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Raphidiopsis raciborskii - the main producer of cylindrospermopsin
Těšínská, Pavlína ; Němcová, Yvonne (advisor) ; Pichrtová, Martina (referee)
Raphidiopsis raciborskii is a globally widespread bloom producing cyanobacteria that has been observed more frequently in temperate freshwater locations in previous twenty years, which is a considerable expansion regarding its original occurrence in tropical regions. The ability to produce health-threatening toxins, cylindrospermopsin (CYN) and saxitoxin, places this species to the centre of scientific research. The goal of this bachelor's thesis is to sum up the current knowledge on Raphidiopsis raciborskii, concerning mainly its ecology and phytogeography, and also to provide information about cyanotoxin cylindrospermopsin, which can be produced by R. raciborskii and also by other cyanobacteria species. Regarding cylindrospermopsin, I mainly focused on the chemical structure of the molecule, its biosynthesis, toxicity, methods of CYN detection and removal from drinking water.
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Silicification of diatoms from a cellular, evolutional and ecological point of view
Šmída, Adam ; Kulichová, Jana (advisor) ; Němcová, Yvonne (referee)
Diatoms are a significant protist group. They've been getting a lot of attention because of their various silica cell walls since their discovery at the end of the 18th century. Even though the mechanism of the morphologically variable cell wall synthesis is well known in terms of shape and ornamentation, only recently it has been enabled to investigate the diatom silicification on the molecular basis. The knowledge of the silica cell wall synthesis can then be used to understand general acpects of biosilica handling and to enlighten the possible evolutionary substance and the progress of this phenomenon. Key words: biomineralisation, diatoms, long chain polyamins, nanostructure, silaffins, silica transporters, silica deposit vesicle, silicification
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Green algae of the family Halimedaceae and their role in the global ecosystem
Čečmanová, Adéla ; Neustupa, Jiří (advisor) ; Němcová, Yvonne (referee)
Species included in the family Halimedaceae are tropical and subtropical marine algae, belonging to Bryopsidales. The macroscopic siphonocladous thallus of these green algae is attached to the ground via holdfast. Segments of the thallus are able to store CaCO3, i.e. to calcificate. Consequently, dead segments of Halimeda are one of the major producers of seashore sediments. Thanks to beforementioned properties, these organisms play an important role in the global carbon cycle. Interestingly, the species of Halimedaceae are a great tool for studying the global climate change processes. Based on their strictly temperature-defined areas of occurrence in which they are able to grow and reproduce, we can easily observe the effect of increasing temperature of the seawater. Despite the significant role of Halimedaceae in marine ecosystems, these species have so far been relatively neglected in biological research. That was, amongst others, one of the main impulses for writing this thesis. Keywords: aragonite, calcification, ecology, green algae, Halimeda, sediment, segment, utricle
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Adaptation mechanisms to wide salinity gradient in algae; transitions between marine and freshwater environments in chrysophytes
Knotek, Petr ; Němcová, Yvonne (advisor) ; Pusztai, Martin (referee)
The transition from the marine to the freshwater environment and vice versa is a key event in the evolution of organisms. Although these transitions are relatively rare from an evolutionary point of view, most large groups of organisms have undergone this event at least once. The marine and freshwater environment differs in many aspects, especially salinity. During the transition between these two environments, the organisms are forced to overcome a significant salinity gradient and adapt to changes in the osmotic potential. However, biotic factors also play an important role, especially competition and predation in the new environment. The aim of the bachelor 's thesis is to provide comprehensive information on the mechanisms of adaptation to a wide gradient of salinity in algae in general and to focus on freshwater-marine transitions in chrysophytes, that occurred repeatedly and relatively frequently in the course of evolution. Key words: chrysophytes, Chrysophyceae, salinity gradient, osmoregulation, marine- freshwater transition
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Loss of excavate features in Excavata
Pavlátová, Magdaléna ; Čepička, Ivan (advisor) ; Němcová, Yvonne (referee)
Excavata is a supergroup of protists belonging to the Eukaryota domain. It is a very diverse taxon that comprises free-living organisms, commensals, and also parasits of animals and humans. Excavata is divided into two main lineages, Metamonada and Discoba, but from the morphological point of view the group Malawimonadida should belong here as well. The internal relationships as well as the monophyly of excavates have not been satisfactorily elucidated yet. The last common ancestor of excavates, perhaps even of all eukaryotes, had a ventral feeding groove, which was associated with a recurrent flagellum. This organism also possessed certain cytoskeletal structures that supported the ventral groove and vanes on the recurrent flagellum. These features have been preserved in some excavates to this day. However, the ventral groove has been reduced or lost in many lineages during the evolution and these representatives, which I refer to as non-excavate excavates, prevail. The aim of this thesis is to describe the ultrastructure of particular lineages of non-excavate excavates and to compare their cytoskeletal system with the cytoskeleton of typical excavates. The loss of excavate features in these lineages is discussed. Key words: excavate, non-excavate excavate, typical excavate, ultrastructure,...
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Methods for extraction and analysis of carotenoids and lipids in green alga Chromochloris zofingiensis (Sphaeropleales, Chlorophyceae)
Fajfrová, Terezie ; Němcová, Yvonne (advisor) ; Čabala, Radomír (referee)
Tato bakalářská práce se zabývá mikroskopickou zelenou řasou Chromochloris zofingiensis, jejím životním cyklem a morfologií. Chromochloris zofingiensis je zelená jednobuněčná řasa, která dokáže akumulovat velké množství karotenoidů a lipidů, proto se ukazuje jako zajímavá alternativa nynějších zdrojů těchto látek. Karotenoidy, především pak sekundární karotenoidy, jsou významné pro svoje silné antioxidační účinky a uplatňují se v akvakultuře, chovu drůbeže i farmacii. Akumulace lipidů, zejména neutrálních lipidů, značí potenciál pro výrobu biopaliv. Práce shrnuje využívanou metodiku pro stanovování karotenoidů a lipidů a různé způsoby kultivace pro maximalizaci jejich výtěžku. Zároveň se práce zabývá strukturou daných látek a jejich komerčním využitím. Ačkoliv se Chromochloris zofingiensis zatím komerčně nepěstuje, práce se snaží nastínit potenciální přednosti této řasy jako alternativního přírodního zdroje astaxanthinu, luteinu, canthaxanthinu a neutrálních lipidů.
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Silica-scaled chrysophytes in spatially structured microbiotopes (case study from Aquitaine; France)
Faturová, Jana ; Němcová, Yvonne (advisor) ; Čapková, Kateřina (referee)
In protists a biodiversity hotspot could be defined as region with exceptionally high ratio of local to global species diversity. In 2012 Aquitaine (France) was revealed to represent a hotspot of Synurales (lineage within silica-scaled chrysophytes). To investigate how the diversity is distributed and where the species are hidden, samples from 42 lakes were collected during spring peak of Chrysophyte occurrence (from March 27th to March 31st ). Samples were taken in two microbiotopes - phytoplankton and metaphyton. Metaphyton was represented by different substrates (aquatic plants). I identified seventy-six species from genera Mallomonas and Synura, which confirmed Aquitaine to be a hotspot. In this thesis, I investigated ecological drivers of chrysophytes diversity and community structure. The chrysophyte diversity was driven mostly by mutual impact of pH and conductivity, north-south gradient of lakes location and sampled microbiotopes. Number of identified species increased with increasing pH and conductivity, with increasing size of waterbody and with location of the lake more towards the South. More taxa were revealed from metaphyton (77) than from plankton (61), substrates played an important role. Lakes in Aquitaine are rich in different species of aquatic plant, which immersed create...
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Overview of phylogeny, systematics and diversity of genus Ulva (Ulvophyceae) and biotechnological use of these algae
Kantnerová, Veronika ; Neustupa, Jiří (advisor) ; Němcová, Yvonne (referee)
The genus Ulva represents a remarkable group of organisms, with number of species. It belongs to the class Ulvophyceae, one of the major groups of chlorophytic green algae and it is characterized by a typical dual morphology and isomorphic haplo-diplontic life cycle. This work is a summary of existing knowledge related to this algal genus with regard to the phylogeny, diversity and ecology, which is relatively interesting due to the ability of these algae to adapt to a wide range of abiotic conditions. It also focuses on the development of thallus morphology of these algae, especially with relation to an interesting and very important role of symbiotic bacteria in this process and, last but not least, on the biotechnological utilization that has great potential for the future, especially in terms of the utilization of Ulva as an alternative renewable energy source, a food supplement with high content of important proteins, minerals and vitamins, or as a source of polysaccharides, the so-called "ulvans", which are now investigated for their biological activity and application in human medicine. Key words: Ulva, Ulvophyceae, phylogeny, morphogenesis, biotechnology, ekology, diversity
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Biogeography and phenotypic plasticity in silica-scaled chrysophytes (Synurophyceae)
Škaloudová, Magda ; Němcová, Yvonne (advisor) ; Komárková, Jaroslava (referee) ; Kamenik, Christian (referee)
CONLUSIONS Results of the Papers 1 and 2 summarizing Mallomonas distribution rather support the"moderate endemicity model" of Foissner. The most of Mallomonas species were cosmopolitan or widely distributed, but we also found several species with geographically restricted occurrence contradicting the "ubiquity model". Besides two Asian endemics there are three Mallomonas species (M. multiunca, M. oviformis, and M. punctifera var. punctifera) not conforming to ubiquity model due to their highly nonrandom distribution in subtropic to subarctic zones of the Northern Hemisphere. Several others examples of Mallomonas species with restricted distribution are given in literature. Mallomonas kalinae was isolated and described from a peaty pool in North Bohemia (Paper 3). This strain together with the Synura curtispina strain was used for investigation of scale and bristle plasticity under different temperatures (Paper 4). Changes in morphology of silicate structures in relation to temperature were significant, although the large part of variability was caused by different position on the cell. Bristles become significantly shorter with increasing temperature. An inverse relationship between size of scales and temperature corresponding to the temperature-size rule was found. The main scale characters were stable...
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