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Search Results: 1 - 10 of 59066 matches for " Shulin Yang "
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Impact of Leucine 278 Residue on Fatty Acid Length Specificity of Candida antarctica Lipase B  [PDF]
Fanghua Wang, Shulin Hou, Qian Wang, Pu Wang, Jinsong Liu, Bo Yang, Yonghua Wang
Advances in Microbiology (AiM) , 2015, DOI: 10.4236/aim.2015.57050
Abstract: Structural analysis of Candida antarctica lipase B (CALB) indicates that side chain of leucine at 278 site lies above the entrance of the catalytic pocket, which prognosticates its potential role on substrate specificity of the enzyme. To verify this presumption, shortened side chain of glycine or proline was rational designed and mutants were constructed by site-directed mutagenesis method. The colorimetric assay using p-nitrophenyl esters of fatty acids with various chain-lengths was used to study the substrate preference of lipases. Results indicated that L278G or L278P mutations both induced the drift of substrate specificity of CALB from p-nitrophenyl caprylate (pNP-C8) to longer carbon chain length of p-nitrophenyl caprate (pNP-C10). Meanwhile, Vmax value of two mutants to pNP-C10 was both higher than that of wild-type. Docking results also indicated that shortened side chain of glycine or proline residues substitution at this site could get rid of the space block present above the catalytic pocket, and made longer chain substrate (pNP-C10) enter into the catalytic pocket easier. The modulation of specificity observed allowed for building substrate binding model and opened new possibilities for designing ligand specific lipases.
Jianzhang Wu,Li Zhang,Jing Wang,Shulin Yang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809041877
Abstract: In the title compound, C18H18O4, a derivative of biologically active chalcones, the dihedral angle between the two rings is 7.43 (7)°. The molecule adopts an E configuration about the central olefinic bonds. In the crystal, there are no strong interactions between the molecules.
Jianzhang Wu,Junyan Qiu,Xiaokai Wu,Shulin Yang
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536811053001
Abstract: In the title chalcone derivative, C20H22O6, the dihedral angle between the mean planes of the benzene rings is 15.77 (6)°. The H atoms of the central C=C double bond are in a trans configuration. There are a number of C—H...O interactions and a C—H...π interaction present in the crystal structure.
Identification and analysis of pig chimeric mRNAs using RNA sequencing data
Ma Lei,Yang Shulin,Zhao Weiming,Tang Zhonglin
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-429
Abstract: Background Gene fusion is ubiquitous over the course of evolution. It is expected to increase the diversity and complexity of transcriptomes and proteomes through chimeric sequence segments or altered regulation. However, chimeric mRNAs in pigs remain unclear. Here we identified some chimeric mRNAs in pigs and analyzed the expression of them across individuals and breeds using RNA-sequencing data. Results The present study identified 669 putative chimeric mRNAs in pigs, of which 251 chimeric candidates were detected in a set of RNA-sequencing data. The 618 candidates had clear trans-splicing sites, 537 of which obeyed the canonical GU-AG splice rule. Only two putative pig chimera variants whose fusion junction was overlapped with that of a known human chimeric mRNA were found. A set of unique chimeric events were considered middle variances in the expression across individuals and breeds, and revealed non-significant variance between sexes. Furthermore, the genomic region of the 5′ partner gene shares a similar DNA sequence with that of the 3′ partner gene for 458 putative chimeric mRNAs. The 81 of those shared DNA sequences significantly matched the known DNA-binding motifs in the JASPAR CORE database. Four DNA motifs shared in parental genomic regions had significant similarity with known human CTCF binding sites. Conclusions The present study provided detailed information on some pig chimeric mRNAs. We proposed a model that trans-acting factors, such as CTCF, induced the spatial organisation of parental genes to the same transcriptional factory so that parental genes were coordinatively transcribed to give birth to chimeric mRNAs.
Phase Transition and Optical Properties for Ultrathin KNbO3 Nanowires
Shulin Yang,Yongming Hu,Shengfu Wang,Haoshuang Gu,Yu Wang
Advances in Condensed Matter Physics , 2013, DOI: 10.1155/2013/567420
Abstract: Fascicular KNbO3 nanowires with tetragonal perovskite structures and ultrasmall diameters are synthesized by hydrothermal route at about 150°C for 24 hours. The concentrations of medium alkalinity have influenced phase structures and the final morphologies of the products significantly by modifying the conditions in process. The as-prepared KNbO3 nanowires exhibit three phase transitions at about 343, 454.7, and 623?K as the temperature increases from 250 to 700?K. The band gap is about 3.78?eV for KNbO3 nanowires. Photoluminescence study at room temperature reveals two visible light emission bands peaking at ~551 and 597?nm, respectively, which may be due to the oxygen vacancies, site niobium (occupy the location of Nb), and antisite niobium (occupy the location of K) in KNbO3 nanowires. 1. Introduction Perovskite-type metallic oxides make a family of materials that share a common crystal structure, analogy to that of the natural crystal calcium titanate, yet exhibit a broad range of interesting physical properties [1]. With the advances in science and technology of integrated ferroelectrics, the size-dependent ferroelectric behaviors become crucial due to the dimensional confinement or the size of ferroelectrics decreasing [2]. 1D nanostructure of ferroelectric materials, such as nanorods, nanowires, and nanotubes, have attracted great attention due to their promising applications, such as miniaturized piezoelectric actuators, medical imaging detectors, and even ferroelectric memories [3, 4]. In recent years, the size-dependent physical properties, such as phase transition, polarizations, and energy band, in ferroelectric nanowires have been evaluated systematically. For instance, Naumov and Fu revealed that both the Curie temperature and the polarization of Pb(Zr0.5Ti0.5)O3 nanowire decreased with the reducing diameter [5]. Spanier et al. reported that phase transition temperature of BaTiO3 nanowires fell below room temperature as the diameter was ~3?nm [6]. Geneste et al. found that the ferroelectric properties of BaTiO3 nanowire vanished when the diameter was less than 1.2?nm according to the first principle calculation [7]. However, Morozovska et al. reported that the Curie temperature of ferroelectric nanorods/nanowires could be higher than that of bulk materials from a direct variational method [8]. In addition, the author revealed that there was a blue-green emission for PbTiO3 nanowires (with diameters of 10~20?nm) both the oxygen vacancies and lead-oxygen vacancy centers may be responsible for this phenomenon [9]. Despite very promising
CRABP2 Promotes Myoblast Differentiation and Is Modulated by the Transcription Factors MyoD and Sp1 in C2C12 Cells
Jing Yuan, Zhonglin Tang, Shulin Yang, Kui Li
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055479
Abstract: Cellular retinoic acid binding protein 2 (CRABP2), a member of a family of specific carrier proteins for Vitamin A, belongs to a family of small cytosolic lipid binding proteins. Our previous study suggested that CRABP2 was involved in skeletal muscle development; however, the molecular function and regulatory mechanism of CRABP2 in myogenesis remained unclear. In this study, we found that the expression of the CRABP2 gene was upregulated during C2C12 differentiation. An over-expression assay revealed that CRABP2 promotes myogenic transformation by regulating the cell cycle during C2C12 differentiation. The region from ?459 to ?4 bp was identified as the core promoter and contains a TATA box, a GC box and binding sites for the transcription factors MyoD and Sp1. Over-expression, site-directed mutagenesis and EMSA assays indicated that the transcription factors MyoD and Sp1 regulate CRABP2 expression and promote myoblast differentiation in C2C12 cells.
Forecasting New Product Diffusion Using Grey Time-Delayed Verhulst Model
Yuhong Wang,Shulin Yang,Wuyong Qian,Xiaozhong Li
Journal of Applied Mathematics , 2013, DOI: 10.1155/2013/625028
Abstract: Taking account of the time-delayed phenomenon in diffusion of new products, we propose the time-delayed Verhulst model and then establish a grey time-delayed Verhulst model using the method of grey differential equations. The related parameter packets of this novel model are obtained under the rule of ordinary least squares (OLS). The results show that the traditional grey Verhulst model is a special example of grey time-delayed Verhulst model which can reflect the time-delayed information effectively. A practical example of market diffusion shows that the modeling accuracy is remarkably improved by using the grey time-delayed Verhulst model presented in this paper. 1. Introduction When a new type of products enters the related market, managers want to know the sales and consumer acceptance rate of the new product in the market. And this information is very important for them to make marketing plans, production plans, and even the developing strategies of the company. We first introduce two types of classical models for market diffusion, analyze the pros and cons, and then propose the problem which will be solved in this paper. Assume that is the cumulative number using a new product. According to the Malthus theory, we know that the incremental purchase number is proportional to . Thus, we have the following model: where is the growth rate of purchasing. If , obeys the law of exponential growth. However, the market demand for new products is limited. The growth rate of purchasing any product will not be an exponential trend when it reaches a certain penetration rate. Considering the restriction of market demand for new products, Malthus model must be improved. Assume that is the total number of potential consumers; the purchase growth rate increases with the decrease of . When , the purchase growth rate tends to be 0. Thus, we have the following improved model: Let and , and (2) could be written as Equation (3) is the Verhulst model proposed by German mathematician Verhulst in 1937. Raw data are required to be an approximate S-shape for establishing traditional Verhulst model, or ineffective. Professor Deng greyed the traditional Verhulst model based on the concepts and principles of grey differential equation and obtained the following grey Verhulst model [1]: The grey Verhulst model, which is a first-order one-variable grey differential equation and also a time series model. The original data vary with time, as do their randomness characteristics. It is one of the basic models of Grey system forecasting and control. Rather than relying on its
A Modified Discrete-Time Jacobi Waveform Relaxation Iteration  [PDF]
Yong Liu, Shulin Wu
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.24064
Abstract: In this paper, we investigate an accelerated version of the discrete-time Jacobi waveform relaxation iteration method. Based on the well known Chebyshev polynomial theory, we show that significant speed up can be achieved by taking linear combinations of earlier iterates. The convergence and convergence speed of the new iterative method are presented and it is shown that the convergence speed of the new iterative method is sharper than that of the Jacobi method but blunter than that of the optimal SOR method. Moreover, at every iteration the new iterative method needs almost equal computation work and memory storage with the Jacobi method, and more important it can completely exploit the particular advantages of the Jacobi method in the sense of parallelism. We validate our theoretical conclusions with numerical experiments.
Low Concentrations of o,p’-DDT Inhibit Gene Expression and Prostaglandin Synthesis by Estrogen Receptor-Independent Mechanism in Rat Ovarian Cells
Jing Liu, Meirong Zhao, Shulin Zhuang, Yan Yang, Ye Yang, Weiping Liu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049916
Abstract: o,p’-DDT is an infamous xenoestrogen as well as a ubiquitous and persistent pollutant. Biomonitoring studies show that women have been internally exposed to o,p’-DDT at range of 0.3–500 ng/g (8.46×10?10 M?1.41×10?6 M) in blood and other tissues. However, very limited studies have investigated the biological effects and mechanism(s) of o,p’-DDT at levels equal to or lower than current exposure levels in human. In this study, using primary cultures of rat ovarian granulosa cells, we determined that very low doses of o,p’-DDT (10?12?10?8 M) suppressed the expression of ovarian genes and production of prostaglandin E2 (PGE2). In vivo experiments consistently demonstrated that o,p’-DDT at 0.5–1 mg/kg inhibited the gene expression and PGE2 levels in rat ovary. The surprising results from the receptor inhibitors studies showed that these inhibitory effects were exerted independently of either classical estrogen receptors (ERs) or G protein-coupled receptor 30 (GPR30). Instead, o,p’-DDT altered gene expression or hormone action via inhibiting the activation of protein kinase A (PKA), rather than protein kinase C (PKC). We further revealed that o,p’-DDT directly interfered with the PKA catalytic subunit. Our novel findings support the hypothesis that exposure to low concentrations of o,p’-DDT alters gene expression and hormone synthesis through signaling mediators beyond receptor binding, and imply that the current exposure levels of o,p’-DDT observed in the population likely poses a health risk to female reproduction.
Optimal Production and Biochemical Properties of a Lipase from Candida albicans
Dongming Lan,Shulin Hou,Ning Yang,Chris Whiteley,Bo Yang,Yonghua Wang
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12107216
Abstract: Lipases from microorganisms have multi-faceted properties and play an important role in ever-growing modern biotechnology and, consequently, it is of great significance to develop new ones. In the present work, a lipase gene from Candida albicans (CaLIP10) was cloned and two non-unusual CUG serine codons were mutated into universal codons, and its expression in Pichia pastoris performed optimally, as shown by response surface methodology. Optimal conditions were: initial pH of culture 6.86, temperature 25.53 °C, 3.48% of glucose and 1.32% of yeast extract. The corresponding maximal lipolytic activity of CaLIP10 was 8.06 U/mL. The purified CaLIP10 showed maximal activity at pH 8.0 and 25 °C, and a good resistance to non-ionic surfactants and polar organic solvent was noticed. CaLIP10 could effectively hydrolyze coconut oil, but exhibited no obvious preference to the fatty acids with different carbon length, and diacylglycerol was accumulated in the reaction products, suggesting that CaLIP10 is a potential lipase for the oil industry.
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