National Repository of Grey Literature 77 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Green coenobial algae of the family Hydrodictyaceae, their phenotypic plasticity and use in ecology and paleoecology
Zavadilová, Kateřina ; Neustupa, Jiří (advisor) ; Knotek, Petr (referee)
Algae of the family Hydrodictyaceae attract our attention because of their unusual appearance. They belong to the order Sphaeropleales in the class Chlorophyceae. This family includes the coenobial algae, traditionally classified into the genus Pediastrum, which has recently been split into multiple genera based on the phylogenetic analyses. They are typically found in eutrophicated rivers, lakes and ponds. They form characteristic oval-shaped coenobia that may resemble tiny stars in their appearance. Their shape and size may be influenced by environmental factors such as pH or nutrients. Geometric morphometrics can also be helpful in detecting morphological variation or in refining the phylogenetic tree. The outer layer of the cell wall contains the polymer algaenan. Since algaenan is acid resistent, the cell wall remnants are preserved in the sediment. These cell wall remnants are found mainly in Tertiary freshwater sediments and their occurrence serves mainly as an indicator of eutrophicated conditions, for example in the context of anthropogenic eutrophication of lakes. The cell wall remnants could also be used for palaeolimnologic reconstruction. The thesis presented studies regarding their ekology, morphology, and associated phenotypic plasticity, and studies regarding their palaeobiological...
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...
"Plant hunting" in the Context of Science, Culture and Mentality in the 19th and Early 20th Century
Kocurek, Jakub ; Hermann, Tomáš (advisor) ; Neustupa, Jiří (referee) ; Stibral, Karel (referee)
This dissertation examines the phenomenon of 'plant-hunting' and 'plant-hunters' characteristic of Victorian and interwar Britain in particular. It defines and situates this phenomenon in time and space, and attempts to explain it. It primarily focuses on the questions of why the phenomenon arose in the given time and place, why and whether it disappeared at all, and whether it was eventually replaced by something and by what. It also examines what the existence of this phenomenon says about people's relationship to plants and the living world as such. The phenomenon is thus viewed through the plants sought by the plant-hunters themselves, and the plants are taken as the key to understanding the phenomenon. The work shows what distinguishes these particular plants from other plants. They are juxtaposed with the results of recent research on phytophilia, as well as with patterns in the more general human perception of the natural world. Furthermore, the work attempts to find appropriate functional-typological comprehensions, and places them within a theoretical explanatory framework. The whole phenomenon of plant-hunting is approached in the context of its era and contemporary science, technology, politics, and society.
Quantitative shape analysis of diatom frustules: asymmetry, allometry and morphospace structure
Woodard, Kateřina ; Neustupa, Jiří (advisor) ; Kleisner, Karel (referee) ; Lenarczyk, Joanna (referee)
This thesis is focused on geometric morphometrics of allometric and asymmetric variation in frustule shape of raphid pennate diatoms. While pronounced shape changes of diatom frustules related to their size reduction were many times reflected in diatom research, formal quantitative evaluation of these patterns has been rarely attempted. My thesis used semilandmark based geometric morphometrics of frustule outlines in analyses of morphological phenomena related to size reduction throughout mitotic phase of the life cycle, such as allometry, symmetry of frustules and their asymmetric deviations. The analyses showed that morphological allometry represents the dominant element of shape variation in several naviculoid species, such as Luticola poulickovae, Navicula cryptocephala, Sellaphora pupula. Shape changes during size reduction throughout the vegetative part of these taxa mostly involved a simultaneous increase in circularity of valve outlines and disparity among cells. On the other hand, asymmetry of valves proved to be unrelated to size changes within populations. However, the morphometric analyses of Luticola poulickovae revealed that there was a subtle but significant side-oriented asymmetry of valve outlines that is related to the position of the primary and secondary valve sides. In...
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...
Niche width of eukaryotic marine phytoplankton with respect to recent and future climate change.
Junková, Natálie ; Kulichová, Jana (advisor) ; Neustupa, Jiří (referee)
This paper describes the concept of niche breadth of photoautotrophic protists and attempts to introduce us to the basic concepts we may encounter when studying the ecological niche. The review clarifies what a niche is and its components fundamental and realized niche and presents some examples of organisms that are specialists or generalists. It uses diatoms, dinoflagellates and Haptophytes to describe how they can be affected by climate change. Since the number of environmental changes is steadily increasing, it is very difficult to predict the changes in the coexistence of generalists and specialists. The thesis presents some of the main methods used in measuring the width of the ecological niche of protists, which can be MaxEnt, ONE and the most frequently mentioned OMI (outlying mean index) method, which is described in more detail in the thesis. Given the focus of the thesis on photoautotrophic marine plankton, the most frequently mentioned organisms are diatoms, dinoflagellates and Haptophyta. Finally, I summarize the main ocean factors that could be affected by climate change, which are mainly pH, temperature, salinity or the amount of available nutrients (carbon, nitrogen, phosphorus, silicon and iron).
Micromorphology of segments in Halimeda tuna and their relation to calcium carbonate precipitation
Čečmanová, Adéla ; Neustupa, Jiří (advisor) ; Němcová, Yvonne (referee)
Algae of the genus Halimeda are important representatives of green algae, thanks to their ability to calcify. Calcification is the process of CaCO3 precipitation in the form of aragonite or calcite, which is then deposited on the bottom of the sea and thus participates in the formation of sedimentary rocks. Relatively small amount of information is known about calcification in representatives of the genus Halimeda, and in particular about its storage and distribution within the plant. One of the representatives of calcifying algae is Halimeda tuna living in the Mediterranean Sea, where it forms a significant part of the underwater vegetation. These algae have a thallus composed of segments, the internal structure of which is formed by utricles - a structure in which the aragonite is deposited. The aim of this work was to find out whether the different sizes of utricles within one segment have an effect on the subsequent spatial distribution of aragonite. The results showed that the distribution of aragonite microcrystals is not dependent on the size of the utricles - it is therefore equally spread across the segment. Furthermore, we investigated whether the calcification process would differ depending on the time of sampling during the year. From our data it appears that this process exhibits some...
Allometric diversity and plasticity of cellular morphologies of desmids (Desmidiales, Zygnematophyceae)
Mezník, Daniel Heliodor ; Neustupa, Jiří (advisor) ; Kleisner, Karel (referee)
If the proportions of two features of an organism change during its growth, their relationships can be described as allometry. The first partof this thesis quantifies the allometric relationship of semicellular perimeter and area of 11 species of unicellular microalgae from the genus Euastrum. These algae are recognized for their fractalmorphology, which is theorized to be an adaptation for increasing their surface area which is used to absorb nutrients.Thequestion was whether larger individuals within a population have a more complex shape and therefore a longer perimeter. I examined microphotographs of tens of semicells obtained from preserved wild populations. All included species exhibited a marked increase in shape complexity. The same trend could be noticed on and interspecific level. I compared these results to existing studies conducted on the related Micrasterias lineage. The second part of this thesis deals with allometric changes during semicells ontogeny in both Euastrum and Micrasterias. I analyzed growing clonal cultures using geometric morphometry. Specifically, I observed the relative position of 11 structurally homologous landmarks on semicells of different ages. This has been the first experiment of its kind on these model organisms. Idescribed theontogenetic change in landmark...

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