Cyclooxygenase 2 (COX2)-prostanoid pathway and liver diseases

Cycloocygenases 2 (COX2)-prostanoid pathway plays important and complex roles in the pathogenesis of various liver diseases. Most studies indicated that COX2-prostanoid pathway might suppress hepatic fibrogenesis by decreasing proliferation, migration, and contractility of hepatic stellate cells (HSCs). In animal model, COX2-prostanoid pathway increases portal hypertension, which can be reduced by treatment with COX2 inhibitor. In cirrhosis, COX2-prostanoid pathway may reduce formation of ascites by enhancing free water excretion, and protect gastric mucosa from ulcerative insults. Aberrant expression of COX2 has been well associated with hepatocarcinogenesis. COX2 inhibitors can effectively suppress proliferation of hepatocellular carcinoma (HCC) cells. This provided rationale for further testing COX2 inhibitors as clinical agents for HCC chemoprovention. Further studies will be needed to examine how COX2 inhibitors affect pathogenesis of various liver diseases.     

A review of methods for interpretation of glycopeptide tandem mass spectral data

Despite the publication of several software tools for analysis of glycopeptide tandem mass spectra, there remains a lack of consensus regarding the most effective and appropriate methods. In part, this reflects problems with applying standard methods for proteomics database searching and false discovery rate calculation. While the analysis of small post-translational modifications (PTMs) may be regarded as an extension of proteomics database searching, glycosylation requires specialized approaches. This is because glycans are large and heterogeneous by nature, causing glycopeptides to exist as multiple glycosylated variants. Thus, the mass of the peptide cannot be calculated directly from that of the intact glycopeptide. In addition, the chemical nature of the glycan strongly influences product ion patterns observed for glycopeptides. As a result, glycopeptidomics requires specialized bioinformatics methods. We summarize the recent progress towards a consensus for effective glycopeptide tandem mass spectrometric analysis.     

人造生物皮肤

由活细胞和生物相容性材料制成的人造生物皮肤是第一种获得ＦＤＡ批准的组织工程产品,它们在治疗严重烧伤病人和顽固性溃疡病人具有很好的疗效。本综述了人造生物皮肤的特点、制备方法和作用机理,并介绍了一些组织工程皮肤产品。     

Morganella morganii urease: purification, characterization, and isolation of gene sequences

Morganella morganii, a very common cause of catheter-associated bacteriuria, was previously classified with the genus Proteus on the basis of urease production. M. morganii constitutively synthesizes a urease distinct from that of other uropathogens. The enzyme, purified 175-fold by passage through DEAE-Sepharose, phenyl-Sepharose, Mono-Q, and Superose 6 chromatography resins, was found to have a native molecular size of 590 kilodaltons and was composed of three distinct subunits with apparent molecular sizes of 63, 15, and 6 kilodaltons, respectively. Amino-terminal analysis of the subunit polypeptides revealed a high degree of conservation of amino acid sequence between jack bean and Proteus mirabilis ureases. Km for urea equalled 0.8 mM. Antiserum prepared against purified enzyme inhibited activity by 43% at a 1:2 dilution after 1 h of incubation. All urease activity was immunoprecipitated from cytosol by a 1:16 dilution. Antiserum did not precipitate ureases of other species except for one Providencia rettgeri strain but did recognize the large subunits of ureases of Providencia and Proteus species on Western blots (immunoblots). Thirteen urease-positive cosmid clones of Morganella chromosomal DNA shared a 3.5-kilobase (kb) BamHI fragment. Urease gene sequences were localized to a 7.1-kb EcoRI-SalI fragment. Tn5 mutagenesis revealed that between 3.3 and 6.6 kb of DNA were necessary for enzyme activity. A Morganella urease DNA probe did not hybridize with gene sequences of other species tested. Morganella urease antiserum recognized identical subunit polypeptides on Western blots of cytosol from the wild-type strain and Escherichia coli bearing the recombinant clone which corresponded to those seen in denatured urease. Although the wild-type strain and recombinant clone produced equal amounts of urease protein, the clone produced less than 1% of the enzyme activity of the wild-type strain.     

DL-蛋按酸及衍生物的合成与拆分研究进展

综述了蛋氨基酸及其衍生物的化学合成及化学拆分近年来的研究进展.第一部分讨论了DL-蛋氨酸及其衍生物的化学合成,包括丙烯醛法、丙二酸酯法,氨基内酯法等,并着重介绍了海因法.第二部分为 DL-蛋氨酸的手性拆分,主要包括膜分离,加合物、络合物形式分离,用苯丙氨酸拆分,衍生物分离等拆分方法,还介绍了生物酶拆分方法和其它有关拆分方法的进展.     

双效表达载体的构建及其U6启动子的功能效率鉴定

利用pBudcE4.1双表达载体构建shRNA与蛋白共表达载体,为双效疫苗的研制提供新的研究思路.以含U6启动子的载体为模板,PCR扩增得到U6启动子,用其置换载体pBudcE4.1内的CMV启动子的核心部分构建shRNA与蛋白共表达载体.用干扰绿色荧光蛋白表达的方法鉴定重组载体中的U6启动子能否启动shRNA的表达.经PCR扩增、双酶切鉴定及DNA测序证明成功构建了载体pBudcE4.1-U6.用干扰载体pBudcE4.1-U6-eGFPshRNA与含eGFP的载体共转染293T细胞后,荧光显微镜观察显示eGFP的表达量下降;流式细胞仪检测细胞的转染效率降低.研究结果证明U6启动子正常发挥作用. 成功构建RNAi与蛋白共表达载体,为利用该载体研制动物双效疫苗奠定了基础.     

STEME系统:一种助力体内定向进化的新工具

通过定向进化(directed evolution)可以快速进行蛋白工程改良及重要基因功能研究,以获得新型农艺性状突变体。近期,中国科学院遗传与发育生物学研究所高彩霞团队和李家洋团队合作构建了新型的饱和靶向内源诱变编辑器(saturated targeted endogenous mutagenesis editors, STEMEs),并在植物中实现了基因的定向进化和功能筛选。该系统融合了现有的2种单碱基编辑技术,成功实现在植物体内同时诱导C:G>T:A、A:T>G:C双碱基编辑,通过靶向OsACC羧基转移酶结构域编码序列定向进化出水稻除草剂抗性植株。这种在体内进行基因定向进化的新方法,对于今后农作物重要农艺性状的筛选和功能基因研究具有重要作用。本文对STEME系统的组成、编辑效率和应用原理进行介绍,并与已有的定向进化方法进行比较,为加速作物种质资源创新研究提供参考。