Publications

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biological properties and chemical composition of jatropha neopauciflora pax.ethnopharmacological relevance. jatropha neopauciflora (pax) is an endemic species of the tehuacan- cuicatlan valley, mexico. this species has long been used as a remedy to alleviate illnesses of bacterial, fungal and viral origin. aim of the study. experimentally test the traditional use of jatropha neopauciflora in mexican traditional medicine.201728331913
vope, a vibrio cholerae type iii effector, attenuates the activation of cwi-mapk pathway in yeast model system.vope, a mitochondrial targeting t3ss effector protein of vibrio cholerae, perturbs innate immunity by modulating mitochondrial dynamics. in the current study, ectopic expression of vope was found to be toxic in a yeast model system and toxicity was further aggravated in the presence of various stressors. interestingly, a vope variant lacking predicted mitochondrial targeting sequence (mts) also exhibited partial lethality in the yeast system. with the aid of yeast genetic tools and different str ...201728373966
rapid dipstick detection of vibrio cholerae in household stored and municipal water in dhaka, bangladesh: chobi7 trial.in urban dhaka, bangladesh, 30% of source water samples collected from the households of patients with cholera had detectable vibrio cholerae. these findings indicate an urgent need for a public health intervention for this population. the crystal vc(®) dipstick test is a rapid method for detecting v. cholerae in stool and water. however, to date no study has investigated the use of the rapid dipstick test for household surveillance of stored drinking water.201727754582
genome-wide biases in the rate and molecular spectrum of spontaneous mutations in vibrio cholerae and vibrio fischeri.the vast diversity in nucleotide composition and architecture among bacterial genomes may be partly explained by inherent biases in the rates and spectra of spontaneous mutations. bacterial genomes with multiple chromosomes are relatively unusual but some are relevant to human health, none more so than the causative agent of cholera, vibrio cholerae here, we present the genome-wide mutation spectra in wild-type and mismatch repair (mmr) defective backgrounds of two vibrio species, the low-%gc sq ...201727744412
characterization of vibrio cholerae isolates from 1976 to 2013 in shandong province, china.cholera continues to be a serious public health issue in developing countries. we analyzed the epidemiological data of cholera from 1976 to 2013 in shandong province, an eastern coastal area of china. a total of 250 vibrio cholerae isolates were selected for pcr analysis of virulence genes and pulsed-field gel electrophoresis (pfge). the analysis of the virulence genes showed that the positive rates for tcpa and tcpi were the highest among strains from the southwest region, which had the highest ...201727780663
achievements and challenges for the use of killed oral cholera vaccines in the global stockpile era.cholera remains an important but neglected public health threat, affecting the health of the poorest populations and imposing substantial costs on public health systems. cholera can be eliminated where access to clean water, sanitation, and satisfactory hygiene practices are sustained, but major improvements in infrastructure continue to be a distant goal. new developments and trends of cholera disease burden, the creation of affordable oral cholera vaccines (ocvs) for use in developing countrie ...201727813703
non-cholera vibrios: the microbial barometer of climate change.there is a growing interest in the role of climate change in driving the spread of waterborne infectious diseases, such as those caused by bacterial pathogens. one particular group of pathogenic bacteria - vibrios - are a globally important cause of diseases in humans and aquatic animals. these gram-negative bacteria, including the species vibrio vulnificus, vibrio parahaemolyticus and vibrio cholerae, grow in warm, low-salinity waters, and their abundance in the natural environment mirrors ambi ...201727843109
vibrio cholerae non-o1, non-o139 bacteraemia associated with pneumonia, italy 2016.this paper describes an elderly male patient, living in the veneto region, italy, who developed vibrio cholerae bacteraemia and pneumonia. some days previously, while on holiday in the lagoon of venice, he had been collecting clams in seawater, during which he suffered small abrasions of the skin. on admission to hospital, he was confused, had fever and a cough, but neither diarrhoea nor signs of gastroenteritis were found. both blood and stool cultures grew v. cholerae of non-o1 non-o-139 type, ...201727837335
calcium enhances bile salt-dependent virulence activation in vibrio cholerae.vibrio cholerae is the causative bacteria of the diarrheal disease cholera, but it also persists in aquatic environments, where it displays an expression profile that is distinct from that during infection. upon entry into the host, a tightly regulated circuit coordinates the induction of two major virulence factors: cholera toxin and a toxin-coregulated pilus (tcp). it has been shown that a set of bile salts, including taurocholate, serve as host signals to activate v. cholerae virulence throug ...201727849180
the live attenuated cholera vaccine cvd 103-hgr primes responses to the toxin-coregulated pilus antigen tcpa in subjects challenged with wild-type vibrio cholerae.one potential advantage of live attenuated bacterial vaccines is the ability to stimulate responses to antigens which are only expressed during the course of infection. to determine whether the live attenuated cholera vaccine cvd 103-hgr (vaxchora) results in antibody responses to the in vivo-induced toxin-coregulated pilus antigen tcpa, we measured iga and igg responses to vibrio cholerae o1 el tor tcpa in a subset of participants in a recently reported experimental challenge study. participant ...201727847368
biogeochemical and hydrological drivers of the dynamics of vibrio species in two patagonian estuaries.the ecology of the most relevant vibrio species for human health and their relation to water quality and biogeochemistry were studied in two estuaries in argentinian patagonia. vibrio cholerae and vibrio parahaemolyticus were reported in >29% of cases at the río colorado and río negro estuaries. neither the pandemic serogroups of vibrio cholerae o1, vibrio cholerae o139 nor the cholera toxin gene were detected in this study. however, several strains of v. cholerae (not o1 or o139) are able to ca ...201727871750
high genetic diversity of vibrio cholerae in the european lake neusiedler see is associated with intensive recombination in the reed habitat and the long-distance transfer of strains.coastal marine vibrio cholerae populations usually exhibit high genetic diversity. to assess the genetic diversity of abundant v. cholerae non-o1/non-o139 populations in the central european lake neusiedler see, we performed a phylogenetic analysis based on reca, toxr, gyrb and pyrh loci sequenced for 472 strains. the strains were isolated from three ecologically different habitats in a lake that is a hot-spot of migrating birds and an important bathing water. we also analyzed 76 environmental a ...201727871138
whole-genome enrichment provides deep insights into vibrio cholerae metagenome from an african river.the detection and typing of vibrio cholerae in natural aquatic environments encounter major methodological challenges related to the fact that the bacterium is often present in environmental matrices at very low abundance in nonculturable state. this study applied, for the first time to our knowledge, a whole-genome enrichment (wge) and next-generation sequencing (ngs) approach for direct genotyping and metagenomic analysis of low abundant v. cholerae dna (<50 genome unit/l) from natural water c ...201727888291
rules of engagement: the type vi secretion system in vibrio cholerae.microbial species often exist in complex communities where they must avoid predation and compete for favorable niches. the type vi secretion system (t6ss) is a contact-dependent bacterial weapon that allows for direct killing of competitors through the translocation of proteinaceous toxins. vibrio cholerae is a gram-negative pathogen that can use its t6ss during antagonistic interactions with neighboring prokaryotic and eukaryotic competitors. the t6ss not only promotes v. cholerae's survival du ...201728027803
genetically encodable bacterial flavin transferase for fluorogenic protein modification in mammalian cells.a bacterial flavin transferase (apbe) was recently employed for flavin mononucleotide (fmn) modification on the na(+)-translocating nadh:quinone oxidoreductase c (nqrc) protein in the pathogenic gram-negative bacterium vibrio cholerae. we employed this unique post-translational modification in mammalian cells and found that the fmn transfer reaction robustly occurred when nqrc and apbe were genetically targeted in the cytosol of live mammalian cells. moreover, nqrc expression in the endoplasmic ...201728035820
elucidation of the tidal influence on bacterial populations in a monsoon influenced estuary through simultaneous observations.the influence of tides on bacterial populations in a monsoon influenced tropical estuary was assessed through fine resolution sampling (1 to 3 h) during spring and neap tides from mouth to the freshwater end at four stations during pre-monsoon, monsoon and post-monsoon seasons. higher abundance of total bacterial count (tbc) in surface water near the river mouth, compared to the upstream, during pre-monsoon was followed by an opposite scenario during the monsoon when seasonally compared, it was ...201728035613
efficient and flexible preparation of biosynthetic microperoxidases.heme peptides and their derivatives, also called microperoxidases (mps), are employed as heme protein active site models, catalysts, and charge-transfer chromophores. in this work, two approaches to the biosynthesis of novel mps are described. in one method, heme peptides are expressed as c-terminal tags to the protein azurin and the mp is liberated by proteolytic cleavage by an endopeptidase. in an alternative approach, heme peptides are expressed as n-terminal tags to the cysteine protease dom ...201727957837
genomic profile of antibiotic resistant, classical ctxb positive vibrio cholerae o1 biotype el tor isolated in 2003 and 2005 from puri, india: a retrospective study.to examine eight strains of vibrio cholerae o1 isolated in 2003 and 2005 from puri, india, for antibiotic susceptibility, presence of virulence and regulatory genes, cholera toxin (ct) production, ctx arrangement and genomic profiles.201727934824
kinetics of antibody-secreting cell and fecal iga responses after oral cholera vaccination in different age groups in a cholera endemic country.immune responses to oral enteric vaccines in children and infants may be influenced by factors such as age, previous priming with related microorganisms and breast feeding. in this study, we aimed to determine optimal time points to assess immune responses to oral enteric vaccines in different clinical specimens. this was done by investigating antibody secreting cell (asc) and fecal antibody responses on different days after vaccination using the licensed oral cholera vaccine dukoral, containing ...201727916412
resource abundance and the critical transition to cooperation.cooperation is abundant in nature, occurring at all levels of biological complexity. yet cooperation is continually threatened by subversion from noncooperating cheaters. previous studies have shown that cooperation can nevertheless be maintained when the benefits that cooperation provides to relatives outweigh the associated costs. these fitness costs and benefits are not fixed properties, but can be affected by the environment in which populations reside. here, we describe how one environmenta ...201728036143
physiology of the vc-nhap paralogous group of cation-proton antiporters in vibrio cholerae.the genome of vibrio cholerae encodes three cation-proton antiporters of nhap-type, vc-nhap1, 2, and 3. to examine physiological roles of vc-nhap antiporters, triple δnhap1δnhap2δnhap3 and single δnhap3 deletion mutants of v. cholerae were constructed and characterized. vc-nhap3 was, for the first time, cloned and biochemically characterized. activity measurements on the inside-out membrane vesicle experimental model defined vc-nhap3 as a potassium-specific cation-proton antiporter. while elimin ...201728083717
peldor spectroscopy reveals two defined states of a sialic acid trap transporter sbp in solution.the tripartite atp-independent periplasmic (trap) transporters are a widespread class of membrane transporters in bacteria and archaea. typical substrates for trap transporters are organic acids including the sialic acid n-acetylneuraminic acid. the substrate binding proteins (sbp) of trap transporters are the best studied component and are responsible for initial high-affinity substrate binding. to better understand the dynamics of the ligand binding process, pulsed electron-electron double res ...201728076802
distribution of resistance genetic determinants among vibrio cholerae isolates of 2012 and 2013 outbreaks in ir iran.the objective of this study was to characterize antimicrobial resistance determinants in relation to antimicrobial susceptibility and genotyping profile in 20 clinical isolates of vibrio cholerae. all of the isolates were resistant to streptomycin. the second most prevalent resistance was observed to trimethoprim (75%), co-trimoxazole (60%), tetracycline (50%), and minocycline (45%). about 50% of the isolates fulfilled the criteria of multi drug resistance (mdr) phenotype. none of the isolates c ...201728062293
glycosylation characterization of an influenza h5n7 hemagglutinin series with engineered glycosylation patterns: implications for structure-function relationships.the glycosylation patterns of four recombinant h5 hemagglutinins (has) derived from a/mallard/denmark/64650/03 (h5n7) have been characterized. the proteins were expressed in (i) hek293t cells to produce complex glycoforms, (ii) hek293t cells treated with vibrio cholera neuraminidase to provide asialo-complex glycoforms, (iii) hek293s gnti(-) cells with predominantly the canonical man5glcnac2 glycoform, and (iv) drosophila s2 insect cells producing primarily paucimannose glycoforms. previously, t ...201728060516
new ligation independent cloning vectors for expression of recombinant proteins with a self-cleaving cpd/6xhis-tag.recombinant protein purification is a crucial step for biochemistry and structural biology fields. rapid robust purification methods utilize various peptide or protein tags fused to the target protein for affinity purification using corresponding matrices and to enhance solubility. however, affinity/solubility-tags often need to be removed in order to conduct functional and structural studies, adding complexities to purification protocols.201728056928
application of a paper based device containing a new culture medium to detect vibrio cholerae in water samples collected in haiti.cholera is now considered to be endemic in haiti, often with increased incidence during rainy seasons. the challenge of cholera surveillance is exacerbated by the cost of sample collection and laboratory analysis. a diagnostic tool is needed that is low cost, easy-to-use, and able to detect and quantify vibrio cholerae accurately in water samples within 18-24h, and perform reliably in remote settings lacking laboratory infrastructure and skilled staff. the two main objectives of this study were ...201728007529
characterization and genetic variation of vibrio cholerae isolated from clinical and environmental sources in thailand.cholera is still an important public health problem in several countries, including thailand. in this study, a collection of clinical and environmental v. cholerae serogroup o1, o139, and non-o1/non-o139 strains originating from thailand (1983 to 2013) was characterized to determine phenotypic and genotypic traits and to investigate the genetic relatedness. using a combination of conventional methods and whole genome sequencing (wgs), 78 v. cholerae strains were identified. wgs was used to deter ...201728103259
merr and chrr mediate blue light induced photo-oxidative stress response at the transcriptional level in vibrio cholerae.blue light (bl) is a major environmental factor that affects the physiology, behavior, and infectivity of bacteria as it contributes to the generation of reactive oxygen species (ros) while increasing photo-oxidative stress in cells. however, precise photo-oxidative response mechanism in non-phototrophic bacteria is yet to be elucidated. in this study, we investigated the effect of bl in vibrio cholerae by using genetics and transcriptome profiling. genome-wide analysis revealed that transcripti ...201728098242
unraveling the stereochemical and dynamic aspects of the catalytic site of bacterial peptidyl-trna hydrolase.bacterial peptidyl-trna hydrolase (pth; ec 3.1.1.29) hydrolyzes the peptidyl-trnas accumulated in the cytoplasm and thereby prevents cell death by alleviating trna starvation. x-ray and nmr studies of vibrio cholerae pth (vcpth) and mutants of its key residues involved in catalysis show that the activity and selectivity of the protein depends on the stereochemistry and dynamics of residues h24, d97, n118, and n14. d97-h24 interaction is critical for activity because it increases the nucleophilic ...201728096445
vibrio cholerae cholix toxin-induced hepg2 cell death is enhanced by tumor necrosis factor-alpha through ros and intracellular signal-regulated kinases.cholix toxin (cholix) from vibrio cholerae is a potent virulence factor exhibiting adp-ribosyltransferase activity on eukaryotic elongation factor 2 (eef2) of host cells, resulting in inhibition of protein synthesis. administration of cholix or its homologue pseudomonas exotoxin a (pea) to mice causes lethal hepatocyte damage. in this study, we demonstrate cytotoxicity of cholix on immortalized human hepatocytes in the presence of tumor necrosis factor α (tnf-α), which has been reported to play ...201728087840
vibrio mimicus as the rare cause of acute diarrheal illness.vibrio mimicus, although named for having many of the same virulent factors as vibrio cholera, is a rare cause of significant gastrointestinal illness. like many of the vibrio species, the strongest risk factor for v. mimicus infection is seafood consumption. after consuming crabs, a 64-year-old male presented with a three day history of voluminous, non-bloody, water diarrhea. the severity of the diarrhea caused the patient to have orthostatic hypotension and acute kidney injury, which improved ...201728045686
replication of vibrio cholerae classical ctx phage.the toxigenic classical and el tor biotype vibrio cholerae serogroup o1 strains are generated by lysogenization of host-type-specific cholera toxin phages (ctx phages). experimental evidence of the replication and transmission of an el tor biotype-specific ctx phage, ctx-1, has explained the evolution of v. cholerae el tor biotype strains. the generation of classical biotype strains has not been demonstrated in the laboratory, and the classical biotype-specific ctx phage, ctx-cla, is considered ...201728196886
systematic genetic dissection of pts in vibrio cholerae uncovers a novel glucose transporter and a limited role for pts during infection of a mammalian host.a common mechanism for high affinity carbohydrate uptake in microbial species is the phosphoenolpyruvate-dependent phosphotransferase system (pts). this system consists of a shared component, ei, which is required for all pts transport, and numerous carbohydrate uptake transporters. in vibrio cholerae, there are 13 distinct pts transporters. due to genetic redundancy within this system, the carbohydrate specificity of each of these transporters is not currently defined. here, using multiplex gen ...201728196401
identification of the catalytic ubiquinone-binding site of vibrio cholerae sodium-dependent nadh dehydrogenase: a novel ubiquinone-binding motif.the sodium-dependent nadh dehydrogenase (na(+)-nqr) is a key component of the respiratory chain of diverse prokaryotic species, including pathogenic bacteria. na(+)-nqr uses the energy released by electron transfer between nadh and ubiquinone (uq) to pump sodium, producing a gradient that sustains many essential homeostatic processes as well as virulence factor secretion and the elimination of drugs. the location of the uq binding site has been controversial, with two main hypotheses that sugges ...201728053088
a periplasmic polymer curves vibrio cholerae and promotes pathogenesis.pathogenic vibrio cholerae remains a major human health concern. v. cholerae has a characteristic curved rod morphology, with a longer outer face and a shorter inner face. the mechanism and function of this curvature were previously unknown. here, we identify and characterize crva, the first curvature determinant in v. cholerae. crva self-assembles into filaments at the inner face of cell curvature. unlike traditional cytoskeletons, crva localizes to the periplasm and thus can be considered a pe ...201728086090
killing by type vi secretion drives genetic phase separation and correlates with increased cooperation.by nature of their small size, dense growth and frequent need for extracellular metabolism, microbes face persistent public goods dilemmas. genetic assortment is the only general solution stabilizing cooperation, but all known mechanisms structuring microbial populations depend on the availability of free space, an often unrealistic constraint. here we describe a class of self-organization that operates within densely packed bacterial populations. through mathematical modelling and experiments w ...201728165005
transcriptional and post-transcriptional regulation of pst2 operon expression in vibrio cholerae o1.one of the most abundant proteins in v. cholerae o1 cells grown under inorganic phosphate (pi) limitation is psts, the periplasmic pi-binding component of the high-affinity pi transport system pst2 (pstscab), encoded in pst2 operon (psts-pstc2-psta2-pstb2). besides its role in pi uptake, pst2 has been also associated with v. cholerae virulence. however, the mechanisms regulating pst2 expression and the non-stoichiometric production of the pst2 components under pi-limitation are unknown. a comput ...201728242357
differential regulation of riboflavin supply genes in vibrio cholerae.riboflavin is the precursor of important redox cofactors such as flavin mononucleotide (fmn) and flavin adenine dinucleotide, required for several biological processes. vibrio cholerae, a pathogenic bacterium responsible for the cholera disease, possesses the ability to biosynthesize de novo as well as to uptake riboflavin through the riboflavin biosynthetic pathway (rbp) and the ribn importer, respectively. the intra-organism relationship between riboflavin biosynthesis and uptake functions has ...201728239422
structural and biochemical studies on vibrio cholerae hsp31 reveals a novel dimeric form and glutathione-independent glyoxalase activity.vibrio cholerae experiences a highly hostile environment at human intestine which triggers the induction of various heat shock genes. the hcha gene product of v. cholerae o395, referred to a hypothetical intracellular protease/amidase vchsp31, is one such stress-inducible homodimeric protein. our current study demonstrates that vchsp31 is endowed with molecular chaperone, amidopeptidase and robust methylglyoxalase activities. through site directed mutagenesis coupled with biochemical assays on v ...201728235098
oxyr-activated expression of dps is important for vibrio cholerae oxidative stress resistance and pathogenesis.vibrio cholerae is the causative agent of cholera, a dehydrating diarrheal disease. this gram-negative pathogen is able to modulate its gene expression in order to combat stresses encountered in both aquatic and host environments, including stress posed by reactive oxygen species (ros). in order to further the understanding of v. cholerae's transcriptional response to ros, we performed an rna sequencing analysis to determine the transcriptional profile of v. cholerae when exposed to hydrogen hyd ...201728151956
a cocktail of three virulent bacteriophages prevents vibrio cholerae infection in animal models.effective prevention strategies will be essential in reducing disease burden due to bacterial infections. here we harness the specificity and rapid-acting properties of bacteriophages as a potential prophylaxis therapy for cholera, a severely dehydrating disease caused by vibrio cholerae. to this end, we test a cocktail of three virulent phages in two animal models of cholera pathogenesis (infant mouse and rabbit models). oral administration of the phages up to 24 h before v. cholerae challenge ...201728146150
whole-genome sequencing of vibrio cholerae o1 el tor strains isolated in ukraine (2011) and russia (2014).here, we present the draft whole-genome sequence of vibrio cholerae o1 el tor strains 76 and m3265/80, isolated in mariupol, ukraine, and moscow, russia. the presence of various mutations detected in virulence-associated mobile elements indicates high genetic similarity of the strains reported here with new highly virulent variants of the cholera agent v. cholerae.201728232438
genetic characterization of vibrio cholerae o1 isolates from outbreaks between 2011 and 2015 in tanzania.cholera outbreaks have occurred in tanzania since 1974. to date, the genetic epidemiology of these outbreaks has not been assessed.201728219321
structure and function of vibrio cholerae accessory cholera enterotoxin in presence of gold nanoparticles: dependence on morphology.accessory cholera enterotoxin (ace) is a classical enterotoxin produced by vibrio cholerae, the causative agent for cholera. considering the crucial role of ace in pathogenesis of cholera, we explored the modulation of structure/function of ace using gold nanoparticles (aunps) of different size and shape - spherical (auns10 and auns100, the number indicating the diameter in nm) and rod (aunr10).201728215703
flufenamic acid protects against intestinal fluid secretion and barrier leakage in a mouse model of vibrio cholerae infection through nf-κb inhibition and ampk activation.nuclear factor kappa b (nf-κb)-mediated inflammatory responses play crucial roles in the pathogenesis of diarrhea caused by the vibrio cholerae el tor variant (el), which is a major bacterial strain causing recent cholera outbreaks. flufenamic acid (ffa) has previously been demonstrated to be a potent activator of amp-activated protein kinase (ampk), which is a negative regulator of nf-κb signaling. this study aimed to investigate the anti-diarrheal efficacy of ffa in a mouse model of el infecti ...201728119077
the fatty acid regulator fadr influences the expression of the virulence cascade in the el tor biotype of vibrio cholerae by modulating the levels of toxt via two different mechanisms.fadr is a master regulator of fatty acid (fa) metabolism that coordinates the pathways of fa degradation and biosynthesis in enteric bacteria. we show here that a δfadr mutation in the el tor biotype of vibrio cholerae prevents the expression of the virulence cascade by influencing both the transcription and the posttranslational regulation of the master virulence regulator toxt. fadr is a transcriptional regulator that represses the expression of genes involved in fa degradation, activates the ...201728115548
3-amino 1,8-naphthalimide, a structural analog of the anti-cholera drug virstatin inhibits chemically-biased swimming and swarming motility in vibrios.a screen for inhibitors of vibrio cholerae motility identified the compound 3-amino 1,8-naphthalimide (3-a18ni), a structural analog of the cholera drug virstatin. similar to virstatin, 3-a18ni diminished cholera toxin production. in contrast, 3-a18ni impeded swimming and/or swarming motility of v. cholerae and v. parahemolyticus suggesting that it could target the chemotaxis pathway shared by the polar and lateral flagellar system of vibrios. 3-a18ni did not inhibit the expression of v. cholera ...201728392408
fish as hosts of vibrio cholerae.vibrio cholerae, the causative agent of pandemic cholera, is abundant in marine and freshwater environments. copepods and chironomids are natural reservoirs of this species. however, the ways v. cholerae is globally disseminated are as yet unknown. here we review the scientific literature that provides evidence for the possibility that some fish species may be reservoirs and vectors of v. cholerae. so far, v. cholerae has been isolated from 30 fish species (22 freshwater; 9 marine). v. cholerae ...201728293221
an amoebal grazer of cyanobacteria requires cobalamin produced by heterotrophic bacteria.amoebae are unicellular eukaryotes that consume microbial prey through phagocytosis, playing a role in shaping microbial foodwebs. many amoebal species can be cultivated axenically in rich media or monoxenically with single bacterial prey species. here we characterize heterolobosean amoeba lpg3, a recent natural isolate, which is unable to grow on unicellular cyanobacteria, its primary food source, in the absence of a heterotrophic bacterium, a pseudomonas species coisolate. to investigate the m ...201728283521
mechanisms for pseudoalteromonas piscicida-induced killing of vibrios and other bacterial pathogens.pseudoalteromonas piscicida are gram-negative gammaproteobacteria found in the marine environment. three strains of pigmented p. piscicida were isolated from seawater and partially characterized by inhibition studies, electron microscopy, and proteolytic enzyme production. growth inhibition and death occurred around colonies of p. piscicida on lawns of the naturally-occurring marine pathogens vibrio vulnificus, v. parahaemolyticus, v. cholerae, photobacterium damselae and shewanella algae inhibi ...201728363962
networking in microbes: conjugative elements and plasmids in the genus alteromonas.to develop evolutionary models for the free living bacterium alteromonas the genome sequences of isolates of the genus have been extensively analyzed. however, the main genetic exchange drivers in these microbes, conjugative elements (ces), have not been considered in detail thus far. in this work, ces have been searched in several complete alteromonas genomes and their sequence studied to understand their role in the evolution of this genus. six genomes are reported here for the first time.201728056800
targeting and alteration of tight junctions by bacteria and their virulence factors such as clostridium perfringens enterotoxin.the integrity of tight junctions, which regulate paracellular permeability, is challenged by many bacterial pathogens. this is caused by inflammatory responses triggered by pathogens and direct interaction of bacteria or their toxins with host epithelial cells. in some cases, tight junction proteins represent receptors for cell surface proteins or toxins of the pathogen, such as clostridium perfringens enterotoxin (cpe). cpe causes diarrhea and cramps-the symptoms of a common foodborne illness, ...201727864644
fast growth conditions uncouple the final stages of chromosome segregation and cell division in escherichia coli.homologous recombination between the circular chromosomes of bacteria can generate chromosome dimers. they are resolved by a recombination event at a specific site in the replication terminus of chromosomes, dif, by dedicated tyrosine recombinases. the reaction is under the control of a cell division protein, ftsk, which assembles into active dna pumps at mid-cell during septum formation. previous studies suggested that activation of xer recombination at dif was restricted to chromosome dimers i ...201728358835
ribosome-dependent vibrio cholerae mrnase higb2 is regulated by a β-strand sliding mechanism.toxin-antitoxin (ta) modules are small operons involved in bacterial stress response and persistence. higba operons form a family of ta modules with an inverted gene organization and a toxin belonging to the rele/pare superfamily. here, we present the crystal structures of chromosomally encoded vibrio cholerae antitoxin (vchiga2), toxin (vchigb2) and their complex, which show significant differences in structure and mechanisms of function compared to the higba module from plasmid rts1, the defin ...201728334932
cross feeding of glucose metabolism byproducts of escherichia coli human gut isolates and probiotic strains affect survival of vibrio cholerae.vibrio cholerae converts glucose into either acid or the neutral end product acetoin and its survival in carbohydrate enriched media is linked to the nature of the byproducts produced. it has been demonstrated in this study that escherichia coli strain isolated from the gut of healthy human volunteers and the commonly used probiotic e. coli nissle strain that metabolize glucose to acidic byproducts drastically reduce the survival of v. cholerae strains irrespective of their glucose sensitivity a ...201728105081
interferon-inducible guanylate-binding proteins at the interface of cell-autonomous immunity and inflammasome activation.guanylate-binding proteins (gbps) are essential components of cell-autonomous immunity. in response to ifn signaling, gbps are expressed in the cytoplasm of immune and nonimmune cells, where they unleash their antimicrobial activity toward intracellular bacteria, viruses, and parasites. recent studies have revealed that gbps are essential for mediating activation of the caspase-1 inflammasome in response to the gram-negative bacteria salmonella enterica serovar typhimurium, francisella novicida, ...201727418355
ctxϕ: exploring new alternatives in host factor-mediated filamentous phage replications.for a long time ff phages from escherichia coli provided the majority of the knowledge about the rolling circle replication mechanism of filamentous phages. host factors involved in coliphages replication have been fully identified. based on these studies, the function of rep protein as the accessory helicase directly implicated in filamentous phage replication was considered a paradigm. we recently reported that the replication of some filamentous phages from vibrio cholerae, including the chol ...201727607139
random versus cell cycle-regulated replication initiation in bacteria: insights from studying vibrio cholerae chromosome 2.bacterial chromosomes initiate replication at a fixed time in the cell cycle, whereas there is generally no particular time for plasmid replication initiation or chromosomal replication initiation from integrated plasmids. in bacteria with divided genomes, the replication system of one of the chromosomes typically resembles that of bacteria with undivided genomes, whereas the remaining chromosomes have plasmid-like replication systems. for example, in vibrio cholerae, a bacterium with two chromo ...201727903655
in vitro antibacterial activity of aqueous and ethanol extracts of aristolochia indica and toddalia asiatica against multidrug-resistant bacteria.bacteria have developed multidrug resistance against available antimicrobial agents. infectious diseases caused by these multidrug-resistant bacteria are major causes of morbidity and mortality in human beings. synthetic drugs are expensive and inadequate for the treatment of diseases, causing side effects and ineffective against multidrug-resistant bacteria. the medicinal plants are promising to have effective antimicrobial property due to presence of phytochemical compounds like alkaloids, fla ...201726997710
immunochromatographic detection of the heat-labile enterotoxin of enterotoxigenic escherichia coli with cross-detection of cholera toxin.here, we report the development of an immunochromatographic test strip that can detect heat-labile enterotoxin (lt) produced by enterotoxigenic escherichia coli. five types of monoclonal antibody (mab)-producing hybridomas were isolated: three mabs were a subunit specific and two were b subunit specific. four mabs also cross-reacted with both lt proteins derived from swine and human e. coli strains, but only one mab 57b9 additionally cross-reacted with cholera toxin. thus, mab 57b9 was used to f ...201727940044
attachment of 13 types of foodborne bacteria to jalapeño and serrano peppers and antibacterial effect of roselle calyx extracts, sodium hypochlorite, colloidal silver, and acetic acid against these foodborne bacteria on peppers.chili peppers are a very important crop in mexico. however, these peppers have been associated with salmonella infection outbreaks in the united states, and salmonella and diarrheagenic escherichia coli pathotypes have been isolated from jalapeño and serrano peppers in mexico. to decrease microbial contamination of fruits and vegetables, chemical agents are commonly used; however, chemical agents used to eliminate pathogenic bacteria on vegetables have a limited antimicrobial effect. roselle ( h ...201728199144
structure and dynamics of type iii periplasmic proteins vcfhud and vchutb reveal molecular basis of their distinctive ligand binding properties.molecular mechanisms of xenosiderophore and heme acquisitions using periplasmic binding protein (pbp) dependent atp-binding cassette transporters to scavenge the essential nutrient iron are elusive yet in vibrio cholerae. our current study delineates the structures, dynamics and ligand binding properties of two type iii pbps of v. cholerae, vcfhud and vchutb. through crystal structures and fluorescence quenching studies we demonstrate unique features of vcfhud to bind both hydroxamate and catech ...201728216648
identification and antimicrobial resistance patterns of bacterial enteropathogens from children aged 0-59 months at the university teaching hospital, lusaka, zambia: a prospective cross sectional study.bacterial diarrhoeal disease is among the most common causes of mortality and morbidity in children 0-59 months at the university teaching hospital in lusaka, zambia. however, most cases are treated empirically without the knowledge of aetiological agents or antimicrobial susceptibility patterns. the aim of this study was, therefore, to identify bacterial causes of diarrhoea and determine their antimicrobial susceptibility patterns in stool specimens obtained from the children at the hospital.201728152988
xer site specific recombination: double and single recombinase systems.the separation and segregation of newly replicated bacterial chromosomes can be constrained by the formation of circular chromosome dimers caused by crossing over during homologous recombination events. in escherichia coli and most bacteria, dimers are resolved to monomers by site-specific recombination, a process performed by two chromosomally encoded tyrosine recombinases (xerc and xerd). xercd recombinases act at a 28 bp recombination site dif, which is located at the replication terminus reg ...201728373867
structural insights into the secretin translocation channel in the type ii secretion system.the secretin gspd of the type ii secretion system (t2ss) forms a channel across the outer membrane in gram-negative bacteria to transport substrates from the periplasm to the extracellular milieu. the lack of an atomic-resolution structure of the gspd channel hinders the investigation of substrate translocation mechanism of t2ss. here we report cryo-em structures of two gspd channels (∼1 mda), from escherichia coli k12 and vibrio cholerae, at ∼3 å resolution. the structures reveal a pentadecamer ...201728067918
stringent factor and proteolysis control of sigma factor rpos expression in vibrio cholerae.vibrio cholerae can colonize the gastrointestinal track of humans and cause the disease cholera. during colonization, the alternative sigma factor, rpos, controls a process known as "mucosal escape response," defining a specific spatial and temporal response and effecting chemotaxis and motility. in this report, the expression and proteolytic control of rpos in v. cholerae was characterized. to date, aspects of proteolysis control, the involved components, and proteolysis regulation have not bee ...201728228329
surface expression of helicobacter pylori hpaa adhesion antigen on vibrio cholerae, enhanced by co-expressed enterotoxigenic escherichia coli fimbrial antigens.helicobacter pylori infection can cause peptic ulceration and is associated with gastric adenocarcinoma. this study aimed to construct and characterize a non-virulent vibrio cholerae o1 strain, which grows more rapidly than h. pylori, as vector for h. pylori antigens for possible use as a vaccine strain against h. pylori. this was done by recombinant expression of the h. pylori adhesion antigen hpaa alone or, as a proof of principle, together with different colonization factor (cf) antigens of e ...201728215587
induction of immunomodulatory mir-146a and mir-155 in small intestinal epithelium of vibrio cholerae infected patients at acute stage of cholera.the potential immunomodulatory role of micrornas in small intestine of patients with acute watery diarrhea caused by vibrio cholerae o1 or enterotoxigenic escherichia coli (etec) infection was investigated. duodenal biopsies were obtained from study-participants at the acute (day 2) and convalescent (day 21) stages of disease, and from healthy individuals. levels of mir-146a, mir-155 and mir-375 and target gene (irak1, traf6, card10) and 11 cytokine mrnas were determined by qrt-pcr. the cellular ...201728319200
antibacterial and antispasmodic activities of a dichloromethane fraction of an ethanol extract of stem bark of piliostigma reticulatum.this study presents the antispasmodic and antibacterial properties of an ethanol extract and fractions the of stem bark of piliostigma reticulatum.201725883517
pathogenic mechanisms of actin cross-linking toxins: peeling away the layers.actin cross-linking toxins are produced by gram-negative bacteria from vibrio and aeromonas genera. the toxins were named actin cross-linking domains (acd), since the first and most of the subsequently discovered acds were found as effector domains in larger martx and vgrg toxins. among recognized human pathogens, acd is produced by vibrio cholerae, vibrio vulnificus, and aeromonas hydrophila. upon delivery to the cytoplasm of a host cell, acd covalently cross-links actin monomers into non-polym ...201727858184
the expanding role of type ii secretion in bacterial pathogenesis and beyond.type ii secretion (t2s) is one means by which gram-negative pathogens secrete proteins into the extracellular milieu and/or host organisms. based upon recent genome sequencing, it is clear that t2s is largely restricted to the proteobacteria, occurring in many, but not all genera in the α-, β-, γ-, and δ- classes. prominent human and/or animal pathogens that express a t2s system(s) include acinetobacter baumannii, burkholderia pseudomallei, chlamydia trachomatis, escherichia coli, klebsiella pne ...201728264910
a comparative study of cold- and warm-adapted endonucleases a using sequence analyses and molecular dynamics simulations.the psychrophilic and mesophilic endonucleases a (enda) from aliivibrio salmonicida (vsenda) and vibrio cholera (vcenda) have been studied experimentally in terms of the biophysical properties related to thermal adaptation. the analyses of their static x-ray structures was no sufficient to rationalize the determinants of their adaptive traits at the molecular level. thus, we used molecular dynamics (md) simulations to compare the two proteins and unveil their structural and dynamical differences ...201728192428
raw ready-to-eat seafood safety: microbiological quality of the various seafood species available in fishery, hyper and online markets.microbiological quality of 206 raw ready-to-eat seafood samples was investigated according to species (gizzard shad, halibut, rockfish, tuna, oyster and squid) and distribution channels (fishery, hyper and online market). enumeration of aerobic plate count and total coliforms (tc) and pathogenic bacteria (bacillus cereus, staphylococcus aureus and vibrio parahaemolyticus) was performed, and level of microbiological quality was classified into four groups: satisfactory, acceptable, unsatisfactory ...201727747902
antimicrobial effects of novel peptides cot2 and sot2 derived from crocodylus siamensis and pelodiscus sinensis ovotransferrins.in light of the increasing threat of bacterial drug resistance to human health on a global scale, research and development of antimicrobial peptides as a novel class of potent antibiotics has gained considerable attention. the present study focuses on the structural evaluation and membrane interaction of two new cationic antimicrobial peptides, cot2 and sot2, derived from siamese crocodile (crocodylus siamensis) and chinese softshell turtle (pelodiscus sinensis) ovotransferrins. here, cot1 (+3) ...201728159460
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