bluuebunny/crossref_metadata_2025_split huggingface dataset:
Burkholderia
spp. Alter
Pseudomonas aeruginosa
Physiology through Iron Sequestration
Authors: Weaver Valerie B. , Kolter Roberto 
Published: April 2004

ABSTRACT

Pseudomonas aeruginosa
and members of the
Burkholderia cepacia
complex often coexist in both the soil and the lungs of cystic fibrosis patients. To gain an understanding of how these different species affect each other's physiology when coexisting, we performed a screen to identify
P. aeruginosa
genes that are induced in the presence of
Burkholderia
. A random gene fusion library was constructed in
P. aeruginosa
PA14 by using a transposon containing a promoterless
lacZ
gene. Fusion strains were screened for their ability to be induced in the presence of
Burkholderia
strains in a cross-streak assay. Three fusion strains were induced specifically by
Burkholderia
species; all three had transposon insertions in genes known to be iron regulated. One of these fusion strains, containing a transposon insertion in gene PA4467, was used to characterize the inducing activity from
Burkholderia
. Biochemical and genetic evidence demonstrate that ornibactin, a siderophore produced by nearly all
B. cepacia
strains, can induce
P. aeruginosa
PA4467. Significantly, PA4467 is induced early in coculture with an ornibactin-producing but not an ornibactin-deficient
B. cepacia
strain, indicating that ornibactin can be produced by
B. cepacia
and detected by
P. aeruginosa
when the two species coexist.
Identification of a Phosphotransferase System of
Escherichia coli
Required for Growth on
N
-Acetylmuramic Acid
Authors: Dahl Ulrike , Jaeger Tina , Nguyen Bao Trâm , Sattler Julia M. , Mayer Christoph 
Published: April 2004

ABSTRACT

We report here that wild-type
Escherichia coli
grows on
N
-acetylmuramic acid (MurNAc) as the sole source of carbon and energy. Analysis of mutants defective in
N
-acetylglucosamine (GlcNAc) catabolism revealed that the catabolic pathway for MurNAc merges into the GlcNAc pathway on the level of GlcNAc 6-phosphate. Furthermore, analysis of mutants defective in components of the phosphotransferase system (PTS) revealed that a PTS is essential for growth on MurNAc. However, neither the glucose-, mannose/glucosamine-, nor GlcNAc-specific PTS (PtsG, ManXYZ, and NagE, respectively) was found to be necessary. Instead, we identified a gene at 55 min on the
E. coli
chromosome that is responsible for MurNAc uptake and growth. It encodes a single polypeptide consisting of the EIIB and C domains of a so-far-uncharacterized PTS that was named
murP
. MurP lacks an EIIA domain and was found to require the activity of the
crr
-encoded enzyme IIA-glucose (EIIA
Glc
), a component of the major glucose transport system for growth on MurNAc.
murP
deletion mutants were unable to grow on MurNAc as the sole source of carbon; however, growth was rescued by providing
murP
in
trans
expressed from an isopropylthiogalactopyranoside-inducible plasmid. A functional His
6
fusion of MurP was constructed, isolated from membranes, and identified as a polypeptide with an apparent molecular mass of 37 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis. Close homologs of MurP were identified in the genome of several bacteria, and we believe that these organisms might also be able to utilize MurNAc.
Genetic Analysis of theSalmonella entericaType III Secretion-Associated ATPase InvC Defines Discrete Functional Domains
Authors: Akeda Yukihiro , Galán Jorge E. 
Published: April 2004

ABSTRACTAn essential component of all type III secretion systems is a highly conserved ATPase that shares significant amino acid sequence similarity to the β subunit of the F0F1ATPases and is thought to provide the energy for the secretion process. We have performed a genetic and functional analysis of InvC, the ATPase associated with theSalmonella entericatype III secretion system encoded within its pathogenicity island 1. Through a mutagenesis analysis, we have identified amino acid residues that are essential for specific activities of InvC, such as nucleotide hydrolysis and membrane binding. This has allowed us to define discrete domains of InvC that are specifically associated with different essential activities of this protein.
ZipA Is Required for Targeting ofDMinC/DicB, but NotDMinC/MinD, Complexes to Septal Ring Assemblies inEscherichia coli
Authors: Johnson Jay E. , Lackner Laura L. , Hale Cynthia A. , de Boer Piet A. J. 
Published: April 2004

ABSTRACTThe MinC division inhibitor is required for accurate placement of the septal ring at the middle of theEscherichia colicell. The N-terminal domain of MinC (ZMinC) interferes with FtsZ assembly, while the C-terminal domain (DMinC) mediates both dimerization and complex formation with either MinD or DicB. Binding to either of these activators greatly enhances the division-inhibitory activity of MinC in the cell. The MinD ATPase plays a crucial role in the rapid pole-to-pole oscillation of MinC that is proposed to force FtsZ ring formation to midcell. DicB is encoded by one of the cryptic prophages on theE. colichromosome (Qin) and is normally not synthesized. Binding of MinD or DicB toDMinC produces complexes that have high affinities for one or more septal ring-associated targets. Here we show that the FtsZ-binding protein ZipA is required for both recruitment of theDMinC/DicB complex to FtsZ rings and the DicB-inducible division block normally seen in MinC+cells. In contrast, none of the known FtsZ-associated factors, including ZipA, FtsA, and ZapA, appear to be specifically required for targeting of theDMinC/MinD complex to rings, implying that the two MinC/activator complexes must recognize distinct features of FtsZ assemblies. MinD-dependent targeting of MinC may occur in two steps of increasing topological specificity: (i) recruitment of MinC from the cytoplasm to the membrane, and (ii) specific targeting of the MinC/MinD complex to nascent septal ring assemblies on the membrane. Using membrane-tethered derivatives of MinC, we obtained evidence that both of these steps contribute to the efficiency of MinC/MinD-mediated division inhibition.
Expression Islands Clustered on the Symbiosis Island of the
Mesorhizobium loti
Genome
Authors: Uchiumi Toshiki , Ohwada Takuji , Itakura Manabu , Mitsui Hisayuki , Nukui Noriyuki , Dawadi Pramod , Kaneko Takakazu , Tabata Satoshi , Yokoyama Tadashi , Tejima Kouhei , Saeki Kazuhiko , Omori Hirofumi , Hayashi Makoto , Maekawa Takaki , Sriprang Rutchadaporn , Murooka Yoshikatsu , Tajima Shigeyuki , Simomura Kenshiro , Nomura Mika , Suzuki Akihiro , Shimoda Yoshikazu , Sioya Kouki , Abe Mikiko , Minamisawa Kiwamu 
Published: April 2004

ABSTRACT

Rhizobia are symbiotic nitrogen-fixing soil bacteria that are associated with host legumes. The establishment of rhizobial symbiosis requires signal exchanges between partners in microaerobic environments that result in mutualism for the two partners. We developed a macroarray for
Mesorhizobium loti
MAFF303099, a microsymbiont of the model legume
Lotus japonicus
, and monitored the transcriptional dynamics of the bacterium during symbiosis, microaerobiosis, and starvation. Global transcriptional profiling demonstrated that the clusters of genes within the symbiosis island (611 kb), a transmissible region distinct from other chromosomal regions, are collectively expressed during symbiosis, whereas genes outside the island are downregulated. This finding implies that the huge symbiosis island functions as clustered expression islands to support symbiotic nitrogen fixation. Interestingly, most transposase genes on the symbiosis island were highly upregulated in bacteroids, as were
nif
,
fix
,
fdx
, and
rpoN
. The genome region containing the
fixNOPQ
genes outside the symbiosis island was markedly upregulated as another expression island under both microaerobic and symbiotic conditions. The symbiosis profiling data suggested that there was activation of amino acid metabolism, as well as
nif-fix
gene expression. In contrast, genes for cell wall synthesis, cell division, DNA replication, and flagella were strongly repressed in differentiated bacteroids. A highly upregulated gene in bacteroids, mlr5932 (encoding 1-aminocyclopropane-1-carboxylate deaminase), was disrupted and was confirmed to be involved in nodulation enhancement, indicating that disruption of highly expressed genes is a useful strategy for exploring novel gene functions in symbiosis.
The Teicoplanin-Associated Locus Regulator (TcaR) and the Intercellular Adhesin Locus Regulator (IcaR) Are Transcriptional Inhibitors of the
ica
Locus in
Staphylococcus aureus
Authors: Jefferson Kimberly K. , Pier Danielle B. , Goldmann Donald A. , Pier Gerald B. 
Published: April 2004

ABSTRACT

Infections involving
Staphylococcus aureus
are often more severe and difficult to treat when the organism assumes a biofilm mode of growth. The polysaccharide poly-
N
-acetylglucosamine (PNAG), also known as polysaccharide intercellular adhesin, is synthesized by the products of the intercellular adhesin (
ica
) locus and plays a key role in biofilm formation. Numerous conditions and exogenous factors influence
ica
transcription and PNAG synthesis, but the regulatory factors and pathways through which these environmental stimuli act have been only partially characterized. We developed a DNA affinity chromatography system to purify potential regulatory proteins that bind to the
ica
promoter region. Using this technique, we isolated four proteins, including the staphylococcal gene regulator SarA, a MarR family transcriptional regulator of the teicoplanin-associated locus TcaR, DNA-binding protein II, and topoisomerase IV, that bound to the
ica
promoter. Site-directed deletion mutagenesis of
tcaR
indicated that TcaR was a negative regulator of
ica
transcription, but deletion of
tcaR
alone did not induce any changes in PNAG production or in adherence to polystyrene. We also investigated the role of IcaR, encoded within the
ica
locus but divergently transcribed from the biosynthetic genes. As has been shown previously in
Staphylococcus epidermidis
, we found that IcaR was also a negative regulator of
ica
transcription in
S. aureus
. We also demonstrate that mutation of
icaR
augmented PNAG production and adherence to polystyrene. Transcription of the
ica
locus, PNAG production, and adherence to polystyrene were further increased in a
tcaR icaR
double mutant. In summary, TcaR appeared to be a weak negative regulator of transcription of the
ica
locus, whereas IcaR was a strong negative regulator, and in their absence PNAG production and biofilm formation were enhanced.
The CoreEscherichia coliSignal Recognition Particle Receptor Contains Only the N and G Domains of FtsY
Authors: Eitan Asa , Bibi Eitan 
Published: April 2004

ABSTRACTPrevious studies have proposed that the N-terminal A domain (∼200 amino acid residues) of theEscherichia colisignal recognition particle (SRP) receptor, FtsY, is required for membrane targeting. In contrast to this suggestion, we show that A domain-truncated versions of FtsY, harboring only domains N and G, are functional. Therefore, we propose that N and G domains constitute the core SRP receptor.
Clostridium difficileIStron CdISt1: Discovery of a Variant Encoding Two Complete Transposase-Like Proteins
Authors: Hasselmayer Oliver , Braun Veit , Nitsche Claudia , Moos Michael , Rupnik Maja , von Eichel-Streiber Christoph 
Published: April 2004

ABSTRACTScreening aClostridium difficilestrain collection for the chimeric element CdISt1, we identified two additional variants, designated CdISt1-0 and CdISt1-III. In in vitro assays, we could prove the self-splicing ribozyme activity of these variants. Structural comparison of all known CdISt1variants led us to define four types of IStrons that we designated CdISt1-0 through CdISt1-III. Since CdISt1-0 encodes two complete transposase-like proteins (TlpA and TlpB), we suggest that it represents the original genetic element, hypothesized before to have originated by fusion of a group I intron and an insertion sequence element.
SIMULATION METHODS FOR LINEAR FRACTIONAL STABLE MOTION AND FARIMA USING THE FAST FOURIER TRANSFORM
Authors: STOEV STILIAN , TAQQU MURAD S. 
Published: March 2004

We present efficient methods for simulation, using the Fast Fourier Transform (FFT) algorithm, of two classes of processes with symmetric α-stable (SαS) distributions. Namely, (i) the linear fractional stable motion (LFSM) process and (ii) the fractional autoregressive moving average (FARIMA) time series with SαS innovations. These two types of heavy-tailed processes have infinite variances and long-range dependence and they can be used in modeling the traffic of modern computer telecommunication networks. We generate paths of the LFSM process by using Riemann-sum approximations of its SαS stochastic integral representation and paths of the FARIMA time series by truncating their moving average representation. In both the LFSM and FARIMA cases, we compute the involved sums efficiently by using the Fast Fourier Transform algorithm and provide bounds and/or estimates of the approximation error. We discuss different choices of the discretization and truncation parameters involved in our algorithms and illustrate our method. We include MATLAB implementations of these simulation algorithms and indicate how the practitioner can use them.
Second and Third Medical Termination of Pregnancy with Misoprostol without Mifepristone
Authors: Langer Bruno R. , Peter Christine , Firtion Céline , David Eric , Haberstich Renaud 
Published: April 2004

<i>Background:</i> Advances in prenatal diagnosis make it possible to detect many fetal pathologies for which a termination of pregnancy (TOP) is possible in France. In pregnancies which go beyond 3 months, the use of prostaglandins combined with mifepristone has simplified this procedure. Since mifepristone must be taken 48 h before using prostaglandins, we have used only misoprostol intravaginally. <i>Methods:</i> Our report deals with a continuous series of terminated pregnancies in the second and third trimesters. The time period in question is January 1, 1996 through July 31, 2001. When this treatment was used within the first 30 weeks of gestation, four tablets (800 µg) of misoprostol were administered intravaginally. When there were no contractions, two additional tablets (400 µg) of misoprostol were given orally every 3 h, not exceeding 3 times. Beyond 30 weeks of amenorrhoea, because of the risk of uterine rupture, the initial dose was lower: 1/4 tablet (50 µg) of misoprostol intravaginally was increased to 100 µg (1/2 tablet) every 3 h until expulsion. <i>Results:</i> In the second and third trimesters, 55 pregnancies were terminated medically; only 1 case was not successful. In the other 54 cases, the average time interval between administering misoprostol intravaginally and expulsion was 12.7 ± 8 h. Side effects included nausea or vomiting for 12 patients (22%) and hyperthermia for 11 patients (20%). Thirty-three patients (60%) had no side effects at all. In 10 cases (18%), the fetus and the placenta were removed in one movement. In 11 cases (20%), the placenta had to be removed by artificial means. In 7 cases (13%), a curettage with a curette foam was done. In the long run perspective, only 1 patient needed a curettage to remove placental residue. <i>Conclusion:</i> Treatment by misoprostol without mifepristone during the second and third trimesters makes it possible to terminate a pregnancy easily and quickly without significant complications.
The Closure of Iatrogenic Membrane Defects after Amniocentesis and Endoscopic Intrauterine Procedures
Authors: Young Bruce K. , Roman Ashley S. , MacKenzie Andrew P. , Stephenson Courtney D. , Minior Victoria , Rebarber Andrei , Timor-Tritsch Ilan 
Published: April 2004

<i>Objective:</i> To describe a new technique for wound closure after endoscopic intrauterine procedures which prevents amniotic fluid leakage after the procedure. <i>Study Design:</i> This is an observational study which reviews a new technique under an IRB-approved protocol. The rationale for this study was the increasing frequency of intrauterine endoscopic procedures. The most common complication of these procedures is persistent leakage of amniotic fluid from puncture sites, which can result in preterm labor and preterm delivery. Thus, these procedures carry a high morbidity rate that may overcome the benefit of the intervention. We have employed a new technique, which has successfully prevented amniotic fluid leakage following the procedure. The instruments used for the endoscopic procedures were no larger than 3.5 mm for all cases. A sealant of platelets was rapidly injected followed by injection of fibrin glue and powdered collagen slurry at each puncture site. Sonography for modified AFI, clinical examination for nitrazine and ferning, and pad count were performed after each procedure at three intervals: immediately after the procedure, 24 h and 48 h. <i>Results:</i> Eight patients undergoing an endoscopic intrauterine procedure (either cord ligation for twin-twin transfusion syndrome or sealing of ruptured membranes after amniocentesis) were included. All patients were treated between 18 and 24 weeks of gestation. Sonography, clinical examination and pad count revealed no evidence of amniotic fluid leakage either intra-abdominally or vaginally in any of the patients. There was 1 patient who ruptured membranes 12 h after the procedure due to severe vomiting. Another patient elected to terminate the pregnancy 48 h after the procedure without evidence of leakage. The remaining patients continued for 8 weeks or more without fluid leakage. <i>Conclusion:</i> The technique described, immediate sealing of puncture wounds following endoscopic intrauterine procedures, is effective in preventing amniotic fluid loss after the procedure.
Gene Regulation of Renal-Osmotic Stress-Induced Na-Cl Organic Solute Cotransporter
Authors: Baba Tomoko , Nonoguchi Hiroshi , Itoh Kazuko , Nakayama Yushi , Kohda Yukimasa , Inoue Takeaki , Tomita Kimio 
Published: April 2004

<i>Background: </i>Na- and Cl-dependent organic solute cotransporters participate in transporting neurotransmitters in the brain and organic osmolytes in the kidney. <i>Methods: </i>We examined the intranephron localization and regulation of the renal osmotic-stress-induced Na-Cl organic solute cotransporter (ROSIT) mRNA expression using microdissected nephron segments from control and dehydrated rats and RT-PCR. To further know the mechanisms of gene regulation of ROSIT, microdissected proximal straight tubules (PST) were incubated in isotonic (290 mosm/kg H<sub>2</sub>O) or hyperosmotic (490– 1,090 mosm/kg H<sub>2</sub>O) solution. <i>Results: </i>ROSIT mRNA was expressed predominantly in PST and to a lesser extent in cortical thick ascending limbs and cortical collecting ducts in control rats, and dehydration caused an increase in the expression in whole nephron segments. ROSIT mRNA in PST was decreased with time by incubation in isotonic solution. Incubation of PST in hypertonic solution by adding NaCl increased mRNA expression as early as 15 min (1.5- and 3-fold at 15 and 30 min, respectively). This stimulating effect of NaCl was largest at 890 mosm/kg H<sub>2</sub>O. Hypertonicity by mannitol or myoinositol also increased ROSIT mRNA expression. In contrast, hyperosmolality by urea reduced ROSIT mRNA expression. GAPDH mRNA expression, an internal standard, did not change by incubation in NaCl or mannitol solution. <i>Conclusion: </i>In summary, ROSIT mRNA expression was most abundant in PST in control and it was stimulated in whole nephron segments by dehydration. ROSIT mRNA expression in PST was stimulated by hypertonicity but not by urea. These data suggest that ROSIT may participate in the transport of amino acid under control conditions and organic osmolytes in dehydration.
Retinal Morphology and Electrophysiology of Two Caprimulgiformes Birds: The Cave-Living and Nocturnal Oilbird <i>(Steatornis caripensis)</i>, and the Crepuscularly and Nocturnally Foraging Common Pauraque <i>(Nyctidromus albicollis)</i>
Authors: Rojas L.M. , Ramírez Y. , McNeil R. , Mitchell M. , Marín G. 
Published: April 2004

Oilbirds <i>(Steatornis caripensis)</i> breed in the total darkness of caves and forage at night on fruits. Common pauraques <i>(Nyctidromus albicollis)</i> are crepuscular and nocturnal foragers on flying insects. We examined if their retinal structure and function can be correlated with their types and periods of activity. Electroretinograms (ERGs) were obtained from anesthetized birds in photopic and scotopic conditions to a wide range of light intensities, following which the retinas were processed for histological analysis. Retinal sensitivity is higher in oilbirds than in common pauraques. Under scotopic conditions with maximum flash luminance, the average (± 95% CI) b-wave amplitude of oilbirds is double that of common pauraques (500.4 ± 49.8 and 245.4 ± 40.9 µV, respectively) but, under photopic conditions, the results are the reverse (common pauraque: 69.4 ± 18.1; oilbird: 23.0 ± 4.4 µV). On the other hand, the retina of both species is highly rod-dominated, but rods are highly more numerous in oilbirds than in common pauraques (rods:cones ratio: 123:1 and 5:1, respectively). In oilbirds, rods are largely thinner and their outer segments are 1.0 µm in diameter and 18.6 µm in length. They are distributed over various levels in the photoreceptor layers, an arrangement known for deep-sea fishes, but so far unknown for birds. In common pauraques, rods are patchily distributed and their outer segments are 4.0 µm in diameter and 53 µm in length. The oilbirds rod thinness allows more rods per area unit, and thus to catch more photons per area unit under darkness, while the low cone number suggests that the species has poor daytime vision, which concurs with the species cavernicolous daytime habits. The lower rod number of common pauraques, compared to oilbirds, appears counterbalanced by their patchiness and longer and thicker outer segments to provide high retinal sensitivity. In addition, common pauraques also have a tapetum. These features, combined with a higher proportion of cones, show that common pauraques are well equipped for crepuscular and nocturnal foraging on flying insects in an open environment.
Population prevalence of psychiatric disorders in Chile: 6-month and 1-month rates
Authors: Vicente Benjamin , Kohn Robert , Rioseco Pedro , Saldivia Sandra , Baker Christine , Torres Silvero 
Published: March 2004

BackgroundFew South American studies have examined current prevalence rates of psychiatric disorders.AimsTo examine prevalence rates in a nationally representative adult population from Chile.MethodThe Composite International Diagnostic Interview was administered to a stratified random sample of 2978 individuals from four provinces representative of the country's population. Six-month and 1-month prevalence rates were estimated. Demographic correlates, comorbidity and service use were examined.ResultsNearly a fifth of the Chilean population had had a psychiatric disorder during the preceding 6 months. The 6-month and 1-month prevalence rates were 19.7% and 16.7% respectively. For the 6-month prevalence the five most common disorders were simple phobia, social phobia, agoraphobia, major depressive disorder and alcohol dependence. Less than 30% of those with any psychiatric diagnosis had a comorbid psychiatric disorder and the majority of them had sought treatment from mental health services.ConclusionsCurrent prevalence studies are useful indicators of service needs. People with comorbid psychiatric conditions have high rates of service use. The low rate of comorbidity in Chile merits further study.