bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the P1 Plasmid Centromere on Expression of P1 Partition Genes
Authors: Hao Jian-Jiang , Yarmolinsky Michael 
Published: October 2002

ABSTRACTThe partition operon of P1 plasmid encodes two proteins, ParA and ParB, required for the faithful segregation of plasmid copies to daughter cells. The operon is followed by a centromere analog,parS, at which ParB binds. ParA, a weak ATPase, represses theparpromoter most effectively in its ADP-bound form. ParB can recruit ParA toparS, stimulate its ATPase, and significantly stimulate the repression. We report here thatparSalso participates in the regulation of expression of thepargenes. A single chromosomalparSwas shown to augment repression of several copies of theparpromoter by severalfold. The repression increase was sensitive to the levels of ParA and ParB and to their ratio. The increase may be attributable to a conformational change in ParA mediated by theparS-ParB complex, possibly acting catalytically. We also observed an inciseffect ofparSwhich enhanced expression ofparB, presumably due to a selective modulation of the mRNA level. Although ParB had been earlier found to spread into and silence genes flankingparS, silencing of theparoperon by ParB spreading was not significant. Based upon analogies between partitioning and septum placement, we speculate that the regulatory switch controlled by theparS-ParB complex might be essential for partitioning itself.
Carbonic Anhydrase Is Essential for Growth of
Ralstonia eutropha
at Ambient CO
2
Concentrations
Authors: Kusian Bernhard , Sültemeyer Dieter , Bowien Botho 
Published: October 2002

ABSTRACT

Mutant strain 25-1 of the facultative chemoautotroph
Ralstonia eutropha
H16 had previously been shown to exhibit an obligately high-CO
2
-requiring (HCR) phenotype. Although the requirement varied with the carbon and energy sources utilized, none of these conditions allowed growth at the air concentration of CO
2
. In the present study, a gene designated
can
and encoding a β-carbonic anhydrase (CA) was identified as the site altered in strain 25-1. The mutation caused a replacement of the highly conserved glycine residue 98 by aspartate in Can. A
can
deletion introduced into wild-type strain H16 generated mutant HB1, which showed the same HCR phenotype as mutant 25-1. Overexpression of
can
in
Escherichia coli
and mass spectrometric determination of CA activity demonstrated that
can
encodes a functional CA. The enzyme is inhibited by ethoxyzolamide and requires 40 mM MgSO
4
for maximal activity. Low but significant CA activities were detected in wild-type H16 but not in mutant HB1, strongly suggesting that the CA activity of Can is essential for growth of the wild type in the presence of low CO
2
concentrations. The HCR phenotype of HB1 was overcome by complementation with heterologous CA genes, indicating that growth of the organism at low CO
2
concentrations requires sufficient CA activity rather than the specific function of Can. The metabolic function(s) depending on CA activity remains to be identified.
Isoprenoid Biosynthesis in
Synechocystis
sp. Strain PCC6803 Is Stimulated by Compounds of the Pentose Phosphate Cycle but Not by Pyruvate or Deoxyxylulose-5-Phosphate
Authors: Ershov Yuri V. , Gantt R. Raymond , Cunningham, Francis X. , Gantt Elisabeth 
Published: October 2002

ABSTRACT

The photosynthetic cyanobacterium
Synechocystis
sp. strain PCC6803 possesses homologs of known genes of the non-mevalonate 2-
C
-methyl-
d
-erythritol 2-phosphate (MEP) pathway for synthesis of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Isoprenoid biosynthesis in extracts of this cyanobacterium, measured by incorporation of radiolabeled IPP, was not stimulated by pyruvate, an initial substrate of the MEP pathway in
Escherichia coli
, or by deoxyxylulose-5-phosphate, the first pathway intermediate in
E. coli
. However, high rates of IPP incorporation were obtained with addition of dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GA3P), as well as a variety of pentose phosphate cycle compounds. Fosmidomycin (at 1 μM and 1 mM), an inhibitor of deoxyxylulose-5-phosphate reductoisomerase, did not significantly inhibit phototrophic growth of the cyanobacterium, nor did it affect [
14
C]IPP incorporation stimulated by DHAP plus GA3P. To date, it has not been possible to unequivocally demonstrate IPP isomerase activity in this cyanobacterium. The combined results suggest that the MEP pathway, as described for
E. coli
, is not the primary path by which isoprenoids are synthesized under photosynthetic conditions in
Synechocystis
sp. strain PCC6803. Our data support alternative routes of entry of pentose phosphate cycle substrates derived from photosynthesis.
Characterization ofbcsAMutations That Bypass Two Distinct Signaling Requirements forMyxococcus xanthusDevelopment
Authors: Cusick John K. , Hager Elizabeth , Gill Ronald E. 
Published: October 2002

ABSTRACTThe BsgA protease is required for starvation-induced development inMyxococcus xanthus.Bypass suppressors of absgAmutant were isolated to identify genes that may encode additional components of BsgA protease-dependent regulation of development. Strain M951 was isolated following Tn5mutagenesis of absgAmutant and was capable of forming fruiting bodies and viable spores in the absence of the BsgA protease. The Tn5Ω951 insertion was localized to a gene,bcsA, that encodes a protein that has significant amino acid similarity to a group of recently described flavin-containing monooxygenases involved in styrene catabolism. Mutations inbcsAbypassed the developmental requirements for both extracellular B and C signaling but did not bypass the requirement for A signaling. Bypass of the B-signaling requirement by thebcsAmutation was accompanied by restored expression of a subset of developmentally inducedlacZfusions to the BsgA protease-deficient strain.bcsAmutant cells developed considerably faster than wild-type cells at low cell density and altered transcriptional levels of a developmentally induced, cell-density-regulated gene (Ω4427), suggesting that thebcsAgene product may normally act to inhibit development in a cell-density-regulated fashion. Bypass of the requirements for both B and C signaling bybcsAmutations suggests a possible link between these two genetically, biochemically, and temporally distinct signaling requirements.
Insufficient Expression of theilv-leuOperon Encoding Enzymes of Branched-Chain Amino Acid Biosynthesis Limits Growth of aBacillus subtilis ccpAMutant
Authors: Ludwig Holger , Meinken Christoph , Matin Anastasija , Stülke Jörg 
Published: October 2002

ABSTRACTBacillus subtilis ccpAmutant strains exhibit two distinct phenotypes: they are defective in catabolite repression, and their growth on minimal media is strongly impaired. This growth defect is largely due to a lack of expression of thegltABoperon. However, growth is impaired even in the presence of glutamate. Here, we demonstrate that theccpAmutant strain needs methionine and the branched-chain amino acids for optimal growth. The control of expression of theilv-leuoperon by CcpA provides a novel regulatory link between carbon and amino acid metabolism.
Transmission of Drug-Resistant Tuberculosis in Texas and Mexico
Authors: Quitugua Teresa N. , Seaworth Barbara J. , Weis Stephen E. , Taylor Jeffery P. , Gillette J. Seb , Rosas Ishmael I. , Jost, Kenneth C. , Magee D. Mitchel , Cox Rebecca A. 
Published: October 2002

ABSTRACT

To examine the transmission of drug-resistant (DR) tuberculosis between Texas and Mexico,
Mycobacterium tuberculosis
isolates resistant to one or more of the first-line antimycobacterial drugs were obtained from 606 patients who resided in Texas and 313 patients who resided in Mexico, primarily within the state of Tamaulipas. The isolates were genotyped by IS
6110
-based restriction fragment length polymorphism (RFLP) analysis and spoligotyping. Of the 919 isolates genotyped, 413 (45%) grouped into 105 clusters containing 2 or more isolates with identical genotypes. In addition to having identical genotypes, identical drug resistance patterns were identified in 250 isolates in 78 clusters (DR clusters). Twenty DR clusters, containing isolates from 32% of the total number of patients infected with DR strains, were geographically distributed across Mexico and Texas. Within this population of 919 patients infected with DR isolates, the probability of being in a DR cluster was the same for residents of Mexico and Texas. In Texas, the significant independent predictors of clustering within DR clusters as opposed to genotype clusters were found to be race, age, country of birth, human immunodeficiency virus (HIV) infection status, and resistance to more than one drug. Specifically, isolates from African Americans, individuals under age 65, individuals born in the United States, and HIV-positive individuals were each more likely to be associated with a DR cluster. By contrast, no significant independent predictors of clustering in a DR cluster were identified in Mexico. Although some DR
M. tuberculosis
strains are geographically restricted, this study suggests that a number of strains are transmitted between Mexico and the United States.
Ca3 Fingerprinting of
Candida albicans
Bloodstream Isolates from the United States, Canada, South America, and Europe Reveals a European Clade
Authors: Pujol Claude , Pfaller Michael , Soll David R. 
Published: October 2002

ABSTRACT

It was previously demonstrated by a cluster analysis that 26 unrelated U.S. isolates of
Candida albicans
separated into three distinct groups (groups I, II, and III) while South African isolates separated into four distinct groups (groups I, II, III, and SA). To verify the absence or underrepresentation of SA isolates in North America, and to identify which groups are represented in Europe and South America, collections of bloodstream isolates from each geographical locale were analyzed by cluster analyses based on genetic fingerprinting with the Ca3 probe. The results verify that North America is almost devoid of SA isolates (2%). However, the results reveal a new clade, designated group E, relatively specific to Europe. While 26% of a European collection of 46 isolates was composed of group E isolates, only 2% of the 164 North American isolates, 5% of 22 South American isolates, and 1% of 361 South African isolates were composed of group E isolates. The North American collection proved to be the least-diverse collection in regard to group representation. In a comparison of collections from the Northeast, Midwest, and Southwest regions of the United States, Canada, and South America, it was demonstrated that both the U.S. Southwest and the South American collections were devoid of group II isolates. Together these results identify for the first time a European-specific clade and demonstrate clear distinctions in the representations of the five demonstrated clades (groups I, II, III, SA, and E) in different geographical locales.
Alveolar Echinococcosis: Characterization of Diagnostic Antigen Em18 and Serological Evaluation of Recombinant Em18
Authors: Sako Yasuhito , Nakao Minoru , Nakaya Kazuhiro , Yamasaki Hiroshi , Gottstein Bruno , Lightowers Marshall W. , Schantz Peter M. , Ito Akira 
Published: October 2002

ABSTRACT

The
Echinococcus multilocularis
protein Em18 is one of the most promising antigens for use in serodiagnosis of alveolar echinococcosis in human patients. Here we identify an antigenic relationship between Em18 and a 65-kDa immunodominant
E. multilocularis
surface protein previously identified as either EM10 or EmII/3. The NH
2
-terminal sequence of native Em18 was determined, revealing it to be a fragment of EM10. Experiments were undertaken to investigate the effect of proteinase inhibitors on the degradation of EM10 in crude extracts of
E. multilocularis
protoscoleces. Em18 was found to be the product of degradation of EM10 by cysteine proteinase. A recombinant Em18 (RecEm18, derived from
349
K to
508
K of EM10) was successfully expressed by using
Escherichia coli
expression system and then evaluated for use in serodiagnosis of alveolar echinococcosis. RecEm18 was recognized by 27 (87.1%) and 28 (90.3%) of 31 serum samples from clinically and/or pathologically confirmed alveolar echinococcosis patients by enzyme-linked immunosorbent assay and immunoblotting, respectively. Of 33 serum samples from cystic echinococcosis patients, 1 was recorded as having a weak positive reaction to RecEm18; however, none of the serum samples which were tested from neurocysticercosis patients (
n
= 10) or healthy people (
n
= 15) showed positive reactions. RecEm18 has the potential for use in the differential serodiagnosis of alveolar echinococcosis.
Genetic Analysis of
Pseudomonas aeruginosa
Isolates from the Sputa of Australian Adult Cystic Fibrosis Patients
Authors: Anthony Mario , Rose Barbara , Pegler Mary Beard , Elkins Mark , Service Helen , Thamotharampillai Keerthi , Watson Jason , Robinson Michael , Bye Peter , Merlino John , Harbour Colin 
Published: October 2002

ABSTRACT

Genetic investigations were carried out with 50 phenotypically selected strains of
Pseudomonas aeruginosa
from 18 patients attending an Australian cystic fibrosis (CF) center. The isolates were analyzed by restriction fragment length polymorphism (RFLP) analysis by pulsed-field gel electrophoresis (PFGE). Phylogenetic analysis of the macrorestriction patterns showed rates of genetic similarity ranging from 76 to 100%; 24 (48%) of the strains from 11 patients had greater than 90% similarity. A dominant strain emerged: 15 isolates from seven patients had identical PFGE patterns, and 4 other isolates were very closely related. The 50 isolates were grouped into 21 pulsotypes on the basis of visual delineation of a three-band difference. Ten of the 18 (56%) patients were infected with clonal or subclonal strains. Sequence analysis of PCR products derived from the
mucA
gene showed 20 mutations, with the number of mutations in individual isolates ranging from 1 to 4; 19 of these changes are reported here for the first time. Potentially functional changes were found in 22 (44%) isolates. Eight changes (five transversions and three single base deletions) led to premature stop codons, providing support for the presence of
mucA
mutations as one pathway to mucoidy. There was a trend toward an association between the dominant strain and lack of potentially functional
mucA
mutations (
P
= 0.09 by the χ
2
test) but no relationship between genotype and phenotype. This is the first study of genetic variation in
P. aeruginosa
isolates from adult Australian CF patients. The findings highlight the need for further investigations on the transmissibility of
P. aeruginosa
in CF patients.
Combined Use of Two Genetic Fingerprinting Methods, Pulsed-Field Gel Electrophoresis and Ribotyping, for Characterization of
Escherichia coli
O157 Isolates from Food Animals, Retail Meats, and Cases of Human Disease
Authors: Avery S. M. , Liebana E. , Reid C.-A. , Woodward M. J. , Buncic S. 
Published: October 2002

ABSTRACT

Two genetic fingerprinting techniques, pulsed-field gel electrophoresis (PFGE) and ribotyping, were used to characterize 207
Escherichia coli
O157 isolates from food animals, foods of animal origin, and cases of human disease (206 of the isolates were from the United Kingdom). In addition, 164 of these isolates were also phage typed. The isolates were divided into two general groups: (i) unrelated isolates not known to be epidemiologically linked (
n
= 154) and originating from food animals, foods and the environment, or humans and (ii) epidemiologically related isolates (
n
= 53) comprised of four related groups (RGs) originating either from one farm plus the abattoir where cattle from that farm were slaughtered or from one of three different English abattoirs. PFGE was conducted with the restriction endonuclease
Xba
I, while for ribotyping, two restriction endonucleases (
Pst
I and
Sph
I) were combined to digest genomic DNAs simultaneously. The 207
E. coli
O157 isolates produced 97 PFGE profiles and 51 ribotypes. The two genetic fingerprinting methods had similar powers to discriminate the 154 epidemiologically unrelated
E. coli
O157 isolates in the study (Simpson's index of diversity [
D
] = 0.98 and 0.94 for PFGE typing and ribotyping, respectively). There was no correlation between the source of an isolate (healthy meat or milk animals, retail meats, or cases of human infection) and either particular PFGE or ribotype profiles or clusters. Combination of the results of both genetic fingerprinting methods produced 146 types, significantly more than when either of the two methods was used individually. Consequently, the superior discriminatory performance of the PFGE-ribotyping combination was proven in two ways: (i) by demonstrating that the majority of the
E. coli
O157 isolates with unrelated histories were indeed distinguishable types and (ii) by identifying some clonal groups among two of the four RGs of
E. coli
O157 isolates (comprising PFGE types different by just one or two bands), the relatedness of which would have remained unconfirmed otherwise.
Nasopharyngeal Carriage of Potential Bacterial Pathogens Related to Day Care Attendance, with Special Reference to the Molecular Epidemiology of
Haemophilus influenzae
Authors: Peerbooms Paul G. H. , Engelen Marlene N. , Stokman Dominique A. J. , van Benthem Birgit H. B. , van Weert Maria-Lucia , Bruisten Sylvia M. , van Belkum Alex , Coutinho Roel A. 
Published: October 2002

ABSTRACT

Nasopharyngeal carriage of
Haemophilus influenzae
,
Streptococcus pneumoniae
, and
Moraxella catarrhalis
was studied in 259 children attending day care centers (DCC) in Amsterdam, The Netherlands, and in 276 control children. The DCC children were sampled a second time after 4 weeks. Carriage rates for DCC children and controls were 58 and 37% for
S. pneumoniae
, 37 and 11% for
H. influenzae
, and 80 and 48% for
M. catarrhalis
, respectively. No increased antibiotic resistance rates were found in strains isolated from DCC children. All
H. influenzae
isolates were typed by random amplified polymorphic DNA (RAPD) analysis. Evidence for frequent transmission of
H. influenzae
strains within DCC was found. In the control group only two isolates (4%) displayed identical RAPD types versus 38% of strains from DCC children. Colonization with
H. influenzae
appeared to be short-lived in these children; more than half of the children harboring
H. influenzae
in the first sample were negative in the second sample, whereas most children still positive in the second sample had a different genotype than in the first sample. Of the newly acquired strains in the second sample, 40% were identical to a strain that had been found in a child in the same DCC in the first sample. DCC are to be considered epidemiological niches with a high potential for the spread of pathogenic microorganisms.
Analysis of Phylogenetic Relationship of
Cylindrocarpon lichenicola
and
Acremonium falciforme
to the
Fusarium solani
Species Complex and a Review of Similarities in the Spectrum of Opportunistic Infections Caused by These Fungi
Authors: Summerbell R. C. , Schroers H.-J. 
Published: October 2002

ABSTRACT

An emerging pattern of similarity in medical case reports led to a project to compare the phylogenetic affinities of two well-known tropical fungal opportunistic pathogens,
Cylindrocarpon lichenicola
and
Acremonium falciforme
, to members of the
Fusarium solani
species complex.
C. lichenicola
and
A. falciforme
, despite their deviating conidial morphologies, were shown via sequencing of the ribosomal large subunit to be well instituted within a clade mainly consisting of typical
F. solani
strains and other species until recently considered variants of
F. solani
. The original name
Fusarium lichenicola
C. B. Massalongo is reestablished, and the new combination
F. falciforme
is made. Recognition of these species as fusaria is necessary for correct interpretation of current and future molecular diagnostic tests. Reevaluation of species morphology in light of the molecular findings showed that certain features, especially elongate filiform conidiophores with integrated terminal phialides, facilitate correct microscopic classification of these atypical
Fusarium
species. There is a strong and underrecognized overlap in the spectra of cases caused by members of the
F. solani
clade, particularly ocular infections, mycetomas, and, in the neutropenic host, disseminated and other serious systemic infections. A novel synthesis of case reports shows that patients from areas with warm climates may develop a distinctive fusarial intertrigo caused by
F. solani
,
Fusarium lichenicola
, or
Fusarium oxysporum
.
Comparison of the Etest and the Sensititre Colorimetric Methods with the NCCLS Proposed Standard for Antifungal Susceptibility Testing of
Aspergillus
Species
Authors: Meletiadis Joseph , Mouton Johan W. , Meis Jacques F. G. M. , Bouman Bianca A. , Verweij Paul E. 
Published: October 2002

ABSTRACT

The susceptibilities of 25 clinical isolates of
Aspergillus fumigatus
,
A. flavus
,
A. terreus
,
A. nidulans
, and
A. ustus
to itraconazole and amphotericin B were determined by an agar diffusion-dilution method (the Etest method) and a colorimetric broth microdilution method (the Sensititre method); and the results were compared with those obtained by the NCCLS proposed standard M-38P method for antifungal susceptibility testing of filamentous fungi. Various MIC endpoints for the three methods were determined visually by four different observers in three blinded experiments, and the reproducibilities among the observers (interobserver agreement) and among the replicates (interexperimental agreement) as well as the levels of agreement between the NCCLS, the Etest, and the Sensititre methods were calculated. High levels of reproducibility (within 1 twofold dilution) were found for the NCCLS method (>95%) with the MIC-0 endpoint (complete inhibition of growth) for both drugs and with the MIC-1 endpoint (slight growth) for itraconazole and for the Sensititre method (>90%) with all MIC endpoints, although for the latter the interexperimental agreement for itraconazole was comparatively lower (83 to 93%). The Etest method was less reproducible (67 to 87%) for both drugs. Using the recommended MIC endpoints, high levels of agreement (within one twofold dilution) between the NCCLS and the Sensititre methods for all species were found for amphotericin B (>77%) but not for itraconazole (<66%), for which the MICs by the Sensititre method were up to 3 twofold dilutions lower than the corresponding MICs by the NCCLS method. The use of the first blue well as an endpoint for the Sensititre method and 48 h of incubation improved the levels of agreement with the NCCLS method. Low levels of agreement between the NCCLS and the Etest methods using the recommended MIC endpoints were found for most species, especially after 48 h of incubation (<50%), when the MICs obtained by the Etest method were up to 9 twofold dilutions higher than the corresponding MICs obtained by the NCCLS method. Relatively better agreement was found after 24 h, although it was species dependent, with the highest levels of agreement (>82%) found for
A. terreus
and
A. ustus
for amphotericin B and
A. fumigatus
for both drugs. Overall, better agreement was found when MIC-0 was used as the MIC endpoint for the NCCLS method for both drugs and when the MICs by the Etest method were determined after 48 h of incubation for itraconazole and after 24 h of incubation for amphotericin B.