bluuebunny/crossref_metadata_2025 huggingface dataset:
Short‐term study of infliximab treatment for Crohn's disease in China
Authors: ZHENG Jia Ju , ZHI Pang , WANG Yu Ming , ZHU Fan , GU Wei , XING Yi Chen , ZHOU Chun Li , SHEN Bi Wu
Published: January 2011

OBJECTIVE:  To determine the effectiveness and safety of short‐term treatment of infliximab (IFX) in a group of Chinese patients with active Crohn's disease (CD).

METHODS:  Patients with established diagnosis of active CD were treated with IFX intravenously with a dose of 5 mg/kg at week 0, 2, 6. Clinical assessments were performed at baseline (week 0) and every week after IFX infusion until 8 weeks after the induction dose.

RESULTS:  Fourteen patients (nine male, five female) with a mean age of 29.7 years (range from 15 to 65 years) were included in the analysis. The mean subjective scores were decreased from 2.85 ± 0.57 at baseline to 1.3 ± 0.4 at week 14 (P < 0.05). The mean Harvey‐Bradshaw index was 7.9 ± 1.5 at baseline and 2.3 ± 1.0 at week 14. The levels of erythrocyte sedimentation rate, serum C‐reactive protein, total protein (TP) and albumin (ALB) were significantly improved during the 14‐week period. Colonoscopy showed a remarkable improvement. Mild and transient adverse events including skin itching, headache and elevation of serum alanine aminotransferase and aspartate transaminase were each observed in one patient. Severe anemia, leucopenia and thrombocytopenia at week 27 after three infusions of IFX were observed in one patient.

CONCLUSIONS:  Treatment with three infusions of IFX at a dose of 5 mg/kg was effective for induction of remission for active CD patients who failed to respond to conventional therapies. Study of long‐term efficacy and safety of IFX therapy is warranted for further investigations.
Correlation of the expression of toll‐like receptors in monocyte‐derived dendritic cells with prognosis of chronic severe hepatitis B
Authors: LI Ning , CHEN Ming Quan , QIAN Zhi Ping , ZHU Meng Qi , LI Qian , ZHENG Jian Ming , WANG Xin Yu , SHI Guang Feng
Published: January 2011

OBJECTIVE: This study aims to measure the expression of toll‐like receptors (TLR) in monocyte‐derived dendritic cells (MoDC) from chronic severe hepatitis B (CSHB), to assess the contribution of TLRs in CSHB.

METHODS: Peripheral blood was collected from 40 CSHB patients, 30 chronic hepatitis B (CHB) patients, and 30 healthy individuals who served as healthy controls (HCs). Purified monocytes were isolated by a combination of Histopaque‐1.077 and CD14 Microbeads. MoDCs were induced with granulocyte macrophage colony‐stimulating factor and interleukin‐4 for 6 days from CD14+monocytes. The expression of TLRs in MoDC was measured using real‐time PCR and flow cytometry.

RESULTS: The expressions of TLR‐1, ‐2, ‐7 were significantly higher in MoDC of CSHB than that of HCs, of which the level of TLR‐3 was decreased. Particularly in CSHB patients, the TLR‐3 expression was further decreased compared to CHB patients. In non‐survival CSHB patients, TLR‐3 level was significantly decreased, while TLR‐2 expression was dramatically increased. Linear correlation analysis demonstrated significant correlations between TLR‐3 level and disease severity markers (total bilirubin, prothrombin activity, creatinine, white blood cell count, and maximum volume of ascitic fluid) in individual CSHB patients.

CONCLUSIONS: TLR‐2 and TLR‐3 may be involved in the pathogenesis of CSHB, and TLR‐3 may influence the prognosis of CSHB.
Identification of Anaplasma spp. Rickettsia Isolated from Horses from Clinical Disease Cases in Poland
Authors: Adaszek Ł. , Winiarczyk S.
Published: February 2011

This study was aimed at determining the cause of the diseases in five horses exhibiting symptoms of fever, joint oedema and ataxia and thrombocytopenia. The PCR technique revealed the presence in the blood of 16S RNA Anaplasma/Ehrlichia spp. genetic material. DNA amplification with primers EHR 521 and EHR 747 gave a product with a size of 247 bp. The sequence of the PCR product obtained showed a 97.6–99.6% similarity with a sequence of a fragment of 16S RNA Anaplasma phagocytophilum, gene number EU 090186 from GenBank. Intravenous administration of oxytetracycline at a dose of 8 mg/kg of body mass for 7 days resulted in a gradual recovery.
Intramyocardial administration of chimeric ephrinA1‐Fc promotes tissue salvage following myocardial infarction in mice
Authors: Dries Jessica L. , Kent Susan D. , Virag Jitka A. I.
Published: February 2011

Non‐technical summary  Following a myocardial infarction, cardiac muscle becomes irreversibly damaged and over time this may lead to heart failure. Strategies to reduce ischaemic damage, enhance new vessel growth, and/or replace damaged heart muscle are currently being investigated. We have identified a novel non‐angiogenic role for ephrinA1, a membrane‐bound ligand receptor tyrosine kinase, in promoting myocardial tissue salvage after non reperfused myocardial infarction. Treating the heart with this protein at the time of injury reduced infarct size and overall damage, presumably by preventing cardiomyocyte loss after ischaemia. Further studies are in progress to determine the cellular mechanisms by which this occurs and the extent to which adverse remodelling is attenuated.
In Vitro Validation of Finite-Element Model of AAA Hemodynamics Incorporating Realistic Outlet Boundary Conditions
Authors: Kung Ethan O. , Les Andrea S. , Medina Francisco , Wicker Ryan B. , McConnell Michael V. , Taylor Charles A.
Published: February 2011

The purpose of this study is to validate numerical simulations of flow and pressure in an abdominal aortic aneurysm (AAA) using phase-contrast magnetic resonance imaging (PCMRI) and an in vitro phantom under physiological flow and pressure conditions. We constructed a two-outlet physical flow phantom based on patient imaging data of an AAA and developed a physical Windkessel model to use as outlet boundary conditions. We then acquired PCMRI data in the phantom while it operated under conditions mimicking a resting and a light exercise physiological state. Next, we performed in silico numerical simulations and compared experimentally measured velocities, flows, and pressures in the in vitro phantom to those computed in the in silico simulations. There was a high degree of agreement in all of the pressure and flow waveform shapes and magnitudes between the experimental measurements and simulated results. The average pressures and flow split difference between experiment and simulation were all within 2%. Velocity patterns showed good agreement between experimental measurements and simulated results, especially in the case of whole-cycle averaged comparisons. We demonstrated methods to perform in vitro phantom experiments with physiological flows and pressures, showing good agreement between numerically simulated and experimentally measured velocity fields and pressure waveforms in a complex patient-specific AAA geometry.
Role of
Klebsiella pneumoniae
LamB Porin in Antimicrobial Resistance
Authors: García-Sureda Laura , Juan Carlos , Doménech-Sánchez Antonio , Albertí Sebastián
Published: February 2011

To investigate the contribution of LamB in
Klebsiella pneumoniae
antimicrobial resistance, we determined the MICs of various antibiotics and the frequency of mutation to increased cefoxitin or meropenem resistance of the strains CSUB10S (expressing only OmpK36), CSUB10R (lacking OmpK35 and OmpK36), and their derived isogenic insertion-duplication mutants deficient in LamB. Expression of LamB was indispensable in order for CSUB10S to lose OmpK36 and become resistant to cefoxitin, while in CSUB10R, LamB deficiency promoted increased resistance to carbapenem.
Successful Treatment of Old World Cutaneous Leishmaniasis Caused by
Leishmania infantum
with Posaconazole
Authors: Paniz Mondolfi A. E. , Stavropoulos C. , Gelanew T. , Loucas E. , Perez Alvarez A. M. , Benaim G. , Polsky B. , Schoenian G. , Sordillo E. M.
Published: February 2011

Old World cutaneous leishmaniasis is a widespread and potentially disfiguring protozoal infection that is endemic in the Mediterranean basin, Africa, and parts of Asia. Human infection is caused by several species of
Leishmania
parasites, such as
Leishmania infantum
. Available systemic and topical treatments vary in efficacy and are often unjustified due to their toxicity. We report on a case that was treated with posaconazole, a drug typically considered an antifungal agent but which also targets specific metabolic pathways of the parasite.
Development of an Antivirulence Drug against
Streptococcus mutans
: Repression of Biofilm Formation, Acid Tolerance, and Competence by a Histidine Kinase Inhibitor, Walkmycin C
Authors: Eguchi Yoko , Kubo Norihiro , Matsunaga Hiroko , Igarashi Masayuki , Utsumi Ryutaro
Published: February 2011

Two-component signal transduction systems (TCSs) in prokaryotes often regulate gene clusters that induce pathogenicity, and thus they have frequently been proposed as potential drug targets for attenuating the virulence of pathogens. The pathogenic potential of
Streptococcus mutans
, the major etiological pathogen of dental caries, is also regulated by its TCSs. The object of this study was to evaluate the effect of a histidine kinase (HK) inhibitor against two major virulence factors of
S. mutans
: biofilm formation and acid tolerance. Walkmycin C (WKM C), an HK inhibitor isolated from the screening of inhibitors against WalK HK in
Bacillus subtilis
, inhibited the
in vitro
autophosphorylation activity of three purified
S. mutans
HKs, i.e., VicK, CiaH, and LiaS. Although
S. mutans
does not have any essential HK but only an essential response regulator, VicR, WKM C showed an MIC of 6.25 μg/ml. This inhibitory effect of WKM C suggests that blocking the autophosphorylation of multiple HKs may inhibit phosphotransfer to VicR from VicK and other HKs. When WKM C was added at sub-MIC levels, the cells formed abnormal biofilms and also showed a defect in competence. When the cells were pretreated with WKM C, an increase in acid sensitivity was observed. Our results show that WKM C represses two pathogenic phenotypes of
S. mutans
, indicating the possibility of developing histidine kinase inhibitors into antivirulence drugs.
Fecal Bacteroidales Diversity and Decay in Response to Variations in Temperature and Salinity
Authors: Schulz Christopher J. , Childers Gary W.
Published: January 2011

Bacteroidales
are attractive as water quality indicators because of their potential to discern sources of fecal pollution, and it is presumed that these bacteria do not multiply outside their host organisms. The persistence of a fecal
Bacteroidales
marker was monitored over 14 days in river water microcosms that varied in temperature from 10°C to 30°C and salinity from 0‰ to 30‰ by quantitative PCR (qPCR). Decay rates were estimated and compared to the results of other studies examining the survival and persistence of
Bacteroidales
markers by converting decay rates from other studies to a common decay rate unit. The log-linear decay rates estimated in this work ranged from −0.18 to −1.31 ln(
C

T

/
C
0
) day
−1
, where
C

T

is the threshold cycle and
C
0
is the concentration of cells at time zero, which is comparable to findings in previous studies. Salinity had a positive effect on
Bacteroidales
marker persistence, while decay was more rapid at higher temperatures. Comparison of 16S rRNA gene clone libraries generated from microcosm samples indicated that most of the operational taxonomic unit (OTU) and phylogenetic diversity was found within samples and not between samples, indicating at least qualitatively that diverse lineages persist and likely have similar survival characteristics under most of the conditions examined. It was noted that the samples at higher salinities also had the smallest amount of diversity between samples as well as the lowest decay rates. This research also highlights the need for a repository of raw survival and persistence data if more sophisticated models of decay are to be employed and compared between different studies.
Field Detection of
Schistosoma japonicum
Cercariae in Environmental Water Samples by Quantitative PCR
Authors: Worrell Caitlin , Xiao Ning , Vidal Jorge E. , Chen Lin , Zhong Bo , Remais Justin
Published: January 2011

A species-specific quantitative PCR (qPCR) assay was combined with two novel water-sampling methods and compared with the mouse bioassay for the quantitative detection of
S. japonicum
in surface waters. The novel methods were capable of capturing cercariae and, with subsequent analysis through qPCR, detecting the presence of a minimum of 1 cercaria.
Campylobacter troglodytis
sp. nov., Isolated from Feces of Human-Habituated Wild Chimpanzees (
Pan troglodytes schweinfurthii
) in Tanzania
Authors: Kaur Taranjit , Singh Jatinder , Huffman Michael A. , Petrželková Klára J. , Taylor Nancy S. , Xu Shilu , Dewhirst Floyd E. , Paster Bruce J. , Debruyne Lies , Vandamme Peter , Fox James G.
Published: January 2011

The transmission of simian immunodeficiency and Ebola viruses to humans in recent years has heightened awareness of the public health significance of zoonotic diseases of primate origin, particularly from chimpanzees. In this study, we analyzed 71 fecal samples collected from 2 different wild chimpanzee (
Pan troglodytes
) populations with different histories in relation to their proximity to humans.
Campylobacter
spp. were detected by culture in 19/56 (34%) group 1 (human habituated for research and tourism purposes at Mahale Mountains National Park) and 0/15 (0%) group 2 (not human habituated but propagated from an introduced population released from captivity over 30 years ago at Rubondo Island National Park) chimpanzees, respectively. Using 16S rRNA gene sequencing, all isolates were virtually identical (at most a single base difference), and the chimpanzee isolates were most closely related to
Campylobacter helveticus
and
Campylobacter upsaliensis
(94.7% and 95.9% similarity, respectively). Whole-cell protein profiling, amplified fragment length polymorphism analysis of genomic DNA,
hsp60
sequence analysis, and determination of the mol% G+C content revealed two subgroups among the chimpanzee isolates. DNA-DNA hybridization experiments confirmed that both subgroups represented distinct genomic species. In the absence of differential biochemical characteristics and morphology and identical 16S rRNA gene sequences, we propose to classify all isolates into a single novel nomenspecies,
Campylobacter troglodytis
, with strain MIT 05-9149 as the type strain; strain MIT 05-9157 is suggested as the reference strain for the second
C. troglodytis
genomovar. Further studies are required to determine whether the organism is pathogenic to chimpanzees and whether this novel
Campylobacter
colonizes humans and causes enteric disease.
Strong and Consistently Synergistic Inactivation of Spores of Spoilage-AssociatedBacillusandGeobacillusspp. by High Pressure and Heat Compared with Inactivation by Heat Alone
Authors: Olivier S. A. , Bull M. K. , Stone G. , van Diepenbeek R. J. , Kormelink F. , Jacops L. , Chapman B.
Published: January 2011

The inactivation of spores of four low-acid food spoilage organisms by high pressure thermal (HPT) and thermal-only processing was compared on the basis of equivalent thermal lethality calculated at a reference temperature of 121.1°C (Fz121.1°C, 0.1 MPa or 600 MPa) and characterized as synergistic, not different or protective. In addition, the relative resistances of spores of the different spoilage microorganisms to HPT processing were compared. Processing was performed and inactivation was compared in both laboratory and pilot scale systems and in model (diluted) and actual food products. Where statistical comparisons could be made, at least 4 times and up to around 190 times more inactivation (log10reduction/minute atFTz121.1°C) of spores ofBacillus amyloliquefaciens,Bacillus sporothermodurans, andGeobacillus stearothermophiluswas achieved using HPT, indicating a strong synergistic effect of high pressure and heat.Bacillus coagulansspores were also synergistically inactivated in diluted and undiluted Bolognese sauce but were protected by pressure against thermal inactivation in undiluted cream sauce. Irrespective of the response characterization,B. coagulansandB. sporothermoduranswere identified as the most HPT-resistant isolates in the pilot scale and laboratory scale studies, respectively, andG. stearothermophilusas the least in both studies and all products. This is the first study to comprehensively quantitatively characterize the responses of a range of spores of spoilage microorganisms as synergistic (or otherwise) using an integrated thermal-lethality approach (FTz). The use of theFTzapproach is ultimately important for the translation of commercial minimum microbiologically safe and stable thermal processes to HPT processes.
Indirect Modulation of the Intracellular c-Di-GMP Level in
Shewanella oneidensis
MR-1 by MxdA
Authors: Rakshe Shauna , Leff Maija , Spormann Alfred M.
Published: January 2011

The GGDEF domain protein MxdA, which is important for biofilm formation in
Shewanella oneidensis
MR-1, was hypothesized to possess diguanylate cyclase activity. Here, we demonstrate that while MxdA controls the cellular level of c-di-GMP in
S. oneidensis
, it modulates the c-di-GMP pool indirectly.
Proteomic and Transcriptomic Elucidation of the Mutant
Ralstonia eutropha
G
+
1 with Regard to Glucose Utilization
Authors: Raberg Matthias , Peplinski Katja , Heiss Silvia , Ehrenreich Armin , Voigt Birgit , Döring Christina , Bömeke Mechthild , Hecker Michael , Steinbüchel Alexander
Published: January 2011

By taking advantage of the available genome sequence of
Ralstonia eutropha
H16, glucose uptake in the UV-generated glucose-utilizing mutant
R. eutropha
G
+
1 was investigated by transcriptomic and proteomic analyses. Data revealed clear evidence that glucose is transported by a usually
N
-acetylglucosamine-specific phosphotransferase system (PTS)-type transport system, which in this mutant is probably overexpressed due to a derepression of the encoding
nag
operon by an identified insertion mutation in gene H16_A0310 (
nagR
). Furthermore, a missense mutation in
nagE
(membrane component EIICB), which yields a substitution of an alanine by threonine in NagE and may additionally increase glucose uptake, was identified. Phosphorylation of glucose is subsequently mediated by NagF (cytosolic PTS component EIIA-HPr-EI) or glucokinase (GlK), respectively. The inability of the defined deletion mutant
R. eutropha
G
+
1 Δ
nagFEC
to utilize glucose strongly confirms this finding. In addition, secondary effects of glucose, which is now intracellularly available as a carbon source, on the metabolism of the mutant cells in the stationary growth phase occurred: intracellular glucose degradation is stimulated by the stronger expression of enzymes involved in the 2-keto-3-deoxygluconate 6-phosphate (KDPG) pathway and in subsequent reactions yielding pyruvate. The intermediate phosphoenolpyruvate (PEP) in turn supports further glucose uptake by the Nag PTS. Pyruvate is then decarboxylated by the pyruvate dehydrogenase multienzyme complex to acetyl coenzyme A (acetyl-CoA), which is directed to poly(3-hydroxybutyrate). The polyester is then synthesized to a greater extent, as also indicated by the upregulation of various enzymes of poly-β-hydroxybutyrate (PHB) metabolism. The larger amounts of NADPH required for PHB synthesis are delivered by significantly increased quantities of proton-translocating NAD(P) transhydrogenases. The current study successfully combined transcriptomic and proteomic investigations to unravel the phenotype of this hitherto-undefined glucose-utilizing mutant.
Prevalence, Development, and Molecular Mechanisms of Bacteriocin Resistance in
Campylobacter
Authors: Hoang Ky Van , Stern Norman J. , Saxton Arnold M. , Xu Fuzhou , Zeng Ximin , Lin Jun
Published: January 2011

Bacteriocins (BCNs) are antimicrobial peptides produced by bacteria with narrow or broad spectra of antimicrobial activity. Recently, several unique anti-
Campylobacter
BCNs have been identified from commensal bacteria isolated from chicken intestines. These BCNs dramatically reduced
C. jejuni
colonization in poultry and are being directed toward on-farm control of
Campylobacter
. However, no information concerning prevalence, development, and mechanisms of BCN resistance in
Campylobacter
exists. In this study, susceptibilities of 137
C. jejuni
isolates and 20
C. coli
isolates to the anti-
Campylobacter
BCNs OR-7 and E-760 were examined. Only one
C. coli
strain displayed resistance to the BCNs (MIC, 64 μg/ml), while others were susceptible, with MICs ranging from 0.25 to 4 μg/ml. The
C. coli
mutants resistant to BCN OR-7 also were obtained by
in vitro
selection, but all displayed only low-level resistance to OR-7 (MIC, 8 to 16 μg/ml). The acquired BCN resistance in
C. coli
could be transferred at intra- and interspecies levels among
Campylobacter
strains by biphasic natural transformation. Genomic examination of the OR-7-resistant mutants by using DNA microarray and random transposon mutagenesis revealed that the multidrug efflux pump CmeABC contributes to both intrinsic resistance and acquired resistance to the BCNs. Altogether, this study represents the first report of and a major step forward in understanding BCN resistance in
Campylobacter
, which will facilitate the development of effective BCN-based strategies to reduce the
Campylobacter
loads in poultry.
Iodide Accumulation by Aerobic Bacteria Isolated from Subsurface Sediments of a
129
I-Contaminated Aquifer at the Savannah River Site, South Carolina
Authors: Li Hsiu-Ping , Brinkmeyer Robin , Jones Whitney L. , Zhang Saijin , Xu Chen , Schwehr Kathy A. , Santschi Peter H. , Kaplan Daniel I. , Yeager Chris M.
Published: January 2011

129
I is of major concern because of its mobility in the environment, excessive inventory, toxicity (it accumulates in the thyroid), and long half-life (∼16 million years). The aim of this study was to determine if bacteria from a
129
I-contaminated oxic aquifer at the F area of the U.S. Department of Energy's Savannah River Site, SC, could accumulate iodide at environmentally relevant concentrations (0.1 μM I
−
). Iodide accumulation capability was found in 3 out of 136 aerobic bacterial strains isolated from the F area that were closely related to
Streptomyces
/
Kitasatospora
spp.,
Bacillus mycoides
, and
Ralstonia/Cupriavidus
spp. Two previously described iodide-accumulating marine strains, a
Flexibacter aggregans
strain and an
Arenibacter troitsensis
strain, accumulated 2 to 50% total iodide (0.1 μM), whereas the F-area strains accumulated just 0.2 to 2.0%. Iodide accumulation by FA-30 was stimulated by the addition of H
2
O
2
, was not inhibited by chloride ions (27 mM), did not exhibit substrate saturation kinetics with regard to I
−
concentration (up to 10 μM I
−
), and increased at pH values of <6. Overall, the data indicate that I
−
accumulation likely results from electrophilic substitution of cellular organic molecules. This study demonstrates that readily culturable, aerobic bacteria of the F-area aquifer do not accumulate significant amounts of iodide; however, this mechanism may contribute to the long-term fate and transport of
129
I and to the biogeochemical cycling of iodine over geologic time.
Functional and Structural Microbial Diversity in Organic and Conventional Viticulture: Organic Farming Benefits Natural Biocontrol Agents
Authors: Schmid Florian , Moser Gerit , Müller Henry , Berg Gabriele
Published: January 2011

Statistically significant differences in the structure and function of above-ground grapevine-associated microorganisms from organically and conventionally managed vineyards were found.
Aureobasidium pullulans
, a copper-detoxifying fungus and biocontrol agent, plays a key role in explaining these differences. The black fungus was strongly enriched in the communities of organically managed plants and yielded a higher indigenous antiphytopathogenic potential.
LuxS Coexpression Enhances Yields of Recombinant Proteins in
Escherichia coli
in Part through Posttranscriptional Control of GroEL
Authors: Tsao Chen-Yu , Wang Liang , Hashimoto Yoshifumi , Yi Hyunmin , March John C. , DeLisa Matthew P. , Wood Thomas K. , Valdes James J. , Bentley William E.
Published: January 2011

Cell-to-cell communication, or quorum sensing (QS), enables cell density-dependent regulation of bacterial gene expression which can be exploited for the autonomous-signal-guided expression of recombinant proteins (C. Y. Tsao, S. Hooshangi, H. C. Wu, J. J. Valdes, and W. E. Bentley, Metab. Eng. 12:291-297, 2010). Earlier observations that the metabolic potential of
Escherichia coli
is conveyed via the QS signaling molecule autoinducer-2 (AI-2) suggested that the capacity for protein synthesis could also be affected by AI-2 signaling (M. P. DeLisa, J. J. Valdes, and W. E. Bentley, J. Bacteriol. 183:2918-2928, 2001). In this work, we found that simply adding conditioned medium containing high levels of AI-2 at the same time as inducing the synthesis of recombinant proteins doubled the yield of active product. We have hypothesized that AI-2 signaling “conditions” cells as a natural consequence of cell-to-cell communication and that this could tweak the signal transduction cascade to alter the protein synthesis landscape. We inserted
luxS
(AI-2 synthase) into vectors which cosynthesized proteins of interest (organophosphorus hydrolase [OPH], chloramphenicol acetyltransferase [CAT], or UV-variant green fluorescent protein [GFPuv]) and evaluated the protein expression in
luxS
-deficient hosts. In this way, we altered the level of
luxS
in the cells in order to “tune” the synthesis of AI-2. We found conditions in which the protein yield was dramatically increased. Further studies demonstrated coincident upregulation of the chaperone GroEL, which may have facilitated higher yields and is shown for the first time to be positively regulated at the posttranscriptional level by AI-2. This report is the first to demonstrate that the protein synthesis capacity of
E. coli
can be altered by rewiring quorum sensing circuitry.
Epidemiological Association of Different
Campylobacter jejuni
Groups with Metabolism-Associated Genetic Markers
Authors: Zautner Andreas E. , Herrmann Sahra , Corso Jasmin , Tareen A. Malik , Alter Thomas , Groß Uwe
Published: January 2011

In this study, multilocus sequence typing (MLST) was combined with the genetic detection of six genetic markers,
ansB
,
dmsA
,
ggt
,
cj1585c
,
cjj81176
-
1367/71
(
cj1365c
), and the two-gene marker
tlp7
(
cj0951c
plus
cj0952c
), to assess if their presence correlated with different
C. jejuni
clonal groups. Using a collection of 266
C. jejuni
isolates from (in decreasing order of sample size) humans, chickens, cattle, and turkeys, it was further investigated whether the resulting genotypes correlated with the isolation source. We found combinations of the six marker genes to be mutually exclusive, and their patterns of presence or absence correlated to some degree with animal source. Together with MLST results, the obtained genotypes could be segregated into six groups. An association was identified for
ansB
,
dmsA
, and
ggt
with the MLST-clonal complexes (MLST-CC) 22, 42, 45, and 283, which formed the most prominent group, in which chickens were the most prevalent animal source. Two other groups, characterized by the presence of
cj1585c
,
cjj81176
-
1367/71
, and the two-gene marker
tlp7
, associated with either MLST-CC 21 or 61, were overrepresented in isolates of bovine origin. Mutually exclusive marker gene combinations were observed for
ansB
,
dmsA
, and
ggt
, typically found in CC 45 and the related CC 22, 42, and 283, whereas the other three marker genes were found mostly in CC 21, 48, and 206. The presence of the two-gene marker
tlp7
, which is typical for MLST 21 and 53 as well as for MLST-CC 61, strongly correlates with a bovine host; this is interpreted as an example of host adaptation. In cases of
C. jejuni
outbreaks, these genetic markers could be helpful for more effective source tracking.
Ammonia-Oxidizing Bacteria in Biofilters Removing Trihalomethanes Are Related to
Nitrosomonas oligotropha
Authors: Wahman David G. , Kirisits Mary Jo , Katz Lynn E. , Speitel Gerald E.
Published: January 2011

Ammonia-oxidizing bacteria (AOB) in nitrifying biofilters degrading four regulated trihalomethanes—trichloromethane, bromodichloromethane, dibromochloromethane, and tribromomethane—were related to
Nitrosomonas oligotropha. N. oligotropha
is associated with chloraminated drinking water systems, and its presence in the biofilters might indicate that trihalomethane tolerance is another reason that this bacterium is dominant in chloraminated systems.
Impact of Sorbic Acid on Germinant Receptor-Dependent and -Independent Germination Pathways in
Bacillus cereus
Authors: van Melis C. C. J. , Nierop Groot M. N. , Abee T.
Published: January 2011

Amino acid- and inosine-induced germination of
Bacillus cereus
ATCC 14579 spores was reversibly inhibited in the presence of 3 mM undissociated sorbic acid. Exposure to high hydrostatic pressure, Ca-dipicolinic acid (DPA), and bryostatin, an activator of PrkC kinase, negated this inhibition, pointing to specific blockage of signal transduction in germinant receptor-mediated germination.
Deleterious Effect of the Q
o
Inhibitor Compound Resistance-Conferring Mutation G143A in the Intron-Containing Cytochrome
b
Gene and Mechanisms for Bypassing It
Authors: Vallières Cindy , Trouillard Martin , Dujardin Geneviève , Meunier Brigitte
Published: January 2011

The mutation G143A in the inhibitor binding site of cytochrome
b
confers a high level of resistance to fungicides targeting the
bc
1
complex. The mutation, reported in many plant-pathogenic fungi, has not evolved in fungi that harbor an intron immediately after the codon for G143 in the cytochrome
b
gene, intron bi2. Using
Saccharomyces
cerevisiae
as a model organism, we show here that a codon change from GGT to GCT, which replaces glycine 143 with alanine, hinders the splicing of bi2 by altering the exon/intron structure needed for efficient intron excision. This lowers the levels of cytochrome
b
and respiratory growth. We then investigated possible bypass mechanisms that would restore the respiratory fitness of a resistant mutant. Secondary mutations in the mitochondrial genome were found, including a point mutation in bi2 restoring the correct exon/intron structure and the deletion of intron bi2. We also found that overexpression of nuclear genes
MRS2
and
MRS3
, encoding mitochondrial metal ion carriers, partially restores the respiratory growth of the G143A mutant. Interestingly, the
MRS3
gene from the plant-pathogenic fungus
Botrytis
cinerea
, overexpressed in an
S
.
cerevisiae
G143A mutant, had a similar compensatory effect. These bypass mechanisms identified in yeast could potentially arise in pathogenic fungi.
Variable Infection Frequency and High Diversity of Multiple Strains of
Wolbachia pipientis
in
Perkinsiella
Planthoppers
Authors: Hughes G. L. , Allsopp P. G. , Brumbley S. M. , Woolfit M. , McGraw E. A. , O'Neill S. L.
Published: January 2011

This survey of
Wolbachia
infections in populations of the planthoppers
Perkinsiella saccharicida
and
Perkinsiella vitiensis
revealed variable frequencies, low-titer infections, and high phylogenetic diversities of strains. These observations add to the growing realization that
Wolbachia
infections may be extremely common within invertebrates and yet occur infrequently within populations and at low titer within individuals.
eIF2α Kinases Control Chalone Production in Dictyostelium discoideum
Authors: Bowman Robert L. , Xiong Yanhua , Kirsten Janet H. , Singleton Charles K.
Published: January 2011

Growing
Dictyostelium
cells secrete CfaD and AprA, two proteins that have been characterized as chalones. They exist within a high-molecular-weight complex that reversibly inhibits cell proliferation, but not growth, via cell surface receptors and a signaling pathway that includes G proteins. How the production of these two proteins is regulated is unknown.
Dictyostelium
cells possess three GCN2-type eukaryotic initiation factor 2 α subunit (eIF2α) kinases, proteins that phosphorylate the translational initiation factor eIF2α and possess a tRNA binding domain involved in their regulation. The
Dictyostelium
kinases have been shown to function during development in regulating several processes. We show here that expression of an unregulated, activated kinase domain greatly inhibits cell proliferation. The inhibitory effect on proliferation is not due to a general inhibition of translation. Instead, it is due to enhanced production of a secreted factor(s). Indeed, extracellular CfaD and AprA proteins, but not their mRNAs, are overproduced in cells expressing the activated kinase domain. The inhibition of proliferation is not seen when the activated kinase domain is expressed in cells lacking CfaD or AprA or in cells that contain a nonphosphorylatable eIF2α. We conclude that production of the chalones CfaD and AprA is translationally regulated by eIF2α phosphorylation. Both proteins are upregulated at the culmination of development, and this enhanced production is lacking in a strain that possesses a nonphosphorylatable eIF2α.
Role of the Npr1 Kinase in Ammonium Transport and Signaling by the Ammonium Permease Mep2 in Candida albicans
Authors: Neuhäuser Benjamin , Dunkel Nico , Satheesh Somisetty V. , Morschhäuser Joachim
Published: January 2011

The ammonium permease Mep2 induces a switch from unicellular yeast to filamentous growth in response to nitrogen limitation in
Saccharomyces cerevisiae
and
Candida albicans
. In
S. cerevisiae
, the function of Mep2 and other ammonium permeases depends on the protein kinase Npr1. Mutants lacking
NPR1
cannot grow on low concentrations of ammonium and do not filament under limiting nitrogen conditions. A G349C mutation in Mep2 renders the protein independent of Npr1 and results in increased ammonium transport and hyperfilamentous growth, suggesting that the signaling activity of Mep2 directly correlates with its ammonium transport activity. In this study, we investigated the role of Npr1 in ammonium transport and Mep2-mediated filamentation in
C. albicans
. We found that the two ammonium permeases Mep1 and Mep2 of
C. albicans
differ in their dependency on Npr1. While Mep1 could function well in the absence of the Npr1 kinase, ammonium transport by Mep2 was virtually abolished in
npr1
Δ mutants. However, the dependence of Mep2 activity on Npr1 was relieved at higher temperatures (37°C), and Mep2 could efficiently induce filamentous growth under limiting nitrogen conditions in
npr1
Δ mutants. Like in
S. cerevisiae
, mutation of the conserved glycine at position 343 in Mep2 of
C. albicans
to cysteine resulted in Npr1-independent ammonium uptake. In striking contrast, however, the mutation abolished the ability of Mep2 to induce filamentous growth both in the wild type and in
npr1
Δ mutants. Therefore, a mutation that improves ammonium transport by Mep2 under nonpermissible conditions eliminates its signaling activity in
C. albicans
.
Regulatable Ras Activity Is Critical for Proper Establishment and Maintenance of Polarity in Aspergillus fumigatus
Authors: Fortwendel Jarrod R. , Juvvadi Praveen R. , Rogg Luise E. , Steinbach William J.
Published: January 2011

Here we show that expression of a constitutively activated RasA allele, as the sole source of Ras activity, revealed novel Ras-induced phenotypes, including excessive vacuolar expansion and spontaneous lysis of hyphal compartments. These findings highlight the requirement for balanced Ras activity in the establishment and maintenance of polarized growth in filamentous fungi.
Complete Genome Sequence of the Veterinary Pathogen
Staphylococcus pseudintermedius
Strain HKU10-03, Isolated in a Case of Canine Pyoderma
Authors: Tse Herman , Tsoi Hoi Wah , Leung Sze Pui , Urquhart Ian James , Lau Susanna K. P. , Woo Patrick C. Y. , Yuen Kwok Yung
Published: January 2011

Staphylococcus pseudintermedius
is a member of the coagulase-positive staphylococci and is the commonest cause of canine pyoderma. We report the first genome sequence of
S. pseudintermedius
, which shows the presence of numerous virulence factors akin to those of the related human pathogen
Staphylococcus aureus
.
Characterization and Acceptor Preference of a Soluble Meningococcal Group C Polysialyltransferase
Authors: Peterson Dwight C. , Arakere Gayathri , Vionnet Justine , McCarthy Pumtiwitt C. , Vann Willie F.
Published: January 2011

Vaccines against
Neisseria meningitidis
group C are based on its α-2,9-linked polysialic acid capsular polysaccharide. This polysialic acid expressed on the surface of
N. meningitidis
and in the absence of specific antibody serves to evade host defense mechanisms. The polysialyltransferase (PST) that forms the group C polysialic acid (NmC PST) is located in the cytoplasmic membrane. Until recently, detailed characterization of bacterial polysialyltransferases has been hampered by a lack of availability of soluble enzyme preparations. We have constructed chimeras of the group C polysialyltransferase that catalyzes the formation α-2,9-polysialic acid as a soluble enzyme. We used site-directed mutagenesis to determine the region of the enzyme necessary for synthesis of the α-2,9 linkage. A chimera of NmB and NmC PSTs containing only amino acids 1 to 107 of the NmB polysialyltransferase catalyzed the synthesis of α-2,8-polysialic acid. The NmC polysialyltransferase requires an exogenous acceptor for catalytic activity. While it requires a minimum of a disialylated oligosaccharide to catalyze transfer, it can form high-molecular-weight α-2,9-polysialic acid in a nonprocessive fashion when initiated with an α-2,8-polysialic acid acceptor.
De novo
synthesis
in vivo
requires an endogenous acceptor. We attempted to reconstitute
de novo
activity of the soluble group C polysialyltransferase with membrane components. We found that an acapsular mutant with a defect in the polysialyltransferase produces outer membrane vesicles containing an acceptor for the α-2,9-polysialyltransferase. This acceptor is an amphipathic molecule and can be elongated to produce polysialic acid that is reactive with group C-specific antibody.
The Main Virulence Determinant of Yersinia entomophaga MH96 Is a Broad-Host-Range Toxin Complex Active against Insects
Authors: Hurst Mark R. H. , Jones Sandra A. , Binglin Tan , Harper Lincoln A. , Jackson Trevor A. , Glare Travis R.
Published: January 2011

Through transposon mutagenesis and DNA sequence analysis, the main disease determinant of the entomopathogenic bacterium
Yersinia entomophaga
MH96 was localized to an ∼32-kb pathogenicity island (PAI) designated PAI
Ye96
. Residing within PAI
Ye96
are seven open reading frames that encode an insecticidal toxin complex (TC), comprising not only the readily recognized toxin complex A (TCA), TCB, and TCC components but also two chitinase proteins that form a composite TC molecule. The central TC gene-associated region (∼19 kb) of PAI
Ye96
was deleted from the
Y. entomophaga
MH96 genome, and a subsequent bioassay of the ΔTC derivative toward
Costelytra zealandica
larvae showed it to be innocuous. Virulence of the ΔTC mutant strain could be restored by the introduction of a clone containing the entire PAI
Ye96
TC gene region. As much as 0.5 mg of the TC is released per 100 ml of Luria-Bertani broth at 25°C, while at 30 or 37°C, no TC could be detected in the culture supernatant. Filter-sterilized culture supernatants derived from
Y. entomophaga
MH96, but not from the ΔTC strain grown at temperatures of 25°C or less, were able to cause mortality. The 50% lethal doses (LD
50
s) of the TC toward diamondback moth
Plutella xylostella
and
C. zealandica
larvae were defined as 30 ng and 50 ng, respectively, at 5 days after ingestion. Histological analysis of the effect of the TC toward
P. xylostella
larva showed that within 48 h after ingestion of the TC, there was a general dissolution of the larval midgut.
EsaD, a Secretion Factor for the Ess Pathway inStaphylococcus aureus
Authors: Anderson Mark , Chen Yi-Hsing , Butler Emily K. , Missiakas Dominique M.
Published: January 2011

Staphylococcus aureusencodes the Sec-independent Ess secretion pathway, an ortholog of mycobacterial T7 secretion systems which is required for the virulence of this Gram-positive microbe. The Ess (ESXsecretion) pathway was previously defined as a genomic cluster of eight genes,esxA,esaA,essA,essB,esaB,essC,esaC, andesxB. essABCencode membrane proteins involved in the stable expression ofesxA,esxB, andesaC, genes specifying three secreted polypeptide substrates.esaB, which encodes a small cytoplasmic protein, represses the synthesis of EsaC but not that of EsxA and EsxB. Here we investigated a hitherto uncharacterized gene,esaD, located downstream ofesxB. Expression ofesaDis activated by mutations inesaBandessB. EsaD, the 617-amino-acid product ofesaD, is positioned in the membrane and is also accessible to EsaD-specific antibodies on the bacterial surface.S. aureusmutants lackingesaDare defective in the secretion of EsxA. Following intravenous inoculation of mice,S. aureus esaDmutants generate fewer abscesses with a reduced bacterial load compared to wild-type parent strain Newman. The chromosomes ofListeriaandBacillusspecies with Ess pathways also harboresaDhomologues downstream ofesxB, suggesting that the contributory role of EsaD in Ess secretion may be shared among Gram-positive pathogens.
The Three-Layered DNA Uptake Machinery at the Cell Pole in Competent
Bacillus subtilis
Cells Is a Stable Complex
Authors: Kaufenstein Miriam , van der Laan Martin , Graumann Peter L.
Published: January 2011

Many bacteria possess the ability to actively take up DNA from the environment and incorporate it into the chromosome. RecA protein is the key protein achieving homologous recombination. Several of the proteins involved in the transport of DNA across the cell envelope assemble at a single or both cell poles in competent
Bacillus subtilis
cells. We show that the presumed structure that transports DNA across the cell wall, the pseudopilus, also assembles at a single or both cell poles, while the membrane receptor, ComEA, forms a mobile layer throughout the cell membrane. All other known Com proteins, including the membrane permease, localize again to the cell pole, revealing that the uptake machinery has three distinct layers. In cells having two uptake machineries, one complex is occasionally mobile, with pairs of proteins moving together, suggesting that a complete complex may lose anchoring and become mobile. Overall, the cell pole provides stable anchoring. Only one of two uptake machineries assembles RecA protein, suggesting that only one is competent for DNA transfer. FRAP (fluorescence recovery after photobleaching) analyses show that in contrast to known multiprotein complexes, the DNA uptake machinery forms a highly stable complex, showing little or no exchange with unbound molecules. When cells are converted into round spheroplasts, the structure persists, revealing that the assembly is highly stable and does not require the cell pole for its maintenance. High stability may be important to fulfill the mechanical function in pulling DNA across two cell layers.
Autogenous Transcriptional Regulation of the
regA
Gene, Encoding an AraC-Like, Essential Virulence Regulator in
Citrobacter rodentium
Authors: Tan Aimee , Yang Ji , Tauschek Marija , Praszkier Judyta , Robins-Browne Roy M.
Published: January 2011

We identified several promoters responsible for the expression of
regA
, which encodes a global virulence regulator in
Citrobacter rodentium
. Expression of some of the promoters was strongly autoactivated by RegA in conjunction with bicarbonate. Biochemical and mutational analyses were used to determine the consensus sequence of the RegA-binding sites.
Retrospective Application of Transposon-Directed Insertion Site Sequencing to a Library of Signature-Tagged Mini-Tn
5
Km2 Mutants of
Escherichia coli
O157:H7 Screened in Cattle
Authors: Eckert Sabine E. , Dziva Francis , Chaudhuri Roy R. , Langridge Gemma C. , Turner Daniel J. , Pickard Derek J. , Maskell Duncan J. , Thomson Nicholas R. , Stevens Mark P.
Published: January 2011

Massively parallel sequencing of transposon-flanking regions assigned the genotype and fitness score to 91% of
Escherichia coli
O157:H7 mutants previously screened in cattle by signature-tagged mutagenesis (STM). The method obviates the limitations of STM and markedly extended the functional annotation of the prototype
E. coli
O157:H7 genome without further animal use.
A Major Role for Nonenzymatic Antioxidant Processes in the Radioresistance ofHalobacterium salinarum
Authors: Robinson Courtney K. , Webb Kim , Kaur Amardeep , Jaruga Pawel , Dizdaroglu Miral , Baliga Nitin S. , Place Allen , DiRuggiero Jocelyne
Published: January 2011

Oxidative stress occurs when the generation of reactive oxygen species (ROS) exceeds the capacity of the cell's endogenous systems to neutralize them. Our analyses of the cellular damage and oxidative stress responses of the archaeonHalobacterium salinarumexposed to ionizing radiation (IR) revealed a critical role played by nonenzymatic antioxidant processes in the resistance ofH. salinarumto IR. ROS-scavenging enzymes were essential for resistance to chemical oxidants, yet those enzymes were not necessary forH. salinarum's resistance to IR. We found that protein-free cell extracts fromH. salinarumprovided a high level of protection for protein activity against IRin vitrobut did not protect DNA significantly. Compared with cell extracts of radiation-sensitive bacteria,H. salinarumextracts were enriched in manganese, amino acids, and peptides, supporting an essential role in ROS scavenging for those small moleculesin vivo. With regard to chemical oxidants, we showed that the damage caused by gamma irradiation was mechanistically different than that produced by hydrogen peroxide or by the superoxide-generating redox-cycling drug paraquat. The data presented support the idea that IR resistance is most likely achieved by a “metabolic route,” with a combination of tightly coordinated physiological processes.
The Second RNA Chaperone, Hfq2, Is Also Required for Survival under Stress and Full Virulence of
Burkholderia cenocepacia
J2315
Authors: Ramos Christian G. , Sousa Sílvia A. , Grilo André M. , Feliciano Joana R. , Leitão Jorge H.
Published: January 2011

Burkholderia cenocepacia
J2315 is a highly virulent and epidemic clinical isolate of the
B
.
cepacia
complex (Bcc), a group of bacteria that have emerged as important pathogens to cystic fibrosis patients. This bacterium, together with all Bcc strains and a few other prokaryotes, is unusual for encoding in its genome two distinct and functional Hfq-like proteins. In this work, we show results indicating that the 188-amino-acid Hfq2 protein is required for the full virulence and stress resistance of
B
.
cenocepacia
J2315, despite the presence on its genome of the functional 79-amino-acid Hfq protein encoded by the
hfq
gene. Similar to other Hfq proteins, Hfq2 is able to bind RNA. However, Hfq2 is unique in its ability to apparently form trimers
in vitro
. Maximal transcription of
hfq
was observed in
B
.
cenocepacia
J2315 cells in the early exponential phase of growth. In contrast,
hfq2
transcription reached maximal levels in cells in the stationary phase, depending on the CepR quorum-sensing regulator. These results suggest that tight regulation of the expression of these two RNA chaperones is required to maximize the fitness and virulence of this bacterium. In addition, the ability of Hfq2 to bind DNA, not observed for Hfq, suggests that Hfq2 might play additional roles besides acting as an RNA chaperone.