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961.
Quantitative real-time polymerase chain reaction for determination of plasmid copy number in bacteria 总被引:1,自引:0,他引:1
A method for determination of plasmid copy number (PCN) in bacteria by real-time quantitative polymerase chain reaction (QPCR) was developed as an alternative to current PCN assays. Conventional methods for PCN estimation are generally not of high throughput, laborious, have low reproducibility, require large amounts of biological samples and are applicable only for a narrow dynamic range. Real-time QPCR, using the ABI Prism 7000, was able to sensitively detect the quantity of the pUC ori based plasmid, NS3, transformed into Escherichia coli host, DH5alpha, to be 411+/-6.1. The PCN of pBR322 plasmid DNA in DH5alpha was estimated to be 40+/-0.6 which is within its previously reported PCN range of approximately 30 to 70. QPCR was found to show good reproducibility and high sensitivity in detecting a two fold difference in template concentration, and a wide linear dynamic range covering 0.5 pg to 50 ng of DNA. PCNs of DH5alpha bearing plasmids pBR322 and NS3 computed from real-time QPCR assay were validated by that of agarose gel assay, and a marginal difference of only 13.0% and 10.7% was found for the two plasmids respectively. The QPCR assay was able to detect changes in PCN of plasmid producing DH5alpha during the course of a 2 l batch fermentation. 相似文献
962.
粤东地区重要外来有害植物叶蛋白含量的研究 总被引:7,自引:0,他引:7
用凯氏定氮法测定了粤东地区17种重要的外来植物粗蛋白含量.其中空心莲子草含量高达32.38%,另外薇甘菊、马缨丹、水葫芦、飞机草、空心莲子草等在叶蛋白的提取及叶蛋白产品的开发利用方面具有良好的前景. 相似文献
963.
Emerging strategies of lignin engineering and degradation for cellulosic biofuel production 总被引:6,自引:2,他引:4
Ethanol and other biofuels produced from lignocellulosic biomass represent a renewable, more carbon-balanced alternative to both fossil fuels and corn-derived or sugarcane-derived ethanol. Unfortunately, the presence of lignin in plant cell walls impedes the breakdown of cell wall polysaccharides to simple sugars and the subsequent conversion of these sugars to usable fuel. Recent advances in the understanding of lignin composition, polymerization, and regulation have revealed new opportunities for the rational manipulation of lignin in future bioenergy crops, augmenting the previous successful approach of manipulating lignin monomer biosynthesis. Furthermore, recent studies on lignin degradation in nature may provide novel resources for the delignification of dedicated bioenergy crops and other sources of lignocellulosic biomass. 相似文献
964.
965.
Wan L Lin CW Lin YJ Sheu JJ Chen BH Liao CC Tsai Y Lin WY Lai CH Tsai FJ 《Journal of cellular and molecular medicine》2008,12(3):876-888
The biological activities of type I interferons (IFNs) are mediated by their binding to a heterodimer receptor complex (IFNAR1 and IFNAR2), resulting in the activation of the JAK (JAK1 and TYK2)-STAT (1, 2, 3, 5 isotypes) signalling pathway. Although several studies have indicated that IFN-alpha and IFN-beta can activate complexes containing STAT6, the biological role of this activation is still unknown. We found that exposure of hepatoma cells (HuH7 and Hep3B) to IFN-alpha or IFN-beta led to the activation of STAT6. Activated STAT6 in turn induced the formation of STAT2: STAT6 complexes, which led to the secretion of IL-1Ra. The activation of STAT6 by type I IFN in hepatocytes was mediated by JAK1 and Tyk2. In addition, IFN-alpha or IFN-beta significantly enhanced the stimulatory effect of IL-1beta on production of IL-1Ra. The present study suggests a novel function of IFN-alpha and IFN-beta signalling in human hepatocytes. Our results provide evidence for the mechanism how IFN-alpha and IFN-beta modulate inflammatory responses through activation of STAT6 and production of secreted IL-1Ra. 相似文献
966.
Xiao Li Qingan Ren Yang Weng Haoyang Cai Yunmin Zhu Yizheng Zhang 《基因组蛋白质组与生物信息学报(英文版)》2008,6(3):175-185
Predicting protein-coding genes still remains a significant challenge. Although a variety of computational programs that use commonly machine learning methods have emerged, the accuracy of predictions remains a low level when implementing in large genomic sequences. Moreover, computational gene finding in newly se- quenced genomes is especially a difficult task due to the absence of a training set of abundant validated genes. Here we present a new gene-finding program, SCGPred, to improve the accuracy of prediction by combining multiple sources of evidence. SCGPred can perform both supervised method in previously well-studied genomes and unsupervised one in novel genomes. By testing with datasets composed of large DNA sequences from human and a novel genome of Ustilago maydi, SCGPred gains a significant improvement in comparison to the popular ab initio gene predictors. We also demonstrate that SCGPred can significantly improve prediction in novel genomes by combining several foreign gene finders with similarity alignments, which is superior to other unsupervised methods. Therefore, SCGPred can serve as an alternative gene-finding tool for newly sequenced eukaryotic genomes. The program is freely available at http://bio.scu.edu.cn/SCGPred/. 相似文献
967.
Xing H Cao Y Weng D Tao W Song X Wang W Meng L Xu G Zhou J Wang S Ma D 《Apoptosis : an international journal on programmed cell death》2008,13(2):213-223
Although multiple mechanisms have been implicated in chemoresistance, recent evidence has suggested that the attachment of
cells to extracellular matrix proteins such as fibronectin (FN) may mediate the signals that participate in cell survival
and resistance to apoptosis. We established previously that human ovarian cancer cells and breast cancer cells adhering to
FN acquire a survival advantage through activation of the PI3-kinase/Akt2 pathway. However, the mechanism by which Akt2 regulates
chemoresistance in adherent cells is unknown. In the present study, we have investigated the role of the interaction between
the Akt2/survivin survivial pathway and the ASK1/p38 apoptotic pathway in the phenomenon of resistance to docetaxel. We show
here that the resistance of FN-adhered A2780 or MDA-MB-231 cells to docetaxel requires survivin, and we present evidence that
attenuation of the antiapoptotic activity of survivin is p38-dependent. The activation of p38 kinase in response to docetaxel,
on the other hand, is abolished by FN adhesion. We further demonstrate that FN adhesion-mediated inhibition of p38 activation
was governed by Akt2 via the promotion of direct protein association of ASK1 with p38. Our results indicate for the first
time that p38 plays a critical role in FN adhesion-mediated resistance to docetaxel. The present findings may help us to understand
the formation of FN adhesion-mediated chemoresistance and facilitate development of novel antineoplastic strategies.
Note: Hui Xing and yang Chao contributed equally to this work. 相似文献
968.
Weng J Aphasizheva I Etheridge RD Huang L Wang X Falick AM Aphasizhev R 《Molecular cell》2008,32(2):198-209
In the mitochondria of trypanosomatids, the majority of mRNAs undergo massive uracil-insertion/deletion editing. Throughout the processes of pre-mRNA polyadenylation, guide RNA (gRNA) uridylylation and annealing to mRNA, and editing reactions, several multiprotein complexes must engage in transient interactions to produce a template for protein synthesis. Here, we report the identification of a protein complex essential for gRNA stability. The gRNA-binding complex (GRBC) interacts with gRNA processing, editing, and polyadenylation machineries and with the mitochondrial edited mRNA stability (MERS1) factor. RNAi knockdown of the core subunits, GRBC1 and GRBC2, led to the elimination of gRNAs, thus inhibiting mRNA editing. Inhibition of MERS1 expression selectively abrogated edited mRNAs. Homologous proteins unique to the order of Kinetoplastida, GRBC1 and GRBC2, form a stable 200 kDa particle that directly binds gRNAs. Systematic analysis of RNA-mediated and RNA-independent interactions involving the GRBC and MERS1 suggests a unified model for RNA processing in the kinetoplast mitochondria. 相似文献
969.
Shan L He P Li J Heese A Peck SC Nürnberger T Martin GB Sheen J 《Cell host & microbe》2008,4(1):17-27
Successful pathogens have evolved strategies to interfere with host immune systems. For example, the ubiquitous plant pathogen Pseudomonas syringae injects two sequence-distinct effectors, AvrPto and AvrPtoB, to intercept convergent innate immune responses stimulated by multiple microbe-associated molecular patterns (MAMPs). However, the direct host targets and precise molecular mechanisms of bacterial effectors remain largely obscure. We show that AvrPto and AvrPtoB bind the Arabidopsis receptor-like kinase BAK1, a shared signaling partner of both the flagellin receptor FLS2 and the brassinosteroid receptor BRI1. This targeting interferes with ligand-dependent association of FLS2 with BAK1 during infection. It also impedes BAK1-dependent host immune responses to diverse other MAMPs and brassinosteroid signaling. Significantly, the structural basis of AvrPto-BAK1 interaction appears to be distinct from AvrPto-Pto association required for effector-triggered immunity. These findings uncover a unique strategy of bacterial pathogenesis where virulence effectors block signal transmission through a key common component of multiple MAMP-receptor complexes. 相似文献
970.
Landi MT Dracheva T Rotunno M Figueroa JD Liu H Dasgupta A Mann FE Fukuoka J Hames M Bergen AW Murphy SE Yang P Pesatori AC Consonni D Bertazzi PA Wacholder S Shih JH Caporaso NE Jen J 《PloS one》2008,3(2):e1651