National Repository of Grey Literature 78 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Temporal changes in the genetic and morphological diversity of silica-scaled chrysomonads (Stramenopiles, Chrysophyceae)
Tučková, Kateřina ; Škaloud, Pavel (advisor) ; Nedbalová, Linda (referee)
Temporal dynamics on short time scales is a very interesting area of research. Usually, temporal studies are done on a scale of months or years. However, microorganisms have a much shorter generation time and therefore changes can take place on a much smaller time scales. At the same time, almost none of the temporal studies go to the species level and mostly stay at the class level. That species dynamics change within days we know from observation, but this has never been properly verified. The genera Mallomonas and Synura from the class Chrysophyceae were chosen to study short-term temporal changes These two genera are characterized by the formation of siliceous scales on the surface of their cells, by which they are well morphologically identifiable to the species level. However, since species identification by microscopy is an old but traditional method, a new molecular method for species identification at the locality, i.e. metabarcoding, was also used. These two methods have been shown similar results for describing the golden algae community. At the same time, it was confirmed that temporal dynamics occur at the species level, but also at the section level in the genus Synura. Subsequently, it was possible to relate the environmental factors that cause temporal changes in the community to...
Biotechnological potential of algae and cyanobacteria from low temperature environments
Faško, Adam ; Nedbalová, Linda (advisor) ; Vítová, Milada (referee)
With the interest in biofuels rising, public awareness of the biotechnological potential of algae and cyanobacteria has grown and there is discussion about other possible uses of these microorganisms. Algae and cyanobacteria from low temperature environments possess exceptional properties as part of their adaptation strategies. The aim of this work is to evaluate whether these properties can be exploited in biotechnology. In my theses, I focus on the three most frequently discussed areas of application of algae and cyanobacteria from cold environments: production of polyunsaturated fatty acids, dyes and antioxidants, and wastewater treatment. Based on the available literature, I concluded that algae and cyanobacteria from low temperature environments can outperform mesophilic species in terms of production of desired substances or nutrient uptake from the medium under certain conditions. Selection of suitable strains, optimization of culture conditions and application of metabolic engineering and synthetic biology will have a major impact on the utilization rate of these microorganisms.
Detection of low chronic Pb concentrations by changes in structure of morphological plasticity of experimental desmid strains
Pilíková, Alena ; Neustupa, Jiří (advisor) ; Nedbalová, Linda (referee)
The lead is a metal toxic for organims and we don't know any biological function of it. It is bound as part of minerals in the earth's crust a it's not available for organisms. Secondarly it flows in environment from the sediment, where did it get by human historical activity, mainly in period after industrial revolution. In some conditions, primarly in environment with the low pH, it becames bioavailable for organims in water ecosystems. The green algae belonging to Desmidiales are known to be sensitive to presence of lead (Pb2+ ) in environment in comparison to other organisms. They could react to lower lead concentration by changes in cellular shapes, not by the loss of their viability. Based on a previous study focused on Micrasterias compereana I studied the effects of low chronical lead concentration on two unrelated desmid taxa. I choosed Micrasterias radians and Euastrum humeorsum as more and less phylogeneticaly related species to the previously studied M. compereana. Using biological shape analysis I tested sensitivity of changes in plasticity and cellular morphology to varying concentrations of lead in the environment. I asked if some of the studied species could be suitable for bioindication of the presence of dissolved lead in the environment. The results of my work showed that there...
Exploring the diversity of snow algae using polyphasic approach
Procházková, Lenka ; Nedbalová, Linda (advisor) ; Karsten, Ulf (referee) ; Hoham, Ronald (referee)
Snow algae cause blooms in slowly melting snowfields in mountain and polar regions. Although they are excellent models for the study of life in extremely cold environments, their taxonomical diversity, geographical distribution and variety of physiological strategies used to cope with their harsh environment are only partially understood. This work was focused on green algae from the order Chlamydomonadales and in one case on golden algae from the order Hibberdiales. An integrative approach was applied to characterise species, including the sequencing of several molecular markers (18S rDNA, ITS2 rDNA, rbcL) to reveal genotypes and infer phylogenetic positions. Light and electron microscopy were conducted to describe the detailed structure of cell wall surfaces and intracellular compartments. Moreover, fatty acid and pigment profiling were carried out to provide new insights into the adjustments of metabolic pathways in these algae. Rapid light curve measurements were used as a proxy of light preferences of photosystem II. Firstly, one of the main algae responsible for causing the phenomenon of red snow was shown to represent a single, monophyletic lineage, independent from other algae within the Chlamydomonadales (paper I). Therefore, the new genus Sanguina (S.) was described, with two...
Diversity of microalgae from extreme habitats: linking phylogeny and ecology
Barcyte, Dovile ; Nedbalová, Linda (advisor) ; Dvořák, Petr (referee) ; Bock, Christina (referee)
The diversity of microalgae from extreme habitats is far from being fully explored and understood. This is due, in part, to limited sampling efforts along with complex algal taxonomy and systematics. In particular, little investigated extremely acidic (pH < 3.0) and polar habitats might veil novel, undescribed species. This doctoral thesis aimed to study algal strains isolated from acidic or acidic and hot, and cold environments using a polyphasic approach. It focused on coccoid (Coccomyxa and Watanabea), monadoid (Chloromonas and its relatives) and saccoderm (Cylindrocystis) green microalgae from the classes Trebouxiophyceae, Chlorophyceae, and Zygnematophyceae, respectively. In addition, coccoid red algae (Galdieria) from the class Cyanidiophyceae were covered. The main research methods included light and transmission electron microscopy combined with Sanger sequencing. Nuclear 18S rDNA and plastid rbcL sequences were used for construction of phylogenetic trees for taxonomic position evaluation. Comparisons of secondary structure models of the highly variable ITS2 rDNA molecular marker served for a more detailed genetic relationship estimation among close relatives. Results have shown that Coccomyxa and Watanabea are present in extremely acidic lakes and that acidity and increased availability of...
Variability in extracellular phosphatase activity of dominant phytoplankton species in the Bohemian Forest lakes
Novotná, Jana ; Nedbalová, Linda (advisor) ; Rulík, Martin (referee)
Phosphorus (P) is considered as the most frequently limiting factor for phytoplankton growth in freshwater environments. One of the ways, how to solve the lack of P in algae and cyanobacteria, is the production of extracellular phosphatases. Extracellular phosphatase activity (PA) of phytoplankton at the single cell level was investigated in three acidified mountain lakes - Čertovo, Prášilské and Plešné in the Bohemian Forest (Czech Republic) from May to September 2007. PA of phytoplankton was detected directly at the site of enzyme activity using the fluorescence labelled enzyme activity technique (FLEA) and epifluorescence microscopy. The FLEA technique is based on colourless substrate ELF phosphate (ELFP) that is converted by enzymatic hydrolysis to the insoluble fluorescent product ELF alcohol (ELFA), which marks the site of PA. This thesis is divided into two parts. The first part (in Czech) is aimed at a general comparison of PA of phytoplankton in the three Bohemian Forest lakes. PA was characteristic for dinoflagellates Gymnodinium uberrimum, Gymnodinium sp. and Peridinium umbonatum that were ELFA labelled in all lakes almost during the whole season. Other species (e.g. Carteria sp., Chlorogonium fusiforme or Synura sp.) were active either in only one of lakes or in some samples. PA was...
Cold adaptation of snow algae: the role of changes in the composition of fatty acids
Dřízhalová, Marie ; Nedbalová, Linda (advisor) ; Němcová, Yvonne (referee)
Snow algae as typical extremophiles are good model organisms for study of adaptation for life on the boundary of physiological possibilities. So far, it is not clear, how these microorganisms ensure on the molecular level the optimization of photosynthetic processes in conditions around 0 řC, often with very high light intensity. The aim of this work was to find out light and temperature growth optima of two less studied strains and to assess the composition of fatty acids in selected psychrophilic and psychrotrophic strains from the genera Chloromonas and Chlamydomonas (Chlamydomonadales, Chlorophyta) from culture collections UTEX and CCCryo and collections in Europe including the Czech Republic and Slovakia. Using crossed gradients method, this thesis describes optimal temperature and light conditions of two strains of snow algae isolated from sites in the Krkonoše Mountains that are characterized by different ecological conditions. The strain Chloromonas reticulata Luční originates from alpine zone and according to its growth characteristics, it can be classified as psychrotrophic alga requiring high light. The second tested strain was Chloromonas pichinchae Meandry from forest environment, which is also characterized as psychrotrophic, In contrast to previous strain, it grows in a wide range of...
Diet quality impact on growth and survival of freshwater zooplankton species
Sýkorová, Veronika ; Sacherová, Veronika (advisor) ; Nedbalová, Linda (referee)
Food quality has a significant influence on freshwater zooplankon. It influences its growth rate and development generally. By quality we understand a certain stoichiometric ratio of the main biogenic elements (carbon, nitrogen, phosphorus) in the biomass of food. Ecological stechiometry is helping to understand the balance of chemical elements in ecological interactions and processes. Freshwater zooplankton consists mostly of two groups of organisms: rotifers (Rotifera) and crustaceans (Crustacea) - cladocerans (Cladocera) and copepods (Copepoda). Each of this groups requires different quality of food. Most of filtering cladocerans are fast- growing organisms, which need a phosphorus-rich food for their fast development (small C:P ratio in food) and vice versa for most of the copepods. The food offered is not always ideal for all members of zooplankton, that is why various pre- and post- absorptional mechanisms developed to help them to cope with unsuitable food. The ability to survive unvafourable conditions is closely linked to the zoolpankton's reactions to unsuitable C:N:P ratio in its food. The C:N:P ratio in food of zooplankton also influences the species distribution in water bodies. Key words: stoichiometry, food quality, zooplankton

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