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Expression of Recombinant Chinese Bovine Enterokinase Catalytic Subunit in P. pastoris and Its Purification and Characterization

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Acta Biochimica et Biophysica Sinica 2004年第7期36卷 513-517页

作者： Lei FANG, Qi-Ming SUN, and Zi-Chun HUA*The state key laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, China The state key laboratory of Pharmaceutical Biotechnology Nanjing University Nanjing 210093 China

Enterokinase is a tool protease widely utilized in the cleavage of recombinant fusion proteins. cDNA encoding the catalytic subunit of Chinese bovine enterokinase (EKL) was amplified by PCR and then fused to the 3′ end of prepro secretion signal peptide gene of α-mating factor from Saccharomyces cerevisiae to get the α-MF signal-EKL-His6 encoding gene by PCR. Then the whole coding sequence was cloned into the integrative plasmid pAO815 under the control of a methanol-inducible promoter and transformed GS115 methylotrophic strain of Pichia pastoris. Secreted expression of recombinant EKL-His6 was attained by methanol induction and its molecular weight is 43 kD. Because of the existence of His6-tag, EKL-His6 was easily purified from P. pastoris fermentation supernatant by using Ni2+ affinity chromatography and the yield is 5.4 mg per liter of fermentation culture. This purified EKL-His6 demonstrates excellent cleavage activity towards fusion protein containing EK cleavage site.

关键词： recombinant enterokinase secreted expression Ni2+ affinity chromatography fusion protein cleavage

Wide/narrow azimuth acquisition footprints and their effects on seismic imaging

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Petroleum Science 2008年第4期5卷 308-313页

作者： Di Bangrang Xu Xiucang Wei Jianxin key laboratory of CNPC Geophysical Exploration China University of Petroleum Beijing 102249 China state key laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China key laboratory of Earth Prospecting and Information Technology China University of Petroleum Beijing 102249 China

Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition footprints has become a hot spot. In partnership with the Dagang Oilfield, we used the channel sand body seismic physical model to study the characteristics of wide/narrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging. In addition, the footprints caused by data processing of the normal moveout offset （NMO） stretching aberration were discussed. These footprints are located only in the shallow or middle layer in the time slice, and possibly affect the imaging of shallow target layers, and have no influence on deep target imaging. Seismic physical modeling has its advantages in the study of acquisition footprints.

关键词： Wide/narrow azimuth geometry acquisition footprint stretching aberration time slice seismic imaging

state space approach for joint estimation of activity and attenuation map from PET emission sinograms

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Progress in Natural Science:Materials International 2007年第5期17卷 614-617页

作者： Liu Huafeng , You Hongshun and Shi Pengcheng (state key laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China College of Biomedical Engineering, Southern medical University, Guangzhou 510015, China) [a]state key laboratory of Modern Optical Instrumentation Zhejiang University Hangzhou China [b]College of Biomedical Engineering Southern Medical University Guangzhou China

Quantitative estimation of radioactivity map has important clinical implications for better diagnosis and understanding of cancers. Although attenuation map and activity map are usually treated sequentially, they can obviously benefit a great deal when the transmission data is missing. In this paper, we propose a novel scheme of simultaneously solving for attenuation map and activity distribution from emission sinograms. Our strategy combines the measurement model of PET, and the attenuation parameters are treated as random variables with known prior statistics. After the conversion to state space representation, the extended Kalman filtering procedures are adopted to linearize the equations and to provide the joint estimates in an approximate optimal sense. Experiments have been performed on both synthetic data to illustrate its abilities and benefits.

关键词： positron emission tomography attenuation correction state space methods.

In situ synthesis of DNA micro-arrays using typography technique

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Science China Chemistry 2007年第1期50卷 75-83页

作者： TANG JianXin 1,2 ,HE NongYue 1,2,3 &LI Song 1 1state key laboratory of Bioelectronics,Southeast University,Nanjing 210096,China 2key laboratory of Green Packaging and Application of Biological Nanotechnology of Hunan Province,Hunan University of Tech- nology,Zhuzhou 412008,China 3Zhongshan Huoju Polytechnic,Zhongshan 528436,China 1. state key laboratory of Bioelectronics Southeast University Nanjing 210096 China 2. key laboratory of Green Packaging and Application of Biological Nanotechnology of Hunan Province Hunan University of Technology Zhuzhou 412008 China 3. Zhongshan Huoju Polytechnic Zhongshan 528436 China

A novel typography technique was developed to in situ synthesize oligonucleotide arrays on glass slide,which has the celerity,high spatial resolution,lower cost,reliable operation,and high synthetic *** principle and process of the typography technique for fabricating gene-chips have been described in detail.A suit of poly(terafluoroethylene)devices for synthesizing oligonucleotide arrays were designed and prepared,and the fiber tubes with a number of nano-or micron-channels were em- *** oligonucleotide arrays of 16 and 160 features with four different probes were synthesized using the typography *** four specific oligonucleotide probes including the matched and the mismatched by the fluorescent target sequence gave obviously different hybridization fluorescent *** was indicated that the gene-chip fabricated by the typography method could be used to rapidly screen single-nucleotide polymorphisms(SNP)and to detect mutations.

关键词： typography oligonucleotide in situ synthesis DNA microarrays

A patch-clamp study on human sperm Cl^- channel reassembled into giant liposome

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Asian Journal of Andrology 2001年第3期3卷 185-191页

作者： Jun-Ping BAI Yu-Liang SHI key laboratory of neurobiology,Intitute of Physiology,Shanghai Institutes for Biological Sciences,Chinese Academy of Science, Shanghai 200031,China key laboratory of neurobiology Institute of Physiology Shanghai Institutes for Biological SciencesChinese Academy of Sciences Shanghai 200031 China

Aim: To record the single-channel currents and characterize the electrophysiological properties of the Cl^- channels inhuman sperm membrane. Methods: The membrane proteins extracted from the human sperm were reassembled intoliposome bilayer, and the liposomes were fused into giant liposomes with a diameter more than 10μm by dehydration-rehydration procedure. The giant liposomes were used to study the Cl^- channel activities by patch-clamp ***: By patch clamping the giant liposome in an asymmetric NMDG (N-methyl-D-glucamine)-Cl (bath 100//pipette 200 mmol/L) solution system, three kinds of single-channel events with unit conductances of (74.1 ± 8.3) pS,(117.0±5.7) pS and (144.7±4.5) pS, respectively, were detected. Their activities were voltage-dependent and allwere blocked by SITS (4-acetamido-4'-isothiocyanato-stilbene-2', 2'-disulfonic acid) in a concentration-dependentmanner. By constructing the open and close dwell time distribution histograms and then fitting them with exponentialfunction, two time constants were obtained in both the open and the close states. The burst activity and conductancesubstate of the channels were observed. Conclusion; There exist three kinds of Cl^- channels with different conduc-tance in human sperm membrane at least. (Asian J Androl 2001 Sep; 3: 185 - 191)

关键词： Cl^-channel giant liposome patch clamp human sperm membrane ion channel reassembly

On power allocation for a cognitive radio network with hybrid spectrum sharing

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Science China(Information Sciences) 2011年第11期54卷 2425-2434页

作者： ZHANG Jing 1,2,3 & ZHU HongBo 1 1 key laboratory of Wireless Communications of Jiangsu Province,Nanjing University of Posts & Telecommunications,Nanjing 210003,China 2 College of Electronic Science & Engineering,Nanjing University of Posts & Telecommunications,Nanjing 210003,China 3 state key laboratory of Millimeter Waves,Nanjing 210096,China 1. key laboratory of Wireless Communications of Jiangsu Province Nanjing University of Posts & Telecommunications Nanjing 210003 China2. College of Electronic Science & Engineering Nanjing University of Posts & Telecommunications Nanjing 210003 China3. State Key Laboratory of Millimeter Waves Nanjing 210096 China

In this study we propose a hybrid spectrum sharing scheme based on power control by combining Overlay with Underlay schemes,to improve radio spectrum *** the scheme,the secondary users dynamically switch their operational states between Overlay and Underlay according to the spectrum *** the dynamics of the primary network is first modeled with a discrete-state Markov process to find the time fraction of secondary users in the Overlay state and that in the Underlay state,which leads to the capacity model of the hybrid spectrum sharing *** the criterion of maximizing capacity,the power allocation of the cognitive network is researched and the optimum power allocation for secondary users is *** a result,the maximum achievable capacity of the cognitive network is *** are given to prove the analysis *** and simulated results indicate that hybrid spectrum sharing based on power control provides a higher capacity than single Overlay and Underlay systems for the cognitive network,i.e.,hybrid spectrum sharing can further improve radio spectrum efficiency.

关键词： cognitive radio network hybrid spectrum sharing primary network dynamics power allocation achievable capacity

Research progress in Shigella in the postgenomic era

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Science China(Life Sciences) 2010年第11期53卷 1284-1290页

作者： PENG JunPing, YANG Jian & JIN Qi state key laboratory for Molecular Virology and Genetic Engineering, Institute of Pathogen Biology,Chinese Academy of medical Sciences & Peking Union medical College, Beijing 100176, China 1. state key laboratory for Molecular Virology and Genetic Engineering Institute of Pathogen Biology Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100176 China

Gram-negative,facultative intracellular anaerobes of the genus Shigella,the principal etiologic agents of shigellosis,continue to pose a threat to public health. Shigellosis causes 1.1 million deaths with over 164 million annual cases. The Shigella spp. can be divided into four serogroups:Shigella dysenteriae,Shigella flexneri, Shigella boydii and Shigella sonnei. The completion of seven Shigella genome sequences of representative strains from each of the Shigella species has introduced an era of whole-genome *** paper reviews contemporary understanding of genomics,transcriptomics,proteomics and the structural biology of Shigella.

关键词： Shigella genomics transcriptomics proteomics structural biology

Cloning and characterization of an up-regulated GA 20-oxidase gene in hybrid maize

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Progress in Natural Science:Materials International 2009年第2期19卷 161-166页

作者： Jinkun Du,Yingyin Yao,Zhongfu Ni,Qixin Sun Department of Plant Genetics & Breeding and state key laboratory for Agrobiotechnology,key laboratory of Crop Genomics and Genetic Improvement,Ministry of Agriculture/Beijing key laboratory of Crop Genetic Improvement,China Agricultural University,Beijing 100094,China [a]Department of Plant Genetics & Breeding and state key laboratory for Agrobiotechnology Key Laboratory of Crop Genomics and Genetic Improvement Ministry of Agriculture/Beijing Key Laboratory of Crop Genetic Improvement China Agricultural University Beijing 100094 China

Previous studies revealed that GA content and metabolism are positively correlated with a faster shoot growth rate of hybrid,and recently,genes participating in both GA biosynthesis and GA response pathways were also found to be differentially expressed between wheat hybrid and its parental inbreds. In this study,an up-regulated GA 20-oxidase gene in a maize hybrid,designated ZmGA20,was cloned. ZmGA20 contains an open reading frame (ORF) encoding 391 amino acid residues. BLASTX searches in GenBank revealed that the ZmGA20 is homologous to the sequences of GA20ox proteins from different species,and analysis also indicated that ZmGA20 had typical features of GA 20-oxidase proteins,including a "LPWKET" sequence. Semi-quantitative RT-PCR analysis showed that ZmGA20 was expressed in different tissues and/or organs. The expression level of ZmGA20 in the hybrid was higher than that in two parents (in roots,leaves,stems and embryo,and ears). The abundance of ZmGA20 transcript was equal to that of the highly expressed parents,which provided molecular evidence for the observed GA content heterosis in maize hybrids.

关键词： GA 20-oxidase Gene expression Maize Heterosis

A NEW WELL TEST MODEL FOR STRESS-SENSITIVE AND RADIALLY HETEROGENEOUS DUAL-POROSITY RESERVOIRS WITH NON-UNIFORM THICKNESSES

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Journal of Hydrodynamics 2011年第6期23卷 759-766页

作者： ZHANG Lie-hui, GUO Jing-jing, LIU Qi-guo state key laboratory of Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China state key laboratory of Reservoir Geology and Exploitation Southwest Petroleum University Chengdu 610500 China

This article presents a new well test model for stress-sensitive composite dual-porosity reservoirs based on the concept of permeability modulus, where the rock and fluid properties as well as the formation thickness vary in the radial direction. An analytical solution in the Laplace space for the pressure-transient behavior for a line-source, constant-rate well of this type of reservoir is obtained with the Laplace transformation and the perturbation technique. The pressure and its derivative in the reservoir and the effects of relevant parameters on the pressure-transient response are obtained. The model as well as the corresponding type curves may be used in predicting the production performance or analyzing the production data for this type of reservoir.

关键词： non-uniform thickness stress-sensitive composite dual-porosity well test model type curve