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Search Results: 1 - 10 of 8321 matches for " Xuehong Qiu "
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Genetic and Proteomic Characterization of rpoB Mutations and Their Effect on Nematicidal Activity in Photorhabdus luminescens LN2
Xuehong Qiu, Xun Yan, Mingxing Liu, Richou Han
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043114
Abstract: Rifampin resistant (RifR) mutants of the insect pathogenic bacterium Photorhabdus luminescens LN2 from entomopathogenic nematode Heterorhabditis indica LN2 were genetically and proteomically characterized. The RifR mutants showed typical phase one characters of Photorhabdus bacteria, and insecticidal activity against Galleria mellonella larvae, but surprisingly influenced their nematicidal activity against axenic infective juveniles (IJs) of H. bacteriophora H06, an incompatible nematode host. 13 out of 34 RifR mutants lost their nematicidal activity against H06 IJs but supported the reproduction of H06 nematodes. 7 nematicidal-producing and 7 non-nematicidal-producing RifR mutants were respectively selected for rpoB sequence analysis. rpoB mutations were found in all 14 RifR mutants. The rpoB (P564L) mutation was found in all 7 mutants which produced nematicidal activity against H06 nematodes, but not in the mutants which supported H06 nematode production. Allelic exchange assays confirmed that the Rif-resistance and the impact on nematicidal activity of LN2 bacteria were conferred by rpoB mutation(s). The non-nematicidal-producing RifR mutant was unable to colonize in the intestines of H06 IJs, but able to colonize in the intestines of its indigenous LN2 IJs. Proteomic analysis revealed different protein expression between wild-type strain and RifR mutants, or between nematicidal-producing and non nematicidal-producing mutants. At least 7 putative proteins including DsbA, HlpA, RhlE, RplC, NamB (a protein from T3SS), and 2 hypothetical proteins (similar to unknown protein YgdH and YggE of Escherichia coli respectively) were probably involved in the nematicidal activity of LN2 bacteria against H06 nematodes. This hypothesis was further confirmed by creating insertion-deletion mutants of three selected corresponding genes (the downregulated rhlE and namB, and upregualted dsbA). These results indicate that the rpoB mutations greatly influence the symbiotic association between the symbionts and their entomopathogenic nematode hosts.
Backward stochastic viability property with jumps and applications to the comparison theorem for multidimensional BSDEs with jumps
Xuehong Zhu
Mathematics , 2010,
Abstract: In this paper, we study conditions under which the solutions of a backward stochastic differential equation with jump remains in a given set of constrains. This property is the so-called "viability property". As an application, we study the comparison theorem for multidimensional BSDEs with jumps.
On the comparison theorem for multidimensional SDEs with jumps
Xuehong Zhu
Mathematics , 2010,
Abstract: In this note, we give a necessary and sufficient condition under which the comparison theorem holds for multidimensional stochastic differential equations (SDEs) with jumps and for matrix-valued SDEs with jumps.
Viscosity solutions to second order parabolic PDEs on Riemannian manifolds
Xuehong Zhu
Mathematics , 2010,
Abstract: In this work we consider viscosity solutions to second order parabolic PDEs $u_{t}+F(t,x,u,du,d^{2}u)=0$ defined on compact Riemannian manifolds with boundary conditions. We prove comparison, uniqueness and existence results for the solutions. Under the assumption that the manifold $M$ has nonnegative sectional curvature, we get the finest results. If one additionally requires $F$ to depend on $d^{2}u$ in a uniformly continuous manner, the assumptions on curvature can be thrown away.
The optimal control related to Riemannian manifolds and the viscosity solutions to H-J-B equations
Xuehong Zhu
Mathematics , 2010,
Abstract: This paper is concerned with the Dynamic Programming Principle (DPP in short) with SDEs on Riemannian manifolds. Moreover, through the DPP, we conclude that the cost function is the unique viscosity solution to the related PDEs on manifolds.
The viability property of jump diffusion processes on Riemannian manifolds
Xuehong Zhu
Mathematics , 2010,
Abstract: In this note, we consider the necessary and sufficient condition for viability property of diffusion processes with jumps on closed submanifolds of $R^{m}$ with some concrete examples.
A Simulation Study on Channel Estimation for Cooperative Communication System in Sand-dust Storm Environment  [PDF]
Xuehong Sun, Yu Cao, Jin Che
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53B2004
Abstract: There are many factors that influence the propagation of electromagnetic wave in the sand-dust storm environment, the scattering effect of dust particle is one of the major factors, so this paper focuses on the dust particles scattering function. The scattering of dust particles inevitably brings the multipath transmission of the signal, multipath propagation will bring the multipath fading of the signal. In this paper, we first investigate the use of AF and DF modes in a sand-dust storm environment. Secondly, we present a low-order modulation method should be used in cooperative communication system. Lastly, we evaluate the system performance for both of the moving nodes and power allocation. Experimental results validate the conclusion of theoretical derivation: the multipath fading is one of the main factors that affect the quality of signal transmission. Cooperative communication technology has good anti-fading ability, which can guarantee the signal transmission timely and correctly.
Microwave Synthesis of Ce/BiVO4 Nanocomposites Photocatalyst and Their Photocatalytic Properties  [PDF]
Mingcui Tuo, Shuibin Yang, Xuehong Liao
Open Journal of Composite Materials (OJCM) , 2018, DOI: 10.4236/ojcm.2018.82006
Abstract: Ce/BiVO4 nanocomposites photocatalyst was synthesized by direct feeding microwave synthesis method, using bismuth nitrate (Bi (NO3)3·5H2O), cerium?nitrate hexahydrate (Ce (NO3)3·6H2O) and ammonium metavanadate (NH4VO3) as raw material and sodium dodecyl sulfate (SDS) as surfactant. The X-ray diffractometer (XRD) and the scanning electron microscopy (SEM) technology were used to characterize the Ce/BiVO4 nanocomposites. We investigated the photocatalytic activity of the as-prepared photocatalyst, and methyl orange was used as organic pollutant. The results show that the Ce/BiVO4 nanocomposite was a good photocatalyst under visible light. In 100 ml of 5 mg/L methylene orange solution, when the catalyst calcined at 673 K was 0.1 g, hydrogen peroxide was 0.5
Innovation for ascertaining genomic islands in PAO1 and PA14 of Pseudomonas aeruginosa
Lei Song,XueHong Zhang
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0598-0
Abstract: Based on three distinct traits of genomic islands, a novel approach was developed to search for and determine genomic islands in special strains. Two genomic islands in Pseudomonas aeruginosa PAO1 and 7 genomic islands in Pseudomonas aeruginosa PA14 were defined with this method. Among the 9 genomic islands, 4 islands had been characterized before, while the other 5 islands were initially determined. The insert sites of 6 genomic islands are tRNA sequences, direct repeats of PA14GI-3 are relative to tRNALeu, and direct repeats of PA14GI-2 are at the 3′ end of bifunctional GMP synthase/glutamine amidotransferase. Only direct repeats of PA14GI-4 are not clear. Among the 5 newly-found genomic islands, it was supposed that PA14GI-2 is a genomic island related to Hg2+ uptake, PA14GI-3 is a secretory activity genomic island, PA14GI-6 is a pathogenicity island, and functions of PA14GI-1 and PA14GI-5 are not clear. Finally, the tyrosine type integrases in PAO1GI-1, PA14GI-5 and PA14GI-7 were analyzed, and their binding and restriction sites were predicted.
Accurate localization and excision of genomic islands in four strains of Pseudomonas aeruginosa and Pseudomonas fluorescens
Lei Song,XueHong Zhang
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4410-6
Abstract: Mobile genomic islands (GIs) can be excised from the chromosome, then form a circular intermediate and be reintegrated into the chromosome by the GI internal integrase. Some mobile GIs can also be transferred into a new receptor cell by transformation, conjugation, or transduction. The action sites of the integrase are usually flanked direct repeats (DRs) of the GIs. Accurate localization of the flanking sequences is a precondition for determining the mobility of the GI. Mobile GIs are generally associated with transfer RNAs (tRNAs). Based on the correlation between flanking sequences and tRNA sequences, the flanking sequences of 11 putative mobile GIs in Pseudomonas aeruginosa PAO1, P. aeruginosa PA14, P. fluorescens Pf-5 and P. fluorescens Pf0-1 were identified. Among the 11 GIs, Pf0-1GI-1 is responsible for benzoate degradation. PAO1GI-1, Pf5GI-2, Pf5GI-3, and Pf5GI-4 were confirmed experimentally to be excised from a chromosome to form a circular intermediate. The action sites of the integrases are these GIs direct repeats. Due to distinct DRs, cutting sites for the internal integrase of PAO1GI-1, Pf5GI-2, Pf5GI-3 and Pf5GI-4 were determined outside the T-loop of the tRNAGly gene, outside the anticodon loop of the tRNASer gene and tRNALys gene, and at the asymmetric 3′-end of the tRNALeu gene, respectively. PAO1GI-1 and other mobile GIs may be transferred into many different strains that belong to different phyla because of the clear flanking sequences. This study describes basic information about the action sites of the integrases, assesses the mobility of GIs, and can help design and transfer mobile GIs to candidate strains.
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