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1.
Plant Physiol ; 182(1): 408-423, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31685645

RESUMO

Members of the mitochondrial transcription terminator factor (mTERF) family, originally identified in vertebrate mitochondria, are involved in the termination of organellular transcription. In plants, mTERF proteins are mainly localized in chloroplasts and mitochondria. In Arabidopsis (Arabidopsis thaliana), mTERF8/pTAC15 was identified in the plastid-encoded RNA polymerase (PEP) complex, the major RNA polymerase of chloroplasts. In this work, we demonstrate that mTERF8 is associated with the PEP complex. An mTERF8 knockout line displayed a wild-type-like phenotype under standard growth conditions, but showed impaired efficiency of photosystem II electron flow. Transcription of most chloroplast genes was not substantially affected in the mterf8 mutant; however, the level of the psbJ transcript from the psbEFLJ polycistron was increased. RNA blot analysis showed that a larger transcript accumulates in mterf8 than in the wild type. Thus, abnormal transcription and/or RNA processing occur for the psbEFLJ polycistron. Circular reverse transcription PCR and sequence analysis showed that the psbJ transcript terminates 95 nucleotides downstream of the translation stop codon in the wild type, whereas its termination is aberrant in mterf8 Both electrophoresis mobility shift assays and chloroplast chromatin immunoprecipitation analysis showed that mTERF8 specifically binds to the 3' terminal region of psbJ Transcription analysis using the in vitro T7 RNA polymerase system showed that mTERF8 terminates psbJ transcription. Together, these results suggest that mTERF8 is specifically involved in the transcription termination of the chloroplast gene psbJ.

2.
Polymers (Basel) ; 11(12)2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31835582

RESUMO

In this paper, the reaction characteristic of a novel reactive material, which introduced bismuth trioxide (Bi2O3) into traditional polytetrafluoroethylene/aluminum (PTFE/Al), is studied. The effect of Bi2O3 with different content and particle size on the reaction behaviors of PTFE/Al/Bi2O3 are investigated by drop-weight test and X-ray diffractometer (XRD), including impact sensitivity, energy release performance under a certain impact, and reaction mechanism. The experimental results show that the content of Bi2O3 increased from 0% to 35.616%, the characteristic drop height of impact sensitivity (H50) of PTFE/Al/Bi2O3 reactive materials decreased first and then increased, and the minimum H50 of all types of materials in the experiment is 0.74 times that of PTFE/Al, and the particle size of Bi2O3 affects the rate of H50 change with Bi2O3 content. Besides, with the increase of Bi2O3 content, both the reaction intensity and duration first increase and then decrease, and there is optimum content of Bi2O3 maximizing the reaction degree of the PTFE/Al/Bi2O3. Furthermore, a prediction model for the impact sensitivity of PTFE-based reactive material is developed. The main reaction products include AlF3, xBi2O3·Al2O3, and Bi.

3.
Materials (Basel) ; 12(21)2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31653065

RESUMO

The traditional polytetrafluoroethylene (PTFE)/Al reactive material liner shaped charge generally produces insufficient penetration depth, although it enlarges the penetration hole diameter by chemical energy release inside the penetration crater. As such, a novel high-density reactive material liner based on the PTFE matrix was fabricated, and the corresponding penetration performance was investigated. Firstly, the PTFE/W/Cu/Pb high-density reactive material liner was fabricated via a cold pressing/sintering process. Then, jet formation and penetration behaviors at different standoffs were studied by pulse X-ray and static experiments, respectively. The X-ray results showed that the PTFE/W/Cu/Pb high-density reactive material liner forms an excellent reactive jet penetrator, and the static experimental results demonstrated that the penetration depth of this high-density reactive jet increased firstly and then decreased by increasing the standoff. When the standoff was 1.5 CD (charge diameter), the penetration depth of this reactive jet reached 2.82 CD, which was significantly higher than that of the traditional PTFE/Al reactive jet. Moreover, compared with the conventional metal copper jet penetrating steel plates, the entrance hole diameter caused by this high-density reactive jet improved 29.2% at the same standoff. Lastly, the chemical reaction characteristics of PTFE/W/Cu/Pb reactive materials were analyzed, and a semi-empirical penetration model of the high-density reactive jet was established based on the quasi-steady ideal incompressible fluid dynamics theory.

4.
Materials (Basel) ; 12(17)2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31466348

RESUMO

The penetration enhancement behaviors of a reactive material double-layered liner (RM-DLL) shaped charge against thick steel targets are investigated. The RM-DLL comprises an inner copper liner, coupled with an outer PTFE (polytetrafluoroethylene)/Al reactive material liner, fabricated via a cold pressing/sintering process. This RM-DLL shaped charge presents a novel defeat mechanism that incorporates the penetration capability of a precursor copper jet and the chemical energy release of a follow-thru reactive material penetrator. Experimental results showed that, compared with the single reactive liner shaped charge jet, a deeper penetration depth was produced by the reactive material-copper jet, whereas the penetration performance and reactive material mass entering the penetrated target strongly depended on the reactive liner thickness and standoff. To further illustrate the penetration enhancement mechanism, numerical simulations based on AUTODYN-2D code were conducted. Numerical results indicated that, with increasing reactive liner thickness, the initiation delay time of the reactive materials increased significantly, which caused the penetration depth and the follow-thru reactive material mass to increase for a given standoff. This new RM-DLL shaped charge configuration provides an extremely efficient method to enhance the penetration damage to various potential targets, such as armored fighting vehicles, naval vessels, and concrete targets.

5.
J Nanosci Nanotechnol ; 19(12): 7729-7735, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31196282

RESUMO

Graphitic carbon nitride (g-C3N4) can be used as a photocatalytic initiator and stabilizer in the process of Pickering emulsion polymerization for polystyrene/g-C3N4. After carbonization, highly catalytically active carbon (C)/g-C3N4 is obtained. The properties of the photocatalysts are characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, and electrochemical analysis. The degradation of methylene blue is investigated to determine the activity of the photocatalyst. The results suggest that polystyrene nanospheres coated with g-C3N4 can be obtained when the volume ratio of the g-C3N4 aqueous dispersion and styrene is more than 40. The obtained polystyrene/g-C3N4 exhibits strong interaction of matter causing by Pickering emulsion polymerization using g-C3N4 as the photocatalytic initiators and stabilizer. The interaction still exists in C/g-C3N4 when the polystyrene is carbonized, which can enhance the separation efficiency of photoelectron-hole pairs, reduce the charge transfer resistance, and accelerate the degradation of methylene blue. It is worth noting that the photocurrent density of C/g-C3N4 is about 68.3 times that of the original g-C3N4.

6.
Plant J ; 98(6): 1078-1089, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30834637

RESUMO

Phosphoglycerate kinase (PGK) is a highly conserved reversible enzyme that participates in both glycolysis and photosynthesis. In Arabidopsis thaliana, one cytosolic PGK (PGKc) and two plastidial PGKs (PGKp) are known. It remains debatable whether the two PGKp isozymes are functionally redundant or specialized in plastidial carbon metabolism and fixation. Here, using a pooled clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) strategy, we found that plants with single mutations in pgkp1 or pgkp2 were not significantly affected, whereas a pgkp1pgkp2 double mutation was lethal due to retarded carbon fixation, suggesting that PGKp isozymes play redundant functional roles. Metabolomic analysis demonstrated that the sugar-deficient pgkp1pgkp2 double mutation was partially complemented by exogenous sugar, although respiration intermediates were not rescued. Chloroplast development was defective in pgkp1pgkp2, due to a deficiency in glycolysis-dependent galactoglycerolipid biosynthesis. Ectopic expression of a plastid targeting PGKc did not reverse the pgkp1pgkp2 double-mutant phenotypes. Therefore, PGKp1 and PGKp2 play redundant roles in carbon fixation and metabolism, whereas the molecular function of PGKc is more divergent. Our study demonstrated the functional conservation and divergence of glycolytic enzymes.

7.
Environ Sci Pollut Res Int ; 26(13): 12920-12927, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30888621

RESUMO

The effects of manganese content, carrier calcination temperature, and catalyst calcination temperature of manganese-based zirconium pillared intercalated montmorillonite (Mn/Zr-PILM) catalysts were investigated for low-temperature selective catalytic reduction of NOx by NH3 (NH3-SCR) in the metallurgical sintering flue gas. The physicochemical properties of these catalysts can be characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherm, and temperature-programmed desorption of ammonia (NH3-TPD). The 10Mn/Zr400-PILM(300) catalyst had the highest NOx conversion under excess oxygen conditions (15 vol% oxygen) and reached 91.8% NOx conversion at 200 °C. It was found that when the loading of manganese was 10 wt.%, the catalyst had the highest catalytic activity and the manganese-active component was highly dispersed on the Zr-PILM surface. The optimal calcination temperature of the Zr-PILM was 400 °C because the catalyst pore size was concentrated at 1.92 nm and the catalyst had the most acidic sites. And the optimum calcination temperature of the catalyst was 300 °C. This was because excessive calcination temperature promoted the manganese oxide polymerization and reduced the catalytic activity of the catalyst.


Assuntos
Amônia/química , Bentonita/química , Compostos de Manganês/química , Manganês/química , Óxidos/química , Zircônio/química , Adsorção , Catálise , Metalurgia , Temperatura Ambiente , Difração de Raios X
8.
Plant Sci ; 278: 64-69, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30471730

RESUMO

RNA editing in chloroplasts and mitochondria is performed by hypothetical editosomes. The MORF family proteins are essential components of these editosomes. In Arabidopsis, MORF2 and MORF9 are involved in the editing of most sites in chloroplasts. In this work, we performed immunoprecipitation and mass spectrometry assays of transgenic lines expressing MORF2-4xMYC and MORF9-4xMYC to identify interacting proteins. We found that MORF2 and MORF9 are present in the same complex. Blue-Native PAGE analysis of chloroplast protein complexes also revealed that both MORF2 and MORF9 are part of a complex of approximately 140 kDa, suggesting the existence of tight MORF2-MORF9 interaction in chloroplasts. The editing of ndhD-1 (ndhD-C2) site was reported to be blocked in both morf2 and morf9. RNA immunoprecipitation assays showed that MORF2 and MORF9 are tightly associated with the editing site of ndhD-1. However, in an RNA-EMSA assay MORF2 and MORF9 could not directly bind to transcripts harboring the editing site of ndhD-1. Taken together, these results indicate that the MORF2-MORF9 heterodimer is the core members of editosomes in chloroplasts, while they are not responsible for RNA editing site recognition.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/genética , Cloroplastos/genética , Proteínas Mitocondriais/fisiologia , Edição de RNA , Proteínas de Ligação a RNA/fisiologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Eletroforese em Gel de Poliacrilamida , Imunoprecipitação , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Plantas Geneticamente Modificadas/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo
9.
Environ Technol ; : 1-40, 2018 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-30582415

RESUMO

As renewable resource of reducer, biochar prepared by pine saw dust is proposed for copper slag direct reduction in this paper. Combined with thermodynamic analysis, effects of reduction time, temperature and CaO addition ratio on solid copper slag reduction characteristics are discussed. The oxide of iron in copper slag are Fe3O4 and 2FeO·SiO2. The reduction processes are carried out step by step respectively: Fe3O4→FeO→Fe and 2FeO·SiO2→Fe. The porous structure of biochar exhibits higher reduction reactivity and reaction rate than coal. CaO reduced the Gibbs free energy of reduction reactions and facilitated the reduction of 2FeO·SiO2 with C and CO. When CaO was added, separation reaction of FeO and SiO2 take place and α-SiO2 and ß-SiO2 are produced. When addition ratio of CaO is above 0.3, CaO·SiO2 and 2CaO·SiO2 are produced. Reduction process of copper slag was established as follow: (a) dehydration and fast pyrolysis; (b) reduction of iron oxides by C and CO; (c) sweating metallic iron outflows from cracks in pellet. Besides, direct reduction reaction mechanism and transport process of Cu are established based on reduction experiments, XRD and SEM-EDS analysis.

10.
Environ Sci Pollut Res Int ; 25(32): 32122-32129, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30218339

RESUMO

A series of Zr-Fe (Zr/Fe = 4:0, 3:1, 2:2, 1:3, 0:4) polymeric pillared interlayered montmorillonite loading 10 wt.% MnOx (Mn/Zr-Fe-PILM) were investigated for the selective catalytic reduction of NOx by NH3 (NH3-SCR) in metallurgical sintering flue gas. The X-ray diffraction (XRD), N2 adsorption-desorption isotherm, scanning electron microscope (SEM), and ammonia temperature-programmed desorption (NH3-TPD) were used to analyze the physicochemical property. The Fe polymerized with Zr exchanged to montmorillonite can improve the Mn/Zr-Fe-PILM low-temperature NOx conversion and N2 selectivity. The Mn/Zr-Fe-PILM (1:3) shows the highest NOx conversion between 140 and 180 °C. The XRD results suggest that the growth of crystalline ZrO2 phase is intensely restrained for the Fe2O3 migration into the ZrO2 lattice. The ZrO2 and MnOx have an excellent dispersion in montmorillonite. The N2 adsorption result illustrates that the increase of Fe molar content in the Zr-Fe-PILM support increases the catalyst-specific surface area. The NH3-TPD results elucidate that the Mn/Zr-Fe-PILM (1:3) has the most total acid sites. Therefore, the low-temperature catalytic activity of the Mn/Zr-Fe-PILM (1:3) has been assigned to the large specific surface area, abundant acid sites, and the dispersion of metallic oxides.


Assuntos
Amônia/química , Modelos Químicos , Óxido Nítrico/química , Adsorção , Bentonita , Catálise , Temperatura Baixa , Compostos Férricos , Íons , Manganês/química , Metalurgia , Oxirredução , Óxidos/química , Polímeros , Temperatura Ambiente , Difração de Raios X
11.
R Soc Open Sci ; 5(6): 180150, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30110463

RESUMO

In this paper, the relaxation kinetics of the oxidation process of the YBaCo4O7+δ , Y0.95Ti0.05BaCo4O7+δ and Y0.5Dy0.5BaCo4O7+δ oxygen carriers is studied with isothermal reaction data. XRD analysis for fresh samples shows that all the samples have YBaCo4O7+δ structure. Scanning electron microscopy images of samples show that the samples consist of porous agglomerates of primary particles. Isothermal TG experiments are conducted with temperatures of 290°C, 310°C, 330°C and 350°C, respectively. It is found that the Avrami-Eroféev model describes solid-phase changes in the oxygen absorption process adequately. The results show that the distributed activation energies of the oxidation process obtained by the Avrami-Eroféev model are 42.079 kJ mol-1, 42.944 kJ mol-1 and 41.711 kJ mol-1 for the YBaCo4O7+δ , Y0.95Ti0.05BaCo4O7+δ and Y0.5Dy0.5BaCo4O7+δ oxygen carriers, respectively. The kinetic model was obtained to predict the oxygen carrier conversion of oxygen absorption for different time durations. The kinetic parameters obtained here are quite vital when this material is used in reactors.

12.
Environ Technol ; : 1-14, 2018 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-30118387

RESUMO

Selective catalytic reduction of nitrogen oxides (SCR) with loaded urea is a method for removing NO under oxygen-rich and low-temperature conditions, which can solve the inhibitory effect of oxygen on the catalyst and the slip of ammonia. In present study, a series of activated carbon (wo-AC, co-AC, cs-AC and nu-AC) supported metal (Mn, Fe, Co, Cu and Zn) oxide catalysts with loading urea were prepared by ultrasonic assisted impregnation. The catalysts were used for NO removal at 50-120°C and characterized by XRD, SEM, GFAAS, EDS, XPS, BET and FTIR techniques. The effects of activated carbon type, loaded active element, metal oxides loading, temperature fluctuation on catalytic activity and the catalytic stability were also studied in this paper. The results indicated that nutshell-based activated carbon was more suitable as a carrier than other activated carbons, and urea-10Mn/nu-AC catalyst yielded a higher NO conversion than other catalysts. Besides, for used activated carbons, the larger specific surface area, more micropores distribution and the larger number of hydroxyl group and cyano terminal group are beneficial to the catalytic process. Moreover, the downward trend of NO conversion with increasing temperature suggested the adsorption of reactant gases played a crucial role in the catalytic process of urea-SCR.

13.
Sci Rep ; 8(1): 11929, 2018 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-30093718

RESUMO

The expression of plastid genes is regulated by two types of DNA-dependent RNA polymerases, plastid-encoded RNA polymerase (PEP) and nuclear-encoded RNA polymerase (NEP). The plastid rpoA polycistron encodes a series of essential chloroplast ribosome subunits and a core subunit of PEP. Despite the functional importance, little is known about the regulation of rpoA polycistron. In this work, we show that mTERF6 directly associates with a 3'-end sequence of rpoA polycistron in vitro and in vivo, and that absence of mTERF6 promotes read-through transcription at this site, indicating that mTERF6 acts as a factor required for termination of plastid genes' transcription in vivo. In addition, the transcriptions of some essential ribosome subunits encoded by rpoA polycistron and PEP-dependent plastid genes are reduced in the mterf6 knockout mutant. RpoA, a PEP core subunit, accumulates to about 50% that of the wild type in the mutant, where early chloroplast development is impaired. Overall, our functional analyses of mTERF6 provide evidence that it is more likely a factor required for transcription termination of rpoA polycistron, which is essential for chloroplast gene expression and chloroplast development.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Cloroplastos/genética , RNA Polimerases Dirigidas por DNA/genética , Regulação da Expressão Gênica de Plantas , Genes de Cloroplastos/genética , Proteínas Mitocondriais/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Cloroplastos/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Proteínas Mitocondriais/metabolismo , Mutação , Plantas Geneticamente Modificadas , Plastídeos/enzimologia , Plastídeos/genética , Plastídeos/metabolismo , Ribossomos/genética , Ribossomos/metabolismo , Terminação da Transcrição Genética
14.
Photosynth Res ; 137(1): 69-83, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29330702

RESUMO

In higher plant chloroplasts, the plastid-encoded RNA polymerase (PEP) consists of four catalytic subunits and numerous nuclear-encoded accessory proteins, including pTAC10, an S1-domain-containing protein. In this study, pTAC10 knockout lines were characterized. Two ptac10 mutants had an albino phenotype and severely impaired chloroplast development. The pTAC10 genomic sequence fused to a four-tandem MYC tag driven by its own promoter functionally complemented the ptac10-1 mutant phenotype. pTAC10 was present in both the chloroplast stroma and thylakoids. Two-dimensional blue native polyacrylamide gel electrophoresis (BN-PAGE), and immunoblotting assays showed that pTAC10:MYC co-migrates with one of the PEP core subunits, RpoB. A comprehensive investigation of the plastid gene expression profiles by quantitative RT-PCR revealed that, compared with wild-type plants, the abundance of PEP-dependent plastid transcripts is severely decreased in the ptac10-1 mutant, while the amount of plastid transcripts exclusively transcribed by NEP either barely changes or even increases. RNA blot analysis confirmed that PEP-dependent chloroplast transcripts, including psaB, psbA and rbcL, substantially decrease in the ptac10-1 mutant. Immunoblotting showed reduced accumulation of most chloroplast proteins in the ptac10 mutants. These data indicate the essential role of pTAC10 in plastid gene expression and plastid development. pTAC10 interacts with chloroplast-targeted casein kinase 2 (cpCK2) in vitro and in vivo and can be phosphorylated by Arabidopsis cpCK2 in vitro at sites Ser95, Ser396 and Ser434. RNA-EMSA assays showed that pTAC10 is able to bind to the psbA, atpE and accD transcripts, suggesting a non-specific RNA-binding activity of pTAC10. The RNA affinity of pTAC10 was enhanced by phosphorylation and decreased by the amino acid substitution Ser434-Ala of pTAC10. These data show that pTAC10 is essential for plastid gene expression in Arabidopsis and that it can be phosphorylated by cpCK2.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Caseína Quinase II/metabolismo , Proteínas de Cloroplastos/metabolismo , Plastídeos/genética , Substituição de Aminoácidos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Caseína Quinase II/genética , Proteínas de Cloroplastos/genética , Cloroplastos/genética , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Mutação , Fosforilação , Complexo de Proteína do Fotossistema II/genética , Complexo de Proteína do Fotossistema II/metabolismo , Plantas Geneticamente Modificadas , Domínios Proteicos , RNA de Plantas/metabolismo , Tilacoides/metabolismo
15.
Environ Technol ; 39(15): 1878-1885, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28617174

RESUMO

Selective catalytic reduction of nitrogen oxides with carbon monoxide (CO-SCR) is a promising technology to remove NOx and CO simultaneously from flue gas. The thermodynamic analyses of catalytic process were performed toward four kinds of active metal oxides (CuxOy, CoxOy, MnxOy and CexOy). According to the standard Gibbs free-energy changes calculated, Mn had better resistance to oxygen than Cu, Co and Ce, while Cu and Ce had better resistance to water vapor poisoning, as active metals. Then, a series of binary- and ternary-preformed catalysts with different metal ratios were prepared by the impregnation method using Al2O3 pellets as support and tested in excess oxygen (16 vol%) atmosphere with or without SO2. The results of experiment were analyzed based on thermodynamic analyses. Results indicated that the NO conversions of Cu-Co/Al2O3 catalysts increased with the rise of reaction temperature; however, the tendency changed at 160°C for Cu-Mn/Al2O3. Besides, the NO conversions of Cu-Mn/Al2O3 were better than Cu-Co/Al2O3. The catalysts with the metal ratio of 1.5 had the best denitrification performance. Among various binary catalysts, Cu-Mn/Al2O3 with the metal ratio Cu:Mn of 1.5 showed promising activity for CO-SCR, giving nearly 90% NO conversion. Besides, the doping of Ce could inhibit the sulfur poisoning and promote the oxide of CO under experimental conditions.


Assuntos
Monóxido de Carbono/química , Óxido Nítrico/química , Óxido de Alumínio , Catálise , Oxirredução , Oxigênio
16.
Plant J ; 92(4): 546-556, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28850756

RESUMO

The pentatricopeptide repeat-DYW protein AtECB2 affects plastid RNA editing at seven sites, including accD-794, accD-1568, ndhF-290, ndhG-50, petL-5, rpoA-200 and rpoC1-488. To understand the mechanism of its involvement in RNA editing, a transgenic line was constructed with AtECB2 fused to a 4xMYC tag that could complement the atecb2 phenotype. RNA immunoprecipitation analysis indicated that AtECB2 is associated with the transcripts of accD, ndhF, ndhG and petL. Co-immunoprecipitation and mass spectrometry experiments showed that multiple organelle RNA editing factor 2 (MORF2) and porphobilinogen deaminase HEMC are associated with AtECB2. Biochemical analysis showed that AtECB2 directly interacts with HEMC through its E domain, while HEMC interacts with MORF8/RIP1. Deletion analysis showed that the E domain is essential for RNA editing. The hemc-1 mutant showed an albino and seedling-lethal phenotype. Of the seven editing sites affected in atecb2, the editing of accD-794 and ndhF-290 was also reduced in hemc-1. RNA immunoprecipitation analysis suggested that HEMC is associated with the editing sites of ndhF transcripts. These results showed that both HEMC and multiple organellar RNA editing factor (MORF) proteins are associated with AtECB2 for RNA editing in plastids.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Proteínas de Cloroplastos/metabolismo , Hidroximetilbilano Sintase/metabolismo , Edição de RNA , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Clorofila/biossíntese , Proteínas de Cloroplastos/genética , Hidroximetilbilano Sintase/genética , Fator de Crescimento Insulin-Like II , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Modelos Biológicos , Fragmentos de Peptídeos , Fenótipo , Plastídeos/metabolismo , Precursores de Proteínas , RNA de Cloroplastos/genética , Plântula/enzimologia , Plântula/genética , Deleção de Sequência
17.
Physiol Plant ; 161(3): 414-430, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28675462

RESUMO

In higher plants, chloroplasts carry out many important functions, and normal chloroplast development is required for embryogenesis. Numerous chloroplast-targeted proteins involved in embryogenesis have been identified. Nevertheless, their functions remain unclear. In this study, a chloroplast-localized protein, EMB2738, was reported to be involved in Arabidopsis embryogenesis. EMB2738 knockout led to defective embryos, and the embryo development in emb2738 was interrupted after the globular stage. Complementation experiments identified the AT3G12080 locus as EMB2738. Cellular observation indicated that severely impaired chloroplast development was observed in these aborted embryos. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that chloroplast-encoded photosynthetic genes, which are transcribed by plastid-encoded RNA polymerase (PEP), are predominantly decreased in defective embryogenesis, compared with those in the wild-type. In contrast, genes encoding PEP core subunits, which are transcribed by nucleus-encoded RNA polymerase (NEP), were increased. These results suggested that the knockout of EMB2738 strongly blocked chloroplast-encoded photosynthesis gene expression in embryos. Silencing of the EMB2738 orthologue in tobacco through a virus-induced genome silencing technique resulted in an albinism phenotype, vacuolated chloroplasts and decreased PEP-dependent plastid transcription. These results suggested that NtEMB2738 might be involved in plastid gene expression. Nevertheless, genetic analysis showed that the NtEMB2738 coding sequence could not fully rescue the defective embryogenesis of the emb2738 mutant, which suggested functional divergence between NtEMB2738 and EMB2738 in embryogenesis. Taken together, these results indicated that both EMB2738 and NtEMB2738 are involved in the expression of plastid genes in higher plants, and there is a functional divergence between NtEMB2738 and EMB2738 in embryogenesis.


Assuntos
Arabidopsis/embriologia , Cloroplastos/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Proteínas de Plantas/metabolismo , Tabaco/embriologia , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/ultraestrutura , Cloroplastos/ultraestrutura , Cruzamentos Genéticos , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Inativação Gênica , Teste de Complementação Genética , Mutação/genética , Fenótipo , Filogenia , Proteínas de Plantas/genética , Transporte Proteico , Sementes/embriologia , Sementes/genética , Sementes/ultraestrutura , Análise de Sequência de Proteína , Tabaco/genética , Transcrição Genética
18.
Mater Sci Eng C Mater Biol Appl ; 76: 918-924, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28482607

RESUMO

Polyvinyl alcohol (PVA) micelles were firstly synthesized by using hemin molecules as novel crosslinked bridges (PVA-H crosslinked micelles). On one hand, the crosslinked micelles can allow high stability against extensive dilution (1800-fold) to reduce side-effects; On the other hand, the bridges not only can destruct by means of laser irradiation (405nm, 200mw), but also can induce the production of singlet oxygen (1O2) and the release of 5-fluorouracil (5FU) (i.e. 46% release in 360min). But above all, that 5FU-loaded PVA-H crosslinked micelles irradiating by laser is more efficient than PVA-H crosslinked micelles and free 5FU in killing tumor cells, suggest the effective synergistic antitumor effect about chemotherapy and photodynamic therapy (PDT).


Assuntos
Álcool de Polivinil/química , Fluoruracila , Micelas , Fotoquimioterapia , Cloreto de Polivinila
19.
Sci Rep ; 6: 35998, 2016 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-27782173

RESUMO

Mesenchymal stem cells (MSCs) are generally used in regenerative medicine, tissue engineering and therapy for immune disorder diseases. However, due to the immunosuppressive function of MSCs, the application of MSCs in breast cancer therapy remains limited. Sirt1 is the closest mammalian homologue of the yeast enzyme Sir2 which has an established capacity to influence yeast replicative lifespan. In this study, we demonstrated the effect of MSCs with Sirt1 overexpression (MSCs-Sirt1) in mice bearing 4T1 breast cancer and investigated the underlying mechanism. Firstly, we found that MSCs could accelerate breast tumor growth with promoted proliferation and inhibited apoptosis, whereas MSCs-Sirt1 significantly suppressed tumor growth with proliferation inhibition and apoptosis promotion. Moreover, we detected that NK cells were the prominent antitumor effectors for the MSCs-Sirt1-induced antitumor activity. Besides that, CXCL10 and IFN-γ showed the high level expression in MSCs-Sirt1 treatment group. The impulsive effect of MSCs-Sirt1 on 4T1 cells in vivo could be reversed by inhibition of CXCL10 and IFN-γ. Overall, our results suggest that MSCs-Sirt1 can effectively inhibit breast tumor growth via the recruitment of NK cells in tumor inflammatory microenvironment.


Assuntos
Células Matadoras Naturais/imunologia , Neoplasias Mamárias Experimentais/imunologia , Neoplasias Mamárias Experimentais/terapia , Células-Tronco Mesenquimais/enzimologia , Células-Tronco Mesenquimais/imunologia , Sirtuína 1/metabolismo , Animais , Apoptose , Linhagem Celular Tumoral , Proliferação de Células , Quimiocina CXCL10/metabolismo , Quimiocinas/metabolismo , Feminino , Interferon gama/metabolismo , Neoplasias Mamárias Experimentais/patologia , Transplante de Células-Tronco Mesenquimais , Camundongos , Camundongos Endogâmicos BALB C , Sirtuína 1/genética , Microambiente Tumoral/imunologia , Regulação para Cima
20.
PLoS One ; 11(5): e0154235, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27137770

RESUMO

Chloroplast function in photosynthesis is essential for plant growth and development. It is well-known that chloroplasts respond to various light conditions. However, it remains poorly understood about how chloroplasts respond to darkness. In this study, we found 81 darkness-responsive proteins in Arabidopsis chloroplasts under 8 h darkness treatment. Most of the proteins are nucleus-encoded, indicating that chloroplast darkness response is closely regulated by the nucleus. Among them, 17 ribosome proteins were obviously reduced after darkness treatment. The protein expressional patterns and physiological changes revealed the mechanisms in chloroplasts in response to darkness, e.g., (1) inhibition of photosystem II resulted in preferential cyclic electron flow around PSI; (2) promotion of starch degradation; (3) inhibition of chloroplastic translation; and (4) regulation by redox and jasmonate signaling. The results have improved our understanding of molecular regulatory mechanisms in chloroplasts under darkness.


Assuntos
Arabidopsis/metabolismo , Arabidopsis/efeitos da radiação , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Escuridão , Proteômica , Proteínas de Arabidopsis/metabolismo , Metabolismo dos Carboidratos/efeitos da radiação , Clorofila/metabolismo , Fotossíntese/efeitos da radiação , Ribulose-Bifosfato Carboxilase/metabolismo , Amido/metabolismo
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