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Search Results: 1 - 10 of 74152 matches for " Xiao-Xi Guo "
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Production of copolyesters of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoates by E. coli containing an optimized PHA synthase gene
Gao Xue,Yuan Xiao-Xi,Shi Zhen-Yu,Guo Ying-Ying
Microbial Cell Factories , 2012, DOI: 10.1186/1475-2859-11-130
Abstract: Background Microbial polyhydroxyalkanoates (PHA) are biopolyesters consisting of diverse monomers. PHA synthase PhaC2Ps cloned from Pseudomonas stutzeri 1317 is able to polymerize short-chain-length (scl) 3-hydroxybutyrate (3HB) monomers and medium-chain-length (mcl) 3-hydroxyalkanoates (3HA) with carbon chain lengths ranging from C6 to C12. However, the scl and mcl PHA production in Escherichia coli expressing PhaC2Ps is limited with very low PHA yield. Results To improve the production of PHA with a wide range of monomer compositions in E. coli, a series of optimization strategies were applied on the PHA synthase PhaC2Ps. Codon optimization of the gene and mRNA stabilization with a hairpin structure were conducted and the function of the optimized PHA synthase was tested in E. coli. The transcript was more stable after the hairpin structure was introduced, and western blot analysis showed that both codon optimization and hairpin introduction increased the protein expression level. Compared with the wild type PhaC2Ps, the optimized PhaC2Ps increased poly-3-hydroxybutyrate (PHB) production by approximately 16-fold to 30% of the cell dry weight. When grown on dodecanoate, the recombinant E. coli harboring the optimized gene phaC2PsO with a hairpin structure in the 5’ untranslated region was able to synthesize 4-fold more PHA consisting of 3HB and medium-chain-length 3HA compared to the recombinant harboring the wild type phaC2Ps. Conclusions The levels of both PHB and scl-mcl PHA in E. coli were significantly increased by series of optimization strategies applied on PHA synthase PhaC2Ps. These results indicate that strategies including codon optimization and mRNA stabilization are useful for heterologous PHA synthase expression and therefore enhance PHA production.
Ginsenoside Rh2 Induces Human Hepatoma Cell Apoptosisvia Bax/Bak Triggered Cytochrome C Release and Caspase-9/Caspase-8 Activation
Xiao-Xi Guo,Qiao Guo,Yang Li,Seung Ki Lee,Xue-Ning Wei,Ying-Hua Jin
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms131215523
Abstract: Ginsenoside Rh2 (G-Rh2) has been shown to induce apoptotic cell death in a variety of cancer cells. However, the details of the signal transduction cascade involved in G-Rh2-induced cell death is unclear. In this manuscript we elucidate the molecular mechanism of G-Rh2-induced apoptosis in human hepatoma SK-HEP-1 cells by demonstrating that G-Rh2 causes rapid and dramatic translocation of both Bak and Bax, which subsequently triggers mitochondrial cytochrome c release and consequent caspase activation. Interestingly, siRNA-based gene inactivation of caspase-8 effectively delays caspase-9 activation and apoptosis induced by G-Rh2, indicating that caspase-8 also plays an important role in the G-Rh2-induced apoptosis program. Taken together, our results indicate that G-Rh2 employs a multi pro-apoptotic pathway to execute cancer cell death, suggesting a potential role for G-Rh2 as a powerful chemotherapeutic agent.
Apoptosis is Induced in Cancer Cells via the Mitochondrial Pathway by the Novel Xylocydine-Derived Compound JRS-15
Chao Sun,Xiao-Xi Guo,Dan Zhu,Chuan Xiao,Xiao Bai,Yang Li,Zhuo Zhan,Xiang-Long Li,Zhi-Guang Song,Ying-Hua Jin
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14010850
Abstract: The novel compound JRS-15 was obtained through the chemical modification of xylocydine. JRS-15 exhibited much stronger cytotoxic and pro-apoptotic activity than its parent compound in various cancer cell lines, with IC 50 values in HeLa, HepG2, SK-HEP-1, PC-3M and A549 cells ranging from 12.42 to 28.25 μM. In addition, it is more potent for killing cancer than non-cancerous cells. Mechanistic studies showed that JRS-15 treatment arrested cell cycle at the G1/S phase, which further triggered the translocation of Bax and Bak to the mitochondria, resulting in mitochondrial membrane potential (MMP) depolarization and the subsequent release of cytochrome c and the second mitochondria-derived activator of caspase (Smac). The sequential activation of caspase-9 and caspase-3/7 and the cleavage of poly (ADP-ribose) polymerase (PARP) were observed following these mitochondrial events. Caspase-8, an initiator caspase that is required to activate the membrane receptor-mediated extrinsic apoptosis pathway was not activated in JRS-15-treated cells. Further analysis showed that the levels of the anti-apoptotic proteins Bcl-xL and XIAP were significantly reduced upon JRS-15 treatment. Furthermore, the caspase-9 inhibitor z-LEHD-fmk, the pan-caspase inhibitor z-VAD-fmk, and Bcl-xL or XIAP overexpression all effectively prevented JRS-15-induced apoptosis. Taken together, these results indicate that JRS-15 induces cancer cell apoptosis by regulating multiple apoptosis-related proteins, and this compound may therefore be a good candidate reagent for anticancer therapy.
Application of starch adhesive in organic compound fertilizer granulation

LI Yan-Ming,LIU Xiao-Xi,LI Guo-Xue,WEI Yuan,
,刘晓霞,李国学,魏 远

中国生态农业学报 , 2007,
Abstract: Although mineral binder bonds are widely used in organic compound fertilizers,their inevitable shortcomings limit their application in the organic compound fertilizers.Direct application of crude cornstarch(CK2) adhesive is unfit for granulation of organic compound fertilizers.But the use of liquid adhesive A and dry powder adhesive B(both obtained by the modification of cornstarch)as granulation adhesive in organic compound fertilizer granulation produces granules with quality exceeding Chinese and International Standards.Both two adhesives have granulation percentage greater than 93%,return products less than attapulgites',and used level under 1%.The granules resist crushing forces greater than 10N,and maintain a 100% integrity after immersed in deionized water for 24 hours.Modified cornstarch adhesives practically substitute inorganic binders.Adhesive A and B can be used as granulation adhesive for high nutrient-rich organic compound fertilizers.
New low illumination color image enhancement algorithm

LI Xiao-xi,LI Cheng-guo,ZOU Jian-hu,HAN Xue-mei,

计算机应用研究 , 2011,
Abstract: 为了增强彩色图像而不引起色彩失真,在HSV颜色空间中保持色相不变,提出了采用分段对数变换增强饱和度结合在多尺度Retinex算法的基础上,采用边缘保持增强色调的低照度彩色图像增强算法。实验结果表明,该方法在保持图像色相和图像边缘的情况下,显著改善了图像的视觉效果,提高了图像的亮度和对比度。25幅低照度图像的平均亮度、标准偏差和对比度分别提高了94.95%、20.93%和29.88%,相对于带色彩恢复的多尺度Retinex算法的熵和对比度增量分别提高了7.34%和151.51%,效果优于Retinex算法。
Isopropyl 4-chloro-3,5-dinitrobenzoate
Xiao-Xi Tai,Jing Sun
Acta Crystallographica Section E , 2010, DOI: 10.1107/s160053681004359x
Abstract: In the title compound, C10H9ClN2O6, the two nitro groups and the ester group are oriented with respect to the benzene ring at dihedral angles of 49.42 (13)/87.61 (13) and 9.10 (10)°, respectively. In the crystal structure, a weak C—H...O interaction is present. A short Cl...O contact of 2.972 (2) is also observed in the crystal structure.
Discrete Particle Swarm Optimization Algorithm for the Routing of VLSI Circuit

LIU Geng-geng,WANG Xiao-xi,CHEN Guo-long,GUO Wen-zhong,WANG Shao-ling,

计算机科学 , 2010,
Abstract: Rectilinear Stciner Minimal Trec is one of the key problems in the routing of Very I_argc Scare Integration and a typical NP-complete problem. To solve the rectilinear Steiner minimal tree with rectangular obstacles(RSMTRO)problem effectivcly,an improved discrete particle swarm optimization(IDPSO ) algorithm was proposed Considering existence of obstacles, the penalty-based fitness function was designed. The principles of mutation and crossover operator in genetic algorithm were incorporated into the proposed PSO algorithm to achieve better diversity, and the scope of the particle optimization was appropriately expanded. Simulation results show that IDPSO algorithm can efficiently provide RSMTRO solution with good quality and converges more efficiently and rapidly than genetic algorithm.
A new diphenyl ether from an endolichenic fungal strain, Aspergillus sp.

HUANG Yuan-Fan,LI Xiao-Xi,CHEN Guo-Dong,GAO Hao,GUO Liang-Dong,YAO Xin-Sheng,

菌物学报 , 2012,
Abstract: One new diphenyl ether (1) together with one known analogue (2) were isolated from the fermented extract of an endolichenic fungal strain Aspergillus sp. (No. 16-20-8-1) by means of silica gel, ODS, Sephadex LH-20 column chromatography and preparative HPLC. Their structures were elucidated as 2-isopentenyldiorcinol (1) and diorcinol (2) by MS and NMR data analysis.
Hyperproduction of poly(4-hydroxybutyrate) from glucose by recombinant Escherichia coli
Xiao-Yun Zhou, Xiao-Xi Yuan, Zhen-Yu Shi, De-Chuan Meng, Wen-Jun Jiang, Lin-Ping Wu, Jin-Chun Chen, Guo-Qiang Chen
Microbial Cell Factories , 2012, DOI: 10.1186/1475-2859-11-54
Abstract: Recombinant Escherichia coli strain was constructed to achieve hyperproduction of poly(4-hydroxybutyrate) [poly(4HB)] using glucose as a sole carbon source. An engineering pathway was established in E. coli containing genes encoding succinate degradation of Clostridium kluyveri and PHB synthase of Ralstonia eutropha. Native succinate semialdehyde dehydrogenase genes sad and gabD in E. coli were both inactivated to enhance the carbon flux to poly(4HB) biosynthesis. Four PHA binding proteins (PhaP or phasins) including PhaP1, PhaP2, PhaP3 and PhaP4 from R. eutropha were heterologously expressed in the recombinant E. coli, respectively, leading to different levels of improvement in poly(4HB) production. Among them PhaP1 exhibited the highest capability for enhanced polymer synthesis. The recombinant E. coli produced 5.5 g?L-1 cell dry weight containing 35.4% poly(4HB) using glucose as a sole carbon source in a 48 h shake flask growth. In a 6-L fermentor study, 11.5 g?L-1 cell dry weight containing 68.2% poly(4HB) was obtained after 52 h of cultivation. This was the highest poly(4HB) yield using glucose as a sole carbon source reported so far. Poly(4HB) was structurally confirmed by gas chromatographic (GC) as well as 1H and 13C NMR studies.Significant level of poly(4HB) biosynthesis from glucose can be achieved in sad and gabD genes deficient strain of E. coli JM109 harboring an engineering pathway encoding succinate degradation genes and PHB synthase gene, together with expression of four PHA binding proteins PhaP or phasins, respectively. Over 68% poly(4HB) was produced in a fed-batch fermentation process, demonstrating the feasibility for enhanced poly(4HB) production using the recombinant strain for future cost effective commercial development.
Public Opinion Analysis System for WWW-Based Digital Media Content

WANG Xiao-Yan,LIANG Jin-Chun,GUO Xiao-Xi,YAO Ying-Ying,WANG Ying,

计算机系统应用 , 2011,
Abstract: The rapid developing Internet has become an important reflection of public opinions.It has been an urgent problem to be solved how to analyze and monitor public opinions in digital media and on Internet,and how to timely and effectively spot all kinds false information harmful to social security,in order to promote the healthy development of information security and content supervision.This paper proposes a www-based digital media content public opinion analysis model.A digital media content public opinion ...
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