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Search Results: 1 - 10 of 13580 matches for " Baofang Fan "
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Roles of Arabidopsis WRKY3 and WRKY4 Transcription Factors in Plant Responses to Pathogens
Zhibing Lai, KM Vinod, Zuyu Zheng, Baofang Fan, Zhixiang Chen
BMC Plant Biology , 2008, DOI: 10.1186/1471-2229-8-68
Abstract: Both WRKY3 and WRKY4 are nuclear-localized and specifically recognize the TTGACC W-box sequences in vitro. Expression of WRKY3 and WRKY4 was induced rapidly by stress conditions generated by liquid infiltration or spraying. Stress-induced expression of WRKY4 was further elevated by pathogen infection and SA treatment. To determine directly their role in plant disease resistance, we have isolated T-DNA insertion mutants and generated transgenic overexpression lines for WRKY3 and WRKY4. Both the loss-of-function mutants and transgenic overexpression lines were examined for responses to the biotrophic bacterial pathogen Pseudomonas syringae and the necrotrophic fungal pathogen Botrytis cinerea. The wrky3 and wrky4 single and double mutants exhibited more severe disease symptoms and support higher fungal growth than wild-type plants after Botrytis infection. Although disruption of WRKY3 and WRKY4 did not have a major effect on plant response to P. syringae, overexpression of WRKY4 greatly enhanced plant susceptibility to the bacterial pathogen and suppressed pathogen-induced PR1 gene expression.The nuclear localization and sequence-specific DNA-binding activity support that WRKY3 and WRKY4 function as transcription factors. Functional analysis based on T-DNA insertion mutants and transgenic overexpression lines indicates that WRKY3 and WRKY4 have a positive role in plant resistance to necrotrophic pathogens and WRKY4 has a negative effect on plant resistance to biotrophic pathogens.Upon pathogen infection, pathogen-associated molecular patterns (PAMPs) such as bacterial flagellin and lipopolysaccharides are recognized by plant receptors to activate PAMP-triggered immunity through a mitogen-activated protein kinase signaling cascade [1]. Gram-negative bacterial pathogens such as Pseudomonas syringae can deliver effector proteins to plant cells to interfere PAMP-triggered resistance to promote pathogen virulence. As a result, the remaining basal defense is usually insuffi
Functional analysis of Arabidopsis WRKY25 transcription factor in plant defense against Pseudomonas syringae
Zuyu Zheng, Stephen L Mosher, Baofang Fan, Daniel F Klessig, Zhixiang Chen
BMC Plant Biology , 2007, DOI: 10.1186/1471-2229-7-2
Abstract: We analyzed the role of the WRKY25 transcription factor from Arabidopsis in plant defense against the bacterial pathogen Pseudomonas syringae. WRKY25 protein recognizes the TTGACC W-box sequences and its translational fusion with green fluorescent protein is localized to the nucleus. WRKY25 expression is responsive to general environmental stress. Analysis of stress-induced WRKY25 in the defense signaling mutants npr1, sid2, ein2 and coi1 further indicated that this gene is positively regulated by the salicylic acid (SA) signaling pathway and negatively regulated by the jasmonic acid signaling pathway. Two independent T-DNA insertion mutants for WRKY25 supported normal growth of a virulent strain of P. syringae but developed reduced disease symptoms after infection. By contrast, Arabidopsis constitutively overexpressing WRKY25 supported enhanced growth of P. syringae and displayed increased disease symptom severity as compared to wild-type plants. These WRKY25-overexpressing plants also displayed reduced expression of the SA-regulated PR1 gene after the pathogen infection, despite normal levels of free SA.The nuclear localization and sequence-specific DNA-binding activity support that WRKY25 functions as a transcription factor. Based on analysis of both T-DNA insertion mutants and transgenic overexpression lines, stress-induced WRKY25 functions as a negative regulator of SA-mediated defense responses to P. syringae. This proposed role is consistent with the recent finding that WRKY25 is a substrate of Arabidopsis MAP kinase 4, a repressor of SA-dependent defense responses.Plants are subjected to constant attack by a variety of microbial pathogens and herbivores and they have evolved a complex battery of defense mechanisms that are activated by multiple defense signaling pathways. Thus, in response to infection by some microbial pathogens, the interacting EDS1 and PAD4 proteins are induced and activated; these proteins positively regulate biosynthesis of salicylic ac
Arabidopsis LIP5, a Positive Regulator of Multivesicular Body Biogenesis, Is a Critical Target of Pathogen-Responsive MAPK Cascade in Plant Basal Defense
Fei Wang,Yifen Shang,Baofang Fan,Jing-Quan Yu,Zhixiang Chen
PLOS Pathogens , 2014, DOI: doi/10.1371/journal.ppat.1004243
Abstract: Multivesicular bodies (MVBs) play essential roles in many cellular processes. The MVB pathway requires reversible membrane association of the endosomal sorting complexes required for transports (ESCRTs) for sustained protein trafficking. Membrane dissociation of ESCRTs is catalyzed by the AAA ATPase SKD1, which is stimulated by LYST-INTERACTING PROTEIN 5 (LIP5). We report here that LIP5 is a target of pathogen-responsive mitogen-activated protein kinases (MPKs) and plays a critical role in plant basal resistance. Arabidopsis LIP5 interacts with MPK6 and MPK3 and is phosphorylated in vitro by activated MPK3 and MPK6 and in vivo upon expression of MPK3/6-activating NtMEK2DD and pathogen infection. Disruption of LIP5 has little effects on flg22-, salicylic acid-induced defense responses but compromises basal resistance to Pseudomonas syringae. The critical role of LIP5 in plant basal resistance is dependent on its ability to interact with SKD1. Mutation of MPK phosphorylation sites in LIP5 does not affect interaction with SKD1 but reduces the stability and compromises the ability to complement the lip5 mutant phenotypes. Using the membrane-selective FM1–43 dye and transmission electron microscopy, we demonstrated that pathogen infection increases formation of both intracellular MVBs and exosome-like paramural vesicles situated between the plasma membrane and the cell wall in a largely LIP5-dependent manner. These results indicate that the MVB pathway is positively regulated by pathogen-responsive MPK3/6 through LIP5 phosphorylation and plays a critical role in plant immune system likely through relocalization of defense-related molecules.
E3 Ubiquitin Ligase CHIP and NBR1-Mediated Selective Autophagy Protect Additively against Proteotoxicity in Plant Stress Responses
Jie Zhou equal contributor,Yan Zhang equal contributor,Jingxia Qi,Yingjin Chi,Baofang Fan,Jing-Quan Yu,Zhixiang Chen
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004116
Abstract: Plant stress responses require both protective measures that reduce or restore stress-inflicted damage to cellular structures and mechanisms that efficiently remove damaged and toxic macromolecules, such as misfolded and damaged proteins. We have recently reported that NBR1, the first identified plant autophagy adaptor with a ubiquitin-association domain, plays a critical role in plant stress tolerance by targeting stress-induced, ubiquitinated protein aggregates for degradation by autophagy. Here we report a comprehensive genetic analysis of CHIP, a chaperone-associated E3 ubiquitin ligase from Arabidopsis thaliana implicated in mediating degradation of nonnative proteins by 26S proteasomes. We isolated two chip knockout mutants and discovered that they had the same phenotypes as the nbr1 mutants with compromised tolerance to heat, oxidative and salt stresses and increased accumulation of insoluble proteins under heat stress. To determine their functional interactions, we generated chip nbr1 double mutants and found them to be further compromised in stress tolerance and in clearance of stress-induced protein aggregates, indicating additive roles of CHIP and NBR1. Furthermore, stress-induced protein aggregates were still ubiquitinated in the chip mutants. Through proteomic profiling, we systemically identified heat-induced protein aggregates in the chip and nbr1 single and double mutants. These experiments revealed that highly aggregate-prone proteins such as Rubisco activase and catalases preferentially accumulated in the nbr1 mutant while a number of light-harvesting complex proteins accumulated at high levels in the chip mutant after a relatively short period of heat stress. With extended heat stress, aggregates for a large number of intracellular proteins accumulated in both chip and nbr1 mutants and, to a greater extent, in the chip nbr1 double mutant. Based on these results, we propose that CHIP and NBR1 mediate two distinct but complementary anti-proteotoxic pathways and protein's propensity to aggregate under stress conditions is one of the critical factors for pathway selection of protein degradation.
NBR1-Mediated Selective Autophagy Targets Insoluble Ubiquitinated Protein Aggregates in Plant Stress Responses
Jie Zhou equal contributor,Jian Wang equal contributor,Yuan Cheng,Ying-Jun Chi,Baofang Fan,Jing-Quan Yu,Zhixiang Chen
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003196
Abstract: Plant autophagy plays an important role in delaying senescence, nutrient recycling, and stress responses. Functional analysis of plant autophagy has almost exclusively focused on the proteins required for the core process of autophagosome assembly, but little is known about the proteins involved in other important processes of autophagy, including autophagy cargo recognition and sequestration. In this study, we report functional genetic analysis of Arabidopsis NBR1, a homolog of mammalian autophagy cargo adaptors P62 and NBR1. We isolated two nbr1 knockout mutants and discovered that they displayed some but not all of the phenotypes of autophagy-deficient atg5 and atg7 mutants. Like ATG5 and ATG7, NBR1 is important for plant tolerance to heat, oxidative, salt, and drought stresses. The role of NBR1 in plant tolerance to these abiotic stresses is dependent on its interaction with ATG8. Unlike ATG5 and ATG7, however, NBR1 is dispensable in age- and darkness-induced senescence and in resistance to a necrotrophic pathogen. A selective role of NBR1 in plant responses to specific abiotic stresses suggest that plant autophagy in diverse biological processes operates through multiple cargo recognition and delivery systems. The compromised heat tolerance of atg5, atg7, and nbr1 mutants was associated with increased accumulation of insoluble, detergent-resistant proteins that were highly ubiquitinated under heat stress. NBR1, which contains an ubiquitin-binding domain, also accumulated to high levels with an increasing enrichment in the insoluble protein fraction in the autophagy-deficient mutants under heat stress. These results suggest that NBR1-mediated autophagy targets ubiquitinated protein aggregates most likely derived from denatured or otherwise damaged nonnative proteins generated under stress conditions.
Deterministic and stochastic aspects of the transition to turbulence
Baofang Song,Bj?rn Hof
Statistics , 2014, DOI: 10.1088/1742-5468/2014/02/P02001
Abstract: The purpose of this contribution is to summarize and discuss recent advances regarding the onset of turbulence in shear flows. The absence of a clear cut instability mechanism, the spatio-temporal intermittent character and extremely long lived transients are some of the major difficulties encountered in these flows and have hindered progress towards understanding the transition process. We will show for the case of pipe flow that concepts from nonlinear dynamics and statistical physics can help to explain the onset of turbulence. In particular the turbulent structures ('puffs') observed close to onset are spatially localized chaotic transients and their lifetimes increase super exponentially with Reynolds number. At the same time fluctuations of individual turbulent puffs can (although very rarely) lead to the nucleation of new puffs. The competition between these two stochastic processes gives rise to a non-equilibrium phase transition where turbulence changes from a super-transient to a sustained state.
Analyze the Economic Value of Accounting Integrity in Market Mechanism
Aihua Li,Lei Chen,Baofang Dong
Journal of Sustainable Development , 2010, DOI: 10.5539/jsd.v3n1p169
Abstract: This paper analyzes the economic value of accounting integrity, agreeing that accounting integrity can decrease trading costs, improve enterprises’ operational efficiency, enlarge market shares and competitiveness, evaluate and motive economic subjects, drive the formation and development of social capitals, and actualize the economy of scale.
Dietary Supplementation of Blueberry Juice Enhances Hepatic Expression of Metallothionein and Attenuates Liver Fibrosis in Rats
Yuping Wang, Mingliang Cheng, Baofang Zhang, Fei Nie, Hongmei Jiang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058659
Abstract: Aim To investigate the effect of blueberry juice intake on rat liver fibrosis and its influence on hepatic antioxidant defense. Methods Rabbiteye blueberry was used to prepare fresh juice to feed rats by daily gastric gavage. Dan-shao-hua-xian capsule (DSHX) was used as a positive control for liver fibrosis protection. Liver fibrosis was induced in male Sprague-Dawley rats by subcutaneous injection of CCl4 and feeding a high-lipid/low-protein diet for 8 weeks. Hepatic fibrosis was evaluated by Masson staining. The expression of α-smooth muscle actin (α-SMA) and collagen III (Col III) were determined by immunohistochemical techniques. The activities of superoxide dismutase (SOD) and malondialdehyde (MDA) in liver homogenates were determined. Metallothionein (MT) expression was detected by real-time RT-PCR and immunohistochemical techniques. Results Blueberry juice consumption significantly attenuates CCl4-induced rat hepatic fibrosis, which was associated with elevated expression of metallothionein (MT), increased SOD activity, reduced oxidative stress, and decreased levels of α-SMA and Col III in the liver. Conclusion Our study suggests that dietary supplementation of blueberry juice can augment antioxidative capability of the liver presumably via stimulating MT expression and SOD activity, which in turn promotes HSC inactivation and thus decreases extracellular matrix collagen accumulation in the liver, and thereby alleviating hepatic fibrosis.
Effects of the Yangjing Capsule Extract on Steroidogenesis and Apoptosis in Mouse Leydig Cells
Dalin Sun,Yugui Cui,Baofang Jin,Xindong Zhang,Xiaoyu Yang,Chao Gao
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/985457
Abstract: Objectives. This study aimed to explore the effect and mechanism of Yangjing capsule on testosterone secretion in mouse Leydig tumor cells (MLTC-1). Methods. MLTC-1 cells were treated with the Yangjing capsule extract for 24 h. The testosterone level in medium was measured by radioimmunoassay. The expression of steroidogenic enzymes (StAR, CYP11A1, and HSD3B) in the cells was examined using real-time RT-PCR and immunoblotting. Additionally, MLTC-1 cells were treated for 48 h in a serum-free medium. The cell viability was measured by MTT assay. The cell cycle and apoptosis were analyzed using flow cytometry. The expression of activated caspase-3 was analyzed using RT-PCR and a colorimetric protease assay. Results. The Yangjing capsule extract increased testosterone production and the expression of StAR, CYP11A1, and HSD3B mRNAs and proteins compared with the control. H89 significantly inhibited these effects. The medicine improved the viability of MLTC-1 cells, decreased the number of cells in G0/G1 phase, and increased the number of cells in S-phase, as well as prevented cell apoptosis by inhibiting caspase-3. Conclusion. The Yangjing capsule can stimulate MLTC-1 cells to secrete testosterone and may be an alternative treatment for diseases characterized by insufficient testosterone production.
pH dependence of the protein orientation in self-assembled bacteriorhodopsin/polycation multilayer films
Tapio Jussila,Meiling Li,Nikolai V. Tkachenko,Sinikka Parkkinen,Baofang Li,Long Jiang,Helge Lemmetyinen
International Journal of Photoenergy , 2000, DOI: 10.1155/s1110662x00000064
Abstract: Bacteriorhodopsin (bR) multilayer films were successfully prepared by alternatingdepositions of cationic poly(diallyldimethylammonium chloride) (PDAC) polyelectrolyte and purple membrane (PM). The advantage of the method when compared to other thin film techniques is its simplicity to prepare large selfassembled films. The orientations of the bR molecules in the films were studied by a transient photovoltage method. The polarity of the photoresponse signals showed that in basic conditions the cytoplasmic side of PM was adsorbed onto the polyelectrolyte layer, whereas in acidic conditions the extracellular side was adsorbed onto the polyelectrolyte layer. The photocycle of the bR in the films was studied by usingthe conventional flash photolysis method. The photochemical behavior of bR in dry polycationic films was similar to that in other types of dry films and the intermediate lifetimes were almost independent of the protein orientation.
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