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Cell inclusions in microscopic eukaryotes
Pilátová, Jana ; Schwarzerová, Kateřina (advisor) ; Gierlinger, Notburga (referee) ; Prášil, Ondřej (referee)
This thesis reports, for the first time, a systematic study identifying various cell inclusions across the broad diversity of all major eukaryotic supergroups. Raman microspectroscopy technique was employed as a powerful technique, which is becoming the method of the first choice for such studies. In Chapter 1, the spatial reconstruction of chloroplasts of the unicellular zygnematophyte Cylindrocystis sp. (Streptophyta) revealed "empty spaces" inside. Subsequent analysis showed massive accumulations of polyphosphate, which is not located in the cytoplasm as in other species, but inside the chloroplasts. This newly discovered ability of the zygnematophytes, a sister group of terrestrial plants, to accumulate polyphosphate leads us to speculate about a possible adaptation to extreme Arctic conditions or even a preadaptation leading to plant terrestrialization. Chapter 2 summarizes the serendipitous discovery of purine crystalline inclusions in dinoflagellates and other microalgae. Investigated dinoflagellate species comprised zooxanthellae, the endosymbionts of reef-building corals, and the species causing toxic algal blooms. Purine crystals were further shown to act as dynamic high-capacity nitrogen storage. To show how widespread purine inclusions are, a revision of crystalline inclusions in all...
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Fluorescenční kinetická mikroskopie: 2D zobrazování variabilní fluorescence chlorofylu jednotlivých buněk řas se spektrálním rozlišením
Prášil, Ondřej ; Šetlíková, Eva ; Veselka, D.
The fluorescence kinetic microscopy (FKM) provides new dimension in application of chlorophyll fluorescence techniques. It combines classical fluorescence microscopy with 2D kinetic detection systems. FKM allows to examine photosynthesis of individual algal cells or on the cellular level of macroscopic structures. FKM is well suited to study heterogeneity in photosynthetic response among individual cells in algal cultures or in natural mixed populations. Special microscopic chambers allow to maintain live cells under optimal conditions for several hours or days and to follow evolution of photosynthesis in individual cells during the course of their growth cycle. Recent technical developments have allowed to determine FKM fluorescence kinetic with spectral resolution
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Nízkoteplotní emisní spektroskopie v ekofyziologii fytoplanktonu
Prášil, Ondřej
Low temperature (77K) emission spectroscopy is standard techniques of photosynthesis research. Emission spectroscopy provides wealth of information about both photosystems, their pigment composition, relative activity and stoichiometry and has been successfully applied in stress physiology. In this talk I will discuss examples of the use of portable versions of spectrofluorometer. Specifically, I will show that 77K emission spectra of phytoplankton from oligotrophic HNLC areas of subtropical gyres contain information that can be used as marker of iron limitation and provide clues about mechanisms of observed high intrinsic fluorescence yield in these areas
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Zvýšená koncentrace CO2 zvýší fixaci dusíku a růst mořské sinice Trichodesmium IMS101
Levitan, O. ; Prášil, Ondřej ; Berman-Frank, I.
Anthropogenic increases in atmospheric pCO2 over the last century are accompanied by higher concentrations of CO2 (aq) in the surface oceans. These changes could influence aquatic primary production including cyanobacterial nitrogen-fixers via the coupling between photosynthesis and nitrogen-fixation. We hypothesized that elevated pCO2 levels may enhance nitrogen fixation and photosynthesis in the bloom-forming, diazotrophic, cyanobacterium Trichodesmium spp. that contributes greatly to primary production in the oligotrophic subtropical and tropical oceans. We acclimated cultures of Trichodesmium IMS101 to 3 pCO2s (pre-industrial -250 ppmv, current - 400, future -900 ppmv) and examined changes in morphology, photosynthesis, nitrogen fixation, and growth. High pCO2 enhanced growth, filament length and nitrogen fixation of Trichodesmium in comparison with both ambient and low pCO2 acclimated cultures
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Fotosyntetické cirkadiální rytmy u mořské rozsivky Thalassiosira weissflogii v podmínkách dostatku a nedostaku dusíku
Kasalický, Vojtěch ; Rottnerová, K. ; Sciandra, A. ; Babin, M. ; Prášil, Ondřej
T. weissflogii was grown under dynamic irradiance conditions (sinusoidal light-dark regime) and then switched to constant, low irradiance. Cellular characteristics (pigment and nutrient content, cell size) indicated synchronization of algal population, furthermore pronounced variations in the aktivity of variable fluorescence, thermoluminescence and in the gene expression (rbcL, psbA, fcp) were observed
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