bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence of Multiple Regulatory Functions for the PtsN (IIA
Ntr
) Protein of
Pseudomonas putida
Authors: Cases Ildefonso , Lopez Juan-Antonio , Albar Juan-Pablo , De Lorenzo Vı́ctor 
Published: July 2002

ABSTRACT

The
ptsN
gene of
Pseudomonas putida
encodes IIA
Ntr
, a protein of the phosphoenol pyruvate:sugar phosphotransferase (PTS) system which is required for the C source inhibition of the ς
54
-dependent promoter
Pu
of the TOL (toluate degradation) plasmid pWW0. Using two-dimensional gel electrophoresis, we have examined the effect of
ptsN
disruption on the general expression pattern of
P. putida
. To this end, cells were grown in the presence or absence of glucose, and a 1,117-spot subset of the
P. putida
proteome was used as a reference for comparisons. Among all gene products whose expression was lowered by this carbon source (247 spots [about 22%]), only 6 behaved as
Pu
(i.e., were depressed in the
ptsN
background). This evidenced only a minor role for IIA
Ntr
in the extensive inhibition of gene expression in
P. putida
caused by glucose. However, the same experiments revealed a large incidence of glucose-independent effects brought about by the
ptsN
mutation. As many as 108 spots (ca. 9% of the cell products analyzed) were influenced, positively or negatively, by the loss of IIA
Ntr
. By matching this pattern with that of an
rpoN
::ΩKm strain of
P. putida
, which lacks the ς
54
protein, we judge that most proteins whose expression was affected by
ptsN
were unrelated to the alternative sigma factor. These data suggest a role of IIA
Ntr
as a general regulator, independent of the presence of repressive carbon sources and not limited to ς
54
-dependent genes.
Suppression of Hypersensitivity of
Escherichia coli acrB
Mutant to Organic Solvents by Integrational Activation of the
acrEF
Operon with the IS
1
or IS
2
Element
Authors: Kobayashi Kei , Tsukagoshi Norihiko , Aono Rikizo 
Published: July 2002

ABSTRACT

The AcrAB-TolC efflux pump plays an intrinsic role in resistance to hydrophobic solvents in
Escherichia coli. E. coli
OST5500 is hypersensitive to solvents due to inactivation of the
acrB
gene by insertion of IS
30
. Suppressor mutants showing high solvent resistance were isolated from OST5500. These mutants produced high levels of AcrE and AcrF proteins, which were not produced in OST5500, and in each mutant an insertion sequence (IS
1
or IS
2
) was found integrated upstream of the
acrEF
operon, coding for the two proteins. The suppressor mutants lost solvent resistance on inactivation of the
acrEF
operon. The solvent hypersensitivity of OST5500 was suppressed by introduction of the
acrEF
operon with IS
1
or IS
2
integrated upstream but not by introduction of the operon lacking the integrated IS. It was concluded that IS integration activated
acrEF
, resulting in functional complementation of the
acrB
mutation. The
acrB
mutation was also complemented by a plasmid containing
acrF
or
acrEF
under the control of P
lac
. The wild-type
tolC
gene was found to be essential for complementation of the
acrB
mutation by
acrEF
. Thus, it is concluded that in these cells a combination of the proteins AcrA, AcrF, and TolC or the proteins AcrE, AcrF, and TolC is functional in solvent efflux instead of the AcrAB-TolC efflux pump.
Bacteriophage SP6 Is Closely Related to Phages K1-5, K5, and K1E but Encodes a Tail Protein Very Similar to That of the Distantly Related P22
Authors: Scholl Dean , Adhya Sankar , Merril Carl R. 
Published: July 2002

ABSTRACT
The lytic salmonella phage SP6 encodes a tail protein with a high degree of sequence similarity to the tail protein of the biologically unrelated lysogenic salmonella phage P22. The SP6 tail gene is flanked by an upstream region that contains a promoter and a downstream region that contains a putative Rho-independent transcription terminator, giving it a cassette or modular structure almost identical to the structure of the tail genes of coliphages K1E, K5, and K1-5. It now appears that SP6, K1-5, K5, and K1E are very closely related but have different tail fiber proteins, giving them different host specificities.
Identification by Flagellum Display of an Epithelial Cell- and Fibronectin-Binding Function in the SlpA Surface Protein of
Lactobacillus brevis
Authors: Hynönen Ulla , Westerlund-Wikström Benita , Palva Airi , Korhonen Timo K. 
Published: July 2002

ABSTRACT

Depletion of the SlpA protein from the bacterial surface greatly reduced the adhesion of
Lactobacillus brevis
ATCC 8287 to the human intestinal cell lines Caco-2 and Intestine 407, the endothelial cell line EA-hy926, and the urinary bladder cell line T24, as well as immobilized fibronectin. For functional analysis of the SlpA surface protein, different regions of the
slpA
gene were expressed as internal in-frame fusions in the variable region of the
fliC
H7
gene of
Escherichia coli
. The resulting chimeric flagella carried inserts up to 275 amino acids long from the mature S-layer protein, which is 435 amino acids in size. The expression of the SlpA fragments on the chimeric flagella was assessed by immunoelectron microscopy and Western blotting using anti-SlpA antibodies, and their binding to human cells was assessed by indirect immunofluorescence. Chimeric flagella harboring inserts that represented the N-terminal part of the S-layer protein bound to the epithelial cell lines, whereas the C-terminal part of the S-layer protein did not confer binding on the flagella. The shortest S-layer peptide capable of detectable binding was 81 amino acid residues in size and represented residues 96 through 176 in the unprocessed S-layer protein. The bacteria and the chimeric flagella did not show detectable binding to erythrocytes, whereas the SlpA-expressing ATCC 8287 cells as well as the chimeric SlpA 96-245/FliC flagella bound to immobilized fibronectin. The N-terminal SlpA peptide 96-176 or 96-200 fused to FliC was not recognized in Western blotting or immunoelectron microscopy by a polyclonal serum raised against the S-layer protein; the antiserum, however, reacted in immunofluorescence with the ATCC 8287 cells. In contrast, an antiserum raised against the His-tagged peptide 96-245 of SlpA bound to the hybrid flagella with the N-terminal SlpA inserts but did not react with ATCC 8287 cells. The results identify the S-layer of
L. brevis
ATCC 8287 as an adhesin with affinity for human epithelial cells and fibronectin and locate the receptor-binding region within a fragment of 81 amino acids in the N-terminal part of the molecule, which in native S-layer seems inaccessible to antibodies.
Osmoregulation of Dimer Resolution at the Plasmid pJHCMW1
mwr
Locus by
Escherichia coli
XerCD Recombination
Authors: Pham Huong , Dery Ken J. , Sherratt David J. , Tolmasky Marcelo E. 
Published: July 2002

ABSTRACT

Xer-mediated dimer resolution at the
mwr
site of plasmid pJHCMW1 is osmoregulated in
Escherichia coli
. Whereas under low-salt conditions, the site-specific recombination reaction is efficient, under high-salt conditions, it proceeds inefficiently. Regulation of dimer resolution is independent of H-NS and is mediated by changes in osmolarity rather than ionic effects. The low level of recombination at high salt concentrations can be overcome by high levels of PepA or by mutating the ARG box to a sequence closer to the
E. coli
ARG box consensus. The central region of the
mwr
core recombination site plays a role in regulation of site-specific recombination by the osmotic pressure of the medium.
Bursitis Due to
Mycobacterium goodii
, a Recently Described, Rapidly Growing Mycobacterium
Authors: Friedman N. Deborah , Sexton Daniel J. 
Published: July 2002

ABSTRACT

We report a case of olecranon bursitis due to
Mycobacterium goodii
in a 60-year-old man. Prior to recognition of his infection, he received intrabursal steroids and underwent olecranon bursectomy. His infection was cured with antimicrobial therapy consisting of doxycycline and ciprofloxacin. This case illustrates that previously unrecognized members of the
Mycobacterium smegmatis
group of mycobacteria have pathogenic potential.
Quantification of
Candida albicans
Actin mRNA by the LightCycler System as a Means of Assessing Viability in a Model of Cutaneous Candidiasis
Authors: Okeke Charles N. , Tsuboi Ryoji , Ogawa Hideoki 
Published: July 2002

ABSTRACT

The LightCycler system (two-step reverse transcription-PCR–fluorescent hybridization [LC RT-PCR–FH]) was used to quantify
Candida albicans
actin mRNA as a means of assessing its viability in a reconstituted skin model of cutaneous candidiasis following the application of an antimycotic. A 192-bp
ACT
exon fragment was ligated into the pCR2.1 plasmid vector, and dilutions of the cloned insert (pACT; 4.092 kb) were used as the standard reference template. The LC RT-PCR–FH system could detect 1 fg of pACT, equivalent to 2.2 copies of the plasmid. The
ACT
exon-based PCR primers and FH probes were
C. albicans
specific, and electrophoretic analysis of the LC RT-PCR–FH assay product showed a 174-bp band in agarose gel. The number of copies of
C. albicans ACT
mRNA per milligram of tissue decreased with increasing amounts of amorolfine applied to a
C. albicans
-infected skin model, showing a reduction in viability. Detection and quantification of
ACT
mRNA in tissue by the LC RT-PCR–FH assay corresponded with cultural isolation of
C. albicans
from samples. The
ACT
mRNA-targeted LC RT-PCR–FH assay represents a sensitive, specific, rapid, and quantitative means of assessing the viability of
C. albicans
in infected tissue. This method may also be useful in evaluating the therapeutic efficacies of antifungal drugs in the treatment of various forms of candidiasis and other fungal diseases.
Detection of Antibodies to a Disease-Associated Herpesvirus of the Green Turtle,Chelonia mydas
Authors: Coberley Sadie S. , Herbst Lawrence H. , Brown Daniel R. , Ehrhart Llewellyn M. , Bagley Dean A. , Schaf Susan A. , Moretti Ritchie H. , Jacobson Elliott R. , Klein Paul A. 
Published: July 2002

ABSTRACTLung-eye-trachea disease-associated herpesvirus (LETV) is linked with morbidity and mortality in mariculture-reared green turtles, but its prevalence among and impact on wild marine turtle populations is unknown. An enzyme-linked immunosorbent assay (ELISA) was developed for detection of anti-LETV antibodies and could distinguish LETV-exposed green turtles from those with antibodies to fibropapillomatosis-associated herpesvirus (FPHV). Plasma from two captive-reared green turtles immunized with inactivated LETV served as positive controls. Plasma from 42 healthy captive-reared green turtles and plasma from 30 captive-reared green turtles with experimentally induced fibropapillomatosis (FP) and anti-FPHV antibodies had low ELISA values on LETV antigen. A survey of 19 wild green turtles with and 27 without FP (with and without anti-FPHV antibodies, respectively) identified individuals with antibodies to LETV regardless of their FP status. The seroprevalence of LETV infection was 13%. The presence of antibodies to LETV in plasma samples was confirmed by Western blot and immunohistochemical analyses. These results are the first to suggest that wild Florida green turtles are exposed to LETV or to an antigenically closely related herpesvirus(es) other than FPHV and that FPHV and LETV infections are most likely independent events. This is the first ELISA developed to detect antibodies for a specific herpesvirus infection of marine turtles. The specificity of this ELISA for LETV (ability to distinguish LETV from FPHV) makes it valuable for detecting exposure to this specific herpesvirus and enhances our ability to conduct seroepidemiological studies of these disease-associated agents in marine turtles.
Ehrlichia ruminantium
Major Antigenic Protein Gene (
map1
) Variants Are Not Geographically Constrained and Show No Evidence of Having Evolved under Positive Selection Pressure
Authors: Allsopp M. T. E. P. , Dorfling C. M. , Maillard J. C. , Bensaid A. , Haydon D. T. , van Heerden H. , Allsopp B. A. 
Published: July 2002

ABSTRACT

In a search for tools to distinguish antigenic variants of
Ehrlichia ruminantium
, we sequenced the major antigenic protein genes (
map1
genes) of 21 different isolates and found that the sequence polymorphisms were too great to permit the design of probes which could be used as markers for immunogenicity. Phylogenetic comparison of the 21 deduced MAP1 sequences plus another 9 sequences which had been previously published did not reveal any geographic clustering among the isolates. Maximum likelihood analysis of codon and amino acid changes over the phylogeny provided no statistical evidence that the gene is under positive selection pressure, suggesting that it may not be important for the evasion of host immune responses.
Colonic Infection by
Bilophila wadsworthia
in Pigs
Authors: McOrist Alexandra L. , Warhurst Michelle , McOrist Steven , Bird Anthony R. 
Published: July 2002

ABSTRACT

Bilophila wadsworthia
is a common inhabitant of the human colon and has been associated with appendicitis and other local sites of inflammation in humans. Challenge-exposure or prevalence studies in laboratory and other animals have not been reported.
B. wadsworthia
is closely related phylogenetically to
Desulfovibrio
sp. and
Lawsonia intracellularis
, which are considered colon pathogens. We developed a PCR specific for
B. wadsworthia
DNA. Samples of bacterial DNA extracted from the feces of pigs on six farms in Australia and four farms in Venezuela were examined. Specific DNA of
B. wadsworthia
was detected in the feces of 58 of 161 Australian and 2 of 45 Venezuelan pigs, results comprising 100% of the neonatal pigs, 15% of the weaned grower pigs, and 27% of the adult sows tested. Single-stranded conformational polymorphism analysis of PCR product DNA derived from pigs or from known human strains showed an identical pattern. Histologic examination of the intestines of weaned
B. wadsworthia
-positive pigs found no or minor specific lesions in the small and large intestines, respectively.
B. wadsworthia
is apparently a common infection in neonatal pigs, but its prevalence decreases after weaning. The possible role of
B. wadsworthia
as an infection in animals and in human colons requires further study.
Evidence of Different
Enterocytozoon bieneusi
Genotypes in Patients with and without Human Immunodeficiency Virus Infection
Authors: Liguory Olivier , Sarfati Claudine , Derouin Francis , Molina Jean-Michel 
Published: July 2002

ABSTRACT

We classified 100
Enterocytozoon bieneusi
isolates into five genotypes by a PCR-restriction fragment length polymorphism method. Type I strains were encountered only in human immunodeficiency virus (HIV)-infected patients, whereas type II strains were more frequently found in non-HIV-infected patients (75 versus 10%, respectively;
P
< 10
−4
), suggesting differences in the epidemiology of
E. bieneusi
among these patients.
Genetic Diversity of
Pneumocystis carinii
f. sp.
hominis
Based on Variations in Nucleotide Sequences of Internal Transcribed Spacers of rRNA Genes
Authors: Nimri Laila F. , Moura Iaci N. S. , Huang Laurence , del Rio Carlos , Rimland David , Duchin Jeffrey S. , Dotson Ellen M. , Beard Charles B. 
Published: July 2002

ABSTRACT

A variety of genes have been used to type
Pneumocystis carinii.
In the present study, nucleotide sequence variations in the ITS1 and ITS2 internal transcribed spacer (ITS) regions of the rRNA genes were used to type
Pneumocystis carinii
f. sp.
hominis
DNA obtained from the lungs of 60 human immunodeficiency virus-infected individuals. These regions were amplified by PCR, cloned, and sequenced. Multibase polymorphisms were identified among samples. Several new genotypes are reported on the basis of the nucleotide sequence variations at previously unreported positions of both the ITS1 and the ITS2 regions. Twelve new ITS1 sequences were observed, in addition to the nine sequence types reported previously. The most common was type E, which was observed in 60.5% of the samples. The sequence variations in the ITS1 region were mainly located at positions 5, 12, 23, 24, 45, 53, and 54. Sixteen new ITS2 types were also identified, in addition to the 13 types reported previously. The most common was type g (26.6%). The sequences of the ITS2 regions in most specimens were different from the previously published sequence at bases 120 and 166 through 183. The most common variations observed were deletions at positions 177 through 183. The presence of more than one sequence type in some patients (60%) suggested the occurrence of coinfection with multiple
P. carinii
strains. The genetic polymorphism observed demonstrates the degree of diversity of
Pneumocystis
strains that infect humans. Furthermore, the high degree of polymorphism suggests that these genes are evolving faster than other genes. Consequently, the sequence information derived is useful for purposes such as examination of the potential of person-to-person transmission and recurrent infections but perhaps not for other genotyping applications that rely on more stable genetic loci.
Molecular Identification of
Staphylococcus lugdunensis
in a Patient with Meningitis
Authors: Kaabia N. , Scauarda D. , Lena G. , Drancourt M. 
Published: July 2002

ABSTRACT

A 12-year-old child developed meningitis 6 days after a third ventriculostomy by endoscopy. A coagulase-negative
Staphylococcus
sp. was isolated in pure culture from the cerebrospinal fluid and was definitely identified as
Staphylococcus lugdunensis
after the 16S ribosomal DNA gene and
rpoB
gene were sequenced. This report describes the first case of
S. lugdunensis
meningitis.
Direct Detection of
Helicobacter pylori
Mutations Associated with Macrolide Resistance in Gastric Biopsy Material Taken from Human Immunodeficiency Virus-Infected Subjects
Authors: Scarpellini Paolo , Carrera Paola , Cavallero Annalisa , Cernuschi Massimo , Mezzi Gianni , Testoni Pier Alberto , Zingale Anna , Lazzarin Adriano 
Published: July 2002

ABSTRACT

One hundred forty gastric biopsies were tested by microbiological methods and by amplifying a sequence of 23S rRNA and identifying mutations associated to clarithromycin resistance. Seventy-six specimens were positive for
Helicobacter pylori
. Mutational analysis revealed alterations in 18 (39.1%) of 46 and 2 (8.7%) of 23 samples from human immunodeficiency virus-seropositive and -seronegative persons, respectively. The results of the mutational analysis fully correlated with those of the susceptibility tests.
Infection of Polarized Cultures of Human Intestinal Epithelial Cells with Hepatitis A Virus: Vectorial Release of Progeny Virions through Apical Cellular Membranes
Authors: Blank Christian A. , Anderson David A. , Beard Michael , Lemon Stanley M. 
Published: July 2002

ABSTRACT
Although hepatitis A virus (HAV) is typically transmitted by the fecal-oral route, little is known of its interactions with cells of the gastrointestinal tract. We studied the replication of HAV in polarized cultures of Caco-2 cells, a human cell line which retains many differentiated functions of small intestinal epithelial cells. Virus uptake was 30- to 40-fold more efficient when the inoculum was placed on the apical rather than the basolateral surface of these cells, suggesting a greater abundance of the cellular receptor for HAV on the apical surface. Infection proceeded without cytopathic effect and did not influence transepithelial resistance or the diffusion of inulin across cell monolayers. Nonetheless, there was extensive release of progeny virus, which occurred almost exclusively into apical supernatant fluids (36.4% ± 12.5% of the total virus yield compared with 0.23% ± 0.13% release into basolateral fluids). Brefeldin A caused a profound inhibition of HAV replication, but also selectively reduced apical release of virus. These results indicate that polarized human epithelial cell cultures undergo vectorial infection with HAV and that virus release is largely restricted to the apical membrane. Virus release occurs in the absence of cytopathic effect and may involve cellular vesicular transport mechanisms.
Functional Analysis of the CD4
+
T-Cell Response to Epstein-Barr Virus: T-Cell-Mediated Activation of Resting B Cells and Induction of Viral BZLF1 Expression
Authors: Fu Zheng , Cannon Martin J. 
Published: July 2002

ABSTRACT

In contrast to the major role played by Epstein-Barr virus (EBV)-specific CD8
+
cytotoxic T-cell responses in immunosurveillance, recent studies have offered the apparently paradoxical suggestion that development of EBV-driven human B-cell lymphoproliferative disorders and tumors in SCID/hu mice is dependent on the presence of T cells, in particular CD4
+
T cells. This study presents a functional analysis of the CD4
+
T-cell response to EBV and shows that while CD4
+
T cells may be cytotoxic, they also express Th2 cytokines and CD40 ligand (gp39) and possess B-cell helper function. We show that EBV-specific CD4
+
T cells can provide non-HLA-restricted help for activation of resting B cells via a gp39-CD40-dependent pathway and are able to induce expression of BZLF1, a viral lytic cycle transactivator in latently infected resting B cells, ultimately resulting in rapid outgrowth of transformed B-cell colonies. These results support the proposal that CD4
+
T cells may play a key role in reactivation of latent EBV infection and may thus contribute to the pathogenesis of EBV-driven lymphoproliferative disorders.
The Large Delta Antigen of Hepatitis Delta Virus Potently Inhibits Genomic but Not Antigenomic RNA Synthesis: a Mechanism Enabling Initiation of Viral Replication
Authors: Modahl Lucy E. , Lai Michael M. C. 
Published: July 2002

ABSTRACT
Hepatitis delta virus (HDV) contains two types of hepatitis delta antigens (HDAg) in the virion. The small form (S-HDAg) is required for HDV RNA replication, whereas the large form (L-HDAg) potently inhibits it by a dominant-negative inhibitory mechanism. The sequential appearance of these two forms in the infected cells regulates HDV RNA synthesis during the viral life cycle. However, the presence of almost equal amounts of S-HDAg and L-HDAg in the virion raised a puzzling question concerning how HDV can escape the inhibitory effects of L-HDAg and initiate RNA replication after infection. In this study, we examined the inhibitory effects of L-HDAg on the synthesis of various HDV RNA species. Using an HDV RNA-based transfection approach devoid of any artificial DNA intermediates, we showed that a small amount of L-HDAg is sufficient to inhibit HDV genomic RNA synthesis from the antigenomic RNA template. However, the synthesis of antigenomic RNA, including both the 1.7-kb HDV RNA and the 0.8-kb HDAg mRNA, from the genomic-sense RNA was surprisingly resistant to inhibition by L-HDAg. The synthesis of these RNAs was inhibited only when L-HDAg was in vast excess over S-HDAg. These results explain why HDV genomic RNA can initiate replication after infection even though the incoming viral genome is complexed with equal amounts of L-HDAg and S-HDAg. These results also suggest that the mechanisms of synthesis of genomic versus antigenomic RNA are different. This study thus resolves a puzzling question about the early events of the HDV life cycle.
Attenuated Modified Vaccinia Virus Ankara Can Be Used as an Immunizing Agent under Conditions of Preexisting Immunity to the Vector
Authors: Ramírez Juan C. , Gherardi M. Magdalena , Rodríguez Dolores , Esteban Mariano 
Published: July 2002

ABSTRACTA problem associated with the use of vaccinia virus recombinants as vaccines is the existence of a large human population with preexisting immunity to the vector. Here we showed that after a booster with attenuated recombinant modified vaccinia virus Ankara (rMVA), higher humoral and cellular immune responses to foreign antigens (human immunodeficiency virus type 1 Env and β-galactosidase) were found in mice preimmunized with rMVA than in mice primed with the virulent Western Reserve strain and boosted with rMVA. This enhancement correlated with higher levels of expression of foreign antigens after the booster.