bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival Response and Rearrangement of Plasmid DNA of
Lactococcus lactis
during Long-Term Starvation
Authors: Kim Woojin S. , Park Ji Hyeon , Ren Jun , Su Ping , Dunn Noel W. 
Published: July 2002

ABSTRACT

The survival response of
Lactococcus lactis
during long-term starvation was investigated. The cells were cultured with different levels of glucose (the sole energy source) and either were kept in the resultant spent medium or transferred to fresh medium (without glucose) for up to 2 years. The survival of the cells during starvation was not dependent on the nature of transition phase, as expected, but on the nature of medium in which the cells were kept. The proliferation of cells, despite the apparent lack of glucose, could have been due to some cells being able to utilize the small amounts of peptides still present in the spent medium or to use energy sources provided by the breakup of dead cells. The 1- and 2-year-old cultures contained cells with vastly changed morphotypes. When these isolates were examined, it was revealed that the original plasmids present in the parent were rearranged in a certain way, and an entirely new plasmid was generated. Changes were also evident in the chromosomal DNA and in gene expression. Furthermore, all of the isolates exhibited a growth advantage relative to the parent cells when grown in energy-limiting media. When they were tested against different types of stresses, they exhibited a higher resistance against the bile salt and hydrogen peroxide stresses compared to the parent. Because of the similar changes observed in the 2-year-old isolates, a similar survival strategy may be operational in those cells that survive for that length of time.
Novel
psbA1
Gene from a Naturally Occurring Atrazine-Resistant Cyanobacterial Isolate
Authors: Sajjaphan Kannika , Shapir Nir , Judd Adam K. , Wackett Lawrence P. , Sadowsky Michael J. 
Published: July 2002

ABSTRACT

A naturally occurring atrazine-resistant cyanobacterial isolate, strain SG2, was isolated from an atrazine-containing wastewater treatment system at the Syngenta atrazine production facility in St. Gabriel, La. Strain SG2 was resistant to 1,000 μg of atrazine per ml but showed relatively low resistance to diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea]. Analyses of 16S ribosomal DNA indicated that strain SG2 falls into the
Synechocystis
/
Pleurocapsa
/
Microcystis
group. Photosynthetically driven oxygen evolution in strain SG2 was only slightly inhibited (about 10%) by 2,000 μg of atrazine per ml, whereas in the control strain
Synechocystis
6803, oxygen evolution was inhibited 90% by 1,000 μg of atrazine per ml. No atrazine accretion, mineralization, or metabolites were detected when strain SG2 was grown with [
14
C]atrazine. Strain SG2 contained three copies of the
psbA
gene, which encodes the D
1
protein of the photosystem II reaction center. Nucleotide sequence analyses indicated that the
psbA2
and
psbA3
genes encoded predicted proteins with the same amino acid sequence. However, the
psbA1
gene product contained five extra amino acids, which were not found in PsbA proteins from five other cyanobacteria. Moreover, the PsbA1 protein from strain SG2 had an additional 13 amino acid changes compared to the PsbA2/PsbA3 proteins and contained 10 amino acid alterations compared to conserved residues found in other cyanobacteria. Reverse transcriptase PCR analysis indicated that the
psbA1
gene and the
psbA2
/
psbA3
gene(s) were expressed in photosynthetically grown cells in the presence of atrazine. These results suggest that strong selection pressure conferred by the continual input of atrazine has contributed to the evolution of a herbicide-resistant, yet photosynthetically efficient,
psbA
gene in a cyanobacterium.
Spatial Distribution of Total, Ammonia-Oxidizing, and Denitrifying Bacteria in Biological Wastewater Treatment Reactors for Bioregenerative Life Support
Authors: Sakano Yuko , Pickering Karen D. , Strom Peter F. , Kerkhof Lee J. 
Published: July 2002

ABSTRACT

Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project—Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (
amoA
) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (
nosZ
) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of
Proteobacteria
, low-G+C gram-positive bacteria, and a
Cytophaga-Flexibacter-Bacteroides
group. Fifty-seven novel 16S rRNA genes, 8 novel
amoA
genes, and 12 new
nosZ
genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation.
Anti-Idiotypic Antibodies in Patients with Different Clinical Forms of Paracoccidioidomycosis
Authors: Souza A. R. , Gesztesi J.-L. , del Negro G. M. B. , Benard G. , Sato J. , Santos M. V. B. , Abrahão T. B. , Lopes J. D. 
Published: July 2002

ABSTRACTParacoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin America. Patients with PCM show a wide spectrum of clinical and pathological manifestations depending on both host and pathogen factors. Two clinical forms of the disease are recognized: the acute or juvenile form and the chronic or adult form. The major antigenic component of the parasite is a glycoprotein of 43 kDa (gp43). All patient sera present antibodies against gp43 (anti-gp43) and, as demonstrated before by our group, spontaneous anti-idiotypic (anti-Id) antibodies (Ab2) can be detected in patient sera with high titers of anti-gp43. Since it has been postulated that anti-Id antibodies may have a modulating function, we decided to purify and characterize anti-Id antibodies in this system. The possible correlation of Ab2 titers with different clinical forms of disease was also verified. Results showed that purified human anti-Id antibodies (human Ab2) recognized specifically the idiotype of some murine monoclonal anti-gp43 (17c and 3e) but not others (40.d7, 27a, and 8a). Spontaneous anti-Id antibodies were found in all clinical forms of disease. The majority of patients (88%,n= 8) with the acute form of PCM had high titers of Ab2. However, among patients with the multifocal chronic form of the disease, only 29% (n= 14) had high titers of Ab2; 70% (n= 10) of patients with the unifocal chronic form had low titers of Ab2. A correlation between Ab2 titers and anti-gp43 titers was observed before and during antimycotic treatment. Our results suggest that titers of anti-Id antibodies correlate with the severity of PCM in humans.
Serodiagnostic Potential of Culture Filtrate Antigens of
Mycobacterium tuberculosis
Authors: Samanich K. M. , Keen M. A. , Vissa V. D. , Harder J. D. , Spencer J. S. , Belisle J. T. , Zolla-Pazner S. , Laal S. 
Published: July 2002

ABSTRACT

Our studies of the humoral responses of tuberculosis (TB) patients have defined the repertoire of culture filtrate antigens of
Mycobacterium tuberculosis
that are recognized by antibodies from cavitary and noncavitary TB patients and demonstrated that the profile of antigens recognized changes with disease progression (K. Samanich et al., J. Infect. Dis. 178:1534–1538, 1998). We have identified several antigens with strong serodiagnostic potential. In the present study we have evaluated the reactivity of cohorts of human immunodeficiency virus (HIV)-negative, smear-positive; HIV-negative, smear-negative; and HIV-infected TB patients, with three of the candidate antigens, an 88-kDa protein, antigen (Ag) 85C, and MPT32, and compared the reactivity of the same patient cohort with the 38-kDa antigen and Ag 85A. We have also compared the reactivity of native Ag 85C and MPT32 with their recombinant counterparts. The evaluation of the reactivity was done by a modified enzyme-linked immunosorbent assay described earlier (S. Laal et al., Clin. Diag. Lab. Immunol. 4:49–56, 1997), in which all sera are preadsorbed against
Escherichia coli
lysates to reduce the levels of cross-reactive antibodies. Our results demonstrate that (i) antigens identified on the basis of their reactivity with TB patients' sera provide high sensitivities for serodiagnosis, (ii) recombinant Ag 85C and MPT32, expressed in
E. coli
, show reduced reactivity with human TB sera, and (iii) of the panel of antigens tested, the 88-kDa protein is the most promising candidate for serodiagnosis of TB in HIV-infected individuals. Moreover, these results reaffirm that both the extent of the disease and the bacterial load may play a role in determining the antigen profile recognized by antibodies.
Antibody Responses to
Campylobacter
Infections Determined by an Enzyme-Linked Immunosorbent Assay: 2-Year Follow-Up Study of 210 Patients
Authors: Strid Mette Aagaard , Engberg Jørgen , Larsen Lena Brandt , Begtrup Kamilla , Mølbak Kåre , Krogfelt Karen Angeliki 
Published: July 2002

ABSTRACT

An enzyme-linked immunosorbent assay (ELISA) was adapted to measure immunoglobulin G (IgG), IgM, and IgA classes of human serum antibody to
Campylobacter jejuni
and
Campylobacter coli
. Heat-stable antigen, a combination of
C. jejuni
serotype O:1,44 and O:53 in the ratio 1:1, was used as a coating antigen in the ELISA test. A total of 631 sera from 210 patients with verified
Campylobacter
enteritis were examined at various intervals after infection, and a control group of 164 sera were tested to determine the cut-off for negative results. With a 90th percentile of specificity, IgG, IgM, and IgA showed a sensitivity of 71, 60, and 80%, respectively. By combining all three antibody classes, the sensitivity was 92% within 35 days after infection, whereas within 90 days after infection, a combined sensitivity of 90% was found (IgG 68%, IgM 52%, and IgA 76%). At follow-up of the patients, IgG antibodies were elevated 4.5 months after infection but exhibited a large degree of variation in antibody decay profiles. IgA and IgM antibodies were elevated during the acute phase of infection (up to 2 months from onset of infection). The antibody response did not depend on
Campylobacter
species or
C. jejuni
serotype, with the important exception of response to
C. jejuni
O:19, the serotype most frequently associated with Guillain-Barré syndrome. All of the patients infected with this serotype had higher levels of both IgM (
P
= 0.006) and IgA (
P
= 0.06) compared with other
C. jejuni
and
C. coli
serotypes.
Self Antigen Prognostic for Human Immunodeficiency Virus Disease Progression
Authors: Bristow Cynthia L. , Patel Hirenkumar , Arnold Roland R. 
Published: July 2002

ABSTRACTWe have recently found that an extracellular protein, α1proteinase inhibitor (α1PI; α1antitrypsin), is required for in vitro human immunodeficiency virus (HIV) infectivity outcome. We show here in a study of HIV-seropositive patients that decreased viral load is significantly correlated with decreased circulating α1PI. In the asymptomatic category of HIV disease, 100% of patients manifest deficient levels of active α1PI, a condition known to lead to degenerative lung diseases and a dramatically reduced life span. Further, HIV-associated α1PI deficiency is correlated with circulating anti-α1PI immunoglobulin G. These results suggest that preventing HIV-associated α1PI deficiency may provide a strategic target for preventing HIV-associated pathophysiology.
Identification and Characterization of Murine Cytotoxic T Cells That KillMycobacterium tuberculosis
Authors: Silva Celio L. , Lowrie Douglas B. 
Published: July 2002

ABSTRACTAs we seek to develop and evaluate new vaccines against tuberculosis, it is desirable that we understand the mechanisms of protective immunity in our models. Adoptive transfer of protection with hsp65-specific T-cell clones from infected or vaccinated mice into naı̈ve mice had indicated that cytotoxic T cells can make a major contribution to protection. We characterized 28 CD4+CD8−and 28 CD4−CD8+hsp65-specific T-cell clones derived from infected or vaccinated mice. Half of the CD4+CD8−and 64% of the CD4−CD8+clones were cytotoxic. Cytotoxicity was associated with high expression of CD44 and gamma interferon production. Most (86%) of the cytotoxic CD4+CD8−clones lysed target cells via the Fas-FasL pathway, and most (83%) of the cytotoxic CD4−CD8+clones lysed target cells via cytotoxic granules. Only the clones using the granule-mediated pathway caused substantial loss of viability of virulentMycobacterium tuberculosisduring lysis of infected macrophages, and the degree of killing closely correlated with the availability of granule marker enzyme activity. Granule-mediated cytotoxicity thus may have a key role in protection against tuberculosis by delivering mycobactericidal granule contents.
Guillain-Barré Syndrome- and Miller Fisher Syndrome-Associated
Campylobacter jejuni
Lipopolysaccharides Induce Anti-GM
1
and Anti-GQ
1b
Antibodies in Rabbits
Authors: Ang C. W. , De Klerk M. A. , Endtz H. P. , Jacobs B. C. , Laman J. D. , van der Meché F. G. A. , van Doorn P. A. 
Published: July 2002

ABSTRACT

Campylobacter jejuni
infections are thought to induce antiganglioside antibodies in patients with Guillain-Barrésyndrome (GBS) and Miller Fisher syndrome (MFS) by molecular mimicry between
C. jejuni
lipopolysaccharides (LPS) and gangliosides. We used purified LPS fractions from five
Campylobacter
strains to induce antiganglioside responses in rabbits. The animals that received injections with LPS from GBS-associated strains developed anti-GM
1
and anti-GA
1
antibodies. Animals injected with LPS from one MFS-related
C. jejuni
strain produced anti-GQ
1b
antibodies. Rabbits that were injected with Penner O:3 LPS had a strong anti-LPS response, but no antiganglioside reactivity was observed. The antiganglioside specificity in the rabbits reflected the specificity in the patients from whom the strains were isolated. In conclusion, our results indicate that an immune response against GBS- and MFS-associated
C. jejuni
LPS results in antiganglioside antibodies. These results provide strong support for molecular mimicry as a mechanism in the induction of antiganglioside antibodies following infections.
Assessing Vascular Permeability during Experimental Cerebral Malaria by a Radiolabeled Monoclonal Antibody Technique
Authors: van der Heyde Henri C. , Bauer Philippe , Sun Guang , Chang Wun-Ling , Yin Lijia , Fuseler John , Granger D. Neil 
Published: July 2002

ABSTRACTVascular endothelial integrity, assessed by Evans blue dye extrusion and radiolabeled monoclonal antibody leakage, was markedly compromised in the brain, lung, kidney, and heart duringPlasmodium bergheiinfection, a well-recognized model for human cerebral malaria. The results for vascular permeability from both methods were significantly (P< 0.001) related.
Polymorphisms in Pilin Glycosylation Locus of
Neisseria meningitidis
Expressing Class II Pili
Authors: Kahler Charlene M. , Martin Larry E. , Tzeng Yih-Ling , Miller Yoon K. , Sharkey Kerith , Stephens David S. , Davies John K. 
Published: July 2002

ABSTRACT

We have located a locus,
pgl
, in
Neisseria meningitidis
strain NMB required for the glycosylation of class II pili. Between five and eight open reading frames (ORFs) (
pglF, pglB, pglC, pglB2, orf2, orf3, orf8
, and
avtA
) were present in the
pgl
clusters of different meningococcal isolates. The Class I pilus-expressing strains
Neisseria gonorrhoeae
MS11 and
N. meningitidis
MC58 each contain a
pgl
cluster in which
orf2
and
orf3
have been deleted. Strain NMB and other meningococcal isolates which express class II type IV pili contained
pgl
clusters in which
pglB
had been replaced by
pglB2
and an additional novel ORF,
orf8
, had been inserted between
pglB2
and
pglC
. Insertional inactivation of the eight ORFs of the
pgl
cluster of strain NMB showed that
pglF, pglB2, pglC
, and
pglD,
but not
orf2, orf3, orf8
, and
avtA
, were necessary for pilin glycosylation. Pilin glycosylation was not essential for resistance to normal human serum, as
pglF
and
pglD
mutants retained wild-type levels of serum resistance. Although
pglB2
and
pglC
mutants were significantly sensitive to normal human serum under the experimental conditions used, subsequent examination of the encapsulation phenotypes revealed that
pglB2
and
pglC
mutants expressed almost 50% less capsule than wild-type NMB. A mutation in
orf3
, which did not affect pilin glycosylation, also resulted in a 10% reduction in capsule expression and a moderately serum sensitive phenotype. On the basis of these results we suggest that pilin glycosylation may proceed via a lipid-linked oligosaccharide intermediate and that blockages in this pathway may interfere with capsular transport or assembly.
Variance in Fibronectin Binding and
fnb
Locus Polymorphisms in
Staphylococcus aureus
: Identification of Antigenic Variation in a Fibronectin Binding Protein Adhesin of the Epidemic CMRSA-1 Strain of Methicillin-Resistant
S. aureus
Authors: Rice Kelly , Huesca Mario , Vaz Dareyl , McGavin Martin J. 
Published: July 2002

ABSTRACT

The
fnbA
and
fnbB
genes of
Staphylococcus aureus
8325-4 encode fibronectin (Fn) binding proteins FnBPA and FnBPB, which promote adherence to host tissues. Each adhesin contains three copies of a repeated D motif that binds Fn and is a target for vaccine development. In this study, we assess variability within the Fn-binding domain of the FnBP adhesins and evaluate factors that promote variance in Fn binding among clinical isolates. Based on variation in the number of
fnb
genes or the number of D motifs, we identified five polymorphism groups.
S. aureus
8325-4 and 91% of methicillin-resistant
S. aureus
(MRSA) isolates belong to polymorphism group I, with two
fnb
genes and three copies of the D motif. Polymorphism group II contained one
fnb
gene with only two D motifs and was associated with the epidemic CMRSA-4 strain, which exhibited high protease activity and low Fn binding. Polymorphism group III was unique to the epidemic CMRSA-1 strain, defined by the presence of a fourth D motif that exhibited antigenic variation within a conserved sequence that is essential for Fn binding. However, the sequence of the D motifs was otherwise highly conserved among the other polymorphism groups. Variation in Fn binding among MRSA isolates was inversely related to protease activity but not to the number of
fnb
genes or the number of D motifs. Therefore, the
fnb
locus is polymorphic in a small number of strains, but this does not contribute to variation in Fn binding. The antigenic variation that was observed only in the epidemic CMRSA-1 strain may have evolved in response to a host immune response encountered during successive cycles of colonization, transmission, and infection in the nosocomial environment.
Effect of Purified Lipopolysaccharides from Strains of
Helicobacter pylori
and
Helicobacter felis
on Acid Secretion in Mouse Gastric Glands In Vitro
Authors: Padol Ireneusz T. , Moran Anthony P. , Hunt Richard H. 
Published: July 2002

ABSTRACT

As a bacterial product,
Helicobacter pylori
lipopolysaccharide (LPS) can originate in close proximity to parietal cells, but the role of this uniquely structured endotoxin on acid secretion has not been fully investigated and remains unclear. The purpose of this study was to test the direct effect of purified LPS (tested range, 0.1 to 100 μg/ml) from various strains of
H. pylori
and from one
Helicobacter felis
strain on histamine- and carbachol-stimulated acid secretion in vitro using mouse gastric glands and the accumulation of [
14
C]aminopyrine. In addition, we investigated whether
H. pylori
LPS can interfere with two native antisecretory substances, prostaglandin E
2
(PGE
2
) and somatostatin, which may contribute to bacterial pathogenicity. Except for the LPS from
H. pylori
SS1 (Sydney strain), which gave a statistically significant increase in both histamine- and carbachol-stimulated acid output (38 and 24%, respectively;
P
< 0.05), no effect of the tested LPS was observed on acid secretion.
H. pylori
LPS purified from a patient isolate did not affect the potency or the efficacy of the inhibitory dose response curve to PGE
2
or somatostatin. Bacterial interstrain variation in the direct stimulatory effect of
Helicobacter
-derived LPS on acid secretion was observed, which probably reflects the molecular structure of LPS and the potential to contribute to virulence. Importantly, the data showed that
H. pylori
LPS did not have any direct antisecretory properties. It can be speculated that the acid stimulatory properties of LPS from
H. pylori
SS1 may contribute to the gastric damage observed in the mouse model of
H. pylori
infection.
γ-Glutamyltransferase Is a
Helicobacter pylori
Virulence Factor but Is Not Essential for Colonization
Authors: McGovern K. J. , Blanchard T. G. , Gutierrez J. A. , Czinn S. J. , Krakowka S. , Youngman P. 
Published: July 2002

ABSTRACT

The contribution of glutamyl transpeptidase (GGT) (γ-glutamyltransferase [EC 2. 3. 2. 2]) to
Helicobacter pylori
virulence was investigated in piglets and mice using GGT-deficient isogenic strains. All animals became colonized. However, the bacterial load was significantly lower for mutant bacteria than for parent strains. These results suggest that GGT activity provides an advantage to
H. pylori
in colonization.
Virulence Gene Identification by Differential Fluorescence Induction Analysis of
Staphylococcus aureus
Gene Expression during Infection-Simulating Culture
Authors: Schneider William P. , Ho Sun K. , Christine Jillian , Yao Monique , Marra Andrea , Hromockyj Alexander E. 
Published: July 2002

ABSTRACT

We have employed a strategy utilizing differential fluorescence induction (DFI) in an effort to identify
Staphylococcus aureus
genes whose products can be targeted for antimicrobial drug development. DFI allows identification of promoters preferentially active under given growth conditions on the basis of their ability to drive expression of a promoterless green fluorescent protein gene (
gfp
). A plasmid-based promoter trap library was constructed of 200- to 1,000-bp fragments of
S. aureus
genomic DNA fused to
gfp
, and clones with active promoters were isolated under seven different in vitro growth conditions simulating infection. Six thousand two hundred sixty-seven clones with active promoters were screened to identify those that exhibited differential promoter activity. Bioinformatic analysis allowed the identification of 42 unique operons, containing a total of 61 genes, immediately downstream of the differentially active putative promoters. Replacement mutations were generated for most of these operons, and the abilities of the resulting mutants to cause infection were assessed in two different murine infection models. Approximately 40% of the mutants were attenuated in at least one infection model.