Antigenic polysaccharides of bacteria: 42. Structures of O-polysaccharides from two Shigella dysenteriae type 8 strains

The structure of the O-polysaccharide (O-antigen) from Shigella dysenteriae type 8 bacteria (strain 599) was corrected using modern NMR techniques (structure 1). The revisions concerned the position of the Glc residue (in the main, but not the side chain), the site of its substitution, and the configuration of the O-glycoside linkage of the GlcNAc residue. The S. dysenteriae type 8 bacterium (strain G1221), the second investigated representative, was found to produce another structural variant of the O-polysaccharide. It contains GlcNAc instead of the Glc residue in the main chain (structure 2). This data may lead to approval of division of S. dysenteriae type 8 into two subtypes:      

Rahnella aquatilis 95U003 lipopolysaccharide

The lipopolysaccharide of a new species of Enterobacteriaceae, Rahnella aquatilis 95U003, was isolated and investigated. The structural components of the lipopolysaccharide molecule, lipid A, core oligosaccharide, and O-specific polysaccharide, were isolated by mild acidic hydrolysis. In lipid A, 3-hydroxytetradecanoic (64.3%) and tetradecanoic (22.3%) acids were found to be predominant fatty acids. In fractions 1 and 2 of the core oligosaccharides, galactose (36.6 and 43.6%), mannose (35.5 and 23.5%), and glucose (42.1 and 25.3%) were shown to be the major monosaccharides. The O-specific polysaccharide consisted of regularly repeating hexasaccharide units of the following structure:      

Chemical characteristics and endotoxic activity of the lipopolysaccharide of Rahnella aquatilis 2-95

The lipopolysaccharide (LPS) from a new Enterobacteriaceae species, Rahnella aquatilis 2-95, was isolated and investigated. The structural components of the LPS molecule, namely, lipid A, core oligosaccharide, and O-specific polysaccharide, were obtained by mild acid hydrolysis. In lipid A, 3-oxytetradecanoic and tetradecanoic acids were found to be the predominant fatty acids. The major monosaccharides of the core oligosaccharide were galactose, arabinose, fucose, rhamnose, and an unidentified component. The O-specific polysaccharide was found to be assembled of a repeated trisaccharide unit of the following structure: The R. aquatilis 2-95 LPS is less toxic and more pyrogenic than the LPS from the R. aquatilis 1-95 strain studied earlier. Both acyl and phosphate groups are essential for toxic and pyrogenic activity of R. aquatilis 2-95 LPS.     

Antigenic polysaccharides of bacteria: 40. The structures of O-specific polysaccharides from <Emphasis Type="Italic">Shigella dysenteriae</Emphasis> types 3 and 9 and <Emphasis Type="Italic">S. boydii</Emphasis> type 4 revised by NMR spectroscopy

The reported structures of O-specific polysaccharides from three type strains of Shigella bacteria were corrected by modern NMR techniques. The revisions concerned the configuration of the O-glycoside linkage (S. dysenteriae type 3, structure 1), the positions of monosaccharide residue glycosylation and acetalation by pyruvic acid (S. dysenteriae type 9, structure 2), and the attachment position of the side monosaccharide chain (S. boydii type 4, structure 3).

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Bacterial antigen polysaccharides. 43. Structure for the O-specific polysaccharide of <Emphasis Type="Italic">Providencia alcalifaciens</Emphasis> O46

Acidic O-specific polysaccharide containing D-glucose, D-glucuronic acid, L-fucose, and 2-acetamido-2-deoxy-D-glucose was obtained by mild acid degradation of lipopolysaccharide from Providencia alcalifaciens O46. The following structure of the hexasaccharide repeating unit of the O-specific polysaccharide was established using methylation analysis along with ¹H and ¹³C NMR spectroscopy, including 2D ¹H, ¹H-COSY, TOCSY, ROESY, ¹H, ¹³C-HSQC, and HMQC-TOCSY experiments:

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Radiation from a pulsed dipole source in a moving magnetized plasma

The problem of radiation from a pulsed dipole source in a moving magnetized plasma described by a diagonal permittivity tensor is considered. An exact solution describing the spatiotemporal behavior of the excited electromagnetic field is obtained. The shape of an electromagnetic pulse that is generated by the source and propagates at different angles to both the direction of the external magnetic field and the direction of plasma motion is investigated. It is found that even nonrelativistic motion of the plasma medium can substantially influence the parameters of radiation from prescribed unsteady sources.     

Increase of 1-hydroxy-2-naphthoic acid concentration as a cause of temporary cessation of growth for <Emphasis Type="Italic">Arthrobacter</Emphasis> sp. K3: Kinetic analysis

Consumption of 1-hydroxy-2-naphthoic acid by strain Arthrobacter sp. K3 was investigated. Drastic increase in the substrate concentration in flow culture was shown to induce the lag phase of growth in case the initial substrate concentration in the medium was not saturating; the culture originally saturated with the substrate (S

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K _S ) was resistant to the concentration increase. In accordance with the constructed kinetic model, lag phase results from an accumulation of intermediates in the metabolic system.

     

Dynamics of a nonquasineutral plasma in a strong magnetic field

The motion of a nonquasineutral plasma in a strong magnetic field such that is analyzed. It is shown in simple examples that, when the plasma pressure and dissipation are neglected, the only dynamic process in a magnetized plasma is the evolution of the charge-separation electric field and the related magnetic field flux. The equations derived to describe this evolution are essentially the wave Grad-Shafranov equations. The solution to these equations implies that, in a turbulent Z-pinch, a steady state can exist in which the current at a supercritical level is concentrated near the pinch axis.     

Antigenic polysaccharides of bacteria: 41. Structures of the O-specific polysaccharides of <Emphasis Type="Italic">Shigella dysenteriae</Emphasis> types 4 and 5 revised by NMR spectroscopy

The earlier established structures of the acidic O-specific polysaccharides from two typical strains of the Shigella dysenteriae bacterium were revised using modern NMR spectroscopy techniques. In particular, the configurations of the glycosidic linkages of GlcNAc (S. dysenteriae type 4) and mannose (S. dysenteriae type 5) residues were corrected. In addition, the location of the sites of non-stoichiometric O-acetylation in S. dysenteriae type 4 was determined: the lateral fucose residue was shown to be occasionally O-acetylated; also, theposition of the O-acetyl group present at the stoichiometric quantity in S. dysenteriae type 5 was corrected. The revised structures of the polysaccharides studied are shown below. The known identity of the O-specific polysaccharide structures of S. dysenteriae type 5 and Escherichia coli O58 was confirmed by ¹³C NMR spectroscopy and, hence, the structure of the E. coli O58 polysaccharide should be revised in the same manner.

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where L-Rhap3Rlac2Ac is 2-O-acetyl-3-O-[(R-1-carboxyethyl]-L-rhamnose

     

A Novel Signal Processing Measure to Identify Exact and Inexact Tandem Repeat Patterns in DNA Sequences

The identification and analysis of repetitive patterns are active areas of biological and computational research. Tandem repeats in telomeres play a role in cancer and hypervariable trinucleotide tandem repeats are linked to over a dozen major neurodegenerative genetic disorders. In this paper, we present an algorithm to identify the exact and inexact repeat patterns in DNA sequences based on orthogonal exactly periodic subspace decomposition technique. Using the new measure our algorithm resolves the problems like whether the repeat pattern is of period Open image in new window or its multiple (i.e., 2 Open image in new window , 3 Open image in new window , etc.), and several other problems that were present in previous signal-processing-based algorithms. We present an efficient algorithm of Open image in new window , where Open image in new window is the length of DNA sequence and Open image in new window is the window length, for identifying repeats. The algorithm operates in two stages. In the first stage, each nucleotide is analyzed separately for periodicity, and in the second stage, the periodic information of each nucleotide is combined together to identify the tandem repeats. Datasets having exact and inexact repeats were taken up for the experimental purpose. The experimental result shows the effectiveness of the approach.     

MHD stability of a plasma in an axisymmetric open divertor configuration

For a plasma with confined in a system of two simple axisymmetric mirror cells separated by a divertor cell, a radial plasma pressure profile is obtained that is stable against convective modes and drops off to zero at the separatrix. The shape of the marginally stable pressure profile depends on the geometric parameters (such as mirror ratios and the localization of the divertor cell), the ratio of the pressure in the mirrors cells to the pressure in the divertor cell, and the degree of pressure anisotropy.     

Isolation and phylogenetic study of Rift Valley fever virus from the first imported case to China

<正>Dear Editor,Rift Valley fever(RVF)is an anthropozoonosis caused by Rift Valley fever virus(RVFV).RVFV belongs to the Phlebovirus genus in the family Bunyaviridae,which is circulating among ruminants.Human infection with RVFV is generally asymptomatic,however,minority of patients develop severe RVF diseases like encephalitis or     

Construction of an infectious cDNA clone of Tembusu virus isolated from breeder Peking ducks

正Dear Editor,Since April 2010,an outbreak of a new disease has elicited symptoms of high fever,loss of appetite,and reduction in egg production in layer ducks in eastern China;this phenomenon has now spread throughout China(Cao et al.,2011;Su et al.,2011).The causative agent of the disease was identified as Tembusu virus(TMUV),which was classified into the genus Flavivirus,     

Characterization of a recombinant Akabane mutant virus with knockout of a nonstructural protein NSs in a pregnant goat model

正Dear Editor,Akabane virus(AKAV),an orthobunyavirus,is transmitted primarily by biting midges and is widely distributed throughout the world except the Europe.AKAV was first isolated from mosquitoes in Japan(Oya et al.,1961).Although pregnant cows,ewes,and goats infected with AKAV exhibit no clinical signs of disease,in utero infections result in abortion,premature birth,stillbirth,and     

Retromer localizes to autophagosomes during HCV replication

<正>Dear Editor,Hepatitis C virus(HCV)is a positive-strand RNA virus that belongs to the genus Hepacivirus within the Flaviviridae family.HCV causes chronic liver diseases,and185 million people are infected(Messina et al.,2015).Currently,there is no approved vaccine to prevent hepatitis C.HCV induces autophagy through elevating reactive oxygen species(ROS)levels via the unfolded     

CD95-CD95L interaction mediates the growth control of MHV68 immortalized B cells by cytotoxic T cells

<正>Dear Editor,The main limitation of the viral pathogenesis study of human gammaherpesviruses Epstein-Barr virus(EBV)and Kaposi sarcoma-associated herpesvirus(KSHV)is the absence of animal model owing to the narrow host tropism of both EBV and KSHV.Murine gammaherpesvirus 68(MHV68)encodes several genes involved in     

Recombinant canarypox virus expressing the VP2 protein of infectious bursal disease virus induces protection in vaccinated SPF chickens

正Dear Editor,Infectious bursal disease virus(IBDV)causes infectious bursal disease,a highly contagious immunosuppressive disease that affects young chickens and causes economic losses in the poultry industry worldwide.IBDV replicates mainly in actively dividing B lymphocytes within the bursa of Fabricius(BF),leading to immunosuppression in affected flocks(Mahgoub et al.,2012).Viral protein 2(VP2),the only structural component of the IBDV     

Molecular typing of non-polio enteroviruses isolated from acute flaccid paralysis cases in Iran from 2010 to 2015

<正>Dear Editor,Acute flaccid paralysis(AFP)is a complex syndrome often caused by polioviruses.While most countries have eradicated wild polioviruses by vaccination,AFP still remains a health problem in these countries.Most studies have highlighted non-polio enteroviruses(NPEVs)as