659 research outputs found

    Sequence Analysis of Inducible Prophage phIS3501 Integrated into the Haemolysin II Gene of Bacillus thuringiensis var israelensis ATCC35646

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    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

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    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

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    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

    Various Faces of Type IIA Supergravity

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    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)

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    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

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    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

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    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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