659 research outputs found
Sequence Analysis of Inducible Prophage phIS3501 Integrated into the Haemolysin II Gene of Bacillus thuringiensis var israelensis ATCC35646
Diarrheic food poisoning by bacteria of the Bacillus cereus group is mostly due to several toxins encoded in the genomes. One of them, cytotoxin K, was recently identified as responsible for severe necrotic syndromes. Cytotoxin K is similar to a class of proteins encoded by genes usually annotated as haemolysin II (hlyII) in the majority of genomes of the B. cereus group. The partially sequenced genome of Bacillus thuringiensis var israelensis ATCC35646 contains several potentially induced prophages, one of them integrated into the hlyII gene. We determined the complete sequence and established the genomic organization of this prophage-designated phIS3501. During induction of excision of this prophage with mitomycin C, intact hlyII gene is formed, thus providing to cells a genetic ability to synthesize the active toxin. Therefore, this prophage, upon its excision, can be implicated in the regulation of synthesis of the active toxin and thus in the virulence of bacterial host. A generality of selection for such systems in bacterial pathogens is indicated by the similarity of this genetic arrangement to that of Staphylococcus aureus β-haemolysin
On the equivalence of different formulations of the M Theory five--brane
We show that the field equations for the supercoordinates and the self--dual
antisymmetric tensor field derived from the recently constructed
kappa-invariant action for the M theory five-brane are equivalent to the
equations of motion obtained in the doubly supersymmetric geometrical approach
at the worldvolume component level.Comment: TeX file, 12 page
The heat and mass transfer modeling with time delay
Nonlinear hyperbolic reaction-diffusion equations with a delay in time are investigated. All equations considered here contain one arbitrary function. Exact solutions are also presented for more complex nonlinear equations in which delay arbitrarily depends on time. Exact solutions with a generalized separation of variables are found. For special cases, new exact solutions in the form of a traveling waves are obtained, some of which can be represented in terms of elementary functions. All of these solutions contain free (arbitrary) parameters, so that one can use them to solve modeling problems of heat and mass transfer with relaxation phenomena
The type IIA NS5--Brane
The kappa--invariant worldvolume action for the NS5--brane in a D=10 type IIA
supergravity background is obtained by carrying out the dimensional reduction
of the M5--brane action.Comment: 18 pages, Latex. Comments and one Ref. added, typos correcte
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The Genetically Remote Pathogenic Strain NVH391-98 of the Bacillus cereus Group Represents the Cluster of Thermophilic Strains
Bacteria of the Bacillus cereus group are known to cause food poisoning. A rare phylogenetically remote strain, NVH391-98, was recently characterized to encode a particularly efficient cytotoxin K presumably responsible for food poisoning. This pathogenic strain and its close relatives can be phenotypically distinguished from other strains of the B. cereus group by the inability to grow at temperatures below 17 degrees C and by the ability to grow at temperatures from 48 to 53 degrees C. A temperate phage, phBC391A2, residing in the genome of NVH391-98 allows us to distinguish the three known members of this thermophilic strain cluster
Various Faces of Type IIA Supergravity
We derive a duality-symmetric action for type IIA D=10 supergravity by the
Kaluza-Klein dimensional reduction of the duality-symmetric action for D=11
supergravity with the 3-form and 6-form gauge field. We then double the bosonic
fields arising as a result of the Kaluza-Klein dimensional reduction and add
mass terms to embrace the Romans's version, so that in its final form the
bosonic part of the action contains the dilaton, NS-NS and RR potentials of the
standard type IIA supergravity as well as their duals, the corresponding
duality relations are deduced directly from the action. We discuss the relation
of our approach to the doubled field formalism by Cremmer, Julia, Lu and Pope,
complete the extension of this construction to the supersymmetric case and lift
it onto the level of the proper duality-symmetric action. We also find a new
dual formulation of type IIA D=10 supergravity in which the NS-NS two-form
potential is replaced with its six-form counterpart. A truncation of this dual
model produces the Chamseddine's version of N=1, D=10 supergravity.Comment: 36 pages, plain Late
d-Orthogonal polynomials and su(2)
Two families of d-orthogonal polynomials related to su(2) are identified and
studied. The algebraic setting allows their full characterization (explicit
expressions, recurrence relations, difference equations, generating functions,
etc.) of those polynomials. In the limit where su(2) contracts to the
Heisenberg-Weyl algebra h_1, these polynomials tend to the standard Meixner
polynomials and d-Charlier polynomials, respectively.Comment: 22 page
Generalized action principle and extrinsic geometry for N=1 superparticle
It is proposed the generalized action functional for N=1 superparticle in
D=3,4,6 and 10 space-time dimensions. The superfield geometric approach
equations describing superparticle motion in terms of extrinsic geometry of the
worldline superspace are obtained on the base of the generalized action. The
off-shell superdiffeomorphism invariance (in the rheonomic sense) of the
superparticle generalized action is proved. It was demonstrated that the half
of the fermionic and one bosonic (super)fields disappear from the generalized
action in the analytical basis. Superparticle interaction with Abelian gauge
theory is considered in the framework of this formulation. The geometric
approach equations describing superparticle motion in Abelian background are
obtained.Comment: 31 pages. Late
Complete genome sequence of the industrial bacterium Bacillus licheniformis and comparisons with closely related Bacillus species
BACKGROUND: Bacillus licheniformis is a Gram-positive, spore-forming soil bacterium that is used in the biotechnology industry to manufacture enzymes, antibiotics, biochemicals and consumer products. This species is closely related to the well studied model organism Bacillus subtilis, and produces an assortment of extracellular enzymes that may contribute to nutrient cycling in nature. RESULTS: We determined the complete nucleotide sequence of the B. licheniformis ATCC 14580 genome which comprises a circular chromosome of 4,222,336 base-pairs (bp) containing 4,208 predicted protein-coding genes with an average size of 873 bp, seven rRNA operons, and 72 tRNA genes. The B. licheniformis chromosome contains large regions that are colinear with the genomes of B. subtilis and Bacillus halodurans, and approximately 80% of the predicted B. licheniformis coding sequences have B. subtilis orthologs. CONCLUSIONS: Despite the unmistakable organizational similarities between the B. licheniformis and B. subtilis genomes, there are notable differences in the numbers and locations of prophages, transposable elements and a number of extracellular enzymes and secondary metabolic pathway operons that distinguish these species. Differences include a region of more than 80 kilobases (kb) that comprises a cluster of polyketide synthase genes and a second operon of 38 kb encoding plipastatin synthase enzymes that are absent in the B. licheniformis genome. The availability of a completed genome sequence for B. licheniformis should facilitate the design and construction of improved industrial strains and allow for comparative genomics and evolutionary studies within this group of Bacillaceae
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Extending the cereus group genomics to putative food-borne pathogens of different toxicity
The cereus group represents sporulating soil bacteriacontaining pathogenic strains which may cause diarrheic or emetic foodpoisoning outbreaks. Multiple locus sequence typing revealed a presencein natural samples of these bacteria of about thirty clonal complexes.Application of genomic methods to this group was however biased due tothe major interest for representatives closely related to B. anthracis.Albeit the most important food-borne pathogens were not yet defined,existing dataindicate that they are scattered all over the phylogenetictree. The preliminary analysis of the sequences of three genomesdiscussed in this paper narrows down the gaps in our knowledge of thecereus group. The strain NVH391-98 is a rare but particularly severefood-borne pathogen. Sequencing revealed that the strain must be arepresentative of a novel bacterial species, for which the name Bacilluscytotoxis is proposed. This strain has a reduced genome size compared toother cereus group strains. Genome analysis revealed absence of sigma Bfactor and the presence of genes encoding diarrheic Nhe toxin, notdetected earlier. The strain B. cereus F837/76 represents a clonalcomplex close to that of B. anthracis. Including F837/76, three such B.cereus strains had been sequenced. Alignment of genomes suggests that B.anthracis is their common ancestor. Since such strains often emerge fromclinical cases, they merit a special attention. The third strain, KBAB4,is a typical psychrotrophe characteristic to unbiased soil communities.Phylogenic studies show that in nature it is the most active group interms of gene exchange. Genomic sequence revealed high presence ofextra-chromosomal genetic material (about 530 kb) that may account forthis phenomenon. Genes coding Nhe-like toxin were found on a big plasmidin this strain. This may indicate a potential mechanism of toxicityspread from the psychrotrophic strain community. The results of thisgenomic work and ecological compartments of different strains incite toconsider a necessity of creating prophylactic vaccines against bacteriaclosely related to NVH391-98 and F837/76. Presumably developing of suchvaccines can be based on the properties of non-pathogenic strains such asKBAB4 or ATCC14579 reported here or earlier. By comparing the proteincoding genes of strains being sequenced in this project to others weestimate the shared proteome in the cereus group to be 3,000?b200 genesand the total proteome to be 20-25,000 genes
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