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BACKGROUND: Rice (Oryza sativa L.) is one of the most important food crops in the world and the application of nitrogen fertilizer is an effective means of ensuring stable and high rice yields. However, excessive application of nitrogen fertilizer not only causes a decline in the quality of rice, but also leads to a series of environmental costs. Nitrogen reutilization is closely related to leaf senescence, and nitrogen deficiency will lead to early functional leaf senescence, whereas moderate nitrogen application will help to delay leaf senescence and promote the production of photosynthetic assimilation products in leaves to achieve yield increase. Therefore, it is important to explore the mechanism by which nitrogen affects rice senescence, to search for genes that are tolerant to low nitrogen, and to delay the premature senescence of rice functional leaves. RESULTS: The present study was investigated the transcriptional changes in flag leaves between full heading and mature grain stages of rice (O. sativa) sp. japonica 'NanGeng 5718' under varying nitrogen (N) application: 0 kg/ha (no nitrogen; 0N), 240 kg/ha (moderate nitrogen; MN), and 300 kg/ha (high nitrogen; HN). Compared to MN condition, a total of 10427 and 8177 differentially expressed genes (DEGs) were detected in 0N and HN, respectively. We selected DEGs with opposite expression trends under 0N and HN conditions for GO and KEGG analyses to reveal the molecular mechanisms of nitrogen response involving DEGs. We confirmed that different N applications caused reprogramming of plant hormone signal transduction, glycolysis/gluconeogenesis, ascorbate and aldarate metabolism and photosynthesis pathways in regulating leaf senescence. Most DEGs of the jasmonic acid, ethylene, abscisic acid and salicylic acid metabolic pathways were up-regulated under 0N condition, whereas DEGs related to cytokinin and ascorbate metabolic pathways were induced in HN. Major transcription factors include ERF, WRKY, NAC and bZIP TF families have similar expression patterns which were induced under N starvation condition. CONCLUSION: Our results revealed that different nitrogen levels regulate rice leaf senescence mainly by affecting hormone levels and ascorbic acid biosynthesis. Jasmonic acid, ethylene, abscisic acid and salicylic acid promote early leaf senescence under low nitrogen condition, ethylene and ascorbate delay senescence under high nitrogen condition. In addition, ERF, WRKY, NAC and bZIP TF families promote early leaf senescence. The relevant genes can be used as candidate genes for the regulation of senescence. The results will provide gene reference for further genomic studies and new insights into the gene functions, pathways and transcription factors of N level regulates leaf senescence in rice, thereby improving NUE and reducing the adverse effects of over-application of N.
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Perfilação da Expressão Gênica , Nitrogênio , Oryza , Folhas de Planta , Fatores de Transcrição , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Oryza/fisiologia , Nitrogênio/metabolismo , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Senescência Vegetal/genética , Regulação da Expressão Gênica de Plantas , Vias Biossintéticas/genética , Transcriptoma , Fertilizantes , Genes de PlantasRESUMO
A terahertz photonic crystal fiber with two sensing channels was designed. Graphene coated on the micro-grooves in the cladding was used as plasma material to introduce tunability. The dispersion relation, mode coupling, and sensing characteristics of the fiber were studied using the finite element method. Ultrahigh sensitivity of 2.014 THz/RIU and 0.734 GHz/°C were obtained for analytes with refractive index in the range of 1.33 to 1.4 and environment temperature in the range of 10-60 °C, respectively. Refractive index resolution can reach the order of 10-5. The dual parameter simultaneous detection, dynamic tunable characteristics, and working in the low-frequency range of terahertz enable the designed photonic crystal fiber to have application prospects in the field of biosensing.
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Rare earth elements (REEs) are emerging as an anticipated pollution in the environment due to their active use in many areas. However, the effects of REEs on the photosynthesis of rice have not been thoroughly explored. Therefore, this study emphasizes how high levels of La(III) affect the thylakoid membrane of rice seedlings, thereby inhibiting photosynthesis and growth. Here, we reported that rice plants treated with La(III) exhibited an increase in La accumulation in the leaves, accompanied by a decrease in chlorophyll content and photosynthetic capacity. La(III) exposure decreased Mg content in leaves, but possibly increased other nutrients including Cu, Mn, and Zn through systemic endocytosis. K-band and L-band appeared in the fluorescence OJIP transients, indicating La(III) stress destroyed the donor and receptor sides of photosystem II (PSII). Numerous reaction centers (RC/CSm) were inactivated by La(III) treatment, which resulted in a reduction in electron transport capacity (decreased ETo/RC and ETo/CSm) and an increase in the dissipation of the excess excitation energy by heat (increased DIo/RC and DIo/CSm). The BN-PAGE analysis of thylakoid membrane protein complexes showed that La(III) induced the degradation of supercomplexes, PSII core, LHCII, PSI core, LHCI, and F1-ATPase binding Cyt b6f complex. Collectively, this study revealed that La(III) causes significant degradation of thylakoid membrane proteins, thereby promoting the decomposition of photosynthetic complexes, ultimately destroying the chloroplast structure and reducing the photosynthetic performance of rice seedlings.
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Oryza , Tilacoides , Proteínas de Membrana , Lantânio/toxicidade , Plântula , Fluorescência , Cloroplastos , Fotossíntese , Proteínas das Membranas dos Tilacoides , ClorofilaRESUMO
The root-apex transition zone (TZ), the major perception site for aluminium (Al) toxicity, is crucial for the Al-induced root-growth inhibition, while the mechanism underlying silicon-mediated alleviation of Al toxicity in the TZ is largely unknown. In this study, the role of silicon (Si) in alleviating Al-induced damage in the TZ and root-growth inhibition of rice was investigated. We found that Si had direct alleviative effect on Al toxicity as revealed by less root growth-inhibition, Al accumulation, and callose formation. Si reversed Al-induced decreases of the cell wall elongation and extensibility, and reduced Al-induced increments of cell wall polysaccharides in the TZ. The similar distribution patterns of Al and Si in the cell wall indicated that Si might detoxify Al by forming hydroxyaluminumsilicates in the apoplast of the root-apex TZ. Moreover, the wall-bound form of Si reduced Al binding sites, thereby reducing the capability of Al bound to the cell wall. These results suggest that Si-mediated cell wall modification in the TZ alleviates Al-induced root-growth inhibition in rice involving the promotion of cell wall extensibility and the decrease of Al accumulation in the cell wall.
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Oryza , Alumínio/farmacologia , Parede Celular/metabolismo , Oryza/metabolismo , Raízes de Plantas/metabolismo , Silício/metabolismo , Silício/farmacologiaRESUMO
In this paper, nanostructured Molybdenum Selenide (MoSe2) with composited phases are synthesized by hydrothermal method, and the products are modified by metal anoparticles to improve the gas sensing performance. Microstructure characterization shows that few layered 1T/2H-MoSe2 nanosheets have been successfully prepared. Both the morphology and composition of nanosheets could be tuned by the reaction parameters. It is shown the MoSe2-based nanomaterials have excellent selectivity to Nitrogen dioxide (NO2) according to gas sensing properties measurement. The sensitivity of 1T/2H-MoSe2 nanosheets modified by Cu nanoparticles is 17.73 (50 ppm NO2) at the optimal operating temperature, which is the highest compared with other samples. The sensors also exhibit rapid response/recovery time and high stability. The sensing mechanism of MoSe2 nanosheets toward NO2 is investigated based on the first-principles calculation. The results suggest the modification by metal nanoparticles could significantly improve the adsorption energy and the charge transfer between gas molecule and MoSe2. This work demonstrates a promising guidance for the design of new NO2 gas sensing materials and devices.
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In this paper, nanostructured molybdenum selenide (MoSe2) with composited phases are synthesized by hydrothermal method, and the products are modified by metal anoparticles to improve the gas sensing performance. Microstructure characterization shows that few layered 1T/2H-MoSe2nanosheets have been successfully prepared. Both the morphology and component of nanosheets could be tuned by the reaction parameters. It is shown the MoSe2-based nanomaterials have excellent selectivity to nitrogen dioxide (NO2) according to gas sensing properties measurement. The sensitivity of 1T/2H-MoSe2nanosheets modified by Cu nanoparticles is 17.73 (50 ppm NO2) at the optimal operating temperature, which is the highest compared with other samples. The sensors also exhibit rapid response/recovery time and high stability. The sensing mechanism of MoSe2nanosheets toward NO2is investigated based on the first-principles calculation. The results suggest the modification by metal nanoparticles could significantly improve the adsorption energy and charge transfer between gas molecule and MoSe2. This work demonstrates a promising guidance for the design of new NO2gas sensing materials and devices.
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Aluminum (Al) toxicity is a major yield-limiting factor for crops in acidic soils. In this work, we have investigated the potential role of spermidine (Spd) on Al toxicity in rice chloroplasts. Exogenous Spd markedly reduced Al concentration and elevated other nutrient elements such as Mn, Mg, Fe, K, Ca, and Mo in chloroplasts of Al-treated plants. Meanwhile, Spd further activated arginine decarboxylase (ADC) activity of key enzyme in polyamine (PA) synthesis, and enhanced PA contents in chloroplasts. Spd application dramatically addressed Al-induced chlorophyll (Chl) losses, inhibited thylakoid membrane protein complexes degradation, especially photosystem II (PSII), and significantly depressed the accumulations of superoxide radical (O2·-), hydrogen peroxide (H2O2), and malondialdehyde (MDA) in chloroplasts. Spd addition activated antioxidant enzyme activities and decreased soluble sugar content in chloroplasts compared with Al treatment alone. Spd not only reversed the inhibition of photosynthesis-related gene transcript levels induced by Al toxicity, but diminished the increased expression of Chl catabolism-related genes. Furthermore, Chl fluorescence analysis showed that Spd protected PSII reaction centers and photosynthetic electron transport chain under Al stress, thus improving photosynthetic performance. These results suggest that PAs are involved in Al tolerance in rice chloroplasts and can effectively protect the integrity and function of photosynthetic apparatus, especially PSII, by mitigating oxidative damage induced by Al toxicity.
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Alumínio/toxicidade , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Espermidina/farmacologia , Alumínio/metabolismo , Antioxidantes/metabolismo , Clorofila/metabolismo , Cloroplastos/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/metabolismo , Poliaminas/metabolismo , Espermidina/metabolismoRESUMO
Introduction of C4 photosynthetic traits into C3 crops is an important strategy for improving photosynthetic capacity and productivity. Here, we report the research results of a variant line of sorghum-rice (SR) plant with big panicle and high spikelet density by introducing sorghum genome DNA into rice by spike-stalk injection. The whole-genome resequencing showed that a few sorghum genes could be integrated into the rice genome. Gene expression was confirmed for two C4 photosynthetic enzymes containing pyruvate, orthophosphate dikinase and phosphoenolpyruvate carboxykinase. Exogenous sorghum DNA integration induced a series of key traits associated with the C4 pathway called "proto-Kranz" anatomy, including leaf thickness, bundle sheath number and size, and chloroplast size in bundle sheath cells. Significantly, transgenic plants exhibited enhanced photosynthetic capacity resulting from both photosynthetic CO2-concentrating effect and improved energy balance, which led to an increase in carbohydrate levels and productivity. Furthermore, such rice plant exhibited delayed leaf senescence. In summary, this study provides a proof for the feasibility of inducing the transition from C3 leaf anatomy to proto-Kranz by spike-stalk injection to achieve efficient photosynthesis and increase productivity.
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Oryza/fisiologia , Fotossíntese , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Sorghum/fisiologia , Dióxido de Carbono/metabolismo , Genoma de Planta , Oryza/anatomia & histologia , Oryza/genética , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/anatomia & histologia , Plantas Geneticamente Modificadas/genética , Sorghum/anatomia & histologia , Sorghum/genéticaRESUMO
In C4 plants, the vascularization of the leaf is extended to include a ring of photosynthetic bundle sheath cells, which have essential and specific functions. In contrast to the substantial knowledge of photosynthesis in C4 plants, relatively little is known about photosynthesis in C3 plant veins, which differs substantially from that in C3 mesophyll cells. In this review we highlight the specific photosynthetic machinery present in C3 vascular cells, which likely evolved prior to the divergence between C3 and C4 plants. The associated primary processes of carbon recapture, nitrogen transport, and antioxidant metabolism are discussed. This review of the basal C4 photosynthesis in C3 plants is significant in the context of promoting the potential for biotechnological development of C4-transgenic rice crops.
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Carbono/metabolismo , Nitrogênio/metabolismo , Oryza/fisiologia , Fotossíntese , Antioxidantes/metabolismo , Transporte Biológico , Vias Biossintéticas , Ciclo do Carbono , Células do Mesofilo/fisiologia , Modelos Biológicos , Oryza/crescimento & desenvolvimento , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Feixe Vascular de Plantas/crescimento & desenvolvimento , Feixe Vascular de Plantas/fisiologia , Transdução de SinaisRESUMO
Individual nanoparticles embedded in molecularly thin films at planar substrates and the resulting film surface distortion (meniscus) adjacent to the nanoparticles are investigated by conventional optical reflection microscopy. Even for nanoparticles much smaller than the Rayleigh diffraction limit, the meniscus creates such a pronounced optical footprint that the location of the nanoparticles can be identified. This is because the decay length (lateral extension) of the meniscus exceeds the size of the nanoparticle by orders of magnitude. Therefore, for the first time, the exact shape of the meniscus of the liquid adjacent to a nanosize object could be measured and analyzed. The meniscus has a zero curvature shape (cosine hyperbolic). The liquid in the meniscus is in pressure equilibrium with the far-field planar film. The decay length decreases with the decreasing nanoparticle size. However, it is independent of the far-field film thickness. Supposedly, the decay length is determined by van der Waals interactions although it is unknown what determines its (unexpectedly large) absolute value. The presented technical approach may be used to investigate biological systems (for instance, surface distortions in supported membranes caused by proteins or protein aggregates).
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Chlorophyll a fluorescence of flag leaves in a super-high-yielding hybrid rice (Oryza sativa L.) LYPJ, and a traditional hybrid rice SY63 cultivar with lower grain yield, which were grown in the field, were investigated from emergence through senescence of flag leaves. As the flag leaf matured, there was an increasing trend in photosynthetic parameters such as quantum efficiency of primary photochemistry ([Formula: see text] Po) and efficiency of electron transport from PS II to PS I (Ψ Eo). The overall photosynthetic performance index (PIABS) was significantly higher in the high-yielding LYPJ compared to SY63 during the entire reproductive stage of the plant, the same to MDA content. However, [Formula: see text] Po(=F V/F M), an indicator of the primary photochemistry of the flag leaf, did not display significant changes with leaf age and was not significantly different between the two cultivars, suggesting that PIABS is a more sensitive parameter than [Formula: see text] Po (=F V/F M) during leaf age for distinguishing between cultivars differing in yield.
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Clorofila/metabolismo , Oryza/fisiologia , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/fisiologia , Biomassa , Quimera , Clorofila A , Transporte de Elétrons , Fluorescência , Oryza/efeitos da radiação , Fotoquímica , Folhas de Planta/efeitos da radiaçãoRESUMO
In the present study, photosynthetic responses induced by cadmium stress in chlorophyll biosynthesis, photochemical activities, the stability of thylakoid membranes chlorophyll-protein complexes and the chloroplast ultrastructure of the cereal crop Oryza sativa L. were characterized. Cadmium inhibited the biosynthesis of chlorophyll by interfering with activity of δ-aminolevulinic acid dehydratase in the rice seedlings. For the photochemical activities analyses, the extent of the decrease in photosystem II activity was much greater than that in the PS I activity. The variations in the chlorophyll a fluorescence parameters also indicated that cadmium toxicity drastically affected the photochemistry of PS II. Biochemical analyses by BN-PAGE and protein immunoblot showed that cadmium toxicity considerably affected the stability of PS II-core, cytb 6 /f, RuBisCO, PSI + LHCI and LHCII (Trimeric). We observed the rate of the thylakoid membranes protein degradation, was mainly at the level of RbcL, PsaA, Lhca1 and D1. In addition, the damages to chloroplast structure and thylakoid stacking analyzed by transmission electron microscopy were indicative of general disarray in the photosynthetic functions exerted by cadmium toxicity. These results are valuable for understanding the biological consequences of heavy metals contamination particularly in soils devoted to organic agriculture.
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Cádmio/farmacologia , Cloroplastos/ultraestrutura , Oryza/efeitos dos fármacos , Oryza/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Plântula/efeitos dos fármacos , Clorofila/biossíntese , Cloroplastos/efeitos dos fármacos , Oryza/citologia , Oryza/ultraestrutura , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Plântula/citologia , Plântula/metabolismoRESUMO
The volatile organic compounds (VOCs) of plant hosts allow insect localization through olfactory recognition. In this study, the oviposition behavior of the codling moth was investigated and the VOCs from different walnut organs were extracted and analyzed to systematically study their composition and content differences. The electrophysiological and behavioral responses of the codling moth to walnut VOCs were measured using gas chromatography-electroantennographic detection (GC-EAD) and a four-arm olfactometer to screen the key active contents. The field investigation results indicated that 90.3% of the eggs spawned by the first generation of adult codling moths were adjacent to the walnut fruits. Walnut VOCs are mainly composed of terpenes, aromatics, and alkanes. Twelve VOCs can produce electroantennogenic (EAG) responses in the codling moths. Both adult males and females exhibit concentration dependence, with notable disparities in their EAG response levels. In the olfactory behavioral bioassay, linalool, eucalyptol, and high doses of geranyl acetate showed repellent effects on the codling moths, while myrcene, ß-ocimene, nonanal, methyl salicylate, α-farnesene, and heptaldehyde showed the opposite. The relative levels of heptaldehyde, geranyl acetate, nonanal, and methyl salicylate were high in the fruits, which is intimately related to the localization of the walnut fruit by females. These VOCs can influence the oviposition behavior of codling moths but their application in the control of this pest needs to be confirmed and improved through further field experiments.
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CONTEXT: The electronic and magnetic properties of non-metallic (NM) elements doping defective graphene-like ZnO (g-ZnO) monolayer including O vacancy (VO) and Zn vacancy (VZn) are studied. The results show that VO-g-ZnO is a semiconductor and VZn-g-ZnO is a magnetic semiconductor. B, C, N, Si, P, 2S, and 2Si doping VO-g-ZnO systems present half-metal and magnetic semiconductors, and the magnetism mainly originates from the spin polarization of doping atoms. For single or double NM elements doping VZn-g-ZnO, 2P doping system presents a semiconductor, while other systems present ferromagnetic metal, half-metal, and magnetic semiconductor. The magnetism of single NM elements doping VZn-g-ZnO mainly comes from the spin polarization of O atoms near the defect point. For double NM elements doping VZn-g-ZnO, spin splitting occurs mainly in p orbitals of O atoms, dopant atoms, and d orbitals of Zn atoms. NM elements doping defect g-ZnO can effectively regulate the electronic and magnetic properties of the system. METHODS: The software package VASP 5.4.1 (Vienna ab initio Simulation Package) is used for calculations in this paper. The local density approximation (LDA) is adopted as an exchange and correlation function to perform the structural optimization and analysis of electronic structure and magnetic properties.
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Climate change is one of the main challenges, and it poses a tough challenge to the agriculture industry globally. Additionally, greenhouse gas (GHG) emissions are the main contributor to climate change; however, croplands are a prominent source of GHG emissions. Yet this complex challenge can be mitigated through climate-smart agricultural practices. Conservation tillage is commonly known to preserve soil and mitigate environmental change by reducing GHG emissions. Nonetheless, there is still a paucity of information on the influences of conservation tillage on wheat yield, soil properties, and GHG flux, particularly in the semi-arid Dingxi belt. Hence, in order to fill this gap, different tillage systems, namely conventional tillage (CT) control, straw incorporation with conventional tillage (CTS), no-tillage (NT), and stubble return with no-tillage (NTS), were laid at Dingxi, Gansu province of China, under a randomized complete block design with three replications to examine their impacts on yield, soil properties, and GHG fluxes. Results depicted that different conservative tillage systems (CTS, NTS, and NT) significantly (p < 0.05) increased the plant height, number of spikes per plant, seed number per meter square, root yield, aboveground biomass yield, thousand-grain weight, grain yield, and dry matter yield compared with CT. Moreover, these conservation tillage systems notably improved the soil properties (soil gravimetric water content, water-filled pore space, water storage, porosity, aggregates, saturated hydraulic conductivity, organic carbon, light fraction organic carbon, carbon storage, microbial biomass carbon, total nitrogen, available nitrogen storage, microbial biomass nitrogen, total phosphorous, available phosphorous, total potassium, available potassium, microbial counts, urease, alkaline phosphatase, invertase, cellulase, and catalase) while decreasing the soil temperature and bulk density over CT. However, CTS, NTS, and NT had non-significant effects on ECe, pH, and stoichiometric properties (C:N ratio, C:P ratio, and N:P ratio). Additionally, conservation-based tillage regimes NTS, NT, and CTS significantly (p < 0.05) reduced the emission and net global warming potential of greenhouse gases (carbon dioxide, methane, and nitrous oxide) by 23.44, 19.57, and 16.54%, respectively, and decreased the greenhouse gas intensity by 23.20, 29.96, and 18.72%, respectively, over CT. We conclude that NTS is the best approach to increasing yield, soil and water conservation, resilience, and mitigation of agroecosystem capacity.
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AIM: Sesamin is one of the major lignans in sesame seeds with antihyperlipidemic, antioxidative and antihypertensive activities. The aim of this study was to examine the effects of sesamin on arterial function in spontaneously hypertensive rats (SHRs). METHODS: SHRs were orally administered sesamin (40, 80 and 160 mg·kg(-1)·d(-1)) for 16 weeks. After the rats were killed, thoracic aortas were dissected out. The vasorelaxation responses of aortic rings to ACh and nitroprusside were measured. The expression of eNOS and NADPH oxidase subunits p47(phox) and p22(phox) in aortas were detected using Western blotting and immunohistochemistry. Aortic nitrotyrosine was measured with ELISA. The total antioxidant capacity (T-AOC) and MDA levels in aortas were also determined. RESULTS: The aortic rings of SHRs showed significantly smaller ACh-induced and nitroprusside-induced relaxation than those of control rats. Treatment of SHRs with sesamin increased both the endothelium-dependent and endothelium-independent relaxation of aortic rings in a dose-dependent manner. In aortas of SHRs, the level of T-AOC and the expression of nitrotyrosine, p22(phox) and p47(phox) proteins were markedly increased, while the level of MDA and the expression of eNOS protein were significantly decreased. Treatment of SHRs with sesamin dose-dependently reversed these biochemical and molecular abnormalities in aortas. CONCLUSION: Long-term treatment with sesamin improves arterial function in SHR through the upregulation of eNOS expression and downregulation of p22(phox) and p47(phox) expression.
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Aorta Torácica/fisiopatologia , Dioxóis/farmacologia , Regulação para Baixo/genética , Lignanas/farmacologia , NADPH Oxidases/antagonistas & inibidores , Óxido Nítrico Sintase Tipo III/biossíntese , Regulação para Cima/genética , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/enzimologia , Dioxóis/uso terapêutico , Regulação para Baixo/efeitos dos fármacos , Hipertensão/tratamento farmacológico , Hipertensão/enzimologia , Hipertensão/fisiopatologia , Lignanas/uso terapêutico , Masculino , NADPH Oxidases/biossíntese , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico Sintase Tipo III/fisiologia , Técnicas de Cultura de Órgãos , Subunidades Proteicas/antagonistas & inibidores , Subunidades Proteicas/biossíntese , Distribuição Aleatória , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Regulação para Cima/efeitos dos fármacosRESUMO
Atomically precise Au(n) nanoclusters (n = number of gold atom in cluster) ideally composed of an exact number of gold atoms have unique core-shell structure and non-metallic electronic properties. The extremely small size of Au25 and Au38 nanoclusters induces a large energy gap in their electronic structures, which gives rise to unprecedented catalytic activity in some chemical reactions. Here we report dehydration of phenylboronic acid to boroxine with small Au25 and Au38 nanocluster catalysts, respectively. Especially, Au25 nanocluster is arranged with Au13 icosahedral core capped by twelve gold atoms as an exterior shell. Au38 nanocluster is a face-fused biicosahedral Au23 core encapsulated by a shell comprised of fifteen gold atoms. Au38 nanoclusters exhibit higher activity than Au25 nanoclusters. This study is an attempt to provide a powerful tool for the catalyst design and to gain a further insight into the correlation of structural properties with catalytic properties.
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Boro/química , Ácidos Borônicos/química , Ouro/química , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Modelos Moleculares , Água/química , Catálise , Teste de Materiais , Modelos Químicos , Conformação MolecularRESUMO
The supply of silicon (Si) mitigates the aluminum (Al) toxicity on plant root growth, while the underlying mechanism remains unknown. Transition zone (TZ) emerges as the Al-toxicity target of plant root apex. The objective of the study was to evaluate the effect of Si on redox homeostasis in root-apex TZ of rice seedlings under Al stress. Si alleviated Al toxicity as revealed by promotion of root elongation and less Al accumulation. In Si-deprived plants, treatment with Al altered the normal distribution of superoxide anion (O2·-) and hydrogen peroxide (H2O2) in root tip. Al induced a significant increase of reactive oxygen species (ROS) in root-apex TZ, resulting in the peroxidation of membrane lipid and loss of plasma membrane integrity in root-apex TZ. However, Si greatly increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and enzymes involved in ascorbate-glutathione (AsA-GSH) cycle in root-apex TZ under Al stress, and enhanced AsA and GSH contents, which reduced ROS and callose contents, thereby reducing malondialdehyde (MDA) content and Evans blue uptake. These results allow to precise the changes of ROS in root-apex TZ after exposure to Al, and the positive role of Si in maintaining redox balance in root-apex TZ.
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Antioxidantes , Oryza , Alumínio/toxicidade , Antioxidantes/metabolismo , Homeostase , Peróxido de Hidrogênio/metabolismo , Oryza/metabolismo , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Silício/farmacologia , Silício/metabolismoRESUMO
In an in-depth investigation of membraneless hydrogen peroxide-based fuel cells (H2O2 FCs), hydrogen peroxide (H2O2), a carbon-neutral compound, is demonstrated to undergo electrochemical decomposition to produce H2O, O2, and electrical energy. The unique redox properties of H2O2 position it as a viable candidate for sustainable energy applications. The proposed membraneless design addresses the limitations of conventional fuel cells, including fabrication complexities and design challenges. A novel three-dimensional electrode, synthesized via electroplating techniques, is introduced. Constructed from Au-electroplated carbon fiber cloth combined with Ni-foam, this electrode showcases enhanced electrochemical reaction kinetics, leading to an increased power density for H2O2 FCs. The performance of fuel cells is intricately linked to the pH levels of the electrolyte solution. Beyond FC applications, such electrodes hold potential in portable energy systems and as high surface area catalysts. This study emphasizes the significance of electrode engineering in optimizing the potential of H2O2 as an environmentally friendly energy source.
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Eletricidade , Peróxido de Hidrogênio , Peróxido de Hidrogênio/química , Oxirredução , Eletrodos , Fibra de CarbonoRESUMO
The emergence of "nanomotors", "nanomachines", and "nanorobotics" has transformed dynamic nanoparticle research, driving a transition from passive to active and intelligent nanoscale systems. This review examines two critical fields: the investigation of airborne particles, significant contributors to air pollution, and the rapidly emerging domain of catalytic and field-controlled nano- and micromotors. We examine the basic concepts of nano- and micromachines in motion and envision their possible use in a gaseous medium to trap and neutralize hazardous particulates. While past studies described the application of nanotechnology and nanomotors in various scenarios, airborne nano/micromachine motion and their control have yet to be thoroughly explored. This review intends to promote multidisciplinary research on nanomachines' propulsion and task-oriented applications, highlighting their relevance in obtaining a cleaner atmospheric environment, a critical component to consider for human health.