bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fate ofEntamoeba histolyticaduring Establishment of Amoebic Liver Abscess Analyzed by Quantitative Radioimaging and Histology
Authors: Rigothier Marie-Christine , Khun Hout , Tavares Paulo , Cardona Ana , Huerre Michel , Guillén Nancy 
Published: July 2002

ABSTRACTThe protozoan parasiteEntamoeba histolyticais the causative agent of amoebiasis, a human disease characterized by dysentery and liver abscess. The physiopathology of hepatic lesions can be satisfactorily reproduced in the hamster animal model by the administration of trophozoites through the portal vein route. Hamsters were infected with radioactively labeled amoebas for analysis of liver abscess establishment and progression. The radioimaging of material from parasite origin and quantification of the number inflammation foci, with or without amoebas, described here provides the first detailed assessment of trophozoite survival and death during liver infection byE. histolytica. The massive death of trophozoites observed in the first hours postinfection correlates with the presence of a majority of inflammatory foci without parasites. A critical point for success of infection is reached after 12 h when the lowest number of trophozoites is observed. The process then enters a commitment phase during which parasites multiply and the size of the infection foci increases fast. The liver shows extensive areas of dead hepatocytes that are surrounded by a peripheral layer of parasites facing inflammatory cells leading to acute inflammation. Our results show that the host response promotes massive parasite death but also suggest also that this is a major contributor to the establishment of inflammation during development of liver abscess.
Restart of Exponential Growth of Cold-Shocked
Yersinia enterocolitica
Occurs after Down-Regulation of
cspA1/A2
mRNA
Authors: Neuhaus Klaus , Rapposch Sonja , Francis Kevin P. , Scherer Siegfried 
Published: July 2002

ABSTRACT

The cellular content of major cold shock protein (MCSP) mRNA transcribed from the tandem gene duplication
cspA1/A2
and growth of
Yersinia enterocolitica
were compared when exponentially growing cultures of this bacterium were cold shocked from 30 to 20, 15, 10, 5, or 0°C, respectively. A clear correlation between the time point when exponential growth resumes after cold shock and the degradation of
cspA1/A2
mRNA was found. A polynucleotide phosphorylase-deficient mutant was unable to degrade
cspA1/A2
mRNA properly and showed a delay, as well as a lower rate, of growth after cold shock. For this mutant, a correlation between decreasing
cspA1/A2
mRNA and restart of growth after cold shock was also observed. For both wild-type and mutant cells, no correlation of restart of growth with the cellular content of MCSPs was found. We suggest that, after synthesis of cold shock proteins and cold adaptation of the cells, MCSP mRNAs must be degraded; otherwise, they trap ribosomes, prevent translation of bulk mRNA, and thus inhibit growth of this bacterium at low temperatures.
Footprinting Studies of Specific Complexes Formed by RepA, a Replication Initiator of Plasmid pCU1, and Its Binding Site
Authors: Papp Péter Pál , Élö Péter , Semsey Szabolcs , Orosz László 
Published: July 2002

ABSTRACT

The basic replicon of plasmid pCU1 contains three different replication origins. Replication initiated from the
oriB
origin requires pCU1-encoded protein RepA. Previously, information analysis of 19 natural RepA binding sequences predicted a 20-bp sequence as a RepA binding site. Guanines contacting RepA in the major groove of DNA have also been determined. In this study, we used the missing-nucleoside method to determine all of the bases relevant to RepA binding. The importance of some thymine bases was also confirmed by a missing-thymine site interference assay. Participation of the 5-methyl groups of two thymines (at positions −6 and 7) in RepA binding was pointed out by a missing-thymine methyl site interference assay. Phosphate groups of the DNA backbone which strongly interfered with RepA binding upon ethylation were also identified. The pattern of contacting positions mapped by hydroxyl radical protection footprinting indicates that RepA binds to one face of B-form DNA. The length of the binding site was found to be 20 bp by dissociation rate measurement of complexes formed between RepA and a variety of binding sequences. The symmetry of the binding site and that of the contacting bases, particularly the reacting 5-methyl groups of two thymines, suggest that pCU1-encoded RepA may contact its site as a homodimer.
Isolation of the
MIG1
Gene from
Candida albicans
and Effects of Its Disruption on Catabolite Repression
Authors: Zaragoza Oscar , Rodríguez Cristina , Gancedo Carlos 
Published: July 2002

ABSTRACT

We have cloned a
Candida albicans
gene (
CaMIG1
) that encodes a protein homologous to the DNA-binding protein Mig1 from
Saccharomyces cerevisiae
(
Sc
Mig1). The
C. albicans
Mig1 protein (
Ca
Mig1) differs from
Sc
Mig1, in that, among other things, it lacks a putative phosphorylation site for Snf1 and presents several long stretches rich in glutamine or in asparagine, serine, and threonine and has the effector domain located at some distance (50 amino acids) from the carboxy terminus. Expression of
CaMIG1
was low and was similar in glucose-, sucrose-, or ethanol-containing media. Disruption of the two
CaMIG1
genomic copies had no effect in filamentation or infectivity. Levels of a glucose-repressible α-glucosidase, implicated in both sucrose and maltose utilization, were similar in wild-type or
mig1/mig1
cells. Disruption of
CaMIG1
had also no effect on the expression of the glucose-repressed gene
CaGAL1. CaMIG1
was functional in
S. cerevisiae
, as judged by its ability to suppress the phenotypes produced by
mig1
or
tps1
mutations. In addition,
Ca
Mig1 formed specific complexes with the URS1 region of the
S. cerevisiae FBP1
gene. The existence of a possible functional analogue of
CaMIG1
in
C. albicans
was suggested by the results of band shift experiments.
Cloning, Expression, and Purification of a Thermostable Nonhomodimeric Restriction Enzyme,
Bsl
I
Authors: Hsieh Pei-chung , Xiao Jian-ping , O'loane Diana , Xu Shuang-yong 
Published: July 2002

ABSTRACT

Bsl
I is a thermostable type II restriction endonuclease with interrupted recognition sequence CCNNNNN/NNGG (/, cleavage position). The
Bsl
I restriction-modification system from
Bacillus
species was cloned and expressed in
Escherichia coli
. The system is encoded by three genes: the 2,739-bp
Bsl
I methylase gene (
bslIM
), the
bslIR
α gene, and the
bslIR
β gene. The α and β subunits of
Bsl
I can be expressed independently in
E. coli
in the absence of
Bsl
I methylase (M.
Bsl
I) protection.
Bsl
I endonuclease activity can be reconstituted in vitro by mixing the two subunits together. Gel filtration chromatography and native polyacrylamide gel electrophoresis indicated that
Bsl
I forms heterodimers (αβ), heterotetramers (α
2
β
2
), and possibly oligomers in solution. Two β subunits can be cross-linked by a chemical cross-linking agent, indicating formation of heterotetramer
Bsl
I complex (α
2
β
2
). In DNA mobility shift assays, neither subunit alone can bind DNA. DNA mobility shift activity was detected after mixing the two subunits together. Because of the symmetric recognition sequence of the
Bsl
I endonuclease, we propose that its active form is α
2
β
2
. M.
Bsl
I contains nine conserved motifs of N-4 cytosine DNA methylases within the β group of aminomethyltransferase. Synthetic duplex deoxyoligonucleotides containing cytosine hemimethylated or fully methylated at N-4 in
Bsl
I sites in the first or second cytosine are resistant to
Bsl
I digestion. C-5 methylation of the second cytosine on both strands within the recognition sequence also renders the site refractory to
Bsl
I digestion. Two putative zinc fingers are found in the α subunit of
Bsl
I endonuclease.
Dimers of π Protein Bind the A+T-Rich Region of the R6K γ Origin near the Leading-Strand Synthesis Start Sites: Regulatory Implications
Authors: Krüger Ricardo , Filutowicz Marcin 
Published: July 2002

ABSTRACT
The replication of γ origin, a minimal replicon derived from plasmid R6K, is controlled by the Rep protein π. At low intracellular concentrations, π activates the γ origin, while it inhibits replication at elevated concentrations. Additionally, π acts as a transcription factor (auto)repressing its own synthesis. These varied regulatory functions depend on π binding to reiterated DNA sequences bearing a TGAGNG motif. However, π also binds to a “non-iteron” site (i.e., not TGAGNG) that resides in the A+T-rich region adjacent to the iterons. This positioning places the non-iteron site near the start sites for leading-strand synthesis that also occur in the A+T-rich region of γ origin. We have hypothesized that origin activation (at low π levels) would require the binding of π monomers to iterons, while the binding of π dimers to the non-iteron site (at high π levels) would be required to inhibit priming. Although monomers as well as dimers can bind to an iteron, we demonstrate that only dimers bind to the non-iteron site. Two additional pieces of data support the hypothesis of negative replication control by π binding to the non-iteron site. First, π binds to the non-iteron site about eight times less well than it binds to a single iteron. Second, hyperactive variants of π protein (called copy-up) either do not bind to the non-iteron site or bind to it less well than wild-type π. We propose a replication control mechanism whereby π would directly inhibit primer formation.
Proteome Analysis of Metabolically Engineered
Escherichia coli
Producing Poly(3-Hydroxybutyrate)
Authors: Han Mee-Jung , Yoon Sang Sun , Lee Sang Yup 
Published: July 2002

ABSTRACT

Recombinant
Escherichia coli
strains harboring heterologous polyhydroxyalkanoate (PHA) biosynthesis genes were shown to accumulate unusually large amounts of PHA. In the present study, integrated cellular responses of metabolically engineered
E. coli
to the accumulation of poly(3-hydroxybutyrate) (PHB) in the early stationary phase were analyzed at the protein level by two-dimensional gel electrophoresis. Out of 20 proteins showing altered expression levels with the accumulation of PHB, 13 proteins were identified with the aid of mass spectrometry. Three heat shock proteins, GroEL, GroES, and DnaK, were significantly up-regulated in PHB-accumulating cells. Proteins which play essential roles in protein biosynthesis were unfavorably influenced by the accumulation of PHB. Cellular demand for the large amount of acetyl coenzyme A and NADPH for the PHB biosynthesis resulted in the increased synthesis of two enzymes of the glycolytic pathway and one enzyme of the Entner-Doudoroff pathway. The expression of the
yfiD
gene encoding a 14.3-kDa protein, which is known to be produced at low pH, was greatly induced with the accumulation of PHB. Therefore, it could be concluded that the accumulation of PHB in
E. coli
acted as a stress on the cells, which reduced the cells' ability to synthesize proteins and induced the expression of various protective proteins.
Identification of Two
prpDBC
Gene Clusters in
Corynebacterium glutamicum
and Their Involvement in Propionate Degradation via the 2-Methylcitrate Cycle
Authors: Claes Wilfried A. , Pühler Alfred , Kalinowski Jörn 
Published: July 2002

ABSTRACT

Genome sequencing revealed that the
Corynebacterium glutamicum
genome contained, besides
gltA
, two additional citrate synthase homologous genes (
prpC
) located in two different
prpDBC
gene clusters, which were designated
prpD1B1C1
and
prpD2B2C2
. The coding regions of the two gene clusters as well as the predicted gene products showed sequence identities of about 70 to 80%. Significant sequence similarities were found also to the
prpBCDE
operons of
Escherichia coli
and
Salmonella enterica
, which are known to encode enzymes of the propionate-degrading 2-methylcitrate pathway. Homologous and heterologous overexpression of the
C. glutamicum prpC1
and
prpC2
genes revealed that their gene products were active as citrate synthases and 2-methylcitrate synthases. Growth tests showed that
C. glutamicum
used propionate as a single or partial carbon source, although the beginning of the exponential growth phase was strongly delayed by propionate for up to 7 days. Compared to growth on acetate, the specific 2-methylcitrate synthase activity increased about 50-fold when propionate was provided as the sole carbon source, suggesting that in
C. glutamicum
the oxidation of propionate to pyruvate occurred via the 2-methylcitrate pathway. Additionally, two-dimensional gel electrophoresis experiments combined with mass spectrometry showed strong induction of the expression of the
C. glutamicum prpD2B2C2
genes by propionate as an additional carbon source. Mutational analyses revealed that only the
prpD2B2C2
genes were essential for the growth of
C. glutamicum
on propionate as a sole carbon source, while the function of the
prpD1B1C1
genes remains obscure.
Effects of
rodA
and
pbp2b
Disruption on Cell Morphology and Oxidative Stress Response of
Streptococcus thermophilus
CNRZ368
Authors: Thibessard Annabelle , Fernandez Annabelle , Gintz Brigitte , Leblond-Bourget Nathalie , Decaris Bernard 
Published: July 2002

ABSTRACT

Insertional mutagenesis was used to isolate clones from
Streptococcus thermophilus
CNRZ368 that were modified in their abilities to tolerate oxidative stress. During this process, two menadione-sensitive clones (6G4 and 18C3) were found to display abnormal cell morphologies and distorted chain topologies and were further studied. Molecular characterization of both 6G4 and 18C3 mutants indicated that they were disrupted in open reading frames homologous to
rodA
and
pbp2b
, respectively. Both genes encoded proteins in
Escherichia coli
that were described as being implicated in peptidoglycan synthesis during the process of cell elongation and to function in determining the rod shape of the cell. This work reports a possible connection between peptidoglycan biosynthesis and oxidative stress defense in
S. thermophilus
CNRZ368.
Oxidative-Stress Resistance Mutants ofHelicobacter pylori
Authors: Olczak Adriana A. , Olson Jonathan W. , Maier Robert J. 
Published: July 2002

ABSTRACTWithin a large family of peroxidases, one member that catalyzes the reduction of organic peroxides to alcohols is known as alkyl hydroperoxide reductase, or AhpC. Gene disruption mutations in the gene encoding AhpC ofHelicobacter pylori(ahpC) were generated by screening transformants under low-oxygen conditions. Two classes of mutants were obtained. Both types lack AhpC protein, but the major class (type I) isolated was found to synthesize increased levels (five times more than the wild type) of another proposed antioxidant protein, an iron-binding, neutrophil-activating protein (NapA). The other class of mutants, the minor class (type II), produced wild-type levels of NapA. The two types of AhpC mutants differed in their frequencies of spontaneous mutation to rifampin resistance and in their sensitivities to oxidative-stress chemicals, with the type I mutants exhibiting less sensitivity to organic hydroperoxides as well as having a lower mutation frequency. ThenapApromoter regions of the two types of AhpC mutants were identical, and primer extension analysis revealed their transcription start site to be the same as for the wild type. Gene disruption mutations were obtained innapAalone, and a double mutant strain (ahpC napA) was also created. All four of the oxidative-stress resistance mutants could be distinguished from the wild type in oxygen sensitivity or in some other oxidative-stress resistance phenotype (i.e., in sensitivity to stress-related chemicals and spontaneous mutation frequency). For example, growth of the NapA mutant was more sensitive to oxygen than that of the wild-type strain and both of the AhpC-type mutants were highly sensitive to paraquat and to cumene hydroperoxide. Of the four types of mutants, the double mutant was the most sensitive to growth inhibition by oxygen and by organic peroxides and it had the highest spontaneous mutation frequency. Notably, two-dimensional gel electrophoresis combined with protein sequence analysis identified another possible oxidative-stress resistance protein (HP0630) that was up-regulated in the double mutant. However, the transcription start site of the HP0630 gene was the same for the double mutant as for the wild type. It appears thatH. pylorican readily modulate the expression of other resistance factors as a compensatory response to loss of a major oxidative-stress resistance component.
Mycobacterium microti
Llama-Type Infection Presenting as Pulmonary Tuberculosis in a Human Immunodeficiency Virus-Positive Patient
Authors: Horstkotte Matthias A. , Sobottka Ingo , Schewe Carl K. , Schäfer Peter , Laufs Rainer , Rüsch-Gerdes Sabine , Niemann Stefan 
Published: July 2002

ABSTRACT

A rare case of
Mycobacterium microti
infection in a human immunodeficiency virus-positive patient is described. Because of unusual morphological and cultural features, the pathogen was analyzed by spoligotyping and identified as the
Mycobacterium microti
llama type. Although culture of
M. microti
is difficult, drug susceptibility testing could be performed, which correlated with the clinical outcome.
Evaluation of a Rapid Immunochromatographic Test for Detection of
Streptococcus pneumoniae
Antigen in Urine Samples from Adults with Community-Acquired Pneumonia
Authors: Murdoch David R. , Laing Richard T. R. , Mills Graham D. , Karalus Noel C. , Town G. Ian , Mirrett Stanley , Reller L. Barth 
Published: July 2002

ABSTRACT

Streptococcus pneumoniae
is the most common cause of community-acquired pneumonia but is undoubtedly underdiagnosed. Isolation of
S. pneumoniae
from blood is specific but lacks sensitivity, while isolation of
S. pneumoniae
from sputum may represent colonization. We evaluated a new immunochromatographic test (NOW
S. pneumoniae
urinary antigen test; Binax, Portland, Maine) that is simple to perform and that can detect
S. pneumoniae
antigen in urine within 15 min. Urine samples from 420 adults with community-acquired pneumonia and 169 control patients who did not have pneumonia were tested. Urine from 315 (75%) of the pneumonia patients and all controls was tested both before and after 25-fold concentration, while the remaining 105 samples were only tested without concentration.
S. pneumoniae
urinary antigen tests were positive for 120 (29%) patients with pneumonia and for none of the controls. Of the urine samples tested with and without concentration, 96 were positive, of which 6 were positive only after concentration.
S. pneumoniae
antigen was detected in the urine from 16 of the 20 (80%) patients with blood cultures positive for
S. pneumoniae
and from 28 of the 54 (52%) patients with sputum cultures positive for
S. pneumoniae
. The absence of
S. pneumoniae
antigen in the urine from controls suggests that the specificity is high. Concentration of urine prior to testing resulted in a small increase in yield. The NOW
S. pneumoniae
urinary antigen test should be a useful adjunct to culture for determining the etiology of community-acquired pneumonia in adults.
Plasmid-BornesmrGene Causes Resistance to Quaternary Ammonium Compounds in BovineStaphylococcus aureus
Authors: Bjorland Jostein , Sunde Marianne , Waage Steinar 
Published: July 2002

ABSTRACTResistance to quaternary ammonium compounds (QAC) in staphylococci is common in hospital environments and has been described in the food industry. Little is known about staphylococcal QAC resistance associated with animal disease, although such disinfectants are widely used in veterinary medicine. In order to investigate the occurrence of QAC resistance in staphylococci isolated from QAC-exposed animals, 32 penicillin- and tetracycline-resistant and 23 penicillin- and tetracycline-susceptibleStaphylococcus aureusisolates collected from milk from cows with mastitis during a 4-year period were selected for QAC susceptibility studies and genetic characterization. The isolates originated from four different herds that used a common pasture with a joint milking parlor in the summer. During the pasture season, a teat cream containing the QAC cetyltrimethylammonium bromide had been used daily for more than 10 years for mastitis control. Three of the penicillin- and tetracycline-resistant isolates, which were recovered from three different cows during a 20-month period, were resistant to QAC. Plasmid analysis, PCR, and DNA sequencing revealed a novel plasmid of 2,239 bp containing thesmrgene. The plasmid, designated pNVH99, has similarities to small,smr-containing staphylococcal plasmids previously found in human and food isolates. pNVH99 is a new member of the pC194 family of rolling-circle replication plasmids. The three QAC-resistant isolates, as well as 28 of the 29 remaining penicillin- and tetracycline-resistant isolates, were indistinguishable by pulsed-field gel electrophoresis. The study indicates that the occurrence and spread of QAC-resistantS. aureusamong dairy cows may be a problem that needs further investigation.
Pulsed-Field Gel Electrophoresis in Differentiation of
Erysipelothrix
Species Strains
Authors: Okatani Alexandre Tomomitsu , Uto Takehiko , Taniguchi Takahide , Horisaka Tomoko , Horikita Tetsuya , Kaneko Ken-Ichi , Hayashidani Hideki 
Published: July 2002

ABSTRACT

We report here the first analysis of
Erysipelothrix
spp. using pulsed-field gel electrophoresis (PFGE). Seventy strains of
Erysipelothrix
spp. were analyzed.
Sma
I,
Asc
I, and
Not
I were tested for the ability to cleave the DNA extracted from those strains, and among them,
Sma
I was the most reliable enzyme. Sixty-three distinct PFGE patterns were produced, and no DNA degradation was observed, allowing the identification of all of the strains. Based on these results and on those of a previous analysis using randomly amplified polymorphic DNA and ribotyping, PFGE with
Sma
I might be considered to be more sensitive than those methods and to be the best method for epidemiological studies of strains of this genus.
Burden of Unidentifiable Mycobacteria in a Reference Laboratory
Authors: Tortoli Enrico , Bartoloni Alessandro , Böttger Erik C. , Emler Stefan , Garzelli Carlo , Magliano Enrico , Mantella Antonia , Rastogi Nalin , Rindi Laura , Scarparo Claudio , Urbano Pasquale 
Published: July 2002

ABSTRACT

Modern identification techniques at the genomic level have greatly improved the taxonomic knowledge of mycobacteria. In adjunct to nucleic acid sequences, mycobacterial identification has been endorsed by investigation of the lipidic patterns of unique mycolic acids in such organisms. In the present investigation, the routine use of high-performance liquid chromatography (HPLC) of mycolic acids, followed by the sequencing of the 16S rRNA, allowed us to select 72 mycobacterial strains, out of 1,035 screened, that do not belong to any of the officially recognized mycobacterial species. Most strains (i.e., 47) were isolated from humans, 13 were from the environment, 3 were from animals, and 9 were from unknown sources. The majority of human isolates were grown from the respiratory tract and were therefore most likely not clinically significant. Some, however, were isolated from sterile sites (blood, pleural biopsy, central venous catheter, or pus). Many isolates, including several clusters of two or more strains, mostly slow growers and scotochromogenic, presented unique genetic and lipidic features. We hope the data reported here, including the results of major conventional identification tests, the HPLC profiles of strains isolated several times, and the whole sequences of the 16S rRNA hypervariable regions of all 72 mycobacteria, may encourage reporting of new cases. The taxonomy of the genus
Mycobacterium
is, in our opinion, still far from being fully elucidated, and the reporting of unusual strains provides the best background for the recognition of new species. Our report also shows the usefulness of the integration of novel technology to routine diagnosis, especially in cases involving slow-growing microorganisms such as mycobacteria.