) ; Vopálenská, Irena (referee)
Francisella tularensis is a facultative intracellular pathogenic bacterium, which causes disease named tularemia. For the entrance to the host cells Francisella uses host's cell mechanisms by which it is incorporated into cell phagosome. Subsequently, it escapes from phagosome to cytosole where bacterial growth takes place. Some of bacteria are cleared from cytosol by autophagy, from another ones dsDNA is released. This DNA is recognized by cytosolic receptors, which form inflammasome complex. Inflammasome sets off pathway leading to the death of infected cell. Since the penetration to the cell Francisella modulates cell signallization in its own benefit to ensure enough time and nutrients for its growth. Francisella do not act only in the infected cells, where it reduces recognition of itself and clearance from cytosol, but it also induces secretion of factors, which moderate activation of adaptive immunity of the host. Key words: Francisella, tularemia, fagosome, inflammasome, autophagy, adaptive immunity
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Virulence factors of Bordetella pertussis
Držmíšek, Jakub ; Večerek, Branislav (advisor) ; Vopálenská, Irena (referee)
Bordetella pertusis is a Gram-negative, aerobic, non-spore-forming coccobacillus. Although it's strictly human pathogen, it's possible to infect other mammals at laboratory conditions. Transmission among hosts is mediated via respiratory tract droplets. Infection could be direct, host to host, alternatively by contaminated environment. Bordetella colonizes upper respiratory tract, wherefrom descends into lungs and causes disease known as whooping cough or pertussis leading to 195 000 deaths of 16 mil. incidences per year (according to WHO report from 2010). More than twenty years before, respectively to found pertussis toxin, that time intensively under examination, pertussis was marked as toxin-mediated disease. In the course of time, more other virulence factors were revealed, that could be divided into groups of adhesins, toxins and others. Adhesins are filamentous haemagglutinin, pertactin and fimbriae. Toxins include pertussis toxin, adenylate cyclase, tracheal cytotoxin, dermonecrotic toxin and lipopolysaccharide. Most of virulence factors are regulated by two component system Bvg. However, it is needed lots of other factors for successful infection as for example autotransporters or so called siderophores serving as iron acquisition from environment. Secretion of virulence factors is mediated by its...
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Differentiation of yeast colonies and development of new approaches to monitor oxygen and nutrient availability
Vopálenská, Irena ; Janderová, Blanka (advisor) ; Demnerová, Kateřina (referee) ; Pichová, Iva (referee)
Yeast Saccharomyces cerevisiae as an unicellular organism is one of the best-studied experimental organisms. It is an important model organism for the study of intracellular processes of eukaryotic cells. Yeasts are also social organisms with cell-to-cell communication able to form organized multicellular structures (colonies and biofilms). Yeast and other microorganisms in nature prefer to form colonies on solid substrates rather than to grow as "planktonic" single cells (Palková, 2004; Wimpenny, 2009). The yeast S. cerevisiae typically forms colonies, biofilms were described only rarely. Yeast colonies exhibit an organized morphological pattern characteristic of each particular yeast strain (Kocková-Kratochvílová, 1982). This work is focusing on morphology and differentiation of the S. cerevisiae colonies of common laboratory strains forming less structured colonies, and strains of the Σ1278b genetic background forming highly structured "fluffy" colonies. It shows that polarized budding pattern and especially cell ability to form aggregates enable development of structured morphology. During development of "fluffy" colonies two differently regulated events of dimorphic switch from yeast form to filamentous growth occur. One of these events is dependent on the surface glycoprotein, Flo11p flocculin. This...
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