Structural analysis of the core region of the lipopolysaccharides from eight serotypes of Klebsiella pneumoniae

ABSTRACT To determine the function of the wabG gene in the biosynthesis of the core lipopolysaccharide (LPS) of Klebsiella pneumoniae, we constructed wabG nonpolar mutants. Data obtained from the comparative chemical and structural analysis of LPS samples obtained from the wild type, the mutant strain, and the complemented mutant demonstrated that the wabG gene is involved in attachment toα -l-glycero-d-manno-heptopyranose II (l,d-HeppII) at the O-3 position of anα -d-galactopyranosyluronic acid (α-d-GalAp) residue. K. pneumoniae nonpolar wabG mutants were devoid of the cell-attached capsular polysaccharide but were still able to produce capsular polysaccharide. Similar results were obtained with K. pneumoniae nonpolar waaC and waaF mutants, which produce shorter LPS core molecules than do wabG mutants. Other outer core K. pneumoniae nonpolar mutants in the waa gene cluster were encapsulated. K. pneumoniae waaC, waaF, and wabG mutants were avirulent when tested in different animal models. Furthermore, these mutants were more sensitive to some hydrophobic compounds than the wild-type strains. All these characteristics were rescued by reintroduction of the waaC, waaF, and wabG genes from K. pneumoniae.

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The structure of the core region of the lipopolysaccharide from Klebsiella pneumoniae O3

European Journal of Biochemistry ◽

10.1046/j.1432-1327.2001.02047.x ◽

2001 ◽

Vol 268 (6) ◽

pp. 1722-1729 ◽

Cited By ~ 19

Author(s):

Evgeny Vinogradov ◽

Maciej Cedzynski ◽

Andrzej Ziolkowski ◽

Anna Swierzko

Keyword(s):

Klebsiella Pneumoniae ◽

Core Region ◽

The Core

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Intramitochondrial Viruses of Reptilian Cell Origin

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100094851 ◽

1972 ◽

Vol 30 ◽

pp. 318-319

Author(s):

Philip D. Lunger ◽

H. Fred Clark

Keyword(s):

Particle Production ◽

Outer Zone ◽

Density Variation ◽

Core Region ◽

Mitochondrial Membranes ◽

Virus Particles ◽

The Core ◽

Vipera Russelli ◽

Maturation Stages ◽

Type Particle

In the course of fine structure studies of spontaneous “C-type” particle production in a viper (Vipera russelli) spleen cell line, designated VSW, virus particles were frequently observed within mitochondria. The latter were usually enlarged or swollen, compared to virus-free mitochondria, and displayed a considerable degree of cristae disorganization.Intramitochondrial viruses measure 90 to 100 mμ in diameter, and consist of a nucleoid or core region of varying density and measuring approximately 45 mμ in diameter. Nucleoid density variation is presumed to reflect varying degrees of condensation, and hence maturation stages. The core region is surrounded by a less-dense outer zone presumably representing viral capsid.Particles are usually situated in peripheral regions of the mitochondrion. In most instances they appear to be lodged between loosely apposed inner and outer mitochondrial membranes.

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A Fast and Exact Greedy Algorithm for the Core–Periphery Problem

Symmetry ◽

10.3390/sym12010094 ◽

2020 ◽

Vol 12 (1) ◽

pp. 94 ◽

Cited By ~ 1

Author(s):

Dario Fasino ◽

Franca Rinaldi

Keyword(s):

Structural Analysis ◽

Optimization Problem ◽

Polynomial Time Algorithm ◽

Time Algorithm ◽

Combinatorial Optimization Problem ◽

Connected Subgraph ◽

Optimal Solutions ◽

The Core ◽

Core Set ◽

Key Concepts

The core–periphery structure is one of the key concepts in the structural analysis of complex networks. It consists of a partitioning of the node set of a given graph or network into two groups, called core and periphery, where the core nodes induce a well-connected subgraph and share connections with peripheral nodes, while the peripheral nodes are loosely connected to the core nodes and other peripheral nodes. We propose a polynomial-time algorithm to detect core–periphery structures in networks having a symmetric adjacency matrix. The core set is defined as the solution of a combinatorial optimization problem, which has a pleasant symmetry with respect to graph complementation. We provide a complete description of the optimal solutions to that problem and an exact and efficient algorithm to compute them. The proposed approach is extended to networks with loops and oriented edges. Numerical simulations are carried out on both synthetic and real-world networks to demonstrate the effectiveness and practicability of the proposed algorithm.

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On the Nature of R 136, the Central Object of 30 Dor. A Comparison by the Galactic Cluster NGC 3603

Symposium - International Astronomical Union ◽

10.1017/s0074180900040341 ◽

1984 ◽

Vol 108 ◽

pp. 257-258

Author(s):

Michael Rosa ◽

Jorge Melnick ◽

Preben Grosbol

Keyword(s):

Core Region ◽

H Ii Regions ◽

Central Object ◽

The Core ◽

Dominant Component ◽

Galactic Cluster ◽

H Ii Region

The massive H II region NGC 3603 is the closest galactic counterpart to the giant LMC nebula 30 Dor. Walborn (1973) first compared the ionizing OB/WR clusters of the two H II regions and suggested that R 136, the unresolved luminous WR + 0 type central object of 30 Dor, might be a multiple system like the core region of NGC 3603. Suggestions that the dominant component of R 136, i.e. R 136A, might be either a single or a very few supermassive and superluminous stars (Schmidt-Kaler and Feitzinger 1982, Savage et al. 1983) have recently been disputed by Moffat and Seggewiss (1983) and Melnick (1983), who have presented spectroscopic and photometric evidence to support the hypothesis of an unresolved cluster of stars. We have extended Walborn's original comparison of the apparent morphology of the two clusters by digital treatment of the images to simulate how the galactic cluster would look like if it were located in the LMC

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