scholarly journals Effect of Trehalose and Trehalose Transport on the Tolerance ofClostridium perfringensto Environmental Stress in a Wild Type Strain and Its Fluoroquinolone-Resistant Mutant

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Miseon Park ◽  
Wilfrid J. Mitchell ◽  
Fatemeh Rafii
Keyword(s):  
Environmental Stress ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Defined Medium ◽  
Low Ph ◽  
Bacterial Cells ◽  
Chemically Defined Medium ◽  
Wild Type ◽  
Qrt Pcr

Trehalose has been shown to protect bacterial cells from environmental stress. Its uptake and osmoprotective effect inClostridium perfringenswere investigated by comparing wild typeC. perfringensATCC 13124 with a fluoroquinolone- (gatifloxacin-) resistant mutant. In a chemically defined medium, trehalose and sucrose supported the growth of the wild type but not that of the mutant. Microarray data and qRT-PCR showed that putative genes for the phosphorylation and transport of sucrose and trehalose (via phosphoenolpyruvate-dependent phosphotransferase systems, PTS) and some regulatory genes were downregulated in the mutant. The wild type had greater tolerance than the mutant to salts and low pH; trehalose and sucrose further enhanced the osmotolerance of the wild type to NaCl. Expression of the trehalose-specific PTS was lower in the fluoroquinolone-resistant mutant. Protection ofC. perfringensfrom environmental stress could therefore be correlated with the ability to take up trehalose.

Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain

2015 ◽  
Vol 71 (4) ◽  
pp. 860-872 ◽  
Author(s):  
Elena Bañares-España ◽  
María del Mar Fernández-Arjona ◽  
María Jesús García-Sánchez ◽  
Miguel Hernández-López ◽  
Andreas Reul ◽  
...  
Keyword(s):  
Comparative Study ◽  
Microcystis Aeruginosa ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Photosynthetic Performance ◽  
Wild Type

scholarly journals A heat shock-resistant mutant of Saccharomyces cerevisiae shows constitutive synthesis of two heat shock proteins and altered growth.

1984 ◽  
Vol 99 (4) ◽  
pp. 1441-1450 ◽  
Author(s):  
H Iida ◽  
I Yahara
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Type Strain ◽  
Wild Type Strain ◽  
Growth Control ◽  
Protein S ◽  
Resistant Mutant ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Sulfur Starvation

A heat shock-resistant mutant of the budding yeast Saccharomyces cerevisiae was isolated at the mutation frequency of 10(-7) from a culture treated with ethyl methane sulfonate. Cells of the mutant are approximately 1,000-fold more resistant to lethal heat shock than those of the parental strain. Tetrad analysis indicates that phenotypes revealed by this mutant segregated together in the ratio 2+:2- from heterozygotes constructed with the wild-type strain of the opposite mating type, and are, therefore, attributed to a single nuclear mutation. The mutated gene in the mutant was herein designated hsr1 (heat shock response). The hsr1 allele is recessive to the HSR1+ allele of the wild-type strain. Exponentially growing cells of hsr1 mutant were found to constitutively synthesize six proteins that are not synthesized or are synthesized at reduced rates in HSR1+ cells unless appropriately induced. These proteins include one hsp/G0-protein (hsp48A), one hsp (hsp48B), and two G0-proteins (p73, p56). Heterozygous diploid (hsr1/HSR1+) cells do not synthesize the proteins constitutively induced in hsr1 cells, which suggests that the product of the HSR1 gene might negatively regulate the synthesis of these proteins. The hsr1 mutation also led to altered growth of the mutant cells. The mutation elongated the duration of G1 period in the cell cycle and affected both growth arrest by sulfur starvation and growth recovery from it. We discuss the problem of which protein(s) among those constitutively expressed in growing cells of the hsr1 mutant is responsible for heat shock resistance and alterations in the growth control.

scholarly journals Helicobacter pyloriOuter Membrane Protein 18 (Hp1125) Is Involved in Persistent Colonization by Evading Interferon-γSignaling

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yuqun Shan ◽  
Xingxiao Lu ◽  
Yingnan Han ◽  
Xinpeng Li ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Immune Surveillance ◽  
Survival Rates ◽  
Wild Type ◽  
Qrt Pcr ◽  
H Pylori ◽  
Host Immune Surveillance

Outer membrane proteins (OMPs) can induce an immune response. Omp18 (HP1125) ofH. pyloriis a powerful antigen that can induce significant interferon-γ(IFN-γ) levels. Previous studies have suggested that IFN-γplays an important role inH. pyloriclearance. However,H. pylorihas multiple mechanisms to avoid host immune surveillance for persistent colonization. We generated anomp18mutant (H. pylori26695 andH. pyloriSS1) strain to examine whether Omp18 interacts with IFN-γand is involved inH. pyloricolonization. qRT-PCR revealed that IFN-γinduced Omp18 expression. qRT-PCR and western blot analysis revealed reduced expressions of virulence factors CagA and NapA inH. pylori26695 with IFN-γtreatment, but they were induced in the Δomp18strain. In C57BL/6 mice infected withH. pyloriSS1 and the Δomp18strain, the Δomp18strain conferred defective colonization and activated a stronger inflammatory response. Signal transducer phosphorylation and transcription 1 (STAT1) activator was downregulated by the wild-type strain but not the Δomp18strain in IFN-γ-treated macrophages. Furthermore, Δomp18strain survival rates were poor in macrophages compared to the wild-type strain. We concluded thatH. pyloriOmp18 has an important function influencing IFN-γ-mediated immune response to participate in persistent colonization.

Pathogenic potential of a collagenase gene fromAeromonas veronii

2008 ◽  
Vol 54 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hyun-Ja Han ◽  
Tatsuo Taki ◽  
Hidehiro Kondo ◽  
Ikuo Hirono ◽  
Takashi Aoki
Keyword(s):  
Mutant Strain ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Collagenolytic Activity ◽  
Bacterial Cells ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Collagenase Gene

The role of collagenase as a mechanism of bacterial pathogenicity in some pathogenic bacteria has been reported. The information on the role of collagenase in Aeromonas spp. pathogenesis is scant. In the present study, a mutant Aeromonas veronii RY001 that is deficient in the putative collagenase gene acg was constructed and compared with the wild-type strain for virulence factors. Bacterial cells and cell-free extracellular products of the mutant had significantly less collagenolytic activity, but there were not significant differences in caseinolytic, gelatinolytic, and elastolytic activities. Adhesion and invasion abilities of the mutant strain on epithelioma papillosum of carp cells was only 56% of that of the wild-type strain, and the cytotoxicity of the mutant strain to epithelioma papillosum of carp cells was only 42% of that of the wild-type strain. The LD50values of the wild-type strain were determined as 1.6 × 106and 3.5 × 105cfu in goldfish and mice, respectively, whereas the mutant RY001 strain showed slightly higher values (i.e., 2.8 × 106and 1.4 × 106cfu in goldfish and mice, respectively). These results indicated the involvement of the collagenase gene in the pathogenesis of A. veronii.

scholarly journals Inhibition of Phagocytosis by Haemophilus ducreyi Requires Expression of the LspA1 and LspA2 Proteins

2003 ◽  
Vol 71 (10) ◽  
pp. 5994-6003 ◽  
Author(s):  
Merja Vakevainen ◽  
Steven Greenberg ◽  
Eric J. Hansen
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Rabbit Model ◽  
Inhibitory Effect ◽  
Haemophilus Ducreyi ◽  
Bacterial Cells ◽  
Wild Type ◽  
Temperature Dependent ◽  
Live Bacterial Cells

ABSTRACT Haemophilus ducreyi previously has been shown to inhibit the phagocytosis of both secondary targets and itself by certain cells in vitro. Wild-type H. ducreyi strain 35000HP contains two genes, lspA1 and lspA2, whose encoded protein products are predicted to be 456 and 543 kDa, respectively. An isogenic mutant of H. ducreyi 35000HP with inactivated lspA1 and lspA2 genes has been shown to exhibit substantially decreased virulence in the temperature-dependent rabbit model for chancroid. This lspA1 lspA2 mutant was tested for its ability to inhibit phagocytosis of immunoglobulin G-opsonized particles by differentiated HL-60 and U-937 cells and by J774A.1 cells. The wild-type strain H. ducreyi 35000HP readily inhibited phagocytosis, whereas the lspA1 lspA2 mutant was unable to inhibit phagocytosis. Similarly, the wild-type strain was resistant to phagocytosis, whereas the lspA1 lspA2 mutant was readily engulfed by phagocytes. This inhibitory effect of wild-type H. ducreyi on phagocytic activity was primarily associated with live bacterial cells but could also be found, under certain conditions, in concentrated H. ducreyi culture supernatant fluids that lacked detectable outer membrane fragments. Both the wild-type strain and the lspA1 lspA2 mutant attached to phagocytes at similar levels. These results indicate that the LspA1 and LspA2 proteins of H. ducreyi are involved, directly or indirectly, in the antiphagocytic activity of this pathogen, and they provide a possible explanation for the greatly reduced virulence of the lspA1 lspA2 mutant.

scholarly journals Controlling the hypermutation: Exploitation of the MutS protein in Pseudomonas aeruginosa

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Yue Yuan On ◽  
Martin Welch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Inducible Promoter ◽  
Wild Type ◽  
Cdna Analysis ◽  
In The Wild ◽  
Mismatch Recognition ◽  
Muts Gene

Pseudomonas aeruginosa infections commonly develop in individuals with cystic fibrosis (CF), and its adaptation in such an unfavourable condition is always found to be related to hypermutation. In fact, most of the hypermutation is due to the defects in mutS gene which involves in the mismatch repair mechanism, causing the acceleration of mutation rate and adaptive evolution. In order to rheostatically express the MutS protein and achieve “hypomutation” (in which the rate of mutation is lower than that of wild type strain), an exogenous mutS gene with rhamnose-inducible promoter was cloned into MPAO1 mutS::Tn mutant strain. Present findings demonstrate that this system is tightly-controlled and stable, with less rifampicin-resistant mutant frequency and more fluorescence intensity from a GFP-tagged MutS expressing cells were observed when the concentration of the inducer increases. Interestingly, the results from Western blot analysis show that less MutS protein is required to suppress hypermutation in the wild type strain, as compared to our construct that behaves similar to the wild type but obviously needs more MutS expression to achieve such state. This indicates that the exogenous MutS might be lacking of other important protein to work efficiently in mismatch recognition. Therefore, based on our cDNA analysis, we found that fdxA gene next to the mutS gene is in the same operon, which could suggest that they might be functionally related in the DNA repair machinery.

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