人睫状神经营养因子基因克隆、表达、纯化及其生物活性

［摘 要］目的 克隆人睫状神经营养因子（hCNTF）基因，在大肠杆菌宿主系统中高效表达并纯化，获得具有生物活性的hCNTF蛋白。方法 以人染色体DNA为模板，经PCR扩增到编码CNTF成熟蛋白的cDNA序列，并克隆进原核表达载体 pBV220，在大肠杆菌 BL21（Gold）中进行表达，产物经 CM-Sepharose FF柱纯化后，以体外培养的鸡胚背根神经节（DRG）测定生物活性。结果 重组表达质粒pBV22Z- CNTF在大肠杆菌BL21（Gold）中获得了非融合的稳定、高效表达，目的蛋白占细胞总蛋白的45％左右，以可溶性和包涵体两种形式存在，表达上清及包涵体复性后经CM柱一步纯化纯度达90％以上；表达的重组hCNTF能促进培养的鸡胚背根神经节神经突起的生长。结论 基因工程rhCNTF的获得为进一步研究其结构功能关系和临床应用奠定基础。     

Hydrogenases, accessory genes and the regulation of [NiFe] hydrogenase biosynthesis in Thiocapsa roseopersicina

The purple (Sulphur) phototrophic bacterium, Thiocapsa roseopersicina BBS contains several [NiFe] hydrogenases, of which two are membrane bound. Mutant T. roseopersicina cells, carrying deletions in both gene clusters showed hydrogenase activity. This activity was located in the cytoplasm. The structural gene cluster hoxEFUYH was identified and sequenced. In addition, genes homologous to hupUV/hoxBC, the hydrogen sensing hydrogenase have been identified and sequenced.Regulation of hydrogenase biosynthesis was studied in detail for HydSL (renamed HynSL). A random mutagenesis system was optimised for T. roseopersicina. One of the mutations was in a gene similar to that coding for the HypF proteins in other organisms. Inactivation of the hypF gene resulted in a 60-fold increase in hydrogen evolution under nitrogen fixing conditions. In addition to hypF, the following accessory genes were identified: hydD, hupK, hypC1, hypC2, hypDE. Characterisation of the corresponding gene products and search for additional accessory genes are in progress.     

Yeast mutants with increased bacterial transposon Tn5 excision

Five complementing recessive mutations that exhibit increased bacterial transposon Tn5 precise excision in yeast Saccharomyces cerevisiae were obtained by ethylmethanesulfonate treatment. One of these mutations (tex1) was submitted to extensive genetic analysis. tex1 is a recessive temperature-sensitive mutation resulting in a 20-100-fold increase in Tn5 excision. It also has increased frequencies of ochre mutation reversion, of forward mutation to canavanine resistance, and loss of chromosome III or its right arm. The possible mechanism of tex1 effects is discussed.     

One‐step production of 2,3‐butanediol from starch by secretory over‐expression of amylase in Klebsiella pneumoniae

BACKGROUND: 2,3‐Butanediol (2,3‐BD) is a valuable chemical that can be biosynthesized from many kinds of substrates. For commercial biological production of 2,3‐BD, it is desirable to use cheap substrate without pretreatment, such as starch. However, there have been few reports on the production of 2,3‐BD directly from starch. RESULTS: In this work, gene malS coding for α‐amylase (EC 3.2.1.1) precursor was inserted into plasmid pUC18K, and secretory over‐expression of α‐amylase was achieved by engineered Klebsiella pneumoniae. The extracellular recombinant amylase accelerated the hydrolyzation of starch, and one‐step production of 2,3‐BD from starch was carried out by engineered K. pneumoniae. A 2,3‐BD concentration of 3.8 g L^?1 and yield of 0.19 g 2,3‐BD g^?1 starch were obtained after 24 h fermentation. CONCLUSION: The one‐step production of 2,3‐BD from starch was achieved by secretory over‐expression of amylase in K. pneumoniae. This would simplify the process and reduce the production cost considerably by enabling use of starch with minimal pretreatment. Copyright © 2008 Society of Chemical Industry     

Garner interference reveals dependencies between emotional expression and gaze in face perception.

The relationship between facial expression and gaze processing was investigated with the Garner selective attention paradigm. In Experiment 1, participants performed expression judgments without interference from gaze, but expression interfered with gaze judgments. Experiment 2 replicated these results across different emotions. In both experiments, expression judgments occurred faster than gaze judgments, suggesting that expression was processed before gaze could interfere. In Experiments 3 and 4, the difficulty of the emotion discrimination was increased in two different ways. In both cases, gaze interfered with emotion judgments and vice versa. Furthermore, increasing the difficulty of the emotion discrimination resulted in gaze and expression interactions. Results indicate that expression and gaze interactions are modulated by discriminability. Whereas expression generally interferes with gaze judgments, gaze direction modulates expression processing only when facial emotion is difficult to discriminate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oil yield and compressibility modeling during microscale expression: Criteria for linseed breeding

Seven linseed varieties were harvested at seven times before complete maturity. Microscale oilseed expressions were subsequently carried out on it. A pressure of 10 MPa was applied for 1 h under uniaxial stress. The results were characterized in terms of oil, water and mucilage content, harvest date and oil yield. The piston displacement versus time (creep curves) was described by a four‐Kelvin‐Voigt elements viscoelastic model. Parameters were derived from the model, such as the mechanical properties of seeds (compressibility moduli), showing that the viscoelastic model fits well the experimental data (R² ≈ 0.999). The modeling parameters were combined with some biochemical data in order to predict the kinetics of oil extraction.     

媒体同步关系的描述

由于多媒体信息系统中，需要集成各种数据类型，而这些数据类型又有着密切的时间关系，所以对于多媒体来说，同步问题是很重要的，而同步的基础是为同步关系建立一个独立于实现环境的抽象的表示模型，本文着重讨论几种描述媒体同步关系的模型。     

强激光大气传输热晕方程的积分表示

基于菲涅耳 基尔霍夫近似，运用格林函数方法导出了热晕方程的积分表达式，并以连续波(CW)稳态热晕为例进行了数值计算和讨论，结果表明我们所采用的方法是可行的。众所周知的菲涅耳 基尔霍夫衍射积分则是我们所得积分表达的一个特例。     

筛查基因突变的新技术——循环双脱氧指纹图谱法及其应用

建立了适用于大批量标本基因突变筛查的双脱氧指纹图谱法即ｄｄＦ。该技术民测定ＤＮＡ序列的双脱氧末端终止法及ＳＳＣＰ二者长处于一身，即只作一个双脱氧末端终止反应，然后将反应产物在与ＳＳＣＰ相同的电泳条件下进行聚丙烯酰胺凝胶电泳，这样有突变的样品不会漏检，阳性检出率高达１００％。     

CIMS软件开发工具：Petri网编辑器的语法分析及其实现

本文给出并发表达式语言的文法，并描述了Petri网编辑器的语法分析过程和中间代码的产生过程。解决了Petri网在计算机中的存贮结构问题，处理了可能会出现的重名变量，实现了从井发表达式语言到安全标号的Petri网的转换工作。