Search results for "Escher"
showing 10 items of 728 documents
Cloning and characterization of the histidine biosynthetic gene cluster of Streptomyces coelicolor A3(2).
1990
Abstract Biochemical and genetic data indicate that in Streptomyces coelicolor A3(2) the majority of the genes involved in the biosynthesis of histidine are clustered in a small region of the chromosome [Carere et al., Mol. Gen. Genet. 123 (1973) 219–224; Russi et al., Mol. Gen. Genet. 123 (1973) 225–232]. To investigate the structural organization and the regulation of these genes, we have constructed genomic libraries from S. coelicolor A3(2) in pUC vectors. Recombinant clones were isolated by complementation of an Escherichia coli hisBd auxotroph. A recombinant plasmid containing a 3.4-kb fragment of genomic DNA was further characterized. When cloned in the plasmid vector, pIJ699, this f…
Restriction analysis of lambda EMBL3 background recombinants: occurrence of lambda phages carrying a head to tail oriented left arm DNA sequence.
1989
Eight representative recombinant background clones of lambda EMBL3 were analysed using KpnI, BamHI, SalI, EcoRI and HindIII digestion. We found that lambda EMBL3 carries its own left arm in the BamHI cloning site. In the way, recombinant molecules were found to be generated which can grow on Escherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a restored BamHI site at the cos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated, BamHI cloning produces a large palindromic sequence consisting of two polylinkers. This BamHI site was incompletely cleaved in all case…
Point Mutation Rate of Bacteriophage ΦX174
2009
Abstract The point mutation rate of phage ΦX174 was determined using the fluctuation test. After identifying the genetic changes associated with the selected phenotype, we obtained an estimate of 1.0 × 10−6 substitutions per base per round of copying, which is consistent with Drake's rule (0.003 mutations per genome per round of copying in DNA-based microorganisms).
Metabolic Networks of Sodalis glossinidius: A Systems Biology Approach to Reductive Evolution
2012
BackgroundGenome reduction is a common evolutionary process affecting bacterial lineages that establish symbiotic or pathogenic associations with eukaryotic hosts. Such associations yield highly reduced genomes with greatly streamlined metabolic abilities shaped by the type of ecological association with the host. Sodalis glossinidius, the secondary endosymbiont of tsetse flies, represents one of the few complete genomes available of a bacterium at the initial stages of this process. In the present study, genome reduction is studied from a systems biology perspective through the reconstruction and functional analysis of genome-scale metabolic networks of S. glossinidius.ResultsThe functiona…
Comparison of necrotoxigenic Escherichia coli isolates from farm animals and from humans.
1999
Abstract Necrotoxigenic Escherichia coli (NTEC) isolated from animals and humans can belong to the same serogroups/types and produce or carry the genes coding for fimbrial and afimbrial adhesins of the same family, P, S, F17, and/or AFA, raising the question of a potential zoonotic source of human infection. The main purpose of this study was to compare 239 NTEC1 strains (45 from cattle, 65 from humans and 129 from piglets) and 98 NTEC2 strains from cattle, using a uniform and standardized typing scheme. The O serogroups and the biotypes recognized amongst NTEC1 and NTEC2 strains were quite varied, although some were more frequently observed (serogroups O2, O4, O6, O8, O18, O78, and O83 and…
Effect of Pseudomonas sp. MT5 baths on Flavobacterium columnare infection of rainbow trout and on microbial diversity on fish skin and gills
2005
Use of Pseudomonas sp. strain MT5 to prevent and treat Flavobacterium columnare infection was studied in 2 experiments with fingerling rainbow trout Oncorhynchus mykiss. In the first experiment, length heterogeneity analysis of PCR-amplified DNA fragments (LH-PCR) was used to assess the effect of antagonistic baths on the microbial diversity of healthy and experimentally infected fish. In the 148 samples studied, no difference was found between bathed and unbathed fish, and 3 fragment lengths were detected most frequently: 500 (in 75.7% of the samples), 523 (62.2%) and 517 bp (40.5%). The species contributing to these fragment sizes were Pseudomonas sp., Rhodococcus sp. and F. columnare, re…
Globalization and Political Legitimacy in Western Europe
2018
Is there a legitimacy crisis in contemporary democracies? This question, asked since the beginning of the 1970s, has been currently undergoing a revival (Kriesi in Politische Vierteljahresschrift 54:609–638, 2013; Fuchs and Escher in The Legitimacy of Regional Integration in Europe and the Americas. Palgrave Macmillan: Houndsmill/Basingstoke, pp. 75–97, 2015; Merkel in Krise der Demokratie. Zum schwierigen Verhaltnis von Theorie und Empirie. Springer VS: Wiesbaden, 2015; Wessels in How Europeans View and Evaluate Democracy. Oxford University Press: Oxford, pp. 235–256, 2016; Van Ham et al. in Myth and Reality of the Legitimacy Crisis. Explaining Trends and Cross-National Differences in Esta…
The inhibition of glycerol permeation through aquaglyceroporin-3 induced by mercury(II)
2016
Mercurial compounds are known to inhibit water permeation through aquaporins (AQPs). Although in the last years some hypotheses were proposed, the exact mechanism of inhibition is still an open question and even less is known about the inhibition of the glycerol permeation through aquaglyceroporins. Molecular dynamics (MD) simulations of human aquaporin-3 (AQP3) have been performed up to 200 ns in the presence of Hg2+ ions. For the first time, we have observed the unbiased passage of a glycerol molecule from the extracellular to cytosolic side. Moreover, the presence of Hg2+ ions covalently bound to Cys40 leads to a collapse of the aromatic/arginine selectivity filter (ar/R SF), blocking th…
DcuA of aerobically grownEscherichia coliserves as a nitrogen shuttle (L‐aspartate/fumarate) for nitrogen uptake
2018
DcuA of Escherichia coli is known as an alternative C4 -dicarboxylate transporter for the main anaerobic C4 -dicarboxylate transporter DcuB. Since dcuA is expressed constitutively under aerobic and anaerobic conditions, DcuA was suggested to serve aerobically as a backup for the aerobic (DctA) transporter, or for the anabolic uptake of C4 -dicarboxylates. In this work, it is shown that DcuA is required for aerobic growth with L-aspartate as a nitrogen source, whereas for growth with L-aspartate as a carbon source, DctA was needed. Strains with DcuA catalyzed L-aspartate and C4 -dicarboxylate uptake (like DctA), or an L-aspartate/C4 -dicarboxylate antiport (unlike DctA). DcuA preferred L-asp…
Functional citric acid cycle in an arcA mutant of Escherichia coli during growth with nitrate under anoxic conditions
1998
The operation of the citric acid cycle of Escherichia coli during nitrate respiration (anoxic conditions) was studied by measuring end products and enzyme activities. Excretion of products other than CO2, such as acetate or ethanol, was taken as an indication for a non-functional cycle. From glycerol, approximately 0.3 mol acetate was produced; the residual portion was completely oxidized, indicating the presence of a partially active citric acid cycle. In an arcA mutant devoid of the transcriptional regulator ArcA, glycerol was completely oxidized with nitrate as an electron acceptor, demonstrating derepression and function of the complete pathway. Glucose, on the other hand, was excreted …