用差分方程模型模拟北京2003年SARS疫情

根据北京2003年SARS疫情发展的实际情况,利用差分方程建立模拟北京疫情发展过程(2003年3月20日至7月14日)的数学模型．建立主要由模拟值与实际统计值之差的平方和构成的目标函数．最后利用Gauss-Newton最优化方法,对模型中参数进行估计．     

人诺如病毒衣壳蛋白的密码子优化及在昆虫细胞中的表达

诺如病毒是当前在中国引起腹泻的主要人类杯状病毒,其中GGII4、GGII1和GGII3等为主要的流行遗传型。为了提高诺如病毒衣壳蛋白的表达量,我们将其编码基因按杆状病毒喜用密码子进行了优化设计和人工合成。以杆状病毒为载体,在昆虫细胞Sf9中对密码子优化后的诺如病毒GGII1、GGII3、GGII4和GGII7型衣壳蛋白基因进行了表达。结果显示,与野生型基因相比,经过密码子优化的基因在昆虫细胞中的表达水平得到明显提高,并可装配成病毒样颗粒。重组杆状病毒感染Sf9细胞72h表达量达到高峰。这些结果的取得,为我国人杯状病毒免疫学检测试剂和疫苗的开发打下了基础。     

基于IPSO-BP神经网络模型的山东省碳排放预测及生态经济分析

在低碳经济发展背景下,针对山东省碳排放数据更新迟缓、以往预测模型难以满足现实需求的问题,统计相关数据,根据政府间气候变化专门委员会(IPCC)推荐方法测算山东省2000—2017年碳排放量和排放强度,并借助脱钩分析、碳承载力和碳赤字探究碳排放的动态变化趋势;基于5项最重要的碳排放影响因素,建立改进的粒子群算法(IPSO...     

乳酸乳球菌Nisin抗性基因nisI的克隆及作为筛选标记的研究

摘要：【目的】为了优化LJ1菌株的培养条件使之产生高活性的胞外褐藻胶裂解酶。【方法】通过富集培养技术从海带筛选到一株褐藻胶裂解酶产生菌LJ1, 依据表型特征、脂肪酸组成分析及16S rRNA基因序列分析对该菌株进行鉴定。通过单因子和正交试验对LJ1 菌株产胞外褐藻胶裂解酶的培养条件进行了优化。【结果】LJ1菌株属于假交替单胞菌属（Pseudoalteromonas）。该菌株产酶的最佳培养基组成为：褐藻胶3 g/L、(NH4)2SO4 3 g/L、NaCl 20 g/L、KH2PO4 0.1 g/L、CaCl2 0.1 g/L;最佳培养条件为：250 mL三角烧瓶中装液量25 mL、接种量3%、摇瓶转速150 r/min、pH7.5、培养温度为28℃、培养时间为24 h。LJ1菌株所产褐藻胶裂解酶的最适温度为40℃,最适pH7.6,最适NaCl浓度为0.3 mol/L。1 mol/L金属离子Mg2+对酶活力有明显的促进作用,而Co2+ 和Zn2+对酶活力有较强的抑制作用。【结论】LJ1菌株是Pseudoalteromonas 新的胞外褐藻胶裂解酶产生菌,在最佳培养条件下,该菌株的酶活力提高了66%。     

优化的复合自动诱导培养基（CAI-4）对外源蛋白在大肠杆菌中 表达的影响

[目的]原核表达系统是目前最为广泛使用的一种外源蛋白表达系统。在利用原核表达系统表达目的蛋白的过程中,可溶性外源蛋白的产量是决定成本和效率的决定性因素。[方法]本项研究中利用本实验室构建的7种不同的重组质粒(-1、p-2、p-3、p-4、p-5、p-6、p-7),检测其在复合自动诱导培养基中的表达情况,评价哪一种培养基更适合于外源蛋白的表达,提高目的蛋白的产量。[结果]结果显示,这7种重组蛋白在复合自动诱导培养基的表达量是普通LB培养基的4~8倍;并在此基础上,对复合培养基的成份进行进一步优化,形成了一种优化培养基(改良培养基-4),P-1、P-2、P-3这3种融合蛋白在这种改良培养基中的表达量比优化前提高了至少2倍。     

Chiral separation of phospine‐containing α‐amino acid derivatives using two complementary cellulosic stationary phases in supercritical fluid chromatography

Enantiomeric separations of six amino‐acid derivatives have been studied using packed‐column supercritical fluid chromatography with two polysaccharide‐based enantioselective stationary phases: cellulose tris(3,5‐dimethylphenylcarbamate) and cellulose tris(3‐chloro‐4‐methylphenylcarbamate) (Lux Cellulose‐1 and ‐2). The effect of analyte structure on retention and separation was studied. Varied mobile phase compositions were investigated: alcohol modifier percentage was increased from 3 to 40% but smaller amounts were most effective in separating these compounds. Besides, ethanol was preferred to methanol or isopropanol as it proved to be a good compromise to achieve sufficient resolution in a reasonable analysis time. Moreover, a carbon dioxide‐ethanol mixture allows performing analyses in safe and green conditions. The effect of temperature at constant mobile phase composition was explored between 10 and 40°C. In most cases, increasing the temperature improved the chiral separation, up to an optimum temperature. The results are discussed in line with the structure variation of the racemic derivatives analyzed and the two columns are compared. The two columns were shown to provide complementary selectivities for the investigated solutes: whereas Lux 1 provided separation for five of the six racemates, Lux 2 could resolve the last racemic mixture. Finally, optimized conditions of separation are defined. Chirality, 2010. © 2009 Wiley‐Liss, Inc.     

桃蚜诱捕色板的青-洋红-黄-黑四色模式优化

采用计算机模拟混色技术,结合正交设计,定量测定了有翅桃蚜Myzus persicae(Sulzer)对青(C)、洋红(M)、黄(Y)和黑(K)4色成分模式混合色的选择性反应。第1组L25(56)试验结果表明,因子效应顺序为:Y﹥M﹥K﹥C。最佳理论混合色参数为C=25%、Y=25%、M=100%、K=0,模拟色板的叶色竞争系数(LCC)达77.78%。第2组L16(45)正交试验结果表明,当C、M、Y、K分别在10%～40%、10%～40%、85%～100%和0～15%区间变化时,对所有处理的叶色竞争系数均无显著影响。模拟色板叶色竞争系数与黄色成分和黑色成分的回归方程分别为LCC=0.0390Y2-0.1875Y+0.5591(R2=0.9913)和LCC=0.0163K2-0.1237K+0.6176(R2=0.7926)。     

Regulation of serotonin receptor function in the nervous system by lipid rafts and adaptor proteins

5-HT is a phylogenetically conserved monoaminergic neurotransmitter which is crucial for a number of physiological processes and is dysregulated in several disease states including depression, anxiety and schizophrenia. 5-HT neurons in the central nervous system are localized in the raphe nuclei and project to a wide range of target areas. 5-HT exerts its functions through 14 subtypes of 5-HT receptors. The tertiary structures of seven transmembrane 5-HT receptors contain several important features, including cholesterol consensus motifs, prominent intracellular loops and free C-termini. Alterations of cholesterol levels affect binding of ligands to 5-HT receptors and cholesterol-enriched microdomains in the cell membrane, termed lipid rafts, regulate 5-HT receptor internalization and signaling. The intracellular loops and the C-termini of 5-HT receptors provide binding sites for interacting adaptor proteins. Adaptor proteins affect internalization, desensitization as well as G-protein dependent and independent signaling via 5-HT receptors. We will here briefly review recent progress on the role of lipid rafts and adaptor proteins in the regulation of localization, trafficking, signaling and ligand bias of 5-HT receptors.     

Adventures in time and space: Nonlinearity and complexity of cytokine effects on stem cell fate decisions

Cytokines are central factors in the control of stem cell fate decisions and, as such, they are invaluable to those interested in the manipulation of stem and progenitor cells for clinical or research purposes. In their in vivo niches or in optimized cultures, stem cells are exposed to multiple cytokines, matrix proteins and other cell types that provide individual and combinatorial signals that influence their self‐renewal, proliferation and differentiation. Although the individual effects of cytokines are well‐characterized in terms of increases or decreases in stem cell expansion or in the production of specific cell lineages, their interactions are often overlooked. Factorial design experiments in association with multiple linear regression is a powerful multivariate approach to derive response‐surface models and to obtain a quantitative understanding of cytokine dose and interactions effects. On the other hand, cytokine interactions detected in stem cell processes can be difficult to interpret due to the fact that the cell populations examined are often heterogeneous, that cytokines can exhibit pleiotropy and redundancy and that they can also be endogenously produced. This perspective piece presents a list of possible biological mechanisms that can give rise to positive and negative two‐way factor interactions in the context of in vivo and in vitro stem cell‐based processes. These interpretations are based on insights provided by recent studies examining intra‐ and extra‐cellular signaling pathways in adult and embryonic stem cells. Cytokine interactions have been classified according to four main types of molecular and cellular mechanisms: (i) interactions due to co‐signaling; (ii) interactions due to sequential actions; (iii) interactions due to high‐dose saturation and inhibition; and (iv) interactions due to intercellular signaling networks. For each mechanism, possible patterns of regression coefficients corresponding to the cytokine main effects, quadratic effects and two‐way interactions effects are provided. Finally, directions for future mechanistic studies are presented. Biotechnol. Bioeng. 2010;106: 173–182. © 2010 Wiley Periodicals, Inc.