scholarly journals Listeria monocytogenes 10403S Alternative Sigma-54 Factor σL Has a Negative Role on Survival Ability Under Bile Exposure

2021 ◽  
Vol 12 ◽  
Author(s):  
Atsadang Boonmee ◽  
Haley F. Oliver ◽  
Soraya Chaturongakul
Keyword(s):  
Listeria Monocytogenes ◽  
Triple Mutant ◽  
Σ Factor ◽  
Bile Resistance ◽  
Quadruple Mutant ◽  
Bile Fluid ◽  
Negative Role ◽  
Pass Through ◽  
Isogenic Mutants

Listeria monocytogenes is a Gram-positive bacterium causing listeriosis in animals and humans. To initiate a foodborne infection, L. monocytogenes has to pass through the host gastrointestinal tract (GIT). In this study, we evaluated survival abilities of L. monocytogenes 10403S wild type (WT) and its isogenic mutants in alternative sigma (σ) factor genes (i.e., sigB, sigC, sigH, and sigL) under simulated gastric, duodenal, and bile fluids. Within 10min of exposures, only bile fluid was able to significantly reduce survival ability of L. monocytogenes WT by 2 logs CFU/ml. Loss of sigL showed the greatest bile resistance among 16 strains tested, p<0.0001, (i.e., WT, four single alternative σ factor mutants, six double mutants, four triple mutants, and one quadruple mutant). To further investigate the role of σL in bile response, RNA-seq was conducted to compare the transcriptional profiles among L. monocytogenes 10403S ΔBCH triple mutant (lacking sigB, sigC, and sigH genes; expressing housekeeping σA and σL) and ΔBCHL quadruple mutant (lacking all alternative sigma factor genes; expressing only σA) strains under BHI and 1% bile conditions. A total of 216 and 176 differentially expressed genes (DEGs) were identified in BHI and bile, respectively. We confirmed that mpt operon was shown to be strongly activated by σL. Interestingly, more than 80% of DEGs were found to be negatively regulated in the presence of σL. This includes PrfA regulon and its mediated genes (i.e., hly, hpt, inlB, clpP, clpE, groL, and inlC) which were downregulated in response to bile in the presence of σL. This result suggests the potential negative role of σL on bile survival, and the roles of σL and σB might be in a seesaw model prior to host cell invasion.

scholarly journals Regulatory Overlap and Functional Redundancy among Bacillus subtilis Extracytoplasmic Function σ Factors

2007 ◽  
Vol 189 (19) ◽  
pp. 6919-6927 ◽  
Author(s):  
Thorsten Mascher ◽  
Anna-Barbara Hachmann ◽  
John D. Helmann
Keyword(s):  
Mutant Strain ◽  
Wild Type Strain ◽  
Cell Envelope ◽  
Physiological Role ◽  
Polymyxin B ◽  
Triple Mutant ◽  
Σ Factor ◽  
Quadruple Mutant ◽  
Phenotype Microarrays ◽  
Increased Sensitivity

ABSTRACT Bacillus subtilis encodes seven extracytoplasmic function (ECF) σ factors that regulate partially overlapping regulons related to cell envelope homeostasis and antibiotic resistance. Here, we investigated their physiological role by constructing a mutant set of single, double, triple, and quadruple ECF σ factor deletions in the undomesticated B. subtilis strain NCIB3610. This mutant set was subsequently screened for defects in motility, multicellular differentiation, and sensitivity to more than 200 chemicals by using Phenotype MicroArrays. A quadruple mutant strain, harboring deletions of the sigV, sigY, sigZ, and ylaC gene, behaved indistinguishably from the wild-type strain, indicative of either regulatory redundancy or very specific functions of these four ECF σ factors. In contrast, a triple mutant, inactivated for the sigM, sigW, and sigX genes (but none of the corresponding double mutants), showed a biphasic growth behavior and a complete loss of multicellular differentiation, as judged by both colony formation and the inability to form a pellicle. This triple mutant also displayed a greatly increased sensitivity to detergents and several cell wall antibiotics including β-lactams, polymyxin B, and d-cycloserine. In several cases, these antibiotic-sensitive phenotypes are significantly enhanced in the triple mutant strain relative to strains lacking only one or two σ factors.

scholarly journals Alternative σ Factors Regulate Overlapping as Well as Distinct Stress Response and Metabolic Functions in Listeria monocytogenes under Stationary Phase Stress Condition

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 411
Author(s):  
Renato H. Orsi ◽  
Soraya Chaturongakul ◽  
Haley F. Oliver ◽  
Lalit Ponnala ◽  
Ahmed Gaballa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Listeria Monocytogenes ◽  
Stress Response ◽  
Stationary Phase ◽  
Metabolic Pathways ◽  
Regulatory Networks ◽  
Metabolic Functions ◽  
Σ Factor ◽  
Associated Functions ◽  
Isogenic Mutants

Listeria monocytogenes can regulate and fine-tune gene expression, to adapt to diverse stress conditions encountered during foodborne transmission. To further understand the contributions of alternative sigma (σ) factors to the regulation of L. monocytogenes gene expression, RNA-Seq was performed on L. monocytogenes strain 10403S and five isogenic mutants (four strains bearing in-frame null mutations in three out of four alternative σ factor genes, ΔCHL, ΔBHL, ΔBCL, and ΔBCH, and one strain bearing null mutations in all four genes, ΔBCHL), grown to stationary phase. Our data showed that 184, 35, 34, and 20 genes were positively regulated by σB, σL, σH, and σC (posterior probability > 0.9 and Fold Change (FC) > 5.0), respectively. Moreover, σB-dependent genes showed the highest FC (based on comparisons between the ΔCHL and the ΔBCHL strain), with 44 genes showing an FC > 100; only four σL-dependent, and no σH- or σC-dependent genes showed FC >100. While σB-regulated genes identified in this study are involved in stress-associated functions and metabolic pathways, σL appears to largely regulate genes involved in a few specific metabolic pathways, including positive regulation of operons encoding phosphoenolpyruvate (PEP)-dependent phosphotransferase systems (PTSs). Overall, our data show that (i) σB and σL directly and indirectly regulate genes involved in several energy metabolism-related functions; (ii) alternative σ factors are involved in complex regulatory networks and appear to have epistatic effects in stationary phase cells; and (iii) σB regulates multiple stress response pathways, while σL and σH positively regulate a smaller number of specific pathways.

A Geographical Study on Positive And Negative Role of Private Housing Cooperative Societies in Mysore City

2012 ◽  
Vol 3 (8) ◽  
pp. 55-58
Author(s):  
K.K. Somashekara K.K. Somashekara ◽  
◽  
B.N. Shivalingappa B.N. Shivalingappa
Keyword(s):  
Geographical Study ◽  
Housing Cooperative ◽  
Negative Role ◽  
Private Housing

scholarly journals RAD50 and RAD51 Define Two Pathways That Collaborate to Maintain Telomeres in the Absence of Telomerase

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Siyuan Le ◽  
J Kent Moore ◽  
James E Haber ◽  
Carol W Greider
Keyword(s):  
Cell Death ◽  
Telomere Length ◽  
Gene Conversion ◽  
De Novo ◽  
Dna Recombination ◽  
Telomere Maintenance ◽  
Triple Mutant ◽  
Yeast Telomerase ◽  
Telomere Lengthening

Abstract Telomere length is maintained by the de novo addition of telomere repeats by telomerase, yet recombination can elongate telomeres in the absence of telomerase. When the yeast telomerase RNA component, TLC1, is deleted, telomeres shorten and most cells die. However, gene conversion mediated by the RAD52 pathway allows telomere lengthening in rare survivor cells. To further investigate the role of recombination in telomere maintenance, we assayed telomere length and the ability to generate survivors in several isogenic DNA recombination mutants, including rad50, rad51, rad52, rad54, rad57, xrs2, and mre11. The rad51, rad52, rad54, and rad57 mutations increased the rate of cell death in the absence of TLC1. In contrast, although the rad50, xrs2, and mre11 strains initially had short telomeres, double mutants with tlc1 did not affect the rate of cell death, and survivors were generated at later times than tlc1 alone. While none of the double mutants of recombination genes and tlc1 (except rad52 tlc1) blocked the ability to generate survivors, a rad50 rad51 tlc1 triple mutant did not allow the generation of survivors. Thus RAD50 and RAD51 define two separate pathways that collaborate to allow cells to survive in the absence of telomerase.

scholarly journals Role of Branched-Chain Fatty Acids in pH Stress Tolerance in Listeria monocytogenes

2006 ◽  
Vol 73 (3) ◽  
pp. 997-1001 ◽  
Author(s):  
Efstathios S. Giotis ◽  
David A. McDowell ◽  
Ian S. Blair ◽  
Brian J. Wilkinson
Keyword(s):  
Fatty Acids ◽  
Listeria Monocytogenes ◽  
Stress Tolerance ◽  
Ph Sensitive ◽  
Branched Chain Fatty Acids ◽  
Alkaline Conditions ◽  
Branched Chain ◽  
Ph Adaptation ◽  
Chain Fatty Acids

ABSTRACT In alkaline conditions, Listeria monocytogenes cells develop higher proportions of branched-chain fatty acids (FAs), including more anteiso forms. In acid conditions, the opposite occurs. Reduced growth of pH-sensitive mutants at adverse pH (5.0/9.0) was alleviated by the addition of 2-methylbutyrate (an anteiso-FA precursor), suggesting that anteiso-FAs are important in adaptation to adverse pH. The balance between anteiso- and iso-FAs may be more important than changes in the amounts and/or degrees of saturation of FAs in pH adaptation.

The influence of discourse context on children's provision of auxiliary BE

2008 ◽  
Vol 35 (1) ◽  
pp. 129-158 ◽  
Author(s):  
ANNA L. THEAKSTON ◽  
ELENA V. M. LIEVEN
Keyword(s):  
Language Acquisition ◽  
Word Order ◽  
Current Paper ◽  
Discourse Context ◽  
Linguistic Representations ◽  
Prior Use ◽  
Single Child ◽  
Pass Through ◽  
Children's Speech

ABSTRACTChildren pass through a stage in development when they produce utterances that contain auxiliary BE (he's playing) and utterances where auxiliary BE is omitted (he playing). One explanation that has been put forward to explain this phenomenon is the presence of questions in the input that model S-V word order (Theakston, Lieven & Tomasello, 2003). The current paper reports two studies that investigate the role of the input in children's use and non-use of auxiliary BE in declaratives. In Study 1, 96 children aged from 2 ; 5 to 2 ; 10 were exposed to known and novel verbs modelled in questions only or declaratives only. In Study 2, naturalistic data from a dense database from a single child between the ages of 2 ; 8 to 3 ; 2 were examined to investigate the influence of (1) declaratives and questions in the input in prior discourse, and (2) the child's immediately previous use of declaratives where auxiliary BE was produced or omitted, on his subsequent use or non-use of auxiliary BE. The results show that in both the experimental and naturalistic contexts, the presence of questions in the input resulted in lower levels of auxiliary provision in the children's speech than in utterances following declaratives in the input. In addition, the children's prior use or non-use of auxiliary BE influenced subsequent use. The findings are discussed in the context of usage-based theories of language acquisition and the role of the language children hear in their developing linguistic representations.

Leukocyte kinetics in the human lung: role of exercise and catecholamines

1984 ◽  
Vol 57 (3) ◽  
pp. 711-719 ◽  
Author(s):  
A. L. Muir ◽  
M. Cruz ◽  
B. A. Martin ◽  
H. Thommasen ◽  
A. Belzberg ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Peripheral Blood ◽  
Human Lung ◽  
Work Load ◽  
Low Flow ◽  
Epinephrine Infusion ◽  
First Pass ◽  
Pass Through

In six normal supine subjects epinephrine infusion produced a greater leukocytosis with smaller changes in heart rate and blood pressure than did norepinephrine or isoproterenol. Upright exercise in those subjects produced a greater leukocytosis than supine exercise at the same work load. To determine the lung's participation in these events, indium-labeled neutrophils (PMN) were given to four of the subjects. We found that 20–25% were retained in the first pass through the lung when compared with technetium-labeled erythrocytes. The number of labeled PMN in the lung gradually decreased and the number in the spleen and the liver increased. Exercise and catecholamine infusion caused an acceleration in the release of labeled cells from the lung, an increase in both labeled and unlabeled cells in the peripheral blood, and an increase in the number of labeled cells in the liver and spleen. This suggests that increased perfusion of low-flow areas in the lung may contribute to the increased leukocytosis seen in association with both exercise and catecholamine infusion.

Sign in / Sign up

Export Citation Format

Share Document