Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| pharmacological inhibition of quorum sensing for the treatment of chronic bacterial infections. | traditional treatment of infectious diseases is based on compounds that aim to kill or inhibit bacterial growth. a major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. the discovery of bacterial-communication systems (quorum-sensing systems), which orchestrate important temporal events during the infection process, has afforded a novel opportunity to ameliorate bacterial infection by means other than growth inhibition. compounds able t ... | 2003 | 14597754 |
| a new evaluation of our life-support system. | 2003 | 12949578 | |
| soft rot erwiniae: from genes to genomes. | summary the soft rot erwiniae, erwinia carotovora ssp. atroseptica (eca), e. carotovora ssp. carotovora (ecc) and e. chrysanthemi (ech) are major bacterial pathogens of potato and other crops world-wide. we currently understand much about how these bacteria attack plants and protect themselves against plant defences. however, the processes underlying the establishment of infection, differences in host range and their ability to survive when not causing disease, largely remain a mystery. this rev ... | 2003 | 20569359 |
| salt stress activation of wound-related genes in tomato plants. | plants respond to various stresses by expressing distinct sets of genes. the effects of multiple stresses on plants and their interactions are not well understood. we have discovered that salt stress causes the accumulation of proteinase inhibitors and the activation of other wound-related genes in tomato (lycopersicon esculentum) plants. salt stress was also found to enhance the plant's response to wounding locally and systemically. the tomato mutant (def-1), which has an impairment in the octa ... | 2003 | 12913164 |
| modulation of cyp79 genes and glucosinolate profiles in arabidopsis by defense signaling pathways. | glucosinolates are natural plant products that function in the defense toward herbivores and pathogens. plant defense is regulated by multiple signal transduction pathways in which salicylic acid (sa), jasmonic acid, and ethylene function as signaling molecules. glucosinolate content was analyzed in arabidopsis wild-type plants in response to single or combinatorial treatments with methyljasmonate (meja), 2,6-dichloro-isonicotinic acid, ethylene, and 2,4-dichloro-phenoxyacetic acid, or by woundi ... | 2003 | 12529537 |
| enhancement of population size of a biological control agent and efficacy in control of bacterial speck of tomato through salicylate and ammonium sulfate amendments. | sodium salicylate and ammonium sulfate were applied to leaf surfaces along with suspensions of the biological control agents pseudomonas syringae cit7(pnah7), which catabolizes salicylate, and cit7, which does not catabolize salicylate, to determine whether enhanced biological control of bacterial speck of tomato could be achieved. foliar amendment with salicylate alone significantly enhanced the population size and the efficacy of cit7(pnah7), but not of cit7, on tomato leaves. application of a ... | 2003 | 12571060 |
| vibrio harveyi quorum sensing: a coincidence detector for two autoinducers controls gene expression. | in a process called quorum sensing, bacteria communicate with one another by exchanging chemical signals called autoinducers. in the bioluminescent marine bacterium vibrio harveyi, two different auto inducers (ai-1 and ai-2) regulate light emission. detection of and response to the v.harveyi autoinducers are accomplished through two two-component sensory relay systems: ai-1 is detected by the sensor luxn and ai-2 by luxpq. here we further define the v.harveyi quorum-sensing regulon by identifyin ... | 2003 | 12574123 |
| rhamnogalacturonate lyase rhie is secreted by the out system in erwinia chrysanthemi. | supernatants of rhamnose-induced erwinia chrysanthemi strain 3937 cultures contain a principal secreted protein named rhie. a rhie mutant has been found among a set of rhamnose-induced mudi1681 lacz fusions. rhie is a 62-kda protein that has rhamnogalacturonate lyase activity on rhamnogalacturonan i (rg-i). it does not require a divalent cation for its activity and has an optimal ph of 6.0. rhie expression is strongly induced in the presence of rhamnose but is also regulated by pect and crp, two ... | 2003 | 12591882 |
| a single gene that promotes interaction of a phytopathogenic bacterium with its insect vector, drosophila melanogaster. | insects are major vectors of plant and animal disease, and bacterial phytopathogens are often disseminated by flies. we have previously reported that some isolates of the phytopathogenic bacterial species erwinia carotovora infect drosophila and activate an immune response. using a genetic screen, we have now identified two genes that are required by e. carotovora to infect drosophila. one of these genes has a regulatory role whereas the other, evf, confers an infectious phenotype: its transfer ... | 2003 | 12612613 |
| mutational analysis of the residue at position 48 in the salmonella enterica serovar typhimurium phoq sensor kinase. | the phop/phoq two-component regulatory system of salmonella enterica serovar typhimurium plays an essential role in controlling virulence by mediating the adaptation to mg(2+) depletion. the pho-24 allele of phoq harbors a single amino acid substitution (t48i) in the periplasmic domain of the phoq histidine kinase sensor. this mutation has been shown to increase net phosphorylation of the phop response regulator. we analyzed the effect on signaling by phop/phoq of various amino acid substitution ... | 2003 | 12618457 |
| quorum-sensing system and stationary-phase sigma factor (rpos) of the onion pathogen burkholderia cepacia genomovar i type strain, atcc 25416. | bacterial strains belonging to burkholderia cepacia can be human opportunistic pathogens, plant pathogens, and plant growth promoting and have remarkable catabolic activity. b. cepacia consists of several genomovars comprising what is now known as the b. cepacia complex. here we report the quorum-sensing system of a genomovar i onion rot type strain atcc 25416. quorum sensing is a cell-density-dependent regulatory response which involves the production of n-acyl homoserine lactone (hsl) signal m ... | 2003 | 12620866 |
| two families of mechanosensitive channel proteins. | mechanosensitive (ms) channels that provide protection against hypoosmotic shock are found in the membranes of organisms from the three domains of life: bacteria, archaea, and eucarya. two families of ubiquitous ms channels are recognized, and these have been designated the mscl and mscs families. a high-resolution x-ray crystallographic structure is available for a member of the mscl family, and extensive molecular genetic, biophysical, and biochemical studies conducted in many laboratories hav ... | 2003 | 12626684 |
| crystal structure of enterococcus faecalis slya-like transcriptional factor. | the crystal structure of a slya transcriptional regulator at 1.6 a resolution is presented, and structural relationships between members of the marr/slya family are discussed. the slya family, which includes slya, rap, hor, and rova proteins, is widely distributed in bacterial and archaeal genomes. current evidence suggests that slya-like factors act as repressors, activators, and modulators of gene transcription. these proteins have been shown to up-regulate the expression of molecular chaperon ... | 2003 | 12649270 |
| erwinia carotovora subsp. carotovora and erwinia-derived elicitors hrpn and peha trigger distinct but interacting defense responses and cell death in arabidopsis. | we have used an hrp-positive strain of the soft rot pathogen erwinia carotovora subsp. carotovora to elucidate plant responses to this bacterial necrotroph. purified virulence determinants, harpin (hrpn) and polygalacturonase (peha), were used as tools to facilitate this analysis. we show that hrpn elicits lesion formation in arabidopsis and tobacco and triggers systemic resistance in arabidopsis. establishment of resistance is accompanied by the expression of salicylic acid (sa)-dependent, but ... | 2003 | 12650449 |
| comparative study of regulatory mechanisms for pectinase production by erwinia carotovora subsp. carotovora and erwinia chrysanthemi. | the production of pectinase, the major virulence determinant of soft-rot erwinia species, is controlled by many regulatory factors. we focused on the major regulatory proteins, kdgr, crp, pir, and pecs, characterized mainly in e. chrysanthemi, and tested for their presence and function in the control of pectate lyase (pel) and polygalacturonase (peh) production in e. carotovora subsp. carotovora. homologues of kdgr and crp but not of pir and pecs were detected by southern blot analyses in e. car ... | 2003 | 12650454 |
| novel virulence-associated type ii secretion system unique to high-pathogenicity yersinia enterocolitica. | yersinia enterocolitica strains comprise an important group of bacterial enteropathogens that cause a broad range of gastrointestinal syndromes. three groups are distinguishable within this bacterial species, namely, the nonpathogenic group (biotype 1a strains), the low-pathogenicity, non-mouse-lethal group (biotypes 2 to 5), and the high-pathogenicity, mouse-lethal group (biotype 1b). to date, the presence of the high-pathogenicity island (hpi), a chromosomal locus that encodes the yersiniabact ... | 2003 | 12654803 |
| isolation and antifungal and antioomycete activities of aerugine produced by pseudomonas fluorescens strain mm-b16. | the bacterial strain mm-b16, which showed strong antifungal and antioomycete activity against some plant pathogens, was isolated from a mountain forest soil in korea. based on the physiological and biochemical characteristics and 16s ribosomal dna sequence analysis, the bacterial strain mm-b16 was identical to pseudomonas fluorescens. an antibiotic active against colletotrichum orbiculare and phytophthora capsici in vitro and in vivo was isolated from the culture filtrates of p. fluorescens stra ... | 2003 | 12676678 |
| elevation of three subspecies of pectobacterium carotovorum to species level: pectobacterium atrosepticum sp. nov., pectobacterium betavasculorum sp. nov. and pectobacterium wasabiae sp. nov. | a collection of 42 strains belonging to the five subspecies of pectobacterium carotovorum (subspecies atrosepticum, betavasculorum, carotovorum, odoriferum and wasabiae) and 11 reference and type strains of biovars of pectobacterium chrysanthemi, pectobacterium cacticidum and brenneria paradisiaca were studied by dna-dna hybridization, numerical taxonomy of 120 phenotypic characteristics, serology and new phylogenetic analysis of previously reported sequences from a database of aligned 16s rdna ... | 2003 | 12710602 |
| sweet pepper ferredoxin-like protein ( pflp) gene as a novel selection marker for orchid transformation. | a novel method for selection of transgenic plants utilizing the sweet pepper ( capsicum annuum l.) ferredoxin-like protein ( pflp) gene as selection marker and erwinia carotovora as the selection agent has been developed. an expression vector containing a pflp cdna driven by a cauliflower mosaic virus 35s promoter was successfully transformed into protocorm-like bodies of oncidium orchid by agrobacterium tumefaciens and particle bombardment, respectively. erwinia carotovora was used as a selecti ... | 2003 | 12721849 |
| enhanced resistance to phytophthora infestans and alternaria solani in leaves and tubers, respectively, of potato plants with decreased activity of the plastidic atp/adp transporter. | recently, it has been reported that tubers of transgenic potato ( solanum tuberosum l.) plants with decreased activity of the plastidic atp/adp transporter (aatp1) contain less starch, despite having an increased glucose level [p. geigenberger et al. (2001) plant physiol 125:1667-1678]. the metabolic alterations correlated with enhanced resistance to the bacterium erwinia carotovora. here it is shown that transgenic potato tubers, possessing less starch yet increased glucose levels due to the ex ... | 2003 | 12721851 |
| paex, a second pectin acetylesterase of erwinia chrysanthemi 3937. | erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. pectin is a complex polysaccharide. the main chain is constituted of galacturonate residues, and some of them are modified by methyl and/or acetyl esterification. esterases are necessary to remove these modifications and, thus, to facilitate the further degradation of the polysaccharidic chain. in addition to paey, the first pectin acetylesterase identified in the e. chrysa ... | 2003 | 12730169 |
| characterization of the xanthomonas axonopodis pv. glycines hrp pathogenicity island. | we sequenced an approximately 29-kb region from xanthomonas axonopodis pv. glycines that contained the hrp type iii secretion system, and we characterized the genes in this region by tn3-gus mutagenesis and gene expression analyses. from the region, hrp (hypersensitive response and pathogenicity) and hrc (hrp and conserved) genes, which encode type iii secretion systems, and hpa (hrp-associated) genes were identified. the characteristics of the region, such as the presence of many virulence gene ... | 2003 | 12730176 |
| quorum sensing in plant-pathogenic bacteria. | quorum sensing (qs) allows bacteria to assess their local population density and/or physical confinement via the secretion and detection of small, diffusible signal molecules. this review describes how phytopathogenic bacteria have incorporated qs mechanisms into complex regulatory cascades that control genes for pathogenicity and colonization of host surfaces. traits regulated by qs include the production of extracellular polysaccharides, degradative enzymes, antibiotics, siderophores, and pigm ... | 2003 | 12730390 |
| peh production, flagellum synthesis, and virulence reduced in erwinia carotovora subsp. carotovora by mutation in a homologue of cytr. | erwinia carotovora subsp. carotovora is a causal agent of soft-rot diseases in a wide variety of plants. here, we have isolated a new regulatory factor involved in the virulence of e. carotovora subsp. carotovora by in vivo insertional mutagenesis using a transposon tn5. the gene was homologous to cytr encoding a transcriptional repressor of nucleoside uptake and catabolism genes in escherichia coli, salmonella typhimurium, and vibrio cholerae. phenotypic characterization of a nonpolar deletion ... | 2003 | 12744509 |
| [the study of erwinia carotovora bacteriocins in the nalidixic acid resistant erwinia carotovora]. | a novel approach is proposed for the study of the macromolecular bacteriocins of erwinia carotovora (mctvs). the approach lies in that the bacteriocinogeny of pectolytic erwinia is studied using a lawn of a bacterial mutant resistant to nalidixic acid, an inducer of mctvs. the high efficiency of this approach was demonstrated by studying carotovoricins in 104 different e. carotovora strains, 88% of which bear mctvs, distinguished by the morphology of zones of induced lysis on a lawn of susceptib ... | 2003 | 12751244 |
| mutation of luxs of streptococcus pneumoniae affects virulence in a mouse model. | the luxs protein is required for the biosynthesis of the type 2 autoinducer (ai-2), which is involved in quorum sensing in a wide range of bacterial species. we have determined the effects of a defined luxs mutation on the virulence of streptococcus pneumoniae. although the luxs mutant displayed reduced virulence relative to its wild-type parent, the type 2 strain d39, it was by no means avirulent in a mouse model. after intranasal administration, the luxs mutant was able to colonize the nasopha ... | 2003 | 12761100 |
| ahld, an n-acylhomoserine lactonase in arthrobacter sp., and predicted homologues in other bacteria. | quorum sensing is a signalling mechanism that controls diverse biological functions, including virulence, via n-acylhomoserine lactone (ahl) signal molecules in gram-negative bacteria. with the aim of isolating strains or enzymes capable of blocking quorum sensing by inactivating ahl, bacteria were screened for ahl degradation by their ability to utilize n-3-oxohexanoyl-l-homoserine lactone (ohhl) as the sole carbon source. among four isolates, strain ibn110, identified as arthrobacter sp., was ... | 2003 | 12777494 |
| the sweet pepper ferredoxin-like protein (pflp) conferred resistance against soft rot disease in oncidium orchid. | genetic engineering to date has not been used to introduce disease resistance genes into the orchid gene pool. the ferredoxin-like protein gene originally isolated from sweet pepper is thought to function as a natural defense against infection due to its antimicrobial properties. hence it was reasoned that introduction of this gene might produce oncidium plants resistant to erwinia carotovora, the causal agent for the soft rot disease. an expression vector containing sweet pepper ferredoxin-like ... | 2003 | 12779121 |
| inhibition and alternate substrate studies on the mechanism of carbapenam synthetase from erwinia carotovora. | the erwinia carotorova cara, carb, and carc gene products are essential for the biosynthesis of (5r)-carbapen-2-em-3-carboxylic acid, the simplest carbapenem beta-lactam antibiotic. cara (hereafter named carbapenam synthetase) has been proposed to catalyze formation of (3s,5s)-carbapenam-3-carboxylic acid from (2s,5s)-5-carboxymethyl proline based on characterization of the products of fermentation experiments in escherichia coli cells transformed with pet24a/carb and pet24a/carab, and on sequen ... | 2003 | 12820893 |
| a novel potato defence-related alcohol:nadp+ oxidoreductase induced in response to erwinia carotovora. | identification of solanum tuberosum genes responsive to culture filtrates (cf) from erwinia carotovora subsp. carotovora led to the isolation of a full-length cdna with high sequence similarity to several alcohol dehydrogenases. accumulation of transcripts corresponding to this defence-related alcohol dehydrogenase (drd-1) was rapidly induced in cf-treated and wounded plants. the gene was also responsive to molecules involved in defence signalling such as salicylic acid, methyl jasmonate and eth ... | 2003 | 12825698 |
| the erwinia chrysanthemi phop-phoq operon plays an important role in growth at low ph, virulence and bacterial survival in plant tissue. | we have studied the role of acidic ph as a barrier for the colonization of the plant apoplast by erwinia chrysanthemi. a minitransposon containing a promoterless reporter gene, gus, was used for random mutagenesis of the bacterial genome. an acid-sensitive mutant, named bt119, was isolated and had the following differential features with respect to the wild-type strain: (i) inability to grow at ph </= 5.5; (ii) decreased survival at acid ph and in plant tissues; (iii) increased susceptibility to ... | 2003 | 12828634 |
| identification of a new ribosomal protection type of tetracycline resistance gene, tet(36), from swine manure pits. | previously, only one ribosome protection type of a tetracycline resistance gene, tetq, had been identified in bacteroides spp. during an investigation of anaerobic bacteria present in swine feces and manure storage pits, a tetracycline-resistant bacteroides strain was isolated. subsequent analysis showed that this new bacteroides strain, bacteroides sp. strain 139, did not contain tetq but contained a previously unidentified tetracycline resistance gene. sequence analysis showed that the tetracy ... | 2003 | 12839793 |
| detection and diversity assessment of xylella fastidiosa in field-collected plant and insect samples by using 16s rrna and gyrb sequences. | the causal agent of diseases in many economically important plants is attributed to the xylem-limited bacterium xylella fastidiosa. the detection of this plant pathogen has been hampered due to its difficult isolation and slow growth on plates. nearly complete nucleotide sequences of the 16s rrna gene and partial sequences of the gyrb gene were determined for 18 strains of x. fastidiosa isolated from different plant hosts. a phylogenetic analysis, based on gyrb, grouped strains in three clusters ... | 2003 | 12839807 |
| sequence of the escherichia coli o121 o-antigen gene cluster and detection of enterohemorrhagic e. coli o121 by pcr amplification of the wzx and wzy genes. | the dna sequence of the 15,155-bp o-antigen gene cluster of escherichia coli o121 was determined, and 14 open reading frames were identified (all had the same transcriptional direction). analyses of results indicated that the wzx (o-antigen flippase) and wzy (o-antigen polymerase) genes were e. coli o121 specific, so regions in these two genes were chosen for development of pcr assays. the pcr assays using dna from 99 e. coli o121 strains, strains representative of non-o121 e. coli serogroups, a ... | 2003 | 12843098 |
| sm-like proteins in eubacteria: the crystal structure of the hfq protein from escherichia coli. | the hfq protein was discovered in escherichia coli in the early seventies as a host factor for the qbeta phage rna replication. during the last decade, it was shown to be involved in many rna processing events and remote sequence homology indicated a link to spliceosomal sm proteins. we report the crystal structure of the e.coli hfq protein showing that its monomer displays a characteristic sm-fold and forms a homo-hexamer, in agreement with former biochemical data. overall, the structure of the ... | 2003 | 12853626 |
| [the bactericidal activity of lectins from nitrogen-fixing bacilli]. | lectins i and ii isolated from the nitrogen-fixing soil bacterium paenibacillus polymyxa 1460 were found to be able to suppress the growth of rhizobium leguminosarum 252 and bacillus subtilis 36 at nearly all the concentrations tested (from 1 to 10 micrograms/ml). lectin i was also inhibitory to azospirillum brasilense 245 and erwinia carotovora subsp. citrulis 603, while lectin ii exerted bactericidal activity against xanthomonas campestris b-610 and b-611 and a. brasilense 245. the bacillar le ... | 2003 | 12901008 |
| the ti plasmid of agrobacterium tumefaciens harbors an attm-paralogous gene, aiib, also encoding n-acyl homoserine lactonase activity. | the agrobacterium tumefaciens c58 genome contains three putative n-acyl homoserine lactone (acyl-hsl) hydrolases, which are closely related to the lactonase aiia of bacillus. when expressed in escherichia coli, two of the putative acyl-hsl hydrolases, attm and aiib, conferred the ability to degrade acyl-hsls on the host. in erwinia strain 6276, the lactonases reduced the endogenous acyl-hsl level and the bacterial virulence in planta. | 2003 | 12902298 |
| novel bacteria degrading n-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria. | bacteria degrading the quorum-sensing (qs) signal molecule n-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic rep-pcr and rrs pcr-rflp profiles. representative strains from each group were identified as members of the genera pseudomonas, comamonas, variovorax and rhodococcus: all these isolates degraded n-acylhomoserine lactones other than the hexanoic acid derivative, albei ... | 2003 | 12904538 |
| the drosophila forkhead transcription factor foxo mediates the reduction in cell number associated with reduced insulin signaling. | forkhead transcription factors belonging to the foxo subfamily are negatively regulated by protein kinase b (pkb) in response to signaling by insulin and insulin-like growth factor in caenorhabditis elegans and mammals. in drosophila, the insulin-signaling pathway regulates the size of cells, organs, and the entire body in response to nutrient availability, by controlling both cell size and cell number. in this study, we present a genetic characterization of dfoxo, the only drosophila foxo ortho ... | 2003 | 12908874 |
| proteomic analysis of wild-type sinorhizobium meliloti responses to n-acyl homoserine lactone quorum-sensing signals and the transition to stationary phase. | proteome analysis revealed that two long-chain n-acyl homoserine lactones (ahls) produced by sinorhizobium meliloti 1021 induced significant differences in the accumulation of more than 100 polypeptides in early-log-phase cultures of the wild type. fifty-six of the corresponding proteins have been identified by peptide mass fingerprinting. the proteins affected by addition of these two ahls had diverse functions in carbon and nitrogen metabolism, energy cycles, metabolite transport, dna synthesi ... | 2003 | 12923075 |
| regulation of the vitamin b12 metabolism and transport in bacteria by a conserved rna structural element. | cobalamin in the form of adenosylcobalamin (ado-cbl) is known to repress expression of genes for vitamin b(12) biosynthesis and be transported by a posttranscriptional regulatory mechanism, which involves direct binding of ado-cbl to 5'untranslated gene regions (5'utr). using comparative analysis of genes and regulatory regions, we identified a highly conserved rna structure, the b12-element, which is widely distributed in 5'utrs of vitamin b(12)-related genes in eubacteria. multiple alignment o ... | 2003 | 12923257 |
| insertion sequence isecp1b is involved in expression and mobilization of a bla(ctx-m) beta-lactamase gene. | the genetic structures (ca. 10-kb dna fragment) surrounding the plasmid-borne extended-spectrum beta-lactamase bla(ctx-m-19) gene in a klebsiella pneumoniae clinical isolate were determined. this beta-lactamase gene was part of a 4,797-bp transposon inserted inside orf1 of tn1721. inside this transposon, bla(ctx-m-19) was bracketed upstream and downstream by insertion sequences ise cp1b and is903d, respectively, and further downstream by a truncated gene encoding an outer membrane protein for ir ... | 2003 | 12936998 |
| directed expression of the hiv-1 accessory protein vpu in drosophila fat-body cells inhibits toll-dependent immune responses. | human immunodeficiency virus 1 (hiv-1) expresses several accessory proteins that manipulate various host-cell processes to achieve optimum replicative efficiency. one of them, viral protein u (vpu), has been shown to interfere with the cellular degradation machinery through interaction with scf(beta-trcp) complexes. to learn more about vpu function in vivo, we used the genetically tractable fruit fly, drosophila melanogaster. our results show that the directed expression of vpu, but not the non- ... | 2003 | 12973300 |
| role of rsma in the regulation of swarming motility and virulence factor expression in proteus mirabilis. | swarming by proteus mirabilis involves differentiation of typical short vegetative rods into filamentous hyper-flagellated swarm cells that undergo cycles of rapid and co-ordinated population migration across surfaces and exhibit high levels of virulence gene expression. rsma (repressor of secondary metabolites) and csra, its homologue in escherichia coli, control many phenotypic traits, such as motility and pathogenesis in erwinia species, glycogen biosynthesis, cell size and biofilm formation ... | 2003 | 12488561 |
| oxyr acts as a repressor of catalase expression in neisseria gonorrhoeae. | it has been reported that neisseria gonorrhoeae possesses a very high level of catalase activity, but the regulation of catalase expression has not been investigated extensively. in escherichia coli and salmonella enterica serovar typhimurium, it has been demonstrated that oxyr is a positive regulator of hydrogen peroxide-inducible genes, including the gene encoding catalase. the oxyr gene from n. gonorrhoeae was cloned and used to complement an e. coli oxyr mutant, confirming its identity and f ... | 2003 | 12496210 |
| celi, a noncellulosomal family 9 enzyme from clostridium thermocellum, is a processive endoglucanase that degrades crystalline cellulose. | the family 9 cellulase gene celi of clostridium thermocellum, was previously cloned, expressed, and characterized (g. p. hazlewood, k. davidson, j. i. laurie, n. s. huskisson, and h. j. gilbert, j. gen. microbiol. 139:307-316, 1993). we have recloned and sequenced the entire celi gene and found that the published sequence contained a 53-bp deletion that generated a frameshift mutation, resulting in a truncated and modified c-terminal segment of the protein. the enzymatic properties of the wild-t ... | 2003 | 12511483 |
| functional and mutational analysis of conjugative transfer region 2 (tra2) from the inchi1 plasmid r27. | the transfer 2 region (tra2) of the conjugative plasmid drr27 (derepressed r27) was analyzed by psi-blast, insertional mutagenesis, genetic complementation, and an h-pilus assay. tra2 contains 11 mating-pair formation (mpf) genes that are essential for conjugative transfer, 9 of which are essential for h-pilus production (trha, -l, -e, -k, -b, -v, -c, -p, and -w). trhk has similarity to secretin proteins, suggesting a mechanism by which dna could traverse the outer membrane of donors. the remain ... | 2003 | 12511505 |
| a colonization factor (production of lateral flagella) of mesophilic aeromonas spp. is inactive in aeromonas salmonicida strains. | the nine laf (lateral flagellum) genes of mesophilic aeromonads are in the aeromonas salmonicida genome. the laf genes are functional, except for lafa (flagellin gene), which was inactivated by transposase 8 (is3 family). a pathogenic characteristic of mesophilic aeromonads (lateral flagella) is abolished in this specialized pathogen with a narrow host range. | 2003 | 12514057 |
| nitric oxide contributes to induction of innate immune responses to gram-negative bacteria in drosophila. | studies in mammals uncovered important signaling roles of nitric oxide (no), and contributions to innate immunity. suggestions of conservation led us to explore the involvement of no in drosophila innate immunity. inhibition of nitric oxide synthase (nos) increased larval sensitivity to gram-negative bacterial infection, and abrogated induction of the antimicrobial peptide diptericin. nos was up-regulated after infection. antimicrobial peptide reporters revealed that no triggered an immune respo ... | 2003 | 12514104 |
| [purification and properties of recombinant erwinia carotovora l-asparaginase expressed in e.coli cells]. | the method of purification erwinia carotovora recombinant l-asparaginase, expressed in e.coli, including ultrasonic disintegration of biomass, fractionation ammonium sulfate and column chromatography on cm- or sp-sepharose has been developed. according to sds-paage the enzyme preparation was homogeneous, its specific activity and yield consist respectively about 620 iu/mg of protein and 75%. physical-chemical and structural properties of recombinant erwinia carotovora l-asparaginase are similar ... | 2003 | 16119104 |
| polygalacturonase from sitophilus oryzae: possible horizontal transfer of a pectinase gene from fungi to weevils. | endo-polygalacturonase, one of the group of enzymes known collectively as pectinases, is widely distributed in bacteria, plants and fungi. the enzyme has also been found in several weevil species and a few other insects, such as aphids, but not in drosophila melanogaster, anopheles gambiae, or caenorhabditis elegans or, as far as is known, in any more primitive animal species. what, then, is the genetic origin of the polygalacturonases in weevils? since some weevil species harbor symbiotic micro ... | 2003 | 15841240 |
| [expression of gene aiia carrying the promoter of gene cry3aa in bacillus thuringiensis]. | n-acyl-homoserine lactones (ahls), are widely conserved signal molecules present in quorum-sensing systems of many gram-negative bacteria. ahls molecules mediate the expression of virulence genes of a range of bacterial pathogens. recently, it has been reported that aiia protein, which widely exists in bacillus species, can inactivate the ahls by hydrolyzing the lactone bond of ahls, thus attenuate the diseases caused by the expression of virulence genes of bacterial pathogens. bacillus thuringi ... | 2003 | 15969053 |
| structure of the o-polysaccharide of erwinia carotovora ssp. carotovora gspb 436. | the o-polysaccharide of a phytopathogenic bacterium, erwinia carotovora ssp. carotovora gspb 436, was studied by sugar and methylation analysis, along with 1h and 13c nmr spectroscopy. the following structure of the branched tetrasaccharide repeating unit of the o-polysaccharide was established: [carbohydrate structure in text] the o-polysaccharide contains a minor proportion of 4-o-methylrhamnose, which is suggested to terminate the polymer main chain. | 2003 | 14499581 |
| mechanism of pseudomonas aeruginosa rhlr transcriptional regulation of the rhlab promoter. | pseudomonas aeruginosa contains two transcription regulators (lasr and rhlr) that, when complexed with their specific autoinducers (3-oxo-dodecanoyl-homoserine lactone and butanoyl-homoserine lactone, respectively) activate transcription of different virulence-associated traits. we studied the rhlr-dependent transcriptional regulation of the rhlab operon encoding rhamnosyltransferase 1, an enzyme involved in the synthesis of the surfactant monorhamnolipid, and showed that rhlr binds to a specifi ... | 2003 | 14526008 |
| molecular characterization of brucella abortus chromosome ii recombination. | large-scale genomic rearrangements including inversions, deletions, and duplications are significant in bacterial evolution. the recently completed brucella melitensis 16m and brucella suis 1330 genomes have facilitated the investigation of such events in the brucella spp. suppressive subtractive hybridization (ssh) was employed in identifying genomic differences between b. melitensis 16m and brucella abortus 2308. analysis of 45 ssh clones revealed several deletions on chromosomes of b. abortus ... | 2003 | 14526025 |
| characterization of the hrp pathogenicity cluster of erwinia carotovora subsp. carotovora: high basal level expression in a mutant is associated with reduced virulence. | extracellularly targeted proteins are crucial for virulence of gram-negative phytopathogenic bacteria. erwinia carotovora subsp. carotovora employs the so-called type ii (gsp) pathway to secrete a number of pectinases and cellulases, which cause the typical tissue maceration symptoms of soft-rot disease. the type iii (hrp) pathway is the major virulence determinant in the genera pseudomonas, ralstonia and xanthomonas, and in non-macerating species of erwinia. the hrp cluster was recently partial ... | 2003 | 14576934 |
| high-resolution differentiation of cyanobacteria by using rrna-internal transcribed spacer denaturing gradient gel electrophoresis. | for many ecological studies of cyanobacteria, it is essential that closely related species or strains can be discriminated. since this is often not possible by using morphological features, cyanobacteria are frequently studied by using dna-based methods. a powerful method for analysis of the diversity and dynamics of microbial populations and for checking the purity and affiliation of cultivated strains is denaturing gradient gel electrophoresis (dgge). we realized high-resolution discrimination ... | 2003 | 14602623 |
| development and application of a dapb-based in vivo expression technology system to study colonization of rice by the endophytic nitrogen-fixing bacterium pseudomonas stutzeri a15. | pseudomonas stutzeri a15 is a nitrogen-fixing bacterium isolated from paddy rice. strain a15 is able to colonize and infect rice roots. this strain may provide rice plants with fixed nitrogen and hence promote plant growth. in this article, we describe the use of dapb-based in vivo expression technology to identify p. stutzeri a15 genes that are specifically induced during colonization and infection (cii). we focused on the identification of p. stutzeri a15 genes that are switched on during rice ... | 2003 | 14602651 |
| host specificity of mollicutes oric plasmids: functional analysis of replication origin. | recently, artificial oric plasmids containing the chromosomal dnaa gene and surrounding dnaa box sequences were obtained for the mollicutes spiroplasma citri and mycoplasma pulmonis. in order to study the specificity of these plasmids among mollicutes, a set of similar oric plasmids was developed for three mycoplasmas belonging to the mycoides cluster, mycoplasma mycoides subsp. mycoides lc (mmmlc), m.mycoides subsp. mycoides sc (mmmsc) and mycoplasma capricolum subsp. capricolum. mycoplasmas fr ... | 2003 | 14602921 |
| use of o-antigen gene cluster-specific pcrs for the identification and o-genotyping of yersinia pseudotuberculosis and yersinia pestis. | yersinia pestis is a very recently evolved clone of yersinia pseudotuberculosis serotype o:1b. this close relationship causes potential difficulties in dna-based diagnostic methods. analysis of the o-antigen gene clusters in these two organisms identified two regions that were used to specifically identify y. pestis-y. pseudotuberculosis as a group or y. pestis alone. both pcr assays were found to be 100% specific when tested on a large collection of yersinia species and other enterobacteriaceae ... | 2003 | 14605146 |
| the pmra-pmrb two-component system responding to acidic ph and iron controls virulence in the plant pathogen erwinia carotovora ssp. carotovora. | efficient response to environmental cues is crucial to successful infection by plant-pathogenic bacteria such as erwinia carotovora ssp. carotovora. the expression of the main virulence genes of this pathogen, encoding extracellular enzymes that degrade the plant-cell wall, is subject to complex regulatory machinery where two-component systems play an important role. in this paper, we describe for the first time the involvement of the pmra-pmrb two-component system in regulation of virulence in ... | 2003 | 14617142 |
| the quorum sensing negative regulators esar and expr(ecc), homologues within the luxr family, retain the ability to function as activators of transcription. | most luxr homologues function as activators of transcription during the process of quorum sensing, but a few, including esar and expr(ecc), negatively impact gene expression. the luxr-activated luxi promoter and luxr binding site, the lux box, were used in artificial contexts to assess the potential for transcriptional activation and dna binding by esar and expr(ecc). although the acyl-homoserine lactone responsiveness of both proteins is the opposite of that shown by most luxr family members, e ... | 2003 | 14617666 |
| isolation of enterobacter sakazakii from midgut of stomoxys calcitrans. | 2003 | 14626227 | |
| regulation of lysine biosynthesis and transport genes in bacteria: yet another rna riboswitch? | comparative analysis of genes, operons and regulatory elements was applied to the lysine biosynthetic pathway in available bacterial genomes. we report identification of a lysine-specific rna element, named the lys element, in the regulatory regions of bacterial genes involved in biosynthesis and transport of lysine. similarly to the previously described rna regulatory elements for three vitamins (riboflavin, thiamin and cobalamin), purine and methionine regulons, this regulatory rna structure i ... | 2003 | 14627808 |
| functional domains of the rhlr transcriptional regulator of pseudomonas aeruginosa. | the rhlr transcriptional regulator of pseudomonas aeruginosa, along with its cognate autoinducer, n-butyryl homoserine lactone (c(4)-hsl), regulates gene expression in response to cell density. with an escherichia coli lexa-based protein interaction system, we demonstrated that rhlr multimerized and that the degree of multimerization was dependent on the c(4)-hsl concentration. studies with an e. coli lasb::lacz lysogen demonstrated that rhlr multimerization was necessary for it to function as a ... | 2003 | 14645272 |
| gaca regulates symbiotic colonization traits of vibrio fischeri and facilitates a beneficial association with an animal host. | the gacs/gaca two-component system regulates the expression of bacterial traits during host association. although the importance of gacs/gaca as a regulator of virulence is well established, its role in benign associations is not clear, as mutations in either the gacs or gaca gene have little impact on the success of colonization in nonpathogenic associations studied thus far. using as a model the symbiotic association of the bioluminescent marine bacterium vibrio fischeri with its animal host, ... | 2003 | 14645281 |
| pathways leading from bara/sira to motility and virulence gene expression in salmonella. | the bara and sira genes of salmonella enterica serovar typhimurium encode a two-component sensor kinase and a response regulator, respectively. this system increases the expression of virulence genes and decreases the expression of motility genes. in this study, we examined the pathways by which sira affects these genes. we found that the master regulator of flagellar genes, flhdc, had a positive regulatory effect on the primary regulator of intestinal virulence determinants, hila, but that hila ... | 2003 | 14645287 |
| oxidative burst elicited by bacillus mycoides isolate bac j, a biological control agent, occurs independently of hypersensitive cell death in sugar beet. | response of sugar beet cultivars c40 and ush11 to syringe infiltration of live and dead bacillus mycoides isolate bac j, a biological control agent, and virulent and avirulent isolates of erwinia carotovora pv. betavasculorum was measured by monitoring systemic acquired resistance control of cercospora beticola, specific activity of chitinase and beta-glucanase, the oxidative burst, and hypersensitive cell death at the infiltration site. priming sugar beet with b. mycoides bac j (1 x 10(8) cells ... | 2003 | 14651348 |
| quorum sensing in nitrogen-fixing rhizobia. | members of the rhizobia are distinguished for their ability to establish a nitrogen-fixing symbiosis with leguminous plants. while many details of this relationship remain a mystery, much effort has gone into elucidating the mechanisms governing bacterium-host recognition and the events leading to symbiosis. several signal molecules, including plant-produced flavonoids and bacterially produced nodulation factors and exopolysaccharides, are known to function in the molecular conversation between ... | 2003 | 14665677 |
| an oligonucleotide array for the identification and differentiation of bacteria pathogenic on potato. | abstract oligonucleotides, 16 to 24 bases long, were selected from the 3' end of the 16s gene and the 16s-23s intergenic spacer regions of bacteria pathogenic on potato, including clavibacter michiganensis subsp. sepedonicus, ralstonia solanacearum, and the pectolytic erwinias, including erwinia carotovora subsp. atroseptica and carotovora and e. chrysanthemi. oligonucleotides were designed and formatted into an array by pin spotting on nylon membranes. genomic dna from bacterial cultures was am ... | 2003 | 18944335 |
| ethylene-insensitive tobacco shows differentially altered susceptibility to different pathogens. | abstract transgenic tobacco plants (tetr) expressing the mutant etr1-1 gene from arabidopsis thaliana are insensitive to ethylene and develop symptoms of wilting and stem rot when grown in nonautoclaved soil. several isolates of fusarium, thielaviopsis, and pythium were recovered from stems of diseased tetr plants. inoculation with each of these isolates of 6-week-old plants growing in autoclaved soil caused disease in tetr plants but not in nontransformed plants. also, when 2-week-old seedlings ... | 2003 | 18943162 |
| degradation of pathogen quorum-sensing molecules by soil bacteria: a preventive and curative biological control mechanism. | abstract the plasmid pme6863, carrying the aiia gene from the soil bacterium bacillus sp. a24 that encodes a lactonase enzyme able to degrade n-acyl-homoserine lactones (ahls), was introduced into the rhizosphere isolate pseudomonas fluorescens p3. this strain is not an effective biological control agent against plant pathogens. the transformant p. fluorescens p3/pme6863 acquired the ability to degrade ahls. in planta, p. fluorescens p3/pme6863 significantly reduced potato soft rot caused by erw ... | 2003 | 19719608 |
| npdr, a repressor involved in 2,4,6-trinitrophenol degradation in rhodococcus opacus hl pm-1. | rhodococcus opacus hl pm-1 utilizes 2,4,6-trinitrophenol (picric acid) as a sole nitrogen source. the initial attack on picric acid occurs through two hydrogenation reactions. hydride transferase ii (encoded by npdi) and hydride transferase i (encoded by npdc) are responsible for the hydride transfers. database searches with the npd genes have indicated the presence of a putative transcriptional regulator, npdr. here, the npdr gene was expressed in escherichia coli, and the protein was purified ... | 2004 | 14679229 |
| growth phase-dependent regulation and stringent control of fis are conserved processes in enteric bacteria and involve a single promoter (fis p) in escherichia coli. | the intracellular concentration of the escherichia coli factor for inversion stimulation (fis), a global regulator of transcription and a facilitator of certain site-specific dna recombination events, varies substantially in response to changes in the nutritional environment and growth phase. under conditions of nutritional upshift, fis is transiently expressed at very high levels, whereas under induced starvation conditions, fis is repressed by stringent control. we show that both of these regu ... | 2004 | 14679232 |
| legionella pneumophila type ii protein secretion promotes virulence in the a/j mouse model of legionnaires' disease pneumonia. | legionella pneumophila, the gram-negative agent of legionnaires' disease, possesses type iv pili and a type ii protein secretion (lsp) system, both of which are dependent upon the pild prepilin peptidase. by analyzing multiple pild mutants and various types of lsp mutants as well as performing trans-complementation of these mutants, we have confirmed that pild and type ii secretion genes are required for l. pneumophila infection of both amoebae and human macrophages. based upon a complete analys ... | 2004 | 14688110 |
| plant er genes that encode photorespiratory enzymes confer resistance against disease. | downy mildew caused by the oomycete pathogen pseudoperonospora cubensis is a devastating foliar disease of cucurbits worldwide. we previously demonstrated that the wild melon line pi 124111f (pi) is highly resistant to all pathotypes of p. cubensis. that resistance was controlled genetically by two partially dominant, complementary loci. here, we show that unlike other plant disease resistance genes, which confer an ability to resist infection by pathogens expressing corresponding avirulence gen ... | 2004 | 14688292 |
| complete sequence and evolutionary genomic analysis of the pseudomonas aeruginosa transposable bacteriophage d3112. | bacteriophage d3112 represents one of two distinct groups of transposable phage found in the clinically relevant, opportunistic pathogen pseudomonas aeruginosa. to further our understanding of transposable phage in p. aeruginosa, we have sequenced the complete genome of d3112. the genome is 37,611 bp, with an overall g+c content of 65%. we have identified 53 potential open reading frames, including three genes (the c repressor gene and early genes a and b) that have been previously characterized ... | 2004 | 14702309 |
| an evolutionary hot spot: the pngr234b replicon of rhizobium sp. strain ngr234. | rhizobium sp. strain ngr234 has an exceptionally broad host range and is able to nodulate more than 112 genera of legumes. since the overall organization of the ngr234 genome is strikingly similar to that of the narrow-host-range symbiont rhizobium meliloti strain 1021 (also known as sinorhizobium meliloti), the obvious question is why are the spectra of hosts so different? study of the early symbiotic genes of both bacteria (carried by the syma plasmids) did not provide obvious answers. yet, bo ... | 2004 | 14702322 |
| bacterial expression of a human monoclonal antibody-alkaline phosphatase conjugate specific for entamoeba histolytica. | we previously produced human monoclonal antibody fab fragments specific to entamoeba histolytica in escherichia coli. in order to use these fab fragments for diagnostic purposes, an expression vector to produce a fusion protein of fab and alkaline phosphatase (phoa) in e. coli was designed and constructed. the e. coli phoa gene was fused to the 3' terminus of the gene encoding the heavy-chain fd region. the kappa and fd genes from a previously prepared antibody clone, cp33, which is specific for ... | 2004 | 14715571 |
| parasite-specific immune response in adult drosophila melanogaster: a genomic study. | insects of the order diptera are vectors for parasitic diseases such as malaria, sleeping sickness and leishmania. in the search for genes encoding proteins involved in the antiparasitic response, we have used the protozoan parasite octosporea muscaedomesticae for oral infections of adult drosophila melanogaster. to identify parasite-specific response molecules, other flies were exposed to virus, bacteria or fungi in parallel. analysis of gene expression patterns after 24 h of microbial challeng ... | 2004 | 14749722 |
| integration of environmental and host-derived signals with quorum sensing during plant-microbe interactions. | many plant-associated microbes use secreted autoinducer molecules, including n-acylhomoserine lactones (ahls), to regulate diverse behaviours in association with their population density (quorum sensing). often, these responses are affected by environmental conditions, including the presence of other ahl-producing bacterial species. in addition, plant-derived metabolites, including products that arise as a direct result of the bacterial infection, may profoundly influence ahl-regulated behaviour ... | 2004 | 14764105 |
| norm, an erwinia amylovora multidrug efflux pump involved in in vitro competition with other epiphytic bacteria. | blossoms are important sites of infection for erwinia amylovora, the causal agent of fire blight of rosaceous plants. before entering the tissue, the pathogen colonizes the stigmatic surface and has to compete for space and nutrient resources within the epiphytic community. several epiphytes are capable of synthesizing antibiotics with which they antagonize phytopathogenic bacteria. here, we report that a multidrug efflux transporter, designated norm, of e. amylovora confers tolerance to the tox ... | 2004 | 14766544 |
| insecticidal bacillus thuringiensis silences erwinia carotovora virulence by a new form of microbial antagonism, signal interference. | it is commonly known that bacteria may produce antibiotics to interfere with the normal biological functions of their competitors in order to gain competitive advantages. here we report that bacillus thuringiensis suppressed the quorum-sensing-dependent virulence of plant pathogen erwinia carotovora through a new form of microbial antagonism, signal interference. e. carotovora produces and responds to acyl-homoserine lactone (ahl) quorum-sensing signals to regulate antibiotic production and expr ... | 2004 | 14766576 |
| evaluation of colilert-18 for detection of coliforms and eschericha coli in subtropical freshwater. | the accuracy of colilert-18 as a test for coliforms and escherichia coli in subtropical freshwater was evaluated by using api 20e strips and fatty acid methyl ester analysis. the false-positive and -negative rates of detection were 7.4 and 3.5%, respectively, for e. coli and 9.6 and 6.3%, respectively, for coliforms. | 2004 | 14766614 |
| microbial transformation of pyrethroid insecticides in aqueous and sediment phases. | recent studies showed that synthetic pyrethroids (sps) can move via surface runoff into aquatic systems. fifty-six of sp-degrading bacteria strains were isolated from contaminated sediments, of which six were evaluated for their ability to transform bifenthrin and permethrin in the aqueous phase and bifenthrin in the sediment phase. in the aqueous phase, bifenthrin was rapidly degraded by strains of stenotrophomonas acidaminiphila, and the half-life (t1/2) was reduced from >700 h to 30 to 131 h. ... | 2004 | 14768859 |
| degradation of acyl-homoserine lactone molecules by acinetobacter sp. strain c1010. | a bacterium c1010, isolated from the rhizospheres of cucumbers in fields in korea, degraded the microbial quorum-sensing molecules, hexanoyl homoserine lactone (hhsl), and octadecanoyl homoserine lactone (ohsl). morphological characteristics and 16s rrna sequence analysis identified c1010 as acinetobacter sp. strain c1010. this strain was able to degrade the acyl-homoserine lactones (ahls) produced by the biocontrol bacterium, pseudomonas chlororaphis o6, and a phytopathogenic bacterium, burkhol ... | 2004 | 15644910 |
| use of 1,4-naphthoquinones for control of erwinia carotovora. | the antimicrobial effect of 5 naphthoquinones was tested against the phytopathogenic bacteria erwinia carotovora. disk diffusion tests and determination of minimal inhibitory concentrations (mic) indicate that the compound naphthazarin (ntz) has the best antibacterial activity among the naphthoquinones tested. studies on the mode of action indicate the effect of ntz was bactericidal at 10 microg/ml. when cultivation was done in the presence of sodium ascorbate, the restoration of e. carotovora g ... | 2004 | 15644912 |
| sensitive and specific detection of xanthomonas campestris pv campestris by pcr using species-specific primers based on hrpf gene sequences. | a sensitive and specific assay was developed to detect bacterial black rot of crucifers caused by xanthomonas campestris pv. campestris (x. c. pv. campestris), in cabbage seed and plant. primers xcf and xcr from hrpf homologous to nolx, host recognition protein, were used to amplify a 525 bp dna fragment. pcr technique was applied to detect the pathogen in naturally infected seed and plant of cabbage. the pcr product was only produced from x. c. pv. campestris among 40 isolates of xanthomonas st ... | 2004 | 15646387 |
| potential ecotoxicological implication of methyl tert-butyl ether (mtbe) spills in the environment. | streptomyceticidal activity of methyl tert-butyl ether (mtbe) elucidated for the first time. adverse effect of mtbe, the gasoline additive, against 11 soil inhabitant streptomyces spp. isolates was investigated. mtbe, an octane enhancer is added to gasoline to reduce atmospheric concentrations of carbon monoxide and ozone. it contaminates soil and groundwater by fuel leaks and spills. streptomyces spp. are of the major contributors to the biological buffering of soils by exerting beneficial and ... | 2004 | 15673212 |
| characterization of atypical erwinia carotovora strains causing blackleg of potato in brazil. | to determine the characteristics of bacteria associated with the blackleg disease of potato in brazil and compare them with species and subspecies of pectolytic erwinia. | 2004 | 14962133 |
| antifungal activity of beta-asarone from rhizomes of acorus gramineus. | an antifungal substance was isolated from the extract of acorus gramineus using various chromatographic procedures. the antibiotic was identified as beta-asarone, cis-2,4,5-trimethoxy-1-propenylbenzene, on the basis of the high-resolution ei-mass, nmr, and uv spectral data. beta-asarone completely inhibited mycelial growth of some plant pathogenic fungi, cladosporium cucumerinum,colletotrichum orbiculare, magnaporthe grisea, and pythium ultimum, in a range of 0.5-30 microg/ml. the growth of baci ... | 2004 | 14969530 |
| inactivation of a pseudomonas aeruginosa quorum-sensing signal by human airway epithelia. | mammalian airways protect themselves from bacterial infection by using multiple defense mechanisms including antimicrobial peptides, mucociliary clearance, and phagocytic cells. we asked whether airways might also target a key bacterial cell-cell communication system, quorum-sensing. the opportunistic pathogen pseudomonas aeruginosa uses two quorum-sensing molecules, n-(3-oxododecanoyl)-l-homoserine lactone (3oc12-hsl) and n-butanoyl-l-homoserine lactone (c4-hsl), to control production of extrac ... | 2004 | 14970327 |
| bacterial volatiles induce systemic resistance in arabidopsis. | plant growth-promoting rhizobacteria, in association with plant roots, can trigger induced systemic resistance (isr). considering that low-molecular weight volatile hormone analogues such as methyl jasmonate and methyl salicylate can trigger defense responses in plants, we examined whether volatile organic compounds (vocs) associated with rhizobacteria can initiate isr. in arabidopsis seedlings exposed to bacterial volatile blends from bacillus subtilis gb03 and bacillus amyloliquefaciens in937a ... | 2004 | 14976231 |
| one-step purification and kinetic properties of the recombinant l-asparaginase from erwinia carotovora. | ecar-lans, the recombinant l-asparaginase from erwinia carotovora, is a prospective therapeutic enzyme for leukaemia treatment. an efficient and economical scheme was developed for the purification, cloning and expression in eschericha coli of ecar-lans. more than 90% purity, complemented with 72% active enzyme recovery, was achieved with a single chromatographic purification step. the activity of purified l-asparaginase was 630 i.u./mg. the ecar-lans k (m) value was 98x10(-6) m for the main phy ... | 2004 | 15032742 |
| thermodependence of growth and enzymatic activities implicated in pathogenicity of two erwinia carotovora subspecies (pectobacterium spp.). | erwinia carotovora subsp. atroseptica and erwinia carotovora subsp. carotovora can cause substantial damage to economically important plant crops and stored products. the occurrence of the disease and the scale of the damage are temperature dependent. disease development consists first of active multiplication of the bacteria in the infection area and then production of numerous extracellular enzymes. we investigated the effects of various temperatures on these two steps. we assayed the specific ... | 2004 | 15052318 |
| genetic evidence that legionella pneumophila rpos modulates expression of the transmission phenotype in both the exponential phase and the stationary phase. | the opportunistic pathogen legionella pneumophila alternates between two states: replication within phagocytes and transmission between host amoebae or macrophages. in broth cultures that model this life cycle, during the replication period, csra inhibits expression of transmission traits. when nutrients become limiting, the alarmone (p)ppgpp accumulates and the sigma factors rpos and flia and the positive activators leta/s and lete promote differentiation to the transmissible form. here we show ... | 2004 | 15102753 |
| luxs is required for persistent pneumococcal carriage and expression of virulence and biosynthesis genes. | streptococcus pneumoniae causes several diseases, including otitis media, pneumonia, and meningitis. although little is known about the regulation of or how individual pneumococcal factors contribute to these disease states, there is evidence suggesting that some factors are regulated by a cell-density-dependent mechanism (quorum sensing). quorum sensing allows bacteria to couple transcription with changes in cell density; bacteria achieve this by sensing and responding to small diffusible signa ... | 2004 | 15102809 |
| the plant virus tomato spotted wilt tospovirus activates the immune system of its main insect vector, frankliniella occidentalis. | tospoviruses have the ability to infect plants and their insect vectors. tomato spotted wilt virus (tswv), the type species in the tospovirus genus, infects its most important insect vector, frankliniella occidentalis, the western flower thrips (wft). however, no detrimental effects on the life cycle or cytopathological changes have been reported in the wft after tswv infection, and relatively few viral particles can be observed even several days after infection. we hypothesized that tswv infect ... | 2004 | 15113877 |
| positive control of swarming, rhamnolipid synthesis, and lipase production by the posttranscriptional rsma/rsmz system in pseudomonas aeruginosa pao1. | in pseudomonas aeruginosa, the small rna-binding, regulatory protein rsma is a negative control element in the formation of several extracellular products (e.g., pyocyanin, hydrogen cyanide, pa-il lectin) as well as in the production of n-acylhomoserine lactone quorum-sensing signal molecules. rsma was found to control positively the ability to swarm and to produce extracellular rhamnolipids and lipase, i.e., functions contributing to niche colonization by p. aeruginosa. an rsma null mutant was ... | 2004 | 15126453 |
| genomic diversity of erwinia carotovora subsp. carotovora and its correlation with virulence. | we used genetic and biochemical methods to examine the genomic diversity of the enterobacterial plant pathogen erwinia carotovora subsp. carotovora. the results obtained with each method showed that e. carotovora subsp. carotovora strains isolated from one ecological niche, potato plants, are surprisingly diverse compared to related pathogens. a comparison of 23 partial mdh sequences revealed a maximum pairwise difference of 10.49% and an average pairwise difference of 2.13%, values which are mu ... | 2004 | 15128563 |