bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification and Characterization of an Extracellular Protease from
Xenorhabdus nematophila
Involved in Insect Immunosuppression
Authors: Caldas C. , Cherqui A. , Pereira A. , Simões N. 
Published: July 2002

ABSTRACT

Xenorhabdus nematophila
, a bacterium pathogenic for insects associated with the nematode
Steinernema carpocapsae
, releases high quantities of proteases, which may participate in the virulence against insects. Zymogram assays and cross-reactions of antibodies suggested that two distinct proteases were present. The major one, protease II, was purified and shown to have a molecular mass of 60 kDa and an estimated isoelectric point of 8.5. Protease II digested the chromogenic substrate
N
-tosyl-Gly-Pro-Arg-paranitroanilide (pNA) with
V
max
and

K
m

values of 0.0551 μM/min and 234 μM, respectively, and the substrate
dl
-Val-Leu-Arg-pNA with
V
max
and

K
m

values of 0.3830 μM/min and 429 μM, respectively. Protease II activity was inhibited 93% by Pefabloc SC and 45% by chymostatin. The optimum pH for protease II was 7, and the optimum temperature was 23°C. Proteolytic activity was reduced by 90% at 60°C for 10 min. Sequence analysis was performed on four internal peptides that resulted from the digestion of protease II. Fragments 29 and 45 are 75 and 68% identical to alkaline metalloproteinase produced by
Pseudomonas aeruginosa
. Fragment 29 is 79% identical to a metalloprotease of
Erwinia amylovora
and 75% identical to the protease C precursor of
Erwinia chrysanthemi
. Protease II showed no toxicity to hemocytes but destroyed antibacterial activity on the hemolymph of inoculated insects' larvae and reduced 97% of the cecropin A bacteriolytic activity.
Microbial Diversity of Hydrothermal Sediments in the Guaymas Basin: Evidence for Anaerobic Methanotrophic Communities
Authors: Teske Andreas , Hinrichs Kai-Uwe , Edgcomb Virginia , de Vera Gomez Alvin , Kysela David , Sylva Sean P. , Sogin Mitchell L. , Jannasch Holger W. 
Published: July 2002

ABSTRACT

Microbial communities in hydrothermally active sediments of the Guaymas Basin (Gulf of California, Mexico) were studied by using 16S rRNA sequencing and carbon isotopic analysis of archaeal and bacterial lipids. The Guaymas sediments harbored uncultured euryarchaeota of two distinct phylogenetic lineages within the anaerobic methane oxidation 1 (ANME-1) group, ANME-1a and ANME-1b, and of the ANME-2c lineage within the
Methanosarcinales
, both previously assigned to the methanotrophic archaea. The archaeal lipids in the Guaymas Basin sediments included archaeol, diagnostic for nonthermophilic euryarchaeota, and
sn
-2-hydroxyarchaeol, with the latter compound being particularly abundant in cultured members of the
Methanosarcinales
. The concentrations of these compounds were among the highest observed so far in studies of methane seep environments. The δ-
13
C values of these lipids (δ-
13
C = −89 to −58‰) indicate an origin from anaerobic methanotrophic archaea. This molecular-isotopic signature was found not only in samples that yielded predominantly ANME-2 clones but also in samples that yielded exclusively ANME-1 clones. ANME-1 archaea therefore remain strong candidates for mediation of the anaerobic oxidation of methane. Based on 16S rRNA data, the Guaymas sediments harbor phylogenetically diverse bacterial populations, which show considerable overlap with bacterial populations of geothermal habitats and natural or anthropogenic hydrocarbon-rich sites. Consistent with earlier observations, our combined evidence from bacterial phylogeny and molecular-isotopic data indicates an important role of some novel deeply branching bacteria in anaerobic methanotrophy. Anaerobic methane oxidation likely represents a significant and widely occurring process in the trophic ecology of methane-rich hydrothermal vents. This study stresses a high diversity among communities capable of anaerobic oxidation of methane.
Organophosphonate Utilization by the Thermophile
Geobacillus caldoxylosilyticus
T20
Authors: Obojska Agnieszka , Ternan Nigel G. , Lejczak Barbara , Kafarski Pawel , McMullan Geoff 
Published: July 2002

ABSTRACT

A strain of
Geobacillus caldoxylosilyticus
from central heating system water could utilize a number of organophosphonates as the sole phosphorus source for growth at 60°C. During growth on glyphosate, aminomethylphosphonate release to the medium was observed, and in cell extracts, a glyphosate oxidoreductase-type activity, producing stoichiometric amounts of aminomethylphosphonate and glyoxylate from glyphosate, was detectable.
Engineered Rhizosphere: the Trophic Bias Generated by Opine-Producing Plants Is Independent of the Opine Type, the Soil Origin, and the Plant Species
Authors: Mansouri Hounayda , Petit Annik , Oger Phil , Dessaux Yves 
Published: July 2002

ABSTRACT

In a previous study, we demonstrated that transgenic
Lotus
plants producing opines (which are small amino acid and sugar conjugates) specifically favor growth of opine-degrading rhizobacteria. The opine-induced bias was repeated and demonstrated with another soil type and another plant species (
Solanum nigrum
). This phenomenon is therefore independent of both soil type and plant species.
Construction and Application of Epitope- and Green Fluorescent Protein-Tagging Integration Vectors for
Bacillus subtilis
Authors: Kaltwasser Marcus , Wiegert Thomas , Schumann Wolfgang 
Published: July 2002

ABSTRACT

Here we describe the construction and application of six new tagging vectors allowing the fusion of two different types of tagging sequences, epitope and localization tags, to any
Bacillus subtilis
protein. These vectors are based on the backbone of pMUTIN2 and replace the
lacZ
gene with tagging sequences. Fusion of the tagging sequences occurs by PCR amplification of the 3′ terminal part of the gene of interest (about 300 bp), insertion into the tagging vector in such a way that a fusion protein will be synthesized upon integration of the whole vector via homologous recombination with the chromosomal gene. Three of these tagging sequences (FLAG, hemagglutinin, and c-Myc) allow the covalent addition of a short epitope tag and thereby detection of the fusion proteins in immunoblots, while three other tags (green fluorescent protein
+
, yellow fluorescent protein, and cyan fluorescent protein) are helpful in assigning proteins within one of the compartments of the cell. The versatility of these vectors was demonstrated by fusing these tags to the cytoplasmically located HtpG and the inner membrane protein FtsH.
Prevalence of Known P-Fimbrial G Alleles in
Escherichia coli
and Identification of a New Adhesin Class
Authors: Manning Shannon D. , Zhang Lixin , Foxman Betsy , Spindler Angela , Tallman Patricia , Marrs Carl F. 
Published: July 2002

ABSTRACT

Screening a large
Escherichia coli
collection for P-fimbrial adhesin classes identified 20 unclassifiable strains. Cloning and sequencing of
papG
from an unclassifiable strain identified another G allele. The novel adhesin gene has 65% identity to the class I adhesin gene, 44% identity to the class II adhesin gene, and 43% identity to the class III adhesin gene.
Role of Alveolar Macrophages in
Candida
-Induced Acute Lung Injury
Authors: Kubota Yutaka , Iwasaki Yoshinobu , Harada Hidehiko , Yokomura Ichiro , Ueda Mikio , Hashimoto Shinichi , Nakagawa Masao 
Published: July 2002

ABSTRACT

Recent studies have shown that alveolar macrophages (AMs) not only act as phagocytes but also play a central role as potent secretory cells in various lung diseases, including pneumonia and acute respiratory distress syndrome. The behavior of AMs during disseminated candidiasis, however, is insufficiently elucidated. This study is the first to report disseminated candidiasis in AM-depleted mice and to analyze the effect of AMs on
Candida
-induced acute lung injury. While all AM-sufficient mice died by day 2 after infection with
Candida albicans
, no mortality was observed among AM-depleted mice. Unexpectedly, the CFU numbers of
C. albicans
isolated from the lungs of AM-depleted mice were significantly higher than those for
C. albicans
isolated from AM-sufficient mice. The lung wet-to-dry weight ratio was lower for AM-depleted mice than for AM-sufficient mice, although this difference was not significant. We found that bronchoalveolar lavage fluid (BALF) from AM-depleted mice in candidemia contained fewer neutrophils than BALF from AM-sufficient mice. In addition, myeloperoxidase activities in lung homogenates of AM-depleted mice were significantly lower than those in homogenates of AM-sufficient mice. A significant decrease in levels of murine macrophage inflammatory protein 2 (MIP-2), a potent chemoattractant for neutrophils, was noted in lung homogenates from AM-depleted mice compared with levels in homogenates from AM-sufficient mice. Immunohistochemical studies using anti-MIP-2 antibodies revealed that AMs were the cellular source of MIP-2 within the lung during candidemia. We observed that AM depletion decreased levels of AM-derived neutrophil chemoattractant, alleviated acute lung injury during candidemia, and prolonged the survival of mice in candidemia, even though clearance of
C. albicans
from the lungs was reduced.
Bacterial Infection in Chronic Obstructive Pulmonary Disease in 2000: a State-of-the-Art Review
Authors: Sethi Sanjay , Murphy Timothy F. 
Published: July 2002

SUMMARYChronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States. The precise role of bacterial infection in the course and pathogenesis of COPD has been a source of controversy for decades. Chronic bacterial colonization of the lower airways contributes to airway inflammation; more research is needed to test the hypothesis that this bacterial colonization accelerates the progressive decline in lung function seen in COPD (the vicious circle hypothesis). The course of COPD is characterized by intermittent exacerbations of the disease. Studies of samples obtained by bronchoscopy with the protected specimen brush, analysis of the human immune response with appropriate immunoassays, and antibiotic trials reveal that approximately half of exacerbations are caused by bacteria. Nontypeable Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae are the most common causes of exacerbations, while Chlamydia pneumoniae causes a small proportion. The role of Haemophilus parainfluenzae and gram-negative bacilli remains to be established. Recent progress in studies of the molecular mechanisms of pathogenesis of infection in the human respiratory tract and in vaccine development guided by such studies promises to lead to novel ways to treat and prevent bacterial infections in COPD.
Genetic Control of Susceptibility toPorphyromonas gingivalis-Induced Alveolar Bone Loss in Mice
Authors: Baker Pamela J. , Dixon Mark , Roopenian Derry C. 
Published: July 2002

ABSTRACTPeriodontal disease affects a large percentage of the human population. Resorption of the alveolar bone of the jaw is a pivotal sequela of periodontal disease, because this bone is the attachment site for the periodontal ligaments that anchor the teeth. Using a murine model in which alveolar bone loss is induced by oral infection withPorphyromonas gingivalis, a gram-negative bacterium associated with human adult periodontal disease, we provide evidence suggesting that susceptibility to such bone loss is a genetically determined trait. AKR/J, DBA/2J, and BALB/cByJ or BALB/cJ mice were highly susceptible, while A/J, A/HeJ, 129/J, SJL/J, and C57BL/6J mice were much more resistant. When susceptible BALB/cJ and BALB/cByJ mice were crossed to resistant strains, two patterns were observed. (BALBc/ByJ × C57BL/6J)F1offspring were susceptible, suggesting C57BL/6J has recessive resistance alleles, while (BALB/cJ × A/J)F1mice were all resistant, suggesting that A/J mice have dominant resistance alleles. These results suggest a tractable genetic basis forP. gingivalis-induced alveolar bone loss and open the possibility of exploiting the mouse model to identify loci important for host susceptibility and resistance to periodontal disease.
Capsule Impedes Adhesion to and Invasion of Epithelial Cells by
Klebsiella pneumoniae
Authors: Sahly Hany , Podschun Rainer , Oelschlaeger Tobias A. , Greiwe Michael , Parolis Haralambos , Hasty David , Kekow Jörn , Ullmann Uwe , Ofek Itzhak , Sela Shlomo 
Published: July 2002

ABSTRACT

The adhesion of K21a, K26, K36, and K50 capsulated
Klebsiella
strains to ileocecal (HCT-8) and bladder (T24) epithelial cell lines was significantly lower than that of their corresponding spontaneous noncapsulated variants K21a/3, K26/1, K36/3, and K50/3, respectively. Internalization of the bacteria by both epithelial cell lines was also significantly reduced. Similarly, a capsule-switched derivative, K2(K36), that exhibited a morphologically larger K36 capsule and formed more capsular material invaded the ileocecal epithelial cell line poorly compared to the corresponding K2 parent strain. None of the capsulated strains exhibited significant mannose-sensitive type 1 fimbriae, whereas two of the noncapsulated variants K21a/3 and K50/3 exhibited potent mannose-sensitive hemagglutinating activity. Although hemagglutinating activity that could be attributed to mannose-resistant
Klebsiella
type 3 fimbriae was weak in all strains, in several cases the encapsulated parent strains exhibited lower titers than their corresponding noncapsulated variants. Although the level of adhesion to the ileocecal cells is not different from adhesion to bladder cells, bacterial internalization by bladder cells was significantly lower than internalization by ileocecal cells, suggesting that bladder cells lack components required for the internalization of
Klebsiella.
Interleukin-18 (IL-18) Enhances Innate IL-12-Mediated Resistance toToxoplasma gondii
Authors: Cai Guifang , Kastelein Robert , Hunter Christopher A. 
Published: July 2002

ABSTRACTInnate resistance toToxoplasma gondiiis dependent on the ability of interleukin-12 (IL-12) to stimulate natural killer (NK) cell production of gamma interferon (IFN-γ). Since IL-18 is a potent enhancer of IL-12-induced production of IFN-γ by NK cells, SCID mice (which lack an adaptive immune response) were used to assess the role of IL-18 in innate resistance toT. gondii. Administration of anti-IL-18 to SCID mice infected withT. gondiiresulted in an early reduction in serum levels of IFN-γ but did not significantly decrease resistance to this infection. In contrast, administration of exogenous IL-18 to infected SCID mice resulted in increased production of IFN-γ, reduced parasite burden, and a delay in time to death. The protective effects of IL-18 treatment correlated with increased NK cell numbers and cytotoxic activity at the local site of administration and with elevated levels of inducible nitrous oxide synthose in the spleens of treated mice. In addition, in vivo depletion studies demonstrated that the ability of exogenous IL-18 to enhance resistance toT. gondiiwas dependent on IL-12, IFN-γ, and NK cells. Together, these studies demonstrate that although endogenous IL-18 appears to have a limited role in innate resistance toT. gondii, treatment with IL-18 can augment NK cell-mediated immunity to this pathogen.
Role of Toxin Functional Domains in Anthrax Pathogenesis
Authors: Brossier Fabien , Weber-Levy Martine , Mock Michele , Sirard Jean-Claude 
Published: July 2002

ABSTRACT

We investigated the role of the functional domains of anthrax toxins during infection. Three proteins produced by
Bacillus anthracis
, the protective antigen (PA), the lethal factor (LF), and the edema factor (EF), combine in pairs to produce the lethal (PA+LF) and edema (PA+EF) toxins. A genetic strategy was developed to introduce by allelic exchange specific point mutations or in-frame deletions into
B. anthracis
toxin genes, thereby impairing either LF metalloprotease or EF adenylate cyclase activity or PA functional domains. In vivo effects of toxin mutations were analyzed in an experimental infection of mice. A tight correlation was observed between the properties of anthrax toxins delivered in vivo and their in vitro activities. The synergic effects of the lethal and edema toxins resulted purely from their enzymatic activities, suggesting that in vivo these toxins may act together. The PA-dependent antibody response to LF induced by immunization with live
B. anthracis
was used to follow the in vivo interaction of LF and PA. We found that the binding of LF to PA in vivo was necessary and sufficient for a strong antibody response against LF, whereas neither LF activity nor binding of lethal toxin complex to the cell surface was required. Mutant PA proteins were cleaved in mice sera. Thus, our data provide evidence that, during anthrax infection, PA may interact with LF before binding to the cell receptor. Immunoprotection studies indicated that the strain producing detoxified LF and EF, isogenic to the current live vaccine Sterne strain, is a safe candidate for use as a vaccine against anthrax.
Predictive Value of Nuclear Factor κB Activity and Plasma Cytokine Levels in Patients with Sepsis
Authors: Arnalich Francisco , Garcia-Palomero Esther , López Julia , Jiménez Manuel , Madero Rosario , Renart Jaime , Vázquez Juan José , Montiel Carmen 
Published: July 2002

ABSTRACT
The relationship between fluctuating cytokine concentrations in plasma and the outcome of sepsis is complex. We postulated that early measurement of the activation of nuclear factor κB (NF-κB), a transcriptional regulatory protein involved in proinflammatory cytokine expression, may help to predict the outcome of sepsis. We determined NF-κB activation in peripheral blood mononuclear cells of 34 patients with severe sepsis (23 survivors and 11 nonsurvivors) and serial concentrations of inflammatory cytokines (interleukin-6, interleukin-1, and tumor necrosis factor) and various endogenous antagonists in plasma. NF-κB activity was significantly higher in nonsurvivors and correlated strongly with the severity of illness (APACHE II score), although neither was related to the cytokine levels. Apart from NF-κB activity, the interleukin-1 receptor antagonist was the only cytokine tested whose level in plasma was of value in predicting mortality by logistic regression analysis. These results underscore the prognostic value of early measurement of NF-κB activity in patients with severe sepsis.
Lipopolysaccharide-Binding Protein and Phospholipid Transfer Protein Release Lipopolysaccharides from Gram-Negative Bacterial Membranes
Authors: Vesy C. J. , Kitchens R. L. , Wolfbauer G. , Albers J. J. , Munford R. S. 
Published: July 2002

ABSTRACTAlthough animals mobilize their innate defenses against gram-negative bacteria when they sense the lipid A moiety of bacterial lipopolysaccharide (LPS), excessive responses to this conserved bacterial molecule can be harmful. Of the known ways for decreasing the stimulatory potency of LPS in blood, the binding and neutralization of LPS by plasma lipoproteins is most prominent. The mechanisms by which host lipoproteins take up the native LPS that is found in bacterial membranes are poorly understood, however, since almost all studies of host-LPS interactions have used purified LPS aggregates. Using nativeSalmonella entericaserovar Typhimurium outer membrane fragments (blebs) that contained3H-labeled lipopolysaccharide (LPS) and35S-labeled protein, we found that two human plasma proteins, LPS-binding protein (LBP) and phospholipid transfer protein (PLTP), can extract [3H]LPS from bacterial membranes and transfer it to human high-density lipoproteins (HDL). Soluble CD14 (sCD14) did not release LPS from blebs yet could facilitate LBP-mediated LPS transfer to HDL. LBP, but not PLTP, also promoted the activation of human monocytes by bleb-derived LPS. Whereas depleting or neutralizing LBP significantly reduced LPS transfer from blebs to lipoproteins in normal human serum, neutralizing serum PLTP had no demonstrable effect. Of the known lipid transfer proteins, LBP is thus most able to transfer LPS from bacterial membranes to the lipoproteins in normal human serum.
TheshdAGene Is Restricted to Serotypes ofSalmonella entericaSubspecies I and Contributes to Efficient and Prolonged Fecal Shedding
Authors: Kingsley Robert A. , van Amsterdam Karin , Kramer Naomi , Bäumler Andreas J. 
Published: July 2002

ABSTRACTLittle is known about factors which enableSalmonellaserotypes to circulate within populations of livestock and domestic fowl. We have identified a DNA region which is present inSalmonellaserotypes commonly isolated from livestock and domestic fowl (S. entericasubspecies I) but absent from reptile-associatedSalmonellaserotypes (S. bongoriandS. entericasubspecies II to VII). This DNA region was cloned fromSalmonellaserotype Typhimurium and sequence analysis revealed the presence of a 6,105-bp open reading frame, designatedshdA, whose product's deduced amino acid sequence displayed homology to that of AIDA-I from diarrheagenicEscherichia coli, MisL of serotype Typhimurium, and IcsA ofShigella flexneri. TheshdAgene was located adjacent toxseAat 52 min, in a 30-kb DNA region which is not present inEscherichia coliK-12. A serotype TyphimuriumshdAmutant was shed with the feces in reduced numbers and for a shorter period of time compared to its isogenic parent. A possible role for theshdAgene during the expansion in host range ofS. entericasubspecies I to include warm-blooded vertebrates is discussed.
Curli Loci of
Shigella
spp
Authors: Sakellaris Harry , Hannink Nerissa K. , Rajakumar Kumar , Bulach Dieter , Hunt Meredith , Sasakawa Chihiro , Adler Ben 
Published: July 2002

ABSTRACT

An unstable chromosomal element encoding multiple antibiotic resistance in
Shigella flexneri
serotype 2a was found to include sequences homologous to the
csg
genes encoding curli in
Escherichia coli
and
Salmonella enterica
serovar Typhimurium. As curli have been implicated in the virulence of serovar Typhimurium, we investigated the
csg
loci in all four species of
Shigella
. DNA sequencing and PCR analysis showed that the
csg
loci of a wide range of
Shigella
strains, of diverse serotypes and different geographical distributions, were almost universally disrupted by deletions or insertions, indicating the existence of a strong selective pressure against the expression of curli. Strains of enteroinvasive
E. coli
(EIEC), which share virulence traits with
Shigella
spp. and cause similar diseases in humans, also possessed insertions or deletions in the
csg
locus or were otherwise unable to produce curli. Since the production of curli is a widespread trait in environmental isolates of
E. coli
, our results suggest that genetic lesions that abolish curli production in the closely related genus
Shigella
and in EIEC are pathoadaptive mutations.