bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of a Coal-Fired Natural Circulation Boiler
Authors: Bhambare K. S. , Mitra Sushanta K. , Gaitonde U. N. 
Published: May 2007

AbstractModeling of a natural circulation boiler for a coal-fired thermal power station is presented here. The boiler system is divided into seven subcomponents, and for each section, models based on conservation of mass, momentum, and energy are formulated. The pressure drop at various sections and the heat transfer coefficients are computed using empirical correlations. Solutions are obtained by using SIMULINK. The model is validated by comparing its steady state and dynamic responses with the actual plant data. Open loop responses of the model to the step changes in the operating parameters, such as pressure, temperature, steam flow, feed water flow, are also analyzed. The present model can be used for the development and design of effective boiler control systems.
Multilocus Sequence Analysis Reveals that
Vibrio harveyi
and
V. campbellii
Are Distinct Species
Authors: Thompson Fabiano L. , Gomez-Gil Bruno , Vasconcelos Ana Teresa Ribeiro , Sawabe Tomoo 
Published: May 2007

ABSTRACT

Identification and classification of
Vibrio
species have relied upon band pattern methods (e.g., amplified fragment length polymorphism) and DNA-DNA hybridization. However, data generated by these methods cannot be used to build an online electronic taxonomy. In order to overcome these limitations, we developed the first standard multilocus sequence scheme focused on the ubiquitous and pathogenic
Vibrio harveyi
species group (i.e.,
V. harveyi
,
V. campbellii
,
V. rotiferianus
, and a new as yet unnamed species). We examined a collection of 104 isolates from different geographical regions and hosts using segments of seven housekeeping genes. These two species formed separated clusters on the basis of
topA
,
pyrH
,
ftsZ
, and
mreB
gene sequences. The phylogenetic picture obtained by the other three loci, i.e.,
gyrB
,
recA
, and
gapA
, was more complex though.
V. campbellii
appeared nested within
V. harveyi
in the
recA
trees, whereas
V. harveyi
formed a tight nested cluster within
V. campbellii
by
gapA
. The
gyrB
gene had no taxonomic resolution and grouped the two species together. The fuzziness observed in these three genes seems not be related to recombination but to low divergence due to the accumulation of only a few substitutions. In spite of this, the concatenated sequences provided evidence that the two species form two separated clusters. These clusters did not arise by recombination but by accumulation of point mutations.
V. harveyi
and
V. campbellii
isolates can be readily identified through the open database resource developed in this study (
http://www.taxvibrio.lncc.br/
). We argue that the species should be defined by evolutionary criteria. Strains of the same species will share at least 95% concatenated sequence similarity using the seven loci, and, most importantly, cospecific strains will form cohesive readily recognizable phylogenetic clades.
Insect-Microbe Mutualism without Vertical Transmission: a Stinkbug Acquires a Beneficial Gut Symbiont from the Environment Every Generation
Authors: Kikuchi Yoshitomo , Hosokawa Takahiro , Fukatsu Takema 
Published: May 2007

ABSTRACT

The broad-headed bug
Riptortus clavatus
(Heteroptera: Alydidae) possesses a number of crypts at a posterior midgut region, which house a dense population of a bacterial symbiont belonging to the genus
Burkholderia
. Although the symbiont is highly prevalent (95 to 100%) in the host populations, the symbiont phylogeny did not reflect the host systematics at all. In order to understand the mechanisms underlying the promiscuous host-symbiont relationship despite the specific and prevalent association, we investigated the transmission mode and the fitness effects of the
Burkholderia
symbiont in
R. clavatus
. Inspection of eggs and a series of rearing experiments revealed that the symbiont is not vertically transmitted but is environmentally acquired by nymphal insects. The
Burkholderia
symbiont was present in the soil of the insect habitat, and a culture strain of the symbiont was successfully isolated from the insect midgut. Rearing experiments by using sterilized soybean bottles demonstrated that the cultured symbiont is able to establish a normal and efficient infection in the host insect, and the symbiont infection significantly improves the host fitness. These results indicated that
R. clavatus
postnatally acquires symbiont of a beneficial nature from the environment every generation, uncovering a previously unknown pathway through which a highly specific insect-microbe association is maintained. We suggest that the stinkbug-
Burkholderia
relationship may be regarded as an insect analogue of the well-known symbioses between plants and soil-associated microbes, such as legume-
Rhizobium
and alder-
Frankia
relationships, and we discuss the evolutionary relevance of the mutualistic but promiscuous insect-microbe association.
Identification of Polypeptides Expressed in Response to Vinyl Chloride, Ethene, and Epoxyethane in
Nocardioides
sp. Strain JS614 by Using Peptide Mass Fingerprinting
Authors: Chuang Adina S. , Mattes Timothy E. 
Published: May 2007

ABSTRACT

Enzymes expressed in response to vinyl chloride, ethene, and epoxyethane by
Nocardioides
sp. strain JS614 were identified by using a peptide mass fingerprinting (PMF) approach. PMF provided insight concerning vinyl chloride biodegradation in strain JS614 and extends the use of matrix-assisted laser desorption-ionization time of flight mass spectrometry as a tool to enhance characterization of biodegradation pathways.
Casein Fermentate of
Lactobacillus animalis
DPC6134 Contains a Range of Novel Propeptide Angiotensin-Converting Enzyme Inhibitors
Authors: Hayes M. , Stanton C. , Slattery H. , O'Sullivan O. , Hill C. , Fitzgerald G. F. , Ross R. P. 
Published: May 2007

ABSTRACT

This work evaluated the angiotensin-converting-enzyme (ACE)-inhibitory activities of a bovine sodium caseinate fermentate generated using the proteolytic capabilities of the porcine small intestinal isolate
Lactobacillus animalis
DPC6134 (NCIMB deposit 41355). The crude 10-kDa
L. animalis
DPC6134 fermentate exhibited ACE-inhibitory activity of 85.51% (±15%) and had a 50% inhibitory concentration (IC
50
) of 0.8 mg protein/ml compared to captopril, which had an IC
50
value of 0.005 mg/ml. Fractionation of the crude
L. animalis
DPC6134 fermentate by membrane filtration and reversed-phase high-performance liquid chromatography (HPLC) generated three bioactive fractions from a total of 72 fractions. Fractions 10, 19, and 43 displayed ACE-inhibitory activity percentages of 67.53 (±15), 83.71 (±19), and 42.36 (±11), respectively, where ACE inhibition was determined with 80 μl of the fractions with protein concentrations of 0.5 mg/ml. HPLC and mass spectrometry analysis identified 25 distinct peptide sequences derived from α-, β-, and κ-caseins. In silico predictions, based on the C-terminal tetrapeptide sequences, suggested that peptide NIPPLTQTPVVVPPFIQ, corresponding to β-casein f(73-89); peptide IGSENSEKTTMP, corresponding to α
s1
-casein f(201212); peptide SQSKVLPVPQ, corresponding to β-casein f(166-175); peptide MPFPKYPVEP, corresponding to β-casein f(124133); and peptide EPVLGPVRGPFP, corresponding to β-casein f(210-221), contained ACE-inhibitory activities. These peptides were chosen for chemical synthesis to confirm the ACE-inhibitory activity of the fractions. Chemically synthesized peptides displayed IC
50
values in the range of 92 μM to 790 μM. Additionally, a simulated gastrointestinal digestion confirmed that the ACE-inhibitory 10-kDa
L. animalis
DPC6134 fermentation was resistant to a cocktail of digestive enzymes found in the gastrointestinal tract.
Molecular Diversity of Methanogens in Feedlot Cattle from Ontario and Prince Edward Island, Canada
Authors: Wright André-Denis G. , Auckland Clare H. , Lynn Denis H. 
Published: May 2007

ABSTRACT

The molecular diversity of rumen methanogens in feedlot cattle and the composition of the methanogen populations in these animals from two geographic locations were investigated using 16S rRNA gene libraries prepared from pooled PCR products from 10 animals in Ontario (127 clones) and 10 animals from Prince Edward Island (114 clones). A total of 241 clones were examined, with
Methanobrevibacter ruminantium
accounting for more than one-third (85 clones) of the clones identified. From these 241 clones, 23 different 16S rRNA phylotypes were identified. Feedlot cattle from Ontario, which were fed a corn-based diet, revealed 11 phylotypes (38 clones) not found in feedlot cattle from Prince Edward Island, whereas the Prince Edward Island cattle, which were fed potato by-products as a finishing diet, had 7 phylotypes (42 clones) not found in cattle from Ontario. Five sequences, representing the remaining 161 clones (67% of the clones), were common in both herds. Of the 23 different sequences, 10 sequences (136 clones) were 89.8 to 100% similar to those from cultivated methanogens belonging to the orders
Methanobacteriales
,
Methanomicrobiales
, and
Methanosarcinales
, and the remaining 13 sequences (105 clones) were 74.1 to 75.8% similar to those from
Thermoplasma volcanium
and
Thermoplasma acidophilum
. Overall, nine possible new species were identified from the two clone libraries, including two new species belonging to the order
Methanobacteriales
and a new genus/species within the order
Methanosarcinales
. From the present survey, it is difficult to conclude whether the geographical isolation between these two herds or differences between the two finishing diets directly influenced community structure in the rumen. Further studies are warranted to properly assess the differences between these two finishing diets.
Application of Flow Cytometry to Segregated Kinetic Modeling Based on the Physiological States of Microorganisms
Authors: Quirós Covadonga , Herrero Mónica , García Luis A. , Díaz Mario 
Published: May 2007

ABSTRACT

Flow cytometry (FC) has been introduced to characterize and to assess the physiological states of microorganisms in conjunction with the classical plate-counting method. To show the applicability of the technique, in particular for the development of kinetic models, pure culture fermentation experiments were followed over time, using both prokaryotic (
Lactobacillus hilgardii
) and eukaryotic (
Saccharomyces cerevisiae
) microorganisms growing in standard culture media (MRS and YPD). The differences observed between the active and viable cells determined by FC and CFU, respectively, allowed us to determine that a large number of cells were in a viable but nonculturable (VBNC) state, which resulted in a subpopulation much larger than the damaged-cell (double-stained) subpopulation. Finally, the determination of the evolution of viable, the VBNC, and the dead cells allowed us to develop a segregated kinetic model to describe the yeast and the bacteria population dynamics and glucose consumption in batch cultures. This model, more complete than that which is traditionally used, based only on viable cell measurements, describes better the behavior and the functionality of the cultures, giving a deeper knowledge in real time about the status and the course of the bioprocesses.
Genomic Methylation: a Tool for Typing
Helicobacter pylori
Isolates
Authors: Vale Filipa F. , Vítor Jorge M. B. 
Published: May 2007

ABSTRACT

The genome sequences of three
Helicobacter pylori
strains revealed an abundant number of putative restriction and modification (R-M) systems within a small genome (1.60 to 1.67 Mb). Each R-M system includes an endonuclease that cleaves a specific DNA sequence and a DNA methyltransferase that methylates either adenosine or cytosine within the same DNA sequence. These are believed to be a defense mechanism, protecting bacteria from foreign DNA. They have been classified as selfish genetic elements; in some instances it has been shown that they are not easily lost from their host cell. Possibly because of this phenomenon, the
H. pylori
genome is very rich in R-M systems, with considerable variation in potential recognition sequences. For this reason the protective aspect of the methyltransferase gene has been proposed as a tool for typing
H. pylori
isolates. We studied the expression of
H. pylori
methyltransferases by digesting the genomic DNAs of 50 strains with 31 restriction endonucleases. We conclude that methyltransferase diversity is sufficiently high to enable the use of the genomic methylation status as a typing tool. The stability of methyltransferase expression was assessed by comparing the methylation status of genomic DNAs from strains that were isolated either from the same patient at different times or from different stomach locations (antrum and corpus). We found a group of five methyltransferases common to all tested strains. These five may be characteristic of the genetic pool analyzed, and their biological role may be important in the host/bacterium interaction.
Responses of a Thermophilic
Synechococcus
Isolate from the Microbial Mat of Octopus Spring to Light
Authors: Kilian Oliver , Steunou Anne-Soisig , Fazeli Fariba , Bailey Shaun , Bhaya Devaki , Grossman Arthur R. 
Published: May 2007

ABSTRACT

Thermophilic cyanobacteria of the genus
Synechococcus
are major contributors to photosynthetic carbon fixation in the photic zone of microbial mats in Octopus Spring, Yellowstone National Park.
Synechococcus
OS-B′ was characterized with regard to the ability to acclimate to a range of different light irradiances; it grows well at 25 to 200 μmol photons m
−2
s
−1
but dies when the irradiance is increased to 400 μmol photons m
−2
s
−1
. At 200 μmol photons m
−2
s
−1
(high light [HL]), we noted several responses that had previously been associated with HL acclimation of cyanobacteria, including cell bleaching, reduced levels of phycobilisomes and chlorophyll, and elevated levels of a specific carotenoid.
Synechococcus
OS-B′ synthesizes the carotenoids zeaxanthin and β,β-carotene and a novel myxol-anhydrohexoside. Interestingly, 77-K fluorescence emission spectra suggest that
Synechococcus
OS-B′ accumulates very small amounts of photosystem II relative to that of photosystem I. This ratio further decreased at higher growth irradiances, which may reflect potential photodamage following exposure to HL. We also noted that HL caused reduced levels of transcripts encoding phycobilisome components, particularly that for CpcH, a 20.5-kDa rod linker polypeptide. There was enhanced transcript abundance of genes encoding terminal oxidases, superoxide dismutase, tocopherol cyclase, and phytoene desaturase. Genes encoding the photosystem II D1:1 and D1:2 isoforms (
psbAI
and
psbAII
/
psbAIII
, respectively) were also regulated according to the light regimen. The results are discussed in the context of how
Synechococcus
OS-B′ may cope with high light irradiances in the high-temperature environment of the microbial mat.
Urban Feral Pigeons (
Columba livia
) as a Source for Air- and Waterborne Contamination with
Enterocytozoon bieneusi
Spores
Authors: Graczyk Thaddeus K. , Sunderland Deirdre , Rule Ana M. , da Silva Alexandre J. , Moura Iaci N. S. , Tamang Leena , Girouard Autumn S. , Schwab Kellogg J. , Breysse Patrick N. 
Published: May 2007

ABSTRACT

This study demonstrated that a person with 30 min of occupational or nonoccupational exposure to urban feral pigeons, such as exposure through the cleaning of surfaces contaminated with pigeon excrement, could inhale approximately 3.5 × 10
3
Enterocytozoon bieneusi
spores and that 1.3 × 10
3
spores could be inhaled by a nearby person.
Molecular Identification and Genetic Analysis of Norovirus Genogroups I and II in Water Environments: Comparative Analysis of Different Reverse Transcription-PCR Assays
Authors: La Rosa G. , Fontana S. , Di Grazia A. , Iaconelli M. , Pourshaban M. , Muscillo M. 
Published: May 2007

ABSTRACT
Noroviruses have received increased attention in recent years because their role as etiologic agents in acute gastroenteritis outbreaks is now clearly established. Our inability to grow them in cell culture and the lack of an animal model hinder the characterization of these viruses. More recently, molecular approaches have been used to study the genetic relationships that exist among them. In the present study, environmental samples from seawater, estuarine water, and effluents of sewage treatment plants were analyzed in order to evaluate the role of environmental surface contamination as a possible vehicle for transmission of norovirus genogroups I and II. Novel broad-range reverse transcription-PCR/nested assays targeting the region coding for the RNA-dependent RNA polymerase were developed, amplifying fragments of 516 bp and 687 bp in the nested reactions for genogroups II and I, respectively. The assays were evaluated and compared against widely used published assays. The newly designed assays provide long regions for high-confidence BLAST searches in public databases and therefore are useful diagnostic tools for molecular diagnosis and typing of human noroviruses in clinical and environmental samples, as well as for the study of molecular epidemiology and the evolution of these viruses.
Use of Selective Capture of Transcribed Sequences To Identify Genes Preferentially Expressed byStreptococcus suisupon Interaction with Porcine Brain Microvascular Endothelial Cells
Authors: Fittipaldi Nahuel , Gottschalk Marcelo , Vanier Ghyslaine , Daigle France , Harel Josée 
Published: May 2007

ABSTRACTBy using the selective capture of transcribed sequences (SCOTS) approach, we identified 28 genes preferentially expressed by the major swine pathogen and zoonotic agentStreptococcus suisupon interaction with porcine brain microvascular endothelial cells. Several of these genes may be considered newS. suiscandidate virulence factors. Results from this study demonstrate the suitability of SCOTS for the elucidation of gene expression in streptococcal species and may contribute to a better understanding of the pathogenesis ofS. suisinfections.
Pichia acaciae
Killer System: Genetic Analysis of Toxin Immunity
Authors: Paluszynski John P. , Klassen Roland , Meinhardt Friedhelm 
Published: May 2007

ABSTRACT

The gene responsible for self-protection in the
Pichia acaciae
killer plasmid system was identified by heterologous expression in
Saccharomyces cerevisiae
. Resistance profiling and conditional toxin/immunity coexpression analysis revealed dose-independent protection by pPac1-2
ORF4
and intracellular interference with toxin function, suggesting toxin reinternalization in immune killer cells.
Mass Spectrometry-Based Strategy for Direct Detection and Quantification of Some Mycotoxins Produced by
Stachybotrys
and
Aspergillus
spp. in Indoor Environments
Authors: Bloom Erica , Bal Karol , Nyman Eva , Must Aime , Larsson Lennart 
Published: May 2007

ABSTRACT

Dampness in buildings has been linked to adverse health effects, but the specific causative agents are unknown. Mycotoxins are secondary metabolites produced by molds and toxic to higher vertebrates. In this study, mass spectrometry was used to demonstrate the presence of mycotoxins predominantly produced by
Aspergillus
spp. and
Stachybotrys
spp. in buildings with either ongoing dampness or a history of water damage. Verrucarol and trichodermol, hydrolysis products of macrocyclic trichothecenes (including satratoxins), and trichodermin, predominately produced by
Stachybotrys chartarum
, were analyzed by gas chromatography-tandem mass spectrometry, whereas sterigmatocystin (mainly produced by
Aspergillus versicolor
), satratoxin G, and satratoxin H were analyzed by high-performance liquid chromatography-tandem mass spectrometry. These mycotoxin analytes were demonstrated in 45 of 62 building material samples studied, in three of eight settled dust samples, and in five of eight cultures of airborne dust samples. This is the first report on the use of tandem mass spectrometry for demonstrating mycotoxins in dust settled on surfaces above floor level in damp buildings. The direct detection of the highly toxic sterigmatocystin and macrocyclic trichothecene mycotoxins in indoor environments is important due to their potential health impacts.
EnterohemorrhagicEscherichia coliBiofilms Are Inhibited by 7-Hydroxyindole and Stimulated by Isatin
Authors: Lee Jintae , Bansal Tarun , Jayaraman Arul , Bentley William E. , Wood Thomas K. 
Published: May 2007

ABSTRACTSince indole is present at up to 500 μM in the stationary phase and is an interspecies biofilm signal (J. Lee, A. Jayaraman, and T. K. Wood, BMC Microbiol. 7:42, 2007), we investigated hydroxyindoles as biofilm signals and found them also to be nontoxic interspecies biofilm signals for enterohemorrhagicEscherichia coliO157:H7 (EHEC),E. coliK-12, andPseudomonas aeruginosa. The genetic basis of EHEC biofilm formation was also explored, and notably, virulence genes in biofilm cells were repressed compared to those in planktonic cells. In Luria-Bertani medium (LB) on polystyrene with quiescent conditions, 7-hydroxyindole decreased EHEC biofilm formation 27-fold and decreased K-12 biofilm formation 8-fold without affecting the growth of planktonic cells. 5-Hydroxyindole also decreased biofilm formation 11-fold for EHEC and 6-fold for K-12. In contrast, isatin (indole-2,3-dione) increased biofilm formation fourfold for EHEC, while it had no effect for K-12. When continuous-flow chambers were used, confocal microscopy revealed that EHEC biofilm formation was reduced 6-fold by indole and 10-fold by 7-hydroxyindole in LB. Whole-transcriptome analysis revealed that isatin represses indole synthesis by repressingtnaABC7- to 37-fold in EHEC, and extracellular indole levels were found to be 20-fold lower. Furthermore, isatin repressed the AI-2 transporterslsrABCDFGKR, while significantly inducing the flagellar genesflgABCDEFGHIJKandfliAEFGILMNOPQ(which led to a 50% increase in motility). 7-Hydroxyindole induces the biofilm inhibitor/stress regulatorycfRand repressescysADIJPU/fliC(which led to a 50% reduction in motility) andpurBCDEFHKLMNRT. Isogenic mutants showed that 7-hydroxyindole inhibitsE. colibiofilm through cysteine metabolism. 7-Hydroxyindole (500 μM) also stimulatesP. aeruginosaPAO1 biofilm formation twofold; therefore, hydroxyindoles are interspecies bacterial signals, and 7-hydroxyindole is a potent EHEC biofilm inhibitor.