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Search Results: 1 - 10 of 8438 matches for " Wanyin Deng "
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The Salmonella enterica PhoP Directly Activates the Horizontally Acquired SPI-2 Gene sseL and Is Functionally Different from a S. bongori Ortholog
Ohad Gal-Mor,Dana Elhadad,Wanyin Deng,Galia Rahav,Brett B. Finlay
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020024
Abstract: To establish a successful infection within the host, a pathogen must closely regulate multiple virulence traits to ensure their accurate temporal and spatial expression. As a highly adapted intracellular pathogen, Salmonella enterica has acquired during its evolution various virulence genes via numerous lateral transfer events, including the acquisition of the Salmonella Pathogenicity Island 2 (SPI-2) and its associated effectors. Beneficial use of horizontally acquired genes requires that their expression is effectively coordinated with the already existing virulence programs and the regulatory set-up in the bacterium. As an example for such a mechanism, we show here that the ancestral PhoPQ system of Salmonella enterica is able to regulate directly the SPI-2 effector gene sseL (encoding a secreted deubiquitinase) in an SsrB-independent manner and that PhoP plays a part in a feed-forward regulatory loop, which fine-tunes the cellular level of SseL. Additionally, we demonstrate the presence of conserved cis regulatory elements in the promoter region of sseL and show direct binding of purified PhoP to this region. Interestingly, in contrast to the S. enterica PhoP, an ortholog regulator from a S. bongori SARC 12 strain was found to be impaired in promoting transcription of sseL and other genes from the PhoP regulon. These findings have led to the identification of a previously uncharacterized residue in the DNA-binding domain of PhoP, which is required for the transcriptional activation of PhoP regulated genes in Salmonella spp. Collectively our data demonstrate an interesting interface between the acquired SsrB regulon and the ancestral PhoPQ regulatory circuit, provide novel insights into the function of PhoP, and highlight a mechanism of regulatory integration of horizontally acquired genes into the virulence network of Salmonella enterica.
THE KARYOTYPE ANALYSIS OF RICE (ORYZA SATIVA)
水稻(Oryza sativa)核型分析

Shu Lihui,Deng Wanyin,Li Guopu,
舒理慧
,邓万银,李国圃

植物科学学报 , 1985,
Abstract: The karyotype analysis based on mitotic cells in rice, Oryza sativa L. (2n=24), was conducted. Root tips were treated with KCl and enzyme and stained with Giemsa. Twelve pairs of chromosomes are arranged according to the length. The karyotype of rice analysed in this work is n =5m+6sm+1st and 2 pairs of satellite chromosomes were observed in numerous cells.
Bacterial Effector Binding to Ribosomal Protein S3 Subverts NF-κB Function
Xiaofei Gao,Fengyi Wan,Kristina Mateo,Eduardo Callegari,Dan Wang,Wanyin Deng,Jose Puente,Feng Li,Michael S. Chaussee,B. Brett Finlay,Michael J. Lenardo,Philip R. Hardwidge
PLOS Pathogens , 2009, DOI: 10.1371/journal.ppat.1000708
Abstract: Enteric bacterial pathogens cause food borne disease, which constitutes an enormous economic and health burden. Enterohemorrhagic Escherichia coli (EHEC) causes a severe bloody diarrhea following transmission to humans through various means, including contaminated beef and vegetable products, water, or through contact with animals. EHEC also causes a potentially fatal kidney disease (hemolytic uremic syndrome) for which there is no effective treatment or prophylaxis. EHEC and other enteric pathogens (e.g., enteropathogenic E. coli (EPEC), Salmonella, Shigella, Yersinia) utilize a type III secretion system (T3SS) to inject virulence proteins (effectors) into host cells. While it is known that T3SS effectors subvert host cell function to promote diarrheal disease and bacterial transmission, in many cases, the mechanisms by which these effectors bind to host proteins and disrupt the normal function of intestinal epithelial cells have not been completely characterized. In this study, we present evidence that the E. coli O157:H7 nleH1 and nleH2 genes encode T3SS effectors that bind to the human ribosomal protein S3 (RPS3), a subunit of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional complexes. NleH1 and NleH2 co-localized with RPS3 in the cytoplasm, but not in cell nuclei. The N-terminal region of both NleH1 and NleH2 was required for binding to the N-terminus of RPS3. NleH1 and NleH2 are autophosphorylated Ser/Thr protein kinases, but their binding to RPS3 is independent of kinase activity. NleH1, but not NleH2, reduced the nuclear abundance of RPS3 without altering the p50 or p65 NF-κB subunits or affecting the phosphorylation state or abundance of the inhibitory NF-κB chaperone IκBα NleH1 repressed the transcription of a RPS3/NF-κB-dependent reporter plasmid, but did not inhibit the transcription of RPS3-independent reporters. In contrast, NleH2 stimulated RPS3-dependent transcription, as well as an AP-1-dependent reporter. We identified a region of NleH1 (N40-K45) that is at least partially responsible for the inhibitory activity of NleH1 toward RPS3. Deleting nleH1 from E. coli O157:H7 produced a hypervirulent phenotype in a gnotobiotic piglet model of Shiga toxin-producing E. coli infection. We suggest that NleH may disrupt host innate immune responses by binding to a cofactor of host transcriptional complexes.
Measuring the velocity of sand particles in an air/particle two-phase flow: A comparison of several commonly used methods

Zhibao Dong,GuangQiang Qian,WanYin Luo,HongTao Wang,

寒旱区科学 , 2010,
Abstract: The velocity of blown sand particles is an important parameter in aeolian movement (a special case of gas particle two-phase flow) and has ever been a topic of interest. At present, several techniques have been applied in measuring velocity of the blown sand particles. This paper reviews the measurement results of several commonly used methods: photoelectric cell method, high-speed photographic method, Particle Dynamics Analyzer (PDA) method and Particle Image Velocimetry (PIV) method. Photoelectric cell method, high-speed photograph method and PDA method are useful in studying the velocity distribution of particles. PIV is a whole-flow-field technique and a useful tool to study the average velocity field in a target area. These methods got some similar results but considerable differences also exist. They have come to similar conclusions on the velocity distributions at a single height but direct measurement results with respect to the velocity distribution very close to the surface are still scarce except some PDA results. The magnitude of measured mean particle velocity differs greatly. The relationship obtained by different methods between mean particle velocity and wind velocity, particle size and possibly other influencing factors also differs considerably. Although several authors have proposed similar power functions to describe the variation with height of the mean particle velocity, the predicted results have wide differences. Each technique is based on some unique principles, and has its advantages and disadvantages. To make full use of different techniques, a lot of work needs be done to validate them. Developing a reliable technique to measure the velocity of blown particles is still a necessary task in aeolian research.
Effects of geomorphic conditions, wind speed, and precipitation on dustfall over northern China

JinChang Li,ZhiBao Dong,GuangQiang Qian,WanYin Luo,

寒旱区科学 , 2010,
Abstract: We investigated how dustfall flux (DF) and dust particle size (DPS) were affected by geomorphic conditions, wind speed, and precipitation using data from 27 sites in northern China. The sites with the greatest DF and greatest median diameter of dustfall (MDD) were primarily in desert regions and had extensive mobile sands. DF and MDD were lowest in agricultural regions, which had low levels of coarse particles because of human land use and high vegetation coverage that restrained blowing sand. DF values were higher and MDD values were lower in the western agricultural region than in the eastern agricultural region because the former is closer to desert regions and contains more fine dust that has traveled far. In regions with extensive desertified lands, DF values were lower than those in desert regions, and MDD values were greater than in agricultural regions, possibly due to coarsening of soil texture by desertification processes combined with higher vegetation coverage and soil moisture than in desert regions, thereby restraining blowing sand. Although high DF and MDD always coincided spatially with strong winds and low precipitation, the strong winds and low precipitation did not always mean high DF and MDD. High DF also coincided temporally with periods of low precipitation, but low precipitation did not always mean high DF. Thus, although the spatial trends in DF and DPS were controlled mostly by geomorphic conditions, and monthly trends in DF were controlled mainly by wind speed, weak wind and high precipitation can restrain the blowing sand at certain times and locations. Seasonal changes in DPS may be controlled simultaneously by geomorphic conditions, meteorological factors, and distance from source areas, not solely by the winter monsoon.
Spatial trends of dustfall over northern China in the spring and their influencing factors

JinChang Li,ZhiBao Dong,GuangQiang Qian,WanYin Luo,

寒旱区科学 , 2010,
Abstract:
Threshold wind velocity in the lee of two-dimensional transverse dunes

ZhiBao Dong,HongTao Wang,GuangQiang Qian,WanYin Luo,

寒旱区科学 , 2010,
Abstract: Secondary flow plays an important role in the development of dunes. To investigate this phenomenon, we simulated models of transverse dunes with different stoss slopes in a wind tunnel. We measured the threshold wind velocity at different locations in the lee of the dunes, and observed the corresponding particle movement characteristics under threshold conditions to assess the sedimentological significance of secondary airflow. Threshold wind velocity changed with both horizontal distance and stoss slope. Its variation with horizontal distance is characterized by a region in which a rapid reduction occurs, a region with a minimum value, and a region with high value. We confirmed the presence of reversal cells, irrespective of the stoss slope. Neither the variation in threshold wind velocity nor the variation in reattachment distance as a function of stoss slope followed a monotonic function. The 15° stoss slope had the greatest threshold wind velocity and reattachment distance.
Aeolian dust transportation and deposition by near-surface winds in arid and semiarid China

JinChang Li,ZhiBao Dong,GuangQiang Qian,WanYin Luo,

寒旱区科学 , 2010,
Abstract:
Evaluating the optimal porosity of fences for reducing wind erosion

ZhiBao Dong,WanYin Luo,GuangQiang Qian,HongTao Wang,

寒旱区科学 , 2011,
Abstract:
Momentum profile of aeolian saltation cloud

ZhiBao Dong,WanYin Luo,GuangQiang Qian,HongTao Wang,

寒旱区科学 , 2009,
Abstract:
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