National Repository of Grey Literature 8 records found  Search took 0.01 seconds. 
Separation and Elemental Composition of Tardigrades and Rotifers from Cryoconite in Svalbard
Jaroměřská, Tereza ; Žárský, Jakub (advisor) ; Šabacká, Marie (referee)
For years considered pristine, glacial ecosystems are attracting more attention of biologists from various branches in last decades. Moreover, they are currently considered to be ecosystems forming the coldest biome on the Earth. The life on glaciers ranges from viruses and bacteria to highest consumers such as few groups of microinvertebrates. The most common are tardigrades (phylum Tardigrada) and rotifers (phylum Rotifera) which inhabit cryoconite holes on the glacial surface. Several studies highlight the importance of the role of these consumers. However, due to the dominance of prokaryotes on the glacial surface, these microinvertebrates are usually out of the major scope of most studies aiming at biological processes. The present study shows pioneering results on the isotopic composition of tardigrades and rotifers, which are the top consumers in cryoconite ecosystems, and is a foundation for the exploration of trophic pathways and interactions within cryoconite holes using elemental and stable isotopic analyses. It also presents information about the species composition of tardigrades and rotifers on different glaciers and in different parts of the ablation zone. We identified 5 species of tardigrades (Hypsibius sp., Hypsibius cf. dujardini, Pilatobius sp., Isohypsibius sp. and Cryoconicus...
Ecology of microbial communities in the sulfidic ore environments
Falteisek, Lukáš ; Čepička, Ivan (advisor) ; Šabacká, Marie (referee) ; Mandl, Martin (referee)
1 Abstract This thesis is focused on the diversity of microorganisms of prokaryotic type living in the environments, where microbial sulfidic mineral precipitation or decomposition occur. The relationship between the microbial community composition and geochemical processes was examined. To the best of our knowledge, we were the first to analyze microbial communities from gossan and their significance for the ecosystem of a large sulfidic ore deposit. In addition, we compared the microbial assemblies at multiple habitats associated with generation or transformation of acidic mine drainage (AMD) and described niche partitioning among closely related organisms. The unexpectedly variable communities in stalactites growing on the AMD springs were utilized as a model for assessing neutral variability of the microbial communities. They clustered almost randomly even though the environmental conditions corresponded with the localities. This is an important difference of the simple communities from stalactites and the common highly diversified microbial assemblies. The communities found in sediments, soil, and many other complex substrates usually reveal high correlation with their environment. We propose that neutral fluctuations of the community composition are suppressed by averaging multiple physically...
The effect of climatic changes on genetic build-up of populations and their role in promoting adaptive radiations
Štefková Kašparová, Eva ; Janko, Karel (advisor) ; Šabacká, Marie (referee) ; Hulva, Pavel (referee)
The Southern Ocean and its enormously cold, remote and yet the wildest continent, the Antarctic, have experienced numerous rapid climatic changes. It used to be viewed as a barren wasteland with limited knowledge of species diversity or phylogeography. Recently, all aforementioned premises are being increasingly questioned, and this thesis aims to shed light on them. Firstly, multi-locus genetic markers were used to evaluate if it is the lifestyle, benthic or pelagic, including the duration of the pelagic larval period that determines the population connectivity of particular notothenioid species. It was the adult's fish lifestyle along with the oceanographic factors that are responsible for the gene flow between localities. Secondly, is lifestyle a factor determining the extent to which Pleistocene growing grounded ice sheet affected species past population dynamics? The attention was paid to Notothenioidea fish, then to Echinoidea sea urchins, and lastly to NCBI database available antarctic marine shelf and deep-sea fauna. Our findings suggest that the last glacial maximum affected more profoundly the population size of benthic shelf species. At the same time, those living in the water column or inhabiting deep slopes had more ancient population size changes. The Antarctic terrestrial evolution...
Genetic potential for methane metabolism in the Greenland subglacial ecosystem
Rybár, Marek ; Stibal, Marek (advisor) ; Šabacká, Marie (referee)
Subglacial environments, located at the interface of glacier ice and bedrock, represent one of the major ecosystems associated with glaciers and ice sheets. This environment contains liquid water and underlying sediment with large amounts of organic matter overridden during periods of ice advance. Large areas of subglacial sediment are exposed annually by glacier melting and retreat, which affects the subglacial carbon stores and may significantly impact regional carbon fluxes. Due to the widespread anoxia at glacier beds, subglacial environments are potential producers and reservoirs of methane that can be released into the atmosphere as a consequence of glacial retreat. While the presence of methanogens and methane oxidisers has been shown based on 16S rRNA gene data, no data on the functional genetic potential for methane metabolism currently exist. In this study, the first subglacial metagenomes obtained from subglacial sediment exported from beneath the Greenland ice sheet by a meltwater river were used to characterize the metabolic potential for methane metabolism by the identification and quantification of genes involved in methane production and consumption. Functional genes of potential syntrophic pathways were also investigated. Functional genes of methanogenesis/anaerobic oxidation of methane and...
Separation and Elemental Composition of Tardigrades and Rotifers from Cryoconite in Svalbard
Jaroměřská, Tereza ; Žárský, Jakub (advisor) ; Šabacká, Marie (referee)
For years considered pristine, glacial ecosystems are attracting more attention of biologists from various branches in last decades. Moreover, they are currently considered to be ecosystems forming the coldest biome on the Earth. The life on glaciers ranges from viruses and bacteria to highest consumers such as few groups of microinvertebrates. The most common are tardigrades (phylum Tardigrada) and rotifers (phylum Rotifera) which inhabit cryoconite holes on the glacial surface. Several studies highlight the importance of the role of these consumers. However, due to the dominance of prokaryotes on the glacial surface, these microinvertebrates are usually out of the major scope of most studies aiming at biological processes. The present study shows pioneering results on the isotopic composition of tardigrades and rotifers, which are the top consumers in cryoconite ecosystems, and is a foundation for the exploration of trophic pathways and interactions within cryoconite holes using elemental and stable isotopic analyses. It also presents information about the species composition of tardigrades and rotifers on different glaciers and in different parts of the ablation zone. We identified 5 species of tardigrades (Hypsibius sp., Hypsibius cf. dujardini, Pilatobius sp., Isohypsibius sp. and Cryoconicus...
The diversity of algae from red snow in Europe: combination of molecular and morphological data
Křížková, Heda ; Nedbalová, Linda (advisor) ; Šabacká, Marie (referee)
We can find a lot of microorganisms living in snow including psychrophilic snow algae from the order Chlamydomonadales (Chlorophyta). They are adapted to the extreme conditions in this habitat and can cause the phenomenon of coloured snow. The species Chlamydomonas nivalis (Bauer) Wille is the most commonly associated with red snow in alpine and polar regions during summer season worldwide. In the field material, we can find red spherical cells without flagella and any morphological characteristics suitable for species determination. Until now, this species has not been isolated into laboratory culture and its life cycle is unclear. Furthermore it has been shown that red coloured snow can be caused by more species which used to be determined as Chlamydomonas nivalis. The aim of this study was to collect samples of red snow from different parts of Europe, to describe the morphological variability of Chlamydomonas nivalis-like snow algae in relation to region of origin, to try to isolate laboratory strain of this species and to describe its position and distribution by phylogenetic analysis of laboratory strains and field samples. Red snow samples were collected from 30 European localities in Slovenian Alps, Romania, Dolomites, Ötztal, Wallis and Sarntal Alps, High Tauern, Ortler massif, in Norway,...
Ecology of microbial communities in the sulfidic ore environments
Falteisek, Lukáš ; Čepička, Ivan (advisor) ; Šabacká, Marie (referee) ; Mandl, Martin (referee)
1 Abstract This thesis is focused on the diversity of microorganisms of prokaryotic type living in the environments, where microbial sulfidic mineral precipitation or decomposition occur. The relationship between the microbial community composition and geochemical processes was examined. To the best of our knowledge, we were the first to analyze microbial communities from gossan and their significance for the ecosystem of a large sulfidic ore deposit. In addition, we compared the microbial assemblies at multiple habitats associated with generation or transformation of acidic mine drainage (AMD) and described niche partitioning among closely related organisms. The unexpectedly variable communities in stalactites growing on the AMD springs were utilized as a model for assessing neutral variability of the microbial communities. They clustered almost randomly even though the environmental conditions corresponded with the localities. This is an important difference of the simple communities from stalactites and the common highly diversified microbial assemblies. The communities found in sediments, soil, and many other complex substrates usually reveal high correlation with their environment. We propose that neutral fluctuations of the community composition are suppressed by averaging multiple physically...
Tolerance of pennate diatoms (Bacillariophyceae) to experimental freezing: comparison of polar and temperate strains
Hejduková, Eva ; Nedbalová, Linda (advisor) ; Šabacká, Marie (referee)
Environment in Polar Regions is characterized by many extremes. Low temperatures, lack of fluid water, irregular nutrient and light supply, fluctuations in daily and annual cycles could seem unfavourable for life. In spite of this, diatoms (Bacillariophyceae) are one of groups of microorganisms that apparently well adapted to such environment and dominate in a wide range of polar habitats. For many organisms, dormancy is a strategy to overcome unfriendly conditions, but morphologically distinct resting stages are observed rarely in diatoms. In this study, the tolerance of polar and temperate diatoms to freezing was experimentally tested and the difference in survivability of vegetative and resting cells was assessed. Diatom strains for the experiments were isolated in 2014 using natural samples from the Maritime Antarctica (James Ross Island, Vega Island) and the Arctic (Spitsbergen). Further strains were acquired from culture collections of microorganisms (CCCryo and BCCM). Resting cells were induced by incubation under nitrogen and light limitation in lower temperature. The vegetative and resting cells of 26 strains were exposed to six different freezing treatments (including those simulating natural conditions) to -4 řC, -20 řC, -40 řC and -180 řC (liquid nitrogen). Treatments differed also in...

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