bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leucine-Responsive Regulatory Protein (Lrp) Acts as a Virulence Repressor inSalmonella entericaSerovar Typhimurium
Authors: Baek Chang-Ho , Wang Shifeng , Roland Kenneth L. , Curtiss Roy 
Published: December 2008

ABSTRACTLeucine-responsive regulatory protein (Lrp) is a global gene regulator that influences expression of a large number of genes including virulence-related genes inEscherichia coliandSalmonella. No systematic studies examining the regulation of virulence genes by Lrp have been reported inSalmonella. We report here that constitutive expression of Lrp [lrp(Con)] dramatically attenuatesSalmonellavirulence while anlrpdeletion (Δlrp) mutation enhances virulence. Thelrp(Con) mutant caused pleiotropic effects that include defects in invasion, cytotoxicity, and colonization, whereas the Δlrpmutant was more proficient at these activities than the wild-type strain. We present evidence that Lrp represses transcription of key virulence regulator genes—hilA,invF, andssrA—inSalmonellapathogenicity island 1 (SPI-1) and 2 (SPI-2), by binding directly to their promoter regions, PhilA, PinvF, and PssrA. In addition, Western blot analysis showed that the expression of the SPI-1 effector SipA was reduced in thelrp(Con) mutant and enhanced in the Δlrpmutant. Computational analysis revealed putative Lrp-binding consensus DNA motifs located in PhilA, PinvF, and PssrA. These results suggest that Lrp binds to the consensus motifs and modulates expression of the linked genes. The presence of leucine enhanced Lrp binding to PinvFin vitro and the addition of leucine to growth medium decreased the level ofinvFtranscription. However, leucine had no effect on expression ofhilAandssrAor on cellular levels of Lrp. In addition, Lrp appears to be an antivirulence gene, since the deletion mutant showed enhanced cell invasion, cytotoxicity, and hypervirulence in BALB/c mice.
Growth Deficiencies ofNeisseria meningitidis pfsandluxSMutants Are Not Due to Inactivation of Quorum Sensing
Authors: Heurlier Karin , Vendeville Agnès , Halliday Nigel , Green Andrew , Winzer Klaus , Tang Christoph M. , Hardie Kim R. 
Published: December 2008

ABSTRACTThe activated methyl cycle (AMC) is a central metabolic pathway used to generate (and recycle) several important metabolites and enable methylation. Pfs and LuxS are considered integral components of this pathway because they convertS-adenosylhomocysteine (SAH) toS-ribosylhomocysteine (SRH) andS-ribosylhomocysteine to homocysteine (HCY), respectively. The latter reaction has a second function since it also generates the precursor of the quorum-sensing molecule autoinducer 2 (AI-2). By demonstrating that there was a complete lack of AI-2 production inpfsmutants of the causative agent of meningitis and septicemia,Neisseria meningitidis, we showed that the Pfs reaction is the sole intracellular source of the AI-2 signal. Analysis oflacZreporters and real-time PCR experiments indicated thatpfsis expressed constitutively from a promoter immediately upstream, and careful study of thepfsmutants revealed a growth defect that could not be attributed to a lack of AI-2. Metabolite profiling of the wild type and of apfsmutant under various growth conditions revealed changes in the concentrations of several AMC metabolites, particularly SRH and SAH and under some conditions also HCY. Similar studies established that anN. meningitidis luxSmutant also has metabolite pool changes and growth defects in line with the function of LuxS downstream of Pfs in the AMC. Thus, the observed growth defect ofN. meningitidis pfsandluxSmutants is not due to quorum sensing but is probably due to metabolic imbalance and, in the case ofpfsinactivation, is most likely due to toxic accumulation of SAH.
The
Escherichia coli
K5 Capsule Is Not Synthesized in a Protected Compartment within the Cytoplasm
Authors: Hudson Thomas , Goldrick Marie , Roberts Ian S. 
Published: December 2008

ABSTRACT

The intracellular expression of the K5 lyase enzyme, which degrades the K5 polysaccharide, decreased cell surface expression of the
Escherichia coli
K5 capsule. This indicates that biosynthesis of K5 polysaccharide in the cytoplasm is accessible to the action of K5 lyase and is not synthesized within a protected cytoplasmic compartment.
The R1162 Mob Proteins Can Promote Conjugative Transfer from Cryptic Origins in the Bacterial Chromosome
Authors: Meyer Richard 
Published: December 2008

ABSTRACT

The mobilization proteins of the broad-host-range plasmid R1162 can initiate conjugative transfer of a plasmid from a 19-bp locus that is partially degenerate in sequence. Such loci are likely to appear by chance in the bacterial chromosome and could act as cryptic sites for transfer of chromosomal DNA when R1162 is present. The R1162-dependent transfer of chromosomal DNA, initiated from one such potential site in
Pectobacterium atrosepticum
, is shown here. A second active site was identified in
Escherichia coli
, where it is also shown that large amounts of DNA are transferred. This transfer probably reflects the combined activity of the multiple cryptic origins in the chromosome. Transfer of chromosomal DNA due to the presence of a plasmid in the cytoplasm describes a previously unrecognized potential for the exchange of bacterial DNA.
The
Lactobacillus plantarum ftsH
Gene Is a Novel Member of the CtsR Stress Response Regulon
Authors: Fiocco Daniela , Collins Michael , Muscariello Lidia , Hols Pascal , Kleerebezem Michiel , Msadek Tarek , Spano Giuseppe 
Published: December 2008

ABSTRACT

FtsH proteins have dual chaperone-protease activities and are involved in protein quality control under stress conditions. Although the functional role of FtsH proteins has been clearly established, the regulatory mechanisms controlling
ftsH
expression in gram-positive bacteria remain largely unknown. Here we show that
ftsH
of
Lactobacillus plantarum
WCFS1 is transiently induced at the transcriptional level upon a temperature upshift. In addition, disruption of
ftsH
negatively affected the growth of
L. plantarum
at high temperatures. Sequence analysis and mapping of the
ftsH
transcriptional start site revealed a potential operator sequence for the CtsR repressor, partially overlapping the −35 sequence of the
ftsH
promoter. In order to verify whether CtsR is able to recognize and bind the
ftsH
promoter, CtsR proteins of
Bacillus subtilis
and
L. plantarum
were overproduced, purified, and used in DNA binding assays. CtsR from both species bound specifically to the
ftsH
promoter, generating a single protein-DNA complex, suggesting that CtsR may control the expression of
L. plantarum ftsH
. In order to confirm this hypothesis, a Δ
ctsR
mutant strain of
L. plantarum
was generated. Expression of
ftsH
in the Δ
ctsR
mutant strain was strongly upregulated, indicating that
ftsH
of
L. plantarum
is negatively controlled by CtsR. This is the first example of an
ftsH
gene controlled by the CtsR repressor, and the first of the low-G+C gram-positive bacteria where the regulatory mechanism has been identified.
Functional Differences of Two Distinct Catalases in
Mesorhizobium loti
MAFF303099 under Free-Living and Symbiotic Conditions
Authors: Hanyu Masaki , Fujimoto Hanae , Tejima Kouhei , Saeki Kazuhiko 
Published: December 2008

ABSTRACT

Protection against reactive oxygen species (ROS) is important for legume-nodulating rhizobia during the establishment and maintenance of symbiosis, as well as under free-living conditions, because legume hosts might assail incoming microbes with ROS and because nitrogenase is extremely sensitive to ROS. We generated mutants of two potential catalase genes in
Mesorhizobium loti
MAFF303099 to investigate their physiological significance. Biochemical results indicated that genes with the locus tags mlr2101 and mlr6940 encoded a monofunctional catalase and a bifunctional catalase-peroxidase, respectively, that were named
katE
and
katG
. Under free-living conditions, the
katG
mutant demonstrated an extended generation time and elevated sensitivity to exogenous H
2
O
2
, whereas the
katE
mutant exhibited no generation time extension and only a slight increase in sensitivity to exogenous H
2
O
2
. However, the
katE
mutant showed a marked decrease in its survival rate during the stationary phase. With regard to symbiotic capacities with
Lotus japonicus
, the
katG
mutant was indistinguishable from the wild type; nevertheless, the mutants with disrupted
katE
formed nodules with decreased nitrogen fixation capacities (about 50 to 60%) compared to those formed by the wild type. These mutant phenotypes agreed with the expression profiles showing that transcription of
katG
, but not
katE
, was high during the exponential growth phase and that transcription levels of
katE
versus
sigA
were elevated during stationary phase and were approximately fourfold higher in bacteroids than mid-exponential-phase cells. Our results revealed functional separation of the two catalases, as well as the importance of KatE under conditions of strong growth limitation.
Essential Role for the BacA Protein in the Uptake of a Truncated Eukaryotic Peptide in
Sinorhizobium meliloti
Authors: Marlow Victoria L. , Haag Andreas F. , Kobayashi Hajime , Fletcher Vivien , Scocchi Marco , Walker Graham C. , Ferguson Gail P. 
Published: December 2008

ABSTRACT

The inner membrane BacA protein is essential for the establishment of chronic intracellular infections by
Sinorhizobium meliloti
and
Brucella abortus
within plant and mammalian hosts, respectively. In their free-living state,
S. meliloti
and
B. abortus
mutants lacking BacA have reductions in their outer membrane lipid A very-long-chain fatty acid (VLCFA) contents and exhibit low-level resistance to the glycopeptide bleomycin in comparison to their respective parent strains. In this paper we investigate the hypothesis that BacA is involved in peptide uptake in
S. meliloti
. We determined that an
S. meliloti
Δ
bacA
mutant is completely resistant to a truncated form of the eukaryotic peptide Bac7, Bac7(1-16), and this phenotype appears to be independent of its lipid A alteration. Subsequently, we discovered that BacA and/or
Escherichia coli
SbmA is essential for fluorescently labeled Bac7(1-16) uptake in
S. meliloti
. Given that there are hundreds of root nodule-specific peptides within the legume host, our data suggest that BacA-mediated peptide uptake could play a central role in the chronic infection process of
S. meliloti
. However, since we determined that two symbiotically defective
S. meliloti bacA
site-directed mutants (with the Q193G and R389G mutations, respectively) with known reductions in their lipid A VLCFA contents are still capable of peptide uptake, these findings suggest that BacA-dependent peptide uptake cannot fully account for the essential role of BacA in the legume symbiosis. Further, they provide evidence that the BacA function that leads to the
S. meliloti
lipid A VLCFA modification plays a key role in the chronic infection of legumes.
Acute lung inflammation and ventilator-induced lung injury caused by ATP via the P2Y receptors: an experimental study
Authors: Matsuyama Hiroki , Amaya Fumimasa , Hashimoto Soshi , Ueno Hiroshi , Beppu Satoru , Mizuta Mitsuhiko , Shime Nobuaki , Ishizaka Akitoshi , Hashimoto Satoru 
Published: December 2008

AbstractBackgroundExtracellular adenosine 5'-triphosphate (ATP) is an endogenous signaling molecule involved in multiple biological phenomena, including inflammation. The effects of extracellular ATP in the lung have not been fully clarified. This study examined 1) the biological roles of extracellular ATP in the pathogenesis of lung inflammation and 2) the possibility of involvement of extracellular ATP in mechanical ventilation-induced lung injury.MethodsThe effects of intratracheal ATP on lung permeability, edema or lung inflammation were assessed by measurements of the lung wet-to-dry weight ratio and lung permeability index, immunohistochemistry and expression of key cytokines by real-time polymerase chain reaction. The ATP concentration in broncho-alveolar lavage (BAL) fluid from mice mechanically ventilated was measured by luciferin-luciferase assay. The suppressive effects of a P2 receptor antagonist on ventilator-induced lung inflammation were also examined.ResultsATP induced inflammatory reactions in the lung mainly via the ATP-P2Y receptor system. These reactions were alleviated by the co-administration of a specific P2 receptor antagonist. Mechanical ventilation with a large tidal volume caused lung inflammation and increased the ATP concentration in BAL fluid. P2 receptor antagonism partially mitigated the inflammatory effects of large tidal volume ventilation.ConclusionOur observations suggest that the ATP-P2Y receptor system is partially involved in the pathogenesis of ventilator-induced lung injury.
Minireview: Liver X Receptor β: Emerging Roles in Physiology and Diseases
Authors: Gabbi Chiara , Warner Margaret , Gustafsson Jan-Åke 
Published: December 2008

AbstractLiver X receptors, LXRα and LXRβ, are nuclear receptors belonging to the large family of transcription factors. After activation by oxysterols, LXRs play a central role in the control of lipid and carbohydrate metabolism as well as inflammation. The role of LXRα has been extensively studied, particularly in the liver and macrophages. In the liver it prevents cholesterol accumulation by increasing bile acid synthesis and secretion into the bile through ATP-binding cassette G5/G8 transporters, whereas in macrophages it increases cholesterol reverse transport. The function of LXRβ is still under investigation with most of the current knowledge coming from the study of phenotypes of LXRβ−/− mice. With these mice new emerging roles for LXRβ have been demonstrated in the pathogenesis of diseases such as amyotrophic lateral sclerosis and chronic pancreatitis. The present review will focus on the abnormalities described so far in LXRβ−/− mice and the insight gained into the possible roles of LXRβ in human diseases.
Pharmacokinetic and pharmacodynamic profile of a new sustained-release GH formulation, LB03002, in children with GH deficiency
Authors: Peter Ferenc , Savoy Conrad , Ji Hyi-Jeong , Juhasz Mihaly , Bidlingmaier Martin , Saenger Paul 
Published: December 2008

ObjectiveLB03002 is a novel, sustained-release recombinant human GH, developed for once-a-week s.c. injection. To evaluate the suitability for long-term GH replacement therapy in children with GH deficiency (GHD), the present study assessed the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of LB03002 at three doses.Study design and patientsThe randomised, comparator-controlled, assessor-blinded, phase II study assessed 37 (24 boys, 13 girls) pre-pubertal, GH-naïve children with GHD, in 11 European centres, for PK and PD analyses. GH, IGF1 and IGFBP3 concentrations were measured following the last daily GH dose and the first and 13th once-a-week administration of LB03002 at doses of 0.2, 0.5 or 0.7 mg/kg.ResultsGH Cmax values after the three doses of LB03002 were increased up to fourfold, with a clear dose proportionality. For each LB03002 dose, GH area under the concentration versus time curve did not increase from the first to 13th (month 3) administration, indicating no accumulation of circulating GH. IGF1 Cmax showed a progressive increase during LB03002 administration. Conversely, IGFBP3 showed a rapid increase in Cmax. IGF1 SDS were fully normalised after 3 months of treatment, whereas IGFBP3 SDS were already in the normal range for all the three LB03002 dosages after 1 week.ConclusionsAt the doses used, LB03002 has a suitable profile for long-term treatment to promote growth in children with GHD. The quantitative changes in IGF1 and IGFBP3 indicate adequate stimulation of the IGF system by LB03002 and the pattern of increase is comparable with that seen in GHD children in a standard IGF1 generation test using daily GH.
Molecular Assemblies on Insulating Ultrathin Films Analyzed by NC‐AFM and KPFM
Authors: Glatzel Thilo , Zimmerli Lars , Meyer Ernst 
Published: December 2008

AbstractRecently porphyrin‐based molecules have proven to be promising candidates to form self‐assembled structures on insulating surfaces. Their close similarity to hemoglobin and chlorophyll‐based molecules makes them promising candidates for functional building parts in molecular electronics. To analyze their opto‐electronic activity, new measurement methods have to be applied. We investigated the formation of such molecular assemblies on ultrathin insulating films by means of a room temperature non‐contact atomic force microscope (NC‐AFM) in combination with a Kelvin probe force microscope (KPFM). As a substrate we used a Cu(111) surface, where either ultrathin KBr or NaCl films are deposited. On those surfaces the evaporated cyano‐porphyrins are forming one‐ and two‐dimensional structures that are comparable to the ones observed on bulk alkali halides. The simultaneously measured surface potential clearly shows a material contrast between the molecules and the insulating films. Finally, we succeeded in obtaining variations of the surface potential induced by the molecular assemblies at the molecular level.
Modeling of NC‐AFM Imaging of Alkanethiols on the Au (111) Surface
Authors: Sushko Maria L. , Kalampokidis Alexandros , Gal Andrei Y. , Shluger Alexander L. 
Published: December 2008

AbstractWe investigate the mechanisms of contrast formation in NC‐AFM imaging of self‐assembled monolayers of alkanethiols on the Au (111) surface. Comparing the potential models with implicit and explicit electrostatics, we demonstrate that, similar to the imaging of polar solid surfaces, the electrostatic interaction plays the central role in contrast formation. Careful comparison of several tip models showed that the model of a clean SiO2 tip gives the closest agreement with the experimental data.
The Adhesion Molecule Esam1 Is a Novel Hematopoietic Stem Cell Marker
Authors: Ooi A. G. Lisa , Karsunky Holger , Majeti Ravindra , Butz Stefan , Vestweber Dietmar , Ishida Tatsuro , Quertermous Thomas , Weissman Irving L. , Forsberg E. Camilla 
Published: December 2008

Abstract
Hematopoietic stem cells (HSCs) have been highly enriched using combinations of 12–14 surface markers. Genes specifically expressed by HSCs as compared with other multipotent progenitors may yield new stem cell enrichment markers, as well as elucidate self-renewal and differentiation mechanisms. We previously reported that multiple cell surface molecules are enriched on mouse HSCs compared with more differentiated progeny. Here, we present a definitive expression profile of the cell adhesion molecule endothelial cell-selective adhesion molecule (Esam1) in hematopoietic cells using reverse transcription-quantitative polymerase chain reaction and flow cytometry studies. We found Esam1 to be highly and selectively expressed by HSCs from mouse bone marrow (BM). Esam1 was also a viable positive HSC marker in fetal, young, and aged mice, as well as in mice of several different strains. In addition, we found robust levels of Esam1 transcripts in purified human HSCs. Esam1−/− mice do not exhibit severe hematopoietic defects; however, Esam1−/− BM has a greater frequency of HSCs and fewer T cells. HSCs from Esam1−/− mice give rise to more granulocyte/monocytes in culture and a higher T cell:B cell ratio upon transplantation into congenic mice. These studies identify Esam1 as a novel, widely applicable HSC-selective marker and suggest that Esam1 may play roles in both HSC proliferation and lineage decisions.
A new 122 mm electromechanical drill for deep ice-sheet coring (DISC): 5. Experience during Greenland field testing
Authors: Johnson Jay A. , Mason William P. , Shturmakov Alexander J. , Haman Scott T. , Sendelbach Paul J. , Mortensen Nicolai B. , Augustin Laurent J. , Dahnert Kristina R. 
Published: December 2008

AbstractThe Deep Ice Sheet Coring (DISC) drill developed by Ice Coring and Drilling Services under contract with the US National Science Foundation is an electromechanical ice-drill system designed to take 122mm ice cores to depths of 4000 m. The new drill system was field-tested near Summit camp in central Greenland during the spring/summer of 2006. Testing was conducted to verify the performance of the DISC drill system and its individual components and to determine the modifications required prior to the system’s planned deployment for coring at the WAIS Divide site in Antarctica in the following year. The experiments, results and the drill crew’s experiences with the DISC drill during testing are described and discussed.
EPICA Dome C 2 drilling operations: performances, difficulties, results
Authors: Augustin L. , Panichi S. , Frascati F. 
Published: December 2008

AbstractThe European Project for Ice Coring in Antarctica (EPICA) Dome C 2 (EDC2) drilling was concluded on 21 December 2005, a few metres above bedrock. The drilling was stopped both for environmental reasons and because of the drilling difficulties encountered in ‘warm ice’. This paper describes in detail the progress and the performance of the EPICA drill, including the procedures needed to penetrate into ‘warm ice’ and their effects on core quality. Some drill technical data are also presented.
Deep drilling at Vostok station, Antarctica: history and recent events
Authors: Vasiliev N.I. , Talalay P.G. , Bobin N.E. , Chistyakov V.K. , Zubkov V.M. , Krasilev A.V. , Dmitriev A.N. , Yankilevich S.V. , Lipenkov V.Ya. 
Published: December 2008

AbstractDeep drilling into the ice sheet at Vostok station, Antarctica, was started by specialists of the Leningrad Mining Institute (since 1991, St Petersburg State Mining Institute) in 1970. Five deep holes were cored: hole No. 1 to 952 m; hole No. 2 to 450.4 m; hole No. 3G (3G-1, 3G-2) to 2201.7 m; hole No. 4G (4G-1, 4G-2) to 2546.4 m; and hole No. 5G (5G-1) to 3650.2 m depth. Drilling of hole 5G-1 is not yet complete. The deep drilling at Vostok station has had successes and problems. All the deep holes at Vostok have undergone at least one offset drilling operation because of problems with lost drills. These deviations were made successfully using a thermal drilling technique. Several drilling records have been achieved at Vostok station. The deepest dry hole, No. 1 (952 m), was made during Soviet Antarctic Expedition (SAE) 17 in 1972. The deepest fluid-filled hole, No. 5G-1, made by a thermal drill (TBZS-132), reached 2755 m during SAE 38 in 1993. The deepest fluid-filled hole in ice, No. 5G-1, was drilled with a KEMS-132 electromechanical drill and was stopped above Vostok Subglacial Lake at 3650.2 m depth during Russian Antarctic Expedition (RAE) 51 in 2006.
Drilling comparison in ‘warm ice’ and drill design comparison
Authors: Augustin L. , Motoyama H. , Wilhelms F. , Johnsen S. , Hansen S.B. , Talalay P. , Vasiliev N. 
Published: December 2008

AbstractFor the deep ice-core drilling community, the 2005/06 Antarctic season was an exciting and fruitful one. In three different Antarctic locations, Dome Fuji, EPICA DML and Vostok, deep drillings approached bedrock (the ice–water interface in the case of Vostok), emulating what had previously been achieved at NorthGRIP, Greenland, (summer 2003 and 2004) and at EPICA Dome C2, Antarctica (season 2004/05). For the first time in ice-core drilling history, three different types of drill (KEMS, JARE and EPICA) simultaneously reached the depth of ‘warm ice’ under high pressure. After excellent progress at each site, the drilling rate dropped and the drilling teams had to deal with refrozen ice on cutters and drill heads. Drills have different limits and perform differently. In this comparative study, we examine depth, pressure, temperature, pump flow and cutting speed. Finally, we compare a few parameters of ten different deep drills.