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Function of PsbO isoforms
Duchoslav, Miloš ; Fischer, Lukáš (vedoucí práce) ; Špunda, Vladimír (oponent) ; Sobotka, Roman (oponent)
(česká verze) Oxygenní fotosyntéza je zásadní pro většinu forem života na Zemi. Rozklad vody, při kterém se uvolňuje kyslík, je zajišťován fotosystémem II (PSII), pigment-proteinovým komplexem nacházejícím se v tylakoidní membráně chloroplastů. PsbO je jeho nepostradatelná podjednotka, která se váže na transmembránové podjednotky PSII z luminální strany. Hlavní funkcí PsbO je stabilizovat a chránit manganový klastr (Mn4CaO5), na kterém probíhá rozklad vody. Pravděpodobně má však i další, doplňkové funkce. Tyto doplňkové funkce mohou být rozdílné u izoforem proteinu PsbO, což bylo navrženo pro huseníček (Arabidopsis thaliana), který exprimuje dva geny kódující proteinové izoformy PsbO1 a PsbO2. Tato dizertační práce je zaměřena na doplňkové funkce PsbO s důrazem na rozdíly mezi izoformami. Analýzou sekvencí psbO jsme zjistili, že kromě huseníčku exprimuje dva geny psbO i mnoho dalších druhů rostlin. Zajímavé je, že duplikace genu psbO proběhla mnohokrát nezávisle, typicky ve společném předkovi současných čeledí krytosemenných rostlin. Nicméně izoformy PsbO se přesto liší na podobných místech struktury. To naznačuje, že u PsbO mohlo proběhnout paralelně u různých linií podobné rozrůznění funkcí. Biochemická charakterizace PsbO ze zelené řasy Chlamydomonas reinhardtii a dvou izoforem PsbO z bramboru...
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Automated eddy covariance data quality control for long-term measurements
Šigut, Ladislav ; Mauder, M. ; Sedlák, Pavel ; Pavelka, Marian ; Špunda, Vladimír
Estimation of matter and energy exchange using the eddy covariance method is often organized into regional or global networks. To achieve comparability among sites, it is important to standardize and specify the methodology used. Currently, quality control (QC) is one of the most time-demanding steps in data processing within the Czech Carbon Observation System. Although manual QC (MQC) enables consideration of more complex test applications, it is often difficult to document. The aim of this study was to establish an automated QC (AQC) scheme based on available literature and post-processing software and test its effectivity and reliability on sites comprising an agroecosystem and a mature European beech forest. AQC successfully flagged low-quality CO2 fluxes and provided estimates of net ecosystem productivity similar to estimates based on MQC. The tests’ efficiency was particularly high for the agroecosystem, where AQC removed 13% less data than did MQC. We conclude that the adopted AQC displays satisfactory performance, especially for sites with low canopy heights.
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CN-PAGE as a tool for separating pigment–protein complexes and studying their thermal stability in spruce and barley thylakoid membranes
Kurasová, Irena ; Svrčinová, K. ; Karlický, Václav ; Špunda, Vladimír
The central aim of our study was to develop a method for solubilization and native electrophoretic (colourless native polyacrylamide gel electrophoresis; CN-PAGE) separation of pigment–protein complexes (PPCs) embedded in thylakoid membranes (tBMs) isolated from spruce. Subsequently, we focused on studying the effect of temperature on the composition and PPC stability of two different species: barley and spruce. We found that the mild detergent n-dodecyl β-D-maltoside (β-DM) is suitable for PPC solubilization of spruce tBMs, but longer solubilization and a higher ratio of detergent to total chlorophyll are needed for spruce than are needed for barley. We also unified CN-PAGE protocols to optimize the separation of spruce and barley PPCs that resulted in the separation of photosystem I (PSI) and photosystem II (PSII) supercomplexes (SCs), PSI and PSII core dimers, PSII core monomers, trimeric and monomeric light-harvesting complexes of PSII, and bands with free pigments. Studying the effect of elevated temperature on PPCs using CN-PAGE revealed different thermal stability of PPCs in spruce and barley tBMs. Pronounced PPCs changes were observed at temperatures at or above 40°C. We observed partial disappearance of PSII SCs bands at 44°C in barley and at 52°C in spruce. In addition, spruce PSI SCs exhibited slightly higher thermal stability than did barley PSI SCs. The increased thermal stability of spruce tBMS in comparison to that of barley tBM was also confirmed by the circular dichroism spectra of isolated tBMs at different temperatures (Karlický et al. 2015).
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The thermostability of photosystem II photochemistry is related to maintenance of thylakoid membranes organization
Karlický, Václav ; Kurasová, I. ; Špunda, Vladimír
For higher plant photosynthetic reactions, responses to the temperature changes are important, particularly if we consider global warming and the increasing frequency of extreme temperature fluctuations. High temperature stress decreases photosynthetic assimilation through the inactivation of photosystem II (PSII), the most heat-sensitive component of the oxygen-evolving complex. We have recently found higher thermostability of spruce PSII photochemistry compared to such control plants as Arabidopsis species and barley. In this work, we have therefore attempted to describe the causes of this effect on the level of the organization of pigment–protein complexes (PPCs) in spruce thylakoid membranes using circular dichroism (CD) spectroscopy. We have confirmed higher maximum efficiency of PSII photochemistry (FV/FM) for spruce needles in comparison to barley leaves. Temperature-dependent CD spectra have also demonstrated higher (by about 6°C) PSII thermostability of chiral macro-organization of PPCs in spruce thylakoid membranes compared to those in barley. However, thermal disruption of PPCs did not reveal significant differences. Our results demonstrate that the stability of PSII macro-organization in different plant species correlates with the thermostability of PSII photochemistry in intact needles/leaves and so effective PSII photochemistry is related to the maintenance of PSII macro-organization under high temperature stress.
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Elevated temperature stimulates light-induced processes that contribute to protecting photosystem II against oxidative stress
Materová, Z. ; Štroch, Michal ; Holubová, I. ; Sestřenková, J. ; Oravec, Michal ; Večeřová, Kristýna ; Špunda, Vladimír
We focused on elucidating the impact of elevated temperature on rapid induction of zeaxanthin (Z)- dependent photoprotection in two different plant species. The dynamics of violaxanthin (V) de-epoxidation under different illumination regimes was studied together with chlorophyll a fluorescence transients in Picea abies seedlings and Arabidopsis thaliana leaves pre-acclimated to temperatures ranging from 20 to 40°C. Whereas for spruce seedlings the rapid phase of V de-epoxidation (induced by either 10 s illumination or 10 light pulses 1 s in duration at 1 min intervals) was gradually stimulated upon increasing temperatures, for A. thaliana leaves considerable acceleration of V de-epoxidation occurred only at 40°C. Moreover, only for spruce seedlings was a considerable amount of Z accumulated after 10 × 1 s illumination. Elevated temperatures stimulated rapid formation of Z-dependent non-radiative dissipation of excitation energy within photosystem II (NRD) induced by 1 s light pulses only for spruce seedlings. The possible role of a specific fatty acid composition in spruce thylakoid membrane lipids in facilitated V de-epoxidation and NRD induction at elevated temperatures is discussed.
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Influence of variable weather on incident solar radiation and its spectral composition in the Ostrava region, Czech Republic
Opálková, M. ; Robson, T. M. ; Navrátil, M. ; Špunda, Vladimír
Incident solar radiation is influenced by many factors, including distance from the equator, altitude, time of year, and season. Absorption of radiation and its scattering are connected with the properties of atmospheric compounds. Cloud cover and air pollution are connected with tropospheric properties. Using our data, the influence of weather changes on the dose of solar irradiance reaching the Earth’s surface and its spectral composition are described. Solar radiation components were measured continuously by a system of sensors situated in the Botanical Garden of the University of Ostrava, Czech Republic. Data for 2014 were chosen for analyses. Days were divided into categories of sunny days and cloudy days according to weather conditions and daily radiation patterns. Percent differences in received solar radiation between sunny and cloudy days were calculated for eight months (Jan, Feb, Mar, Jun, Jul, Aug, Sep, and Dec). Differences in received solar radiation between clean and polluted days were calculated for sunny and cloudy days in December 2014. Mean incident solar radiation during cloudy days was reduced by 61% from the value for sunny days (in summer months) and by 64% from the value for sunny days in winter months. The largest influence of clouds on received solar radiation was during September and the smallest was during June. There was a reduction in incident solar radiation caused by the atmospheric pollutant PM10 during winter months. This reduction amounted to 10% during sunny days and 21% during cloudy days for December 2014. Clouds significantly reduced incident solar radiation as did the air pollutant PM10, but there were probably other factors also contributing to the reduction in incident solar radiation.
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Response of epidermal blue-green fluorescence emission from Barley leaves to uv radiation stress
Karlický, Václav ; Nezval, J. ; Štroch, Michal ; Špunda, Vladimír
Blue-green fl uorescence (BGF) is emitted by plant tissue when excited by UV radiation. Th e emission spectrum of BGF varies with plant species and is aff ected by the physiological status of the plant. BGF has been attributed mainly to cell wall-bound ferulic acid, although a contribution from fl avonoids and other simple phenols has also been suggested. Th e BGF signal is of interest due to its potential application in the remote sensing of plant stress: such techniques use ratios of blue and green to chlorophyll red and far-red fl uorescence emission intensities to estimate plant stress. In this work we investigated the response of BGF to UV-radiation stress and characterized changes in the shape of BGF emission spectra. We found these changes to be more signifi cant during the acclimation to UV-B radiation in comparison with UV-A or high irradiance of PAR. Furthermore, the spectral changes in BGF emission were due to a decline of fl uorescence at a wavelength of 435 nm compared with bands around 455 nm and 520 nm. In view of this, we have tried to distinguish individual fl uorescent components using more detailed fl uorescence analysis and to explain the causes of these spectral changes.
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Preconditioning under high par of exposure to UV-A radiation both allow acclimation of the photosynthetic apparatus of barley transferred to UV-B radiation
Štroch, Michal ; Materová, Z. ; Vrábl, D. ; Šigut, Ladislav ; Špunda, Vladimír
The acclimation response of the barley photosynthetic apparatus was examined aft er transfer of plants grown under low and high PAR to common conditions both with the same PAR and acute dose of UV-A and/or UV-B radiation. The aim was to evaluate how PAR received during growth aff ects the induction of regulatory and protective mechanisms during UV exposure. Contrary to UV-B radiation, UV-A exposure of barley plants acclimated to low PAR had no negative impact on the function of photosynthetic apparatus. Th e UV-A spectral region we used (350–400 nm) can be eff ectively utilised in photosynthetic reactions, thus compensating low PAR. Th e presence of UV-A radiation during acclimation to simultaneous UVA and UVB treatment not only mitigated but completely eliminated any negative eff ect of UV-B radiation on the photosynthetic function. Th e eff ect of UV-A and UV-B exposure was similar in plants grown under high PAR – causing moderately enhanced photosystem II (PSII) photoinhibition. We proposed that the ability to accumulate a considerable amount of UVscreening compounds under high PAR itself contributes to the resistance of PSII to UV-B radiation.
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CzechCarbo - studium cyklu uhlíku v terestrických ekosystémech ČR
Ústav fyziky atmosféry AV ČR, Praha ; Ostravská univerzita, Ostrava ; Univerzita Karlova, Praha ; Ústav pro hospodářskou úpravu lesů, Brandýs nad Labem ; Ústav ekologie krajiny AV ČR ; IDS Information and Data Systems, Praha ; Ústav pro výzkum lesních ekosystémů, s.r.o. , Strašice ; Jihočeská univerzita České Budějovice ; ENKI o.p.s., Třeboň ; Mendelova zemědělská a lesnická univerzita, Brno ; Ústav systémové biologie a ekologie AV ČR, České Budějovice ; Ústav ekologie krajiny AV ČR, České Budějovice ; Maxa, Josef ; Líšková, Zuzana ; Cudlínová, Eva ; Lapka, Miroslav ; Zemek, František ; Matějka, Karel ; Cudlín, Pavel ; Macků, Jaromír ; Henžlík, Vladimír ; Cienciala, Emil ; Černý, Martin ; Apltauer, Jan ; Janouš, Dalibor ; Šantrůčková, Hana ; Albrechtová, Jana ; Formánek, Pavel ; Špunda, Vladimír ; Čížková, Hana ; Soukupová, J. ; Urban, Otmar ; Huth, Radan ; Dubrovský, Martin ; Pokorný, Radek ; Marek, Michal V.
Projekt CzechCarbo představuje integrační projekt řešící problematiku studia cyklu uhlíku v terestrických ekosystémech ČR s využitím metodických přístupů umožňujících pochopit, predikovat a oceňovat bilanci uhlíku v ČR . Projekt je rozdělen do 8 pracovních segmentů. 1. Scénáře vývoje klimatu na území ČR s ohledem na globální změnu klimatu. 2. Studium mechanismů fyziologických procesů kontrolujících příjem a metabolismus uhlíku (účinkové procesové studie). 3. Rozvoj observační sítě "fluxes towers" umožňujících sledovat toky CO2 v základních typech ekosystémů ČR (lesy, louky, mokřady, agro-ekosystémy). 4. Zdokonalení regionálního území (území ČR) systému pro stanovení uhlíkové bilance terestrických (především lesních) ekosystémů, který lze použít při verifikaci a naplňování závěrů Kjótského protokolu. 5. Vypracování metodologie, která by byla schopna předpovídat budoucí vývoj a chování terestrických uhlíkových "sinků" v měřítku ČR. 6. Management lesních, lučních, mokřadních, vodních ekosystémů a agroekosystémů, snižující důsledky GHG (skleníkových plynů) a zvyšující příjem a ukládání C v krajině. 7. Změny koloběhu uhlíku v kontextu změny využití krajiny ČR (resp. globálních společenských a přírodních změn). 8. Sociální a ekonomické důsledky globální změny klimatu s ohledem na "land-use changes" a strategické chování společnosti. Příoha: Vázání uhlíku lesními ekosystémy a jeho místo v systému celospolečenských funkcí lesů. Ve zprávě jsou popsány výsledky, kterých bylo dosaženo v projektu v jednotlivých segmentech.
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