bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro and In Vivo Invasiveness of Different Pulsed-Field Gel Electrophoresis Types of
Listeria monocytogenes
Authors: Larsen Charlotte Nexmann , Nørrung Birgit , Sommer Helle Mølgaard , Jakobsen Mogens 
Published: April 2009

ABSTRACT

The virulence of different pulsed-field gel electrophoresis (PFGE) types of
Listeria monocytogenes
was examined by monitoring their ability to invade Caco-2 cells. Strains belonging to seven different PFGE types originating from both foods and humans were included. No significant differences in invasiveness were detected between strains isolated from humans and those isolated from food. Strains belonging to PFGE type 1 expressed a significantly lower ability to invade cells compared to strains belonging to other PFGE types. Although strains of PFGE type 2 also seemed to invade at a low level, this was not significant in the present study. PFGE types 1 and 2 as well as type 14 are more frequently found in food than the four other PFGE types examined and moreover have a relatively low prevalence in humans compared to their prevalence in food. Thus, the hypothesis that some PFGE types are less virulent than others is supported by this study showing that certain PFGE types of
L. monocytogenes
commonly found in food are less invasive than others to Caco-2 cells. In contrast to the differences in invasion, identical intracellular growth rates between the different PFGE types were observed. In vivo studies of the actual ability of the strains to invade the liver and spleen of cimetidine-treated rats following an oral dose of 10
9
L. monocytogenes
cells were performed for isolates of PFGE types 1, 2, 5, and 15. After 2 days, equal amounts of bacteria were observed in the liver and spleen of the rats for any of the PFGE types tested.
Altered Glycosylation of 63- and 68-Kilodalton Microvillar Proteins in
Heliothis virescens
Correlates with Reduced Cry1 Toxin Binding, Decreased Pore Formation, and Increased Resistance to
Bacillus thuringiensis
Cry1 Toxins
Authors: Jurat-Fuentes Juan Luis , Gould Fred L. , Adang Michael J. 
Published: April 2009

ABSTRACT

The binding and pore formation abilities of Cry1A and Cry1Fa
Bacillus thuringiensis
toxins were analyzed by using brush border membrane vesicles (BBMV) prepared from sensitive (YDK) and resistant (YHD2) strains of
Heliothis virescens
.
125
I-labeled Cry1Aa, Cry1Ab, and Cry1Ac toxins did not bind to BBMV from the resistant YHD2 strain, while specific binding to sensitive YDK vesicles was observed. Binding assays revealed a reduction in Cry1Fa binding to BBMV from resistant larvae compared to Cry1Fa binding to BBMV from sensitive larvae. In agreement with this reduction in binding, neither Cry1A nor Cry1Fa toxin altered the permeability of membrane vesicles from resistant larvae, as measured by a light-scattering assay. Ligand blotting experiments performed with BBMV and
125
I-Cry1Ac did not differentiate sensitive larvae from resistant larvae. Iodination of BBMV surface proteins suggested that putative toxin-binding proteins were exposed on the surface of the BBMV from resistant insects. BBMV protein blots probed with the
N
-acetylgalactosamine-specific lectin soybean agglutinin (SBA) revealed altered glycosylation of 63- and 68-kDa glycoproteins but not altered glycosylation of known Cry1 toxin-binding proteins in YHD2 BBMV. The F1 progeny of crosses between sensitive and resistant insects were similar to the sensitive strain when they were tested by toxin-binding assays, light-scattering assays, and lectin blotting with SBA. These results are evidence that a dramatic reduction in toxin binding is responsible for the increased resistance and cross-resistance to Cry1 toxins observed in the YHD2 strain of
H. virescens
and that this trait correlates with altered glycosylation of specific brush border membrane glycoproteins.
Identification of DNA-Synthesizing Bacterial Cells in Coastal North Sea Plankton
Authors: Pernthaler Annelie , Pernthaler Jakob , Schattenhofer Martha , Amann Rudolf 
Published: April 2009

ABSTRACT

We describe a method for microscopic identification of DNA-synthesizing cells in bacterioplankton samples. After incubation with the halogenated thymidine analogue bromodeoxyuridine (BrdU), environmental bacteria were identified by fluorescence in situ hybridization (FISH) with horseradish peroxidase (HRP)-linked oligonucleotide probes. Tyramide signal amplification was used to preserve the FISH staining during the subsequent immunocytochemical detection of BrdU incorporation. DNA-synthesizing cells were visualized by means of an HRP-labeled antibody Fab fragment and a second tyramide signal amplification step. We applied our protocol to samples of prefiltered (pore size, 1.2 μm) North Sea surface water collected during early autumn. After 4 h of incubation, BrdU incorporation was detected in 3% of all bacterial cells. Within 20 h the detectable DNA-synthesizing fraction increased to >14%. During this period, the cell numbers of members of the
Roseobacter
lineage remained constant, but the fraction of BrdU-incorporating
Roseobacter
sp. cells doubled, from 24 to 42%. In
Alteromonas
sp. high BrdU labeling rates after 4 to 8 h were followed by a 10-fold increase in abundance. Rapid BrdU incorporation was also observed in members of the SAR86 lineage. After 4 h of incubation, cells affiliated with this clade constituted 8% of the total bacteria but almost 50% of the visibly DNA-synthesizing bacterial fraction. Thus, this clade might be an important contributor to total bacterioplankton activity in coastal North Sea water during periods of low phytoplankton primary production. The small size and low ribosome content of SAR86 cells are probably not indications of inactivity or dormancy.
Sensitive In Situ Monitoring of a Recombinant Bioluminescent
Yersinia enterocolitica
Reporter Mutant in Real Time on Camembert Cheese
Authors: Maoz Ariel , Mayr Ralf , Bresolin Geraldine , Neuhaus Klaus , Francis Kevin P. , Scherer Siegfried 
Published: April 2009

ABSTRACT

Bioluminescent mutants of
Yersinia enterocolitica
were generated by transposon mutagenesis using a promoterless, complete
lux
operon (
luxCDABE
) derived from
Photorhabdus luminescens
, and their production of light in the cheese environment was monitored. Mutant B94, which had the
lux
cassette inserted into an open reading frame of unknown function was used for direct monitoring of
Y
.
enterocolitica
cells on cheeses stored at 10°C by quantifying bioluminescence using a photon-counting, intensified charge-coupled device camera. The detection limit on cheese was 200 CFU/cm
2
. Bioluminescence of the reporter mutant was significantly regulated by its environment (NaCl, temperature, and cheese), as well as by growth phase, via the promoter the
lux
operon had acquired upon transposition. At low temperatures, mutant B94 did not exhibit the often-reported decrease of photon emission in older cells. It was not necessary to include either antibiotics or aldehyde in the food matrix in order to gain quantitative, reproducible bioluminescence data. As far as we know, this is the first time a pathogen has been monitored in situ, in real time, in a “real-product” status, and at a low temperature.
Mercury Methylation by
Desulfovibrio desulfuricans
ND132 in the Presence of Polysulfides
Authors: Jay Jenny Ayla , Murray Karen J. , Gilmour Cynthia C. , Mason Robert P. , Morel François M. M. , Roberts A. Lynn , Hemond Harold F. 
Published: April 2009

ABSTRACT

The extracellular speciation of mercury may control bacterial uptake and methylation. Mercury-polysulfide complexes have recently been shown to be prevalent in sulfidic waters containing zero-valent sulfur. Despite substantial increases in total dissolved mercury concentration, methylation rates in cultures of
Desulfovibrio desulfuricans
ND132 equilibrated with cinnabar did not increase in the presence of polysulfides, as expected due to the large size and charged nature of most of the complexes. In natural waters not at saturation with cinnabar, mercury-polysulfide complexes would be expected to shift the speciation of mercury from HgS
0
(aq)
toward charged complexes, thereby decreasing methylation rates.
Large-Scale Production of Coenzyme F
420
-5,6 by Using
Mycobacterium smegmatis
Authors: Isabelle Dale , Simpson D. Randall , Daniels Lacy 
Published: April 2009

ABSTRACT

Production of coenzyme F
420
and its biosynthetic precursor FO was examined with a variety of aerobic actinomycetes to identify an improved source for these materials. Based on fermentation costs, safety, and ease of growth,
Mycobacterium smegmatis
was the best source for F
420
-5,6.
M
.
smegmatis
produced 1 to 3 μmol of intracellular F
420
per liter of culture, which was more than the 0.85 to 1.0 μmol of F
420
-2 per liter usually obtained with
Methanobacterium thermoautotrophicum
and ∼10-fold higher than what was previously reported for the best aerobic actinomycetes. An improved chromatography system using rapidly flowing quaternary aminoethyl ion-exchange material and Florisil was used to more quickly and easily purify F
420
than with previous methods.
Transcript Analysis of Genes Encoding a Family 61 Endoglucanase and a Putative Membrane-Anchored Family 9 Glycosyl Hydrolase from
Phanerochaete chrysosporium
Authors: Wymelenberg Amber Vanden , Denman Stuart , Dietrich Diane , Bassett Jennifer , Yu Xiaochun , Atalla Rajai , Predki Paul , Rudsander Ulla , Teeri Tuula T. , Cullen Daniel 
Published: April 2009

ABSTRACT

Phanerochaete chrysosporium
cellulase genes were cloned and characterized. The
cel61A
product was structurally similar to fungal endoglucanases of glycoside hydrolase family 61, whereas the
cel9A
product revealed similarities to
Thermobifida fusca
Cel9A (E4), an enzyme with both endo- and exocellulase characteristics. The fungal Cel9A is apparently a membrane-bound protein, which is very unusual for microbial cellulases. Transcript levels of both genes were substantially higher in cellulose-grown cultures than in glucose-grown cultures. These results show that
P. chrysosporium
possesses a wide array of conventional and unconventional cellulase genes.
High-Frequency Rugose Exopolysaccharide Production by
Vibrio cholerae
Authors: Ali Afsar , Rashid Mohammed H. , Karaolis David K. R. 
Published: April 2009

ABSTRACT

Vibrio cholerae
can shift to a “rugose” phenotype, thereby producing copious exopolysaccharide (EPS), which promotes its environmental survival and persistence. We report conditions that promote high-frequency rugose EPS production (HFRP), whereby cells switch at high frequency (up to 80%) to rugose EPS production. HFRP appeared to be more common in clinical strains, as HFRP was found in 6 of 19 clinical strains (32%) (including classical, El Tor, and non-O1 strains) but in only 1 of 16 environmental strains (6%). Differences were found between strains in rugose colony morphology, conditions promoting HFRP, the frequency of rugose-to-smooth (R-S) cell reversion, and biofilm formation. We propose that rugose EPS and HFRP provide an evolutionary and adaptive advantage to specific epidemic
V. cholerae
strains for increased persistence in the environment.
Application of Carbon Source Utilization Patterns To Measure the Metabolic Similarity of Complex Dental Plaque Biofilm Microcosms
Authors: Anderson Sally A. , Sissons Christopher H. , Coleman Megan J. , Wong Lisa 
Published: April 2009

ABSTRACT

Biolog technology was applied to measure the metabolic similarity of plaque biofilm microcosms, which model the complex properties of dental plaque in vivo. The choice of Biolog plate, incubation time, and incubation conditions strongly influenced utilization profiles. For plaque biofilm microcosms, Biolog GP2 plates incubated anaerobically in an H
2
-free atmosphere gave the clearest profile. To test the application of the Biolog GP2 assay, plaque microcosms were developed under different nutrient conditions in which the frequency of sucrose application was varied. Cluster analysis of Biolog GP2 data from 10 microcosm biofilms correlated with sucrose frequency. Aciduric bacteria (
Streptococcus mutans
plus lactobacilli) predominated in the plaques receiving high-frequency sucrose applications. Agreement between the Biolog GP2 groupings with nutrient and compositional changes suggests that Biolog analysis is a valuable technique for analyzing the metabolic similarity of dental plaque biofilm microcosms and other high-nutrient or predominantly anaerobic ecosystems.
Serum as a Factor Influencing Adhesion ofEnterococcus faecalisto Glass and Silicone
Authors: Gallardo-Moreno Amparo M. , González-Martín M. Luisa , Pérez-Giraldo Ciro , Bruque José M. , Gómez-García Antonio C. 
Published: April 2009

ABSTRACTThe purpose of this work was to analyze the effect of serum on the physicochemical surface properties and adhesion to glass and silicone ofEnterococcus faecalisATCC 29212 at 37°C. As is presented using thermodynamics analysis, serum minimizes the interaction of cells with water, which correlates well with the increase in hydrophobicity and in bacterial adhesion to glass and silicone.
Influence of Environmental Conditions on Methanogenic Compositions in Anaerobic Biogas Reactors
Authors: Karakashev Dimitar , Batstone Damien J. , Angelidaki Irini 
Published: April 2009

ABSTRACT

The influence of environmental parameters on the diversity of methanogenic communities in 15 full-scale biogas plants operating under different conditions with either manure or sludge as feedstock was studied. Fluorescence in situ hybridization was used to identify dominant methanogenic members of the
Archaea
in the reactor samples; enriched and pure cultures were used to support the in situ identification. Dominance could be identified by a positive response by more than 90% of the total members of the
Archaea
to a specific group- or order-level probe. There was a clear dichotomy between the manure digesters and the sludge digesters. The manure digesters contained high levels of ammonia and of volatile fatty acids (VFA) and were dominated by members of the
Methanosarcinaceae
, while the sludge digesters contained low levels of ammonia and of VFA and were dominated by members of the
Methanosaetaceae
. The methanogenic diversity was greater in reactors operating under mesophilic temperatures. The impact of the original inoculum used for the reactor start-up was also investigated by assessment of the present population in the reactor. The inoculum population appeared to have no influence on the eventual population.
CONTACT STRUCTURES, σ-CONFOLIATIONS AND CONTAMINATIONS IN 3-MANIFOLDS
Authors: OERTEL ULRICH , ŚWIATKOWSKI JACEK 
Published: April 2009

We propose in this paper a method for studying contact structures in 3-manifolds by means of branched surfaces. We explain what it means for a contact structure to be carried by a branched surface embedded in a 3-manifold. To make the transition from contact structures to branched surfaces, we first define auxiliary objects called σ-confoliations and pure contaminations, both generalizing contact structures. We study various deformations of these objects and show that the σ-confoliations and pure contaminations obtained by suitably modifying a contact structure remember the contact structure up to isotopy. After defining tightness for all pure contaminations in a natural way, generalizing the definition of tightness for contact structures, we obtain some conditions on (the embedding of) a branched surface in a 3-manifold sufficient to guarantee that any pure contamination carried by the branched surface is tight. We also find conditions sufficient to prove that a branched surface carries only overtwisted (non-tight) contact structures. Our long-term goal in developing these methods is twofold: Not only do we want to study tight contact structures and pure contaminations, but we also wish to use them as tools for studying 3-manifold topology.
A Tumor-Protective Role for Human Kallikrein-Related Peptidase 6 in Breast Cancer Mediated by Inhibition of Epithelial-to-Mesenchymal Transition
Authors: Pampalakis Georgios , Prosnikli Evangelia , Agalioti Theodora , Vlahou Antonia , Zoumpourlis Vassilis , Sotiropoulou Georgia 
Published: April 2009

Abstract
Human kallikrein-related peptidase 6 (KLK6) was cloned as a putative class II tumor suppressor based on its inactivated expression in metastatic breast cancer. Here, we investigated the mechanism(s) underlying the silencing of KLK6 gene in metastatic breast cancer and its putative implications for tumor progression. We present evidence that tumor-specific loss of KLK6 expression is due to hypermethylation of specific CpGs located in the KLK6 proximal promoter. Methylation-dependent binding of methyl CpG-binding protein 2 and the formation of repressive chromatin mediated by localized histone deacetylation are critical components of KLK6 silencing in breast tumors. Re-expression of KLK6 in nonexpressing MDA-MB-231 breast tumor cells by stable cDNA transfection resulted in marked reversal of their malignant phenotype, manifested by lower proliferation rates and saturation density, marked inhibition of anchorage-independent growth, reduced cell motility, and their dramatically reduced ability to form tumors when implanted in severe combined immunodeficiency mice. Interestingly, inhibition of tumor growth was observed at physiologic concentrations of KLK6, but not when KLK6 was highly overexpressed, as observed in a subset of breast tumors. Differential proteomic profiling revealed that KLK6 re-expression results in significant down-regulation of vimentin which represents an established marker of epithelial-to-mesenchymal transition of tumor cells and in concomitant up-regulation of calreticulin and epithelial markers cytokeratin 8 and 19, indicating that KLK6 may play a protective role against tumor progression that is likely mediated by inhibition of epithelial-to-mesenchymal transition. We suggest that KLK6 is an epigenetically regulated tumor suppressor in human breast cancer and provide ways of pharmacologic modulation. [Cancer Res 2009;69(9):3779–87]
Doxorubicin and Paclitaxel-Loaded Lipid-Based Nanoparticles Overcome Multidrug Resistance by Inhibiting P-Glycoprotein and Depleting ATP
Authors: Dong Xiaowei , Mattingly Cynthia A. , Tseng Michael T. , Cho Moo J. , Liu Yang , Adams Val R. , Mumper Russell J. 
Published: April 2009

AbstractTo test the ability of nanoparticle formulations to overcome P-glycoprotein (P-gp)–mediated multidrug resistance, several different doxorubicin and paclitaxel-loaded lipid nanoparticles were prepared. Doxorubicin nanoparticles showed 6- to 8-fold lower IC50 values in P-gp–overexpressing human cancer cells than those of free doxorubicin. The IC50 value of paclitaxel nanoparticles was over 9-fold lower than that of Taxol in P-gp–overexpressing cells. A series of in vitro cell assays were used including quantitative studies on uptake and efflux, inhibition of calcein acetoxymethylester efflux, alteration of ATP levels, membrane integrity, mitochondrial membrane potential, apoptosis, and cytotoxicity. Enhanced uptake and prolonged retention of doxorubicin were observed with nanoparticle-based formulations in P-gp–overexpressing cells. Calcein acetoxymethylester and ATP assays confirmed that blank nanoparticles inhibited P-gp and transiently depleted ATP. I.v. injection of pegylated paclitaxel nanoparticles showed marked anticancer efficacy in nude mice bearing resistant NCI/ADR-RES tumors versus all control groups. Nanoparticles may be used to target both drug and biological mechanisms to overcome multidrug resistance via P-gp inhibition and ATP depletion. [Cancer Res 2009;69(9):3918–26]
Antitumor Activity of γδ T Cells Reactive against Cytomegalovirus-Infected Cells in a Mouse Xenograft Tumor Model
Authors: Devaud Christel , Bilhere Eric , Loizon Séverine , Pitard Vincent , Behr Charlotte , Moreau Jean-François , Dechanet-Merville Julie , Capone Myriam 
Published: April 2009

Abstractγδ T cells recognize stress-induced autoantigens and contribute to immunity against infections and cancer. Our previous study revealed that Vδ2-negative (neg) γδ T lymphocytes isolated from transplant recipients infected by cytomegalovirus (CMV) killed both CMV-infected cells and HT29 colon cancer cells in vitro. To investigate the antitumor effects of Vδ2neg clones in vivo, we generated hypodermal HT29 tumors in immunodeficient mice. Concomitant injections of Vδ2negclones, in contrast to Vδ2+ cells, prevented the development of HT29 tumors. Vδ2neg clones expressed chemokine C-C motif receptor 3 (CCR3) and migrated in vitro in response to chemokines secreted by HT29 cells, among which were the CCR3 ligands macrophage inflammatory protein-1δ and monocyte chemoattractant protein-4. More importantly, a systemic i.p. treatment with Vδ2neg clones delayed the growth of HT29 s.c. tumors. The effect of in vivo γδ T-cell passive immunotherapy on tumor growth could be reverted by addition of a blocking anti-CCR3 antibody. γδ T-cell passive immunotherapy was dependent on the cytotoxic activity of the γδ effectors toward their targets because Vδ2neg clones were not able to inhibit the growth of A431 hypodermal tumors. Our findings suggest that CMV-specific Vδ2neg cells could target in vivo cancer cells, making them an attractive candidate for antitumor immunotherapy. [Cancer Res 2009;69(9):3971–8]
Neoadjuvant Vaccination Provides Superior Protection against Tumor Relapse following Surgery Compared with Adjuvant Vaccination
Authors: Grinshtein Natalie , Bridle Byram , Wan Yonghong , Bramson Jonathan L. 
Published: April 2009

Abstract
Tumors that recur following surgical resection of melanoma are typically metastatic and associated with poor prognosis. Using the murine B16F10 melanoma and a robust antimelanoma vaccine, we evaluated immunization as a tool to improve tumor-free survival following surgery. We investigated the utility of vaccination in both neoadjuvant and adjuvant settings. Surprisingly, neoadjuvant vaccination was far superior and provided ∼100% protection against tumor relapse. Neoadjuvant vaccination was associated with enhanced frequencies of tumor-specific T cells within the tumor and the tumor-draining lymph nodes following resection. We also observed increased infiltration of antigen-specific T cells into the area of surgery. This method should be amenable to any vaccine platform and can be readily extended to the clinic. [Cancer Res 2009;69(9):3979–85]