Number of results to display per page
Search Results
2872. Insights into nanoparticle-induced changes in plant photosynthesis
- Creator:
- Ghorbanpour, M., Movahedi, A., Hatami, M., Kariman, K., Bovand, F., and Shahid, M.A.
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, chloroplast, nanoparticles, and photosynthesis
- Language:
- Multiple languages
- Description:
- Photosynthesis can be affected by nanoparticles (NPs) both negatively (e.g., through decreasing the chlorophyll content and electron transport rate, damages to chloroplast components, etc.) or positively (e.g., via enhancing chlorophyll content, the activity of Rubisco enzyme, the performance of PSII, and CO2 harvesting, as well as broadening the chloroplast photoabsorption spectrum). Enhanced photosynthetic efficiency could be a possible impact of NPs on photosynthetic organisms of major economic and ecological significance (e.g., crops and algae), which warrants an in-depth understanding of NPs interactions with chloroplast and its structural components (e.g., thylakoid membranes), signaling molecules, and pathways involved in photosynthesis. In this review, we comprehensively explore the potential effects of NPs on photosynthesis in different photosynthetic organisms (terrestrial plants, aquatic plants, and algae), and highlight research limitations and possible practical implications.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2873. Insignie, medaile, taláry Univerzity Karlovy /
- Creator:
- Herber, Otto,
- Type:
- text and monografie
- Subject:
- Vysoké školy, Univerzita Karlova, insignie, symboly, and české a československé vědecké instituce a společnosti, vysoké školy
- Language:
- Multiple languages
- Rights:
- unknown
2874. Integrity and activity of photosystem 2 complexes isolated from the thermophilic cyanobacterium Synechococcus elongatus using various detergents
- Creator:
- Šetlíková, E., Sofrová, D., Prášil, O., Budáč, P., Koblížek, M., and Šetlík, I.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fluorescence induction, low temperature fluorescence spectra, oxygen evolution, PQ pool, QA- reoxidation, QB pocket, and thermoluminescence
- Language:
- Multiple languages
- Description:
- The efficiency in selective extraction of photosystem (PS) 2 oxygen evolving complexes was compared among seven detergents. These were applied to thylakoid membranes of the thermophilic cyanobacterium Synechococcus elongatus. Used were five non-ionic detergents with one ionic and one zwitterionic for comparison. To compare the suitability and efficiency of the detergents the following properties of the extracts were examined: maximum rate of oxygen evolution with various electron acceptors, the relative variable fluorescence (FV/FM), the contamination of the extract with photosystem (PS) 1, and the status of the electron acceptor side of PS2 reaction centre. None of the detergents yielded a highly selective extraction of the PS2 complexes (negligible contamination with PS1) which would simultaneously display a high photochemical activity and high structural intactness. Heptylthioglucoside and dodecylmaltoside yielded the nearest approximation to the optimum result. Kinetic fluorometry was applied here for the first time to characterize the functional and structural properties of PS2 particles from cyanobacteria. and E. Šetlíková ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2875. Interaction of anions and cations in regulating energy distribution between the two photosystems
- Creator:
- Jajoo, Anjana and Bharti, Sudhakar
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence induction, MgCl2, NaCl, Na2HPO4, Na2PO4, Na2SO4, spinach, Spinacia oleracea, state change, and thylakoids
- Language:
- Multiple languages
- Description:
- Cations such as Mg2+ regulate spillover of absorbed excitation energy mainly in favour of photosystem (PS) 2. Effect of low concentration (<10 mM) of the monovalent cation Na+ on chlorophyll (Chl) a fluorescence was completely overridden by divalent cation Mg2+ (5 mM). Based on Chl a fluorescence yield and 77 K emission measurements, we revealed the role and effectiveness of anions (Cl-, SO42-, PO43-) in lowering the Mg2+-induced PS2 fluorescence. The higher the valency of the anion, the lesser was the expression of Mg2+ effect. Anions may thus overcome Mg2+ effects up to certain extent in a valency dependent manner, thereby diverting more energy to PS1 even in the presence of MgCl2. They may do so by reversing Mg2+-induced changes. and Anjana Jajoo, Sudhakar Bharti.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2876. Interaction of cytokinins and abscisic acid during regulation of stomatal opening in bean leaves
- Creator:
- Pospíšilová, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- benzyladenine, net photosynthetic rate, Phaseolus vulgaris, stomatal conductance, transpiration rate, and water stress
- Language:
- Multiple languages
- Description:
- Effects of benzyladenine (BA) and abscisic acid (ABA) applied separately or simultaneously on parameters of gas exchange of Phaseolus vulgaris L. leaves were studied. In the first two experimental sets) 100 μM ABA and 10 μM BA were applied to plants sufficiently supplied with water. Spraying of leaves with ABA decreased stomatal conductance (gs) and in consequence transpiration rate (E) and net photosynthetic rate (PN) already 1 h after application, but 24 h after application the effect almost disappeared. 10 μM BA slightly decreased gas exchange parameters, but in simultaneous application with ABA reversed the effect of ABA. Immersion of roots into the same solutions markedly decreased gas exchange parameters and 24 h after ABA application the stomata were completely closed. The effect of ABA was ameliorated by simultaneous BA application, particularly after 1-h treatment. In the third experimental set, plants were pre-treated by immersing roots into water, 1 μM BA, or 100 μM ABA for 24 h and then the halves of split root system were dipped into different combinations of 1 μM BA, 100 μM ABA, and water. In plants pre-treated with ABA all gas exchange parameters were small and they did not differ in plants treated with H2O+H2O, H2O+BA, or BA+BA. In plants pre-treated with BA or H2O, markedly lower values of PN were found when both halves of roots were immersed in ABA. Further, the effects of pre-treatment of plants with water, 1 μM BA, 100 μM ABA, or ABA+BA on the development of water stress induced by cessation of watering and on the recovery after rehydration were followed. ABA markedly decreased gas exchange parameters at the beginning of the experiment, but in its later phase the effect was compensated by delay in development of water stress. BA also delayed development of water stress and increased PN in water-stressed leaves. BA reversed the effect of ABA at mild water stress. Positive effects of BA and ABA pre-treatments were observed also after rehydration.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2877. Interaction of photosystem 2-LHC2 supercomplexes in adjacent layers of stacked chloroplast thylakoid membranes
- Creator:
- Bumba, L., Hušák, M., and Vácha, F.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- electron microscopy, membrane proteins, model, photosynthesis, photosystem 2, Pisum, and single particle image analysis
- Language:
- Multiple languages
- Description:
- Two types of photosystem 2-light-harvesting complex 2 (PS2-LHC2) supercomplexes with similar pigment and protein composition were isolated directly from thylakoid membranes by sucrose density gradient centrifugation. Electron microscopy and single particle image analysis revealed the first Type as single unpaired PS2-LHC2 supercomplexes, whereas the second Type was characterized as pairs of two PS2-LHC2 supercomplexes attached together by their stromal sides. Unstacking of thylakoid membranes resulted in a spontaneous disintegration of the paired supercomplexes into single unpaired particles. A model of the organisation of the pigment-protein complexes in grana region is proposed. and L. Bumba, M. Hušák, F. Vácha.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2878. Interaction of salicylic acid and ethylene and their effects on some physiological and biochemical parameters in canola plants (Brassica napus L.)
- Creator:
- Tirani, M. M., Nasibi, F., and Kalantari, Kh. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, lipid peroxidation, oxidative stress, phenolic compound, photosynthetic pigments, 2, and 581
- Language:
- Multiple languages
- Description:
- Environmental stresses, such as cold, heat, salinity, and drought, induce ethylene production and oxidative stress and cause damage in plants. On the other hand, studies have shown that salicylic acid (SA) induced resistance to environmental stresses in plants. In this research, the effects of ethylene on chlorophyll (Chl), carotenoid (Car), anthocyanin, flavonoids, ascorbic acid, dehydroascorbic acid, total ascorbate, lipid peroxidation, and ethylene production in leaves of canola pretreated with SA were studied. The plants were grown in pots until they have four leaves. Leaves were sprayed for two days with three different concentrations of SA (0, 0.5, and 1 mM). The plants were treated for three days with three concentrations of ethylene (0, 50, and 100 ppm). At the end of the ethylene treatments, all examined parameters were measured. The results showed that the ethylene treatments induced lipid peroxidation, while SA mitigated this effect. The ethylene treatment lowered significantly Chl and Car contents and anthocyanin accumulation, but SA alleviated these effects. SA induced an increase in ascorbic acid content in canola plants after the ethylene treatments. Therefore, we concluded that SA played an important role in the alleviation of damages caused by stress conditions. and M. M. Tirani, F. Nasibi, Kh. M. Kalantari.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2879. Interactions between nitrogen fertilization and ozone in watermelon cultivar Reina de Corazones in open-top chambers. Effects on chlorophyll a fluorescence, lipid peroxidation, and yield
- Creator:
- Calayud, A., Pomares, F., and Barreno, E.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Citrollus lanatus, photochemical and non-photochemical quenching, photoinhibition, photosystem 2, and quantum yield
- Language:
- Multiple languages
- Description:
- Watermelon (Citrillus lanatus) plants were grown for two consecutive years in open-top chambers with three different ozone concentrations (O3-free air, O3 ambient, and air with additional O3; CFA, NFA, and NFA+O3) and three nitrogen fertilizer concentrations [0, 14.0, and 29.6 g N per pot; N0, N1, and N2). There was an interaction between ozone and N fertilizer for the major parameters studied. O3 and N2 treatments led to a significant decrease in maximum efficiency of photosystem 2 (PS2) photochemistry (Fv/Fm), and induced a significant decrease in the actual quantum yield of PS2 (ΦPS2), due mainly to the increased closure of PS2 reaction centres (qP) and to an increase in the non-photochemical quenching (NPQ). On the other hand, these plants exhibited an increased susceptibility to photoinhibition, which could be associated with an increased fraction of reduced QA. An increase in lipid peroxidation indicated that damage was occurring at the membrane levels. High N concentration enhanced the detrimental effects of ozone on the fluorescence parameter induction and lipid peroxidation. All these negative alterations led to a decreased yield. and A. Calatayud, F. Pomares, E. Barreno.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2880. Interactions between photosynthetic pigments in organisms and in model systems
- Creator:
- Frąckowiak, D. and Smyk, B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, delayed luminescence, excitation energy migration, models, photoacoustic spectroscopy, photosystem 2 reaction centres, polarized radiation, and thermal deactivation
- Language:
- Multiple languages
- Description:
- The review summarizes results concerning photosynthetic systems with chlorophylls and carotenoids obtained by means of spectral methods such as polarized radiation, photoacoustic spectroscopy, delayed luminescence, thermal deactivation, and leading to construction of model systems. and D. Frąckowiak, B. Smyk.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public