bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of mitogen‐ and stress‐activated protein kinase 1 and 2 in chronic skin inflammation in mice
Authors: Bertelsen Trine , Iversen Lars , Riis Jette Lindorff , Arthur J. Simon C. , Bibby Bo Martin , Kragballe Knud , Johansen Claus
Published: December 2010

Abstract:  Mitogen‐ and stress‐activated protein kinase 1 and 2 (MSK1/2) are two kinases phosphorylated by both ERK1/2 and p38 MAPK. Recently, MSK1 and 2 have been reported to act as negative regulators of acute inflammation. In this study, we investigated the role of MSK1/2 in chronic skin inflammation using an oxazolone‐induced allergic contact dermatitis model in MSK1/2 knockout mice and wild‐type mice. MSK1/2 knockout mice were demonstrated to have significantly increased inflammation compared with wild‐type mice. This was measured by an increased ear thickness, elevated infiltration of neutrophils in the skin and increased inflammatory histological changes. Furthermore, we found significantly elevated levels of the proinflammatory cytokines Tumor necrosis factor‐α (TNF‐α), IL‐1β and IL‐6 at both mRNA and protein levels in MSK1/2 knockout mice compared with wild‐type mice after oxazolone treatment. In addition, the mRNA expression of the chemokine Thymus and activation regulated chemokine (TARC) was demonstrated to be significantly elevated in oxazolone‐treated MSK1/2 knockout mice compared with wild‐type mice. The increased expression of TARC was paralleled by increased infiltration of cells positive for the TARC receptor, CCR4, in the dermis of MSK1/2 knockout mice. Our results indicate that MSK1/2 are involved in the activation of feedback mechanisms that dampen oxazolone‐induced skin inflammation.
Measuring Platelet Aggregation in Dialysis Patients With a Whole Blood Aggregometer by the Screen Filtration Pressure Method
Authors: Waki Kayo , Hayashi Aki , Ikeda Shigeo , Ikeda Sadao , Nagatsuka Kazuhiro , Honma Yoshiyuki , Kadowaki Takashi , Yoshinoya Sadayoshi
Published: December 2010

A semi‐automatic, whole‐blood aggregometer based on the screen filtration pressure (SFP) method is now widely used clinically and in research, but has not been used with hemodialysis (HD) patients. We measured whole‐blood platelet aggregation in HD patients by the SFP method. This retrospective cross‐sectional study included 62 HD patients, of whom 47 were non‐diabetic and 15 were diabetic; we also included a control group of healthy, non‐uremic subjects. With the t‐test, we examined differences in the platelet aggregation threshold index (PATI) in meaningful sub‐groupings of the HD patients, depending on whether or not they had diabetes, and whether or not they had been given antiplatelet agents. Considering the non‐diabetic HD patients first, their PATI values were significantly higher than those values in the control subjects (3.1 [1.0–5.2] vs. 1.8 [1.3–2.3] µM, P < 0.001). The non‐diabetic HD patients taking antiplatelet agents showed significantly (1.9 times) higher PATI values than the non‐diabetic HD patients without antiplatelet agents (4.4 [1.8–7.0] vs. 2.3 [1.3–3.3] µM, P = 0.003). We observed similar trends among diabetic HD patients. Whole‐blood analysis by the SPF method seems to be a promising way of monitoring platelet function for HD patients.
Variability and Component Criticality in Component Reuse and Remanufacturing Systems
Authors: Pandey Vijitashwa , Thurston Deborah
Published: December 2010

Different operations, such as take-back, cleaning, and repair, lead to high system variability rendering remanufacturing systems difficult to manage. Even when a product is successfully remanufactured, there remains the problem of customer perception of remanufactured products being not able to perform as well as new ones. The possibility of several different options (reusing, remanufacturing, and recycling) further compound the complexity of the information set that should be considered for effective remanufacturing. This paper develops a method that can be employed for making component level decisions that accounts for aforesaid issues. A metric is proposed that measures the randomness or variability imposed by a reuse alternative. A measure of effective age is also proposed, extending the lines of previous research. A washing machine example illustrates the method and how the two measures can be incorporated into a design decision model.
Electromechanical Modeling and Nonlinear Analysis of Axially Loaded Energy Harvesters
Authors: Masana Ravindra , Daqaq Mohammed F.
Published: December 2010

To maximize the electromechanical transduction of vibratory energy harvesters, the resonance frequency of the harvesting device is usually tuned to the excitation frequency. To achieve this goal, some concepts call for utilizing an axial static preload to soften or stiffen the structure (Leland and Wright, 2006, “Resonance Tuning of Piezoelectric Vibration Energy Scavenging Generators Using Compressive Axial Preload,” Smart Mater. Struct., 15, pp. 1413–1420; Morris et al., 2008, “A Resonant Frequency Tunable, Extensional Mode Piezoelectric Vibration Harvesting Mechanism,” Smart Mater. Struct., 17, p. 065021). For the most part, however, models used to describe the effect of the axial preload on the harvester’s response are linear lumped-parameter models that can hide some of the essential features of the dynamics and, sometimes, oppose the experimental trends. To resolve this issue, this study aims to develop a comprehensive understanding of energy harvesting using axially loaded beams. Specifically, using nonlinear Euler–Bernoulli beam theory, an electromechanical model of a clamped-clamped energy harvester subjected to transversal excitations and static axial loading is developed and discretized using a Galerkin expansion. Using the method of multiple scales, the general nonlinear physics of the system is investigated by obtaining analytical expressions for the steady-state response amplitude, the voltage drop across a resistive load, and the output power. These theoretical expressions are then validated against experimental data. It is demonstrated that in addition to the ability of tuning the harvester to the excitation frequency via axial load variations, the axial load aids in (i) increasing the electric damping in the system, thereby enhancing the energy transfer from the beam to the electric load, (ii) amplifying the effect of the external excitation on the structure, and (iii) enhancing the effective nonlinearity of the device. These factors combined can increase the steady-state response amplitude, output power, and bandwidth of the harvester.
Heterologously Expressed Family 51 α-
l
-Arabinofuranosidases from
Oenococcus oeni
and
Lactobacillus brevis
Authors: Michlmayr Herbert , Schümann Christina , Kulbe Klaus D. , del Hierro Andrés M.
Published: December 2010

Putative α-
l
-arabinofuranosidases of
Oenococcus oeni
and
Lactobacillus brevis
were heterologously expressed and characterized. We report the basic functional properties of the recombinant enzymes in comparison to those of a commercial family 51 arabinosidase of
Aspergillus niger.
Developmental Penalties Associated with Inducible Tolerance in
Helicoverpa armigera
to Insecticidal Toxins from
Bacillus thuringiensis
Authors: Rahman Mahbub , Glatz Richard , Roush Rick , Schmidt Otto
Published: December 2010

Exposure of insect larvae to sublethal concentrations of crystal toxins from the soil bacterium
Bacillus thuringiensis
(Bt toxins) causes the induction of immune and metabolic responses that can be transmitted to offspring by epigenetic inheritance mechanisms. Given that the elevated immune status carries significant developmental penalties, we wanted to establish the relationships between immune induction, tolerance to the toxin and developmental penalties. A laboratory culture of
Helicoverpa armigera
was induced by a sublethal bacterial suspension containing crystal toxin Cry1Ac in one generation and maintained in the presence of toxin, acquiring significant levels of tolerance to the toxin within 12 generations of continuous exposure. Comparing tolerant and susceptible insects, we show that the induction of larval immune response and the coincident alteration of development-related metabolic activities by elicitors in the larval gut (larval induction) differs from the elevated immune status transmitted by epigenetic mechanisms (embryonic induction). Because the damaging effects of larval induction processes are higher compared to embryonic induction, it is likely that overall developmental penalties depend on the relative contribution of the two induction processes. When insects are kept with the same amount of toxin in the diet for subsequent generations, the embryonic induction process increases its contribution compared to the larval induction, resulting in reduced overall developmental penalty, while tolerance to the toxin is maintained.
Autophagy Deficiency Promotes β-Lactam Production in
Penicillium chrysogenum
Authors: Bartoszewska Magdalena , Kiel Jan A. K. W. , Bovenberg Roel A. L. , Veenhuis Marten , van der Klei Ida J.
Published: December 2010

We have investigated the significance of autophagy in the production of the β-lactam antibiotic penicillin (PEN) by the filamentous fungus
Penicillium chrysogenum
. In this fungus PEN production is compartmentalized in the cytosol and in peroxisomes. We demonstrate that under PEN-producing conditions significant amounts of cytosolic and peroxisomal proteins are degraded via autophagy. Morphological analysis, based on electron and fluorescence microscopy, revealed that this phenomenon might contribute to progressive deterioration of late subapical cells. We show that deletion of the
P. chrysogenum
ortholog of
Saccharomyces cerevisiae
serine-threonine kinase
atg1
results in impairment of autophagy. In
P. chrysogenum atg1
cells, a distinct delay in cell degeneration is observed relative to wild-type cells. This phenomenon is associated with an increase in the enzyme levels of the PEN biosynthetic pathway and enhanced production levels of this antibacterial compound.
Transcriptional and Proteomic Responses ofPseudomonas aeruginosaPAO1 to Spaceflight Conditions Involve Hfq Regulation and Reveal a Role for Oxygen
Authors: Crabbé Aurélie , Schurr Michael J. , Monsieurs Pieter , Morici Lisa , Schurr Jill , Wilson James W. , Ott C. Mark , Tsaprailis George , Pierson Duane L. , Stefanyshyn-Piper Heidi , Nickerson Cheryl A.
Published: December 2010

Assessing bacterial behavior in microgravity is important for risk assessment and prevention of infectious diseases during spaceflight missions. Furthermore, this research field allows the unveiling of novel connections between low-fluid-shear regions encountered by pathogens during their natural infection process and bacterial virulence. This study is the first to characterize the spaceflight-induced global transcriptional and proteomic responses ofPseudomonas aeruginosa, an opportunistic pathogen that is present in the space habitat.P. aeruginosaresponded to spaceflight conditions through differential regulation of 167 genes and 28 proteins, with Hfq as a global transcriptional regulator. Since Hfq was also differentially regulated in spaceflight-grownSalmonella entericaserovar Typhimurium, Hfq represents the first spaceflight-induced regulator acting across bacterial species. The majorP. aeruginosavirulence-related genes induced in spaceflight were thelecAandlecBlectin genes and the gene for rhamnosyltransferase (rhlA), which is involved in rhamnolipid production. The transcriptional response of spaceflight-grownP. aeruginosawas compared with our previous data for this organism grown in microgravity analogue conditions using the rotating wall vessel (RWV) bioreactor. Interesting similarities were observed, including, among others, similarities with regard to Hfq regulation and oxygen metabolism. While RWV-grownP. aeruginosamainly induced genes involved in microaerophilic metabolism,P. aeruginosacultured in spaceflight presumably adopted an anaerobic mode of growth, in which denitrification was most prominent. Whether the observed changes in pathogenesis-related gene expression in response to spaceflight culture could lead to an alteration of virulence inP. aeruginosaremains to be determined and will be important for infectious disease risk assessment and prevention, both during spaceflight missions and for the general public.
Different Substrate Recognition Requirements for Cleavage of Synaptobrevin-2 byClostridium baratiiandClostridium botulinumType F Neurotoxins
Authors: Kalb Suzanne R. , Baudys Jakub , Egan Christina , Smith Theresa J. , Smith Leonard A. , Pirkle James L. , Barr John R.
Published: December 2010

Botulinum neurotoxins (BoNTs) cause botulism, which can be fatal if it is untreated. BoNTs cleave proteins necessary for nerve transmission, resulting in paralysis. Thein vivoprotein target has been reported for all seven serotypes of BoNT, i.e., serotypes A to G. Knowledge of the cleavage sites has led to the development of several assays to detect BoNT based on its ability to cleave a peptide substrate derived from itsin vivoprotein target. Most serotypes of BoNT can be subdivided into subtypes, and previously, we demonstrated that three of the currently known subtypes of BoNT/F cleave a peptide substrate, a shortened version of synaptobrevin-2, between Q58 and K59. However, our research indicated thatClostridium baratiitype F toxin did not cleave this peptide. In this study, we detail experiments demonstrating thatClostridium baratiitype F toxin cleaves recombinant synaptobrevin-2 in the same location as that cleaved by proteolytic F toxin. In addition, we demonstrate thatClostridium baratiitype F toxin can cleave a peptide substrate based on the sequence of synaptobrevin-2. This peptide substrate is an N-terminal extension of the original peptide substrate used for detection of other BoNT/F toxins and can be used to detect four of the currently known BoNT/F subtypes by mass spectrometry.
Rapid, Semiautomated Quantification of Bacterial Cells in Freshwater by Using a Microfluidic Device for On-Chip Staining and Counting
Authors: Yamaguchi Nobuyasu , Torii Masashi , Uebayashi Yuko , Nasu Masao
Published: December 2010

A microfluidic device-based system for the rapid and semiautomated counting of bacteria in freshwater was fabricated and examined. Bacteria in groundwater and in potable water, as well as starved
Escherichia coli
O157:H7 spiked in pond water, were able to be on-chip stained and enumerated within 1 h using this system.
β-1,3-Glucanase from
Delftia tsuruhatensis
Strain MV01 and Its Potential Application in Vinification
Authors: Blättel V. , Larisika M. , Pfeiffer P. , Nowak C. , Eich A. , Eckelt J. , König H.
Published: December 2010

During vinification microbial activities can spoil wine quality. As the wine-related lactic acid bacterium
Pediococcus parvulus
is able to produce slimes consisting of a β-1,3-glucan, must and wine filtration can be difficult or impossible. In addition, the metabolic activities of several wild-type yeasts can also negatively affect wine quality. Therefore, there is a need for measures to degrade the exopolysaccharide from
Pediococcus parvulus
and to inhibit the growth of certain yeasts. We examined an extracellular β-1,3-glucanase from
Delftia tsuruhatensis
strain MV01 with regard to its ability to hydrolyze both polymers, the β-1,3-glucan from
Pediococcus
and that from yeast cell walls. The 29-kDa glycolytic enzyme was purified to homogeneity. It exhibited an optimal activity at 50°C and pH 4.0. The sequencing of the N terminus revealed significant similarities to β-1,3-glucanases from different bacteria. In addition, the investigations indicated that this hydrolytic enzyme is still active under wine-relevant parameters such as elevated ethanol, sulfite, and phenol concentrations as well as at low pH values. Therefore, the characterized enzyme seems to be a useful tool to prevent slime production and undesirable yeast growth during vinification.
Global Gene Expression Patterns in
Clostridium thermocellum
as Determined by Microarray Analysis of Chemostat Cultures on Cellulose or Cellobiose
Authors: Riederer Allison , Takasuka Taichi E. , Makino Shin-ichi , Stevenson David M. , Bukhman Yury V. , Elsen Nathaniel L. , Fox Brian G.
Published: December 2010

A microarray study of chemostat growth on insoluble cellulose or soluble cellobiose has provided substantial new information on
Clostridium thermocellum
gene expression. This is the first comprehensive examination of gene expression in
C. thermocellum
under defined growth conditions. Expression was detected from 2,846 of 3,189 genes, and regression analysis revealed 348 genes whose changes in expression patterns were growth rate and/or substrate dependent. Successfully modeled genes included those for scaffoldin and cellulosomal enzymes, intracellular metabolic enzymes, transcriptional regulators, sigma factors, signal transducers, transporters, and hypothetical proteins. Unique genes encoding glycolytic pathway and ethanol fermentation enzymes expressed at high levels simultaneously with previously established maximal ethanol production were also identified. Ranking of normalized expression intensities revealed significant changes in transcriptional levels of these genes. The pattern of expression of transcriptional regulators, sigma factors, and signal transducers indicates that response to growth rate is the dominant global mechanism used for control of gene expression in
C. thermocellum.
Heterogeneity of
Aspergillus niger
Microcolonies in Liquid Shaken Cultures
Authors: de Bekker Charissa , van Veluw G. Jerre , Vinck Arman , Wiebenga L. Ad , Wösten Han A. B.
Published: December 2010

The fungus
Aspergillus niger
forms (sub)millimeter microcolonies within a liquid shaken culture. Here, we show that such microcolonies are heterogeneous with respect to size and gene expression. Microcolonies of strains expressing green fluorescent protein (GFP) from the promoter of the glucoamlyase gene
glaA
or the ferulic acid esterase gene
faeA
were sorted on the basis of diameter and fluorescence using the Complex Object Parametric Analyzer and Sorter (COPAS) technology. Statistical analysis revealed that the liquid shaken culture consisted of two populations of microcolonies that differ by 90 μm in diameter. The population of small microcolonies of strains expressing GFP from the
glaA
or
faeA
promoter comprised 39% and 25% of the culture, respectively. Two populations of microcolonies could also be distinguished when the expression of GFP in these strains was analyzed. The population expressing a low level of GFP consisted of 68% and 44% of the culture, respectively. We also show that mRNA accumulation is heterogeneous within microcolonies of
A. niger
. Central and peripheral parts of the mycelium were isolated with laser microdissection and pressure catapulting (LMPC), and RNA from these samples was used for quantitative PCR analysis. This analysis showed that the RNA content per hypha was about 45 times higher at the periphery than in the center of the microcolony. Our data imply that the protein production of
A. niger
can be improved in industrial fermentations by reducing the heterogeneity within the culture.
Induction of a State of Iron Limitation in Uropathogenic
Escherichia coli
CFT073 by Cranberry-Derived Proanthocyanidins as Revealed by Microarray Analysis
Authors: Hidalgo Gabriela , Ponton André , Fatisson Julien , O'May Che , Asadishad Bahareh , Schinner Tim , Tufenkji Nathalie
Published: December 2010

Transcriptional profiles of uropathogenic
Escherichia coli
CFT073 exposed to cranberry-derived proanthocyanidins (PACs) were determined. Our results indicate that bacteria grown on media supplemented with PACs were iron deprived. To our knowledge, this is the first time that PACs have been shown to induce a state of iron limitation in this bacterium.
Spatial Distribution of Bacterial Colonies in a Model Cheese
Authors: Jeanson S. , Chadœuf J. , Madec M. N. , Aly S. , Floury J. , Brocklehurst T. F. , Lortal S.
Published: December 2010

In most ripened cheeses, bacteria are responsible for the ripening process. Immobilized in the cheese matrix, they grow as colonies. Therefore, their distribution as well as the distance between them are of major importance for ripening steps since metabolites diffuse within the cheese matrix. No data are available to date about the spatial distribution of bacterial colonies in cheese. This is the first study to model the distribution of bacterial colonies in a food-type matrix using nondestructive techniques. We compared (i) the mean theoretical three-dimensional (3D) distances between colonies calculated on the basis of inoculation levels and considering colony distribution to be random and (ii) experimental measurements using confocal microscopy photographs of fluorescent colonies of a
Lactococcus lactis
strain producing green fluorescent protein (GFP) inoculated, at different levels, into a model cheese made by ultrafiltration (UF). Enumerations showed that the final numbers of cells were identical whatever the inoculation level (10
4
to 10
7
CFU/g). Bacterial colonies were shown to be randomly distributed, fitting Poisson's model. The initial inoculation level strongly influenced the mean distances between colonies (from 25 μm to 250 μm) and also their mean diameters. The lower the inoculation level, the larger the colonies were and the further away from each other. Multiplying the inoculation level by 50 multiplied the interfacial area of exchange with the cheese matrix by 7 for the same cell biomass. We finally suggested that final cell numbers should be discussed together with inoculation levels to take into account the distribution and, consequently, the interfacial area of colonies, which can have a significant influence on the cheese-ripening process on a microscopic scale.
Bacterial Communities Associated with the Lichen Symbiosis
Authors: Bates Scott T. , Cropsey Garrett W. G. , Caporaso J. Gregory , Knight Rob , Fierer Noah
Published: December 2010

Lichens are commonly described as a mutualistic symbiosis between fungi and “algae” (
Chlorophyta
or
Cyanobacteria
); however, they also have internal bacterial communities. Recent research suggests that lichen-associated microbes are an integral component of lichen thalli and that the classical view of this symbiotic relationship should be expanded to include bacteria. However, we still have a limited understanding of the phylogenetic structure of these communities and their variability across lichen species. To address these knowledge gaps, we used bar-coded pyrosequencing to survey the bacterial communities associated with lichens. Bacterial sequences obtained from four lichen species at multiple locations on rock outcrops suggested that each lichen species harbored a distinct community and that all communities were dominated by
Alphaproteobacteria
. Across all samples, we recovered numerous bacterial phylotypes that were closely related to sequences isolated from lichens in prior investigations, including those from a lichen-associated
Rhizobiales
lineage (LAR1; putative N
2
fixers). LAR1-related phylotypes were relatively abundant and were found in all four lichen species, and many sequences closely related to other known N
2
fixers (e.g.,
Azospirillum
,
Bradyrhizobium
, and
Frankia
) were recovered. Our findings confirm the presence of highly structured bacterial communities within lichens and provide additional evidence that these bacteria may serve distinct functional roles within lichen symbioses.
The Mode of Cell Wall Growth in Selected Archaea Is Similar to the General Mode of Cell Wall Growth in Bacteria as Revealed by Fluorescent Dye Analysis
Authors: Wirth Reinhard , Bellack Annett , Bertl Markus , Bilek Yvonne , Heimerl Thomas , Herzog Bastian , Leisner Madeleine , Probst Alexander , Rachel Reinhard , Sarbu Christina , Schopf Simone , Wanner Gerhard
Published: December 2010

The surfaces of 8 bacterial and 23 archaeal species, including many hyperthermophilic
Archaea
, could be stained using succinimidyl esters of fluorescent dyes. This allowed us for the first time to analyze the mode of cell wall growth in
Archaea
by subculturing stained cells. The data obtained show that incorporation of new cell wall material in
Archaea
follows the pattern observed for
Bacteria
: in the coccoid species
Pyrococcus furiosus
incorporation was in the region of septum formation while for the rod-shaped species
Methanopyrus kandleri
and
Methanothermus sociabilis
, a diffuse incorporation of cell wall material over the cell length was observed. Cell surface appendages like fimbriae/pili, fibers, or flagella were detectable by fluorescence staining only in a very few cases although their presence was proven by electron microscopy. Our data in addition prove that Alexa Fluor dyes can be used for
in situ
analyses at temperatures up to 100°C.
New Insights into the Lpt Machinery for Lipopolysaccharide Transport to the Cell Surface: LptA-LptC Interaction and LptA Stability as Sensors of a Properly Assembled Transenvelope Complex
Authors: Sperandeo Paola , Villa Riccardo , Martorana Alessandra M. , Šamalikova Maria , Grandori Rita , Dehò Gianni , Polissi Alessandra
Published: December 2010

Lipopolysaccharide (LPS) is a major glycolipid present in the outer membrane (OM) of Gram-negative bacteria. The peculiar permeability barrier of the OM is due to the presence of LPS at the outer leaflet of this membrane that prevents many toxic compounds from entering the cell. In
Escherichia coli
LPS synthesized inside the cell is first translocated over the inner membrane (IM) by the essential MsbA flippase; then, seven essential Lpt proteins located in the IM (LptBCDF), in the periplasm (LptA), and in the OM (LptDE) are responsible for LPS transport across the periplasmic space and its assembly at the cell surface. The Lpt proteins constitute a transenvelope complex spanning IM and OM that appears to operate as a single device. We show here that
in vivo
LptA and LptC physically interact, forming a stable complex and, based on the analysis of loss-of-function mutations in LptC, we suggest that the C-terminal region of LptC is implicated in LptA binding. Moreover, we show that defects in Lpt components of either IM or OM result in LptA degradation; thus, LptA abundance in the cell appears to be a marker of properly bridged IM and OM. Collectively, our data support the recently proposed transenvelope model for LPS transport.
A Novel
cdsAB
Operon Is Involved in the Uptake of
l
-Cysteine and Participates in the Pathogenesis of
Yersinia ruckeri
Authors: Méndez Jessica , Reimundo Pilar , Pérez-Pascual David , Navais Roberto , Gómez Esther , Guijarro José A.
Published: December 2010

Application of
in vivo
expression technology (IVET) to
Yersinia ruckeri
, an important fish pathogen, allowed the identification of two adjacent genes that represent a novel bacterial system involved in the uptake and degradation of
l
-cysteine. Analysis of the translational products of both genes showed permease domains (open reading frame 1 [ORF1]) and amino acid position identities (ORF2) with the
l
-cysteine desulfidase from
Methanocaldococcus jannaschii
, a new type of enzyme involved in the breakdown of
l
-cysteine. The operon was named
cdsAB
(cysteine desulfidase) and is found widely in anaerobic and facultative bacteria.
cdsAB
promoter analysis using
lacZY
gene fusion showed highest induction in the presence of
l
-cysteine. Two
cdsA
and
cdsB
mutant strains were generated. The limited toxic effect and the low utilization of
l
-cysteine observed in the
cdsA
mutant, together with radiolabeled experiments, strongly suggested that CdsA is an
l
-cysteine permease. Fifty percent lethal dose (LD
50
) and competence index experiments showed that both the
cdsA
and
cdsB
loci were involved in the pathogenesis of the bacteria. In conclusion, this study has shown for the first time in bacteria the existence of an
l
-cysteine uptake system that together with an additional
l
-cysteine desulfidase-encoding gene constitutes a novel operon involved in bacterial virulence.
Antibiotics and UV Radiation Induce Competence for Natural Transformation inLegionella pneumophila
Authors: Charpentier Xavier , Kay Elisabeth , Schneider Dominique , Shuman Howard A.
Published: December 2010

Natural transformation by competence is a major mechanism of horizontal gene transfer in bacteria. Competence is defined as the genetically programmed physiological state that enables bacteria to actively take up DNA from the environment. The conditions that signal competence development are multiple and elusive, complicating the understanding of its evolutionary significance. We used expression of the competence genecomEAas a reporter of competence development and screened several hundred molecules for their ability to induce competence in the freshwater living pathogenLegionella pneumophila. We found thatcomEAexpression is induced by chronic exposure to genotoxic molecules such as mitomycin C and antibiotics of the fluoroquinolone family. These results indicated that, inL. pneumophila, competence may be a response to genotoxic stress. Sunlight-emitted UV light represents a major source of genotoxic stress in the environment and we found that exposure to UV radiation effectively induces competence development. For the first time, we show that genetic exchanges by natural transformation occur within an UV-stressed population. Genotoxic stress induces the RecA-dependent SOS response in many bacteria. However, genetic and phenotypic evidence suggest thatL. pneumophilalacks a prototypic SOS response and competence development in response to genotoxic stress is RecA independent. Our results strengthen the hypothesis that competence may have evolved as a DNA damage response in SOS-deficient bacteria. This parasexual response to DNA damage may have enabledL. pneumophilato acquire and propagate foreign genes, contributing to the emergence of this human pathogen.
Labeling and Enzyme Studies of the Central Carbon Metabolism in
Metallosphaera sedula
Authors: Estelmann Sebastian , Hügler Michael , Eisenreich Wolfgang , Werner Katharina , Berg Ivan A. , Ramos-Vera W. Hugo , Say Rafael F. , Kockelkorn Daniel , Gad′on Nasser , Fuchs Georg
Published: December 2010

Metallosphaera sedula
(
Sulfolobales
,
Crenarchaeota
) uses the 3-hydroxypropionate/4-hydroxybutyrate cycle for autotrophic carbon fixation. In this pathway, acetyl-coenzyme A (CoA) and succinyl-CoA are the only intermediates that can be considered common to the central carbon metabolism. We addressed the question of which intermediate of the cycle most biosynthetic routes branch off. We labeled autotrophically growing cells by using 4-hydroxy[1-
14
C]butyrate and [1,4-
13
C
1
]succinate, respectively, as precursors for biosynthesis. The labeling patterns of protein-derived amino acids verified the operation of the proposed carbon fixation cycle, in which 4-hydroxybutyrate is converted to two molecules of acetyl-CoA. The results also showed that major biosynthetic flux does not occur via acetyl-CoA, except for the formation of building blocks that are directly derived from acetyl-CoA. Notably, acetyl-CoA is not assimilated via reductive carboxylation to pyruvate. Rather, our data suggest that the majority of anabolic precursors are derived from succinyl-CoA, which is removed from the cycle via oxidation to malate and oxaloacetate. These C
4
intermediates yield pyruvate and phosphoenolpyruvate (PEP). Enzyme activities that are required for forming intermediates from succinyl-CoA were detected, including enzymes catalyzing gluconeogenesis from PEP. This study completes the picture of the central carbon metabolism in autotrophic
Sulfolobales
by connecting the autotrophic carbon fixation cycle to the formation of central carbon precursor metabolites.
Escherichia coli
Dihydropyrimidine Dehydrogenase Is a Novel NAD-Dependent Heterotetramer Essential for the Production of 5,6-Dihydrouracil
Authors: Hidese Ryota , Mihara Hisaaki , Kurihara Tatsuo , Esaki Nobuyoshi
Published: December 2010

The reductive pyrimidine catabolic pathway is absent in
Escherichia coli
. However, the bacterium contains an enzyme homologous to mammalian dihydropyrimidine dehydrogenase. Here, we show that
E. coli
dihydropyrimidine dehydrogenase is the first member of a novel NADH-dependent subclass of iron-sulfur flavoenzymes catalyzing the conversion of uracil to 5,6-dihydrouracil
in vivo
.
SigG Does Not Control Gene Expression in Response to DNA Damage in
Mycobacterium tuberculosis
H37Rv
Authors: Smollett Katherine L. , Dawson Lisa F. , Davis Elaine O.
Published: December 2010

Expression of the
Mycobacterium tuberculosis sigG
sigma factor was induced by a variety of DNA-damaging agents, but inactivation of
sigG
did not affect induction of gene expression or bacterial survival under these conditions. Therefore, SigG does not control the DNA repair response of
M. tuberculosis
H37Rv.
Requirement of the
agr
Locus for Colony Spreading of
Staphylococcus aureus
Authors: Tsompanidou Eleni , Sibbald Mark J. J. B. , Chlebowicz Monika A. , Dreisbach Annette , Back Jaap Willem , van Dijl Jan Maarten , Buist Girbe , Denham Emma L.
Published: December 2010

The important human pathogen
Staphylococcus aureus
is known to spread on soft agar plates. Here, we show that colony spreading of
S. aureus
involves the
agr
quorum-sensing system. This finding can be related to the
agr
-dependent expression of biosurfactants, such as phenol-soluble modulins, suggesting a connection between spreading motility and virulence.
Acupuncture for Erectile Dysfunction in a Non-Diabetic Haemodialysis Patient: A Case Report
Authors: Kim Kun Hyung , Kim Tae-Hun , Kang Jung Won , Lee Myeong Soo , Kim Jong-In , Choi Jun-Yong , Sul Jae-Uk , Choi Sun Mi
Published: December 2010

Erectile dysfunction (ED) significantly affects the quality of life in male haemodialysis patients. This study reports the observed effects of acupuncture for ED in a non-diabetic haemodialysis patient. A 43-year-old man undergoing haemodialysis received 12 sessions of manual acupuncture over 6 weeks and was observed for 6 months after the end of treatment. Total International Index of Erectile Function Questionnaire scores of the patient were changed from 32 at baseline to 60 at post-treatment evaluation, which means there was a significant improvement of ED. All International Index of Erectile Function subscales also increased. This beneficial effect lasted up to 6 months after the end of treatment. No adverse events were observed. An interview revealed that the lowered self-esteem of the patient was restored with the improvement of ED following acupuncture. Further controlled studies are needed to determine whether acupuncture might be a feasible and useful treatment option for erectile dysfunction in haemodialysis patients.
CpG island methylator phenotype of cell-cycle regulators associated with TNM stage and poor prognosis in patients with oesophageal squamous cell carcinoma
Authors: Ling Yang , Huang Guoliang , Fan Lieying , Wei Lixin , Zhu Jing , Liu Yongping , Zhu Changtai , Zhang Changsong
Published: December 2010

Aims

CpG island methylator phenotype (CIMP) involves the targeting of multiple genes by promoter hypermethylation, and the cell-cycle regulatory proteins often change in human neoplasms. To gain insight into the role of epigenetic aberration of cell-cycle regulator genes in oesophagus squamous cell carcinoma (ESCC), the authors determined the hypermethylation profile in ESCC.

Methods

The promoter methylation status of nine cell-cycle regulator genes was examined in 50 ESCC, 50 dysplastic tissues and 50 normal epithelial tissues by methylation-specific PCR.

Results

The frequency of promoter methylation was 52% forp14, 44% forp15, 50% forp16, 56% forp21, 38% forp27, 8% forp53, 42% forp57, 36% forp73, and 44% forRB1of 50 ESCC. CIMP+ was detected in 54% (27/50) of ESCC and 8% (4/50) of dysplastic tissues; no CIMP+ was present in normal epithelial tissues (p<0.001). The results show that promoter methylation ofp14,p15,p16,p21,p27,p57andp73was far more common in ESCC samples with CIMP+ than those with CIMP−. A significant difference between CIMP status and TNM stage and metastasis was found in ESCC (p<0.05). Patients with ESCC with CIMP+ had poorer 4-year survival than those with CIMP−.

Conclusions

The results suggest that CIMP of a subset of cell-cycle regulatory genes has an important role in the pathogenesis and progression of ESCC.
Oral contraceptive and hormone replacement therapy in women with cerebral aneurysms
Authors: Chen Michael , Ouyang Bichun , Goldstein-Smith Lindsay , Feldman Lisa
Published: December 2010

Background

It is well known that cerebral aneurysms occur more frequently in women, with numerous studies suggesting a role for hormones in aneurysm pathogenesis. Estrogen promotes normal physiologic vascular endothelial function but also fluctuates during the menstrual cycle and drops significantly at menopause.

Methods

A retrospective, case control study was conducted to determine if exogenous estrogen use, which stabilizes estradiol levels, had any association with the presence of cerebral aneurysms. 60 women with intradural cerebral aneurysms were interviewed about their basic medical and female reproductive health histories, including oral contraceptive pill and hormone replacement therapy use and duration of use. This information was compared with the same data collected from women in the general public, as represented by 4682 women contacted through random digit phone dialing in the National Institute of Child Health and Human Development sponsored Contraceptive and Reproductive Experiences Study, published in 2002.

Results

Multivariate logistic regression showed a significant association between a lower rate of oral contraceptive (OR 2.1, CI 1.17 to 3.81; p=0.01) and hormone replacement therapy (OR 3.09, CI 1.54 to 6.22; p=0.002) use and the presence of a cerebral aneurysm.

Conclusion

These data suggest that exposure to exogenous estrogen agents in women is associated with a lower frequency of cerebral aneurysms.
Associations between the prevalence of Mollicutes andMycoplasma bovisand health and performance in stocker calves
Authors: Hanzlicek G. A. , White B. J. , Renter D. G. , Anderson D. E. , Larson R. L.
Published: December 2010

A longitudinal cross‐sectional time‐series study was carried out to determine the prevalence of nasal mycoplasma carriage, serostatus and seroconversion, and to evaluate the associations between these parameters and health and performance in weaned beef calves during a 42‐day feeding period. Nasal swabs and serum were collected on days 0 (arrival), 10, 42 and at the first incidence of bovine respiratory disease complex. The samples were evaluated for Mollicutes (by culture),Mycoplasma bovis(by PCR) and serum antibody toM bovis. On day 0, 90.4 per cent of the calves were Mollicutes nasal culture‐positive. The seroprevalence ofM boviswas 26.6 per cent on day 0 and 98.2 per cent by day 42 (P<0.05). Seroconversion toM bovisbetween days 0 and 42 was significantly associated (P=0.04) with lower weight gain. Weight gain was greater in calves that were PCR‐negative forM bovison day 10 (P=0.01).The percentage of calves seropositive toM bovisincreased throughout the study, indicating exposure and an immunological response to the organism. Although associations with health outcomes were not identified, seroconversion toM boviswas associated with a decreased rate of weight gain during the study period.
Modeling of low-cement extruded curb of concrete-faced rockfill dam
Authors: Zhang Ga , Zhang Jian-Min
Published: December 2010

As the key structure of a practical construction technique, the low-cement extruded curb has been widely used in recent concrete-faced rockfill dams (CFRDs). The extruded curb exhibits significant interactions with the neighboring gravels and with the face slab. These interactions were investigated using element tests, and a new model was proposed. This model is composed of three parts: (i) the equivalent slab that is described using an ideal elastoplasticity model, (ii) the equivalent interface between the curb and the gravel cushion layer that is described using an elastoplasticity damage model, and (iii) the interface between the curb and the face slab that is described using a modified ideal elastoplasticity model. This model was verified via a two-dimensional numerical simulation of an ideal CFRD to capture the main behavior of the extruded curb with interactions between the extruded curb and the neighboring soil – face slab, employing a significantly smaller number of elements and a shorter calculation than direct simulation. The model was used to perform a three-dimensional stress–displacement analysis of the Bakun CFRD (205 m in height), and the results showed that the extruded curb causes a change in the stress of the face slab.
A NOTE ON THE IMPLEMENTATION OF POINCARÉ SYMMETRY IN NONCOMMUTATIVE FIELD THEORY
Authors: CORTESE IGNACIO , GARCÍA J. ANTONIO
Published: December 2010

We argue that Poincaré symmetry can be implemented in noncommutative field theory (NCFT) if we allow the parameter of noncommutative deformation θμν to change as a two-tensor under the corresponding space–time symmetry. The implementation is consistent with the definition of θμν in terms of space–time coordinates and with the Moyal star product. Inspired by the standard definition of a variational symmetry we found a universal way to correct the implementation of the Poincaré symmetry by a term proportional to the variation of θμν in such a way that the new transformation define a symmetry of the theory. Finally we present as an example the case of NCYM theory and comment about the obstructions to implement generalized space–time symmetries in NCFT-like conformal or diffeomorphism transformations.
CRITICAL PHENOMENA IN DEEP INELASTIC SCATTERING
Authors: JENKOVSZKY L. L. , NAGY ANDREA , TROSHIN S. M. , TURÓCI JOLÁN , TYURIN N. E.
Published: December 2010

Saturation in deep inelastic scattering and deeply virtual Compton scattering is associated with a phase transition between the partonic gas, typical of moderate x and Q2, and partonic fluid appearing at increasing Q2 and decreasing Bjorken x. In this paper we do not intend to propose another parametrization of the structure function; instead we suggest a new insight into the internal structure of the nucleon, as seen in deep inelastic scattering, and its connection with that revealed in high-energy nucleons and heavy-ion collisions.
THE INFLUENCE OF ELECTRIC FIELD ON THE GROUND-STATE LIFETIME OF POLARON IN A PARABOLIC QUANTUM DOT
Authors: LI WEI-PING , YIN JI-WEN , YU YI-FU , XIAO JING-LIN
Published: December 2010

The ground-state energy of polaron was obtained with strong electron-LO-phonon coupling by using a variational method of the Pekar type in a parabolic quantum dot (QD). Quantum transition occurs in the quantum system due to the electron-phonon interaction and the influence of temperature. That is the polaron transition from the ground-state to the first-excited state after absorbing a LO-phonon and it causes the changing of the polaron lifetime. Numerical calculations are performed and the results illustrate the relations of the ground-state lifetime of the polaron on the ground-state energy of polaron, the electric field strength, the temperature, the electron-LO-phonon coupling strength and the confinement length of the quantum dot.
LINEAR CONDUCTANCE AND TUNNEL MAGNETORESISTANCE IN A RASHBA QUANTUM DOT RING COUPLED TO FERROMAGNETIC LEADS
Authors: CHI FENG , HUANG LING , ZHAO JIA
Published: December 2010

Spin-dependent electronic transport through a quantum ring with a quantum dot (QD) inserted in one of its arms is investigated within the Keldysh Green's function theory. We consider that the ring is connected to external ferromagnetic electrodes and there is Rashba spin-orbit interaction (SOI) in the QD. It is found that the anomalous tunnel magnetoresistance (TMR) peak originated from the electron correlations is split into two by the direct coupling between the two leads, with the two normal Coulomb resonances unchanged. The peak position and the magnitude of the conductance and the TMR can be controlled in terms of the SOI-induced phase factor, which can be adjusted by the gate voltage or the structure parameters. The present device should be realizable within present technology and may have practical usage in spintronics.
HYPERCOMPLEX CROSS-CORRELATION OF DNA SEQUENCES
Authors: SHU JIAN-JUN , LI YAJING
Published: December 2010

A hypercomplex representation of DNA is proposed to facilitate comparing DNA sequences with fuzzy composition. With the hypercomplex number representation, the conventional sequence analysis method, such as, dot matrix analysis, dynamic programming, and cross-correlation method have been extended and improved to align DNA sequences with fuzzy composition. The hypercomplex dot matrix analysis can provide more control over the degree of alignment desired. A new scoring system has been proposed to accommodate the hypercomplex number representation of DNA and integrated with dynamic programming alignment method. By using hypercomplex cross-correlation, the match and mismatch alignment information between two aligned DNA sequences are separately stored in the resultant real part and imaginary parts respectively. The mismatch alignment information is very useful to refine consensus sequence based motif scanning.
TUMOR ANGIOGENESIS BASED ANALYTICAL MODEL FOR THE ASSESSMENT OF MCT AND MTD CHEMOTHERAPEUTIC STRATEGIES IN CANCER
Authors: MAJUMDER DURJOY
Published: December 2010

Solid tumor survives by the process of angiogenesis. In this process micro-vessels are generated around it. Two factors govern this process. One is Tumor Angiogenic Factor (TAF) secreted by the tumor cells and another is tissue Fibronectin (FNT) concentration in the extra-cellular space. These two factors help in mobilization of endothelial cells from nearby blood vessels, a process called angiogenesis. Metronomic chemotherapeutic (MCT) procedure is targeted at this angiogenic microvessels at the cancer milieu and thereby, limits the growth of cancer cells. Here, we have developed a fluid dynamical based analytical model. The model comprises tumor system and a microvasculature system around it. Another characteristic of the developed model is the incorporation of a tracking procedure of either the tumor or microvasculature system from the peripheral blood. Therefore, this analytical method makes a correlation between tumor system, its micro-vasculature system and the peripheral blood circulatory system. With this analytical armamentarium we have tested the effectiveness of MCT in comparison with the conventional maximum tolerable dosing (MTD) strategy. Our simulation result reveals that under the condition MCT is better compared to MTD in controlling tumor growth in a dynamical sense. The advantage of this analytical model is that the tumor system dynamics can be effectively traced through both invasive and non-invasive procedure as and when required.