bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epidemiologic, Experimental, and Clinical Links between Respiratory Syncytial Virus Infection and Asthma
Authors: Mohapatra Shyam S. , Boyapalle Sandhya 
Published: July 2008

SUMMARYVirtually all children experience respiratory syncytial virus (RSV) infection at least once during the first 2 years of life, but only a few develop bronchiolitis and more severe disease requiring hospitalization, usually in the first 6 months of life. Children who recover from RSV-induced bronchiolitis are at increased risk for the development of recurrent wheeze and asthma in later childhood. Recent studies suggest that there is an association between RSV-induced bronchiolitis and asthma within the first decade of life but that this association is not significant after age 13. Despite the considerable progress made in our understanding of several aspects of respiratory viral infections, further work needs to be done to clarify the molecular mechanisms of early interactions between virus and host cell and the role of host gene products in the infection process. This review provides a critical appraisal of the literature in epidemiology and experimental research which links RSV infection to asthma. Studies to date demonstrate that there is a significant association between RSV infection and childhood asthma and that preventing severe primary RSV infections can decrease the risk of childhood asthma.
Host-Pathogen Interactions inCampylobacterInfections: the Host Perspective
Authors: Janssen Riny , Krogfelt Karen A. , Cawthraw Shaun A. , van Pelt Wilfrid , Wagenaar Jaap A. , Owen Robert J. 
Published: July 2008

SUMMARYCampylobacteris a major cause of acute bacterial diarrhea in humans worldwide. This study was aimed at summarizing the current understanding of host mechanisms involved in the defense againstCampylobacterby evaluating data available from three sources: (i) epidemiological observations, (ii) observations of patients, and (iii) experimental observations including observations of animal models and human volunteer studies. Analysis of available data clearly indicates that an effective immune system is crucial for the host defense againstCampylobacterinfection. Innate, cell-mediated, and humoral immune responses are induced duringCampylobacterinfection, but the relative importance of these mechanisms in conferring protective immunity against reinfection is unclear. Frequent exposure toCampylobacterdoes lead to the induction of short-term protection against disease but most probably not against colonization. Recent progress in the development of more suitable animal models for studyingCampylobacterinfection has opened up possibilities to study the importance of innate and adaptive immunity during infection and in protection against reinfection. In addition, advances in genomics and proteomics technologies will enable more detailed molecular studies. Such studies combined with better integration of host and pathogen research driven by epidemiological findings may truly advance our understanding ofCampylobacterinfection in humans.
Malaria Chemoprophylaxis: Strategies for Risk Groups
Authors: Schlagenhauf Patricia , Petersen Eskild 
Published: July 2008

SUMMARY

The risk of malaria for travelers varies from region to region and depends on the intensity of transmission, the duration of the stay in the area of endemicity, the style of travel, and the efficacy of preventive measures. The decision to recommend chemoprophylaxis to travelers to areas with a low risk of malarial infection is especially difficult because the risk of infection must be balanced with the risk of experiencing side effects. If the risk of side effects by far exceeds the risk of infection, the traveler needs information on measures against mosquito bites and advice on prompt diagnosis and self-treatment. The risk is difficult to quantify, and the absolute risk for travelers to most areas is not known, especially because the populations at risk are unknown. We propose here that the best approximation of the risk to the traveler to a specific area is to use the risk to the indigenous population as a guideline for the risk to the traveler, and we provide examples on how risk in the indigenous population can be used for the estimation of risk of malarial infection for travelers. Special groups are long-term visitors and residents, who often perceive risk differently, cease using chemoprophylaxis, and rely on self-diagnosis and treatment. For long-term visitors, the problem of fake drugs needs to be discussed. Strategies for chemoprophylaxis and self-treatment of pregnant women and small children are discussed. So far, malaria prophylaxis is recommended to prevent
Plasmodium falciparum
infections, and primaquine prophylaxis against persistent
Plasmodium vivax
and
Plasmodium ovale
infections in travelers is not recommended.
Rho5p Is Involved in Mediating the Osmotic Stress Response in
Saccharomyces cerevisiae
, and Its Activity Is Regulated via Msi1p and Npr1p by Phosphorylation and Ubiquitination
Authors: Annan Robert B. , Wu Cunle , Waller Daniel D. , Whiteway Malcolm , Thomas David Y. 
Published: July 2008

ABSTRACT

Small GTPases of the Rho family act as molecular switches, and modulation of the GTP-bound state of Rho proteins is a well-characterized means of regulating their signaling activity in vivo. In contrast, the regulation of Rho-type GTPases by posttranslational modifications is poorly understood. Here, we present evidence of the control of the
Saccharomyces cerevisiae
Rho-type GTPase Rho5p by phosphorylation and ubiquitination. Rho5p binds to Ste50p, and the expression of the activated
RHO5
(
Q91H
) allele in an Δ
ste50
strain is lethal under conditions of osmotic stress. An overexpression screen identified
RGD2
and
MSI1
as being high-copy suppressors of the osmotic sensitivity of this lethality. Rgd2p had been identified as being a possible Rho5p GTPase-activating protein based on an in vitro assay; this result supports its function as a regulator of Rho5p activity in vivo.
MSI1
was previously identified as being a suppressor of hyperactive Ras/cyclic AMP signaling, where it antagonizes Npr1p kinase activity and promotes ubiquitination. Here, we show that Msi1p also acts via Npr1p to suppress activated Rho5p signaling. Rho5p is ubiquitinated, and its expression is lethal in a strain that is compromised for proteasome activity. These data identify Rho5p as being a target of Msi1p/Npr1p regulation and describe a regulatory circuit involving phosphorylation and ubiquitination.
Polo-Like Kinase Is Expressed in S/G
2
/M Phase and Associated with the Flagellum Attachment Zone in both Procyclic and Bloodstream Forms of
Trypanosoma brucei
Authors: Umeyama Takashi , Wang Ching C. 
Published: July 2008

ABSTRACT

Trypanosoma brucei
, the etiologic agent of African sleeping sickness, divides into insect (procyclic) and bloodstream forms. These two forms are subject to distinct cell cycle regulations, with cytokinesis controlled primarily by basal body/kinetoplast segregation in the procyclic form but by mitosis in the bloodstream form. Polo-like kinases (PLKs), known to play essential roles in regulating both mitosis and cytokinesis among eukaryotes, have a homologue in
T
.
brucei
, TbPLK, which regulates only cytokinesis. In our previous study, overexpressed triply hemagglutinin-tagged TbPLK (TbPLK-3HA) in the procyclic form localized to a mid-dorsal point and the anterior tip of the cell along the flagellum attachment zone (FAZ). In our current study, TbPLK-3HA expressed at the endogenous level was identified at the same dorsal location of both procyclic and bloodstream forms, albeit it was no longer detectable at the anterior tip of the cell. Endogenously expressed TbPLK fused with an enhanced yellow fluorescent protein (EYFP) localized to the same dorsal location along the FAZs in living procyclic and bloodstream cells. Fluorescence-activated cell sorter analysis of hydroxyurea-synchronized procyclic cells revealed that TbPLK-EYFP emerges during S phase, persists through G
2
/M phase, and vanishes in G
1
phase. An indicated TbPLK-EYFP association with the FAZs of G
2
/M cells may thus represent a timely localization to a potential initiation site of cytokinesis, which agrees with the recognized role of TbPLK in cytokinetic initiation.
Molecular Phylogenetic Analysis of a Geographically and Temporally Matched Set ofCandida albicansIsolates from Humans and Nonmigratory Wildlife in Central Illinois
Authors: Wrobel Lauren , Whittington Julia K. , Pujol Claude , Oh Soon-Hwan , Ruiz Marilyn O. , Pfaller Michael A. , Diekema Daniel J. , Soll David R. , Hoyer Lois L. 
Published: July 2008

ABSTRACTThis study explored whether wildlife species serve as the reservoir for humanCandida albicansstrains in a given geographic area.C.albicansisolates were collected from nonmigratory wildlife admitted to the University of Illinois Wildlife Medical Clinic. A geographically and temporally matched set ofC.albicansoral isolates was collected from healthy human volunteers. Multilocus sequence typing was used to assign strains to genetic clades. Clade 1 isolates, particularly diploid sequence type 69 (DST 69), were most common in humans. Clade 1 strains were less frequently recovered from wildlife, while clade 8 strains, particularly DST 90, were overrepresented in the wildlife collection. All instances where a wildlife and human isolate shared the same DST occurred within clade 1. Clade distributions between human and wildlife isolates were significantly different, demonstrating population isolation between the groups. These differences may indicate limited strain transfer between groups or differential selection ofC.albicansisolates in humans and wildlife. Wildlife strains had an amphotericin B MIC significantly lower than that of human isolates; strains with increased susceptibility were from several clades.C.albicansisolates were collected from domestic animals to provide comparisons with human and wildlife data sets.C.albicansisolation from canine and feline oral and anal swabs was infrequent; companion animal isolates were closely related to clade 1 human isolates. Collectively, the data suggest a greater likelihood ofC.albicanstransfer from humans to animals than from animals to humans. The nontransient human population may maintain the connection between geography and theC.albicansgenetic groups recovered from humans.
Regulation of the Subcellular Localization of Cyclic AMP-Dependent Protein Kinase in Response to Physiological Stresses and Sexual Differentiation in the Fission Yeast
Schizosaccharomyces pombe
Authors: Matsuo Yasuhiro , McInnis Brittney , Marcus Stevan 
Published: July 2008

ABSTRACT

We describe regulation of the subcellular localization of cyclic AMP (cAMP)-dependent protein kinase (PKA) regulatory (Cgs1p) and catalytic (Pka1p) subunits in the fission yeast
Schizosaccharomyces pombe
in response to physiological stresses and during sexual differentiation as determined by fluorescence microscopy of the Cgs1-green fluorescent protein (GFP) and Pka1-GFP fusion proteins, respectively. In wild-type
S. pombe
cells cultured to log phase under normal growth conditions, Cgs1p and Pka1p are concentrated in the nucleus and more diffusely present in the cytoplasm. Nuclear localization of both proteins is dependent on cAMP, since in cells lacking adenylate cyclase they are detectable only in the cytoplasm. In cells lacking Cgs1p or both Cgs1p and adenylate cyclase, Pka1p is concentrated in the nucleus, demonstrating a role for Cgs1p in the nuclear exclusion of Pka1p. Nuclear-cytoplasmic redistribution of Cgs1p and Pka1p is triggered by growth in glucose-limited or hyperosmotic media and in response to stationary-phase growth. In addition, both proteins are excluded from the nucleus in mating cells undergoing karyogamy and subsequently concentrated in postmeiotic spores. Cgs1p is required for subcellular redistribution of Pka1p induced by growth in glucose-limited and hyperosmotic media and during karyogamy but is not required for Pka1p redistribution triggered by stationary-phase growth or for the enrichment of Pka1p in spores. Our results demonstrate that PKA localization is regulated by cAMP and regulatory subunit-dependent and -independent mechanisms in
S. pombe
.
Analysis of a Growth-Phase-Regulated Two-Component Regulatory System in the Periodontal Pathogen
Treponema denticola
Authors: Frederick Jesse R. , Rogers Elizabeth A. , Marconi Richard T. 
Published: July 2008

ABSTRACT

Nothing is currently known regarding the global regulatory networks of
Treponema denticola
and other oral spirochetes. In this report, we assess the properties and potential phosphotransfer capability of a putative two-component regulatory system (TCS) of
T. denticola
that is formed by the products of open reading frames tde0032 (a sensor kinase) and tde0033 (a response regulator), henceforth designated AtcS and AtcR, respectively. Using PCR and DNA sequence analyses,
atcS
and
atcR
were demonstrated to be widely distributed and conserved among
T. denticola
isolates. Reverse transcription-PCR (RT-PCR) analyses revealed that these genes are cotranscribed and may also be expressed as part of a larger operon that includes several flanking genes. Analyses using 5′ rapid amplification of cDNA ends identified the transcriptional start sites for these operons and provided evidence that some of these genes may be independently transcribed from internal promoters. Real-time RT-PCR and Western blot analysis revealed significant upregulation of
atcRS
during late-stage growth, indicating growth-phase-dependent expression. Lastly, the phosphorelay capability of the AtcRS system was assessed and demonstrated using recombinant proteins. AtcS was found to undergo autophosphorylation and to transfer phosphate to AtcR. These analyses represent the first description of a functional TCS in an oral spirochetes and provide insight into the transcriptional regulatory mechanisms of these important bacteria.
Characterization of the Accessory Sec System of
Staphylococcus aureus
Authors: Siboo Ian R. , Chaffin Donald O. , Rubens Craig E. , Sullam Paul M. 
Published: July 2008

ABSTRACT

The SraP adhesin of
Staphylococcus aureus
is a member of a highly conserved family of serine-rich surface glycoproteins of gram-positive bacteria. For streptococci, export of the SraP homologs requires a specialized transport pathway (the accessory Sec system). Compared to streptococci, however, SraP is predicted to differ in its signal peptide and glycosylation, which may affect its dependence on a specialized system for transport. In addition, two genes (
asp4
and
asp5
) essential for export in
Streptococcus gordonii
are missing in
S. aureus
. Thus, the selectivity of the accessory Sec system in
S. aureus
may also differ compared to streptococci. To address these issues, the five genes encoding the putative accessory Sec system (
secY2
,
secA2
, and
asp1-3
) were disrupted individually in
S. aureus
ISP479C, and the resultant mutants were examined for SraP export. Disruption of
secA2
resulted in the near complete loss of SraP surface expression. Similar results were seen with disruption of
secY2
and
asp1
,
asp2
, or
asp3
. To assess whether the accessory Sec system transported other substrates, we compared secreted proteomes of ISP479C and a
secA2
isogenic mutant, by two-dimensional fluorescence difference gel electrophoresis. Although two consistent differences in proteome content were noted between the strains, neither protein appeared to be a likely substrate for accessory Sec export. Thus, the accessory Sec system of
S. aureus
is required for the export of SraP, and it appears to be dedicated to the transport of this substrate exclusively.
Salmonella enterica
Serovar Gallinarum Requires ppGpp for Internalization and Survival in Animal Cells
Authors: Jeong Jae-Ho , Song Miryoung , Park Sang-Ik , Cho Kyoung-Oh , Rhee Joon Haeng , Choy Hyon E. 
Published: July 2008

ABSTRACT

To elucidate the pathogenic mechanism of
Salmonella enterica
serovar Gallinarum, we examined the expression of the genes encoded primarily in
Salmonella
pathogenicity island 1 (SPI-1) and SPI-2. These genes were found to be induced as cultures entered stationary phase under high- and low-oxygen growth conditions, as also observed for
Salmonella
serovar Typhimurium. In contrast,
Salmonella
serovar Gallinarum in the exponential growth phase most efficiently internalized cultured animal cells. Analysis of mutants defective in SPI-1 genes, SPI-2 genes, and others implicated in early stages of infection revealed that SPI-1 genes were not involved in the internalization of animal cells by
Salmonella
serovar Gallinarum. Following entry, however,
Salmonella
serovar Gallinarum was found to reside in LAMP1-positive vacuoles in both phagocytic and nonphagocytic cells, although internalization was independent of SPI-1. A mutation that conferred defects in ppGpp synthesis was the only one found to affect animal cell internalization by
Salmonella
serovar Gallinarum. It was concluded that
Salmonella
serovar Gallinarum internalizes animal cells by a mechanism independent of SPI-1 genes but dependent on ppGpp. Intracellular growth also required ppGpp for the transcription of genes encoded in SPI-2.
Artificial Septal Targeting ofBacillus subtilisCell Division Proteins inEscherichia coli: an Interspecies Approach to the Study of Protein-Protein Interactions in Multiprotein Complexes
Authors: Robichon Carine , King Glenn F. , Goehring Nathan W. , Beckwith Jon 
Published: July 2008

ABSTRACTBacterial cell division is mediated by a set of proteins that assemble to form a large multiprotein complex called the divisome. Recent studies inBacillus subtilisandEscherichia coliindicate that cell division proteins are involved in multiple cooperative binding interactions, thus presenting a technical challenge to the analysis of these interactions. We report here the use of anE. coliartificial septal targeting system for examining the interactions between theB. subtiliscell division proteins DivIB, FtsL, DivIC, and PBP 2B. This technique involves the fusion of one of the proteins (the “bait”) to ZapA, anE. coliprotein targeted to mid-cell, and the fusion of a second potentially interacting partner (the “prey”) to green fluorescent protein (GFP). A positive interaction between two test proteins inE. colileads to septal localization of the GFP fusion construct, which can be detected by fluorescence microscopy. Using this system, we present evidence for two sets of strong protein-protein interactions betweenB. subtilisdivisomal proteins inE. coli, namely, DivIC with FtsL and DivIB with PBP 2B, that are independent of otherB. subtiliscell division proteins and that do not disturb the cytokinesis process in the host cell. Our studies based on the coexpression of three or four of theseB. subtiliscell division proteins suggest that interactions among these four proteins are not strong enough to allow the formation of a stable four-protein complex inE. coliin contrast to previous suggestions. Finally, our results demonstrate thatE. coliartificial septal targeting is an efficient and alternative approach for detecting and characterizing stable protein-protein interactions within multiprotein complexes from other microorganisms. A salient feature of our approach is that it probably only detects the strongest interactions, thus giving an indication of whether some interactions suggested by other techniques may either be considerably weaker or due to false positives.
Excess SeqA Leads to Replication Arrest and a Cell Division Defect inVibrio cholerae
Authors: Saint-Dic Djenann , Kehrl Jason , Frushour Brian , Kahng Lyn Sue 
Published: July 2008

ABSTRACTAlthough most bacteria contain a single circular chromosome, some have complex genomes, and allVibriospecies studied so far contain both a large and a small chromosome. In recent years, the divided genome ofVibrio choleraehas proven to be an interesting model system with both parallels to and novel features compared with the genome ofEscherichia coli. While factors influencing the replication and segregation of both chromosomes have begun to be elucidated, much remains to be learned about the maintenance of this genome and of complex bacterial genomes generally. An important aspect of replicating any genome is the correct timing of initiation, without which organisms risk aneuploidy. During DNA replication inE. coli, newly replicated origins cannot immediately reinitiate because they undergo sequestration by the SeqA protein, which binds hemimethylated origin DNA. This DNA is already methylated by Dam on the template strand and later becomes fully methylated; aberrant amounts of Dam or the deletion ofseqAleads to asynchronous replication. In our study, hemimethylated DNA was detected at both origins ofV. cholerae, suggesting that these origins are also subject to sequestration. The overproduction of SeqA led to a loss of viability, the condensation of DNA, and a filamentous morphology. Cells with abnormal DNA content arose in the population, and replication was inhibited as determined by a reduced ratio of origin to terminus DNA in SeqA-overexpressing cells. Thus, excessive SeqA negatively affects replication inV. choleraeand prevents correct progression to downstream cell cycle events such as segregation and cell division.
Membrane Morphology and Leukotoxin Secretion Are Associated with a Novel Membrane Protein ofAggregatibacter actinomycetemcomitans
Authors: Gallant Claude V. , Sedic Maja , Chicoine Erin A. , Ruiz Teresa , Mintz Keith P. 
Published: July 2008

ABSTRACTGram-negative bacteria display either a flat or an irregular outer membrane. The periodontal pathogenAggregatibacter(Actinobacillus)actinomycetemcomitanshas an irregular outer membrane. We have identified a gene that is associated with the biogenesis of this morphology. The gene is part of a three-gene operon and codes for a 141-kDa protein designated morphogenesis protein C (MorC), which is conserved in several gram-negative bacteria includingHaemophilus influenzaeandPasteurella multocida. Insertional inactivation of this gene resulted in the conversion of an irregularly shaped membrane to a flat membrane. Associated with this morphological change were the autoaggregation of the bacteria during planktonic growth and a concomitant increase in the surface hydrophobicity of the bacterium. The absence of MorC also resulted in the loss of the secretion of leukotoxin but not theltxAtranscription. Our findings suggest that MorC is critical for membrane morphology and leukotoxin secretion inA. actinomycetemcomitans.