National Repository of Grey Literature 54 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
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...
Biodiversity-productivity relationship in desmid communities
Škvorová, Marie ; Škaloud, Pavel (advisor) ; Nedbalová, Linda (referee)
This thesis deals with biodiversity-productivity relationship in desmid communities. Biodiversity is found to be changing globally. The biodiversity-productivity relationship is therefore an important research topic. Three aspects of biodiversity are thought to play an important role: species richness, functional diversity and phylogenetic diversity. It is known that in general, productivity is positively correlated with diversity. Interactions between different metrics of biodiversity are known less. Existing studies have shown that these interactions might be present. In general, biodiversity-productivity studies were mostly focused on plants. Less is known about other organisms, including algae. In this work I explore the relationship between overyielding and functional or phylogenetic diversity on a species richness gradient of desmid communities. I conducted an artificial biodiversity- ecosystem functioning experiment using combinations of two to 12 desmid species. Communities differed in the diversity aspects. I had measured the biomass growth. For the analysis, I have used the overyielding index, which is based on a comparison of a polyculture production with the production expected based on monoculture yields. The relationship of overyielding on functional diversity depended on species...
Impact of habitat type and long-term in vitro cultivation on photosynthetic characteristics of snow algae and their resistance to stress induced by UV radiation
Zázvorková, Michaela ; Nedbalová, Linda (advisor) ; Kvíderová, Jana (referee)
Snow algae are psychrophilic microorganisms, that inhabit snow fields in mountains and polar regions, which creates colored snow in good conditions. Most species belong to order Chlamydomonadales (Chlorophyta) with complicated life cycles, containing flagellates and immobile stages (cysts). Extreme environment of snow is characteristed by low temperature, problems with availability of water and lack of nutrition. Depending on location and phase of life cycle, snow algae have to deal with excess or lack of solar radiation, the important component of which is also dangerous UV radiation. The light conditions differ substantially from open location above the forest level or polar regions to forest habitats. In the first part of this work I compared reactions of photosynthetic apparatus of snow algae strains from forest and forestless habitats to different intensity of radiation, then I dealt with assessing any changes related to long-term cultivation in laboratory. Based on measurement of rapid light curves on PAM fluorometer I have determined some characteristics of photosynthetic apparatus of individual strains (parameters α and Ik), which indicate adaptation to low or high light intensity. For some strains, it was possible to compare the results obtained at a three-year interval. In the second part...
Ecological and taxonomic structure of subaerial biofilms of green algae on the needles of gymnospermous trees
Zelená, Radka ; Neustupa, Jiří (advisor) ; Nedbalová, Linda (referee)
Aero-terrestrial algae form distinct biofilms on different natural and man-made surfaces. Their taxonomic diversity is considerable, but not yet fully studied, even though recent attention has been paid to it. The study of the diversity of these algae is made more difficult by the morphological convergence of representatives of the most common class of Trebouxiophyceae, who most often form coccoid thalli. That is why molecular genetic methods are very often applied to study these algae. In addition to species diversity, the ecology of these algae communities, their spatial diversity, seasonality are also studied. In my work I focused on two aspects of microbial biofilms growing on the needles of the common yew. In the first study, I evaluated the amount of algae in biofilms on needles within the Prague urban ecosystem in relation to the air quality. This is the first study of this type on a small scale, showing that these biofilms could serve as bioindicators of air quality in urban areas, reflecting different concentrations of nitrogen oxides and particulate matter. In my second study I studied the taxonomic diversity of these biofilms in two European regions. So far no taxonomic study has been made from this specific habitat. We have recorded a relatively large amount of algal taxa despite the...
Freshwater green algae in polar regions: diversity, biogeography and methodology comparison
Šamšulová, Tereza ; Nedbalová, Linda (advisor) ; Chattová, Barbora (referee)
Green algae (Chlorophyta) are an important group of primary producers in polar regions, but they received less attention in comparison with cyanobacteria and diatoms. Environmental conditions of freshwater habitats in the Arctic and Antarctica (lakes, wetlands, streams, glaciers and snow) are very variable and microoganisms have to resist multiple extreme conditions. The overview of 58 green algal genera from polar regions showed the prevalence of representatives from the Chlorophyceae and Trebouxiophyceae, more genera were documented from the Arctic. Lakes have the highest and wetlands the lowest genus richness. This fact could be affected by uneven number of studies in both polar regions and from different habitats. The occurrence of several species has been documented only in Antarctica, but overall the green algae distribution is supposed to be rather ubiquitous. The traditional method of biodiversity research is light microscopy, which has limitations due to simple morphology of green algae. Their identificatiton at genus or species level is thus often possible only using molecular methods. While sequencing by Sanger method is used for determination of monospecific isolates, metagenome analysis allows the identification of non-cultivable or rare species. The use of combination of methods...
Phytoplankton in acidified lakes: structure, function and response to ecosystem recovery
Nedbalová, Linda ; Stuchlík, Evžen (advisor) ; Štefková, Elena (referee) ; Komárková, Jaroslava (referee)
Souhrn Předkládanáprácese zabývázejménaruznýmiaspektyeko|ogieplanktonuhorskýchjezer, kterése v současnostizotavujíz acidifikace. Následuje stručnýsouhm přiložených publikacís důrazemnafytoplankton. 1. Biologické zotavováníšumavských jezer z acidifikace (NEDBALoVÁ& al. 2006a) Tato práce se na záklaclě údajůzískanýchna podzim 2003 zatrtěÍilana podrobné vyhodnocenísoučasnéhostavuchemickéhoa biologickéhozotavováníosmi šumavských jezerz acidifikace.Ve srovnánís datyz roku 1999jiŽdošlove čtyřechjezerechk obnovení jejich uhličitanovéhopufračníhosystému(Kleiner ArberseeoPráši|ské,GrosserArbersee a Laka).Zbývajic|čtyřijezeravšakstálezůstávajíacidifikována(Černé,Čertovo,Rachelsee a Plešné).MnoŽstvía sloŽeníobjemověváŽenýchprůměrubiomasyplanktonuodráŽelo rozdíly v acidifikačnímstatutu a v přísunu Živin do jednotlivých jezer. Zal|mco bakterioplanktonbyl hlavní složkou biomasy v acidifikovanýchjezerech s výjimkou PleŠnéhojezer4 v zotavujícíchse jezerech dominoval fytoplanktonspolečněse zooplanktonem.PřevahaÍytoplanktonubyla charakteristickápro mezotrofníPlešnéjezero, kterése vyznačujevyššímpřisunemfosforu.Celkově lze shrnout.Že druhovésloŽení a mnoŽstvíbiomasyltoplanktonu vjednotlivýchjezerechbylo ovlivněnozejménarozdíly ve stupni jejich acidifikace, dostupnostiŽivin a charakteruzooplanktonu.Například příčinou vysokého...

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