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71.
Elias DA Tollaksen SL Kennedy DW Mottaz HM Giometti CS McLean JS Hill EA Pinchuk GE Lipton MS Fredrickson JK Gorby YA 《Archives of microbiology》2008,189(4):313-324
High-throughput analyses that are central to microbial systems biology and ecophysiology research benefit from highly homogeneous
and physiologically well-defined cell cultures. While attention has focused on the technical variation associated with high-throughput
technologies, biological variation introduced as a function of cell cultivation methods has been largely overlooked. This
study evaluated the impact of cultivation methods, controlled batch or continuous culture in bioreactors versus shake flasks,
on the reproducibility of global proteome measurements in Shewanella
oneidensis MR-1. Variability in dissolved oxygen concentration and consumption rate, metabolite profiles, and proteome was greater in
shake flask than controlled batch or chemostat cultures. Proteins indicative of suboxic and anaerobic growth (e.g., fumarate
reductase and decaheme c-type cytochromes) were more abundant in cells from shake flasks compared to bioreactor cultures, a finding consistent with
data demonstrating that “aerobic” flask cultures were O2 deficient due to poor mass transfer kinetics. The work described herein establishes the necessity of controlled cultivation
for ensuring highly reproducible and homogenous microbial cultures. By decreasing cell to cell variability, higher quality
samples will allow for the interpretive accuracy necessary for drawing conclusions relevant to microbial systems biology research. 相似文献
72.
Heterocyclic ketones as inhibitors of histone deacetylase 总被引:1,自引:0,他引:1
Vasudevan A Ji Z Frey RR Wada CK Steinman D Heyman HR Guo Y Curtin ML Guo J Li J Pease L Glaser KB Marcotte PA Bouska JJ Davidsen SK Michaelides MR 《Bioorganic & medicinal chemistry letters》2003,13(22):3909-3913
Several heterocyclic ketones were investigated as potential inhibitors of histone deacetylase. Nanomolar inhibitors such as 22 and 25 were obtained, the anti-proliferative activity of which were shown to be mediated by HDAC inhibition. 相似文献
73.
Karen Stephens Vincent M. Riccardi Marcia Rising Siu Ng Philip Green Francis S. Collins Kenneth S. Rediker Jody A. Powers Carol Parker Helen Donis-Keller 《Genomics》1987,1(4):353-357
A locus for von Recklinghausen neurofibromatosis (NF1) has recently been mapped near the chromosome 17 centromere. We have extended these linkage studies by genotyping 45 NF1 families with three DNA probes known to be linked to the chromosome 17 centromeric region. Of 34 families informative for NF1 and at least one of the three probes, 28 families show no recombinants with the disease gene. These data provide additional support for genetic homogeneity of NF1 and for a primary NF1 locus linked to the chromosome 17 centromere. Among the informative families were 7 families with apparent new NF1 mutations. Our data suggest that these mutations are probably at the chromosome 17 NF1 locus. 相似文献
74.
Bono JL Keen JE Miller LC Fox JM Chitko-McKown CG Heaton MP Laegreid WW 《Applied and environmental microbiology》2004,70(3):1855-1857
A commercially available real-time, rapid PCR test was evaluated for its ability to detect Escherichia coli O157. Both the sensitivity and specificity of the assay were 99% for isolates in pure culture. The assay detected 1 CFU of E. coli O157:H7 g(-1) in artificially inoculated bovine feces following enrichment. 相似文献
75.
Intergenic Complementation of Glucoamylase and Citric Acid Production in Two Species of Aspergillus 下载免费PDF全文
All auxotrophs of Aspergillus foetidus and all but two auxotrophs of A. niger which we isolated yield glucoamylase and citric acid, respectively, at levels below that of the prototrophic strain from which they were derived. Results of representative heterokaryon tests suggest that the nucleus was principally responsible for the inheritance of citric acid or glucoamylase production. Most somatic diploid strains of A. foetidus gave rise to higher yields of glucoamylase when compared to their haploid component strains. Both heterokaryons and somatic diploid strains of A. niger synthesized between auxotrophs which were simultaneously reduced in citric acid yields also gave rise to enhanced yields when compared with their haploid components. The yields of a heterokaryon and somatic diploid synthesized between two high producers of citric acid were not higher than those of respective haploid components. We concluded from these results that gene dosage (or ploidy) does not increase the yield of citric acid. The apparent enhancement in yields observed in diploids or heterokaryons synthesized between auxotrophs with reduced yields in both species can be interpreted as resulting from intergenic complementation. 相似文献
76.
Shen J Pavone A Mikulec C Hensley SC Traner A Chang TK Person MD Fischer SM 《Journal of proteome research》2007,6(1):273-286
Exposure of murine skin to tumor-promoting agents such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA) causes up-regulation of cyclooxygenase-2 (COX-2) and increased prostaglandin (PG) synthesis. Pharmacological inhibition of COX-2 significantly reduces skin tumor development. However, we previously demonstrated that K14.COX-2 transgenic (TG) mice that overexpressed COX-2 in the epidermis were unexpectedly resistant to tumor development under the classical 7,12-dimethylbenz[a]anthracene-TPA protocol. In the present study, we employed a proteomic approach of 2-dimensional gel electrophoresis (2-DE) and mass spectrometry to profile differentially expressed proteins in the epidermis of K14.COX-2 TG and wild-type control mice. Various 2-DE approaches were used to identify the maximum number of differentially expressed proteins: 20 for untreated samples, 3 for acetone-treated samples, and 22 for TPA-treated samples. These proteins include 14-3-3 sigma, numerous actin fragments, actin filament related proteins cofilin-1 and destrin, galectin-3, galectin-7, prohibitin, S100A6, S100A9, and many others. The differential expression of galectin-3, galectin-7, S100A9 was validated by Western blot analysis and/or immunohistochemical analysis. The current data suggest that some of the differentially expressed proteins might increase apoptosis and cell cycle arrest, which, in turn, may provide insight into the role of COX-2 in skin tumorigenesis. 相似文献
77.
Bencharit S Edwards CC Morton CL Howard-Williams EL Kuhn P Potter PM Redinbo MR 《Journal of molecular biology》2006,363(1):201-214
Human carboxylesterase 1 (hCE1) is a drug and endobiotic-processing serine hydrolase that exhibits relatively broad substrate specificity. It has been implicated in a variety of endogenous cholesterol metabolism pathways including the following apparently disparate reactions: cholesterol ester hydrolysis (CEH), fatty acyl Coenzyme A hydrolysis (FACoAH), acyl-Coenzyme A:cholesterol acyltransfer (ACAT), and fatty acyl ethyl ester synthesis (FAEES). The structural basis for the ability of hCE1 to perform these catalytic actions involving large substrates and products has remained unclear. Here we present four crystal structures of the hCE1 glycoprotein in complexes with the following endogenous substrates or substrate analogues: Coenzyme A, the fatty acid palmitate, and the bile acids cholate and taurocholate. While the active site of hCE1 was known to be promiscuous and capable of interacting with a variety of chemically distinct ligands, these structures reveal that the enzyme contains two additional ligand-binding sites and that each site also exhibits relatively non-specific ligand-binding properties. Using this multisite promiscuity, hCE1 appears structurally capable of assembling several catalytic events depending, apparently, on the physiological state of the cellular environment. These results expand our understanding of enzyme promiscuity and indicate that, in the case of hCE1, multiple non-specific sites are employed to perform distinct catalytic actions. 相似文献
78.
Holleran JP Glover ML Peters KW Bertrand CA Watkins SC Jarvik JW Frizzell RA 《Molecular medicine (Cambridge, Mass.)》2012,18(1):685-696
Numerous human diseases arise because of defects in protein folding, leading to their degradation in the endoplasmic reticulum. Among them is cystic fibrosis (CF), caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR ), an epithelial anion channel. The most common mutation, F508del, disrupts CFTR folding, which blocks its trafficking to the plasma membrane. We developed a fluorescence detection platform using fluorogen-activating proteins (FAPs) to directly detect FAP-CFTR trafficking to the cell surface using a cell-impermeant probe. By using this approach, we determined the efficacy of new corrector compounds, both alone and in combination, to rescue F508del-CFTR to the plasma membrane. Combinations of correctors produced additive or synergistic effects, improving the density of mutant CFTR at the cell surface up to ninefold over a single-compound treatment. The results correlated closely with assays of stimulated anion transport performed in polarized human bronchial epithelia that endogenously express F508del-CFTR. These findings indicate that the FAP-tagged constructs faithfully report mutant CFTR correction activity and that this approach should be useful as a screening assay in diseases that impair protein trafficking to the cell surface. 相似文献
79.
80.
Genomic maps of chromatin modifications have provided evidence for the partitioning of genomes into domains of distinct chromatin states, which assist coordinated gene regulation. The maintenance of chromatin domain integrity can require the setting of boundaries. The HS4 insulator element marks the 3' boundary of a heterochromatin region located upstream of the chicken β-globin gene cluster. Here we show that HS4 recruits the E3 ligase RNF20/BRE1A to mediate H2B mono-ubiquitination (H2Bub1) at this insulator. Knockdown experiments show that RNF20 is required for H2Bub1 and processive H3K4 methylation. Depletion of RNF20 results in a collapse of the active histone modification signature at the HS4 chromatin boundary, where H2Bub1, H3K4 methylation, and hyperacetylation of H3, H4, and H2A.Z are rapidly lost. A remarkably similar set of events occurs at the HSA/HSB regulatory elements of the FOLR1 gene, which mark the 5' boundary of the same heterochromatin region. We find that persistent H2Bub1 at the HSA/HSB and HS4 elements is required for chromatin boundary integrity. The loss of boundary function leads to the sequential spreading of H3K9me2, H3K9me3, and H4K20me3 over the entire 50 kb FOLR1 and β-globin region and silencing of FOLR1 expression. These findings show that the HSA/HSB and HS4 boundary elements direct a cascade of active histone modifications that defend the FOLR1 and β-globin gene loci from the pervasive encroachment of an adjacent heterochromatin domain. We propose that many gene loci employ H2Bub1-dependent boundaries to prevent heterochromatin spreading. 相似文献