bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microarray Analysis of Quorum-Sensing-Regulated Genes inPorphyromonas gingivalis
Authors: Yuan Lihui , Hillman Jeffrey D. , Progulske-Fox Ann 
Published: June 2005

ABSTRACTQuorum sensing is a phenomenon defined as gene regulation in response to cell density that regulates various functions in bacteria. The periodontopathogenPorphyromonas gingivalispossesses aluxSgene homologue that may encode a quorum-sensing system. In order to identify genes ofP. gingivalisthat are regulated byluxS, gene expression analysis was done using microarrays and RNA samples from the W83 wild-type strain and an isogenicluxSmutant, LY2001. The results indicated that 17 open reading frames (ORFs) in LY2001 are upregulated and two are downregulated. Real-time PCR was done to confirm the microarray results. Among the upregulated ORFs is a group of stress-related genes, includinghtrA,clpB,groEL,dnaK, and the F subunit of alkyl hydroperoxide reductase. This suggested thatluxSis involved in stress gene regulation inP. gingivalis. Stress response experiments, including high-temperature survival, resistance to hydrogen peroxide (H2O2), and survival during exposure to low and high pH, were performed on theP. gingivaliswild-type and LY2001 strains. LY2001 had a significantly higher survival rate than did W83 when stressed at 50°C. No difference was found at pH 5, but LY2001 had increased survival compared to W83 at pH 9. LY2001 also survived better than W83 when stressed with 0.35 mM H2O2. These results suggest thatluxSmight be involved in promoting survival ofP. gingivalisin the host by regulating its response to host-induced stresses such as temperature, H2O2, and pH.
Superoxide Production in
Galleria mellonella
Hemocytes: Identification of Proteins Homologous to the NADPH Oxidase Complex of Human Neutrophils
Authors: Bergin David , Reeves Emer P. , Renwick Julie , Wientjes Frans B. , Kavanagh Kevin 
Published: June 2005

ABSTRACT

The insect immune response has a number of structural and functional similarities to the innate immune response of mammals. The objective of the work presented here was to establish the mechanism by which insect hemocytes produce superoxide and to ascertain whether the proteins involved in superoxide production are similar to those involved in the NADPH oxidase-induced superoxide production in human neutrophils. Hemocytes of the greater wax moth (
Galleria mellonella
) were shown to be capable of phagocytosing bacterial and fungal cells. The kinetics of phagocytosis and microbial killing were similar in the insect hemocytes and human neutrophils. Superoxide production and microbial killing by both cell types were inhibited in the presence of the NADPH oxidase inhibitor diphenyleneiodonium chloride. Immunoblotting of
G. mellonella
hemocytes with antibodies raised against human neutrophil
phox
proteins revealed the presence of proteins homologous to gp91
phox
, p67
phox
, p47
phox
, and the GTP-binding protein rac 2. A protein equivalent to p40
phox
was not detected in insect hemocytes. Immunofluorescence analysis localized insect 47-kDa and 67-kDa proteins throughout the cytosol and in the perinuclear region. Hemocyte 67-kDa and 47-kDa proteins were immunoprecipitated and analyzed by matrix-assisted laser desorption ionization—time of flight analysis. The results revealed that the hemocyte 67-kDa and 47-kDa proteins contained peptides matching those of p67
phox
and p47
phox
of human neutrophils. The results presented here indicate that insect hemocytes phagocytose and kill bacterial and fungal cells by a mechanism similar to the mechanism used by human neutrophils via the production of superoxide. We identified proteins homologous to a number of proteins essential for superoxide production in human neutrophils and demonstrated that significant regions of the 67-kDa and 47-kDa insect proteins are identical to regions of the p67
phox
and p47
phox
proteins of neutrophils.
Neisseria gonorrhoeaeKills Carcinoembryonic Antigen-Related Cellular Adhesion Molecule 1 (CD66a)-Expressing Human B Cells and Inhibits Antibody Production
Authors: Pantelic Milica , Kim Young-June , Bolland Silvia , Chen Ines , Shively John , Chen Tie 
Published: June 2005

ABSTRACTNeisseria gonorrhoeaecells (gonococci [GC]), the etiological agents for gonorrhea, can cause repeated infections. During and after gonococcal infection, local and systemic antigonococcal antibody levels are low. These clinical data indicate the possibility that GC may suppress immune responses during infection. Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1 or CD66a), a receptor for GC opacity (Opa) proteins, was shown to mediate inhibitory signals. In the present study, human B cells were activated by interleukin-2 to express CEACAM1 and then stimulated to secrete antibodies and simultaneously coincubated with Opa−and OpaI GC of strain MS11. Our results show that this OpaI GC has the ability to inhibit antibody production. The interaction of GC and CEACAM1 with human peripheral B cells also results in induction of cell death. The same findings were observed in DT40 B cells. This CEACAM1-promoted cell death pathway does not involve the inhibitory signals or the tyrosine phosphatases SHP-1 and SHP-2 but depends on Bruton's tyrosine kinase in DT40 cells. Our results suggest thatNeisseria gonorrhoeaepossesses the ability to suppress antibody production by killing CEACAM1-expressing B cells.
The Gonococcal Fur-Regulated
tbpA
and
tbpB
Genes Are Expressed during Natural Mucosal Gonococcal Infection
Authors: Agarwal Sarika , King Carol A. , Klein Ellen K. , Soper David E. , Rice Peter A. , Wetzler Lee M. , Genco Caroline A. 
Published: June 2005

ABSTRACT

Iron is limiting in the human host, and bacterial pathogens respond to this environment by regulating gene expression through the ferric uptake regulator protein (Fur). In vitro studies have demonstrated that
Neisseria gonorrhoeae
controls the expression of several critical genes through an iron- and Fur-mediated mechanism. While most in vitro experiments are designed to determine the response of
N. gonorrhoeae
to an exogenous iron concentration of zero, these organisms are unlikely to be exposed to such severe limitations of iron in vivo. To determine if
N. gonorrhoeae
expresses iron- and Fur-regulated genes in vivo during uncomplicated gonococcal infection, we examined gene expression profiles of specimens obtained from male subjects with urethral infections. RNA was isolated from urethral swab specimens and used as a template to amplify, by reverse transcriptase PCR (RT-PCR), gonococcal genes known to be regulated by iron and Fur (
tbpA
,
tbpB
, and
fur
). The constitutively expressed gonococcal
rmp
gene was used as a positive control. RT-PCR analysis indicated that gonorrhea-positive specimens where
rmp
expression was seen were also 93% (51/55)
fbpA
positive, 87% (48/55)
tbpA
positive, and 86% (14 of 16 tested)
tbpB
positive. In addition, we detected a
fur
transcript in 79% (37 of 47 tested) of positive specimens. We also measured increases in levels of immunoglobulin G antibody against TbpA (91%) and TbpB (73%) antigens in sera from infected male subjects compared to those in uninfected controls. A positive trend between
tbpA
gene expression and TbpA antibody levels in sera indicated a relationship between levels of gene expression and immune response in male subjects infected with gonorrhea for the first time. These results indicate that gonococcal iron- and Fur-regulated
tbpA
and
tbpB
genes are expressed in gonococcal infection and that male subjects with mucosal gonococcal infections exhibit antibodies to these proteins.
Inhibition of Chondroitin-4-Sulfate-Specific Adhesion of
Plasmodium falciparum
-Infected Erythrocytes by Sulfated Polysaccharides
Authors: Andrews Katherine T. , Klatt Nicole , Adams Yvonne , Mischnick Petra , Schwartz-Albiez Reinhard 
Published: June 2005

ABSTRACT

Adhesion of
Plasmodium falciparum
-infected erythrocytes to placental chondroitin 4-sulfate (CSA) has been linked to the severe disease outcome of pregnancy-associated malaria. Soluble polysaccharides that release mature-stage parasitized erythrocytes into the peripheral circulation may help elucidate these interactions and have the potential to aid in developing therapeutic strategies. We have screened a panel of 11 sulfated polysaccharides for their capacities to inhibit adhesion of infected erythrocytes to CSA expressed on CHO-K1 cells and ex vivo human placental tissue. Two carrageenans and a cellulose sulfate (CS10) were able to inhibit adhesion to CSA and to cause already bound infected erythrocytes to de-adhere in a dose-dependent manner. CS10, like CSA and in contrast to all other compounds tested, remained bound to infected erythrocytes after washing and continued to inhibit binding. Both carrageenans and CS10 inhibited adhesion to placental tissue. Although highly sulfated dextran sulfate can inhibit CSA-mediated adhesion to CHO cells, this polysaccharide amplified adhesion to placental tissue severalfold, demonstrating the importance of evaluating inhibitory compounds in systems as close to in vivo as possible. Interestingly, and in contrast to all other compounds tested, which had a random distribution of sulfate groups, CS10 exhibited a clustered sulfate pattern along the polymer chain, similar to that of the undersulfated placental CSA preferred by placental-tissue-binding infected erythrocytes. Therefore, the specific antiadhesive capacity observed here seems to depend not only on the degree of charge and sulfation but also on a particular pattern of sulfation.
Effects of a Probiotic Strain ofEnterococcus faeciumon the Rate of Natural Chlamydia Infection in Swine
Authors: Pollmann M. , Nordhoff M. , Pospischil A. , Tedin K. , Wieler L. H. 
Published: June 2005

ABSTRACTChlamydiae are obligately intracellular pathogens which cause infections associated with a broad range of diseases in both livestock and humans. In addition, a large proportion of animals may become persistently infected asymptomatic carriers and serve as reservoirs for other animals which also shed these potential zoonotic pathogens. Reducing the chlamydial load of animals is therefore of major importance, and since large-scale antibiotic treatment is neither desired nor feasible, alternative means of prevention are needed. Here we performed a study comparing the efficacy of a probiotic strain ofEnterococcus faeciumon the reduction of both the rate of natural infection and the shedding of chlamydiae in swine. The presence ofChlamydiaceaewas detected by species-specific PCR of fecal samples of sows taken at three times prior to the birth of piglets. Piglets delivered from chlamydia-positive sows in either the control or the probiotic group were also examined for the frequency of chlamydiae at various ages. Eighty-five percent of the piglets from the control group were found to be chlamydia positive, whereas chlamydiae were found in only 60% of piglets from the probiotic group, results confirmed by fluorescence in situ hybridization and immunohistology, which showed higher rates of infection in the control group. In addition to the reduced frequency of chlamydia-positive piglets in the probiotic group, the time of appearance of positive samples was delayed. To our knowledge, these data show for the first time that a probiotic strain ofE. faeciumcan reduce the rate of carryover infections of piglets by obligate intracellular pathogens.
SlyA Regulates Function of
Salmonella
Pathogenicity Island 2 (SPI-2) and Expression of SPI-2-Associated Genes
Authors: Linehan Sheena A. , Rytkönen Anne , Yu Xiu-Jun , Liu Mei , Holden David W. 
Published: June 2005

ABSTRACT

During the systemic phase of murine infection with
Salmonella enterica
serovar Typhimurium, bacterial virulence is correlated with the ability to grow and survive within host macrophages.
Salmonella
pathogenicity island 2 (SPI-2), encoding a type three secretion system, has emerged as an important contributor to
Salmonella
intracellular growth. SPI-2 mutants have been proposed to be more accessible than wild-type
Salmonella
to oxyradicals generated by the NADPH phagocyte oxidase. We performed mixed infections of mice to investigate the relationship between SPI-2 and SlyA, a transcriptional regulator that confers resistance to oxyradicals. In mixed-infection experiments, the SPI-2 null mutant was severely attenuated in virulence, whereas
slyA
mutants were only mildly attenuated. Surprisingly, further experiments indicated that the function of SPI-2 was partially dependent on
slyA
. The intracellular behavior of a
slyA
mutant in infected cells was consistent with inefficient SPI-2 expression, as formation of
Salmonella
-induced filaments and the intracellular F-actin meshwork, features that depend on SPI-2, were present at abnormally low frequencies. Furthermore, the translocated levels of the SPI-2 effector SseJ were severely reduced in a strain carrying a mutation in
slyA
. We used flow cytometry to investigate the role of SlyA in expression of green fluorescent protein (GFP) from transcriptional fusions with promoters of either of two other SPI-2 effector genes,
sifB
and
sifA
. The
slyA
mutant exhibited reduced GFP expression from both promoters. Combining mutations in
slyA
and other regulators of SPI-2 indicated that SlyA acts through the SsrAB two-component regulatory system. SlyA exhibits partial functional redundancy with OmpR-EnvZ and contributes to the transcriptional response to low osmolarity and the absence of calcium, two environmental stimuli that promote SPI-2 gene expression.
LidA, a Translocated Substrate of the
Legionella pneumophila
Type IV Secretion System, Interferes with the Early Secretory Pathway
Authors: Derré Isabelle , Isberg Ralph R. 
Published: June 2005

ABSTRACT

Legionella pneumophila
uses a type IV secretion system to deliver effector molecules into the host cell and establish its replication vacuole. In this study, we investigated the role of LidA, a translocated substrate associated with the surface of the
L. pneumophila
-containing vacuole. LidA is secreted into the host cell throughout the replication cycle of the bacteria and associates with compartments of the early secretory pathway. When overexpressed in mammalian cells or yeast, LidA interferes with the early secretory pathway, probably via a domain predicted to be rich in coiled-coil structure. Finally, during intracellular replication, the replication vacuoles are in close contact with the endoplasmic reticulum-Golgi intermediate compartment and the Golgi apparatus, suggesting a positive correlation between intracellular growth and association of the vacuole with compartments of the early secretory pathway. We propose that LidA is involved in the recruitment of early secretory vesicles to the
L. pneumophila
-containing vacuole and that the vacuole associates with the secretory pathway to facilitate this process.
Role of the Distal
sarA
Promoters in SarA Expression in
Staphylococcus aureus
Authors: Cheung Ambrose L. , Manna Adhar C. 
Published: June 2005

ABSTRACT

The global regulatory locus
sarA
comprises a 375-bp open reading frame that is driven by three promoters, the proximal P1 and distal P3 and P2 promoters. We mutated the weaker P3 and P2 promoters to ascertain the effect of the change on SarA protein and target gene expression. Our results indicated that the solely active P1 promoter led to a lower SarA protein level, which has an effect on
agr
transcription and subsequently had corresponding effects on
hla
,
sspA
, and
spa
transcription, probably in both
agr
-independent and
agr
-dependent manners.
Role of Motility and Flagellin Glycosylation in the Pathogenesis of
Pseudomonas aeruginosa
Burn Wound Infections
Authors: Arora Shiwani K. , Neely Alice N. , Blair Barbara , Lory Stephen , Ramphal Reuben 
Published: June 2005

ABSTRACT

In this study, we tested the contribution of flagellar motility, flagellin structure, and its glycosylation in
Pseudomonas aeruginosa
using genetically defined flagellar mutants. All mutants and their parent strains were tested in a burned-mouse model of infection. Motility and glycosylation of the flagellum appear to be important determinants of flagellar-mediated virulence in this model. This is the first report where genetically defined flagellar variants of
P. aeruginosa
were tested in the burned-mouse model of infection.
Structural Diversity of Streptokinase and Activation of Human Plasminogen
Authors: Lizano Sergio , Johnston Kenneth H. 
Published: June 2005

ABSTRACT
The β domain of streptokinase is required for plasminogen activation and contains a region of sequence diversity associated with infection and disease in group A streptococci. We report that mutagenesis of this polymorphic region does not alter plasminogen activation, which suggests an alternative function for this molecular motif in streptococcal disease.
Certain Site-Directed, Nonenzymatically Active Mutants of the
Haemophilus influenzae
P4 Lipoprotein Are Able To Elicit Bactericidal Antibodies
Authors: Green Bruce A. , Baranyi Elizabeth , Reilly Thomas J. , Smith Arnold L. , Zlotnick Gary W. 
Published: June 2005

ABSTRACT

The
Haemophilus influenzae
P4 lipoprotein (
hel
) is a potential component of a nontypeable
H. influenzae
otitis media vaccine. Since P4 is known to be an enzyme, nonenzymatically active forms of recombinant P4 are required. After site-directed mutagenesis of the
hel
gene, three of the mutated proteins were shown to be vaccine candidates.
Warm Season Rainfall Variability over the U.S. Great Plains in Observations, NCEP and ERA-40 Reanalyses, and NCAR and NASA Atmospheric Model Simulations
Authors: Ruiz-Barradas Alfredo , Nigam Sumant 
Published: June 2005

Abstract
Interannual variability of Great Plains precipitation in the warm season months is analyzed using gridded observations, satellite-based precipitation estimates, NCEP reanalysis data and the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data, and the half-century-long NCAR Community Atmosphere Model (CAM3.0, version 3.0) and the National Aeronautics and Space Administration (NASA) Seasonal-to-Intraseasonal Prediction Project (NSIPP) atmospheric model simulations. Regional hydroclimate is the focus because of its immense societal impact and because the involved variability mechanisms are not well understood.
The Great Plains precipitation variability is represented rather differently, and only quasi realistically, in the reanalyses. NCEP has larger amplitude but less traction with observations in comparison with ERA-40. Model simulations exhibit more realistic amplitudes, which are between those of NCEP and ERA-40. The simulated variability is however uncorrelated with observations in both models, with monthly correlations smaller than 0.10 in all cases. An assessment of the regional atmosphere water balance is revealing: Stationary moisture flux convergence accounts for most of the Great Plains variability in ERA-40, but not in the NCEP reanalysis and model simulations; convergent fluxes generate less than half of the precipitation in the latter, while local evaporation does the rest in models.
Phenomenal evaporation in the models—up to 4 times larger than the highest observationally constrained estimate (NCEP’s)—provides the bulk of the moisture for Great Plains precipitation variability; thus, precipitation recycling is very efficient in both models, perhaps too efficient.
Remote water sources contribute substantially to Great Plains hydroclimate variability in nature via fluxes. Getting the interaction pathways right is presently challenging for the models.
Dominant Modes of Variability in the South Atlantic: A Study with a Hierarchy of Ocean–Atmosphere Models
Authors: Haarsma Reindert J. , Campos Edmo J. D. , Hazeleger Wilco , Severijns Camiel , Piola Alberto R. , Molteni Franco 
Published: June 2005

Abstract
Using an atmosphere model of intermediate complexity and a hierarchy of ocean models, the dominant modes of interannual and decadal variability in the South Atlantic Ocean are studied. The atmosphere Simplified Parameterizations Primitive Equation Dynamics (SPEEDY) model has T30L7 resolution. The physical package consists of a set of simplified physical parameterization schemes, based on the same principles adopted in the schemes of state-of-the-art AGCMs. It is at least an order of magnitude faster, whereas the quality of the simulated climate compares well with those models. The hierarchy of ocean models consists of simple mixed layer models with an increasing number of physical processes involved such as Ekman transport, wind-induced mixing, and wind-driven barotropic transport. Finally, the atmosphere model is coupled to a regional version of the Miami Isopycnal Coordinate Ocean Model (MICOM) covering the South Atlantic with a horizontal resolution of 1° and 16 vertical layers.
The coupled modes of mean sea level pressure and sea surface temperature simulated by SPEEDY–MICOM strongly resemble the modes as analyzed from the NCEP–NCAR reanalysis, indicating that this model configuration possesses the required physical mechanisms for generating these modes of variability. Using the ocean model hierarchy the authors were able to show that turbulent heat fluxes, Ekman transport, and wind-induced mixing contribute to the generation of the dominant modes of coupled SST variability. The different roles of these terms in generating these modes are analyzed. Variations in the wind-driven barotropic transport mainly seem to affect the SST variability in the Brazil–Malvinas confluence zone.
The spectra of the mixed layer models appeared to be too red in comparison with the fully coupled SPEEDY–MICOM model due to the too strong coupling between SST and surface air temperatures (SATs), resulting from the inability to advect and subduct SST anomalies by the mixed layer models. In SPEEDY–MICOM anomalies in the southeastern corner of the South Atlantic are subducted and advected toward the north Brazilian coast on a time scale of about 6 yr.
Statistical–Dynamical Seasonal Forecasts of Central-Southwest Asian Winter Precipitation
Authors: Tippett Michael K. , Goddard Lisa , Barnston Anthony G. 
Published: June 2005

Abstract
Interannual precipitation variability in central-southwest (CSW) Asia has been associated with East Asian jet stream variability and western Pacific tropical convection. However, atmospheric general circulation models (AGCMs) forced by observed sea surface temperature (SST) poorly simulate the region’s interannual precipitation variability. The statistical–dynamical approach uses statistical methods to correct systematic deficiencies in the response of AGCMs to SST forcing. Statistical correction methods linking model-simulated Indo–west Pacific precipitation and observed CSW Asia precipitation result in modest, but statistically significant, cross-validated simulation skill in the northeast part of the domain for the period from 1951 to 1998. The statistical–dynamical method is also applied to recent (winter 1998/99 to 2002/03) multimodel, two-tier December–March precipitation forecasts initiated in October. This period includes 4 yr (winter of 1998/99 to 2001/02) of severe drought. Tercile probability forecasts are produced using ensemble-mean forecasts and forecast error estimates. The statistical–dynamical forecasts show enhanced probability of below-normal precipitation for the four drought years and capture the return to normal conditions in part of the region during the winter of 2002/03.
May Kabul be without gold, but not without snow.
—Traditional Afghan proverb