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Microdomains in freshwater sediment as a driving factor in the biogeochemical processes
Duchoslav, Vojtěch ; Falteisek, Lukáš (advisor) ; Beranová, Jana (referee)
A natural arsenic anomaly at Mokrsko is a site of biogenic precipitation of realgar (As4S4) in stream sediment. The extent of the phenomenon in Mokrsko is globally unique. A previous study showed the ability of microorganisms to solubilize arsenic from its secondary minerals and to produce realgar precursors, i.e. sulfides and arsenites, by anaerobic respiration. The study also raised questions about the mechanism of realgar precipitation since physicochemical conditions favoring this reaction were never detected despite significant sampling efforts. We chemically and microbiologically analyzed sedimentary profiles to the depth of ca. 120 cm in order to understand the functioning of the biogeochemical system. The profiles comprised both the unsaturated and the saturated zone. We distinguished six different domains representing environments from the surface soil to anoxic sedimnent containing realgar-encrusted wood. An analysis of phylogenetic dissimilarity revealed that microbial communities from the various domains form distinct clusters. This suggests that different conditions prevail in the various domains, and that different biogeochemical processes take place there. Incubation (microcosm) experiments showed that bioprecipitation of realgar can be conducted in vitro. It requires a suppression...
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Application on nanoparticles in bio-medicine.
Bělinová, Tereza ; Hubálek Kalbáčová, Marie (advisor) ; Beranová, Jana (referee)
During last few years nanoparticles of different origin have been used in biomedicine. Their interactions with cells are however a big point of concern and so further research is needed to be done regarding their properties, internalization into cells and their fate within the cell. All of this is needed for correct selection of proper nanoparticles for bioimaging and also for future use in human medicine. One of the main parts of research is deep understanding of interactions of nanodiamonds and silicon based nanoparticles with cells, because of their highly unique properties (autofluorescence), biocompatibility and in case of silicon nanoparticles also their degradability.
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Cytoplasmic membrane of Bacillus subtilis Regulation of the physical parameters
Beranová, Jana ; Konopásek, Ivo (advisor) ; Branny, Pavel (referee) ; Holoubek, Aleš (referee)
Bacillus subtilis, a model Gram-positive soil bacterium, employs two distinct mechanisms in its membrane adaptation to low temperature: 1) Long-term adaptation to suboptimal temperature is accomplished by increasing the ratio of anteiso- to iso-branched fatty acids in the membrane lipids. 2) After a sudden temperature decrease, the oxygen-dependent fatty acid desaturase (Des) is induced which desaturates fatty-acyl chains incorporated in membrane lipids. The transcription of the gene encoding desaturase, des, is activated by the decrease of the membrane order, via two- component system DesK-DesR. In this work, I studied the influence of cultivation conditions on the mechanisms of B. subtilis membrane adjustments for a low temperature employing fatty acid analysis, fluorescence spectroscopy, differential scanning calorimetry and methods of molecular biology. In the first part of this work, I examined the impact of the cultivation medium on the composition and biophysical features of the B. subtilis cytoplasmic membrane during growth under the optimal (40 řC) and suboptimal (20 řC) cultivation temperature. I compared the nutrient-rich complex medium containing glucose and the mineral medium supplemented with either glucose or glycerol. The results obtained showed the crucial importance of medium...
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Long-term disturbance dynamics of spruce forest in High Tatra Mts.
Beranová, Jana ; Kuneš, Petr (advisor) ; Jamrichová, Eva (referee)
Spruce forest is an important production ecosystem for our civilization. Its development can be affected by three main types of disturbances: forest fire, windstorms and spruce bark beetle attack. Experiences with a massive and long-term attack of spruce bark beetle in the Šumava mountains and a strong windstorm in 2004 in the spruce forest in the High Tatra provoke questions, how natural are such severe disturbances. To understand the current development of forest ecosystems, it is necessary to study past structure of these forests and frequency of forest disturbances. This work is about locality Tatranská Lomnice located in the High Tatra mountains, in the belt of mountain spruce forest. In my work, I used mainly pollen and plant macro-fossils analyses. I compared my data with disturbance information originating from dendroecology for windstorms and from charcoal analysis for fires. My research found that according to the pollen assemblages, most of the disturbances did not have strong influence on the forest composition, and most likely they only caused the forest thinning. The most significant fire occurred around 1420. The most significant wind disturbance probably occurred in 1890. The was not found any effect of spruce bark beetle. In the past millennium disturbances affected spruce forest...
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