Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| the pspa protein of escherichia coli is a negative regulator of sigma(54)-dependent transcription. | in eubacteria, expression of genes transcribed by an rna polymerase holoenzyme containing the alternate sigma factor sigma(54) is positively regulated by proteins belonging to the family of enhancer-binding proteins (ebps). these proteins bind to upstream activation sequences and are required for the initiation of transcription at the sigma(54)-dependent promoters. they are typically inactive until modified in their n-terminal regulatory domain either by specific phosphorylation or by the bindin ... | 2000 | 10629175 |
| helicobacter pylori uptake and efflux: basis for intrinsic susceptibility to antibiotics in vitro. | we previously demonstrated (m. m. exner, p. doig, t. j. trust, and r. e. w. hancock, infect. immun. 63:1567-1572, 1995) that helicobacter pylori has at least one nonspecific porin, hope, which has a low abundance in the outer membrane but forms large channels. h. pylori is relatively susceptible to most antimicrobial agents but less susceptible to the polycationic antibiotic polymyxin b. we demonstrate here that h. pylori is able to take up higher basal levels of the hydrophobic fluorescent prob ... | 2000 | 10639345 |
| isolation of neisseria gonorrhoeae mutants that show enhanced trafficking across polarized t84 epithelial monolayers. | initiation of a gonococcal infection involves attachment of neisseria gonorrhoeae to the plasma membrane of an epithelial cell in the mucosal epithelium and its internalization, transepithelial trafficking, and exocytosis from the basal membrane. piliation and expression of certain opa proteins and the immunoglobulin a1 protease influence the transcytosis process. we are interested in identifying other genetic determinants of n. gonorrhoeae that play a role in transcellular trafficking. using po ... | 2000 | 10639460 |
| crc is involved in catabolite repression control of the bkd operons of pseudomonas putida and pseudomonas aeruginosa. | crc (catabolite repression control) protein of pseudomonas aeruginosa has shown to be involved in carbon regulation of several pathways. in this study, the role of crc in catabolite repression control has been studied in pseudomonas putida. the bkd operons of p. putida and p. aeruginosa encode the inducible multienzyme complex branched-chain keto acid dehydrogenase, which is regulated in both species by catabolite repression. we report here that this effect is mediated in both species by crc. a ... | 2000 | 10648542 |
| bacterial cell surface display of an enzyme library for selective screening of improved cellulase variants. | the bacterial surface display method was used to selectively screen for improved variants of carboxymethyl cellulase (cmcase). a library of mutated cmcase genes generated by dna shuffling was fused to the ice nucleation protein (inp) gene so that the resulting fusion proteins would be displayed on the bacterial cell surface. some cells displaying mutant proteins grew more rapidly on carboxymethyl cellulose plates than controls, forming heterogeneous colonies. in contrast, cells displaying the no ... | 2000 | 10653752 |
| pathovars of pseudomonas syringae causing bacterial brown spot and halo blight in phaseolus vulgaris l. are distinguishable by ribotyping. | ribotyping was evaluated as a method to differentiate between pseudomonas syringae pv. phaseolicola and pv. syringae strains causing bacterial brown spot and halo blight diseases in phaseolus vulgaris l. ribotyping, with restriction enzymes bgli and sali and using the escherichia coli rrnb operon as the probe, differentiated 11 and 14 ribotypes, respectively, and a combination of data from both procedures yielded 19 combined ribotypes. cluster analysis of the combined ribotypes differentiated th ... | 2000 | 10653764 |
| arabidopsis thaliana eds4 contributes to salicylic acid (sa)-dependent expression of defense responses: evidence for inhibition of jasmonic acid signaling by sa. | the arabidopsis enhanced disease susceptibility 4 (eds4) mutation causes enhanced susceptibility to infection by the bacterial pathogen pseudomonas syringae pv. maculicola es4326 (psm es4326). gene-for-gene resistance to bacteria carrying the avirulence gene avrrpt2 is not significantly affected by eds4. plants homozygous for eds4 exhibit reduced expression of the pathogenesis-related gene pr-1 after infection by psm es4326, weakened responses to treatment with the signal molecule salicylic acid ... | 2000 | 10796016 |
| decreased inositol 1,4,5-trisphosphate content in pathogen-challenged soybean cells. | phosphoinositide-specific phospholipase c (pi-plc) has been shown to be transiently activated when plant cells were treated with elicitors. we thus investigated the activity of pi-plc when soybean cells were infected with the bacterial pathogen pseudomonas syringae pv. glycinea, by measuring cellular cytosolic inositol 1,4,5-trisphosphate (ip3) levels. we observed that ip3 content decreased in both compatible and incompatible interactions. in vitro phosphatase activities were similar in both wat ... | 2000 | 10796022 |
| avrpto enhances growth and necrosis caused by pseudomonas syringae pv.tomato in tomato lines lacking either pto or prf. | avrpto was introduced into three tomato genotypes with two biotic agents to study its role in compatible interactions. avrpto enhanced the capacity of the pseudomonas syringae pv. tomato strain t1 to induce necrotic symptoms on tomato plants that lacked either pto or prf genes. the enhanced necrosis correlated with a small increase in bacterial growth. in planta expression of avrpto in isolation did not elicit necrosis in the absence of a functional prf gene. | 2000 | 10796023 |
| ethylene formation and phenotypic analysis of transgenic tobacco plants expressing a bacterial ethylene-forming enzyme. | a bacterial ethylene-forming enzyme (efe) catalyzes oxygenation of 2-oxoglutarate to produce ethylene and carbon dioxide in contrast to a plant enzyme which uses 1-aminocyclopropane-1-carboxylic acid as a substrate. we constructed several lines of transgenic tobacco plants which expressed an efe from pseudomonas syringae pv. phaseolicola pk2. the gene encoding a chimeric protein consisting of efe and beta-glucuronidase (gus) was introduced into the tobacco genome using a binary vector which dire ... | 2000 | 10805596 |
| response to xanthomonas campestris pv. vesicatoria in tomato involves regulation of ethylene receptor gene expression. | although ethylene regulates a wide range of defense-related genes, its role in plant defense varies greatly among different plant-microbe interactions. we compared ethylene's role in plant response to virulent and avirulent strains of xanthomonas campestris pv. vesicatoria in tomato (lycopersicon esculentum mill.). the ethylene-insensitive never ripe (nr) mutant displays increased tolerance to the virulent strain, while maintaining resistance to the avirulent strain. expression of the ethylene r ... | 2000 | 10806227 |
| differential regulation of plastidial and cytosolic isoforms of peptide methionine sulfoxide reductase in arabidopsis. | we report the characterization of two members of a gene family from arabidopsis that encode, respectively, cytosolic (cpmsr) and plastid-targeted (ppmsr) isoforms of the oxidative-stress-repair enzyme peptide methionine sulfoxide reductase. overexpression of these proteins in escherichia coli confirmed that each had pmsr enzyme activity with a synthetic substrate, n-acetyl-[(3)h]-methionine sulfoxide, or a biological substrate, alpha-1 proteinase inhibitor. the ppmsr was imported into intact chl ... | 2000 | 10806242 |
| cloning and expression of ntnd, encoding a novel nad(p)(+)-independent 4-nitrobenzyl alcohol dehydrogenase from pseudomonas sp. strain tw3. | pseudomonas sp. strain tw3 is able to metabolize 4-nitrotoluene to 4-nitrobenzoate and toluene to benzoate aerobically via a route analogous to the upper pathway of the tol plasmids. we report the cloning and characterization of a benzyl alcohol dehydrogenase gene (ntnd) which encodes the enzyme for the catabolism of 4-nitrobenzyl alcohol and benzyl alcohol to 4-nitrobenzaldehyde and benzaldehyde, respectively. the gene is located downstream of the previously reported ntn gene cluster. ntnd bear ... | 2000 | 10809692 |
| members of the arabidopsis hrt/rpp8 family of resistance genes confer resistance to both viral and oomycete pathogens. | turnip crinkle virus (tcv) inoculation onto tcv-resistant arabidopsis leads to a hypersensitive response (hr) controlled by the dominant gene hrt. hrt is a member of the class of resistance (r) genes that contain a leucine zipper, a nucleotide binding site, and leucine-rich repeats. the chromosomal position of hrt and its homology to resistance gene rpp8 and two rpp8 homologs indicate that unequal crossing over and gene conversion may have contributed to hrt evolution. rpp8 confers resistance to ... | 2000 | 10810142 |
| pti4 is induced by ethylene and salicylic acid, and its product is phosphorylated by the pto kinase. | the tomato pti4 gene encodes a transcription factor that was identified on the basis of its specific interaction with the product of the pto disease resistance gene in a yeast two-hybrid system. we show here that the pti4 protein specifically binds the gcc-box cis element, which is present in the promoter region of many pathogenesis-related (pr) genes. expression of the pti4 gene in tomato leaves was rapidly induced by ethylene and by infection with pseudomonas syringae pv tomato, and this induc ... | 2000 | 10810149 |
| pilus formation and protein secretion by the same machinery in escherichia coli. | the secreton (type ii secretion) and type iv pilus biogenesis branches of the general secretory pathway in gram-negative bacteria share many features that suggest a common evolutionary origin. five components of the secreton, the pseudopilins, are similar to subunits of type iv pili. here, we report that when the 15 genes encoding the pullulanase secreton of klebsiella oxytoca were expressed on a high copy number plasmid in escherichia coli, one pseudopilin, pulg, was assembled into pilus-like b ... | 2000 | 10811613 |
| thr38 and ser198 are pto autophosphorylation sites required for the avrpto-pto-mediated hypersensitive response. | the tomato pto kinase confers resistance to pseudomonas syringae pv. tomato expressing the avrpto protein. to elucidate the role of pto autophosphorylation in disease resistance, eight sites autophosphorylated by pto in vitro were identified by a combination of hplc purification of tryptic phosphopeptides, maldi-tof/ms analysis and edman degradation. mutational analysis of the autophosphorylation sites revealed that pto residues thr38 and ser198 are required for avrpto-pto- mediated elicitation ... | 2000 | 10811617 |
| a bacterial sensor of plant cell contact controls the transcriptional induction of ralstonia solanacearum pathogenicity genes. | the hrp genes of the plant pathogen ralstonia solanacearum are key pathogenicity determinants; they encode a type iii protein secretion machinery involved in the secretion of mediators of the bacterium-plant interaction. these hrp genes are under the genetic control of the hrpb regulatory gene, expression of which is induced when bacteria are co-cultivated with plant cell suspensions. in this study, we used hrp-gfp transcriptional fusions to demonstrate that the expression of the hrpb and type i ... | 2000 | 10811621 |
| eukaryotic fatty acylation drives plasma membrane targeting and enhances function of several type iii effector proteins from pseudomonas syringae. | bacterial pathogens of plants and animals utilize conserved type iii delivery systems to traffic effector proteins into host cells. plant innate immune systems evolved disease resistance (r) genes to recognize some type iii effectors, termed avirulence (avr) proteins. on disease-susceptible (r) plants, avr proteins can contribute to pathogen virulence. we demonstrate that several type iii effectors from pseudomonas syringae are targeted to the host plasma membrane and that efficient membrane ass ... | 2000 | 10830163 |
| a cluster of mutations disrupt the avirulence but not the virulence function of avrpto. | avrpto in pseudomonas syringae pv. tomato encodes an avirulence protein that triggers race-specific resistance in tomato plants carrying pto. the avrpto protein is secreted from p. syringae pv. tomato to plant cells through the type iii secretion pathway and activates race-specific resistance by a direct interaction with the pto protein. here we report that avrpto enhances the virulence of p. syringae pv. tomato in a strain-dependent manner in tomato plants lacking pto. to determine whether the ... | 2000 | 10830258 |
| prey range characterization, ribotyping, and diversity of soil and rhizosphere bdellovibrio spp. isolated on phytopathogenic bacteria. | thirty new bdellovibrio strains were isolated from an agricultural soil and from the rhizosphere of plants grown in that soil. using a combined molecular and culture-based approach, we found that the soil bdellovibrios included subpopulations of organisms that differed from rhizosphere bdellovibrios. thirteen soil and seven common bean rhizosphere bdellovibrio strains were isolated when pseudomonas corrugata was used as prey; seven and two soil strains were isolated when erwinia carotovora subsp ... | 2000 | 10831412 |
| methods for intense aeration, growth, storage, and replication of bacterial strains in microtiter plates. | miniaturized growth systems for heterogeneous culture collections are not only attractive in reducing demands for incubation space and medium but also in making the parallel handling of large numbers of strains more practicable. we report here on the optimization of oxygen transfer rates in deep-well microtiter plates and the development of a replication system allowing the simultaneous and reproducible sampling of 96 frozen glycerol stock cultures while the remaining culture volume remains froz ... | 2000 | 10831450 |
| detection of pseudomonas savastanoi pv. savastanoi in olive plants by enrichment and pcr. | the sequence of the gene iaal of pseudomonas savastanoi ew2009 was used to design primers for pcr amplification. the iaal-derived primers directed the amplification of a 454-bp fragment from genomic dna isolated from 70 strains of p. savastanoi, whereas genomic dna from 93 non-p. savastanoi isolates did not yield this amplified product. a previous bacterial enrichment in the semiselective liquid medium pvf-1 improved the pcr sensitivity level, allowing detection of 10 to 100 cfu/ml of plant extr ... | 2000 | 10831456 |
| surface-displayed viral antigens on salmonella carrier vaccine. | we have developed a recombinant live oral vaccine using the ice-nucleation protein (inp) from pseudomonas syringae to display viral antigens on the surface of salmonella spp. fusion proteins containing viral antigens were expressed in the oral vaccine strain, salmonella typhi ty21a. surface localization was verified by immunoblotting and fluorescence-activated cell sorting. the immunogenicity of surface-displayed viral antigens on the recombinant live vaccine strain was assessed in mice inoculat ... | 2000 | 10835603 |
| isolation of the gene for eilp, an elicitor-inducible lrr receptor-like protein, from tobacco by differential display. | we screened tobacco genes, which are differentially expressed in response to a fungal elicitor, and have isolated a gene which codes for a leucine-rich repeat (lrr) protein closely related to cf genes in tomato. the eilp (elicitor inducible lrr protein) gene encodes 95 kda protein, which consists of a putative membrane spanning region, 28 leucine-rich repeats and some n-linked glycosylation sites, and shows high homology to cf-2/cf-5 family genes. southern blot analysis revealed the presence of ... | 2000 | 10845459 |
| a resistance gene product of the nucleotide binding site -- leucine rich repeats class can form a complex with bacterial avirulence proteins in vivo. | resistance (r) genes in plants mediate gene-for-gene disease resistance. the ligand-receptor model, which explains the gene-for-gene specificity, predicts a physical interaction between an elicitor, which is directly or indirectly encoded by an avirulence (avr) gene in the pathogen, and the corresponding r gene product. the nucleotide binding site (nbs) - leucine rich repeats (lrr) class of r genes is the largest known class of r genes. here we report that an nbs-lrr r protein and its cognate av ... | 2000 | 10849351 |
| identification of sinorhizobium meliloti genes regulated during symbiosis. | rna fingerprinting by arbitrarily primed pcr was used to isolate sinorhizobium meliloti genes regulated during the symbiotic interaction with alfalfa (medicago sativa). sixteen partial cdnas were isolated whose corresponding genes were differentially expressed between symbiotic and free-living conditions. thirteen sequences corresponded to genes up-regulated during symbiosis, whereas three were instead repressed during establishment of the symbiotic interaction. seven cdnas corresponded to known ... | 2000 | 10850975 |
| characterization of the fructosyltransferase gene of actinomyces naeslundii wvu45. | oral actinomycetes produce fructosyltransferase (ftf) enzymes which convert sucrose into polymers of d-fructose, known as levans, and these polymers are thought to contribute to the persistence and virulence of the organisms. a gene encoding ftf was isolated from actinomyces naeslundii wvu45; the deduced amino acid sequence showed significant similarity to known levansucrases of gram-negative environmental isolates but was less similar to ftfs from gram-positive bacteria. a transcriptional start ... | 2000 | 10850978 |
| marinomonas mediterranea mmb-1 transposon mutagenesis: isolation of a multipotent polyphenol oxidase mutant. | marinomonas mediterranea is a melanogenic marine bacterium expressing a multifunctional polyphenol oxidase (ppo) able to oxidize substrates characteristic for laccases and tyrosinases, as well as produce a classical tyrosinase. a new and quick method has been developed for screening laccase activity in culture plates to detect mutants differentially affected in this ppo activity. transposon mutagenesis has been applied for the first time to m. mediterranea by using different minitransposons load ... | 2000 | 10850991 |
| phosphorelay as the sole physiological route of signal transmission by the arc two-component system of escherichia coli. | the arc two-component system, comprising a tripartite sensor kinase (arcb) and a response regulator (arca), modulates the expression of numerous genes involved in respiratory functions. in this study, the steps of phosphoryl group transfer from phosphorylated arcb to arca were examined in vivo by using single copies of wild-type and mutant arcb alleles. the results indicate that the signal transmission occurs solely by his-asp-his-asp phosphorelay. | 2000 | 10851007 |
| virulence of the phytopathogen pseudomonas syringae pv. maculicola is rpon dependent. | we cloned the rpon (ntra and glnf) gene encoding sigma(54) from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. the p. syringae es4326 rpon gene complemented pseudomonas aeruginosa, escherichia coli, and klebsiella aerogenes rpon mutants for a variety of rpon mutant phenotypes, including the inability to utilize nitrate as sole nitrogen source. dna sequence analysis of the p. syringae es4326 rpon gene revealed that the deduced amino acid sequence was most similar (86% identi ... | 2000 | 10852883 |
| the alternative sigma factor rpon is required for hrp activity in pseudomonas syringae pv. maculicola and acts at the level of hrpl transcription. | beta-glucuronidase (uida) reporter gene fusions were constructed for the hrpz, hrpl, and hrps genes from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. these reporters, as well as an avrrpt2-uida fusion, were used to measure transcriptional activity in es4326 and a es4326 rpon mutant. rpon was required for the expression of avrrpt2, hrpz, and hrpl in vitro in minimal media and in vivo when infiltrated into arabidopsis thaliana leaves. in contrast, the expression of hrps was ... | 2000 | 10852884 |
| cdna-aflp reveals a striking overlap in race-specific resistance and wound response gene expression profiles. | the tomato cf-9 gene confers resistance to races of the fungal pathogen cladosporium fulvum expressing the avr9 gene. cdna amplified fragment length polymorphism analysis was used to display transcripts whose expression is rapidly altered during the avr9- and cf-9-mediated defense response in tobacco cell cultures. diphenyleneiodonium was used to abolish the production of active oxygen species during gene induction. of 30,000 fragments inspected, 290 showed altered abundance, of which 263 were i ... | 2000 | 10852940 |
| regulation of brucella abortus catalase. | all aerobic organisms have mechanisms that protect against oxidative compounds. catalase, peroxidase, superoxide dismutase, glutathione, and thioredoxin are widely distributed in many taxa and constitute elements of a nearly ubiquitous antioxidant metabolic strategy. interestingly, the regulatory mechanisms that control these elements are rather different depending on the nature of the oxidative stress and the organism. catalase is well documented to play an important role in protecting cells fr ... | 2000 | 10858195 |
| relationship between the tsh autotransporter and pathogenicity of avian escherichia coli and localization and analysis of the tsh genetic region. | the temperature-sensitive hemagglutinin tsh is a member of the autotransporter group of proteins and was first identified in avian-pathogenic escherichia coli (apec) strain chi7122. the prevalence of tsh was investigated in 300 e. coli isolates of avian origin and characterized for virulence in a 1-day-old chick lethality test. results indicate that among the tsh-positive apec isolates, 90.6% belonged to the highest virulence class. experimental inoculation of chickens with chi7122 and an isogen ... | 2000 | 10858231 |
| cytochrome p450-dependent metabolism of oxylipins in tomato. cloning and expression of allene oxide synthase and fatty acid hydroperoxide lyase. | allene oxide synthase (aos) and fatty acid hydroperoxide lyase (hpl) are plant-specific cytochrome p450s that commit fatty acid hydroperoxides to different branches of oxylipin metabolism. here we report the cloning and characterization of aos (leaos) and hpl (lehpl) cdnas from tomato (lycopersicon esculentum). functional expression of the cdnas in escherichia coli showed that leaos and lehpl encode enzymes that metabolize 13- but not 9-hydroperoxide derivatives of c(18) fatty acids. leaos was a ... | 2000 | 10859201 |
| a regulatory rna (prrb rna) modulates expression of secondary metabolite genes in pseudomonas fluorescens f113. | the gacs-gaca two-component signal transduction system, which is highly conserved in gram-negative bacteria, is required for the production of exoenzymes and secondary metabolites in pseudomonas spp. screening of a pseudomonas fluorescens f113 gene bank led to the isolation of a previously undefined locus which could restore secondary metabolite production to both gacs and gaca mutants of f113. sequence analysis of this locus demonstrated that it did not contain any obvious pseudomonas protein-c ... | 2000 | 10869066 |
| a new two-component regulatory system involved in adhesion, autolysis, and extracellular proteolytic activity of staphylococcus aureus. | a transposition mutant of staphylococcus aureus was selected from the parent strain mt23142, a derivative of strain 8325. the site of transposition was near the 5' terminus of the gene arls. arls exhibits strong similarities with histidine protein kinases. sequence analysis suggested that arls forms an operon with upstream gene arlr. the predicted product of arlr is a member of the ompr-phob family of response regulators. the arls mutant formed a biofilm on a polystyrene surface unlike the paren ... | 2000 | 10869073 |
| lon protease influences antibiotic production and uv tolerance of pseudomonas fluorescens pf-5. | pseudomonas fluorescens pf-5 is a soil bacterium that suppresses plant pathogens due in part to its production of the antibiotic pyoluteorin. previous characterization of pf-5 revealed three global regulators, including the stationary-phase sigma factor sigma(s) and the two-component regulators gaca and gacs, that influence both antibiotic production and stress response. in this report, we describe the serine protease lon as a fourth global regulator influencing these phenotypes in pf-5. lon mut ... | 2000 | 10877760 |
| genes expressed in pseudomonas putida during colonization of a plant-pathogenic fungus. | in vivo expression technology (ivet) was employed to study colonization of phytophthora parasitica by a biological control bacterium, pseudomonas putida 06909, based on a new selection marker. the pyrb gene, which encodes aspartate transcarbamoylase, an enzyme used for pyrimidine biosynthesis, was cloned from p. putida 06909. a pyrb-disrupted mutant did not grow in pyrimidine-deficient media unless it was complemented with pyrbc' behind an active promoter. thirty clones obtained from p. putida 0 ... | 2000 | 10877766 |
| characterization of an atrazine-degrading pseudaminobacter sp. isolated from canadian and french agricultural soils. | atrazine, a herbicide widely used in corn production, is a frequently detected groundwater contaminant. fourteen bacterial strains able to use this herbicide as a sole source of nitrogen were isolated from soils obtained from two farms in canada and two farms in france. these strains were indistinguishable from each other based on repetitive extragenic palindromic pcr genomic fingerprinting performed with primers eric1r, eric2, and boxa1r. based on 16s rrna sequence analysis of one representativ ... | 2000 | 10877767 |
| sequence analysis and initial characterization of two isozymes of hydroxylaminobenzene mutase from pseudomonas pseudoalcaligenes js45. | pseudomonas pseudoalcaligenes js45 grows on nitrobenzene by a partially reductive pathway in which the intermediate hydroxylaminobenzene is enzymatically rearranged to 2-aminophenol by hydroxylaminobenzene mutase (hab mutase). the properties of the enzyme, the reaction mechanism, and the evolutionary origin of the gene(s) encoding the enzyme are unknown. in this study, two open reading frames (haba and habb), each encoding an hab mutase enzyme, were cloned from a p. pseudoalcaligenes js45 genomi ... | 2000 | 10877793 |
| the common nodulation genes of astragalus sinicus rhizobia are conserved despite chromosomal diversity. | the nodulation genes of mesorhizobium sp. (astragalus sinicus) strain 7653r were cloned by functional complementation of sinorhizobium meliloti nod mutants. the common nod genes, nodd, noda, and nodbc, were identified by heterologous hybridization and sequence analysis. the noda gene was found to be separated from nodbc by approximately 22 kb and was divergently transcribed. the 2. 0-kb noddbc region was amplified by pcr from 24 rhizobial strains nodulating a. sinicus, which represented differen ... | 2000 | 10877796 |
| cultivar-specific avirulence and virulence functions assigned to avrpphf in pseudomonas syringae pv. phaseolicola, the cause of bean halo-blight disease. | the avrpphf gene was cloned from pseudomonas syringae pathovar phaseolicola (pph:) races 5 and 7, based on its ability to confer avirulence towards bean cultivars carrying the r1 gene for halo-blight resistance, such as red mexican. avrpphf comprised two open reading frames, which were both required for function, and was located on a 154 kb plasmid (pav511) in pph: strain rw60 of pph:, lacking pav511, displayed a loss in virulence to a range of previously susceptible cultivars such as tendergree ... | 2000 | 10880434 |
| applications of differential-display reverse transcription-pcr to molecular pathogenesis and medical mycology. | the host-fungus interaction is characterized by changes in gene expression in both host and pathogen. differential-display reverse transcription pcr (ddrt-pcr) is a pcr-based method that allows extensive analysis of gene expression among several cell populations. several limitations and drawbacks to this procedure have now been addressed, including the large number of false-positive results and the difficulty in confirming differential expression. modifications that simplify the reaction time, a ... | 2000 | 10885984 |
| female reproductive tissues are the primary target of agrobacterium-mediated transformation by the arabidopsis floral-dip method. | the floral-dip method for agrobacterium-mediated transformation of arabidopsis allows efficient plant transformation without need for tissue culture. to facilitate use with other plant species, we investigated the mechanisms that underlie this method. in manual outcrossing experiments, application of agrobacterium tumefaciens to pollen donor plants did not produce any transformed progeny, whereas application of agrobacterium to pollen recipient plants yielded transformants at a rate of 0.48%. ag ... | 2000 | 10889238 |
| enhancement of induced disease resistance by simultaneous activation of salicylate- and jasmonate-dependent defense pathways in arabidopsis thaliana. | the plant-signaling molecules salicylic acid (sa) and jasmonic acid (ja) play an important role in induced disease resistance pathways. cross-talk between sa- and ja-dependent pathways can result in inhibition of ja-mediated defense responses. we investigated possible antagonistic interactions between the sa-dependent systemic acquired resistance (sar) pathway, which is induced upon pathogen infection, and the ja-dependent induced systemic resistance (isr) pathway, which is triggered by nonpatho ... | 2000 | 10890883 |
| new substrates for the dicarboxylate transport system of sinorhizobium meliloti. | the dicarboxylate transport (dct) system of sinorhizobium meliloti, which is essential for a functional nitrogen-fixing symbiosis, has been thought to transport only dicarboxylic acids. we show here that the permease component of the dct system, dcta, can transport orotate, a monocarboxylic acid, with an apparent k(m) of 1.7 mm and a v(max) of 163 nmol min(-1) per mg of protein in induced cells. dcta was not induced by the presence of orotate. the transport of orotate was inhibited by several co ... | 2000 | 10894729 |
| the hypersensitive response facilitates plant infection by the necrotrophic pathogen botrytis cinerea. | plants have evolved efficient mechanisms to combat pathogen attack. one of the earliest responses to attempted pathogen attack is the generation of oxidative burst that can trigger hypersensitive cell death. this is called the hypersensitive response (hr) and is considered to be a major element of plant disease resistance. the hr is thought to deprive the pathogens of a supply of food and confine them to initial infection site. necrotrophic pathogens, such as the fungi botrytis cinerea and scler ... | 2000 | 10898976 |
| a unique 33-kd cysteine proteinase accumulates in response to larval feeding in maize genotypes resistant to fall armyworm and other lepidoptera. | plants respond to insect feeding with a number of defense mechanisms. using maize genotypes derived from antiquan germ plasm that are resistant to lepidoptera, we have demonstrated that a unique 33-kd cysteine proteinase accumulates in the whorl in response to larval feeding. the abundance of the proteinase increased dramatically at the site of larval feeding after 1 hr of infestation and continued to accumulate for as long as 7 days. the 33-kd cysteine proteinase was most abundant in the yellow ... | 2000 | 10899972 |
| the arabidopsis dnd1 "defense, no death" gene encodes a mutated cyclic nucleotide-gated ion channel. | gene-for-gene disease resistance typically includes a programmed cell death response known as the hypersensitive response (hr). the arabidopsis thaliana dnd1 mutant was previously isolated as a line that failed to produce the hr in response to avirulent pseudomonas syringae pathogens; plants homozygous for the recessive dnd1-1 mutation still carry out effective gene-for-gene resistance. the dnd1-1 mutation also causes constitutive systemic resistance and elevated levels of salicylic acid. in the ... | 2000 | 10900264 |
| ankb, a periplasmic ankyrin-like protein in pseudomonas aeruginosa, is required for optimal catalase b (katb) activity and resistance to hydrogen peroxide. | in this study, we have cloned the ankb gene, encoding an ankyrin-like protein in pseudomonas aeruginosa. the ankb gene is composed of 549 bp encoding a protein of 183 amino acids that possesses four 33-amino-acid ankyrin repeats that are a hallmark of erythrocyte and brain ankyrins. the location of ankb is 57 bp downstream of katb, encoding a hydrogen peroxide-inducible catalase, katb. monomeric ankb is a 19.4-kda protein with a pi of 5.5 that possesses 22 primarily hydrophobic amino acids at re ... | 2000 | 10913088 |
| controlling instability in gacs-gaca regulatory genes during inoculant production of pseudomonas fluorescens biocontrol strains. | secondary metabolism in fluorescent pseudomonads is globally regulated by gacs, which encodes a membrane-bound sensor kinase, and gaca, which encodes a transcriptional response regulator. spontaneous mutation in either gene blocked biosynthesis of the antimicrobial compounds hydrogen cyanide, 2,4-diacetylphloroglucinol, pyoluteorin, and pyrrolnitrin by the model biocontrol strain pseudomonas fluorescens cha0. spontaneous mutants also had altered abilities to utilize several carbon sources and to ... | 2000 | 10919762 |
| effect of starvation and the viable-but-nonculturable state on green fluorescent protein (gfp) fluorescence in gfp-tagged pseudomonas fluorescens a506. | the green fluorescent protein (gfp) gene, gfp, of the jellyfish aequorea victoria is being used as a reporter system for gene expression and as a marker for tracking prokaryotes and eukaryotes. cells that have been genetically altered with the gfp gene produce a protein that fluoresces when it is excited by uv light. this unique phenotype allows gfp-tagged cells to be specifically monitored by nondestructive means. in this study we determined whether a gfp-tagged strain of pseudomonas fluorescen ... | 2000 | 10919764 |
| a genomic sample sequence of the entomopathogenic bacterium photorhabdus luminescens w14: potential implications for virulence. | photorhabdus luminescens is a pathogenic bacterium that lives in the guts of insect-pathogenic nematodes. after invasion of an insect host by a nematode, bacteria are released from the nematode gut and help kill the insect, in which both the bacteria and the nematodes subsequently replicate. however, the bacterial virulence factors associated with this "symbiosis of pathogens" remain largely obscure. in order to identify genes encoding potential virulence factors, we performed approximately 2,00 ... | 2000 | 10919786 |
| rapid methods for testing the efficacy of sterilization-grade filter membranes. | the validation of sterilization-grade membranes is integral to ensuring the efficient and safe use of microfiltration systems. here validation refers to the production of sterile filtrate for sterilizing-grade membranes under challenge test conditions. current validation methods require 48 h of culture for results to become available, which creates time delays within the manufacturing process and quality control (qc) backlogs. this work compares four methods for the production of filter challeng ... | 2000 | 10919803 |
| expression of a functional antizearalenone single-chain fv antibody in transgenic arabidopsis plants. | the efficacy of cloning a recombinant mycotoxin antibody in plants was tested using arabidopsis as a model. an antizearalenone single-chain fv (scfv) dna fragment was first cloned in the newly constructed phage display vector (pey.5) and then recloned in the plant transformation vector pkylx71::35s(2). after transformation, constructs of antizearalenone scfv were introduced into immature arabidopsis seeds via agrobacterium tumefaciens mediation by vacuum infiltration. only plants transformed wit ... | 2000 | 10919813 |
| direct interaction of resistance gene and avirulence gene products confers rice blast resistance. | rice expressing the pi-ta gene is resistant to strains of the rice blast fungus, magnaporthe grisea, expressing avr-pita in a gene-for-gene relationship. pi-ta encodes a putative cytoplasmic receptor with a centrally localized nucleotide-binding site and leucine-rich domain (lrd) at the c-terminus. avr-pita is predicted to encode a metalloprotease with an n-terminal secretory signal and pro-protein sequences. avr-pita(176) lacks the secretory and pro-protein sequences. we report here that transi ... | 2000 | 10921881 |
| pseudomonas syringae hrp type iii secretion system and effector proteins. | pseudomonas syringae is a member of an important group of gram-negative bacterial pathogens of plants and animals that depend on a type iii secretion system to inject virulence effector proteins into host cells. in p. syringae, hrp/hrc genes encode the hrp (type iii secretion) system, and avirulence (avr) and hrp-dependent outer protein (hop) genes encode effector proteins. the hrp/hrc genes of p. syringae pv syringae 61, p. syringae pv syringae b728a, and p. syringae pv tomato dc3000 are flanke ... | 2000 | 10922033 |
| molecular and cell biology aspects of plague. | a 70-kb virulence plasmid (sometimes called pyv) enables yersinia spp. to survive and multiply in the lymphoid tissues of their host. it encodes the yop virulon, a system consisting of secreted proteins called yops and their dedicated type iii secretion apparatus called ysc. the ysc apparatus forms a channel composed of 29 proteins. of these, 10 have counterparts in almost every type iii system. secretion of some yops requires the assistance, in the bacterial cytosol, of small individual chapero ... | 2000 | 10922034 |
| plants and animals share functionally common bacterial virulence factors. | by exploiting the ability of pseudomonas aeruginosa to infect a variety of vertebrate and nonvertebrate hosts, we have developed model systems that use plants and nematodes as adjuncts to mammalian models to help elucidate the molecular basis of p. aeruginosa pathogenesis. our studies reveal a remarkable degree of conservation in the virulence mechanisms used by p. aeruginosa to infect hosts of divergent evolutionary origins. | 2000 | 10922040 |
| avrpto-dependent pto-interacting proteins and avrpto-interacting proteins in tomato. | the plant-intracellular interaction of the avirulence protein avrpto of pseudomonas syringae pathovar tomato, the agent of bacterial speck disease, and the corresponding tomato resistance protein pto triggers responses leading to disease resistance. pto, a serine/threonine protein kinase, also interacts with a putative downstream kinase, pto-interactor 1, as well as with members of a family of transcription factors pto-interactors 4, 5, and 6. these proteins are likely involved, respectively, in ... | 2000 | 10922043 |
| nitric oxide and salicylic acid signaling in plant defense. | salicylic acid (sa) plays a critical signaling role in the activation of plant defense responses after pathogen attack. we have identified several potential components of the sa signaling pathway, including (i) the h(2)o(2)-scavenging enzymes catalase and ascorbate peroxidase, (ii) a high affinity sa-binding protein (sabp2), (iii) a sa-inducible protein kinase (sipk), (iv) npr1, an ankyrin repeat-containing protein that exhibits limited homology to ikappabalpha and is required for sa signaling, ... | 2000 | 10922045 |
| requirement of sphingolipid alpha-hydroxylation for fungicidal action of syringomycin e. | syringomycin e is an antifungal cyclic lipodepsinonapeptide produced by pseudomonas syringae pv. syringae. to understand the mechanism of action of syringomycin e, a novel resistant saccharomyces cerevisiae strain, bw7, was isolated and characterized. lipid analyses revealed that bw7 contained only the hydrophobic subspecies of sphingolipids that are normally minor components in wild type strains. this aberrant sphingolipid composition was the result of lack of alpha-hydroxylation of the amide-l ... | 2000 | 10922463 |
| conversion of compatible plant-pathogen interactions into incompatible interactions by expression of the pseudomonas syringae pv. syringae 61 hrma gene in transgenic tobacco plants. | the hrma gene from pseudomonas syringae pv. syringae has previously been shown to confer avirulence on the virulent bacterium p. syringae pv. tabaci in all examined tobacco cultivars. we expressed this gene in tobacco plants under the control of the tobacco delta0. 3 tobrb7 promoter, which is induced upon nematode infection in tobacco roots (opperman et al. 1994, science, 263, 221-223). a basal level of hrma expression in leaves of transgenic plants activated the expression of pathogenesis-relat ... | 2000 | 10929114 |
| the virulence factor avrxa7 of xanthomonas oryzae pv. oryzae is a type iii secretion pathway-dependent nuclear-localized double-stranded dna-binding protein. | avrxa7 is a member of the avrbs3 avirulence gene family, which encodes proteins targeted to plant cells by a type iii secretion apparatus. avrxa7, the product of avrxa7, is also a virulence factor in strain pxo86 of xanthomonas oryzae pv. oryzae. avirulence and virulence specificities are associated with the central repeat domain, which, in avrxa7, consists of 25.5 direct repeat units. mutations in three c-terminal nuclear localization signal motifs eliminated avirulence and virulence activities ... | 2000 | 10931960 |
| expression of single chain antibodies (scfvs) for c-myc oncoprotein in recombinant escherichia coli membranes by using the ice-nucleation protein of pseudomonas syringae. | the ice nucleation protein (inp) is a glycosyl phosphatidylinositol anchored outer membrane protein found in certain gram-negative bacteria. in this study, the inp from pseudomonas syringae was applied as a fusion partner with the single chain antibody fragment (scfv) against the human oncoprotein c-myc. two new plasmids pninaz-myc and pninazscfv-bsaa1 were constructed and cloned into escherichia coli jm109. the expression of the fusion protein was successfully demonstrated in the cloned cells. ... | 2000 | 10933828 |
| induced expression of sarcotoxin ia enhanced host resistance against both bacterial and fungal pathogens in transgenic tobacco. | we demonstrate here that induced expression of sarcotoxin ia, a bactericidal peptide from sarcophaga peregrina, enhanced the resistance of transgenic tobacco plants to both bacterial and fungal pathogens. the peptide was produced with a modified pr1a promoter, which is further activated by salicylic acid treatment and necrotic lesion formation by pathogen infection. host resistance to infection of bacteria erwinia carotovora subsp. carotovora and pseudomonas syringae pv. tabaci was shown to be d ... | 2000 | 10939257 |
| evidence for a role of the n terminus and leucine-rich repeat region of the mi gene product in regulation of localized cell death. | the tomato mi gene confers resistance against root-knot nematodes and potato aphids. chimeric constructs of the functional gene, mi-1. 2, with a homolog, mi-1.1, were produced, and their phenotypes were examined in agrobacterium rhizogenes-transformed roots. exchange of the leucine-rich repeat (lrr) region of mi-1.1 into mi-1.2 resulted in the loss of ability to confer nematode resistance, as did substitution of a 6-amino acid sequence from the mi-1.1 lrr into mi-1.2. introduction of the mi-1.2 ... | 2000 | 10948252 |
| receptor-mediated increase in cytoplasmic free calcium required for activation of pathogen defense in parsley. | transient influx of ca(2+) constitutes an early element of signaling cascades triggering pathogen defense responses in plant cells. treatment with the phytophthora sojae-derived oligopeptide elicitor, pep-13, of parsley cells stably expressing apoaequorin revealed a rapid increase in cytoplasmic free calcium ([ca(2+)](cyt)), which peaked at approximately 1 microm and subsequently declined to sustained values of 300 nm. activation of this biphasic [ca(2+)](cyt) signature was achieved by elicitor ... | 2000 | 10948260 |
| constitutive expression of the defense-related rir1b gene in transgenic rice plants confers enhanced resistance to the rice blast fungus magnaporthe grisea. | the rirlb gene of rice (oryza sativa) is one of a set of putative defense genes whose transcripts accumulate upon inoculation of rice with the non-host pathogen pseudomonas syringae pv. syringae. it belongs to a family of genes encoding small extracellular proteins so far only identified in cereals. to assess the function of the rirlb gene in rice blast resistance, it was placed under the control of the camv 35s promoter and transferred into rice plants of the japonica variety taipei 309 by biol ... | 2000 | 10949374 |
| chemoenzymatic synthesis of the microbial elicitor (-)-syringolide via a fructose 1,6-diphosphate aldolase-catalyzed condensation reaction. | syringolide 2, an elicitor of the bacterial plant pathogen pseudomonas syringae pv. tomato which triggers a hypersensitive defense response in resistant soybean plants, has been synthesized in five steps via a fructose 1,6-diphosphate aldolase reaction. | 2000 | 10959854 |
| plasmid-located pathogenicity determinants of serratia entomophila, the causal agent of amber disease of grass grub, show similarity to the insecticidal toxins of photorhabdus luminescens. | serratia entomophila and serratia proteamaculans cause amber disease in the grass grub costelytra zealandica (coleoptera: scarabaeidae), an important pasture pest in new zealand. larval disease symptoms include cessation of feeding, clearance of the gut, amber coloration, and eventual death. a 115-kb plasmid, padap, identified in s. entomophila is required for disease causation and, when introduced into escherichia coli, enables that organism to cause amber disease. a 23-kb fragment of padap tha ... | 2000 | 10960097 |
| cloning and characterization of the glucooligosaccharide catabolic pathway beta-glucan glucohydrolase and cellobiose phosphorylase in the marine hyperthermophile thermotoga neapolitana. | characterization in thermotoga neapolitana of a catabolic gene cluster encoding two glycosyl hydrolases, 1,4-beta-d-glucan glucohydrolase (ggha) and cellobiose phosphorylase (cbpa), and the apparent absence of a cellobiohydrolase (cbh) suggest a nonconventional pathway for glucan utilization in thermotogales. ggha purified from t. neapolitana is a 52.5-kda family 1 glycosyl hydrolase with optimal activity at ph 6.5 and 95 degrees c. ggha releases glucose from soluble glucooligomers, with a prefe ... | 2000 | 10960102 |
| mutations in multidrug efflux homologs, sugar isomerases, and antimicrobial biosynthesis genes differentially elevate activity of the sigma(x) and sigma(w) factors in bacillus subtilis. | the sigma(x) and sigma(w) extracytoplasmic function sigma factors regulate more than 40 genes in bacillus subtilis. sigma(w) activates genes which function in detoxification and the production of antimicrobial compounds, while sigma(x) activates functions that modify the cell envelope. transposon mutagenesis was used to identify loci which negatively regulate sigma(w) or sigma(x) as judged by up-regulation from the autoregulatory promoter site p(w) or p(x). fourteen insertions that activate p(w) ... | 2000 | 10960106 |
| the octadecanoid pathway is required for pathogen-induced multi-functional acetyl-coa carboxylase accumulation in common bean (phaseolus vulgaris l.). | a partial cdna clone corresponding to the multi-functional acetyl-coa carboxylase (accase, ec 6.4.1.2) was isolated using rna extracted from methyl jasmonate (meja)-induced common bean cell cultures. most of this clone corresponds to the 3' untranslated region and it showed high identity to alfalfa and soybean accase sequences. southern hybridization revealed one copy of this gene in the common bean genome. in addition to being induced by meja in cell cultures and leaves, accase mrna accumulated ... | 2000 | 10960731 |
| genotypic characterization of bradyrhizobium strains nodulating small senegalese legumes by 16s-23s rrna intergenic gene spacers and amplified fragment length polymorphism fingerprint analyses. | we examined the genotypic diversity of 64 bradyrhizobium strains isolated from nodules from 27 native leguminous plant species in senegal (west africa) belonging to the genera abrus, alysicarpus, bryaspis, chamaecrista, cassia, crotalaria, desmodium, eriosema, indigofera, moghania, rhynchosia, sesbania, tephrosia, and zornia, which play an ecological role and have agronomic potential in arid regions. the strains were characterized by intergenic spacer (between 16s and 23s rrna genes) pcr and res ... | 2000 | 10966419 |
| purification and characterization of novel antifungal compounds from the sourdough lactobacillus plantarum strain 21b. | sourdough lactic acid bacteria were selected for antifungal activity by a conidial germination assay. the 10-fold-concentrated culture filtrate of lactobacillus plantarum 21b grown in wheat flour hydrolysate almost completely inhibited eurotium repens ibt18000, eurotium rubrum ftdc3228, penicillium corylophilum ibt6978, penicillium roqueforti ibt18687, penicillium expansum idm/fs2, endomyces fibuliger ibt605 and idm3812, aspergillus niger ftdc3227 and idm1, aspergillus flavus ftdc3226, monilia s ... | 2000 | 10966432 |
| ice crystallization by pseudomonas syringae. | several bacterial species can serve as biological ice nuclei. the best characterized of these is pseudomonas syringae, a widely distributed bacterial epiphyte of plants. these biological ice nuclei find various applications in different fields, but an optimized production method was required in order to obtain the highly active cells which may be exploited as ice nucleators. the results presented here show that p. syringae cells reduce supercooling of liquid or solid media and enhance ice crysta ... | 2000 | 10968626 |
| novel fosfomycin resistance of pseudomonas aeruginosa clinical isolates recovered in japan in 1996. | 2000 | 10970248 | |
| the rpm1 plant disease resistance gene facilitates a rapid and sustained increase in cytosolic calcium that is necessary for the oxidative burst and hypersensitive cell death. | early events occurring during the hypersensitive resistance response (hr) were examined using the avrrpm1/rpm1 gene-for-gene interaction in arabidopsis challenged by pseudomonas syringae pv. tomato. increases in cytosolic ca2+ were measured in whole leaves using aequorin-mediated bioluminescence. during the hr a sustained increase in ca2+ was observed which was dependent on the presence of both a functional rpm1 gene product and delivery of the cognate avirulence gene product avrrpm1. the sequen ... | 2000 | 10972870 |
| a loss of resistance to avirulent bacterial pathogens in tobacco is associated with the attenuation of a salicylic acid-potentiated oxidative burst. | the role of salicylic acid (sa) in events occurring before cell death during the hypersensitive reaction (hr) was investigated in leaves of wild-type tobacco samsun nn and in transgenic lines expressing salicylate hydroxylase (35s-sh-l). challenge of 35s-sh-l tobacco with avirulent strains of pseudomonas syringae gave rise to symptoms resembling those normally associated with a compatible response to virulent strains in terms of visible phenotype, kinetics of bacterial multiplication, and escape ... | 2000 | 10972887 |
| bacteria in the leaf ecosystem with emphasis on pseudomonas syringae-a pathogen, ice nucleus, and epiphyte. | the extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. this review focuses on the bacterial component of leaf microbial communities, with emphasis on pseudomonas syringae-a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. among the diversity of bacteria that colonize leaves, none has received wider attention than p. syringae, as it gained notoriety for being the firs ... | 2000 | 10974129 |
| interactions of pseudomonas syringae pv. glycinea with host and nonhost plants in relation to temperature and phytotoxin synthesis. | pseudomonas syringae pv. glycinea pg4180 causes bacterial blight of soybean and produces the phytotoxin coronatine (cor) in a temperature-dependent manner. cor consists of a polyketide, coronafacic acid (cfa), and an amino acid derivative, coronamic acid, and is produced optimally at 18 degrees c whereas no detectable synthesis occurs at 28 degrees c. we investigated the impact of temperature on pg4180 during compatible and incompatible interactions with soybean and tobacco plants, respectively. ... | 2000 | 10975652 |
| uncoupling salicylic acid-dependent cell death and defense-related responses from disease resistance in the arabidopsis mutant acd5. | salicylic acid (sa) is required for resistance to many diseases in higher plants. sa-dependent cell death and defense-related responses have been correlated with disease resistance. the accelerated cell death 5 mutant of arabidopsis provides additional genetic evidence that sa regulates cell death and defense-related responses. however, in acd5, these events are uncoupled from disease resistance. acd5 plants are more susceptible to pseudomonas syringae early in development and show spontaneous s ... | 2000 | 10978297 |
| variation and phylogenetic utility of the arabidopsis thaliana rps2 homolog in various species of the tribe brassiceae. | our objective was to analyze the evolutionary paths of cultivated diploid brassica species and a few related wild species (tribe brassiceae) in relation to arabidopsis thaliana (tribe arabidae), using the rps2 sequence. rps2 confers resistance to pseudomonas syringae in a. thaliana. we found that similar to arabidopsis, the rps2 homolog in brassica species is present in a single copy. primers based in the rps2 sequence amplified rps2 homologs from the other species. maximum-parsimony analysis ba ... | 2000 | 10991796 |
| in vitro antimicrobial properties of recombinant asabf, an antimicrobial peptide isolated from the nematode ascaris suum. | asabf is a csalphabeta-type antimicrobial peptide that contains four intramolecular disulfide bridges (y. kato and s. komatsu, j. biol. chem. 271:30493-30498, 1996). in the present study, a recombinant asabf was produced by using a yeast expression system, and its antimicrobial activity was characterized in detail. the recombinant asabf was active against all gram-positive bacteria tested (7 of 7; minimum bactericidal concentration [mbc], 0.03 to 1 microg/ml) except leuconostoc mesenteroides, so ... | 2000 | 10991847 |
| characterization of rci-1, a chloroplastic rice lipoxygenase whose synthesis is induced by chemical plant resistance activators. | a full-length lipoxygenase cdna (rci-1) has been cloned from rice (oryza sativa) whose corresponding transcripts accumulate in response to treatment of the plants with chemical inducers of acquired resistance such as benzo(1,2,3)thiadiazole-7-carbothioic acid s-methyl ester (bth), 2,6-dichloroisonicotinic acid (ina), and probenazole. in contrast, rci-1 transcript levels did not increase after inoculation with compatible and incompatible races of the rice blast fungus magnaporthe grisea and the n ... | 2000 | 10998053 |
| leafy gall formation is controlled by fasr, an arac-type regulatory gene in rhodococcus fascians. | rhodococcus fascians can interact with many plant species and induce the formation of either leafy galls or fasciations. to provoke symptoms, r. fascians strain d188 requires pathogenicity genes that are located on a linear plasmid, pfid188. the fas genes are essential for virulence and constitute an operon that encodes, among other functions, a cytokinin synthase gene. expression of the fas genes is induced by extracts of infected plant tissue only. we have isolated an arac-type regulatory gene ... | 2000 | 11004184 |
| identification of a copper-responsive two-component system on the chromosome of escherichia coli k-12. | using a genetic screen we have identified two chromosomal genes, cusrs (ylca ybcz), from escherichia coli k-12 that encode a two-component, signal transduction system that is responsive to copper ions. this regulatory system is required for copper-induced expression of pcoe, a plasmid-borne gene from the e. coli copper resistance operon pco. the closest homologs of cusr and cuss are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: pcor and pcos from ... | 2000 | 11004187 |
| genetic manipulation of isoflavone 7-o-methyltransferase enhances biosynthesis of 4'-o-methylated isoflavonoid phytoalexins and disease resistance in alfalfa. | 4'-o-methylation of an isoflavonoid intermediate is a key reaction in the biosynthesis of the phytoalexin medicarpin in legumes. however, isoflavone o-methyltransferase (iomt) from alfalfa converts the isoflavone daidzein to 7-o-methyl daidzein (isoformononetin) in vitro as well as in vivo in unchallenged leaves of transgenic alfalfa ectopically expressing iomt. in contrast, elicitation of iomt-overexpressing plants with cucl(2) or infecting these plants with phoma medicaginis leads to greater a ... | 2000 | 11006341 |
| development of genetic tools for lactobacillus sakei: disruption of the beta-galactosidase gene and use of lacz as a reporter gene to study regulation of the putative copper atpase, atkb. | downstream from the ptshi operon of lactobacillus sakei, the genes atky and atkb, organized in an operon, were observed. the two putative proteins, atkb and atky, show sequence similarity to the enterococcus hirae copper p-type atpase, responsible for copper efflux, and its negative regulator. characterization of atkb as a copper p-type atpase could not be demonstrated since an atkb mutant did not show any phenotype. thus, another strategy was followed in order to investigate the transcriptional ... | 2000 | 11010870 |
| vesicle-mediated transfer of virulence genes from escherichia coli o157:h7 to other enteric bacteria. | membrane vesicles are released from the surfaces of many gram-negative bacteria during growth. vesicles consist of proteins, lipopolysaccharide, phospholipids, rna, and dna. results of the present study demonstrate that membrane vesicles isolated from the food-borne pathogen escherichia coli o157:h7 facilitate the transfer of genes, which are then expressed by recipient salmonella enterica serovar enteritidis or e. coli jm109. electron micrographs of purified dna from e. coli o157:h7 vesicles sh ... | 2000 | 11010892 |
| pcr assays that identify the grapevine dieback fungus eutypa lata. | eutypa lata is the causal fungal agent of eutypa dieback, a serious grapevine necrotic disease. the erratic and delayed (1 to 2 months) appearance of characteristic conidia on culture media and the presence of numerous microorganisms in decaying wood make it difficult either to identify or to detect e. lata in grapevine wood samples. we designed six pairs of pcr primers for diagnosis of e. lata. three primer pairs were derived from ribosomal dna internal transcribed spacer sequences, and three p ... | 2000 | 11010901 |
| colonization strategies and conjugal gene transfer of inoculated pseudomonas syringae on the leaf surface. | survival, colonization and activity of pseudomonas syringae bacteria inoculated onto the leaf surface of the common bean (phaseolus vulgaris) was studied. inoculated ps. syringae cells shortened by half their size in 100% humidity and by an average of one fifth in 40-60% humidity. the respiring portion of the population, measured by the formation of 5-cyano-2,3-ditolyl tetrazolium chloride (ctc)-formazan crystals, decreased more in 40-60% humidity than in 100% humidity. in scanning electron micr ... | 2000 | 11021574 |
| phylogeny of the replication regions of ppt23a-like plasmids from pseudomonas syringae. | it was previously shown that most pseudomonas syringae strains contain one or more plasmids with cross-hybridizing replication regions and other areas of homology, and these plasmids were designated the ppt23a-like family. the majority of these plasmids encode genes conferring epiphytic fitness or resistance to antibacterial compounds and those investigated in this study are essential for pathogenicity or increased virulence. the phylogeny of 14 ppt23a-like plasmids from five p. syringae pathova ... | 2000 | 11021914 |
| heterogeneity of iron bioavailability on plants assessed with a whole-cell gfp-based bacterial biosensor. | ferric iron is an essential element for microbial growth but its water solubility in aerobic environments is considered to be low. thus it is a limiting resource for which microbes must compete in natural habitats. since competition for iron occurs at the level of individual cells, knowledge of the variability in iron bioavailability to such individuals is required to assess the nature of the competition in these habitats. ferric iron availability to cells of pseudomonas syringae was assessed by ... | 2000 | 11021920 |
| regulatory interactions between the hrp type iii protein secretion system and coronatine biosynthesis in pseudomonas syringae pv. tomato dc3000. | in p. syringae, the co-ordinated regulation of different systems required for pathogenicity and virulence seems logical but has not been established. this question was addressed in the present study by analysing production of the phytotoxin coronatine (cor) in defined hrp/hrc mutants of p. syringae pv. tomato dc3000. cor was produced in vitro by mutants of dc3000 defective in hrcc, which encodes an outer-membrane protein required for type iii-mediated secretion. when inoculated in plants, hrcc m ... | 2000 | 11021921 |
| temperature-responsive genetic loci in the plant pathogen pseudomonas syringae pv. glycinea. | plant-pathogenic bacteria may sense variations in environmental factors, such as temperature, to adapt to plant-associated habitats during pathogenesis or epiphytic growth. the bacterial blight pathogen of soybean, pseudomonas syringae pv. glycinea pg4180, preferentially produces the phytotoxin coronatine at 18 degrees c and infects the host plant under conditions of low temperature and high humidity. a minitn5-based promoterless glucuronidase (uida) reporter gene was used to identify genetic lo ... | 2000 | 11021922 |
| identification of genes associated with copper tolerance in an adhesion-defective mutant of aeromonas veronii biovar sobria. | tnphoa mutagenesis was used to identify adhesins of aeromonas veronii biovar sobria 3767, a strain isolated from a diarrhoeal stool specimen. six mutants, from a library of 154, exhibited significantly reduced levels of adhesion to hep-2 cells. primers to the terminal regions of tnphoa were used for inverse pcr and the product from one mutant was cloned into pbluescript and partial sequence data obtained. scanning genbank and embl data bases revealed dna sequence similarity to the copa gene of p ... | 2000 | 11024350 |