bluuebunny/crossref_metadata_2025_split huggingface dataset:
Associations between the Presence of Virulence Determinants and the Epidemiology and Ecology of Zoonotic
Escherichia coli
Authors: O'Reilly K. M. , Low J. C. , Denwood M. J. , Gally D. L. , Evans J. , Gunn G. J. , Mellor D. J. , Reid S. W. J. , Matthews L. 
Published: October 2010

ABSTRACT

The severity of human infection with pathogenic
Escherichia coli
depends on two major virulence determinants (
eae
and
stx
) that, respectively, produce intimin and Shiga toxin. In cattle, both may enhance colonization, but whether this increases fitness by enhancing cattle-to-cattle transmission in the field is unknown. In
E. coli
O157, the almost uniform presence of the virulence determinants in cattle isolates prevents comparative analysis. The availability to this study of extensive non-O157
E. coli
data, with much greater diversity in carriage of virulence determinants, provides the opportunity to gain insight into their potential impact on transmission. Dynamic models were used to simulate expected prevalence distributions for serogroups O26 and O103. Transmission parameters were estimated by fitting model outputs to prevalence data from Scottish cattle using a Bayesian Markov chain Monte Carlo (MCMC) approach. Despite similar prevalence distributions for O26 and O103, their transmission dynamics were distinct. Serogroup O26 strains appear well adapted to the cattle host. The dynamics are characterized by a basic reproduction ratio (
R
0
) of >1 (allowing sustained cattle-to-cattle transmission), a relatively low transmission rate from environmental reservoirs, and substantial association with
eae
on transmission. The presence of
stx
2
was associated with reduced transmission. In contrast, serogroup O103 appears better adapted to the noncattle environment, characterized by an
R
0
value of <1 for plausible test sensitivities, a significantly higher transmission rate from noncattle sources than serogroup O26, and an absence of fitness benefits associated with the carriage of
eae
. Thus, the association of
eae
with enhanced transmission depends on the
E. coli
serogroup. Our results suggest that the capacity of
E. coli
strains to derive fitness benefits from virulence determinants influences the prevalence in the cattle population and the ecology and epidemiology of the host organism.
Antiglycation Effects of Carnosine and Other Compounds on the Long-Term Survival of
Escherichia coli
Authors: Pepper Evan D. , Farrell Michael J. , Nord Gary , Finkel Steven E. 
Published: October 2010

ABSTRACT

Glycation, or nonenzymatic glycosylation, is a chemical reaction between reactive carbonyl-containing compounds and biomolecules containing free amino groups. Carbonyl-containing compounds include reducing sugars such as glucose or fructose, carbohydrate-derived compounds such as methylglyoxal and glyoxal, and nonsugars such as polyunsaturated fatty acids. The latter group includes molecules such as proteins, DNA, and amino lipids. Glycation-induced damage to these biomolecules has been shown to be a contributing factor in human disorders such as Alzheimer's disease, atherosclerosis, and cataracts and in diabetic complications. Glycation also affects
Escherichia coli
under standard laboratory conditions, leading to a decline in bacterial population density and long-term survival. Here we have shown that as
E. coli
aged in batch culture, the amount of carboxymethyl lysine, an advanced glycation end product, accumulated over time and that this accumulation was affected by the addition of glucose to the culture medium. The addition of excess glucose or methylglyoxal to the culture medium resulted in a dose-dependent loss of cell viability. We have also demonstrated that glyoxylase enzyme GloA plays a role in cell survival during glycation stress. In addition, we have provided evidence that carnosine, folic acid, and aminoguanidine inhibit glycation in prokaryotes. These agents may also prove to be beneficial to eukaryotes since the chemical processes of glycation are similar in these two domains of life.
Response of Nursery Pigs to a Synbiotic Preparation of Starch and an Anti-Escherichia coliK88 Probiotic
Authors: Krause D. O. , Bhandari S. K. , House J. D. , Nyachoti C. M. 
Published: October 2010

ABSTRACTPostweaning diarrhea in pigs is frequently caused by enterotoxigenicEscherichia coliK88 (ETEC). The aim of this study was to test the efficacy ofE. coliprobiotics (PRO) in young pigs challenged withE. coliK88. We also tested the synbiotic interaction with raw potato starch (RPS), which can be used as a prebiotic. Forty 17-day-old weaned piglets were randomly assigned to four treatments: treatment 1, positive-control diet (C), no probiotics or RPS but containing in-feed antibiotics; treatment 2, probiotic (PRO), no feed antibiotics plus a 50:50 mixture of probioticE. colistrains UM-2 and UM-7; treatment 3, 14% RPS, no antibiotics (RPS); treatment 4, 14% RPS plus a 50:50 mixture of probioticE. colistrains UM-2 and UM-7, no antibiotics (PRO-RPS). The pigs were challenged with pathogenicE. coliK88 strains on day 7 of the experiment (24-day-old pigs) and euthanized on day 10 of the experiment (35-day-old pigs). Probiotic and pathogenicE. colistrains were enumerated by selective enrichment on antibiotics, and microbial community analysis was conducted using terminal restriction length polymorphism analysis (T-RFLP) of 16S rRNA genes. The combination of raw potato starch and the probiotic had a beneficial effect on piglet growth performance and resulted in a reduction of diarrhea and increased microbial diversity in the gut. We conclude that the use ofE. coliprobiotic strains againstE. coliK88 in the presence of raw potato starch is effective in reducing the negative effects of ETEC in a piglet challenge model.
Construction of a Single-Chain Variable-Fragment Antibody against the Superantigen Staphylococcal Enterotoxin B
Authors: Singh Pawan Kumar , Agrawal Ranu , Kamboj Dev Vrat , Gupta Garima , Boopathi M. , Goel Ajay Kumar , Singh Lokendra 
Published: October 2010

ABSTRACTStaphylococcal food poisoning (SFP) is one of the most prevalent causes of food-borne illness throughout the world. SFP is caused by 21 different types of staphylococcal enterotoxins produced byStaphylococcus aureus. Among these, staphylococcal enterotoxin B (SEB) is the most potent toxin and is a listed biological warfare (BW) agent. Therefore, development of immunological reagents for detection of SEB is of the utmost importance. High-affinity and specific monoclonal antibodies are being used for detection of SEB, but hybridoma clones tend to lose their antibody-secreting ability over time. This problem can be overcome by the use of recombinant antibodies produced in a bacterial system. In the present investigation, genes from a hybridoma clone encoding monoclonal antibody against SEB were immortalized using antibody phage display technology. A murine phage display library containing single-chain variable-fragment (ScFv) antibody genes was constructed in a pCANTAB 5E phagemid vector. Phage particles displaying ScFv were rescued by reinfection of helper phage followed by four rounds of biopanning for selection of SEB binding ScFv antibody fragments by using phage enzyme-linked immunosorbent assay (ELISA). Soluble SEB-ScFv antibodies were characterized from one of the clones showing high affinity for SEB. The anti-SEB ScFv antibody was highly specific, and its affinity constant was 3.16 nM as determined by surface plasmon resonance (SPR). These results demonstrate that the recombinant antibody constructed by immortalizing the antibody genes from a hybridoma clone is useful for immunodetection of SEB.
Antibiotic-Resistant
Escherichia coli
Bacteria, Including Strains with Genes Encoding the Extended-Spectrum Beta-Lactamase and QnrS, in Waterbirds on the Baltic Sea Coast of Poland
Authors: Literak Ivan , Dolejska Monika , Janoszowska Dagmar , Hrusakova Jolana , Meissner Wlodzimierz , Rzyska Hanna , Bzoma Szymon , Cizek Alois 
Published: October 2010

ABSTRACT

Individual cloacal swabs of mallards (
Anas platyrhynchos
) and of herring gulls (
Larus argentatus
), as well as samples of waterbird feces obtained in 2008 and 2009, were cultivated for
Escherichia coli
. Isolates of
E. coli
were tested for susceptibilities to 12 antimicrobial agents by the disk diffusion method. Moreover, the samples were subcultivated on MacConkey agar (MCA) containing cefotaxime (2 mg liter
−1
) to detect
E. coli
with extended-spectrum beta-lactamase (ESBL) and subsequently on MCA supplemented with ciprofloxacin (0.05 mg liter
−1
) and MCA with nalidixic acid (20 mg liter
−1
) to isolate fluoroquinolone-resistant
E. coli
. PCR was used to detect specific antibiotic resistance genes. We found 9
E. coli
isolates producing ESBL with
bla
genes:
bla
CTX-M-1
(6 isolates),
bla
CTX-M-9
plus
bla
TEM-1b
(1 isolate),
bla
CTX-M-15
plus
bla
OXA-1
(1 isolate), and
bla
SHV-12
(1 isolate). In the isolate with
bla
CTX-M-15
, the gene
aac(6)-Ib-cr
was also detected. The
bla
genes were harbored by transferable plasmids of the IncN and IncI1 groups. Nine quinolone-resistant
E. coli
isolates with
qnrS
genes were found and characterized. The gene
qnrS
was associated with a Tn
3
-like transposon on the IncX1 plasmid together with
bla
TEM-1
in two isolates. The gene
qnrS
was also harbored by conjugative plasmids of the IncN and IncX2 groups. Even if populations of wild birds are not directly influenced by antibiotic practice, we have demonstrated that antibiotic-resistant
E. coli
strains, including strains with various ESBL and
qnrS
genes, are found in the feces of wild birds on the coast of the Baltic Sea in Poland.
Accumulation of Non-Superoxide Anion Reactive Oxygen Species Mediates Nitrogen-Limited Alcoholic Fermentation by
Saccharomyces cerevisiae
Authors: Mendes-Ferreira Ana , Sampaio-Marques Belém , Barbosa Catarina , Rodrigues Fernando , Costa Vítor , Mendes-Faia Arlete , Ludovico Paula , Leão Cecília 
Published: October 2010

ABSTRACT

Throughout alcoholic fermentation, nitrogen depletion is one of the most important environmental stresses that can negatively affect the yeast metabolic activity and ultimately leads to fermentation arrest. Thus, the identification of the underlying effects and biomarkers of nitrogen limitation is valuable for controlling, and therefore optimizing, alcoholic fermentation. In this study, reactive oxygen species (ROS), plasma membrane integrity, and cell cycle were evaluated in a wine strain of
Saccharomyces cerevisiae
during alcoholic fermentation in nitrogen-limiting medium under anaerobic conditions. The results indicated that nitrogen limitation leads to an increase in ROS and that the superoxide anion is a minor component of the ROS, but there is increased activity of both Sod2p and Cta1p. Associated with these effects was a decrease in plasma membrane integrity and a persistent cell cycle arrest at G
0
/G
1
phases. Moreover, under these conditions it appears that autophagy, evaluated by
ATG8
expression, is induced, suggesting that this mechanism is essential for cell survival but does not prevent the cell cycle arrest observed in slow fermentation. Conversely, nitrogen refeeding allowed cells to reenter cell cycle by decreasing ROS generation and autophagy. Altogether, the results provide new insights on the understanding of wine fermentations under nitrogen-limiting conditions and further indicate that ROS accumulation, evaluated by the MitoTracker Red dye CM-H
2
XRos, and plasma membrane integrity could be useful as predictive markers of fermentation problems.
Determination of the Effects of Medium Composition on the Monochloramine Disinfection Kinetics of
Nitrosomonas europaea
by the Propidium Monoazide Quantitative PCR and Live/Dead BacLight Methods
Authors: Wahman David G. , Schrantz Karen A. , Pressman Jonathan G. 
Published: October 2010

ABSTRACT

Various medium compositions (phosphate, 1 to 50 mM; ionic strength, 2.8 to 150 meq/liter) significantly affected
Nitrosomonas europaea
monochloramine disinfection kinetics, as determined by the Live/Dead BacLight (LD) and propidium monoazide quantitative PCR (PMA-qPCR) methods (lag coefficient, 37 to 490 [LD] and 91 to 490 [PMA-qPCR] mg·min/liter; Chick-Watson rate constant, 4.0 × 10
−3
to 9.3 × 10
−3
[LD] and 1.6 × 10
−3
to 9.6 × 10
−3
[PMA-qPCR] liter/mg·min). Two competing effects may account for the variation in disinfection kinetic parameters: (i) increasing kinetics (disinfection rate constant [
k
] increased, lag coefficient [
b
] decreased) with increasing phosphate concentration and (ii) decreasing kinetics (
k
decreased,
b
increased) with increasing ionic strength. The results support development of a standard medium for evaluating disinfection kinetics in drinking water.
Characterization of the Protocatechuate 4,5-Cleavage Pathway Operon in
Comamonas
sp. Strain E6 and Discovery of a Novel Pathway Gene
Authors: Kamimura Naofumi , Aoyama Taichi , Yoshida Rieko , Takahashi Kenji , Kasai Daisuke , Abe Tomokuni , Mase Kohei , Katayama Yoshihiro , Fukuda Masao , Masai Eiji 
Published: October 2010

ABSTRACT

The protocatechuate (PCA) 4,5-cleavage (PCA45) pathway is the essential catabolic route for the degradation of various aromatic acids in the genus
Comamonas
. All of the PCA45 pathway genes,
orf1-pmdKEFDABC
, as well as another PCA 4,5-dioxygenase gene,
pmdA
II
B
II
, were isolated from a phthalate-degrading bacterium,
Comamonas
sp. strain E6. Disruption of
pmdB
and
pmdD
in E6, which code for the β subunit of PCA 4,5-dioxygenase and 2-pyrone-4,6-dicarboxylate (PDC) hydrolase, respectively, resulted in a growth defect on PCA, indicating that these genes are essential for the growth of E6 on PCA. On the other hand, inactivation of
pmdB
II
did not affect the growth of E6 on PCA. Disruption of
pmdK
, which is related to a 4-hydroxybenzoate/PCA transporter of
Pseudomonas putida
, resulted in growth retardation on PCA. The insertional inactivation of
orf1
in E6, whose deduced amino acid sequence has no similarity with proteins of known function, led to the complete loss of growth on PCA and the accumulation of PDC and 4-oxalomesaconate (OMA) from PCA. These results indicated the involvement of
orf1
in the PCA45 pathway, and this gene, designated
pmdU
, was suggested to code for OMA tautomerase. Reverse transcription-PCR analysis suggested that the
pmdUKEFDABC
genes constitute an operon. The transcription start site of the
pmd
operon was mapped at 167 nucleotides upstream of the initiation codon of
pmdU
. The
pmd
promoter activity was enhanced 20-fold when the cells were grown in the presence of PCA. Inducers of the
pmd
operon were found to be PCA and PDC, but PDC was the more effective inducer.
Does Aqueous Fullerene Inhibit the Growth of
Saccharomyces cerevisiae
or
Escherichia coli
?
Authors: Hadduck Alex N. , Hindagolla Vihangi , Contreras Alison E. , Li Qilin , Bakalinsky Alan T. 
Published: October 2010

ABSTRACT

Studies reporting on potentially toxic interactions between aqueous fullerene nanoparticles (nC
60
) and microorganisms have been contradictory. When known confounding factors were avoided, growth yields of
Saccharomyces cerevisiae
and
Escherichia coli
cultured in the presence and absence of independently prepared lots of underivatized nC
60
were found not to be significantly different.
Hal4 and Hal5 Protein Kinases Are Required for General Control of Carbon and Nitrogen Uptake and Metabolism
Authors: Pérez-Valle Jorge , Rothe Jessica , Primo Cecilia , Martínez Pastor Mar , Ariño Joaquin , Pascual-Ahuir Amparo , Mulet José Miguel , Serrano Ramón , Yenush Lynne 
Published: October 2010

ABSTRACT

The yeast protein kinases Sat4/Hal4 and Hal5 are required for the plasma membrane stability of the K
+
transporter Trk1 and some amino acid and glucose permeases. The transcriptomic analysis presented here indicates alterations in the general control of the metabolism of both nitrogen and carbon. Accordingly, we observed reduced uptake of methionine and leucine in the
hal4 hal5
mutant. This decrease correlates with activation of the Gcn2-Gcn4 pathway, as measured by expression of the
lacZ
gene under the control of the
GCN4
promoter. However, with the exception of methionine biosynthetic genes, few amino acid biosynthetic genes are induced in the
hal4 hal5
mutant, whereas several genes involved in amino acid catabolism are repressed. Concerning glucose metabolism, we found that this mutant exhibits derepression of respiratory genes in the presence of glucose, leading to an increased activity of mitochondrial enzymes, as measured by succinate dehydrogenase (SDH) activity. In addition, the reduced glucose consumption in the
hal4 hal5
mutant correlates with a more acidic intracellular pH and with low activity of the plasma membrane H
+
-ATPase. As a compensatory mechanism for the low glycolytic rate, the
hal4 hal5
mutant overexpresses the
HXT4
high-affinity glucose transporter and the hexokinase genes. These results indicate that the
hal4 hal5
mutant presents defects in the general control of nitrogen and carbon metabolism, which correlate with reduced transport of amino acids and glucose, respectively. A more acidic intracellular pH may contribute to some defects of this mutant.
A Mutant Defective in Sexual Development Produces Aseptate Ascogonia
Authors: Bloemendal Sandra , Lord Kathryn M. , Rech Christine , Hoff Birgit , Engh Ines , Read Nick D. , Kück Ulrich 
Published: October 2010

ABSTRACT

The transition from the vegetative to the sexual cycle in filamentous ascomycetes is initiated with the formation of ascogonia. Here, we describe a novel type of sterile mutant from
Sordaria macrospora
with a defect in ascogonial septum formation. This mutant, named pro22, produces only small, defective protoperithecia and carries a point mutation in a gene encoding a protein that is highly conserved throughout eukaryotes. Sequence analyses revealed three putative transmembrane domains and a C-terminal domain of unknown function. Live-cell imaging showed that PRO22 is predominantly localized in the dynamic tubular and vesicular vacuolar network of the peripheral colony region close to growing hyphal tips and in ascogonia; it is absent from the large spherical vacuoles in the vegetative hyphae of the subperipheral region of the colony. This points to a specific role of PRO22 in the tubular and vesicular vacuolar network, and the loss of intercalary septation in ascogonia suggests that PRO22 functions during the initiation of sexual development.
Functional Characterization of a New Member of the Cdk9 Family in Aspergillus nidulans
Authors: Bathe Friederike , Kempf Claudia , Osmani Stephen A. , Osmani Aysha H. , Hettinger Sabrina , Wohlmann Elke , Fischer Reinhard 
Published: October 2010

ABSTRACT

Cdk9-like kinases in complex with T-type cyclins are essential components of the eukaryotic transcription elongation machinery. The full spectrum of Cdk9/cyclin T targets, as well as the specific consequences of phosphorylations, is still largely undefined. We identify and characterize here a Cdk9 kinase (PtkA) in the filamentous ascomycete
Aspergillus nidulans
. Deletion of
ptkA
had a lethal effect in later stages of vegetative growth and completely impeded asexual development. Overexpression of
ptkA
affected directionality of polarized growth and the initiation of new branching sites. A green fluorescent protein-tagged PtkA version localized inside the nucleus during interphase, supporting a role of PtkA in transcription elongation, as observed in other organisms. We also identified a putative cyclin T homolog, PchA, in the
A. nidulans
genome and confirmed its interaction with PtkA
in vivo
. Surprisingly, the Pcl-like cyclin PclA, previously described to be involved in asexual development, was also found to interact with PtkA, indicating a possible role of PtkA in linking transcriptional activity with development and/or morphogenesis in
A. nidulans
. This is the first report of a Cdk9 kinase interacting with a Pcl-like cyclin, revealing interesting new aspects about the involvement of this Cdk-subfamily in differential gene expression.
Preclinical Evaluation of the Pht Proteins as Potential Cross-Protective Pneumococcal Vaccine Antigens
Authors: Godfroid Fabrice , Hermand Philippe , Verlant Vincent , Denoël Philippe , Poolman Jan T. 
Published: October 2010

ABSTRACT
Current pneumococcal vaccines are composed of capsular polysaccharides (PS) of various serotypes, either as free PS or as protein-PS conjugates. The use of pneumococcus protein antigens that are able to afford protection across the majority of serotypes is envisaged as a relevant alternative and/or complement to the polysaccharides. In this context, based on several studies, the Pht protein family emerged as relevant vaccine candidates. The purpose of the present study was to evaluate the Pht protein family in several preclinical mouse models. Immunization with these antigens was compared with immunization with other pneumococcal antigens, such as CbpA, PspA, and PsaA. In a nasopharyngeal colonization model and in a lung colonization model, the Phts were found to be superior to the other candidates in terms of efficacy of protection and serotype coverage. Likewise, vaccination with PhtD allowed higher animal survival rates after lethal intranasal challenge. Finally, a passive transfer model in which natural anti-PhtD human antibodies were transferred into mice demonstrated significant protection against lethal intranasal challenge. This indicates that natural anti-PhtD human antibodies are able to protect against pneumococcal infection. Our findings, together with the serotype-independent occurrence of the Phts, designate this protein family as valid candidate antigens to be incorporated in protein-based pneumococcal vaccines.
Nontypeable
Haemophilus influenzae
Initiates Formation of Neutrophil Extracellular Traps
Authors: Juneau Richard A. , Pang Bing , Weimer Kristin E. D. , Armbruster Chelsie E. , Swords W. Edward 
Published: October 2010

ABSTRACT

Nontypeable
Haemophilus influenzae
(NTHI) is a leading cause of otitis media infections, which are often chronic and/or recurrent in nature. NTHI and other bacterial species persist
in vivo
within biofilms during otitis media and other persistent infections. These biofilms have a significant host component that includes neutrophil extracellular traps (NETs). These NETs do not mediate clearance of NTHI, which survives within NET structures by means of specific subpopulations of lipooligosaccharides on the bacterial surface that are determinants of biofilm formation
in vitro
. In this study, the ability of NTHI and NTHI components to initiate NET formation was examined using an
in vitro
model system. Both viable and nonviable NTHI strains were shown to promote NET formation, as did preparations of bacterial DNA, outer membrane proteins, and lipooligosaccharide (endotoxin). However, only endotoxin from a parental strain of NTHI exhibited equivalent potency in NET formation to that of NTHI. Additional studies showed that NTHI entrapped within NET structures is resistant to both extracellular killing within NETs and phagocytic killing by incoming neutrophils, due to oligosaccharide moieties within the lipooligosaccharides. Thus, we concluded that NTHI elicits NET formation by means of multiple pathogen-associated molecular patterns (most notably endotoxin) and is highly resistant to killing within NET structures. These data support the conclusion that, for NTHI, formation of NET structures may be a persistence determinant by providing a niche within the middle-ear chamber.