Articles de revues : « "light harvesting stress related protein 1" »

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Girolomoni, Laura, Stefano Cazzaniga, Alberta Pinnola, Federico Perozeni, Matteo Ballottari et Roberto Bassi. « LHCSR3 is a nonphotochemical quencher of both photosystems inChlamydomonas reinhardtii ». Proceedings of the National Academy of Sciences 116, n^o 10 (19 février 2019) : 4212–17. http://dx.doi.org/10.1073/pnas.1809812116.

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Photosynthetic organisms prevent oxidative stress from light energy absorbed in excess through several photoprotective mechanisms. A major component is thermal dissipation of chlorophyll singlet excited states and is called nonphotochemical quenching (NPQ). NPQ is catalyzed in green algae by protein subunits called LHCSRs (Light Harvesting Complex Stress Related), homologous to the Light Harvesting Complexes (LHC), constituting the antenna system of both photosystem I (PSI) and PSII. We investigated the role of LHCSR1 and LHCSR3 in NPQ activation to verify whether these proteins are involved in thermal dissipation of PSI excitation energy, in addition to their well-known effect on PSII. To this aim, we measured the fluorescence emitted at 77 K by whole cells in a quenched or unquenched state, using green fluorescence protein as the internal standard. We show that NPQ activation by high light treatment inChlamydomonas reinhardtiileads to energy quenching in both PSI and PSII antenna systems. By analyzing quenching properties of mutants affected on the expression of LHCSR1 or LHCSR3 gene products and/or state 1–state 2 transitions or zeaxanthin accumulation, namely,npq4,stt7,stt7 npq4,npq4 lhcsr1,lhcsr3-complementednpq4 lhcsr1andnpq1, we showed that PSI undergoes NPQ through quenching of the associated LHCII antenna. This quenching event is fast-reversible on switching the light off, is mainly related to LHCSR3 activity, and is dependent on thylakoid luminal pH. Moreover, PSI quenching could also be observed in the absence of zeaxanthin or STT7 kinase activity.

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Wu, Pei, Qiusheng Kong, Jirong Bian, Golam Jalal Ahammed, Huimei Cui, Wei Xu, Zhifeng Yang, Jinxia Cui et Huiying Liu. « Unveiling Molecular Mechanisms of Nitric Oxide-Induced Low-Temperature Tolerance in Cucumber by Transcriptome Profiling ». International Journal of Molecular Sciences 23, n^o 10 (17 mai 2022) : 5615. http://dx.doi.org/10.3390/ijms23105615.

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Cucumber (Cucumis sativus L.) is one of the most popular cultivated vegetable crops but it is intrinsically sensitive to cold stress due to its thermophilic nature. To explore the molecular mechanism of plant response to low temperature (LT) and the mitigation effect of exogenous nitric oxide (NO) on LT stress in cucumber, transcriptome changes in cucumber leaves were compared. The results showed that LT stress regulated the transcript level of genes related to the cell cycle, photosynthesis, flavonoid accumulation, lignin synthesis, active gibberellin (GA), phenylalanine metabolism, phytohormone ethylene and salicylic acid (SA) signaling in cucumber seedlings. Exogenous NO improved the LT tolerance of cucumber as reflected by increased maximum photochemical efficiency (Fv/Fm) and decreased chilling damage index (CI), electrolyte leakage and malondialdehyde (MDA) content, and altered transcript levels of genes related to phenylalanine metabolism, lignin synthesis, plant hormone (SA and ethylene) signal transduction, and cell cycle. In addition, we found four differentially expressed transcription factors (MYB63, WRKY21, HD-ZIP, and b-ZIP) and their target genes such as the light-harvesting complex I chlorophyll a/b binding protein 1 gene (LHCA1), light-harvesting complex II chlorophyll a/b binding protein 1, 3, and 5 genes (LHCB1, LHCB3, and LHCB5), chalcone synthase gene (CSH), ethylene-insensitive protein 3 gene (EIN3), peroxidase, phenylalanine ammonia-lyase gene (PAL), DNA replication licensing factor gene (MCM5 and MCM6), gibberellin 3 beta-dioxygenase gene (GA3ox), and regulatory protein gene (NPRI), which are potentially associated with plant responses to NO and LT stress. Notably, HD-ZIP and b-ZIP specifically responded to exogenous NO under LT stress. Taken together, these results demonstrate that cucumber seedlings respond to LT stress and exogenous NO by modulating the transcription of some key transcription factors and their downstream genes, thereby regulating photosynthesis, lignin synthesis, plant hormone signal transduction, phenylalanine metabolism, cell cycle, and GA synthesis. Our study unveiled potential molecular mechanisms of plant response to LT stress and indicated the possibility of NO application in cucumber production under LT stress, particularly in winter and early spring.

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Kondo, Toru, Jesse B. Gordon, Alberta Pinnola, Luca Dall’Osto, Roberto Bassi et Gabriela S. Schlau-Cohen. « Microsecond and millisecond dynamics in the photosynthetic protein LHCSR1 observed by single-molecule correlation spectroscopy ». Proceedings of the National Academy of Sciences 116, n^o 23 (17 mai 2019) : 11247–52. http://dx.doi.org/10.1073/pnas.1821207116.

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Biological systems are subjected to continuous environmental fluctuations, and therefore, flexibility in the structure and function of their protein building blocks is essential for survival. Protein dynamics are often local conformational changes, which allows multiple dynamical processes to occur simultaneously and rapidly in individual proteins. Experiments often average over these dynamics and their multiplicity, preventing identification of the molecular origin and impact on biological function. Green plants survive under high light by quenching excess energy, and Light-Harvesting Complex Stress Related 1 (LHCSR1) is the protein responsible for quenching in moss. Here, we expand an analysis of the correlation function of the fluorescence lifetime by improving the estimation of the lifetime states and by developing a multicomponent model correlation function, and we apply this analysis at the single-molecule level. Through these advances, we resolve previously hidden rapid dynamics, including multiple parallel processes. By applying this technique to LHCSR1, we identify and quantitate parallel dynamics on hundreds of microseconds and tens of milliseconds timescales, likely at two quenching sites within the protein. These sites are individually controlled in response to fluctuations in sunlight, which provides robust regulation of the light-harvesting machinery. Considering our results in combination with previous structural, spectroscopic, and computational data, we propose specific pigments that serve as the quenching sites. These findings, therefore, provide a mechanistic basis for quenching, illustrating the ability of this method to uncover protein function.

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Correa-Galvis, Viviana, Petra Redekop, Katharine Guan, Annika Griess, Thuy B. Truong, Setsuko Wakao, Krishna K. Niyogi et Peter Jahns. « Photosystem II Subunit PsbS Is Involved in the Induction of LHCSR Protein-dependent Energy Dissipation in Chlamydomonas reinhardtii ». Journal of Biological Chemistry 291, n^o 33 (29 juin 2016) : 17478–87. http://dx.doi.org/10.1074/jbc.m116.737312.

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Non-photochemical quenching of excess excitation energy is an important photoprotective mechanism in photosynthetic organisms. In Arabidopsis thaliana, a high quenching capacity is constitutively present and depends on the PsbS protein. In the green alga Chlamydomonas reinhardtii, non-photochemical quenching becomes activated upon high light acclimation and requires the accumulation of light harvesting complex stress-related (LHCSR) proteins. Expression of the PsbS protein in C. reinhardtii has not been reported yet. Here, we show that PsbS is a light-induced protein in C. reinhardtii, whose accumulation under high light is further controlled by CO2 availability. PsbS accumulated after several hours of high light illumination at low CO2. At high CO2, however, PsbS was only transiently expressed under high light and was degraded after 1 h of high light exposure. PsbS accumulation correlated with an enhanced non-photochemical quenching capacity in high light-acclimated cells grown at low CO2. However, PsbS could not compensate for the function of LHCSR in an LHCSR-deficient mutant. Knockdown of PsbS accumulation led to reduction of both non-photochemical quenching capacity and LHCSR3 accumulation. Our data suggest that PsbS is essential for the activation of non-photochemical quenching in C. reinhardtii, possibly by promoting conformational changes required for activation of LHCSR3-dependent quenching in the antenna of photosystem II.

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Pinnola, Alberta, Leonardo Ghin, Elisa Gecchele, Matilde Merlin, Alessandro Alboresi, Linda Avesani, Mario Pezzotti, Stefano Capaldi, Stefano Cazzaniga et Roberto Bassi. « Heterologous Expression of Moss Light-harvesting Complex Stress-related 1 (LHCSR1), the Chlorophylla-Xanthophyll Pigment-protein Complex Catalyzing Non-photochemical Quenching, inNicotianasp. » Journal of Biological Chemistry 290, n^o 40 (10 août 2015) : 24340–54. http://dx.doi.org/10.1074/jbc.m115.668798.

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Dinc, Emine, Lijin Tian, Laura M. Roy, Robyn Roth, Ursula Goodenough et Roberta Croce. « LHCSR1 induces a fast and reversible pH-dependent fluorescence quenching in LHCII in Chlamydomonas reinhardtii cells ». Proceedings of the National Academy of Sciences 113, n^o 27 (22 juin 2016) : 7673–78. http://dx.doi.org/10.1073/pnas.1605380113.

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To avoid photodamage, photosynthetic organisms are able to thermally dissipate the energy absorbed in excess in a process known as nonphotochemical quenching (NPQ). Although NPQ has been studied extensively, the major players and the mechanism of quenching remain debated. This is a result of the difficulty in extracting molecular information from in vivo experiments and the absence of a validation system for in vitro experiments. Here, we have created a minimal cell of the green alga Chlamydomonas reinhardtii that is able to undergo NPQ. We show that LHCII, the main light harvesting complex of algae, cannot switch to a quenched conformation in response to pH changes by itself. Instead, a small amount of the protein LHCSR1 (light-harvesting complex stress related 1) is able to induce a large, fast, and reversible pH-dependent quenching in an LHCII-containing membrane. These results strongly suggest that LHCSR1 acts as pH sensor and that it modulates the excited state lifetimes of a large array of LHCII, also explaining the NPQ observed in the LHCSR3-less mutant. The possible quenching mechanisms are discussed.

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Allorent, Guillaume, Linnka Lefebvre-Legendre, Richard Chappuis, Marcel Kuntz, Thuy B. Truong, Krishna K. Niyogi, Roman Ulm et Michel Goldschmidt-Clermont. « UV-B photoreceptor-mediated protection of the photosynthetic machinery inChlamydomonas reinhardtii ». Proceedings of the National Academy of Sciences 113, n^o 51 (5 décembre 2016) : 14864–69. http://dx.doi.org/10.1073/pnas.1607695114.

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Life on earth is dependent on the photosynthetic conversion of light energy into chemical energy. However, absorption of excess sunlight can damage the photosynthetic machinery and limit photosynthetic activity, thereby affecting growth and productivity. Photosynthetic light harvesting can be down-regulated by nonphotochemical quenching (NPQ). A major component of NPQ is qE (energy-dependent nonphotochemical quenching), which allows dissipation of light energy as heat. Photodamage peaks in the UV-B part of the spectrum, but whether and how UV-B induces qE are unknown. Plants are responsive to UV-B via the UVR8 photoreceptor. Here, we report in the green algaChlamydomonas reinhardtiithat UVR8 induces accumulation of specific members of the light-harvesting complex (LHC) superfamily that contribute to qE, in particular LHC Stress-Related 1 (LHCSR1) and Photosystem II Subunit S (PSBS). The capacity for qE is strongly induced by UV-B, although the patterns of qE-related proteins accumulating in response to UV-B or to high light are clearly different. The competence for qE induced by acclimation to UV-B markedly contributes to photoprotection upon subsequent exposure to high light. Our study reveals an anterograde link between photoreceptor-mediated signaling in the nucleocytosolic compartment and the photoprotective regulation of photosynthetic activity in the chloroplast.

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Zada, Ahmad, Ahmad Ali, Dalal Nasser Binjawhar, Usama K. Abdel-Hameed, Azhar Hussain Shah, Shahid Maqsood Gill, Irtiza Hussain et al. « Molecular and Physiological Evaluation of Bread Wheat (Triticum aestivum L.) Genotypes for Stay Green under Drought Stress ». Genes 13, n^o 12 (30 novembre 2022) : 2261. http://dx.doi.org/10.3390/genes13122261.

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Water availability is considered as the main limiting factor of wheat growth illuminating the need of cultivars best adapted to drought situations for better wheat production and yield. Among these, the stay-green trait is thought to be related to the ability of wheat plants to maintain photosynthesis and CO2 assimilation, and a detailed molecular understanding of this trait may help in the selection of high-yielding, drought-tolerant wheats. The current study, therefore, evaluated the physiological responses of the selected wheat genotypes under pot-induced water stress conditions through different field capacities. The study also focused on exploring the molecular mechanisms involved in drought tolerance conferred due to the stay-green trait by studying the expression pattern of the selected PSI-associated light-harvesting complex I (LHC1) and PSII-associated LHCII gene families related to pigment-binding proteins. The results revealed that the studied traits, including relative water content, membrane stability index and chlorophyll, were variably and negatively affected, while the proline content was positively enhanced in the studied wheats under water stress treatments. Molecular diagnosis of the selected wheat genotypes using the expression profile of 06 genes, viz. TaLhca1, TaLhca2, TaLhca3, TaLhcb1, TaLhcb4 and TaLhcb6 that encodes for the LHCI and LHCII proteins, indicated variable responses to different levels of drought stress. The results obtained showed the relation between the genotypes and the severity of the drought stress condition. Among the studied genotypes, Chirya-1 and SD-28 performed well with a higher level of gene expression under drought stress conditions and may be used in genetic crosses to enrich the genetic background of common wheat against drought stress.

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Bailleul, B., A. Rogato, A. de Martino, S. Coesel, P. Cardol, C. Bowler, A. Falciatore et G. Finazzi. « An atypical member of the light-harvesting complex stress-related protein family modulates diatom responses to light ». Proceedings of the National Academy of Sciences 107, n^o 42 (4 octobre 2010) : 18214–19. http://dx.doi.org/10.1073/pnas.1007703107.

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Pinnola, Alberta. « The rise and fall of Light-Harvesting Complex Stress-Related proteins as photoprotection agents during evolution ». Journal of Experimental Botany 70, n^o 20 (2 août 2019) : 5527–35. http://dx.doi.org/10.1093/jxb/erz317.

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This review on the evolution of quenching mechanisms for excess energy dissipation focuses on the role of Light-Harvesting Complex Stress-Related (LHCSR) proteins versus Photosystem II Subunit S (PSBS) protein, and the reasons for the redundancy of LHCSR in vascular plants as PSBS became established.

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Pinnola, Alberta, Luca Dall’Osto, Caterina Gerotto, Tomas Morosinotto, Roberto Bassi et Alessandro Alboresi. « Zeaxanthin Binds to Light-Harvesting Complex Stress-Related Protein to Enhance Nonphotochemical Quenching in Physcomitrella patens ». Plant Cell 25, n^o 9 (septembre 2013) : 3519–34. http://dx.doi.org/10.1105/tpc.113.114538.

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Heddad, Mounia, et Iwona Adamska. « The Evolution of Light Stress Proteins in Photosynthetic Organisms ». Comparative and Functional Genomics 3, n^o 6 (2002) : 504–10. http://dx.doi.org/10.1002/cfg.221.

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The Elip (early light-inducible protein) family in pro- and eukaryotic photosynthetic organisms consists of more than 100 different stress proteins. These proteins accumulate in photosynthetic membranes in response to light stress and have photoprotective functions. At the amino acid level, members of the Elip family are closely related to light-harvesting chlorophylla/b-binding (Cab) antenna proteins of photosystem I and II, present in higher plants and some algae. Based on their predicted secondary structure, members of the Elip family are divided into three groups: (a) one-helix Hlips (high light-induced proteins), also called Scps (small Cab-like proteins) or Ohps (one-helix proteins); (b) two-helix Seps (stress-enhanced proteins); and (c) three-helix Elips and related proteins. Despite having different physiological functions it is believed that eukaryotic three-helix Cab proteins evolved from the prokaryotic Hlips through a series of duplications and fusions. In this review we analyse the occurrence of Elip family members in various photosynthetic prokaryotic and eukaryotic organisms and discuss their evolutionary relationship with Cab proteins.

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Giovagnetti, Vasco, et Alexander V. Ruban. « The evolution of the photoprotective antenna proteins in oxygenic photosynthetic eukaryotes ». Biochemical Society Transactions 46, n^o 5 (28 août 2018) : 1263–77. http://dx.doi.org/10.1042/bst20170304.

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Photosynthetic organisms require rapid and reversible down-regulation of light harvesting to avoid photodamage. Response to unpredictable light fluctuations is achieved by inducing energy-dependent quenching, qE, which is the major component of the process known as non-photochemical quenching (NPQ) of chlorophyll fluorescence. qE is controlled by the operation of the xanthophyll cycle and accumulation of specific types of proteins, upon thylakoid lumen acidification. The protein cofactors so far identified to modulate qE in photosynthetic eukaryotes are the photosystem II subunit S (PsbS) and light-harvesting complex stress-related (LHCSR/LHCX) proteins. A transition from LHCSR- to PsbS-dependent qE took place during the evolution of the Viridiplantae (also known as ‘green lineage’ organisms), such as green algae, mosses and vascular plants. Multiple studies showed that LHCSR and PsbS proteins have distinct functions in the mechanism of qE. LHCX(-like) proteins are closely related to LHCSR proteins and found in ‘red lineage’ organisms that contain secondary red plastids, such as diatoms. Although LHCX proteins appear to control qE in diatoms, their role in the mechanism remains poorly understood. Here, we present the current knowledge on the functions and evolution of these crucial proteins, which evolved in photosynthetic eukaryotes to optimise light harvesting.

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van Waasbergen, Lorraine G., Nadia Dolganov et Arthur R. Grossman. « nblS, a Gene Involved in Controlling Photosynthesis-Related Gene Expression during High Light and Nutrient Stress inSynechococcus elongatus PCC 7942 ». Journal of Bacteriology 184, n^o 9 (1 mai 2002) : 2481–90. http://dx.doi.org/10.1128/jb.184.9.2481-2490.2002.

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ABSTRACT The HliA protein of the cyanobacterium Synechococcus elongatus PCC 7942 is a small, thylakoid-associated protein that appears to play a role in photoprotection; its transcript rapidly accumulates in response to high-intensity light (HL) and the hli gene family is required for survival of cells in high light. In order to discover regulatory factors involved in HL acclimation in cyanobacteria, a screen was performed for chemically generated mutants unable to properly control expression of the hliA gene in response to HL. One such mutant was identified, and complementation analysis led to the identification of the affected gene, designated nblS. Based on its deduced protein sequence, NblS appears to be a membrane-bound, PAS-domain-bearing, sensor histidine kinase of two-component regulatory systems in bacteria. The nblS mutant was unable to properly control light intensity-mediated expression of several other photosynthesis-related genes, including all three psbA genes and the cpcBA genes. The mutant was also unable to control expression of the hliA and psbA genes in response to low-intensity blue/UV-A light, a response that may be related to the HL-mediated regulation of the genes. Additionally, in response to nutrient deprivation, the nblS mutant was unable to properly control accumulation of the nblA transcript and associated degradation of the light-harvesting phycobilisomes. The nblS mutant dies more rapidly than wild-type cells following exposure to HL or nutrient deprivation, likely due to its inability to properly acclimate to these stress conditions. Thus, the NblS protein is involved in the control of a number of processes critical for altering the photosynthetic apparatus in response to both HL and nutrient stress conditions.

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Yang, Young Nam, Thi Thuy Linh Le, Ji-Hye Hwang, Ismayil S. Zulfugarov, Eun-Ha Kim, Hyun Uk Kim, Jong-Seong Jeon, Dong-Hee Lee et Choon-Hwan Lee. « High Light Acclimation Mechanisms Deficient in a PsbS-Knockout Arabidopsis Mutant ». International Journal of Molecular Sciences 23, n^o 5 (28 février 2022) : 2695. http://dx.doi.org/10.3390/ijms23052695.

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The photosystem II PsbS protein of thylakoid membranes is responsible for regulating the energy-dependent, non-photochemical quenching of excess chlorophyll excited states as a short-term mechanism for protection against high light (HL) stress. However, the role of PsbS protein in long-term HL acclimation processes remains poorly understood. Here we investigate the role of PsbS protein during long-term HL acclimation processes in wild-type (WT) and npq4-1 mutants of Arabidopsis which lack the PsbS protein. During long-term HL illumination, photosystem II photochemical efficiency initially dropped, followed by a recovery of electron transport and photochemical quenching (qL) in WT, but not in npq4-1 mutants. In addition, we observed a reduction in light-harvesting antenna size during HL treatment that ceased after HL treatment in WT, but not in npq4-1 mutants. When plants were adapted to HL, more reactive oxygen species (ROS) were accumulated in npq4-1 mutants compared to WT. Gene expression studies indicated that npq4-1 mutants failed to express genes involved in plastoquinone biosynthesis. These results suggest that the PsbS protein regulates recovery processes such as electron transport and qL during long-term HL acclimation by maintaining plastoquinone biosynthetic gene expression and enhancing ROS homeostasis.

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Luciński, Robert, Lucyna Misztal, Sławomir Samardakiewicz et Grzegorz Jackowski. « The thylakoid protease Deg2 is involved in stress-related degradation of the photosystem II light-harvesting protein Lhcb6 in Arabidopsis thaliana ». New Phytologist 192, n^o 1 (13 juin 2011) : 74–86. http://dx.doi.org/10.1111/j.1469-8137.2011.03782.x.

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Andrade, Lidiane Maria, Caique Alves Tito, Camila Mascarenhas, Fabíola Aliaga Lima, Meriellen Dias, Cristiano José Andrade, Maria Anita Mendes et Claudio Augusto Oller Nascimento. « Phycoremediation of Copper by Chlorella protothecoides (UTEX 256) : Proteomics of Protein Biosynthesis and Stress Response ». Biomass 2, n^o 3 (23 juin 2022) : 116–29. http://dx.doi.org/10.3390/biomass2030008.

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Phycoremediation is an eco-friendly treatment for mining wastes. Copper at high concentrations is toxic for microalgae growth (bioremediation). Proteomics is a modern approach that can assist in elucidating, in detail, the highly complex metabolic mechanisms related to phycoremediation. Therefore, this study aimed to evaluate the effect of copper ions (Cu2+) on the metabolism of Chlorella protothecoides (UTEX 256), particularly the proteome changes. The WC culture medium supplemented with Cu2+ at 0.3, 0.6, and 0.9 mg/L showed a strict correlation to Cu2+ removal of 40, 33, and 36% of the initial content, respectively. In addition, Cu2+ concentrations did not affect microalgae growth—a very traditional approach to measuring toxicity. However, the proteomics data indicated that when compared to the control, reductions in protein levels were observed, and the 10 most scored proteins were related to the light-harvesting complex. Interestingly, C. protothecoides cultivated at 0.9 mg of Cu2+/L biosynthesized the protein Ycf3-interacting chloroplastic isoform X1 to respond to the photooxidative stress and the DNA-directed RNA polymerase III subunit RPC5 was related to the Cu2+ binding. Pre-mRNA-processing factor 19 and cytochrome c peroxidase proteins were observed only in the copper-containing treatments indicating the activation of antioxidant mechanisms by reactive oxygen species, which are potential environmental pollutant biomarkers.

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Wu, Jianghao, Liwei Rong, Weijun Lin, Lingxi Kong, Dengjie Wei, Lixin Zhang, Jean-David Rochaix et Xiumei Xu. « Functional redox links between lumen thiol oxidoreductase1 and serine/threonine-protein kinase STN7 ». Plant Physiology 186, n^o 2 (23 février 2021) : 964–76. http://dx.doi.org/10.1093/plphys/kiab091.

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Abstract In response to changing light quantity and quality, photosynthetic organisms perform state transitions, a process which optimizes photosynthetic yield and mitigates photo-damage. The serine/threonine-protein kinase STN7 phosphorylates the light-harvesting complex of photosystem II (PSII; light-harvesting complex II), which then migrates from PSII to photosystem I (PSI), thereby rebalancing the light excitation energy between the photosystems and restoring the redox poise of the photosynthetic electron transport chain. Two conserved cysteines forming intra- or intermolecular disulfide bonds in the lumenal domain (LD) of STN7 are essential for the kinase activity although it is still unknown how activation of the kinase is regulated. In this study, we show lumen thiol oxidoreductase 1 (LTO1) is co-expressed with STN7 in Arabidopsis (Arabidopsis thaliana) and interacts with the LD of STN7 in vitro and in vivo. LTO1 contains thioredoxin (TRX)-like and vitamin K epoxide reductase domains which are related to the disulfide-bond formation system in bacteria. We further show that the TRX-like domain of LTO1 is able to oxidize the conserved lumenal cysteines of STN7 in vitro. In addition, loss of LTO1 affects the kinase activity of STN7 in Arabidopsis. Based on these results, we propose that LTO1 helps to maintain STN7 in an oxidized active state in state 2 through redox interactions between the lumenal cysteines of STN7 and LTO1.

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Ballottari, Matteo, Thuy B. Truong, Eleonora De Re, Erika Erickson, Giulio R. Stella, Graham R. Fleming, Roberto Bassi et Krishna K. Niyogi. « Identification of pH-sensing Sites in the Light Harvesting Complex Stress-related 3 Protein Essential for Triggering Non-photochemical Quenching inChlamydomonas reinhardtii ». Journal of Biological Chemistry 291, n^o 14 (27 janvier 2016) : 7334–46. http://dx.doi.org/10.1074/jbc.m115.704601.

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Guzmán Mendoza, Naymel Alejandra, Kohei Homma, Hideto Osada, Eriko Toda, Norimitsu Ban, Norihiro Nagai, Kazuno Negishi, Kazuo Tsubota et Yoko Ozawa. « Neuroprotective Effect of 4-Phenylbutyric Acid against Photo-Stress in the Retina ». Antioxidants 10, n^o 7 (20 juillet 2021) : 1147. http://dx.doi.org/10.3390/antiox10071147.

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Exposure to excessive visible light causes retinal degeneration and may influence the progression of retinal blinding diseases. However, there are currently no applied treatments. Here, we focused on endoplasmic reticulum (ER) stress, which can cause cellular degeneration and apoptosis in response to stress. We analyzed functional, histological, and molecular changes in the light-exposed retina and the effects of administering an ER-stress inhibitor, 4-phenylbutyric acid (4-PBA), in mice. We found that light-induced visual function impairment related to photoreceptor cell loss and outer segment degeneration were substantially suppressed by 4-PBA administration, following attenuated photoreceptor apoptosis. Induction of retinal ER stress soon after light exposure, represented by upregulation of the immunoglobulin heavy chain binding protein (BiP) and C/EBP-Homologous Protein (CHOP), were suppressed by 4-PBA. Concurrently, light-induced oxidative stress markers, Nuclear factor erythroid 2–related factor 2 (Nrf2) and Heme Oxygenase 1 (HO-1), and mitochondrial apoptotic markers, B-cell lymphoma 2 apoptosis regulator (Bcl-2)-associated death promoter (Bad), and Bcl-2-associated X protein (Bax), were suppressed by 4-PBA administration. Increased expression of glial fibrillary acidic protein denoted retinal neuroinflammation, and inflammatory cytokines were induced after light exposure; however, 4-PBA acted as an anti-inflammatory. Suppression of ER stress by 4-PBA may be a new therapeutic approach to suppress the progression of retinal neurodegeneration and protect visual function against photo-stress.

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Sárvári, Éva, Ferenc Fodor, Edit Cseh, Anita Varga, Gyula Záray et Lello Zolla. « Relationship between Changes in Ion Content of Leaves and Chlorophyll-Protein Composition in Cucumber under Cd and Pb Stress ». Zeitschrift für Naturforschung C 54, n^o 9-10 (1 octobre 1999) : 746–53. http://dx.doi.org/10.1515/znc-1999-9-1021.

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Hydroponically cultured cucumber plants supplied with 4 μᴍ Fe chelated either with EDTA or citrate and treated with Cd (10 μᴍ) and Pb (10, 50 μᴍ) from their one- or fourleaf stage were grown up to five-week-old age. The decrease in the chlorophyll content was the most pronounced in plants treated with Cd from a younger age, and in the case of Fecitrate. The chlorophyll a/b ratio of Cd stressed plants was also significantly lowered. In later treated plants the accumulation of chlorophyll was inhibited and the chlorophyll a/b ratio decreased only in the vigorously growing young leaves. Pb treatment had only a slight effect on both parameters. The changes in the chlorophyll-protein pattern of thylakoids were strongly related to their chlorophyll content but the response of each complex was different. Cd reduced the amount of chlorophyll containing complexes in the order of photosystem I > light-harvesting complex II > photosystem Il-core, while light-harvesting complex II appeared somewhat more sensitive than photosystem I in Pb treated plants. In accordance, a decline or blue shift of the long wavelength fluorescence emission band of chloroplasts was observed referring to disturbances also in photosystem I antenna assembly. The accumulation of chlorophyll and chlorophyll-proteins did not show close relationship to the heavy metal content of leaves which was the highest in the first of the intensively expanding leaves in the time of the treatment. The extraordinary sensitivity of photosystem I, and the relative stability of photosystem II under Cd treatment were similar to the case found in iron deficient plants. However, the pattern of chlorophyll content of leaf storeys of Cd treated plants rather followed the changes in their Mn content

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Wang, Shengqi, Neng Wang, Yifeng Zheng, Jin Zhang, Fengxue Zhang et Zhiyu Wang. « Caveolin-1 : An Oxidative Stress-Related Target for Cancer Prevention ». Oxidative Medicine and Cellular Longevity 2017 (2017) : 1–20. http://dx.doi.org/10.1155/2017/7454031.

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Aberrant oxidative metabolism is one of the hallmarks of cancer. Reactive species overproduction could promote carcinogenesis via inducing genetic mutations and activating oncogenic pathways, and thus, antioxidant therapy was considered as an important strategy for cancer prevention and treatment. Caveolin-1 (Cav-1), a constituent protein of caveolae, has been shown to mediate tumorigenesis and progression through oxidative stress modulation recently. Reactive species could modulate the expression, degradation, posttranslational modifications, and membrane trafficking of Cav-1, while Cav-1-targeted treatments could scavenge the reactive species. More importantly, emerging evidences have indicated that multiple antioxidants could exert antitumor activities in cancer cells and protective activities in normal cells by modulating the Cav-1 pathway. Altogether, these findings indicate that Cav-1 may be a promising oxidative stress-related target for cancer antioxidant prevention. Elucidating the underlying interaction mechanisms between oxidative stress and Cav-1 is helpful for enhancing the preventive effects of antioxidants on cancer, for improving clinical outcomes of antioxidant-related therapeutics in cancer patients, and for developing Cav-1 targeted drugs. Herein, we summarize the available evidence of the roles of Cav-1 and oxidative stress in tumorigenesis and development and shed novel light on designing strategies for cancer prevention or treatment by utilizing the interaction mode between Cav-1 and oxidative stress.

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Shum, Fanny WF, Shanelle W. Ko, Yong-Seok Lee, Bong-Kiun Kaang et Min Zhuo. « Genetic Alteration of Anxiety and Stress-Like Behavior in Mice Lacking CaMKIV ». Molecular Pain 1 (1 janvier 2005) : 1744–8069. http://dx.doi.org/10.1186/1744-8069-1-22.

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Calcium-calmodulin-dependent protein kinase IV (CaMKIV) phosphorylates the major transcription factor cyclic AMP-response element binding protein (CREB), which plays a role in emotional behavior. Here, CaMKIV knockout mice ( CaMKIV−/−) were tested in a battery of stress and anxiety-related behavioral tests, to determine if CaMKIV plays a role in emotional behavior. CaMKIV−/−exhibited a decrease in anxiety-like behavior in both the elevated plus maze and dark-light emergence tests when compared to wild-type mice. Both the acoustic startle response and prepulse inhibition of startle were decreased with the deletion of CaMKIV. In addition, CaMKIV−/− mice displayed a lack of stress-induced analgesia following restraint or cold swim stress. Our results demonstrate a key role for CaMKIV in anxiety and stress-related behavior.

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Hong, Woo-Jong, Xu Jiang, Hye Ryun Ahn, Juyoung Choi, Seong-Ryong Kim et Ki-Hong Jung. « Systematic Analysis of Cold Stress Response and Diurnal Rhythm Using Transcriptome Data in Rice Reveals the Molecular Networks Related to Various Biological Processes ». International Journal of Molecular Sciences 21, n^o 18 (19 septembre 2020) : 6872. http://dx.doi.org/10.3390/ijms21186872.

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Rice (Oryza sativa L.), a staple crop plant that is a major source of calories for approximately 50% of the human population, exhibits various physiological responses against temperature stress. These responses are known mechanisms of flexible adaptation through crosstalk with the intrinsic circadian clock. However, the molecular regulatory network underlining this crosstalk remains poorly understood. Therefore, we performed systematic transcriptome data analyses to identify the genes involved in both cold stress responses and diurnal rhythmic patterns. Here, we first identified cold-regulated genes and then identified diurnal rhythmic genes from those (119 cold-upregulated and 346 cold-downregulated genes). We defined cold-responsive diurnal rhythmic genes as CD genes. We further analyzed the functional features of these CD genes through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses and performed a literature search to identify functionally characterized CD genes. Subsequently, we found that light-harvesting complex proteins involved in photosynthesis strongly associate with the crosstalk. Furthermore, we constructed a protein–protein interaction network encompassing four hub genes and analyzed the roles of the Stay-Green (SGR) gene in regulating crosstalk with sgr mutants. We predict that these findings will provide new insights in understanding the environmental stress response of crop plants against climate change.

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Terao, Ryo, Megumi Honjo, Takashi Ueta, Hideru Obinata, Takashi Izumi, Makoto Kurano, Yutaka Yatomi, Hideto Koso, Sumiko Watanabe et Makoto Aihara. « Light Stress-Induced Increase of Sphingosine 1-Phosphate in Photoreceptors and Its Relevance to Retinal Degeneration ». International Journal of Molecular Sciences 20, n^o 15 (26 juillet 2019) : 3670. http://dx.doi.org/10.3390/ijms20153670.

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Sphingosine 1-phosphate (S1P) is a potent lipid mediator that modulates inflammation and angiogenesis. In this study, we investigated the possible involvement of S1P in the pathology of light-induced retinal degeneration in vivo and in vitro. The intracellular S1P and sphingosine kinase (SphK) activity in a photoreceptor cell line (661W cells) was significantly increased by exposure to light. The enhancement of SphK1 expression was dependent on illumination, and all-trans-retinal significantly promoted SphK1 expression. S1P treatment reduced protein kinase B (Akt) phosphorylation and increased the protein expression of cleaved caspase-3, and induced photoreceptor cell apoptosis. In vivo, light exposure enhanced the expression of SphK1 in the outer segments of photoreceptors. Intravitreal injection of a SphK inhibitor significantly suppressed the thinning of the outer nuclear layer and ameliorated the attenuation of the amplitudes of a-waves and b-waves of electroretinograms during light-induced retinal degeneration. These findings imply that light exposure induces the synthesis of S1P in photoreceptors by upregulating SphK1, which is facilitated by all-trans-retinal, causing retinal degeneration. Inhibition of this enhancement may be a therapeutic target of outer retinal degeneration, including age-related macular degeneration.

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Raven, J. A., J. E. Kübler et J. Beardall. « Put out the light, and then put out the light ». Journal of the Marine Biological Association of the United Kingdom 80, n^o 1 (février 2000) : 1–25. http://dx.doi.org/10.1017/s0025315499001526.

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The lowest photon flux density of photosynthetically active radiation at which O2-evolving marine photolithotrophs appear to be able to grow is some 10 nmol photon m−2 s−1, while marine non-O2-evolvers can grow at 4 nmol photon m−2 s−1, in both cases with the photon flux density averaged over the 24 hour L:D cycle. Constraints on the ability to grow at very low fluxes of photosynthetically active radiation fall into three categories. Category one includes essential processes whose efficiency is independent of the rate of energy input, but whose catalysts show phylogenetic variation leading to different energy costs for a given process in different taxa, e.g. light-harvesting complexes, RUBISCO and probably in the sensitivity of PsII to photodamage. The second category comprises essential processes whose efficiency decreases with decreasing energy input rate as a result of back-reactions independent of the energy input rate, e.g. charge recombination following charge separation by PsII and short-circuit H+ fluxes across the thylakoid membrane which decrease the fraction of pumped H+ which can be used in adenosine diphosphate phosphorylation. Category two also includes that component of protein turnover which cannot be related to replacement of polypeptides which were incorrectly assembled following uncorrected errors of transcription or translation, or which were damaged by processes whose rate increases with increasing energy input rate such as photodamage to PsII. The third category includes only O2-dependent damage to the D1 protein of PsII whose rate increases with a decreasing incident flux of photosynthetically active radiation. Processes in categories two and three are most likely to impose the lower limit on the photon flux density which can support photolithotrophic growth. The available literature, mainly on organisms which are not adapted to growth at very low photon flux densities, suggests that three major limitations (charge recombination in PsII, H+ leakage and slippage, and protein turnover) can individually impose lower limits in excess of 20 nmol photon m−2 s−1 on photolithotrophic growth. Furthermore, these three limitations are interactive, so that considering all three processes acting in series leads to an even higher predicted lower photon flux density limit for photolithotrophic growth.

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Che, Yufen, Shoko Kusama, Shintaro Matsui, Marjaana Suorsa, Takeshi Nakano, Eva-Mari Aro et Kentaro Ifuku. « Arabidopsis PsbP-Like Protein 1 Facilitates the Assembly of the Photosystem II Supercomplexes and Optimizes Plant Fitness under Fluctuating Light ». Plant and Cell Physiology 61, n^o 6 (11 avril 2020) : 1168–80. http://dx.doi.org/10.1093/pcp/pcaa045.

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Abstract In green plants, photosystem II (PSII) forms multisubunit supercomplexes (SCs) containing a dimeric core and light-harvesting complexes (LHCs). In this study, we show that Arabidopsis thaliana PsbP-like protein 1 (PPL1) is involved in the assembly of the PSII SCs and is required for adaptation to changing light intensity. PPL1 is a homolog of PsbP protein that optimizes the water-oxidizing reaction of PSII in green plants and is required for the efficient repair of photodamaged PSII; however, its exact function has been unknown. PPL1 was enriched in stroma lamellae and grana margins and associated with PSII subcomplexes including PSII monomers and PSII dimers, and several LHCII assemblies, while PPL1 was not detected in PSII–LHCII SCs. In a PPL1 null mutant (ppl1-2), assembly of CP43, PsbR and PsbW was affected, resulting in a reduced accumulation of PSII SCs even under moderate light intensity. This caused the abnormal association of LHCII in ppl1-2, as indicated by lower maximal quantum efficiency of PSII (Fv/Fm) and accelerated State 1 to State 2 transitions. These differences would lower the capability of plants to adapt to changing light environments, thereby leading to reduced growth under natural fluctuating light environments. Phylogenetic and structural analyses suggest that PPL1 is closely related to its cyanobacterial homolog CyanoP, which functions as an assembly factor in the early stage of PSII biogenesis. Our results suggest that PPL1 has a similar function, but the data also indicate that it could aid the association of LHCII with PSII.

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Pan-utai, Wanida, Siriluck Iamtham, Sittiruk Roytrakul, Sarn Settachaimongkon, Ladda Sangduean Wattanasiritham, Sumitra Boonbumrung, Juta Mookdasanit et Sayamon Sithtisarn. « Arthrospira platensis Mutagenesis for Protein and C-Phycocyanin Improvement and Proteomics Approaches ». Life 12, n^o 6 (17 juin 2022) : 911. http://dx.doi.org/10.3390/life12060911.

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Arthrospira (Spirulina) platensis is known for its use as a food supplement, with reported therapeutic properties including antiviral, anti-inflammatory and antioxidant activity. Arthrospira is also an excellent source of proteins and C-phycocyanin. The latter is a light-harvesting pigment-protein complex in cyanobacteria, located on the outer surface of the thylakoid membrane and comprising 40 to 60% of the total soluble protein in cells. Random mutagenesis is a useful tool as a non-genetically modified mutation method that has been widely used to generate mutants of different microorganisms. Exposure of microalgae or cyanobacteria to chemical stimuli affects their growth and many biological processes. Chemicals influence several proteins, including those involved in carbohydrate and energy metabolisms, photosynthesis and stress-related proteins (oxidative stress-reactive oxygen species (ROS) scavenging enzymes). Signal transduction pathways and ion transportation mechanisms are also impacted by chemical treatment, with changes causing the production of numerous biomolecules and stimulation of defence responses. This study compared the protein contents of A. platensis control and after mutagenesis using diethyl sulphate (DES) under various treatment concentrations for effective mutation of A. platensis. Results identified 1152 peptides using proteomics approaches. The proteins were classified into 23 functional categories. Random mutagenesis of A. platensis by DES was found to be highly effective for C-phycocyanin and protein production.

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Nishioka, Keiji, Yusuke Kato, Shin-ichiro Ozawa, Yuichiro Takahashi et Wataru Sakamoto. « Phos-tag-based approach to study protein phosphorylation in the thylakoid membrane ». Photosynthesis Research 147, n^o 1 (2 décembre 2020) : 107–24. http://dx.doi.org/10.1007/s11120-020-00803-1.

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AbstractProtein phosphorylation is a fundamental post-translational modification in all organisms. In photoautotrophic organisms, protein phosphorylation is essential for the fine-tuning of photosynthesis. The reversible phosphorylation of the photosystem II (PSII) core and the light-harvesting complex of PSII (LHCII) contribute to the regulation of photosynthetic activities. Besides the phosphorylation of these major proteins, recent phosphoproteomic analyses have revealed that several proteins are phosphorylated in the thylakoid membrane. In this study, we utilized the Phos-tag technology for a comprehensive assessment of protein phosphorylation in the thylakoid membrane of Arabidopsis. Phos-tag SDS-PAGE enables the mobility shift of phosphorylated proteins compared with their non-phosphorylated isoform, thus differentiating phosphorylated proteins from their non-phosphorylated isoforms. We extrapolated this technique to two-dimensional (2D) SDS-PAGE for detecting protein phosphorylation in the thylakoid membrane. Thylakoid proteins were separated in the first dimension by conventional SDS-PAGE and in the second dimension by Phos-tag SDS-PAGE. In addition to the isolation of major phosphorylated photosynthesis-related proteins, 2D Phos-tag SDS-PAGE enabled the detection of several minor phosphorylated proteins in the thylakoid membrane. The analysis of the thylakoid kinase mutants demonstrated that light-dependent protein phosphorylation was mainly restricted to the phosphorylation of the PSII core and LHCII proteins. Furthermore, we assessed the phosphorylation states of the structural domains of the thylakoid membrane, grana core, grana margin, and stroma lamella. Overall, these results demonstrated that Phos-tag SDS-PAGE is a useful biochemical tool for studying in vivo protein phosphorylation in the thylakoid membrane protein.

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Yuan, Zhongxun, Xilu Ni, Muhammad Arif, Zhi Dong, Limiao Zhang, Xue Tan, Jiajia Li et Changxiao Li. « Transcriptomic Analysis of the Photosynthetic, Respiration, and Aerenchyma Adaptation Strategies in Bermudagrass (Cynodon dactylon) under Different Submergence Stress ». International Journal of Molecular Sciences 22, n^o 15 (23 juillet 2021) : 7905. http://dx.doi.org/10.3390/ijms22157905.

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Submergence impedes photosynthesis and respiration but facilitates aerenchyma formation in bermudagrass. Still, the regulatory genes underlying these physiological responses are unclear in the literature. To identify differentially expressed genes (DEGs) related to these physiological mechanisms, we studied the expression of DEGs in aboveground and underground tissues of bermudagrass after a 7 d treatment under control (CK), shallow submergence (SS), and deep submergence (DS). Results show that compared with CK, 12276 and 12559 DEGs were identified under SS and DS, respectively. Among them, the DEGs closely related to the metabolism of chlorophyll biosynthesis, light-harvesting, protein complex, and carbon fixation were down-regulated in SS and DS. Meanwhile, a large number of DEGs involved in starch and sucrose hydrolase activities, glycolysis/gluconeogenesis, tricarboxylic acid (TCA) cycle, and oxidative phosphorylation were down-regulated in aboveground tissues of bermudagrass in SS and DS. Whereas in underground tissues of bermudagrass these DEGs were all up-regulated under SS, only beta-fructofuranosidase and α-amylase related genes were up-regulated under DS. In addition, we found that DEGs associated with ethylene signaling, Ca2+-ROS signaling, and cell wall modification were also up-regulated during aerenchyma formation in underground tissues of bermudagrass under SS and DS. These results provide the basis for further exploration of the regulatory and functional genes related to the adaptability of bermudagrass to submergence.

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Shi, Wenjiao, Zhixin Guo et Ruixia Yuan. « Testicular Injury Attenuated by Rapamycin Through Induction of Autophagy and Inhibition of Endoplasmic Reticulum Stress in Streptozotocin- Induced Diabetic Rats ». Endocrine, Metabolic & ; Immune Disorders - Drug Targets 19, n^o 5 (3 juin 2019) : 665–75. http://dx.doi.org/10.2174/1871530319666190102112844.

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Background and Objective: This study investigated whether rapamycin has a protective effect on the testis of diabetic rats by regulating autophagy, endoplasmic reticulum stress, and oxidative stress. Methods: Thirty male Sprague-Dawley rats were randomly divided into three groups: control, diabetic, and diabetic treated with rapamycin, which received gavage of rapamycin (2mg.kg-1.d-1) after induction of diabetes. Diabetic rats were induced by intraperitoneal injection of streptozotocin (STZ, 65mg.Kg-1). All rats were sacrificed at the termination after 8 weeks of rapamycin treatment. The testicular pathological changes were determined by hematoxylin and eosin staining. The protein or mRNA expression of autophagy-related proteins (Beclin1, microtubule-associated protein light chain 3 (LC3), p62), ER stress marked proteins (CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), caspase-12), oxidative stress-related proteins (p22phox, nuclear factor erythroid2-related factor 2 (Nrf2)) and apoptosis-related proteins (Bax, B cell lymphoma-2 (Bcl-2)) were assayed by western blot or real-time fluorescence quantitative PCR. Results: There were significant pathological changes in the testes of diabetic rats. The expression of Beclin1, LC3, Nrf2, Bcl-2 were significantly decreased and p62, CHOP, caspase12, p22phox, and Bax were notably increased in the testis of diabetic rats (P <0.05). However, rapamycin treatment for 8 weeks significantly reversed the above changes in the testis of diabetic rats (P <0.05). Conclusion: Rapamycin appears to produce a protective effect on the testes of diabetic rats by inducing the expression of autophagy and inhibiting the expression of ER-stress, oxidative stress, and apoptosis.

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Wu, Yi-Chia, Wei-Ting Wang, Su-Shin Lee, Yur-Ren Kuo, Ya-Chin Wang, Shih-Jung Yen, Mei-Yueh Lee et Jwu-Lai Yeh. « Glucagon-Like Peptide-1 Receptor Agonist Attenuates Autophagy to Ameliorate Pulmonary Arterial Hypertension through Drp1/NOX- and Atg-5/Atg-7/Beclin-1/LC3β Pathways ». International Journal of Molecular Sciences 20, n^o 14 (12 juillet 2019) : 3435. http://dx.doi.org/10.3390/ijms20143435.

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Mitochondrial dysfunction is associated with cardiovascular diseases and diabetes. Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling, and the abnormal proliferation, apoptosis and migration of pulmonary arterial smooth muscle cells (PASMCs). The glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, has been shown to prevent pulmonary hypertension in monocrotaline-exposed rats. The aim of this study was to investigate the effect of liraglutide on autophagy, mitochondrial stress and apoptosis induced by platelet-derived growth factor BB (PDGF-BB). PASMCs were exposed to PDGF-BB, and changes in mitochondrial morphology, fusion-associated protein markers, and reactive oxygen species (ROS) production were examined. Autophagy was assessed according to the expressions of microtubule-associated protein light chain 3 (LC3)-II, LC3 puncta and Beclin-1. Western blot analysis was used to assess apoptosis, mitochondrial stress and autophagy markers. Liraglutide significantly inhibited PDGF-BB proliferation, migration and motility in PASMCs. PDGF-BB-induced ROS production was mitigated by liraglutide. Liraglutide increased the expression of α-smooth muscle actin (α-SMA) and decreased the expression of p-Yes-associated protein (p-YAP), inhibited autophagy-related protein (Atg)-5, Atg-7, Beclin-1 and the formation of LC3-β and mitochondrial fusion protein dynamin-related (Drp)1. Therefore, liraglutide can mitigate the proliferation of PASMCs via inhibiting cellular Drp1/nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) pathways and Atg-5/Atg-7/Beclin-1/LC3β-dependent pathways of autophagy in PAH.

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Zagórska, Anna, Eulalia Pozo-Guisado, Jérôme Boudeau, Alberto C. Vitari, Fatema H. Rafiqi, Jacob Thastrup, Maria Deak et al. « Regulation of activity and localization of the WNK1 protein kinase by hyperosmotic stress ». Journal of Cell Biology 176, n^o 1 (26 décembre 2006) : 89–100. http://dx.doi.org/10.1083/jcb.200605093.

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Mutations within the WNK1 (with-no-K[Lys] kinase-1) gene cause Gordon's hypertension syndrome. Little is known about how WNK1 is regulated. We demonstrate that WNK1 is rapidly activated and phosphorylated at multiple residues after exposure of cells to hyperosmotic conditions and that activation is mediated by the phosphorylation of its T-loop Ser382 residue, possibly triggered by a transautophosphorylation reaction. Activation of WNK1 coincides with the phosphorylation and activation of two WNK1 substrates, namely, the protein kinases STE20/SPS1-related proline alanine–rich kinase (SPAK) and oxidative stress response kinase-1 (OSR1). Small interfering RNA depletion of WNK1 impairs SPAK/OSR1 activity and phosphorylation of residues targeted by WNK1. Hyperosmotic stress induces rapid redistribution of WNK1 from the cytosol to vesicular structures that may comprise trans-Golgi network (TGN)/recycling endosomes, as they display rapid movement, colocalize with clathrin, adaptor protein complex 1 (AP-1), and TGN46, but not the AP-2 plasma membrane–coated pit marker nor the endosomal markers EEA1, Hrs, and LAMP1. Mutational analysis suggests that the WNK1 C-terminal noncatalytic domain mediates vesicle localization. Our observations shed light on the mechanism by which WNK1 is regulated by hyperosmotic stress.

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Dusza, Magdalena, Maciej Sporysz, Dorota Sokołowska et Katarzyna Grotkiewicz. « Impact of Post-Harvest Processing and Storing of Potato Tubers on Toxic Compounds Accumulation ». Agricultural Engineering 24, n^o 2 (1 juin 2020) : 39–44. http://dx.doi.org/10.1515/agriceng-2020-0015.

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AbstractDespite a long-term reduction trend, the potato production in Poland compared to EU countries is still very high. Therefore, the aim of the paper was to investigate the impact of mechanical damages and light for various genotypes on glycoalkaloids accumulation. Glycoalkaloids are toxic steroid glycosides that naturally occur in the family of Solanaceae. According to many authors, their presence in plants is related to resistance to a physiological stress inflicted by mechanical damages and infections caused by some microorganisms and insects. The TGA content above 200 mg∙kg−1 in a fresh mass of potatoes is an upper limit that guarantees health safety of food. Studies were carried out on 28 potato cultivars divided into 4 groups. The studies that were carried out after harvesting and after 5 months of storage in the experimental storage room in the temperature of 8°C showed an impact of damages and exposition to light of potato tubers on the content of glycoalkaloids.

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Jackowski, Grzegorz. « Senescence-Related Changes in the Subcomplex Arrangement of the Major Light-Harvesting Chlorophyll a/b-Protein Complex of Photosystem II (LHCII) as Influenced by Cytokinin ». Zeitschrift für Naturforschung C 51, n^o 7-8 (1 août 1996) : 464–72. http://dx.doi.org/10.1515/znc-1996-7-803.

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Abstract The major light-harvesting chlorophyll a /b -protein complex of photosystem II (LHCII) from fresh barley leaves could be resolved by non-denaturing IEF into five trimeric subcomplexes designated 1 -5 in order of decrasing pi value. IEF-based analysis of PSII particles isolated from leaves in which the processes of senescence were induced by detachement and dark-incubation in the presence of water for 0 -8 days let us reveal that substantial rearrangements of LHCII organization took place throughout the course of senescence comprising a step-wise decline in relative abundance of subcomplexes 1 -3 (down to 0-58% of the initial abundance during 8 days of aging) and an increase in the relative abundance of the subcomplexes 4 and 5. Using SDS-PAGE and immunoblot analysis it was shown that the rearrangements were linked to the changes in the relative levels of LHCII apoproteins i.e. 26.7 and 25.6 kDa ones. The changes comprised the preferential disappearance of the 26.7 kDa polypeptide and an enrichment of 25.6 kD a one and most probably reflect the hetero geneity among LHCII apoproteins concerning their stability under the conditions of chi loss. Kinetin was able to repress the senescence-related rearrangements in LHCII subcomplex organization at late stages of aging (5 -8 days) by preventing over this time period the disappearance of 26.7 kD a polypeptide and the enrichement of 25.6 kDa one.

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Qi, Yafei, Xiaomin Wang, Pei Lei, Huimin Li, Liru Yan, Jun Zhao, Jingjing Meng et al. « The chloroplast metalloproteases VAR2 and EGY1 act synergistically to regulate chloroplast development in Arabidopsis ». Journal of Biological Chemistry 295, n^o 4 (13 décembre 2019) : 1036–46. http://dx.doi.org/10.1074/jbc.ra119.011853.

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Chloroplast development and photosynthesis require the proper assembly and turnover of photosynthetic protein complexes. Chloroplasts harbor a repertoire of proteases to facilitate proteostasis and development. We have previously used an Arabidopsis leaf variegation mutant, yellow variegated2 (var2), defective in thylakoid FtsH protease complexes, as a tool to dissect the genetic regulation of chloroplast development. Here, we report a new genetic enhancer mutant of var2, enhancer of variegation3–1 (evr3–1). We confirm that EVR3 encodes a chloroplast metalloprotease, reported previously as ethylene-dependent gravitropism-deficient and yellow-green1 (EGY1)/ammonium overly sensitive1 (AMOS1). We observed that mutations in EVR3/EGY1/AMOS1 cause more severe leaf variegation in var2–5 and synthetic lethality in var2–4. Using a modified blue-native PAGE system, we reveal abnormal accumulations of photosystem I, photosystem II, and light-harvesting antenna complexes in EVR3/EGY1/AMOS1 mutants. Moreover, we discover distinct roles of VAR2 and EVR3/EGY1/AMOS1 in the turnover of photosystem II reaction center under high light stress. In summary, our findings indicate that two chloroplast metalloproteases, VAR2/AtFtsH2 and EVR3/EGY1/AMOS1, function coordinately to regulate chloroplast development and reveal new roles of EVR3/EGY1/AMOS1 in regulating chloroplast proteostasis in Arabidopsis.

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Li, Yang, Miao Sun, Fuyang Cao, Yu Chen, Linlin Zhang, Hao Li, Jiangbei Cao et al. « The Ferroptosis Inhibitor Liproxstatin-1 Ameliorates LPS-Induced Cognitive Impairment in Mice ». Nutrients 14, n^o 21 (1 novembre 2022) : 4599. http://dx.doi.org/10.3390/nu14214599.

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CNS inflammation is known to be an important pathogenetic mechanism of perioperative neurocognitive disorder (PND), and iron overload was reported to participate in this process accompanied by oxidative stress. Ferroptosis is an iron-dependent form of cell death, and occurs in multiple neurodegenerative diseases with cognitive disorder. However, the effect of ferroptosis in inflammation-related PND is unknown. In this study, we found that the ferroptosis inhibitor liproxstatin-1 ameliorated memory deficits in the mouse model of lipopolysaccharide (LPS)-induced cognitive impairment. Moreover, liproxstatin-1 decreased the activation of microglia and the release of interleukin (IL)-6 and tumor necrosis factor-alpha (TNF)-α, attenuated oxidative stress and lipid peroxidation, and further weakened mitochondrial injury and neuronal damage after LPS exposure. Additionally, the protective effect of liproxstatin-1 was related to the alleviation of iron deposition and the regulation of the ferroptosis-related protein family TF, xCT, Fth, Gpx4, and FtMt. These findings enhance our understanding of inflammation-involved cognitive dysfunction and shed light on future preclinical studies.

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Kaňa, Radek, Gábor Steinbach, Roman Sobotka, György Vámosi et Josef Komenda. « Fast Diffusion of the Unassembled PetC1-GFP Protein in the Cyanobacterial Thylakoid Membrane ». Life 11, n^o 1 (29 décembre 2020) : 15. http://dx.doi.org/10.3390/life11010015.

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Biological membranes were originally described as a fluid mosaic with uniform distribution of proteins and lipids. Later, heterogeneous membrane areas were found in many membrane systems including cyanobacterial thylakoids. In fact, cyanobacterial pigment–protein complexes (photosystems, phycobilisomes) form a heterogeneous mosaic of thylakoid membrane microdomains (MDs) restricting protein mobility. The trafficking of membrane proteins is one of the key factors for long-term survival under stress conditions, for instance during exposure to photoinhibitory light conditions. However, the mobility of unbound ‘free’ proteins in thylakoid membrane is poorly characterized. In this work, we assessed the maximal diffusional ability of a small, unbound thylakoid membrane protein by semi-single molecule FCS (fluorescence correlation spectroscopy) method in the cyanobacterium Synechocystis sp. PCC6803. We utilized a GFP-tagged variant of the cytochrome b6f subunit PetC1 (PetC1-GFP), which was not assembled in the b6f complex due to the presence of the tag. Subsequent FCS measurements have identified a very fast diffusion of the PetC1-GFP protein in the thylakoid membrane (D = 0.14 − 2.95 µm2s−1). This means that the mobility of PetC1-GFP was comparable with that of free lipids and was 50–500 times higher in comparison to the mobility of proteins (e.g., IsiA, LHCII—light-harvesting complexes of PSII) naturally associated with larger thylakoid membrane complexes like photosystems. Our results thus demonstrate the ability of free thylakoid-membrane proteins to move very fast, revealing the crucial role of protein–protein interactions in the mobility restrictions for large thylakoid protein complexes.

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Herawati, Irma Erika, Ronny Lesmana, Jutti Levita et Anas Subarnas. « INTERAKSI MOLEKULAR DARI RICIN-A DENGAN Beclin-1, LC3, DAN p62 PADA PROSES AUTOFAGI ». Jurnal Ilmiah Farmako Bahari 13, n^o 1 (31 janvier 2022) : 22. http://dx.doi.org/10.52434/jfb.v13i1.1450.

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Autofagi merupakan proses adaptasi yang dilakukan sebagai pertahanan dalam respon seluler, seperti kekurangan nutrisi atau stress metabolik lain. Mekanisme autofagi diregulasi oleh protein yang dinamakan Autophagy-Related Genes (ATG). Autofagi juga telah banyak dikaitkan dengan berbagai penyakit pada manusia, misalnya kanker atau penyakit degeneratif lainnya. Ricin merupakan protein toksik yang berasal dari biji jarak Ricinus communis L. dan banyak dieksplorasi untuk aktivitas antikanker melalui jalur pensinyalan caspase (apoptosis), namun belum ada penelitian pada jalur autofagi. Penelitian ini dilakukan untuk menelaah mode ikatan yang terjadi antara ricin-A dan protein-protein yang berperan pada setiap tahap proses autofagi (Beclin-1, LC3 atau Light Chain 3, dan p62/Sequistrosome1). Metode yang digunakan adalah simulasi penambatan protein-protein menggunakan server online ClusPro (https://cluspro.org). Hasil penelitian menunjukkan bahwa ricin-A dapat berinteraksi dengan Beclin-1. LC3, dan p62 melalui pembentukan ikatan hidrogen dengan afinitas baik. Dapat disimpulkan bahwa ricin-A berperan penting dalam proses autofagi dan dapat dikembangkan menjadi fitofarmaka terapi kanker.

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Rathgeber, Christopher, Natalia Yurkova, Erko Stackebrandt, Peter Schumann, J. Thomas Beatty et Vladimir Yurkov. « Roseicyclus mahoneyensis gen. nov., sp. nov., an aerobic phototrophic bacterium isolated from a meromictic lake ». International Journal of Systematic and Evolutionary Microbiology 55, n^o 4 (1 juillet 2005) : 1597–603. http://dx.doi.org/10.1099/ijs.0.63195-0.

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Eight strains of Gram-negative bacteria able to form ring-like cells were isolated from Mahoney Lake, a meromictic lake in south-central British Columbia, Canada. All strains were pink–purple and contained bacteriochlorophyll a incorporated into the light-harvesting 1 and 2 and reaction-centre pigment–protein complexes. Growth did not occur anaerobically under illuminated conditions; these strains were obligately aerobic, prompting their designation as members of the aerobic phototrophic bacteria. Physiological characterization revealed that these isolates share a similar tolerance to high levels of salinity and pH, as would be expected of bacteria from a highly saline lake; however, the strains exhibited marked differences in their ability to utilize organic substrates for aerobic heterotrophic growth. 16S rRNA sequence analysis showed that the strains are closely related to members of the non-phototrophic genera Octadecabacter (92·0–92·9 %) and Ketogulonicigenium (92·2–92·6 %), as well as to aerobic phototrophs of the genera Roseivivax (92·2–92·9 %) and Roseovarius (91·7–92·4 %) within the ‘Alphaproteobacteria’. The DNA G+C content was 66·2 mol%. The unusual light-harvesting complex 2, the distinct morphological features and physiological traits of these strains as well as the phylogenetic data support the proposal of the novel genus and species Roseicyclus mahoneyensis gen. nov., sp. nov., with ML6T (=DSM 16097T=VKM B-2346T) as the type strain.

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Yang, Eun Jin. « A Novel Supplement Attenuates Oxidative Stress-Induced TDP-43-Related Pathogenesis in TDP-43-Expressed Cells ». Evidence-Based Complementary and Alternative Medicine 2021 (27 septembre 2021) : 1–9. http://dx.doi.org/10.1155/2021/6773260.

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Amyotrophic lateral sclerosis (ALS) is caused by selective the loss of spinal motor neurons by multifactorial pathological mechanisms and results in muscle atrophy. Incidence rates of ALS are increasing over time, but there are no effective treatments at present due to limitations on approved therapies (riluzole and edaravone). Therefore, this study investigated whether combined treatment with Bojungikgi-tang and riluzole could act synergistically in transactive response DNA-binding protein 43 (TDP-43) stress granule cells. To examine the effect of combined treatment on oxidative stress-induced cell death, the CCK8 assay was performed for the detection of cell viability. The expression of oxidative stress-induced proteins was determined by Western blot. Quantification of sodium arsenite-induced reactive oxygen species (ROS) was measured in TDP-43 stress granular cells using 2,7-diacetyl dichlorofluorescein diacetate. To investigate the effect of combined treatment on TDP-43 aggregation, immunofluorescence and immunoblotting were performed in TDP-43 stress granular cells. This combined treatment alleviated oxidative stress-induced cell death by increasing the expression levels of antioxidation proteins, such as heme oxygenase-1 and B cell lymphoma-2-associated X protein. Furthermore, it reduced oxidative stress-induced TDP-43 aggregates and lowered the levels of autophagy-related proteins, including p62, light chain 3b, and ATG8, in TDP-43-expressing cells. Our results suggest that this combined treatment could be helpful for autophagy regulation in other neurodegenerative diseases.

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Miller, A. Raymond, Thomas J. Kelley et Brian D. White. « Nondestructive Evaluation of Pickling Cucumbers Using Visible-Infrared Light Transmission ». Journal of the American Society for Horticultural Science 120, n^o 6 (novembre 1995) : 1063–68. http://dx.doi.org/10.21273/jashs.120.6.1063.

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A nondestructive method was developed utilizing a modified Trebor 101 watercore tester to evaluate the internal quality of pickling cucumbers. The method involved measuring the relative amount of visible-infrared light passing through the longitudinal midsection of whole cucumber fruit. Light transmission was quantified on a unitless sigmoid scale from 1 to 10, with light transmission and scale values positively related. Immediately after hand harvest, size 3F (47 to 51 mm in diameter) cucumbers exhibited transmission values between 2 and 3, regardless of cultivar. Following a mechanical-stress treatment, which simulated bruising incurred during harvesting and handling of cucumbers, the internal quality of the fruit declined and was associated with an increase to a value of 6 in light transmission compared to non-stressed fruit. Light transmission increased as the severity of stress applied to the fruit increased, and high light transmission values were evident throughout a 48 h storage period at room temperature. Light transmission values increased as fruit diameter decreased, but values within a particular size class of undamaged, hand-harvested fruit were consistent. Machine-harvested fruit (size 3F), evaluated just before processing, exhibited light transmission values from 2 to 8, but the majority of fruit fell within the transmission range of 2 to 3. When fruit exhibiting different light transmission values were speared (cut longitudinally into sixths), processed, and then visually evaluated by panelists, spears prepared from fruit exhibiting high transmission values were judged to be of lower quality than those prepared from fruit exhibiting low transmission values. Visible-infrared light transmission may be a valuable tool for detecting poor quality cucumbers before processing, and could allow the mechanical selection of high quality fruit on a large scale basis.

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Pick, Uri. « DUNALIELLA—A MODEL EXTREMOPHILIC ALGA ». Israel Journal of Plant Sciences 46, n^o 2 (13 mai 1998) : 131–39. http://dx.doi.org/10.1080/07929978.1998.10676720.

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The unicellular alga Dunaliella is unique in its ability to adapt to extreme environmental conditions. Adaptation to extreme salinity involves short-term and long-term responses. The former include osmotic adjustment by accumulation of large amounts of intracellular glycerol and efficient elimination of Na+ ions by plasma membrane transporters. The latter involves synthesis of two extrinsic plasma membrane proteins: a carbonic anhydrase and a novel type of a transferrin-like protein. These proteins are associated with acquisition of CO2 and Fe, respectively, whose availability is diminished in high salinity, limiting algal growth. Both proteins are functional over a wide range of salt concentrations and differ in structure from their mesophilic counterparts in possessing additional internal repeats and in having higher ratios of acidic: basic amino acids. Dunaliella acidophila survives at pH 0–1 by overexpression of a potent plasma membrane H+-ATPase which provides effective capacity for elimination of protons. Sequence comparisons of the ATPase genes from halophilic and acidophilic species reveals variations in charged amino acid composition within a distinct extrinsic C-terminal domain of the protein. Dunaliella bardawil adapts to high light intensity by several strategies: it accumulates large amounts of β-carotene which screens the photosynthetic system against photoinhibition and it modifies the photosynthetic machinery by synthesis of a special light-harvesting protein which presumably functions in dissipation of excessive light energy. Both responses depend on synthesis of special proteins and enzymes. Signal transduction mechanisms mediating stress responses in Dunaliella are poorly understood. Sensing osmotic/salinity changes involves specific plasma membrane sterols and activation of a plasma membrane protein kinase. Induction of β-carotene accumulation can be mimicked by reactive oxygen species generators.

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Shu, Chih-Wen, Youn-Shen Bee, Jiunn-Liang Chen, Chui-Lien Tsen, Wei-Lun Tsai et Shwu-Jiuan Sheu. « Detection of Autophagy-Related Gene Expression by Conjunctival Impression Cytology in Age-Related Macular Degeneration ». Diagnostics 11, n^o 2 (12 février 2021) : 296. http://dx.doi.org/10.3390/diagnostics11020296.

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Purpose: To investigate the association of autophagy-related gene expression with age-related macular degeneration (AMD). Methods: Patients with AMD were recruited for analysis by conjunctival impression cytology. mRNA was assessed by real-time polymerase chain reaction (RT-PCR) to evaluate whether the expression of 26 autophagy-related genes (ATGs) was correlated with AMD. Further studies on cell viability and autophagic flux in response to oxidative stress by H2O2 were performed in human retinal pigment epithelial (RPE) cell lines based on the results of impression cytology. Results: Both the neovascular AMD (nAMD) and polypoidal choroidal vasculopathy (PCV) groups had significantly higher mRNA levels of gamma-aminobutyric acid receptor-associated protein-like 1 (GABARAPL1) and microtubule-associated proteins 1A/1B light chain 3B (MAP1LC3B) than the control group, but there was no significant difference between these two groups. Age difference existed only in the AMD group. GABARAPL1 and MAP1LC3B mRNA expression increased significantly after acute oxidative stress in adult retinal pigment epithelial (ARPE-19) cells. Cell viability significantly increased and decreased in the cells harboring GABARAPL1 expression vector and silenced with siRNA against GABARAPL1, respectively, during short-term oxidative stress, whereas viability increased in the GABARAPL1-silenced cells after long-term oxidative stress. Silencing GABARAPL1 itself caused a reduction in autophagic flux under both short and long-term oxidative stress. Conclusion: Our study showed the possibility of assessing autophagy-related gene expression by conjunctival impression cytology. GABARAPL1 was significantly higher in AMD. Although an in vitro study showed an initial protective effect of autophagy, a cell viability study revealed the possibility of a harmful effect after long-term oxidative injury. The underlying mechanism or critical factors require further investigation.

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Salahuddin, Mohammed F., Fakhri Mahdi et Jason J. Paris. « HIV-1 Tat Dysregulates the Hypothalamic-Pituitary-Adrenal Stress Axis and Potentiates Oxycodone-Mediated Psychomotor and Anxiety-Like Behavior of Male Mice ». International Journal of Molecular Sciences 21, n^o 21 (3 novembre 2020) : 8212. http://dx.doi.org/10.3390/ijms21218212.

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Human immunodeficiency virus (HIV) is associated with co-morbid affective and stress-sensitive neuropsychiatric disorders that may be related to dysfunction of the hypothalamic-pituitary-adrenal (HPA) stress axis. The HPA axis is perturbed in up to 46% of HIV patients, but the mechanisms are not known. The neurotoxic HIV-1 regulatory protein, trans-activator of transcription (Tat), may contribute. We hypothesized that HPA dysregulation may contribute to Tat-mediated interactions with oxycodone, a clinically-used opioid often prescribed to HIV patients. In transgenic male mice, Tat expression produced significantly higher basal corticosterone levels with adrenal insufficiency in response to a natural stressor or pharmacological blockade of HPA feedback, recapitulating the clinical phenotype. On acute exposure, HIV-1 Tat interacted with oxycodone to potentiate psychomotor and anxiety like-behavior in an open field and light-dark transition tasks, whereas repeated exposure sensitized stress-related psychomotor behavior and the HPA stress response. Pharmacological blockade of glucocorticoid receptors (GR) partially-restored the stress response and decreased oxycodone-mediated psychomotor behavior in Tat-expressing mice, implicating GR in these effects. Blocking corticotrophin-releasing factor (CRF) receptors reduced anxiety-like behavior in mice that were exposed to oxycodone. Together, these effects support the notion that Tat exposure can dysregulate the HPA axis, potentially raising vulnerability to stress-related substance use and affective disorders.

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Yue, Jiammin, Dawei Shi, Liang Zhang, Zihan Zhang, Zhiyuan Fu, Qiong Ren et Jinchi Zhang. « The photo-inhibition of camphor leaves (Cinnamomum camphora L.) by NaCl stress based on physiological, chloroplast structure and comparative proteomic analysis ». PeerJ 8 (7 août 2020) : e9443. http://dx.doi.org/10.7717/peerj.9443.

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Background The distribution and use of camphor (Cinnamomum camphora L.) trees are constrained by increasing soil salinity in south-eastern China along the Yangtze River. However, the response mechanism of this species to salinity, especially in team of photosynthesis, are unknown. Methods Here, we analysed themorphological, physiological, ultrastructural, and proteomic traits of camphor seedlings under NaCl (103.45 mM) treatment in pot experiments for 80 days. Results The growth was limited because of photosynthetic inhibition, with the most significant disturbance occurring within 50 days. Salinity caused severe reductions in the leaf photosynthetic rate (An), stomatal conductance (gs), maximal chlorophyll fluorescence (Fm), maximum quantum yield of PSII (Fv/Fm), non-photochemical quenching (NPQ), relative quantum efficiency of PSII photochemistry (ΦPSII), photochemical quenching coefficient (qP) and photo-pigment contents (chlorophyll a (Cha), chlorophyll b (Chb), total chlorophyll (Chl)); weakened the antioxidant effects, including those of malondialdehyde (MDA), superoxide dismutase (SOD) and peroxidase (POD); and injured chloroplasts. The physiologicalresults indicated that the main reason for photo-inhibition was oxidative factors induced by NaCl. The proteomic results based on isobaric tags for relative and absolute quantitation (iTRAQ) further confirmedthat photosynthesis was the most significant disrupted process by salinity (P < 0.01) and there were 30 downregulated differentially expression proteins (DEPs) and one upregulated DEP related to restraint of the photosynthetic system, which affected photosystem I, photosystem II, the Cytochrome b6/f complex, ATP synthase and the light-harvesting chlorophyll protein complex. In addition, 57 DEPs were related to photo-inhibition by redox effect and 6 downregulated DEPs, including O2 evolving complex 33kD family protein (gi—224094610) and five other predicted proteins (gi—743921083, gi—743840443, gi—743885735, gi—743810316 and gi—743881832) were directly affected. This study provides new proteomic information and explains the possible mechanisms of photo-inhibition caused by salinity on C. camphor.

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Yudina, Lyubov, Ekaterina Sukhova, Maxim Mudrilov, Vladimir Nerush, Anna Pecherina, Alexandr A. Smirnov, Alexey S. Dorokhov, Narek O. Chilingaryan, Vladimir Vodeneev et Vladimir Sukhov. « Ratio of Intensities of Blue and Red Light at Cultivation Influences Photosynthetic Light Reactions, Respiration, Growth, and Reflectance Indices in Lettuce ». Biology 11, n^o 1 (1 janvier 2022) : 60. http://dx.doi.org/10.3390/biology11010060.

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LED illumination can have a narrow spectral band; its intensity and time regime are regulated within a wide range. These characteristics are the potential basis for the use of a combination of LEDs for plant cultivation because light is the energy source that is used by plants as well as the regulator of photosynthesis, and the regulator of other physiological processes (e.g., plant development), and can cause plant damage under certain stress conditions. As a result, analyzing the influence of light spectra on physiological and growth characteristics during cultivation of different plant species is an important problem. In the present work, we investigated the influence of two variants of LED illumination (red light at an increased intensity, the “red” variant, and blue light at an increased intensity, the “blue” variant) on the parameters of photosynthetic dark and light reactions, respiration rate, leaf reflectance indices, and biomass, among other factors in lettuce (Lactuca sativa L.). The same light intensity (about 180 µmol m−2s−1) was used in both variants. It was shown that the blue illumination variant increased the dark respiration rate (35–130%) and cyclic electron flow around photosystem I (18–26% at the maximal intensity of the actinic light) in comparison to the red variant; the effects were dependent on the duration of cultivation. In contrast, the blue variant decreased the rate of the photosynthetic linear electron flow (13–26%) and various plant growth parameters, such as final biomass (about 40%). Some reflectance indices (e.g., the Zarco-Tejada and Miller Index, an index that is related to the core sizes and light-harvesting complex of photosystem I), were also strongly dependent on the illumination variant. Thus, our results show that the red illumination variant contributes a great deal to lettuce growth; in contrast, the blue variant contributes to stress changes, including the activation of cyclic electron flow around photosystem I.

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Do, Nhung Quynh, Shengdao Zheng, Bom Park, Quynh T. N. Nguyen, Bo-Ram Choi, Minzhe Fang, Minseon Kim et al. « Camu-Camu Fruit Extract Inhibits Oxidative Stress and Inflammatory Responses by Regulating NFAT and Nrf2 Signaling Pathways in High Glucose-Induced Human Keratinocytes ». Molecules 26, n^o 11 (26 mai 2021) : 3174. http://dx.doi.org/10.3390/molecules26113174.

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Myrciaria dubia (HBK) McVaugh (camu-camu) belongs to the family Myrtaceae. Although camu-camu has received a great deal of attention for its potential pharmacological activities, there is little information on the anti-oxidative stress and anti-inflammatory effects of camu-camu fruit in skin diseases. In the present study, we investigated the preventative effect of 70% ethanol camu-camu fruit extract against high glucose-induced human keratinocytes. High glucose-induced overproduction of reactive oxygen species (ROS) was inhibited by camu-camu fruit treatment. In response to ROS reduction, camu-camu fruit modulated the mitogen-activated protein kinases (MAPK)/activator protein-1 (AP-1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and nuclear factor of activated T cells (NFAT) signaling pathways related to inflammation by downregulating the expression of proinflammatory cytokines and chemokines. Furthermore, camu-camu fruit treatment activated the expression of nuclear factor E2-related factor 2 (Nrf2) and subsequently increased the NAD(P)H:quinone oxidoreductase1 (NQO1) expression to protect keratinocytes against high-glucose-induced oxidative stress. These results indicate that camu-camu fruit is a promising material for preventing oxidative stress and skin inflammation induced by high glucose level.

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Crouzier, Lucie, Morgane Denus, Elodie M. Richard, Amarande Tavernier, Camille Diez, Nicolas Cubedo, Tangui Maurice et Benjamin Delprat. « Sigma-1 Receptor Is Critical for Mitochondrial Activity and Unfolded Protein Response in Larval Zebrafish ». International Journal of Molecular Sciences 22, n^o 20 (13 octobre 2021) : 11049. http://dx.doi.org/10.3390/ijms222011049.

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The sigma-1 receptor (S1R) is a highly conserved transmembrane protein highly enriched in mitochondria-associated endoplasmic reticulum (ER) membranes, where it interacts with several partners involved in ER-mitochondria Ca2+ transfer, activation of the ER stress pathways, and mitochondria function. We characterized a new S1R deficient zebrafish line and analyzed the impact of S1R deficiency on visual, auditory and locomotor functions. The s1r+25/+25 mutant line showed impairments in visual and locomotor functions compared to s1rWT. The locomotion of the s1r+25/+25 larvae, at 5 days post fertilization, was increased in the light and dark phases of the visual motor response. No deficit was observed in acoustic startle response. A critical role of S1R was shown in ER stress pathways and mitochondrial activity. Using qPCR to analyze the unfolded protein response genes, we observed that loss of S1R led to decreased levels of IRE1 and PERK-related effectors and increased over-expression of most of the effectors after a tunicamycin challenge. Finally, S1R deficiency led to alterations in mitochondria bioenergetics with decreased in basal, ATP-linked and non-mitochondrial respiration and following tunicamycin challenge. In conclusion, this new zebrafish model confirmed the importance of S1R activity on ER-mitochondria communication. It will be a useful tool to further analyze the physiopathological roles of S1R.

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Crouzier, Lucie, Morgane Denus, Elodie M. Richard, Amarande Tavernier, Camille Diez, Nicolas Cubedo, Tangui Maurice et Benjamin Delprat. « Sigma-1 Receptor Is Critical for Mitochondrial Activity and Unfolded Protein Response in Larval Zebrafish ». International Journal of Molecular Sciences 22, n^o 20 (13 octobre 2021) : 11049. http://dx.doi.org/10.3390/ijms222011049.

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The sigma-1 receptor (S1R) is a highly conserved transmembrane protein highly enriched in mitochondria-associated endoplasmic reticulum (ER) membranes, where it interacts with several partners involved in ER-mitochondria Ca2+ transfer, activation of the ER stress pathways, and mitochondria function. We characterized a new S1R deficient zebrafish line and analyzed the impact of S1R deficiency on visual, auditory and locomotor functions. The s1r+25/+25 mutant line showed impairments in visual and locomotor functions compared to s1rWT. The locomotion of the s1r+25/+25 larvae, at 5 days post fertilization, was increased in the light and dark phases of the visual motor response. No deficit was observed in acoustic startle response. A critical role of S1R was shown in ER stress pathways and mitochondrial activity. Using qPCR to analyze the unfolded protein response genes, we observed that loss of S1R led to decreased levels of IRE1 and PERK-related effectors and increased over-expression of most of the effectors after a tunicamycin challenge. Finally, S1R deficiency led to alterations in mitochondria bioenergetics with decreased in basal, ATP-linked and non-mitochondrial respiration and following tunicamycin challenge. In conclusion, this new zebrafish model confirmed the importance of S1R activity on ER-mitochondria communication. It will be a useful tool to further analyze the physiopathological roles of S1R.

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