scholarly journals Competition and Resilience between Founder and Introduced Bacteria in the Caenorhabditis elegans Gut

2011 ◽  
Vol 80 (3) ◽  
pp. 1288-1299 ◽  
Author(s):  
Cynthia Portal-Celhay ◽  
Martin J. Blaser
Keyword(s):  
Caenorhabditis Elegans ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
C Elegans ◽  
Serovar Typhimurium ◽  
Colonization Factors

The microbial communities that reside within the intestinal tract in vertebrates are complex and dynamic. In this report, we establish the utility ofCaenorhabditis elegansas a model system for identifying the factors that contribute to bacterial persistence and for host control of gut luminal populations. We found that for N2 worms grown on mixed lawns of bacteria,Salmonella entericaserovar Typhimurium substantially outcompetedEscherichia coli, even whenE. coliwas initially present at 100-fold-higher concentrations. To address whether innate immunity affects the competition, thedaf-2anddaf-16mutants were studied; their total gut bacterial levels reflect overall capacity for colonization, butSalmonellaoutcompetedE. colito an extent similar to wild-type worms. To address the role of virulence properties,SalmonellaΔspi-1Δspi-2was used to compete withE. coli. The net differential was significantly less than that for wild-typeSalmonella; thus,spi-1 spi-2encodesC. eleganscolonization factors. AnE. colistrain with repeatedin vivopassage had an enhanced ability to compete against anin vitro-passedE. colistrain and againstSalmonella. Our data provide evidence of active competition for colonization niches in theC. elegansgut, as determined by bacterial factors and subject toin vivoselection.

scholarly journals Arabidopsis Disulfide Reductase, Trx-h2, Functions as an RNA Chaperone under Cold Stress

2021 ◽  
Vol 11 (15) ◽  
pp. 6865
Author(s):  
Eun Seon Lee ◽  
Joung Hun Park ◽  
Seong Dong Wi ◽  
Ho Byoung Chae ◽  
Seol Ki Paeng ◽  
...  
Keyword(s):  
Cold Stress ◽  
Wild Type ◽  
Rna Chaperone ◽  
E Coli ◽  
Cold Sensitive ◽  
Thioredoxin H ◽  
Functional Rnas

The thioredoxin-h (Trx-h) family of Arabidopsis thaliana comprises cytosolic disulfide reductases. However, the physiological function of Trx-h2, which contains an additional 19 amino acids at its N-terminus, remains unclear. In this study, we investigated the molecular function of Trx-h2 both in vitro and in vivo and found that Arabidopsis Trx-h2 overexpression (Trx-h2OE) lines showed significantly longer roots than wild-type plants under cold stress. Therefore, we further investigated the role of Trx-h2 under cold stress. Our results revealed that Trx-h2 functions as an RNA chaperone by melting misfolded and non-functional RNAs, and by facilitating their correct folding into active forms with native conformation. We showed that Trx-h2 binds to and efficiently melts nucleic acids (ssDNA, dsDNA, and RNA), and facilitates the export of mRNAs from the nucleus to the cytoplasm under cold stress. Moreover, overexpression of Trx-h2 increased the survival rate of the cold-sensitive E. coli BX04 cells under low temperature. Thus, our data show that Trx-h2 performs function as an RNA chaperone under cold stress, thus increasing plant cold tolerance.

scholarly journals Fimbria-Encoding GeneyadCHas a Pleiotropic Effect on Several Biological Characteristics and Plays a Role in Avian Pathogenic Escherichia coli Pathogenicity

2015 ◽  
Vol 84 (1) ◽  
pp. 187-193 ◽  
Author(s):  
Renu Verma ◽  
Thaís Cabrera Galvão Rojas ◽  
Renato Pariz Maluta ◽  
Janaína Luisa Leite ◽  
Livia Pilatti Mendes da Silva ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Soft Agar ◽  
Pleiotropic Effect ◽  
Biological Characteristics ◽  
Wild Type ◽  
Content Type ◽  
Pathogenic Escherichia Coli

The extraintestinal pathogen termed avian pathogenicEscherichia coli(APEC) is known to cause colibacillosis in chickens. The molecular basis of APEC pathogenesis is not fully elucidated yet. In this work, we deleted a component of the Yad gene cluster (yadC) in order to understand the role of Yad in the pathogenicity of the APEC strain SCI-07.In vitro, the transcription level ofyadCwas upregulated at 41°C and downregulated at 22°C. TheyadCexpressionin vivowas more pronounced in lungs than in spleen, suggesting a role in the early steps of the infection. Chicks infected with the wild-type and mutant strains presented, respectively, 80% and 50% mortality rates. The ΔyadCstrain presented a slightly decreased ability to adhere to HeLa cells with or without thed-mannose analog compared with the wild type. Real-time PCR (RT-PCR) assays showed thatfimHwas downregulated (P< 0.05) andcsgAandecpAwere slightly upregulated in the mutant strain, showing thatyadCmodulates expression of other fimbriae. Bacterial internalization studies showed that the ΔyadCstrain had a lower number of intracellular bacteria recovered from Hep-2 cells and HD11 cells than the wild-type strain (P< 0.05). Motility assays in soft agar demonstrated that the ΔyadCstrain was less motile than the wild type (P< 0.01). Curiously, flagellum-associated genes were not dramatically downregulated in the ΔyadCstrain. Taken together, the results show that the fimbrial adhesin Yad contributes to the pathogenicity and modulates different biological characteristics of the APEC strain SCI-07.

scholarly journals Effect of Inactivation of degS on Salmonella enterica Serovar Typhimurium In Vitro and In Vivo

2005 ◽  
Vol 73 (1) ◽  
pp. 459-463 ◽  
Author(s):  
Gary Rowley ◽  
Andrew Stevenson ◽  
Jan Kormanec ◽  
Mark Roberts
Keyword(s):  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Wild Type ◽  
Alternative Pathways ◽  
E Coli ◽  
Mammalian Tissues ◽  
Serovar Typhimurium

ABSTRACT The alternative sigma factor (RpoE σE) enables Salmonella enterica serovar Typhimurium to adapt to stressful conditions, such as oxidative stress, nutrient deprivation, and growth in mammalian tissues. Infection of mice by Salmonella serovar Typhimurium also requires σE. In Escherichia coli, activation of the σE pathway is dependent on proteolysis of the anti-sigma factor RseA and is initiated by DegS. DegS is also important in order for E. coli to cause extraintestinal infection in mice. We constructed a degS mutant of the serovar Typhimurium strain SL1344 and compared its behavior in vitro and in vivo with those of its wild-type (WT) parent and an isogenic rpoE mutant. Unlike E. coli degS strains, the Salmonella serovar Typhimurium degS strain grew as well as the WT strain at 42°C. The degS mutant survived very poorly in murine macrophages in vitro and was highly attenuated compared with the WT strain for both the oral and parenteral routes of infection in mice. However, the degS mutant was not as attenuated as the serovar Typhimurium rpoE mutant: 100- to 1,000-fold more degS bacteria than rpoE bacteria were present in the livers and spleens of mice 24 h after intraperitoneal challenge. In most assays, the rpoE mutant was more severely affected than the degS mutant and a σE-dependent reporter gene was more active in the degS mutant than the rpoE strain. These findings indicate that degS is important for activation of the σE pathway in serovar Typhimurium but that alternative pathways for σE activation probably exist.

scholarly journals Role of RpoS in the Virulence of Citrobacter rodentium

2008 ◽  
Vol 77 (1) ◽  
pp. 501-507 ◽  
Author(s):  
Tao Dong ◽  
Brian K. Coombes ◽  
Herb E. Schellhorn
Keyword(s):  
Pathogenicity Island ◽  
Competitive Growth ◽  
Citrobacter Rodentium ◽  
Wild Type ◽  
E Coli ◽  
Mouse Colon ◽  
Expression Of Genes

ABSTRACT Citrobacter rodentium is a mouse enteropathogen that is closely related to Escherichia coli and causes severe colonic hyperplasia and bloody diarrhea. C. rodentium infection requires expression of genes of the locus of enterocyte effacement (LEE) pathogenicity island, which simulates infection by enteropathogenic E. coli and enterohemorrhagic E. coli in the human intestine, providing an effective model for studying enteropathogenesis. In this study we investigated the role of RpoS, the stationary phase sigma factor, in virulence in C. rodentium. Sequence analysis showed that the rpoS gene is highly conserved in C. rodentium and E. coli, exhibiting 92% identity. RpoS was critical for survival under heat shock conditions and during exposure to H2O2 and positively regulated the expression of catalase KatE (HPII). The development of the RDAR (red dry and rough) morphotype, an important virulence trait in E. coli, was also mediated by RpoS in C. rodentium. Unlike E. coli, C. rodentium grew well in the mouse colon, and the wild-type strain colonized significantly better than rpoS mutants. However, a mutation in rpoS conferred a competitive growth advantage over the wild type both in vitro in Luria-Bertani medium and in vivo in the mouse colon. Survival analysis showed that the virulence of an rpoS mutant was attenuated. The expression of genes on the LEE pathogenicity island, which are essential for colonization and virulence, was reduced in the rpoS mutant. In conclusion, RpoS is important for the stress response and is required for full virulence in C. rodentium.

scholarly journals Exoribonuclease and Endoribonuclease Activities of RNase BN/RNase Z both Function in Vivo

2012 ◽  
Vol 287 (42) ◽  
pp. 35747-35755 ◽  
Author(s):  
Tanmay Dutta ◽  
Arun Malhotra ◽  
Murray P. Deutscher
Keyword(s):  
Potential Role ◽  
Wild Type ◽  
X Ray ◽  
E Coli ◽  
Phage T4 ◽  
A Cell ◽  
Rnase Z

Escherichia coli RNase BN, a member of the RNase Z family of endoribonucleases, differs from other family members in that it also can act as an exoribonuclease in vitro. Here, we examine whether this activity of RNase BN also functions in vivo. Comparison of the x-ray structure of RNase BN with that of Bacillus subtilis RNase Z, which lacks exoribonuclease activity, revealed that RNase BN has a narrower and more rigid channel downstream of the catalytic site. We hypothesized that this difference in the putative RNA exit channel might be responsible for the acquisition of exoribonuclease activity by RNase BN. Accordingly, we generated several mutant RNase BN proteins in which residues within a loop in this channel were converted to the corresponding residues present in B. subtilis RNase Z, thus widening the channel and increasing its flexibility. The resulting mutant RNase BN proteins had reduced or were essentially devoid of exoribonuclease activity in vitro. Substitution of one mutant rbn gene (P142G) for wild type rbn in the E. coli chromosome revealed that the exoribonuclease activity of RNase BN is not required for maturation of phage T4 tRNA precursors, a known specific function of this RNase. On the other hand, removal of the exoribonuclease activity of RNase BN in a cell lacking other processing RNases leads to slower growth and affects maturation of multiple tRNA precursors. These findings help explain how RNase BN can act as both an exo- and an endoribonuclease and also demonstrate that its exoribonuclease activity is capable of functioning in vivo, thus widening the potential role of this enzyme in E. coli.

scholarly journals Comparative phytochemical analysis of Phlogacanthus thyrsiflorus Nees: Implications on attenuation of pro-oxidants and pathogen virulence in Caenorhabditis elegans model system

2017 ◽  
Vol 10 (5) ◽  
pp. 361
Author(s):  
Kitlangki Suchiang ◽  
Nitasha H Kayde
Keyword(s):  
Oxidative Stress ◽  
Free Radicals ◽  
Free Radical ◽  
Caenorhabditis Elegans ◽  
Model System ◽  
Wild Type ◽  
C Elegans ◽  
Mutant Strains

Background: Phlogacanthus thyrsiflorus Nees (P. thyrsiflorus) of Acanthaceae family is endogenous to sub-tropical Himalayas. It has been reported to be used traditionally in Jaintia tribe of Meghalaya, India for treatment of many ailments.Objectives: The aim was to detect the active compounds present in the leaves for evaluation of in vitro free radicals scavenging potentials. Leaves protective actions in vivo will be investigated using Caenorhabditis elegans (C. elegans) model system utilizing wild type and mutant strains and the phenomena of host-pathogens interactions.Materials and methods: Gas chromatography/ Mass spectrometry (GC/MS) was used for detection of different compounds present. The versatility of leaf extracts to scavenge different free radicals generated in vitro was assessed with different in vitro methods. Survival analysis of wild type and mutant strains C. elegans under enhanced pro-oxidants exposure was investigated in vivo. Fast killing assay was also performed to study the extracts modulatory activity on host C. elegans survival under pathogen Pseudomonas aeruginosa infection.Results:  Forty compounds were detected in methanolic fraction of the extract with variable percentages. Both aqueous and methanol extract possessed remarkable, versatile free radical scavenging activity irrespective of the types of free radical generated. The in vivo experiments are in compliance, with observable increased survival ability percentage of C. elegans under intense exogenous oxidative stress and pathogen infection.Conclusion: Our findings enlightened the different compounds present with versatility of P. thyrsiflorus in tackling different free radicals generated both in vitro and in vivo that highly support for its candidature as a good antioxidant source. Our findings may justify the historical relevance of this plant in herbal remedies that could form the basis for inquiry of new active principles.Keywords: Free radicals, Oxidative stress, Caenorhabditis elegans, Phlogacanthus thyrsiflorus, Phytochemicals

scholarly journals Role of Mouse Peptidoglycan Recognition Protein PGLYRP2 in the Innate Immune Response to Salmonella enterica Serovar Typhimurium InfectionIn Vivo

2012 ◽  
Vol 80 (8) ◽  
pp. 2645-2654 ◽  
Author(s):  
Jooeun Lee ◽  
Kaoru Geddes ◽  
Catherine Streutker ◽  
Dana J. Philpott ◽  
Stephen E. Girardin
Keyword(s):  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Intraepithelial Lymphocytes ◽  
Innate Immune ◽  
Th17 Response ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTPeptidoglycan recognition proteins (PGRPs) are a family of innate pattern recognition molecules that bind bacterial peptidoglycan. While the role of PGRPs inDrosophilainnate immunity has been extensively studied, how the four mammalian PGRP proteins (PGLYRP1 to PGLYRP4) contribute to host defense against bacterial pathogensin vivoremains poorly understood. PGLYRP1, PGLYRP3, and PGLYRP4 are directly bactericidalin vitro, whereas PGLYRP2 is anN-acetylmuramyl-l-alanine amidase that cleaves peptidoglycan between the sugar backbone and the peptide stem. Because PGLYRP2 cleaves muramyl peptides detected by host peptidoglycan sensors Nod1 and Nod2, we speculated that PGLYRP2 may act as a modifier of Nod1/Nod2-dependent innate immune responses. We investigated the role of PGLYRP2 inSalmonella entericaserovar Typhimurium-induced colitis, which is regulated by Nod1/Nod2 through the induction of an early Th17 response. PGLYRP2 did not contribute to expression of Th17-associated cytokines, interleukin-22 (IL-22)-dependent antimicrobial proteins, or inflammatory cytokines. However, we found thatPglyrp2-deficient mice displayed significantly enhanced inflammation in the cecum at 72 h postinfection, reflected by increased polymorphonuclear leukocyte (PMN) infiltration and goblet cell depletion.Pglyrp2expression was also induced in the cecum ofSalmonella-infected mice, and expression of green fluorescent protein under control of thePglyrp2promoter was increased in discrete populations of intraepithelial lymphocytes. Lastly,Nod2−/−Pglyrp2−/−mice displayed increased susceptibility to infection at 24 h postinfection compared toPglyrp2−/−mice, which correlated with increased PMN infiltration and submucosal edema. Thus, PGLYRP2 plays a protective rolein vivoin the control ofS. Typhimurium infection through a Nod1/Nod2-independent mechanism.

scholarly journals The Homolog of the Gene bstA of the BTP1 Phage from Salmonella enterica Serovar Typhimurium ST313 Is an Antivirulence Gene in Salmonella enterica Serovar Dublin

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Ana Herrero-Fresno ◽  
Irene Cartas Espinel ◽  
Malene Roed Spiegelhauer ◽  
Priscila Regina Guerra ◽  
Karsten Wiber Andersen ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Luria Bertani ◽  
Wild Type ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Cattle Blood

ABSTRACTIn a previous study, a novel virulence gene,bstA, identified in aSalmonella entericaserovar Typhimurium sequence type 313 (ST313) strain was found to be conserved in all publishedSalmonella entericaserovar Dublin genomes. In order to analyze the role of this gene in the host-pathogen interaction inS. Dublin, a mutant where this gene was deleted (S. Dublin ΔbstA) and a mutant which was further genetically complemented withbstA(S. Dublin 3246-C) were constructed and tested in models ofin vitroandin vivoinfection as well as during growth competition assays in M9 medium, Luria-Bertani broth, and cattle blood. In contrast to the results obtained for a strain ofS. Typhimurium ST313, the lack ofbstAwas found to be associated with increased virulence inS. Dublin. Thus,S. Dublin ΔbstAshowed higher levels of uptake than the wild-type strain during infection of mouse and cattle macrophages and higher net replication within human THP-1 cells. Furthermore, during mouse infections,S. Dublin ΔbstAwas more virulent than the wild type following a single intraperitoneal infection and showed an increased competitive index during competitive infection assays. Deletion ofbstAdid not affect either the amount of cytokines released by THP-1 macrophages or the cytotoxicity toward these cells. The histology of the livers and spleens of mice infected with the wild-type strain and theS. Dublin ΔbstAmutant revealed similar levels of inflammation between the two groups. The gene was not important for adherence to or invasion of human epithelial cells and did not influence bacterial growth in rich medium, minimal medium, or cattle blood. In conclusion, a lack ofbstAaffects the pathogenicity ofS. Dublin by decreasing its virulence. Therefore, it might be regarded as an antivirulence gene in this serovar.

scholarly journals Adherence of Escherichia coli O157:H7 Mutants In Vitro and in Ligated Pig Intestines

2009 ◽  
Vol 75 (15) ◽  
pp. 4975-4983 ◽  
Author(s):  
Xianhua Yin ◽  
James R. Chambers ◽  
Roger Wheatcroft ◽  
Roger P. Johnson ◽  
Jing Zhu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Genes ◽  
Cultured Cells ◽  
Escherichia Coli O157 ◽  
Wild Type ◽  
Wild Type Level ◽  
E Coli

ABSTRACT There are contradictory literature reports on the role of verotoxin (VT) in adherence of enterohemorrhagic Escherichia coli O157:H7 (O157 EHEC) to intestinal epithelium. There are reports that putative virulence genes of O island 7 (OI-7), OI-15, and OI-48 of this pathogen may also affect adherence in vitro. Therefore, mutants of vt2 and segments of OI-7 and genes aidA 15 (gene from OI-15) and aidA 48 (gene from OI-48) were generated and evaluated for adherence in vitro to cultured human HEp-2 and porcine jejunal epithelial (IPEC-J2) cells and in vivo to enterocytes in pig ileal loops. VT2-negative mutants showed significant decreases in adherence to both HEp-2 and IPEC-J2 cells and to enterocytes in pig ileal loops; complementation only partially restored VT2 production but fully restored the adherence to the wild-type level on cultured cells. Deletion of OI-7 and aidA 48 had no effect on adherence, whereas deletion of aidA 15 resulted in a significant decrease in adherence in pig ileal loops but not to the cultured cells. This investigation supports the findings that VT2 plays a role in adherence, shows that results obtained in adherence of E. coli O157:H7 in vivo may differ from those obtained in vitro, and identified AIDA-15 as having a role in adherence of E. coli O157:H7.

scholarly journals Promoters of the dhs-21 gene encoding dicarbonyl/l-xylulose reductase in Caenorhabditis elegans

2018 ◽  
Vol 15 (2) ◽  
pp. 359-365
Author(s):  
Lê Thọ Sơn ◽  
Joohong Ahnn ◽  
Jeong Hoon Cho ◽  
Nguyễn Huy Hoàng
Keyword(s):  
Caenorhabditis Elegans ◽  
Model Organism ◽  
Biological Research ◽  
Loss Of Function ◽  
Wild Type ◽  
C Elegans ◽  
Larval Stages ◽  
Vital Functions

Dicarbonyl/L-xylulose (DCXR) was identified as a dehydrogenase. This type of enzyme was presented in various forms of lives including bacteria, fungi, plants and animals. Generally, it converts L-xylulose to xylitol in the presence of either cofactor NADH or NADPH in vitro. Previous studies reported the biochemistry properties and crystal structure but largely uncovered biological roles of DCXRs. It was impossible to dissect the functions in mice or human cells that had many DCXR homologs in their genomes. Interestingly, the wild-type Caenorhabditis elegans, a well-known model organism in biological research, has only nuclear genomic dhs-21 that encodes a unique homologous DCXR. Thus Ce.dhs-21 and the host C. elegans were relevant for investigation of the physiologically-vital functions of the DCXR. This research aimed to the expression of dhs-21 in vivo. We defined three promoters , manipulated three relative reporter-constructs that conjugated the dhs-21 gene and Green Flouresent Protein (known as GFP) one. The construct vectors were transferred into wild-type C. elegans N2 and as well as the hermaphroditic loss of function dhs-21(jh129) by microinjection. In the results, we found that the expression pattern of dhs-21 under the only p2-promoter construct was stable and similar to immunogold Electric Microscopy (EM) images. The dhs-21 gene was expressed in both sexes of at all larval stages till the deaths of worms. DHS-21 was expressed in the cytosol of the intestinal, gonad sheath and uterous seam cell (utse).

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