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1142. Fluorescence emission, energy transfer and structure of pliycobílisomes from NostocflagelUforme Born. et Flah. during dissociation
- Creator:
- Lu, Rong-zhao and Liu, Bin
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Changes in fluorescence emission spectra (293 and 77 K) of phycobilisomes from Nostoc flagelUforme during dissociation in phosphate buffer of various molarity were studied. There were three bands in 77 K fluorescence emission spectra of partly dissociated phycobilisomes: F648, F666 and F686, characteristic of C-phycocyanin (C-PC), allophycocyanin (APC) and allophycocyanin-B (APC-B), respectively. In severely dissociated phycobilisomes, the F666 band was veiy weak, which indicated that linkage between C-PC and APC was severely dissociated, most of the energy trapped by C-PC could not be transferred to APC, but some of it could be transferred directly to APC-B. The phycobiliproteins in these phycobilisomes constitute an energy transfer chain: PEC^C;PC-»APC-»AP^-B. A new model of phycobilisome structure is suggested, in which some C-PC contact directly with APC and others contact with APC-B.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1143. Fluorescence excitation spectra of drought resistant and sensitive genotypes of triticale and maize
- Creator:
- Grzesiak, M. T., Rzepka, A., Hura, T., Grzesiak, S., Hura, K., Filek, W., and Skoczowski, A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Triticale and Zea
- Language:
- Multiple languages
- Description:
- An influence of soil drought (7 or 14 d) and 7 d recovery on changes of leaf fluorescence excitation spectra at wavelengths of 450, 520, 690, and 740 nm (F450, F520, F690, F740) for drought resistant and sensitive genotypes of triticale and maize was compared. In non-stressed plants the differences between maize and triticale were observed for F450 and F520, but not for F690 and F740. Drought caused the increase in F450, F520, and F690 and this increase was more distinct for drought sensitive genotypes. After re-hydration, chlorophyll fluorescence mostly recovered to values of control plants. Drought caused significant increase in F690/F740 but not in F450/F690 and F450/F520. For triticale, highest increase in F690/F740 was observed in the 4th and 7th leaves of resistant genotype and contrarily in maize for the sensitive one. After recovery, the F450/F520, F450/F690, and F690/F740 ratios mostly returned to values of control plants. and M. T. Grzesiak ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1144. Fluorescence hole-burning and site-selective studies of LHCII
- Creator:
- Gibasiewicz, K., Rutkowski, M., and van Grondelle, R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, fluorescence, light-harvesting complex II, line-narrowing, and zero-phonon line
- Language:
- Multiple languages
- Description:
- We report the observation of two types of changes in fluorescence spectra of LHCII at 4.2 K following intense illumination of the sample with a spectrally narrow laser beam at wavelengths between 678 and 686 nm. Nonspecific changes (burning-wavelength independent) are characterized by two relatively broad bands: a positive one at - 678.7 nm and a negative one at - 680.8 nm. These changes reveal a -1.3-nm blue shift of the distribution of final emitters in LHCII, from 680.3 nm to - 679.0 nm independent of the excitation wavelength. Specific fluorescence changes (burning-wavelength dependent) are characterized by a sharp hole exactly at the burning wavelength, and positive changes directly to the shorter-and longer-wavelength side of the narrow hole. The negative changes are interpreted as zero-phonon holes, while the positive features are assigned to non-photochemical products. In the low-burning intensity experiment, in addition to the zero-phonon holes, we observed also the holes to the longer wavelength of the zero-phonon hole, which were assigned to a sum of phonon and pseudo-phonon side bands. The shapes of these extra holes are identical to the shapes of the holes revealed in the fluorescence line narrowing experiment. On the basis of the low-burning intensity experiment we estimated the upper limit of the electron-phonon coupling strength for LHCII, characterized by a Huang-Rhys factor of 1.5. and K. Gibasiewicz, M. Rutkowski, R. van Grondelle.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1145. Fluorescence imaging of light acclimation of brazilian atlantic forest tree species
- Creator:
- Dos Anjos, L., Oliva, M. A., and Kuki, K. N.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, chlorophyll fluorescence, light stress, photochemical efficiency, thermal dissipation, xanthophyll cycle, 2, and 58
- Language:
- Multiple languages
- Description:
- In the pursuit of knowledge on the biological behavior of Brazilian Atlantic Forest tree species, this study evaluated the susceptibility of the light-demanding species, Schinus terebinthifolia Raddi., Pseudobombax grandiflorum (Cav.) A. Robyns and Joannesia princeps Vell., and of the shade-tolerant species, Hymenaea courbaril L. var. stilbocarpa and Lecythis pisonis Camb, to photoinhibition and acclimation capacity. These species were first cultivated under two irradiance conditions, I20 (20% direct sunlight radiation) and I100 (all-sky or direct sunlight) and then transferred from I20 to I100. The effects of the sudden increase in light radiation intensity on photosynthetic activity were then evaluated through chlorophyll (Chl) fluorescence imaging, HPLC xanthophylls analysis, and cell membrane lipid peroxidation measurements. Light-demanding species were found to present a higher photochemical efficiency and higher acclimation capacity under high light irradiance than shade-tolerant species. The higher photoinhibition tolerance observed in light-demanding species was associated to their higher capacity for photochemical dissipation and dissipation of excess excitation energy via the xanthophyll cycle, leading to a lower ROS generation. The obtained results suggested that a knowledge of acclimation capacity, by means of Chl fluorescence imaging yields, is a useful indicator of species successional grouping., L. Dos Anjos, M. A. Oliva, and K. N. Kuki., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1146. Fluorescence induction of photosynthetic bacteria
- Creator:
- Sipka, G., Kis, M., Smart, J. L., and Maróti, P.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- přenos elektronů, electron transfer, bacterial photosynthesis, fluorescence transients, intact cells, 2, and 581
- Language:
- Multiple languages
- Description:
- The kinetics of bacteriochlorophyll fluorescence in intact cells of the purple nonsulfur bacterium Rhodobacter sphaeroides were measured under continuous and pulsed actinic laser diode (808 nm wavelength and maximum 2 W light power) illumination on the micro- and millisecond timescale. The fluorescence induction curve was interpreted in terms of a combination of photochemical and triplet fluorescence quenchers and was demonstrated to be a reflection of redox changes and electron carrier dynamics. By adjustment of the conditions of single and multiple turnovers of the reaction center, we obtained 11 ms-1 and 120 μs-1 for the rate constants of cytochrome c23+ detachment and cyclic electron flow, respectively. The effects of cytochrome c2 deletion and chemical treatments of the bacteria and the advantages of the fluorescence induction study on the operation of the electron transport chain in vivo were discussed., G. Sipka, M. Kis, J. L. Smart, P. Maróti., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1147. Fluorescence lifetime imaging (FLI) in real-time - a new technique in photosynthesis research
- Creator:
- Holub, O., Seufferheld, M. J., Gohlke, C., Govindjee, and Clegg, R. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Arabidopsis, Chlamydomonas, FLIM, frequency domain, homodyne, microscopy, modulation, phase, photosystems 1 and 2, stress, time domain, and Zea
- Language:
- Multiple languages
- Description:
- We describe an instrument that allows the rapid measurement of fluorescence lifetime-resolved images of leaves as well as sub-cellular structures of intact plants or single cells of algae. Lifetime and intensity fluorescence images can be acquired and displayed in real time (up to 55 lifetime-resolved images per s). Our imaging technique therefore allows rapid measurements that are necessary to determine the fluorescence lifetimes at the maximum (P level) fluorescence following initial illumination during the chlorophyll (Chl) a fluorescence transient (induction) in photosynthetic organisms. We demonstrate the application of this new instrument and methodology to measurements of: (1) Arabidopsis thaliana leaves showing the effect of dehydration on the fluorescence lifetime images; (2) Zea mays leaves showing differences in the fluorescence lifetimes due to differences in the bundle sheath cells (having a higher amount of low yield photosystem 1) and the mesophyll cells (having a higher amount of high yield photosystem 2); and (3) single cells of wild type Chlamydomonas reinhardtii and its non-photochemical quenching mutant NPQ2 (where the conversion of zeaxanthin to violaxanthin is blocked), with NPQ2 showing lowered lifetime of Chl a fluorescence. In addition to the lifetime differences referred to in (1) and (2), structural dependent heterogeneities in the fluorescence lifetimes were generally observed when imaging mesophyll cells in leaves. and O. Holub ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1148. Foliar anthocyanins in Pelargonium × hortorum are unable to alleviate light stress under photoinhibitory conditions
- Creator:
- Liakopoulos, G. and Spanorigas, I.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, anthocyanins, chlorophyll fluorescence, photoprotection, photosynthesis, photosystem II, 2, and 58
- Language:
- Multiple languages
- Description:
- Photosynthetic organs are often characterized by anthocyanins being accumulated either in the epidermal or in the mesophyll cells making these tissues to turn reddish-brown in colour. It has been hypothesized that these pigments protect underlying chloroplasts from light-stress because they absorb photons of the photosynthetically active waveband. However, the photoprotective role of anthocyanins has not been undoubtedly shown on a broad range of species. In this study, green and anthocyanic areas of leaves of Pelargonium × hortorum, the latter possessing variable levels of anthocyanins, were compared using pigment analysis and pulse amplitude modulated in vivo chlorophyll (Chl) fluorescence. Quenching analysis of the induction and dark relaxation curves of slow Chl fluorescence kinetics showed that at photoinhibitory conditions [by applying above-saturation light intensity of 1,600 μmol(quantum) m-2 s-1 white light at low (4°C) temperature], anthocyanic areas were at least equally sensitive to photoinhibition as green leaf areas. In fact, the level of photoinhibition tended to be proportional to the level of anthocyanin accumulation suggesting that this characteristic was indicative of the photoinhibitory risk. The results of the present study clearly show that anthocyanins in leaf areas of Pelargonium do not afford a photoprotective advantage., G. Liakopoulos, I. Spanorigas., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1149. Foliar application of 24-epibrassinolide alleviates high-temperature-induced inhibition of photosynthesis in seedlings of two melon cultivars
- Creator:
- Zhang, Y. P., Zhu, X. H., Ding, H. D., Yang, S. J., and Chen, Y. Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, brassinosteroids, chlorophyll content, chlorophyll fluorescence, gas exchange, plant growth, 2, and 581
- Language:
- Multiple languages
- Description:
- Brassinosteroids (BRs), an important class of plant steroidal hormones, play a significant role in the amelioration of various biotic and abiotic stresses. 24-epibrassinolide (EBR), an active brassinosteroid, was applied exogenously in different concentrations to characterize a role of BRs in tolerance of melon (Cucumis melo L.) to high temperature (HT) stress and to investigate photosynthetic performance of HT-stressed, Honglvzaocui (HT-tolerant) and Baiyuxiang (HTsensitive), melon variety. Under HT, Honglvzaocui showed higher biomass accumulation and a lower index of heat injury compared with the Baiyuxiang. The exogenous application of 1.0 mg L-1 EBR, the most effective concentration, alleviated dramatically the growth suppression caused by HT in both ecotypes. Similarly, EBR pretreatment of HTstressed plants attenuated the decrease in relative chlorophyll content, net photosynthetic rate, stomatal conductance, stomatal limitation, and water-use efficiency (WUE), as well as the maximal quantum yield of PSII photochemistry (Fv/Fm), the efficiency of excitation capture of open PSII center, the effective quantum yield of PSII photochemistry (ΦPSII), photochemical quenching coefficient, and the photon activity distribution coefficients of PSI (α). EBR pretreatment further inhibited the increase in intracellular CO2 concentration, leaf transpiration rate, minimal fluorescence of dark-adapted state, nonphotochemical quenching, thermal dissipation, and photon activity distribution coefficients of PSII. Results obtained here demonstrated that EBR could alleviate the detrimental effects of HT on the plant growth by improving photosynthesis in leaves, mainly reflected as up-regulation of photosynthetic pigment contents and photochemical activity associated with PSI. and Y. P. Zhang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1150. Foliar exposure of grapevine (Vitis vinifera L.) to TiO2 nanoparticles under field conditions: Photosynthetic response and flavonol profile
- Creator:
- Teszlák, P., Kocsis, M., Scarpellini, A., Jakab, G., and Kőrösi, L.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, oxid titaničitý, photosynthesis, titanium dioxide, chlorophyll fluorescence, flavonols, grapevine, macroelement, nanotoxicity, 2, and 581
- Language:
- Multiple languages
- Description:
- In the past decade, utilization of nanostructured materials has increased intensively in a wide range of applications. Titanium dioxide nanoparticles (TiO2 NPs), for instance, can be applied for the inactivation of various pathogens through photo-induced generation of reactive oxygen species. Although TiO2 NPs with high antimicrobial activity are of great importance, in practice, their phytotoxic effects have not yet been fully clarified. In this study, we investigated the potential phytotoxicity of TiO2 NPs on grapevine (Vitis vinifera L.) under field conditions. After foliar exposure, two particularly stress-sensitive parameters, photosynthetic function and the flavonol profile, were examined. Micro- and macroelement composition of the leaves was also studied by ICP-AES measurements. We found that TiO2 NPs significantly decreased the net CO2 assimilation and increased stomatal conductance, indicating metabolic (nonstomatal) inhibition of the photosynthesis. The lower electron transport rate and lower nonphotochemical quenching in treated leaves are indicative of diminished photoprotective processes., P. Teszlák, M. Kocsis, A. Scarpellini, G. Jakab, L. Kőrösi., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public