云南红豆杉紫杉烷2α-O-苯甲酰转运酶基因的克隆及定性

通过RACE技术,克隆了云南红豆杉紫杉烷2α-O-苯甲酰转运酶基因(TyTBT),该酶催化2-去苯甲酰-7,13-二乙酰巴卡亭Ⅲ生成7,13-二乙酰巴卡亭Ⅲ,是紫杉醇合成途径中的关键酶之一.TyTBT基因cDNA全长1481 bp,含有1 320 bp的开放读码框,编码440个氨基酸的多肽,分子量为50 050 Da,等电点为6.17.氨基酸序列比对表明TyTBT同植物酰化酶家族的其它成员有较高的相似性,超过67%,同东北红豆杉和曼地亚红豆杉的紫杉烷2α-O-苯甲酰转运酶氨基酸序列的一致性和相似性达到最高,分别为95%和96%.广泛地比对分析证明这种较高的相似性在红豆杉属的其它酶家族中具有普遍性,进化树分析表明同东北红豆杉和曼地亚红豆杉的紫杉烷2α-O-苯甲酰转运酶(TBT)的相似性高于紫杉醇合成途径中的其它酰化酶.     

Gene expression profile in immunologically injured liver cell of mice

To study the gene expression profiles between immunologically injured liver cell and normal liver cell of mice and to screen on a large scale the differentially expressed genes associated with the formation of liver injury, the experimental mice were randomly divided into the normal group for controlling and the immunologically liver-injured group induced by BCG and LPS. The liver mRNA of the two groups were extracted respectively and reversely-transcribed to cDNA with the incorporation of different fluorescence (Cy3, Cy5) labeled dUTP as the hybridization probes. The mixed probes were hybridized to the cDNA microarray chips. The fluorescent signal results were acquired by scanner ScanArray 4000 and analyzed with software GenePix Pro 3.0. Among the 14112 target genes, 293 genes were found to be significantly differentially expressed, in which 188 genes were up-regulated and 105 genes were down-regulated. Based on the analysis of biological functions of those differentially expressed genes, it was indicated that the occurrence and development of mouse liver damage induced by BCG and LPS were highly correlated with the processes of immune reactions, cell synthesis, metabolism, apoptosis and transportation in liver cell, which might be quite important for elucidating the regulatory network of gene expression associated with the liver damage, also important for finally discovering the pathogenic mechanisms of immunological liver damage.     

Abnormal Pelage Color in an Isolated Population of <Emphasis Type="Italic">Alouatta guariba clamitans</Emphasis> Cabrera, 1940 in South Brazil

We located 4 brown howlers (1 adult male, 2 adult females, and 1 juvenile male) showing abnormally lighter pelage in 3 social groups comprising 5, 6, and 9 individuals in a 20 ha-forest fragment in the State of Rio Grande do Sul, Brazil. Two additional groups composed only of normally colored individuals also live in the fragment, which is isolated from nearby fragments by 267–1009 m. They were the only brown howlers with abnormal pelage color out of a total of 386 individuals belonging to 67 groups in 21 fragments in the 5876-ha study area. The isolation of the forest fragment, its high howler density (2.2 individuals⁄ha), and large group size (8.8 ± 2.4 individuals) may decrease the likelihood of successful immigration into the population, leading to an increased probability of inbreeding that may facilitate the expression of rare alleles.     

A gene trap approach to identify genes that control development

One methodology called gene trap represents a versatile strategy by which murine genes that control developmental events can be captured and identified with corresponding mutants produced at the same time. Gene trap methodology has been developed and several genes and their mutants have been analyzed, but almost all of the genes reported are those already known or murine homologs of other species. In this study, the efficiency of the gene trap methodology was improved and a novel mutant mouse strain named jumonji established which displayed an intriguing defect. Homozygous fetal mice died in utero and a significant proportion of the homozygotes showed abnormal groove formation on the neural plate and a defect in neural tube closure with a mixed genetic background of 129/Ola and BALB/c. The trapped gene believed to be responsible for these phenotypes encodes a novel nuclear protein. The results reveal that the gene trap approach can identify unknown interesting genes in murine development. The gene trap strategy, however, has several problems, the greatest of which is the difficulty in prescreening embryonic stem (ES) cells for interesting trapped genes. Recent studies are solving this problem and show that the prescreening of ES cells for genes with several characteristics is possible.     

Isolation and characterization of cDNA clones encoding a 18.8 kDa polypeptide,the product of the gene psaL,associated with photosystem I reaction center from spinach

Several cDNA clones encoding subunit XI of photosystem I reaction center (PSI-L) have been isolated from two gt11 expression libraries based on polyadenylated RNA of spinach seedlings illuminated for 4 and 16 h, respectively. The precursor polypeptide made from these recombinant DNAs in vitro can be efficiently imported into isolated spinach chloroplasts. It is correctly processed to the size of the authentic polypeptide and integrates into the photosystem I assembly. The 834 nucleotide sequence of the longest cDNA insert encodes a precursor polypeptide of 24 kDa (216 residues) and a mature protein of probably 18.8 kDa (169 residues). Hydropathy analysis suggests that the polypeptide contains two transmembrane segments. The protein appears to originate in a single-copy gene in spinach and to be decoded from RNA species of ca. 900 bases.     

Mitotracker Green Is a P-Glycoprotein Substrate

P-glycoprotein has a widespread expression on normal tissues. The protein has also been strongly associated with the multidrug resistance phenotype (MDR) on tumor cells. The employment of flow cytometry and confocal microscopy has contributed to the discovery and application of new particular fluorescent dyes. Nevertheless, several studies are being performed in different cellular types neglecting the expression/activity of MDR proteins. Because many fluorochromes have been reported as P-glycoprotein substrates, an especial attention must be given to the properties of new dyes in the presence of MDR proteins. Flow cytometric analyzes of Mitotracker Green (MTG) fluorescence profile were performed in a human erythroleukemic cell line and its resistant counterpart. In this report we demonstrated that MTG, a probe used to evaluate the mitochondrial mass, is a P-glycoprotein substrate and its staining profile is dependent on the activity of this protein. In vitro studies on a human erythroleukemic cell line and its resistant counterpart revealed that MDR modulators (Cyclosporin A, Verapamil, and Trifluoperazine) alter the MTG fluorescence pattern on a resistant cell line. The findings suggest that attention should be given to the expression of P-glycoprotein when performing an evaluation of mitochondria properties with MTG.     

渗透胁迫调节的转基因表达对植物抗旱耐盐性的影响

干旱和盐渍是影响植物生长和农作物产量的最重要的环境因子,本文综述了近年来通过超量表达低分子量化合物和渗透肋迫保护蛋白等获得抗旱耐盐转基因植物的报道,旨在系统阐述转基因表达对植物抗旱耐盐性的影响。     

Identification of salt-stress responsive genes in rice (Oryza sativa L.) by cDNA array

To identify salt stress-responsive genes, we constructed a cDNA library with the salttolerant rice cultivar, Lansheng. About 15000 plasmids were extracted and dotted on filters with Biomeck 2000 HDRT system or by hand. Thirty genes were identified to display altered expression levels responding to 150 mmol/L NaCl. Among them eighteen genes were up-regulated and the remainders downregulated. Twenty-seven genes have their homologous genes in GenBank Databases. The expression of twelve genes was studied by Northern analysis. Based on the functions, these genes can be classified into five categories, including photosynthesis-related gene, transportrelated gene, metabolismrelated gene, stress-or resistancerelated gene and the others with various functions. The results showed that salt stress influenced many aspects of rice growth. Some of these genes may play important roles in plant salt tolerance.     

Altered temperature induction sensitivity of the lambda pR/cI857 system for controlled gene E expression in Escherichia coli

Cell lysis of Gram-negative bacteria can be efficiently achieved by expression of the cloned lysis gene E of bacteriophage PhiX174. Gene E expression is tightly controlled by the rightward lambda pR promoter and the temperature-sensitive repressor cI857 on lysis plasmid pAW12. The resulting empty bacterial cell envelopes, called bacterial ghosts, are currently under investigation as candidate vaccines. Expression of gene E is stringently repressed at temperatures up to 30 degrees C, whereas gene E expression, and thus cell lysis, is induced at temperatures higher than 30 degrees C due to thermal inactivation of the cI857 repressor. As a consequence, the production of ghosts requires that bacteria have to be grown at 28 degrees C before the lysis process is induced. In order to reflect the growth temperature of pathogenic bacteria in vivo, it seemed favorable to extend the heat stability of the lambda pR promoter/cI857 repressor system, allowing pathogens to grow at 37 degrees C before induction of lysis. In this study we describe a mutation in the lambda pR promoter, which allows stringent repression of gene E expression at temperatures up to 36 degrees C, but still permits induction of cell lysis at 42 degrees C.