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Michael St J Warne, Olivia King, Rachael A Smith
Triazine and urea herbicides are two groups of photosystem II inhibiting herbicides frequently detected in surface, ground and marine waters. Yet, there are few water quality guidelines for herbicides. Ecotoxicity thresholds (ETs) for ametryn, hexazinone and simazine (triazine herbicides) and diuron (a urea herbicide) were calculated using the Australian and New Zealand method for deriving guideline values to protect fresh and marine ecosystems. Four ETs were derived for each chemical and ecosystem that should theoretically protect 99, 95, 90 and 80% of species (i...
January 14, 2018: Environmental Science and Pollution Research International
Hiroki Makita, Gary Hastings
Time-resolved FTIR difference spectroscopy has been used to study photosystem I (PSI) particles with three different benzoquinones [plastoquinone-9 (PQ), 2,6-dimethyl-1,4-benzoquinone (DMBQ), 2,3,5,6-tetrachloro-1,4-benzoquinone (Cl4BQ)] incorporated into the A1 binding site. If PSI samples are cooled in the dark to 77 K, the incorporated benzoquinones are shown to be functional, allowing the production of time-resolved (P700+A1--P700A1) FTIR difference spectra. If samples are subjected to repetitive flash illumination at room temperature prior to cooling, however, the time-resolved FTIR difference spectra at 77 K display contributions typical of the P700 triplet state (3P700), indicating a loss of functionality of the incorporated benzoquinones, that occurs because of double protonation of the incorporated benzoquinones...
January 13, 2018: Photosynthesis Research
Xiaocui Ma, Chong Chen, Minmin Yang, Xinchun Dong, Wei Lv, Qingwei Meng
Chilling stress severely affects the growth, development and productivity of crops. Chloroplast, a photosynthesis site, is extremely sensitive to chilling stress. In this study, the functions of a gene encoding a cold-regulated protein (SlCOR413IM1) under chilling stress were investigated using sense and antisense transgenic tomatoes. Under chilling stress, SlCOR413IM1 expression was rapidly induced and the sense lines exhibited better growth state of seedlings and grown tomato plants. Overexpression of SlCOR413IM1 alleviated chilling-induced damage to the chloroplast membrane and structure, whereas suppression of SlCOR413IM1 aggravated the damage to chloroplast...
January 5, 2018: Plant Physiology and Biochemistry: PPB
Chao Tang, Chuanjun Yang, Hui Yu, Shen Tian, Xiaomei Huang, Weiyi Wang, Peng Cai
Photosynthesis of Microcystis aeruginosa under Electromagnetic Radiation (1.8 GHz, 40 V/m) was studied by using the proteomics. A total of 30 differentially expressed proteins, including 15 up-regulated and 15 down-regulated proteins, were obtained in this study. The differentially expressed proteins were significantly enriched in the photosynthesis pathway, in which the protein expression levels of photosystems II cytochrome b559 α subunit, cytochrome C550, PsbY, and F-type ATP synthase (a, b) decreased...
January 11, 2018: Scientific Reports
Nia Petrova, Svetla Todinova, Hajnalka Laczko-Dobos, Tomas Zakar, Sindhujaa Vajravel, Stefka Taneva, Zoltan Gombos, Sashka Krumova
Phycobilisomes (PBSs) are supramolecular pigment-protein complexes that serve as light-harvesting antennae in cyanobacteria. They are built up by phycobiliproteins assembled into allophycocyanin core cylinders (ensuring the physical interaction with the photosystems) and phycocyanin rods (protruding from the cores and having light-harvesting function), the whole PBSs structure being maintained by linker proteins. PBSs play major role in light-harvesting optimization in cyanobacteria; therefore, the characterization of their structural integrity in intact cells is of great importance...
January 10, 2018: Photosynthesis Research
Junping Chen, John J Burke, Zhanguo Xin
BACKGROUND: Photosynthetic systems are known to be sensitive to high temperature stress. To maintain a relatively "normal" level of photosynthetic activities, plants employ a variety of adaptive mechanisms in response to environmental temperature fluctuations. Previously, we reported that the chloroplast-targeted AtFtsH11 protease played an essential role for Arabidopsis plants to survive at high temperatures and to maintain normal photosynthetic efficiency at moderately elevated temperature...
January 10, 2018: BMC Plant Biology
Ivan V Shelaev, Mahir D Mamedov, Fedor E Gostev, Arseny V Aybush, Meng Li, Jonathan Nguyen, Barry D Bruce, Victor A Nadtochenko
Photosystem I (PSI) is a Type-I reaction center and the largest photosynthetic complex to be characterized. In cyanobacteria, PSI is organized as a trimer with a three-fold axis of symmetry. Recently, a tetrameric form of PSI has been identified in cyanobacteria. Plastids in plants and algae only contain monomeric PSI, suggesting that tetrameric PSI may be key in the transition from ancestral cyanobacterial trimeric PSI to plant/algal monomeric PSI. We have investigated the kinetics of e- transfer to the initial acceptor in PSI tetramer isolated from Chroococcidiopsis TS-821...
January 8, 2018: Photochemistry and Photobiology
Orestis Antonoglou, Julietta Moustaka, Ioannis Dimosthenis Adamakis, Ilektra Sperdouli, Anastasia A Pantazaki, Michael Moustakas, Catherine Dendrinou-Samara
Inorganic nanoparticles (NPs) have been proposed as alternative fertilizers to suppress plant disease and increase crop yield. However, phytotoxicity of NPs remains a key factor for their massive employment in agricultural applications. In order to investigate new effective, non phytotoxic and inexpensive fungicides, in the present study CuZn bimetallic nanoparticles (BNPs) have been synthesized as antifungals, while assessment of photosystem II (PSII) efficiency by chlorophyll fluorescence imaging analysis is utilized as an effective and non-invasive phytotoxicity evaluation method...
January 9, 2018: ACS Applied Materials & Interfaces
Lingling Zhu, Keith J Bloomfield, Charles H Hocart, John J G Egerton, Odhran S O'Sullivan, Aurore Penillard, Lasantha K Weerasinghe, Owen K Atkin
In many biomes, plants are subject to heat-waves, potentially causing irreversible damage to the photosynthetic apparatus. Field surveys have documented global, temperature-dependent patterns in photosynthetic heat tolerance (PHT ); however, it remains unclear if these patterns reflect acclimation in PHT or inherent differences among species adapted to contrasting habitats. To address these unknowns, we quantified seasonal variations in Tcrit (high temperature where minimal chlorophyll-a fluorescence rises rapidly, reflecting disruption to photosystem II) in 62 species native to six sites from five thermally-contrasting biomes across Australia...
January 5, 2018: Plant, Cell & Environment
Yongfeng Lou, Huayu Sun, Sining Wang, Hao Xu, Lichao Li, Hansheng Zhao, Zhimin Gao
Higher plants have an array of photoprotection mechanisms alleviating the harmful effects of light. Non-photochemical quenching (NPQ) is one of the photoprotective mechanisms, which dissipates the excess of light energy absorbed in the light-harvesting complexes (LHCs) into thermal energy. The PsbS (photosystem II subunit S), a member of the LHC family thought to be present exclusively in higher plants, is supposed to activate NPQ through interactions with antenna proteins. However, the roles of PsbS in bamboo remain unclear...
January 4, 2018: Physiologia Plantarum
Aina E Prinzenberg, Marcela Víquez-Zamora, Jeremy Harbinson, Pim Lindhout, Sjaak van Heusden
Physiology and genetics are tightly interrelated. Understanding the genetic basis of a physiological trait such as the quantum yield of the photosystem II, or photosynthetic responses to environmental changes will benefit the understanding of these processes. By means of chlorophyll fluorescence imaging "CF", the quantum yield of photosystem II can be determined rapidly, precisely and non-invasively. In this article, the genetic control and variation in the steady-state quantum yield of PSII "ΦPSII " is analysed for diploid potato plants...
January 4, 2018: Physiologia Plantarum
P Ventura, G Toullec, C Fricano, L Chapron, V Meunier, E Röttinger, P Furla, S Barnay-Verdier
In the context of global change, symbiotic cnidarians are largely affected by seawater temperature elevation leading to symbiosis breakdown. This process, also called bleaching, is triggered by the dysfunction of the symbiont photosystems causing an oxidative stress and cell death to both symbiont and host cells. In our study, we wanted to elucidate the intrinsic capacity of isolated animal cells to deal with thermal stress in the absence of symbiont. In that aim, we have characterized an animal primary cell culture form regenerating tentacles of the temperate sea anemone Anemonia viridis...
January 8, 2018: Marine Biotechnology
David A Marchiori, Paul H Oyala, Richard J Debus, Troy A Stich, R David Britt
The Mn4CaO5 oxygen-evolving complex (OEC) of photosystem II catalyzes the light-driven oxidation of two substrate waters to molecular oxygen. An ELDOR-detected NMR and computational study has indicated that ammonia, a substrate analogue, binds as a terminal ligand to the Mn4A ion trans to the O5 μ4 oxido bridge.[Perez Navarro M., et al., Proc. Natl. Acad. Sci. U.S.A. 2013, 110, 15561-15566] A subsequent electron spin echo envelope modulation (ESEEM) study confirmed this result and showed that ammonia hydrogen bonds to the carboxylate sidechain of D1-Asp61...
January 5, 2018: Journal of Physical Chemistry. B
Yi Xu, Jinyu Wang, Stacy A Bonos, William A Meyer, Bingru Huang
Heat stress is one of the major abiotic factors limiting the growth of cool-season grass species during summer season. The objectives of this study were to assess genetic variations in the transcript levels of selected genes in fine fescue cultivars differing in heat tolerance, and to identify single nucleotide polymorphism (SNP) markers associated with candidate genes related to heat tolerance. Plants of 26 cultivars of five fine fescue species (Festuca spp.) were subjected to heat stress (38/33 °C, day/night temperature) in controlled environmental growth chambers...
January 1, 2018: International Journal of Molecular Sciences
Rhys Wyber, Barry Osmond, Michael B Ashcroft, Zbynek Malenovský, Sharon A Robinson
Understanding the net photosynthesis of plant canopies requires quantifying photosynthesis in challenging environments, principally due to the variable light intensities and qualities generated by sunlight interactions with clouds and surrounding foliage. The dynamics of sunflecks and rates of change in light intensity at the beginning and end of sustained light (SL) events makes photosynthetic measurements difficult, especially when dealing with less accessible parts of plant foliage. High time resolved photosynthetic monitoring from pulse amplitude modulated (PAM) fluorometers has limited applicability due to the invasive nature of frequently applied saturating flashes...
December 28, 2017: Tree Physiology
Jooyeon Jeong, Kwangryul Baek, Jihyeon Yu, Henning Kirst, Nico Betterle, Woongghi Shin, Sangsu Bae, Anastasios Melis, EonSeon Jin
Nuclear-encoded light-harvesting chlorophyll- and carotenoid-binding proteins (LHCPs) are imported into the chloroplast and transported across the stroma to thylakoid membrane assembly sites by the chloroplast signal recognition particle (CpSRP) pathway. The LHCP translocation defect (LTD) protein is essential for the delivery of imported LHCPs to the CpSRP pathway in Arabidopsis. However, the function of the LTD protein in Chlamydomonas reinhardtii has not been investigated. Here, we generated a C. reinhardtii ltd (Crltd) knockout mutant by using CRISPR-Cas9, a new target-specific knockout technology...
December 30, 2017: Journal of Experimental Botany
Yuan Cao, Mingquan Jiang, Fuling Xu, Shuo Liu, Fanjuan Meng
Some ploidy plants demonstrate environmental stress tolerance. Tetraploid (4×) black locust (Robinia pseudoacacia L.) exhibits less chlorosis in response to high CO 2 than do the corresponding diploid (2×) plants of this species. We investigated the plant growth, anatomy, photosynthetic ability, chlorophyll (chl) fluorescence, and antioxidase activities in 2× and 4× black locusts cultivated under high CO 2 (0.5%). Elevated CO 2 (0.5%) induced a global decrease in the contents of total chl, chl a, and chl b in 2× leaves, while few changes were found in the chl content of 4× leaves...
December 2017: Ecology and Evolution
Robert C Jennings, Erica Belgio, Giuseppe Zucchelli
It is often suggested that Life may lay outside the normal laws of Physics and particularly of Thermodynamics, though this point of view is refuted by many. As the Living State may be thought of as an open system, often far from equilibrium, most attempts at placing Life under the umbrella of the laws of Physics have been based, particularly in recent years, on non-equilibrium Thermodynamics and particularly the Maximum Entropy Production Principle. In this view it is the dissipation of entropy (heat) which permits the ever increasing complexity of Living Systems in biological evolution and the maintenance of this complexity...
December 19, 2017: Biophysical Chemistry
Veronique Larosa, Andrea Meneghesso, Nicoletta La Rocca, Janina Steinbeck, Michael Hippler, Ildiko Szabo, Tomas Morosinotto
Photosynthetic organisms use sunlight as the primary source of energy to support their metabolism. In eukaryotes reactions responsible of the conversion of light into chemical energy occur in specific organelles, the chloroplasts. In this study we showed that mitochondria also have a seminal influence on cells' energy metabolism and on photosynthetic reactions. This is illustrated by the observation that the strong photosensitivity of Chlamydomonas reinhardtii cells depleted of the chloroplast protein PGRL1 was rescued by the introduction of a mitochondrial mutation affecting respiratory complex I...
December 28, 2017: Plant Physiology
Tim Jiang, Edward Saehong Oh, Diana Bonea, Rongmin Zhao
Arabidopsis plastidic HSP90C is an HSP90 family molecular chaperone that is required for chloroplast development and function. To understand the mechanism of action of HSP90C within the chloroplast, we conducted a yeast two-hybrid screening and revealed it interacts directly with the photosystem II extrinsic protein PsbO1, which performs a canonical function in the thylakoid lumen. To understand the biological significance of HSP90C-PsbO1 interaction, we investigated the role of HSP90C in modulating the stromal and thylakoid distribution of PsbO1GFP fusion protein...
2017: PloS One
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