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Photosynthesis Research

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https://www.readbyqxmd.com/read/28547584/characterization-of-a-newly-isolated-freshwater-eustigmatophyte-alga-capable-of-utilizing-far-red-light-as-its-sole-light-source
#1
Benjamin M Wolf, Dariusz M Niedzwiedzki, Nikki Cecil M Magdaong, Robyn Roth, Ursula Goodenough, Robert E Blankenship
Oxygenic phototrophs typically utilize visible light (400-700 nm) to drive photosynthesis. However, a large fraction of the energy in sunlight is contained in the far-red region, which encompasses light beyond 700 nm. In nature, certain niche environments contain high levels of this far-red light due to filtering by other phototrophs, and in these environments, organisms with photosynthetic antenna systems adapted to absorbing far-red light are able to thrive. We used selective far-red light conditions to isolate such organisms in environmental samples...
May 25, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28540588/proteomic-analysis-of-the-phycobiliprotein-antenna-of-the-cryptophyte-alga-guillardia-theta-cultured-under-different-light-intensities
#2
Thomas Kieselbach, Otilia Cheregi, Beverley R Green, Christiane Funk
Plants and algae have developed various light-harvesting mechanisms for optimal delivery of excitation energy to the photosystems. Cryptophyte algae have evolved a novel soluble light-harvesting antenna utilizing phycobilin pigments to complement the membrane-intrinsic Chl a/c-binding LHC antenna. This new antenna consists of the plastid-encoded β-subunit, a relic of the ancestral phycobilisome, and a novel nuclear-encoded α-subunit unique to cryptophytes. Together, these proteins form the active α1β·α2β-tetramer...
May 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28540587/removal-of-the-h-subunit-results-in-enhanced-exposure-of-the-semiquinone-sites-in-the-lm-dimer-from-rhodobacter-sphaeroides-to-oxidation-by-ferricyanide-and-by-o2
#3
Chang Sun
Bacterial reaction centers (RC) from Rhodobacter sphaeroides have been widely used to functionalize electrodes and to generate photocurrent. However, in most studies, direct electron transfer from the semiquinone to the electrode was not observed because the H subunit of the RC shields the semiquinone. It is demonstrated in the current work that removal of the H subunit effectively exposes the semiquinone sites in the LM dimer. This is demonstrated by measuring the second-order rate constant for the reaction between ferricyanide and the anionic semiquinone Q A(-) formed by an actinic flash...
May 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28540586/leaf-photosynthetic-rate-and-mesophyll-cell-anatomy-changes-during-ontogenesis-in-backcrossed-indica%C3%A2-%C3%A3-%C3%A2-japonica-rice-inbred-lines
#4
Wenxing He, Shunsuke Adachi, Rowan F Sage, Taiichiro Ookawa, Tadashi Hirasawa
The high-yielding indica rice variety, 'Takanari', has the high rate of leaf photosynthesis compared with the commercial japonica varieties. Among backcrossed inbred lines from a cross between 'Takanari' and a japonica variety, 'Koshihikari', two lines, BTK-a and BTK-b, showed approximately 20% higher photosynthetic rate than that of 'Takanari' for a flag leaf at full heading. This is a highest recorded rate of rice leaf photosynthesis. Here, the timing and cause of the increased leaf photosynthesis in the BTK lines were investigated by examining the photosynthesis and related parameters, as well as mesophyll cell anatomy during ontogenesis...
May 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28536785/significance-of-accumulation-of-the-alarmone-p-ppgpp-in-chloroplasts-for-controlling-photosynthesis-and-metabolite-balance-during-nitrogen-starvation-in-arabidopsis
#5
Rina Honoki, Sumire Ono, Akira Oikawa, Kazuki Saito, Shinji Masuda
The regulatory nucleotides, guanosine 5'-triphosphate 3'-diphosphate (pppGpp) and guanosine 5'-diphosphate 3'-diphosphate (ppGpp), were originally identified in Escherichia coli, and control a large set of gene expression and enzyme activities. The (p)ppGpp-dependent control of cell activities is referred to as the stringent response. A growing number of (p)ppGpp synthase/hydrolase homologs have been identified in plants, which are localized in plastids in Arabidopsis thaliana. We recently reported that the Arabidopsis mutant overproducing ppGpp in plastids showed dwarf chloroplasts, and transcript levels in the mutant plastids were significantly suppressed...
May 23, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28536784/paul-henry-latimer-1925-2011-discoverer-of-selective-scattering-in-photosynthetic-systems
#6
Margaret Gwyn Latimer, Thomas T Bannister, Govindjee
We provide here a brief tribute to Paul Henry Latimer (November 25, 1925 to October 1, 2011), a dedicated biological physicist, discoverer of selective scattering in biological systems, a wonderful teacher, husband, and father. We provide here a glimpse of his personal and professional life, including reminiscences from F. Dudley Bryant, Dan A. Cross, Bobby E. Pyle, Bryan L. Seiber, and Bruce A. Seiber.
May 23, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28528494/carotenoid-to-bacteriochlorophyll-energy-transfer-in-the-rc-lh1-pufx-complex-from-rhodobacter-sphaeroides-containing-the-extended-conjugation-keto-carotenoid-diketospirilloxanthin
#7
Václav Šlouf, Gürkan Keşan, Radek Litvín, David J K Swainsbury, Elizabeth C Martin, C Neil Hunter, Tomáš Polívka
RC-LH1-PufX complexes from a genetically modified strain of Rhodobacter sphaeroides that accumulates carotenoids with very long conjugation were studied by ultrafast transient absorption spectroscopy. The complexes predominantly bind the carotenoid diketospirilloxanthin, constituting about 75% of the total carotenoids, which has 13 conjugated C=C bonds, and the conjugation is further extended to two terminal keto groups. Excitation of diketospirilloxanthin in the RC-LH1-PufX complex demonstrates fully functional energy transfer from diketospirilloxanthin to BChl a in the LH1 antenna...
May 20, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28523607/carotenoid-to-bacteriochlorophyll-energy-transfer-through-vibronic-coupling-in-lh2-from-phaeosprillum-molischianum
#8
Erling Thyrhaug, Craig N Lincoln, Federico Branchi, Giulio Cerullo, Václav Perlík, František Šanda, Heiko Lokstein, Jürgen Hauer
The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structure-function relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theory and ultrafast spectroscopy; nevertheless, certain aspects of the convoluted relaxation network of LH2 lack a satisfactory explanation by conventional theories. For example, the initial carotenoid-to-bacteriochlorophyll energy transfer step necessary on visible light excitation was long considered to follow the Förster mechanism, even though transfer times as short as 40 femtoseconds (fs) have been observed...
May 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28523606/frederick-yi-tung-cho-1939-2011-his-phd-days-in-biophysics-the-photosynthesis-lab-and-his-patents-in-engineering-physics
#9
Govindjee, John C Munday, George C Papageorgiou
We present here a Tribute to Frederick Yi-Tung Cho (1939-2011), an innovative and ingenious biophysicist and an entrepreneur. He was one of the 4 earliest PhD students [see: Cederstrand (1965)-Carl Nelson Cederstrand; coadvisor: Eugene Rabinowitch; Papageorgiou (1968)-George C. Papageorgiou (coauthor of this paper); and Munday (1968)-John C. Munday Jr. (also a coauthor of this paper)] of one of us (Govindjee) in Biophysics at the University of Illinois at Urbana-Champaign (UIUC) during the late 1960s (1963-1968)...
May 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28523605/erratum-to-connectivity-between-electron-transport-complexes-and-modulation-of-photosystem-ii-activity-in-chloroplasts
#10
Alexander N Tikhonov, Alexey V Vershubskii
No abstract text is available yet for this article.
May 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28497193/evaluation-of-new-cu-ii-complexes-as-a-novel-class-of-inhibitors-against-plant-carbonic-anhydrase-glutathione-reductase-and-photosynthetic-activity-in-photosystem-ii
#11
Margarita V Rodionova, Sergei K Zharmukhamedov, Mehmet Sayım Karacan, Kubra Begum Venedik, Alexandr V Shitov, Turgay Tunç, Serhat Mamaş, Vladimir D Kreslavski, Nurcan Karacan, Vyacheslav V Klimov, Suleyman I Allakhverdiev
Increasing inefficiency of production of important agricultural plants raises one of the biggest problems in the modern world. Herbicide application is still the best method of weed management. Traditional herbicides blocking only one of the plant metabolic pathways is ineffective due to the rapid growth of herbicide-resistant weeds. The synthesis of novel compounds effectively suppressing several metabolic processes, and therefore achieving the synergism effect would serve as the alternative approach to weed problem...
May 11, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28497192/redox-changes-of-ferredoxin-p700-and-plastocyanin-measured-simultaneously-in-intact-leaves
#12
Ulrich Schreiber
Properties and performance of the recently introduced Dual/KLAS-NIR spectrophotometer for simultaneous measurements of ferredoxin (Fd), P700, and plastocyanin (PC) redox changes, together with whole leaf chlorophyll a (Chl) fluorescence (emission >760, 540 nm excitation) are outlined. Spectral information on in vivo Fd, P700, and PC in the near-infrared region (NIR, 780-1000 nm) is presented, on which the new approach is based. Examples of application focus on dark-light and light-dark transitions, where maximal redox changes of Fd occur...
May 11, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28493058/c-terminal-cleavage-of-the-lh1-%C3%AE-polypeptide-in-the-sr-2-cultured-thermochromatium-tepidum
#13
Yukihiro Kimura, Tomoaki Kawakami, Teruhisa Arikawa, Yong Li, Long-Jiang Yu, Takashi Ohno, Michael T Madigan, Zheng-Yu Wang-Otomo
The light-harvesting 1 reaction center (LH1-RC) complex in the thermophilic purple sulfur bacterium Thermochromatium (Tch.) tepidum binds Ca ions as cofactors, and Ca-binding is largely involved in its characteristic Q y absorption at 915 nm and enhanced thermostability. Ca(2+) can be biosynthetically replaced by Sr(2+) in growing cultures of Tch. tepidum. However, the resulting Sr(2+)-substituted LH1-RC complexes in such cells do not display the absorption maximum and thermostability of those from Ca(2+)-grown cells, signaling that inherent structural differences exist in the LH1 complexes between the Ca(2+)- and Sr(2+)-cultured cells...
May 10, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28493057/absorptance-determinations-on-multicellular-tissues
#14
Román Manuel Vásquez-Elizondo, Lyz Legaria-Moreno, Miguel Ángel Pérez-Castro, Wiebke E Krämer, Tim Scheufen, Roberto Iglesias-Prieto, Susana Enríquez
The analysis of the variation of the capacity and efficiency of photosynthetic tissues to collect solar energy is fundamental to understand the differences among species in their ability to transform this energy into organic molecules. This analysis may also help to understand natural changes in species distribution and/or abundance, and differences in species ability to colonize contrasting light environments or respond to environmental changes. Unfortunately, the challenge that optical determinations on highly dispersive samples represent has strongly limited the progression of this analysis on multicellular tissues, limiting our knowledge of the role that optical properties of photosynthetic tissues may play in the optimization of photosynthesis and growth of benthonic primary producers...
May 10, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28432538/superoxide-generated-in-the-chloroplast-stroma-causes-photoinhibition-of-photosystem-i-in-the-shade-establishing-tree-species-psychotria-henryi
#15
Wei Huang, Ying-Jie Yang, Jiao-Lin Zhang, Hong Hu, Shi-Bao Zhang
Our previous studies indicated that high light induced significant photoinhibition of photosystem I (PSI) in the shade-establishing tree species Psychotria henryi. However, the underlying mechanism has not been fully clarified. In the present study, in order to investigate the mechanism of PSI photoinhibition in P. henryi, we treated detached leaves with constant high light in the presence of methyl viologen (MV) or a soluble α-tocopherol analog, 2,2,5,7,8-pentamethyl-6-chromanol (PMC). We found that MV significantly depressed photochemical quantum yields in PSI and PSII when compared to PMC...
April 21, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28425026/photosynthetic-responses-to-temperature-across-leaf-canopy-ecosystem-scales-a-15-year-study-in-a-californian-oak-grass-savanna
#16
Siyan Ma, Jessica L Osuna, Joseph Verfaillie, Dennis D Baldocchi
Ecosystem CO2 fluxes measured with eddy-covariance techniques provide a new opportunity to retest functional responses of photosynthesis to abiotic factors at the ecosystem level, but examining the effects of one factor (e.g., temperature) on photosynthesis remains a challenge as other factors may confound under circumstances of natural experiments. In this study, we developed a data mining framework to analyze a set of ecosystem CO2 fluxes measured from three eddy-covariance towers, plus a suite of abiotic variables (e...
April 19, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28425025/light-induced-formation-of-dimeric-lhcii
#17
Ewa Janik, Joanna Bednarska, Karol Sowinski, Rafal Luchowski, Monika Zubik, Wojciech Grudzinski, Wieslaw I Gruszecki
It emerges from numerous experiments that LHCII, the major photosynthetic antenna complex of plants, can appear not only in the trimeric or monomeric states but also as a dimer. We address the problem whether the dimeric form of the complex is just a simple intermediate element of the trimer-monomer transformation or if it can also be a physiologically relevant molecular organization form? Dimers of LHCII were analyzed with application of native electrophoresis, time-resolved fluorescence spectroscopy, and fluorescence correlation spectroscopy...
April 19, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405863/high-light-acclimation-of-chromera-velia-points-to-photoprotective-npq
#18
Erica Belgio, Eliška Trsková, Eva Kotabová, Daniela Ewe, Ondřej Prášil, Radek Kaňa
It has previously been shown that the long-term treatment of Arabidopsis thaliana with the chloroplast inhibitor lincomycin leads to photosynthetic membranes enriched in antennas, strongly reduced in photosystem II reaction centers (PSII) and with enhanced nonphotochemical quenching (NPQ) (Belgio et al. Biophys J 102:2761-2771, 2012). Here, a similar physiological response was found in the microalga Chromera velia grown under high light (HL). In comparison to cells acclimated to low light, HL cells displayed a severe re-organization of the photosynthetic membrane characterized by (1) a reduction of PSII but similar antenna content; (2) partial uncoupling of antennas from PSII; (3) enhanced NPQ...
April 12, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405862/isolation-and-characterization-of-psi-lhci-super-complex-and-their-sub-complexes-from-a-red-alga-cyanidioschyzon-merolae
#19
Lirong Tian, Zheyi Liu, Fangjun Wang, Liangliang Shen, Jinghua Chen, Lijing Chang, Songhao Zhao, Guangye Han, Wenda Wang, Tingyun Kuang, Xiaochun Qin, Jian-Ren Shen
Photosystem I (PSI)-light-harvesting complex I (LHCI) super-complex and its sub-complexes PSI core and LHCI, were purified from a unicellular red alga Cyanidioschyzon merolae and characterized. PSI-LHCI of C. merolae existed as a monomer with a molecular mass of 580 kDa. Mass spectrometry analysis identified 11 subunits (PsaA, B, C, D, E, F, I, J, K, L, O) in the core complex and three LHCI subunits, CMQ142C, CMN234C, and CMN235C in LHCI, indicating that at least three Lhcr subunits associate with the red algal PSI core...
April 12, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28405861/pk-a-of-ubiquinone-menaquinone-phylloquinone-plastoquinone-and-rhodoquinone-in-aqueous-solution
#20
Ryo Hasegawa, Keisuke Saito, Tomohiro Takaoka, Hiroshi Ishikita
Quinones can accept two electrons and two protons, and are involved in electron transfer and proton transfer reactions in photosynthetic reaction centers. To date, the pK a of these quinones in aqueous solution have not been reported. We calculated the pK a of the initial protonation (Q(·-) to QH(·)) and the second protonation (QH(-) to QH2) of 1,4-quinones using a quantum chemical approach. The calculated energy differences of the protonation reactions Q(·-) to QH(·) and QH(-) to QH2 in the aqueous phase for nine 1,4-quinones were highly correlated with the experimentally measured pK a(Q(·-)/QH(·)) and pK a(QH(-)/QH2), respectively...
April 12, 2017: Photosynthesis Research
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