scholarly journals Differences in nitric oxide steady states between arginine, hypoxanthine, uracil auxotrophs (AHU) and non-AHU strains ofNeisseria gonorrhoeaeduring anaerobic respiration in the presence of nitrite

2008 ◽  
Vol 54 (8) ◽  
pp. 639-646 ◽  
Author(s):  
Kenneth Barth ◽  
Virginia L. Clark
Keyword(s):  
Nitric Oxide ◽  
Steady State ◽  
Nitrite Reductase ◽  
Anaerobic Respiration ◽  
State Level ◽  
Cell Number ◽  
Steady State Level ◽  
No Donor ◽  
Membrane Function ◽  
Uracil Auxotrophs

Neisseria gonorrhoeae can grow by anaerobic respiration using nitrite as an alternative electron acceptor. Under these growth conditions, N. gonorrhoeae produces and degrades nitric oxide (NO), an important host defense molecule. Laboratory strain F62 has been shown to establish and maintain a NO steady-state level that is a function of the nitrite reductase/NO reductase ratio and is independent of cell number. The nitrite reductase activities (122–197 nmol NO2reduced·min–1·OD600–1) and NO reductase activities (88–155 nmol NO reduced·min–1·OD600–1) in a variety of gonococcal clinical isolates were similar to the specific activities seen in F62 (241 nmol NO2reduced·min–1·OD600–1and 88 nmol NO reduced·min–1·OD600–1, respectively). In seven gonococcal strains, the NO steady-state levels established in the presence of nitrite were similar to that of F62 (801–2121 nmol·L–1NO), while six of the strains, identified as arginine, hypoxanthine, and uracil auxotrophs (AHU), that cause asymptomatic infection in men had either two- to threefold (373–579 nmol·L–1NO) or about 100-fold (13–24 nmol·L–1NO) lower NO steady-state concentrations. All tested strains in the presence of a NO donor, 2,2′-(hydroxynitrosohydrazono)bis-ethanimine/NO, quickly lowered and maintained NO levels in the noninflammatory range of NO (<300 nmol·L–1). The generation of a NO steady-state concentration was directly affected by alterations in respiratory control in both F62 and an AHU strain, although differences in membrane function are suspected to be responsible for NO steady-state level differences in AHU strains.

scholarly journals Biochemical and genomic analysis of the denitrification pathway within the genus Neisseria

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 4093-4103 ◽  
Author(s):  
Kenneth R. Barth ◽  
Vincent M. Isabella ◽  
Virginia L. Clark
Keyword(s):  
Nitric Oxide ◽  
Steady State ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Genomic Analysis ◽  
State Level ◽  
Steady State Level ◽  
Human Pathogens ◽  
No Donor ◽  
Denitrification Genes

Since Neisseria gonorrhoeae and Neisseria meningitidis are obligate human pathogens, a comparison with commensal species of the same genus could reveal differences important in pathogenesis. The recent completion of commensal Neisseria genome draft assemblies allowed us to perform a comparison of the genes involved in the catalysis, assembly and regulation of the denitrification pathway, which has been implicated in the virulence of several bacteria. All species contained a highly conserved nitric oxide reductase (NorB) and a nitrite reductase (AniA or NirK) that was highly conserved in the catalytic but divergent in the N-terminal lipid modification and C-terminal glycosylation domains. Only Neisseria mucosa contained a nitrate reductase (Nar), and only Neisseria lactamica, Neisseria cinerea, Neisseria subflava, Neisseria flavescens and Neisseria sicca contained a nitrous oxide reductase (Nos) complex. The regulators of the denitrification genes, FNR, NarQP and NsrR, were highly conserved, except for the GAF domain of NarQ. Biochemical examination of laboratory strains revealed that all of the neisserial species tested except N. mucosa had a two- to fourfold lower nitrite reductase activity than N. gonorrhoeae, while N. meningitidis and most of the commensal Neisseria species had a two- to fourfold higher nitric oxide (NO) reductase activity. For N. meningitidis and most of the commensal Neisseria, there was a greater than fourfold reduction in the NO steady-state level in the presence of nitrite as compared with N. gonorrhoeae. All of the species tested generated an NO steady-state level in the presence of an NO donor that was similar to that of N. gonorrhoeae. The greatest difference between the Neisseria species was the lack of a functional Nos system in the pathogenic species N. gonorrhoeae and N. meningitidis.

Tacrolimus initial steady state level in post-transplant cyclophosphamide-based GvHD prophylaxis regimens

2021 ◽  
Author(s):  
Janny M. Yao ◽  
Dongyun Yang ◽  
Mary C. Clark ◽  
Salman Otoukesh ◽  
Thai Cao ◽  
...  
Keyword(s):  
Steady State ◽  
State Level ◽  
Steady State Level ◽  
Post Transplant ◽  
Gvhd Prophylaxis

Ascorbate and glutathione homeostasis in vascular smooth muscle cells: cooperation with endothelial cells

1998 ◽  
Vol 275 (4) ◽  
pp. C1031-C1039 ◽  
Author(s):  
Ilia Voskoboinik ◽  
Karin Söderholm ◽  
Ian A. Cotgreave
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Steady State ◽  
Smooth Muscle Cells ◽  
Umbilical Vein ◽  
State Level ◽  
Muscle Cells ◽  
Free Access ◽  
Steady State Level ◽  
Human Umbilical Vein

Human umbilical vein smooth muscle cells (HUVSMCs) utilize extracellular cystine, glutathione (GSH), and N-acetylcysteine (NAC) to synthesize cellular GSH. Extracellular cystine was effective from 5 μM, whereas GSH and NAC were required at 100 μM for comparable effects. The efficacy of extracellular GSH was dependent on de novo GSH synthesis, indicating a dependence on cellular γ-glutamyltransferase (glutamyl transpeptidase). Coculture of syngenetic HUVSMCs and corresponding human umbilical vein endothelial cells (HUVECs) on porous supports restricted cystine- or GSH-stimulated synthesis of HUVSMC GSH when supplied on the “luminal” endothelial side. Thus HUVSMC GSH rapidly attained a steady-state level below that achieved in the absence of interposed HUVECs. HUVSMCs also readily utilize both reduced ascorbate (AA) and oxidized dehydroascorbate (DHAA) over the range 50–500 μM. Phloretin effectively blocked both AA- and DHAA-stimulated assimilation of intracellular AA, indicating a role for a glucose transporter in their transport. Uptake of extracellular AA was also sensitive to extracellular, but not intracellular, thiol depletion. When AA was applied to the endothelial side of the coculture model, assimilation of intracellular AA in HUVSMCs was restricted to a steady-state level below that achieved by free access.

scholarly journals The steady-state level of Mg-protoporphyrin IX is not a determinant of plastid-to-nucleus signaling in Arabidopsis

2008 ◽  
Vol 105 (39) ◽  
pp. 15184-15189 ◽  
Author(s):  
N. Mochizuki ◽  
R. Tanaka ◽  
A. Tanaka ◽  
T. Masuda ◽  
A. Nagatani
Keyword(s):  
Steady State ◽  
Protoporphyrin Ix ◽  
State Level ◽  
Steady State Level

scholarly journals Expression of human beta-secretase in the mouse brain increases the steady-state level of beta-amyloid

2002 ◽  
Vol 80 (5) ◽  
pp. 799-806 ◽  
Author(s):  
Ursula Bodendorf ◽  
Simone Danner ◽  
Frauke Fischer ◽  
Muriel Stefani ◽  
Christine Sturchler-Pierrat ◽  
...  
Keyword(s):  
Steady State ◽  
Mouse Brain ◽  
State Level ◽  
Beta Amyloid ◽  
Steady State Level ◽  
Beta Secretase

Expression of a gene for mouse eucaryotic elongation factor Tu during murine erythroleukemic cell differentiation

1987 ◽  
Vol 7 (11) ◽  
pp. 3929-3936
Author(s):  
W W Roth ◽  
P W Bragg ◽  
M V Corrias ◽  
N S Reddy ◽  
J N Dholakia ◽  
...  
Keyword(s):  
Steady State ◽  
Genomic Library ◽  
Elongation Factor ◽  
State Level ◽  
Genomic Clone ◽  
Elongation Factor Tu ◽  
Steady State Level ◽  
Similar Reduction ◽  
S1 Nuclease ◽  
Murine Erythroleukemia

The eucaryotic elongation factor Tu (eEF-Tu) is a single polypeptide with an approximate Mr of 53,000. During protein synthesis eEF-Tu promotes the binding of aminoacyl-tRNA to the ribosome. To study the expression of the gene(s) for this factor, a genomic clone was isolated that contains a mouse eEF-Tu gene. We screened a phage genomic library with a synthetic oligonucleotide probe complementary to a region of the Saccharomyces cerevisiae and Artemia sp. eEF-Tu genes which codes for an area that is highly conserved between both yeast and Artemia sp. eEF-Tu. From approximately 75,000 phage plaques we obtained five isolates with apparently identical inserts. All five clones contained a 3.8-kilobase EcoRI fragment that hybridized to additional oligonucleotide probes corresponding to different conserved regions of eEF-Tu. We sequenced the 5' end of one genomic clone and determined the length of the cloned fragment that was protected by eEF-Tu mRNA in S1 nuclease protection assays. A quantitative S1 nuclease protection assay was used to compare the relative steady-state levels of eEF-Tu mRNA in total mRNA in total RNA isolated from hexamethylene-bisacetamide-induced murine erythroleukemia cells. The results show a dramatic reduction in the steady-state level of eEF-Tu mRNA as differentiation proceeds. A similar reduction in transcription of eEF-Tu mRNA was observed in isolated nuclei. Finally, we examined the in vivo synthesis of eEF-Tu during differentiation and found that it declined in a manner parallel to the decline in the steady-state level of eEF-Tu mRNA. In addition, we have isolated and sequenced a cDNA clone for mouse eEF-Tu. The derived amino acid sequence is compared with sequences from other eucaryotes.

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