|
|
Evolution of silica structures in SAR protists
Čížková, Natálie ; Čertnerová, Dora (advisor) ; Kulichová, Jana (referee)
Silicon is an important element in the earth's crust. In nature it mainly occurs in the form of silicic acid. This element is used by marine and freshwater organisms to form their siliceous structures. The organisms that make up these structures are located throughout the phylogenetic tree and are not limited just to protist groups. The SAR line includes Stramenopila, Alveolata and Rhizaria. The main protist taxa forming the mentioned siliceous structures are in these groups. These are mainly diatoms, silicoflagellates, radiolarians and the group chrysophyceae. The formation of siliceous structures usually provides evolutionary benefits to organisms, such as protection of the cell from actions of biotic and abiotic factors. The availability of dissolved silicon changed during evolution, thus affecting the appearance and functionality of the structures of individual species. Structural changes were manifested by thinning of the shells, change of cell size, enlargement or decrease of pores, increase of the number of thorns or, conversely, their loss. The individual lines thus had to choose the best possible strategies in response to the decreasing availability of silicic acid. Therefore, there was frequent competition between the groups for the remaining dissolved silicon. The current diversity of...
|
|
|
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
|
|
|
Ecology and Taxonomy of limno-terrestrial diatoms from East Antarctica.
Bishop, Jordan ; Kopalová, Kateřina (advisor) ; Hutňan Chattová, Barbora (referee) ; Jüttner, Ingrid (referee)
Diatoms are single-celled photosynthetic eukaryotes that substantially contribute to global primary productivity. They are also among the most diverse groups of organisms in Antarctica. Biogeographically, Antarctica is divided into three distinct regions including the Sub-Antarctic, Maritime Antarctic, and Continental Antarctic. Recent taxonomic revisions of diatoms within the Sub-Antarctic and Maritime Antarctic Regions have uncovered a number of endemic taxa initially misidentified as cosmopolitan due to species "force-fitting". Within Continental Antarctica, this taxonomic uncertainty has led to confusion about the environmental drivers of limno-terrestrial diatom communities, although this knowledge is important given the use of diatoms as regional bioindicators for environmental change. The purpose of this dissertation is to reevaluate the diatom flora of Continental Antarctica and determine variables that structure their communities within two historically and biologically important localities within East Antarctica; the Vestfold Hills and Windmill Islands. The erection of the genus Sabbea was performed to accommodate a long-misidentified species, Sabbea adminensis, that occurs within the Vestfold Hills and McMurdo Sound Region where it had been the source of taxonomic confusion since the...
|
|
|
The diversity of diatom genera: relationship to genetic variability within the genus Frustulia and the role of geography
Vrbová, Kateřina ; Kulichová, Jana (advisor) ; Kopalová, Kateřina (referee)
The occurrence of some diatoms depends on degree of pollution and water quality. Due to this attribute are diatoms used as indicators for the environmental bioassessment. But the maximum use of diatoms for this purpose is complicated by high number of species which are defined based on the ultrastructural morphological features which are indistinguishable without the electron microscope. The aims of this study were to find out the influence of environmental factors, types of habitat and geography on the structure of diatom community. And find out if richness of higher taxonomic levels is correlated with species richness, in this case if it responds with the genetic diversity within diatom species complex Frustulia crassinervia-saxonica. In this study, 49 permanent slides from natural samples were analyzed. Samples were taken from benthos of different types of freshwater habitat - lakes, dams, pools, peat bogs, stream, wet wall on diverse localities in Europe, Canada, Greenland, Chile and New Zealand. In all slides were counted 300 cells which were determined based on the morphological features on genera level. Altogether 43 benthic genera were identified. The results of this thesis showed that number of genera correlated with pH gradient but do not correlate with other environmental factors -...
|
|
|
Floristicko-ekologický průzkum rozsivek Úslavy
HRUBÝ, František
This bachelor thesis deals with the issue of diatom based indices. The thesis describes the principles of 25 indices using diatoms to assess water quality. Seventeen of these indices were used to evaluate my own data originating from ten sampling points in the lower stream of the river Úslava. Periphyton communities of diatoms were collected in the autumn of 2015 and in the spring and summer of 2016. The diatom samples were used to create permanent slides, in which 400 valves were determined and counted. Using the Omnidia program, the indices were calculated for each sample. According to my results and information from literature appropriate and inappropriate indices for future use were chosen.
|
|
|
Biogeography and habitat preferences for genus Luticola
Hanišová, Lucie ; Kopalová, Kateřina (advisor) ; Kulichová, Jana (referee)
The genus Luticola is one of the most species rich group belonging to the diatom class (Bacillariophyceace) containing 204 described species. The aim of this work is to summarize the available literature on the genus Luticola concerning its biogeography, habitat preferences of polar and temperate species, and their ecological treshold for important factors relating and forming their presence - pH and conductivity. Records suggest that the Luticola genus is presence worldwide, with higher species diversity in Europe, South America and the Antarctic region, the latter of which harbors a substantial amount of endemic species. In terms of habitat preference, records suggest that temperate species occur mostly in aquatic habitats, while polar species occupy terrestrial environments. Polar species also differ from temperate species by occupying narrower margin of pH values. However, both groups prefer low conductivity, and most species of the genus Luticola are located in environments with values up to 100 μS/cm. Key words: biogeography, conductivity, Luticola, pH.
|
|
|
Palaeoecological reconstruction of Komořany Lake in Late Glacial based on diatom analysis
Poštulková, Anna ; Nedbalová, Linda (advisor) ; Tátosová, Jolana (referee)
Diatom analysis of basal part of profile PK-1-L contributes to multi-proxy research of former Lake Komořany. At this part of profile radiocarbon dating (dates sediments into Late Glacial and Early Holocene) and LOI (loss on ignition) had been conducted before, of which results have been utilized to more accurate interpretation of diatom analysis conclusions. Apart from diatom valves, presence of stomatocysts of Chrysophyceae has been observed. Having separated diatom valves from 32 sediment samples in intervals 0,4-0,6 cm, permanent preparates have been created. Concentration of valves in a gramme of dry sediment and relative abundance of diatom taxons in each sample have been investigated using light microscopy. In a half of samples subdominants and rare taxons have been observed separately to eliminate the interference from dominant taxons. Cluster analysis based on relative abundances of diatom taxons have been calculated and on its results have been subsequently determined three diatom accumulation zones (DAZ). Moreover trophic and saprobic indices have been calculated and levels of pH, conductivity and concentration of total phosphorus (TP) have been estimated by transfer functions. Even before beginning of Holocene the major shift in composition of diatom communities have happened, to the...
|
|
|
Diatoms of Quaternary Sediments from the Lake Komorany
Poštulková, Anna ; Rajdlová, Hana (advisor) ; Houfková, Petra (referee)
Diatoms are unicellular phototrophic organisms, whose siliceous frustules preserved in sediment have broad palaeolimnological application. Sediments of former Komořany Lake count among the richest Czech sediments in quaternary diatoms. This already destroyed locality is examinated in search and practical part of work. The search part contains characterization of diatoms and locality Komořany Lake. Diatoms are described in paleontological point of view, that is why the main attention is payed to morfology of frustule, their ecology and application in geological sciences. However, for complete image of this various group, the new pieces of knowledge about their taxonomy or evolution are not overlooked. The root of the work is summarization of accessible literature about Komořany Lake with special attention to research of diatoms. In practical part diatom valves were isolated from samples of sediment from profile PK-1-W, 18 long-lived sections were prepared and 6 of them were used for taxonomical determination. The 47 taxons of diatoms were found, 7 of them had not been included in work of Řeháková (1986). The synonymy of taxons are created in comparison with results of Řeháková (1986). From taken pictures are created 6 taxonomical plates. Key words: diatoms, Bacillariophyceae, Komořany Lake,...
|
|
|
Applications of diatom and chrysophyte silica structures in nanotechnologies
Burýšková, Barbora ; Němcová, Yvonne (advisor) ; Urbánková, Pavla (referee)
Diatoms and chrysophytes are single-celled organisms who have mastered the ability of controlling the biomineralization process. By incorporating silicon into their cell walls diatoms are able to create elaborate 3D silica structures with hierarchically ordered patterns and pores at the nano- to millimetre scale. In nature, diatoms inhabit almost all aqutic and aeroterrestrial environments. They play an important role in the global biogeochemichal silicon cycle and contribute significantly to oceanic primary production. The morphology of diatom cell walls (frustules) is species specific and the frustules exhibit unique photonic, optical and mechanical properties. There are more than 12 000 diatom species on earth, which represents the vast diversity of silica frustule shapes, applicable in nanotechnologies. However, only a few species have been used in experimental praxis so far. The cells of silicifying chrysophytes are covered with scales composed of the same material as the diatom frustules. The potentional use of chrysophyte silica scales in nanotechnologies is in the early stages of investigation. The aim of this bachelor's thesis is to recapitulate the findings on diatom and chrysophyte silica structures use in emerging nanotechnology applications, and to summarize published information on...
|
|
|
Diversity and relative biovolume of benthic diatom assemblages in relation to environmental conditions.
Šoljaková, Tereza ; Kulichová, Jana (advisor) ; Chattová, Barbora (referee)
iv ABSTRACT Benthic diatoms are due to a number of positive characteristics (such as high abundances, diversified communities, sensitive responses to environmental conditions, capturing long-term changes in the environmental conditions) currently the most commonly used bioindicators of the ecological status of freshwater ecosystems. However, due to problems associated with the use of traditional methods based on species composition (time-consuming identification, presence of species complexes, and requirements for calibration of water quality indexes for geographical regions) searching for alternative methods has been induced. The monitoring of the size structure of diverse diatom communities has been proposed as one of the methods. This approach would mainly eliminate the necessity of time-consuming determination of species. The main purpose of this thesis was therefore to determine the relationship between the size structure of benthic diatom communities, expressed as the relative biovolume, and selected environmental factors (pH, conductivity, habitat type) within freshwater lentic habitats. Furthermore, the variability of biovolume in dependence on environmental variables was compared with the change in species composition. If there would be a similar response pattern of both the biovolume and species...
|
guest ::
