scholarly journals Variation of gonococcal lipooligosaccharide structure is due to alterations in poly-G tracts in lgt genes encoding glycosyl transferases.

1996 ◽  
Vol 183 (1) ◽  
pp. 323-327 ◽  
Author(s):  
Q L Yang ◽  
E C Gotschlich
Keyword(s):  
Sequence Analysis ◽  
Neisseria Gonorrhoeae ◽  
Experimental Evidence ◽  
High Frequency ◽  
Genetic Mechanism ◽  
Frequency Variation ◽  
Alpha Chain ◽  
Glycosyl Transferases ◽  
Genes Encoding

The lipooligosaccharide (LOS) expressed by gonococci spontaneously varies its structure at high frequency, but the underlying genetic mechanism has not been described. We have previously reported that the genes encoding the glycosyl transferases responsible for the biosynthesis of the variable alpha chain of the LOS of Neisseria gonorrhoeae are located in a locus containing five genes, lgtA, lgtB, lgtC, lgtD, and lgtE. Sequence analysis showed that lgtA, lgtC, and lgtD contained poly-G tracts within the coding frames, leading to the hypothesis that shifts in the number of guanosine residues in the poly-G tracts might be responsible for the high frequency variation in structure of gonococcal LOS. We now provide experimental evidence confirming this hypothesis.

scholarly journals Conservation of the lipooligosaccharide synthesis locus lgt among strains of Neisseria gonorrhoeae: requirement for lgtE in synthesis of the 2C7 epitope and of the beta chain of strain 15253.

1996 ◽  
Vol 184 (4) ◽  
pp. 1233-1241 ◽  
Author(s):  
A L Erwin ◽  
P A Haynes ◽  
P A Rice ◽  
E C Gotschlich
Keyword(s):  
Structural Analysis ◽  
Neisseria Gonorrhoeae ◽  
Phase Variation ◽  
Deletion Mutants ◽  
Beta Chain ◽  
Alpha Chain ◽  
Glycosyl Transferases ◽  
Galactosyl Transferase ◽  
Glcnac Transferase

The present study was undertaken to examine the extent to which the lgt locus varies among strains of gonococci. This locus encodes five glycosyl transferases involved in the synthesis of the lipooligosaccharide (LOS) of Neisseria gonorrhoeae. We examined seven gonococcal strains and found that the structure of the lgt locus is conserved among six of these strains. The locus is strikingly altered in strain 15253. This is one of the few strains where extensive structural analysis of its LOS is available, and therefore, we defined the altered lgt locus and focused on the reactivity of mAB 2C7. We found that strain 15253 contains only two lgt genes, lgtA and lgtE. As in F62, lgtA encodes a GlcNAc transferase and is subject to phase variation. In addition, by analysis of deletion mutants, we found that lgtE, which encodes a galactosyl transferase that is required for elongating the alpha-chain, is also necessary for completing the beta chain.

Predicting high‐frequency variation in stream solute concentrations with water quality sensors and machine learning

2020 ◽  
Author(s):  
Mark B. Green ◽  
Linda H. Pardo ◽  
Scott W. Bailey ◽  
John L. Campbell ◽  
William H. McDowell ◽  
...  
Keyword(s):  
Machine Learning ◽  
Water Quality ◽  
High Frequency ◽  
Frequency Variation ◽  
Water Quality Sensors

scholarly journals Localization of Antibody-Binding Sites by Sequence Analysis of Cloned Pilin Genes from Neisseria Gonorrhoeae

Microbiology ◽  
1987 ◽  
Vol 133 (4) ◽  
pp. 825-833 ◽  
Author(s):  
I. J. Nicolson ◽  
A. C. F. Perry ◽  
M. Virji ◽  
J. E. Heckels ◽  
J. R. Saunders
Keyword(s):  
Sequence Analysis ◽  
Neisseria Gonorrhoeae ◽  
Binding Sites ◽  
Antibody Binding

scholarly journals Frequency variations of gravity waves interacting with a time-varying tide

2013 ◽  
Vol 31 (10) ◽  
pp. 1731-1743 ◽  
Author(s):  
C. M. Huang ◽  
S. D. Zhang ◽  
F. Yi ◽  
K. M. Huang ◽  
Y. H. Zhang ◽  
...  
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Lower Atmosphere ◽  
Horizontal Wind ◽  
Frequency Variation ◽  
Time Varying ◽  
Transient Nature ◽  
Critical Layers ◽  
Favorable Conditions ◽  
Frequency Variations

Abstract. Using a nonlinear, 2-D time-dependent numerical model, we simulate the propagation of gravity waves (GWs) in a time-varying tide. Our simulations show that when a GW packet propagates in a time-varying tidal-wind environment, not only its intrinsic frequency but also its ground-based frequency would change significantly. The tidal horizontal-wind acceleration dominates the GW frequency variation. Positive (negative) accelerations induce frequency increases (decreases) with time. More interestingly, tidal-wind acceleration near the critical layers always causes the GW frequency to increase, which may partially explain the observations that high-frequency GW components are more dominant in the middle and upper atmosphere than in the lower atmosphere. The combination of the increased ground-based frequency of propagating GWs in a time-varying tidal-wind field and the transient nature of the critical layer induced by a time-varying tidal zonal wind creates favorable conditions for GWs to penetrate their originally expected critical layers. Consequently, GWs have an impact on the background atmosphere at much higher altitudes than expected, which indicates that the dynamical effects of tidal–GW interactions are more complicated than usually taken into account by GW parameterizations in global models.

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