| isolation of an insertion sequence from ralstonia solanacearum race 1 and its potential use for strain characterization and detection. | a new insertion sequence (is), is1405, was isolated and characterized from a ralstonia solanacearum race 1 strain by the method of insertional inactivation of the sacb gene. sequence analysis indicated that the is is closely related to the members of is5 family, but the extent of nucleotide sequence identity in 5' and 3' noncoding regions between is1405 and other members of is5 family is only 23 to 31%. nucleotide sequences of these regions were used to design specific oligonucleotide primers fo ... | 2001 | 11525989 |
| effect of model sorptive phases on phenanthrene biodegradation: molecular analysis of enrichments and isolates suggests selection based on bioavailability. | reduced bioavailability of nonpolar contaminants due to sorption to natural organic matter is an important factor controlling biodegradation of pollutants in the environment. we established enrichment cultures in which solid organic phases were used to reduce phenanthrene bioavailability to different degrees (r. j. grosser, m. friedrich, d. m. ward, and w. p. inskeep, appl. environ. microbiol. 66:2695-2702, 2000). bacteria enriched and isolated from contaminated soils under these conditions were ... | 2000 | 10877758 |
| detection of ralstonia solanacearum strains with a quantitative, multiplex, real-time, fluorogenic pcr (taqman) assay. | a fluorogenic (taqman) pcr assay was developed to detect ralstonia solanacearum strains. two fluorogenic probes were utilized in a multiplex reaction; one broad-range probe (rs) detected all biovars of r. solanacearum, and a second more specific probe (b2) detected only biovar 2a. amplification of the target was measured by the 5' nuclease activity of taq dna polymerase on each probe, resulting in emission of fluorescence. taqman pcr was performed with dna extracted from 42 r. solanacearum and g ... | 2000 | 10877778 |
| a framework for interpreting the leucine-rich repeats of the listeria internalins. | the surface protein inlb of the bacterial pathogen listeria monocytogenes is required for inducing phagocytosis in various nonphagocytic mammalian cell types in vitro. inlb causes tyrosine phosphorylation of host cell adaptor proteins, activation of phosphoinositide 3-kinase, and rearrangements of the actin cytoskeleton. these events lead to phagocytic uptake of the bacterium by the host cell. inlb belongs to the internalin family of listeria proteins, which also includes inla, another surface p ... | 2000 | 10922035 |
| identification and detection of stenotrophomonas maltophilia by rrna-directed pcr. | stenotrophomonas maltophilia has recently emerged as an important nosocomial pathogen in immunocompromised patients, in transplant recipients, and in persons with cystic fibrosis (cf). while this organism is nonpathogenic in healthy individuals, it is increasingly associated with morbidity and mortality in susceptible populations. recent studies have indicated that for approximately 10% of cf patients with moderate lung disease, s. maltophilia can be cultured from respiratory tract secretions. i ... | 2000 | 11101555 |
| complete nucleotide sequence and organization of the atrazine catabolic plasmid padp-1 from pseudomonas sp. strain adp. | the complete 108,845-nucleotide sequence of catabolic plasmid padp-1 from pseudomonas sp. strain adp was determined. plasmid padp-1 was previously shown to encode atza, atzb, and atzc, which catalyze the sequential hydrolytic removal of s-triazine ring substituents from the herbicide atrazine to yield cyanuric acid. computational analyses indicated that padp-1 encodes 104 putative open reading frames (orfs), which are predicted to function in catabolism, transposition, and plasmid maintenance, t ... | 2001 | 11544232 |
| a putative type iii secretion gene cluster is widely distributed in the burkholderia cepacia complex but absent from genomovar i. | using probes constructed from ralstonia solanacearum and burkholderia pseudomallei, putative type iii secretion (tts) genes were identified in burkholderia cepacia j2315 (genomovar iii). a cosmid clone containing dna with homology to five tts genes was sub-cloned and regions were sequenced in order to design oligonucleotides for polymerase chain reaction assays. these indicated that two putative tts genes (bcscq and bcscv) were present in all members of the b. cepacia complex with the exception ... | 2001 | 11557147 |
| resistance of tomato line hawaii7996 to ralstonia solanacearum pss4 in taiwan is controlled mainly by a major strain-specific locus. | bacterial wilt caused by the soilborne bacterium ralstonia solanacearum attacks hundreds of plant species, including many agriculturally important crops. natural resistance to this disease has been found in some species and is usually inherited as a polygenic trait. in tomato, a model crop plant, genetic analysis previously revealed the involvement of several qtl (quantitative trait loci) controlling resistance and, in all of these studies with different strains of the pathogen, loci on chromoso ... | 2000 | 10656580 |
| taxonomy and identification of the burkholderia cepacia complex. | | 2001 | 11574551 |
| two-component system that regulates methanol and formaldehyde oxidation in paracoccus denitrificans. | a chromosomal region encoding a two-component regulatory system, flhrs, has been isolated from paracoccus denitrificans. flhrs-deficient mutants were unable to grow on methanol, methylamine, or choline as the carbon and energy source. expression of the gene encoding glutathione-dependent formaldehyde dehydrogenase (fhla) was undetectable in the mutant, and expression of the s-formylglutathione hydrolase gene (fgha) was reduced in the mutant background. in addition, methanol dehydrogenase was imm ... | 2001 | 11133961 |
| identification of a group 1-like capsular polysaccharide operon for vibrio vulnificus. | virulence of vibrio vulnificus correlates with changes in colony morphology that are indicative of a reversible phase variation for expression of capsular polysaccharide (cps). encapsulated variants are virulent with opaque colonies, whereas phase variants with reduced cps expression are attenuated and are translucent. using tnphoa mutagenesis, we identified a v. vulnificus cps locus, which included an upstream ops element, a wza gene (wza(vv)), and several open reading frames with homology to c ... | 2001 | 11598064 |
| detection and quantification of methyl tert-butyl ether-degrading strain pm1 by real-time taqman pcr. | the fuel oxygenate methyl tert-butyl ether (mtbe), a widely distributed groundwater contaminant, shows potential for treatment by in situ bioremediation. the bacterial strain pm1 rapidly mineralizes and grows on mtbe in laboratory cultures and can degrade the contaminant when inoculated into groundwater or soil microcosms. we applied the taqman quantitative pcr method to detect and quantify strain pm1 in laboratory and field samples. specific primers and probes were designed for the 16s ribosoma ... | 2001 | 11679339 |
| hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. | the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ... | 2001 | 11134504 |
| hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. | the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ... | 2001 | 11134504 |
| source of resistance against ralstonia solanacearum in fertile somatic hybrids of eggplant (solanum melongena l.) with solanum aethiopicum l. | solanum aethiopicum is reported to carry resistance to bacterial wilt disease caused by ralstonia solanacearum, which is one of the most important diseases of eggplant (solanum melongena). these two species can sexually be crossed but the fertility of their progeny is very low. in order to transfer the resistance and improve the fertility, somatic hybrids between s. melongena cv. dourga and two groups of s. aethiopicum were produced by electrical fusion of mesophyll protoplasts. thirty hybrid pl ... | 2001 | 11164602 |
| the insect endosymbiont sodalis glossinidius utilizes a type iii secretion system for cell invasion. | sodalis glossinidius is a maternally transmitted secondary endosymbiont residing intracellularly in tissues of the tsetse flies, glossina spp. in this study, we have used tn5 mutagenesis and a negative selection procedure to derive a s. glossinidius mutant that is incapable of invading insect cells in vitro and is aposymbiotic when microinjected into tsetse. this mutant strain harbors tn5 integrated into a chromosomal gene sharing high sequence identity with a type iii secretion system invasion ... | 2001 | 11172045 |
| intra- and interspecies regulation of gene expression by actinobacillus actinomycetemcomitans luxs. | the cell density-dependent control of gene expression is employed by many bacteria for regulating a variety of physiological functions, including the generation of bioluminescence, sporulation, formation of biofilms, and the expression of virulence factors. although periodontal organisms do not appear to secrete acyl-homoserine lactone signals, several species, e.g., porphyromonas gingivalis, prevotella intermedia, and fusobacterium nucleatum, have recently been shown to secrete a signal related ... | 2001 | 11705942 |
| genetic evidence that loss of virulence associated with gacs or gaca mutations in pseudomonas syringae b728a does not result from effects on alginate production. | mutations in the global regulatory genes gacs and gaca render pseudomonas syringae pv. syringae strain b728a completely nonpathogenic in foliar infiltration assays on bean plants. it had been previously demonstrated that gac genes regulate alginate production in pseudomonas species, while other published work indicated that alginate is involved in the pathogenic interaction of p. syringae on bean plants. together, these results suggested that the effects of gacs and gaca mutations on virulence i ... | 2001 | 11229941 |
| partial sequencing of the hrpb and endoglucanase genes confirms and expands the known diversity within the ralstonia solanacearum species complex. | we determined partial hrpb and endoglucanase genes sequences for 30 strains of ralstonia solanacearum and one strain of the blood disease bacterium (bdb), a close relative of ralstonia solanacearum. sequence comparisons showed high levels of variability within these two regions of the genome involved in pathogenicity. phylogenetic analysis based upon sequence comparisons of these two regions revealed three major clusters comprising all ralstonia solanacearum isolates, the bdb strain constituted ... | 2000 | 11249017 |
| spa33, a cell surface-associated subunit of the mxi-spa type iii secretory pathway of shigella flexneri, regulates ipa protein traffic. | the mxi-spa type iii secretion system of shigella flexneri directs the host cell contact-induced secretion of a set of invasins, referred to as ipas. in this study, we examined the role of spa33 in ipa secretion. a spa33-null mutant was both noninvasive and unable to translocate the ipas from inner membrane to outer membrane (om) positions of the mxi-spa transmembrane channel. spa33 was found to be a mxi-spa substrate that is translocated to the bacterial cell surface upon the induction of ipa s ... | 2001 | 11254573 |
| classification of ralstonia pickettii biovar 3/'thomasii' strains (pickett 1994) and of new isolates related to nosocomial recurrent meningitis as ralstonia mannitolytica sp. nov. | strains isolated independently from two patients could be recognized as ralstonia pickettii biovar 3/'thomasii'. the 16s rdna sequences of these strains and two other strains of r. pickettii biovar 3/'thomasii' clustered at less than 98% similarity versus all other described ralstonia species and at less than 97 % versus the two other r. pickettii biovars. the separate species status of r. pickettii biovar 3/'thomasii' was confirmed by dna-dna hybridization, indicating less than 60% dna homology ... | 2001 | 11321101 |
| characterization and mutational analysis of three allelic lsc genes encoding levansucrase in pseudomonas syringae. | in the plant pathogen pseudomonas syringae pv. glycinea pg4180 and other bacterial species, synthesis of the exopolysaccharide levan is catalyzed by the extracellular enzyme levansucrase. the results of southern blotting and pcr analysis indicated the presence of three levansucrase-encoding genes in strain pg4180: lsca, lscb, and lscc. in this study, lscb and lscc were cloned from a genomic library of strain pg4180. sequence analysis of the two lsc genes showed that they were virtually identical ... | 2001 | 11344135 |
| effects of synthetic cecropin analogs on in vitro growth of acholeplasma laidlawii. | four synthetic peptides (peptidyl mims; demeter biotechnologies, inc.) were evaluated for their in vitro activity against acholeplasma laidlawii. fifty percent effective concentration values ranged from 1 to 15 microm. three of these compounds are more lethal than cecropin b against a. laidlawii. | 2001 | 11353647 |
| generation of pcr-based dna fragments for specific detection of streptomyces saraceticus n45. | streptomyces saraceticus strain n45, a saprophytic gram-positive bacteria, has been shown to harbor high chitinase activity. due to its potential use in biological control, the cloning of chitinase genes and the development of methods to quickly and precisely detect its presence have become necessary. in this study, pcr-based random amplified polymorphic dna (rapd) and pcr strategies were used to amplify random dna fragments from the genome of s. saraceticus n45. three amplified dna fragments, 4 ... | 2001 | 11370759 |
| natural transformation of pseudomonas fluorescens and agrobacterium tumefaciens in soil. | little information is available concerning the occurrence of natural transformation of bacteria in soil, the frequency of such events, and the actual role of this process on bacterial evolution. this is because few bacteria are known to possess the genes required to develop competence and because the tested bacteria are unable to reach this physiological state in situ. in this study we found that two soil bacteria, agrobacterium tumefaciens and pseudomonas fluorescens, can undergo transformation ... | 2001 | 11375171 |
| in vivo detection of the cyclic osmoregulated periplasmic glucan of ralstonia solanacearum by high-resolution magic angle spinning nmr. | we investigate the mobility of the osmoregulated periplasmic glucans of ralstonia solanacearum in the bacterial periplasm through the use of high-resolution (hr) nmr spectroscopy under static and magic angle spinning (mas) conditions. because the nature of periplasm is far from an isotropic aqueous solution, the molecules could be freely diffusing or rather associated to a periplasmic protein, a membrane protein, a lipid, or the peptidoglycan. hr mas nmr spectroscopy leads to more reproducible r ... | 2001 | 11444945 |
| effect of genetically modified pseudomonas putida wcs358r on the fungal rhizosphere microflora of field-grown wheat. | we released genetically modified pseudomonas putida wcs358r into the rhizospheres of wheat plants. the two genetically modified derivatives, genetically modified microorganism (gmm) 2 and gmm 8, carried the phz biosynthetic gene locus of strain p. fluorescens 2-79 and constitutively produced the antifungal compound phenazine-1-carboxylic acid (pca). in the springs of 1997 and 1998 we sowed wheat seeds treated with either gmm 2, gmm 8, or wcs358r (approximately 10(7) cfu per seed), and measured t ... | 2001 | 11472906 |
| abscisic acid determines basal susceptibility of tomato to botrytis cinerea and suppresses salicylic acid-dependent signaling mechanisms. | abscisic acid (aba) is one of the plant hormones involved in the interaction between plants and pathogens. in this work, we show that tomato (lycopersicon esculentum mill. cv moneymaker) mutants with reduced aba levels (sitiens plants) are much more resistant to the necrotrophic fungus botrytis cinerea than wild-type (wt) plants. exogenous application of aba restored susceptibility to b. cinerea in sitiens plants and increased susceptibility in wt plants. these results indicate that aba plays a ... | 2002 | 11842153 |
| hsr203 antisense suppression in tobacco accelerates development of hypersensitive cell death. | activation of the tobacco gene hsr203 is rapid, highly localized, specific for incompatible plant-pathogen interactions, and strongly correlated with programmed cell death occurring in response to diverse pathogens. functional characterization of hsr203 gene product has shown that hsr203 is a serine hydrolase that displays esterase activity. we show here that transgenic tobacco plants deficient in hsr203 protein exhibit an accelerated hypersensitive response when inoculated with an avirulent str ... | 2001 | 11489189 |
| two novel type iii-secreted proteins of xanthomonas campestris pv. vesicatoria are encoded within the hrp pathogenicity island. | the hrp type iii protein secretion system (ttss) is essential for pathogenicity of gram-negative plant pathogen xanthomonas campestris pv. vesicatoria. cdna-amplified fragment length polymorphism and reverse transcription-pcr analyses identified new genes, regulated by key hrp regulator hrpg, in the regions flanking the hrp gene cluster. sequence analysis revealed genes encoding hpag, a predicted leucine-rich repeat-containing protein, the lysozyme-like hpah protein, and xopa and xopd, which are ... | 2002 | 11844763 |
| strain characterization and 16s-23s probe development for differentiating geographically dispersed isolates of the phytopathogen ralstonia solanacearum. | the causative agent of potato brown rot and bacterial wilt, ralstonia solanacearum, results in serious world-wide economic losses, particularly in the tropics. in the last decade, however, the incidence of bacterial wilt in potatoes grown in northern europe has increased, presenting an interesting epidemiological puzzle. its occurrence may be as a result of changes in agricultural practice or the emergence of a novel bacterial variety, better adapted to cooler conditions. to understand the distr ... | 2001 | 11846772 |
| quorum-sensing in gram-negative bacteria. | it has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. the languages by which bacteria communicate take the form of chemical signals, excreted from the cells, which can elicit profound physiological changes. many types of signalling molecules, which regulate diverse phenotypes across distant genera, h ... | 2001 | 11524130 |
| the viable but nonculturable state of ralstonia solanacearum may be involved in long-term survival and plant infection. | the role of the dormant-like viable but nonculturable (vbnc) condition in the etiology of bacterial infection was examined using a plant system. the plant-pathogenic bacterium ralstonia solanacearum was first shown to enter into the vbnc state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. to determine if the vbnc condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plant ... | 2001 | 11525979 |
| rapid identification and differentiation of the soft rot erwinias by 16s-23s intergenic transcribed spacer-pcr and restriction fragment length polymorphism analyses. | current identification methods for the soft rot erwinias are both imprecise and time-consuming. we have used the 16s-23s rrna intergenic transcribed spacer (its) to aid in their identification. analysis by its-pcr and its-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. the its was amplified from erwinia and other genera using universal pcr primers. after pcr, the banding patterns generated allow ... | 2001 | 11526007 |
| a second quorum-sensing system regulates cell surface properties but not phenazine antibiotic production in pseudomonas aureofaciens. | the root-associated biological control bacterium pseudomonas aureofaciens 30-84 produces a range of exoproducts, including protease and phenazines. phenazine antibiotic biosynthesis by phzxyfabcd is regulated in part by the phzr-phzi quorum-sensing system. mutants defective in phzr or phzi produce very low levels of phenazines but wild-type levels of exoprotease. in the present study, a second genomic region of strain 30-84 was identified that, when present in trans, increased beta-galactosidase ... | 2001 | 11526037 |
| identification of strains of alcaligenes and agrobacterium by a polyphasic approach. | the number of stable discriminant biochemical characters is limited in the genera alcaligenes and agrobacterium, whose species are consequently difficult to distinguish from one another by conventional tests. moreover, genomic studies have recently drastically modified the nomenclature of these genera; for example, alcaligenes xylosoxidans was transferred to the genus achromobacter in 1998. twenty-five strains of achromobacter xylosoxidans, three strains of an agrobacterium sp., five strains of ... | 2001 | 11526136 |
| spectral quality affects disease development of three pathogens on hydroponically grown plants. | plants were grown under light-emitting diode (led) arrays with various spectra to determine the effects of light quality on the development of diseases caused by tomato mosaic virus (tomv) on pepper (capsicum annuum l.), powdery mildew [sphaerotheca fuliginea (schlectend:fr.) pollaci] on cucumber (cucumis sativus l.), and bacterial wilt (pseudomonas solanacearum smith) on tomato (lycopersicon esculentum mill.). one led (660) array supplied 99% red light at 660 nm (25 nm bandwidth at half-peak he ... | 1997 | 11540250 |
| pathogenesis of the human opportunistic pathogen pseudomonas aeruginosa pa14 in arabidopsis. | the human opportunistic pathogen pseudomonas aeruginosa strain pa14 is a multihost pathogen that can infect arabidopsis. we found that pa14 pathogenesis in arabidopsis involves the following steps: attachment to the leaf surface, congregation of bacteria at and invasion through stomata or wounds, colonization of intercellular spaces, and concomitant disruption of plant cell wall and membrane structures, basipetal movement along the vascular parenchyma, and maceration and rotting of the petiole a ... | 2000 | 11115892 |
| functional analysis of hrpf, a putative type iii translocon protein from xanthomonas campestris pv. vesicatoria. | type iii secretion systems (ttsss) are specialized protein transport systems in gram-negative bacteria which target effector proteins into the host cell. the ttss of the plant pathogen xanthomonas campestris pv. vesicatoria, encoded by the hrp (hypersensitive reaction and pathogenicity) gene cluster, is essential for the interaction with the plant. one of the secreted proteins is hrpf, which is required for pathogenicity but dispensable for type iii secretion of effector proteins in vitro, sugge ... | 2002 | 11948151 |
| effects of ecological factors on the survival and physiology of ralstonia solanacearum bv. 2 in irrigation water. | the fate of ralstonia solanacearum bv. 2, the causative agent of brown rot in potato, in aquatic habitats of temperate climate regions is still poorly understood. in this study, the population dynamics and the physiological response of r. solanacearum bv. 2 were tested in sterile pure water and in agricultural drainage water obtained from waterways near potato cropping fields in the netherlands. the behaviour of five different biovar 2 isolates in drainage water at 20 degrees c was very similar ... | 2001 | 11683466 |
| the hrp pilus of pseudomonas syringae elongates from its tip and acts as a conduit for translocation of the effector protein hrpz. | the type iii secretion system (ttss) is an essential requirement for the virulence of many gram-negative bacteria infecting plants, animals and man. pathogens use the ttss to deliver effector proteins from the bacterial cytoplasm to the eukaryotic host cell, where the effectors subvert host defences. plant pathogens have to translocate their effector proteins through the plant cell wall barrier. the best candidates for directing effector protein traffic are bacterial appendages attached to the m ... | 2002 | 11953310 |
| chromosomal system for studying ampc-mediated beta-lactam resistance mutation in escherichia coli. | in some enterobacterial pathogens, but not in escherichia coli, loss-of-function mutations in the ampd gene are a common route to beta-lactam antibiotic resistance. we constructed an assay system for studying mechanism(s) of enterobacterial ampd mutation using the well-developed genetics of e. coli. we integrated the enterobacter amprc genes into the e. coli chromosome. these cells acquire spontaneous recombination- and sos response-independent beta-lactam resistance mutations in ampd. this chro ... | 2002 | 11959593 |
| control of virulence and pathogenicity genes of ralstonia solanacearum by an elaborate sensory network. | ralstonia solanacearum causes a lethal bacterial wilt disease of diverse plants. it invades the xylem vessels of roots and disseminates into the stem where it multiplies and wilts by excessive exopolysaccharide production. many of its key extracytoplasmic virulence and pathogenicity factors are transcriptionally controlled by an extensive network of distinct, interacting signal transduction pathways. the core of this sensory network is the five-gene phc system that regulates exopolysaccharide, c ... | 2000 | 11701844 |
| distribution of type iii secretion gene clusters in burkholderia pseudomallei, b. thailandensis and b. mallei. | burkholderia pseudomallei, the causative agent of melioidosis, carries a cluster of genes closely related in organisation to the type iii secretion (tts) system gene clusters of the plant pathogens ralstonia solanacearum and xanthomonas spp. the tts gene cluster (tts1) is present only in b. pseudomallei and not in avirulent b. thailandensis. adjacent to the gene cluster encoding putative secreton structural proteins lie a number of open reading frames (orfs) encoding putative proteins with littl ... | 2002 | 11990489 |
| identification of a quorum-sensing signal molecule in the facultative intracellular pathogen brucella melitensis. | brucella melitensis is a gram-negative alpha2-proteobacterium responsible for abortion in goats and for malta fever in humans. this facultative intracellular pathogen invades and survives within both professional and nonprofessional phagocytes. a dichloromethane extract of spent culture supernatant from b. melitensis induces bioluminescence in an escherichia coli acyl-homoserine lactone (acyl-hsl) biosensor strain based upon the activity of the lasr protein of pseudomonas aeruginosa. hplc fracti ... | 2002 | 12010991 |
| tropical plant pathology: at home and abroad. | i first describe my introduction to plant pathology and early experiences with employment, the environment, diseases, pests, and various plant pathologists. then i recount a decade of stimulating studies at the university of minnesota and the route i followed to a career in international agriculture with the rockefeller foundation in colombia and later at cornell university. my appreciation for and knowledge of traditional farmers and sustainable agriculture occurred as a slow awakening. comment ... | 2001 | 11701856 |
| osmoregulated periplasmic glucans of the free-living photosynthetic bacterium rhodobacter sphaeroides. | the osmoregulated periplasmic glucans (opgs) produced by rhodobacter sphaeroides, a free-living organism, were isolated by trichloracetic acid treatment and gel permeation chromatography. compounds obtained were characterized by compositional analysis, matrix-assisted laser desorption ionization mass spectrometry and nuclear magnetic resonance. r. sphaeroides predominantly synthesizes a cyclic glucan containing 18 glucose residues that can be substituted by one to seven succinyl esters residues ... | 2002 | 12027884 |
| assessment of a simple, non-toxic alamar blue cell survival assay to monitor tomato cell viability. | the alamar blue (ab) assay, which incorporates a medox indicator that changes colour or fluorescence in response to metabolic activity, is commonly used to assess quantitatively the viability and/or proliferation of mammalian cells and micro-organisms. in this study the ab assay was adapted for the determination of the viability of plant cells. cell suspension cultures of tomato, lycopersicon esculentum, l., with differing viabilities, served as the experimental model for a comparison of the ab ... | 2001 | 11705263 |
| genetic dissection of ralstonia solanacearum hrp gene cluster reveals that the hrpv and hrpx proteins are required for hrp pilus assembly. | in both plant and mammalian gram-negative pathogenic bacteria, type iii secretion systems (ttsss) play a crucial role in interactions with the host. all these systems share conserved proteins (called hrc in plant pathogens), but each bacterium also produces a variable number of additional type iii proteins either unique or with counterparts only in a limited number of related systems. in order to investigate the role of the different proteins encoded by the hrp gene cluster of the phytopathogeni ... | 2002 | 12046592 |
| genetic locus encoding functions involved in biosynthesis and outer membrane localization of xanthomonadin in xanthomonas oryzae pv. oryzae. | xanthomonadins are membrane-bound, brominated, aryl-polyene pigments specific to the genus xanthomonas. we have characterized a genetic locus (pig) from xanthomonas oryzae pv. oryzae which contains four open reading frames (orfs) that are essential for xanthomonadin production. three of these orfs are homologous to acyl carrier proteins, dehydratases, and acyl transferases, suggesting a type ii polyketide synthase pathway for xanthomonadin biosynthesis. the fourth orf has no homologue in the dat ... | 2002 | 12057948 |
| substrate specificity of nickel/cobalt permeases: insights from mutants altered in transmembrane domains i and ii. | hoxn, a high-affinity, nickel-specific permease of ralstonia eutropha h16, and nhlf, a nickel/cobalt permease of rhodococcus rhodochrous j1, are structurally related members of the nickel/cobalt transporter (nicot) family. these transporters have an eight-helix structure and are characterized by highly conserved segments with polar or charged amino acid residues in transmembrane domains (tmds) ii, iii, v, and vi. two histidine residues in a ni2+ binding motif, the signature sequence of nicots, i ... | 2002 | 12057951 |
| pcr-based detection and identification of burkholderia cepacia complex pathogens in sputum from cystic fibrosis patients. | pcr amplification of the reca gene followed by restriction fragment length polymorphism (rflp) analysis was investigated for the rapid detection and identification of burkholderia cepacia complex genomovars directly from sputum. successful amplification of the b. cepacia complex reca gene from cystic fibrosis (cf) patient sputum samples containing b. cepacia genomovar i, burkholderia multivorans, b. cepacia genomovar iii, burkholderia stabilis, and burkholderia vietnamiensis was demonstrated. in ... | 2001 | 11724828 |
| one case each of recurrent meningitis and hemoperitoneum infection with ralstonia mannitolilytica. | two clinical cases of infection with ralstonia mannitolilytica are described: a recurrent meningitis on an implanted intraventricular catheter and an infected hemoperitoneum as a complication of a cholangiocarcinoma. the strains were first misidentified as pseudomonas fluorescens and burkholderia cepacia. further testing lead to the identification as ralstonia pickettii biovar 3/"thomasii," which was recently shown to represent a separate species, r. mannitolilytica (list editor n. weiss, int. j ... | 2001 | 11724893 |
| a polyphasic approach for studying the interaction between ralstonia solanacearum and potential control agents in the tomato phytosphere. | ralstonia solanacearum biovar 2, the causative agent of brown rot in potato, has been responsible for large crop losses in northwest europe during the last decade. knowledge on the ecological behaviour of r. solanacearum and its antagonists is required to develop sound procedures for its control and eradication in infested fields.a polyphasic approach was used to study the invasion of plants by a selected r. solanacearum biovar 2 strain, denoted 1609, either or not in combination with the antago ... | 2002 | 11733083 |
| a local accumulation of the ralstonia solanacearum popa protein in transgenic tobacco renders a compatible plant-pathogen interaction incompatible. | plants activate disease resistance responses when they recognize pathogen-derived molecules (elicitors). frequently, recognition results in a hypersensitive response (hr), which is characterized by local host cell death at the infection site. here we describe a genetic engineering approach to generate an hr in plants, whether or not an invading micro-organism produces a recognized elicitor. to that aim we created transgenic tobacco plants in which the pathogen-inducible promoter of the hsr203j g ... | 2001 | 11737779 |
| twitching motility of ralstonia solanacearum requires a type iv pilus system. | twitching motility is a form of bacterial translocation over firm surfaces that requires retractile type iv pili. microscopic colonies of ralstonia solanacearum strains aw1, k60 and gmi1000 growing on the surface of a rich medium solidified with 1.6% agar appeared to exhibit twitching motility, because early on they divided into motile 'rafts' of cells and later developed protruding 'spearheads' at their margins. individual motile bacteria were observed only when they were embedded within masses ... | 2001 | 11739754 |
| molecular cloning and sequencing of the gene encoding an exopolygalacturonase of a bacillus isolate and properties of its recombinant enzyme. | an exopolygalacturonase (exo-pgase; ec 3.2.1.82) was found in the culture broth of a bacillus isolate. the gene encoding the exo-pgase, pehk, was cloned by polymerase chain reaction using mixed primers designed from n-terminal and internal amino acid (aa) sequences of the enzyme (pehk). the determined nucleotide (nt) sequence of pehk revealed a 2940 bp open reading frame (980 aa) that encoded a putative signal sequence (27 aa) and a mature protein (953 aa; 103810 da). the recombinant enzyme was ... | 2001 | 11750764 |
| chromosomal locus that affects pathogenicity of rhodococcus fascians. | the gram-positive plant pathogen rhodococcus fascians provokes leafy gall formation on a wide range of plants through secretion of signal molecules that interfere with the hormone balance of the host. crucial virulence genes are located on a linear plasmid, and their expression is tightly controlled. a mutant with a mutation in a chromosomal locus that affected virulence was isolated. the mutation was located in gene vica, which encodes a malate synthase and is functional in the glyoxylate shunt ... | 2002 | 11807072 |
| a r2r3-myb gene, atmyb30, acts as a positive regulator of the hypersensitive cell death program in plants in response to pathogen attack. | hypersensitive response (hr) is a programmed cell death that is commonly associated with disease resistance in plants. among the different hr-related early induced genes, the atmyb30 gene is specifically, rapidly, and transiently expressed during incompatible interactions between arabidopsis and bacterial pathogens. its expression was also shown to be deregulated in arabidopsis mutants affected in the control of cell death initiation. here, we demonstrate that overexpression in arabidopsis and t ... | 2002 | 12119395 |
| vibrio cholerae cytr is a repressor of biofilm development. | vibrio cholerae is both a human pathogen and a natural inhabitant of aquatic environments. in the aquatic environment, microorganisms are found attached to surfaces in structures known as biofilms. we have identified a transcriptional repressor in v. cholerae that inhibits exopolysaccharide synthesis and biofilm development. our studies show that this repressor is the v. cholerae homologue of escherichia coli cytr, a protein that represses nucleoside uptake and catabolism when nucleosides are sc ... | 2002 | 12123457 |
| quorum-sensing signals and quorum-sensing genes in burkholderia vietnamiensis. | acyl-homoserine lactone (acyl-hsl) quorum sensing is common to many proteobacteria including a clinical isolate of burkholderia cepacia. the b. cepacia isolate produces low levels of octanoyl-hsl. we have examined an environmental isolate of burkholderia vietnamiensis. this isolate produced several acyl-hsls. the most abundant species was decanoyl-hsl. decanoyl-hsl in b. vietnamiensis cultures reached concentrations in excess of 20 microm. we isolated a b. vietnamiensis dna fragment containing a ... | 2002 | 11807080 |
| mutational analysis of the tola c-terminal domain of escherichia coli and genetic evidence for an interaction between tola and tolb. | the tol proteins are involved in the outer membrane stability of gram-negative bacteria. the c-terminal domain of tola was mutagenized to identify residues important for its functions. the isolation of suppressor mutants of tola mutations in the tolb gene confirmed an interaction between tolaiii and the n-terminal domain of tolb. | 2002 | 12142433 |
| genome sequence of the plant pathogen ralstonia solanacearum. | ralstonia solanacearum is a devastating, soil-borne plant pathogen with a global distribution and an unusually wide host range. it is a model system for the dissection of molecular determinants governing pathogenicity. we present here the complete genome sequence and its analysis of strain gmi1000. the 5.8-megabase (mb) genome is organized into two replicons: a 3.7-mb chromosome and a 2.1-mb megaplasmid. both replicons have a mosaic structure providing evidence for the acquisition of genes throu ... | 2002 | 11823852 |
| relationships within the proteobacteria of plant pathogenic acidovorax species and subspecies, burkholderia species, and herbaspirillum rubrisubalbicans by sequence analysis of 16s rdna, numerical analysis and determinative tests. | sequence data for 16s rdna of the type strains of acidovorax avenae subsp. avenae, a. avenae subsp. cattleyae, a. avenae subsp. citrulli, a. konjaci and herbaspirillum rubrisubalbicans were compared with genbank library accessions of burkholderia spp., comamonas sp., ralstonia solanacearum and variovorax sp. maximum parsimony analysis produced two clusters: 1. acidovorax spp., comamonas sp., and variovorax sp. (all in the comamonadaceae), and 2. burkholderia spp., ralstonia solanacearum, and her ... | 2001 | 11827206 |
| resistance to ralstonia solanacearum in arabidopsis thaliana is conferred by the recessive rrs1-r gene, a member of a novel family of resistance genes. | the identification of two arabidopsis thaliana genes involved in determining recessive resistance to several strains of the causal agent of bacterial wilt, ralstonia solanacearum, is reported. dominant (rrs1-s) and recessive (rrs1-r) alleles from susceptible and resistant accessions encode highly similar predicted proteins differing in length and which present a novel structure combining domains found in plant toll-il-1 receptor-nucleotide binding site-leucin-rich repeat resistance proteins and ... | 2002 | 11842188 |
| reduction of olive knot disease by a bacteriocin from pseudomonas syringae pv. ciccaronei. | a bacteriocin produced by pseudomonas syringae pv. ciccaronei, used at different purification levels and concentrations in culture and in planta, inhibited the multiplication of p. syringae subsp. savastanoi, the causal agent of olive knot disease, and affected the epiphytic survival of the pathogen on the leaves and twigs of treated olive plants. treatments with bacteriocin from p. syringae pv. ciccaronei inhibited the formation of overgrowths on olive plants caused by p. syringae subsp. savast ... | 2002 | 11872493 |
| r391: a conjugative integrating mosaic comprised of phage, plasmid, and transposon elements. | the conjugative, chromosomally integrating element r391 is the archetype of the incj class of mobile genetic elements. originally found in a south african providencia rettgeri strain, r391 carries antibiotic and mercury resistance traits, as well as genes involved in mutagenic dna repair. while initially described as a plasmid, r391 has subsequently been shown to be integrated into the bacterial chromosome, employing a phage-like integration mechanism closely related to that of the sxt element f ... | 2002 | 12193633 |
| staphylococcus aureus contains two low-molecular-mass phosphotyrosine protein phosphatases. | the analysis of the different amino acid sequences deduced from the complete genome sequence of the gram-positive bacterium staphylococcus aureus suggested the presence of two eukaryotic-protein-like low-molecular-mass phosphotyrosine protein phosphatases, which are usually found in gram-negative bacteria. to check this prediction, the corresponding genes were cloned and overexpressed in an escherichia coli system. two distinct proteins with an apparent molecular mass of 23 kda each, ptpa and pt ... | 2002 | 12193638 |
| a two-component regulator mediates population-density-dependent expression of the bradyrhizobium japonicum nodulation genes. | bradyrhizobium japonicum nod gene expression was previously shown to be population density dependent. induction of the nod genes is highest at low culture density and repressed at high population densities. this repression involves both nola and nodd2 and is mediated by an extracellular factor found in b. japonicum conditioned medium. nola and nodd2 expression is maximal at high population densities. we demonstrate here that a response regulator, encoded by nwsb, is required for the full express ... | 2002 | 11872728 |
| a signal transfer system through three compartments transduces the plant cell contact-dependent signal controlling ralstonia solanacearum hrp genes. | ralstonia solanacearum hrp genes encode a type iii secretion system required for disease development in host plants and for hypersensitive response elicitation on non-hosts. hrp genes are expressed in the presence of plant cells through the hrpb regulator. this activation, which requires physical interaction between the bacteria and the plant cell, is sensed by the outer membrane receptor prha. prha transduces the plant cell contact-dependent signal through a complex regulatory cascade integrate ... | 2002 | 11876423 |
| type iii secretion systems and the evolution of mutualistic endosymbiosis. | the view that parasites can develop cooperative symbiotic relationships with their hosts is both appealing and widely held; however, there is no molecular genetic evidence of such a transition. here we demonstrate that a mutualistic bacterial endosymbiont of grain weevils maintains and expresses inv/spa genes encoding a type iii secretion system homologous to that used for invasion by bacterial pathogens. phylogenetic analyses indicate that inv/spa genes were present in presymbiotic ancestors of ... | 2002 | 12213957 |
| metabolic signals that lead to control of cbb gene expression in rhodobacter capsulatus. | various mutant strains were used to examine the regulation and metabolic control of the calvin-benson-bassham (cbb) reductive pentose phosphate pathway in rhodobacter capsulatus. previously, a ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco)-deficient strain (strain sbi/ii) was found to show enhanced levels of cbb(i) and cbb(ii) promoter activities during photoheterotrophic growth in the presence of dimethyl sulfoxide. with this strain as the starting point, additional mutations were ma ... | 2002 | 11889097 |
| characterization of an acyltransferase capable of synthesizing benzylbenzoate and other volatile esters in flowers and damaged leaves of clarkia breweri. | a cdna encoding a protein with 456 amino acids whose sequence shows considerable similarity to plant acyltransferases was identified among 750 clarkia breweri flower expressed sequence tags. the cdna was expressed in escherichia coli, and the protein produced was shown to encode the enzyme benzoyl-coenzyme a (coa):benzyl alcohol benzoyl transferase (bebt). bebt catalyzes the formation of benzylbenzoate, a minor constituent of the c. breweri floral aroma, but it also has activity with a number of ... | 2002 | 12226525 |
| amplification of rna by nasba allows direct detection of viable cells of ralstonia solanacearum in potato. | the objective of this study was to develop a nucleic acid sequence based amplification (nasba) assay, targeting 16s rrna sequences, for direct detection of viable cells of ralstonia solanacearum, the causal organism of bacterial wilt. the presence of intact 16s rrna is considered to be a useful indicator for viability, as a rapid degradation of this target molecule is found upon cell death. | 2002 | 12234348 |
| heca, a member of a class of adhesins produced by diverse pathogenic bacteria, contributes to the attachment, aggregation, epidermal cell killing, and virulence phenotypes of erwinia chrysanthemi ec16 on nicotiana clevelandii seedlings. | erwinia chrysanthemi is representative of a broad class of bacterial pathogens that are capable of inducing necrosis in plants. the e. chrysanthemi ec16 heca gene predicts a 3,850-aa member of the bordetella pertussis filamentous hemagglutinin family of adhesins. a hecatn7 mutant was reduced in virulence on nicotiana clevelandii seedlings after inoculation without wounding. epifluorescence and confocal laser-scanning microscopy observations of heca and wild-type cells expressing the green fluore ... | 2002 | 12271135 |
| the exopolyphosphatase gene from sulfolobus solfataricus: characterization of the first gene found to be involved in polyphosphate metabolism in archaea. | inorganic polyphosphate (polyp) polymers are widely distributed in all kinds of organisms. although the presence of polyp in members of the domain archaea has been described, at present nothing is known about the enzymology of polyp metabolism or the genes involved in this domain. we have cloned, sequenced, and overexpressed an exopolyphosphatase (ppx) gene (ppx) from thermophilic sulfolobus solfataricus. the gene codes for a functional ppx and possesses an open reading frame for 417 amino acids ... | 2002 | 12324325 |
| polyphosphate kinase from activated sludge performing enhanced biological phosphorus removal. | a novel polyphosphate kinase (ppk) was retrieved from an uncultivated organism in activated sludge carrying out enhanced biological phosphorus removal (ebpr). acetate-fed laboratory-scale sequencing batch reactors were used to maintain sludge with a high phosphorus content (approximately 11% of the biomass). pcr-based clone libraries of small subunit rrna genes and fluorescent in situ hybridization (fish) were used to verify that the sludge was enriched in rhodocyclus-like beta-proteobacteria kn ... | 2002 | 12324346 |
| snakin-2, an antimicrobial peptide from potato whose gene is locally induced by wounding and responds to pathogen infection. | the peptide snakin-2 (stsn2) has been isolated from potato (solanum tuberosum cv jaerla) tubers and found to be active (ec(50) = 1-20 microm) against fungal and bacterial plant pathogens. it causes a rapid aggregation of both gram-positive and gram-negative bacteria. the corresponding stsn2 cdna encodes a signal sequence followed by a 15-residue acidic sequence that precedes the mature stsn2 peptide, which is basic (isoelectric point = 9.16) and 66 amino acid residues long (molecular weight of 7 ... | 2002 | 11891250 |
| characterization of a brucella species 25-kilobase dna fragment deleted from brucella abortus reveals a large gene cluster related to the synthesis of a polysaccharide. | in the present study we completed the nucleotide sequence of a brucella melitensis 16m dna fragment deleted from b. abortus that accounts for 25,064 bp and show that the other brucella spp. contain the entire 25-kb dna fragment. two short direct repeats of four nucleotides, detected in the b. melitensis 16m dna flanking both sides of the fragment deleted from b. abortus, might have been involved in the deletion formation by a strand slippage mechanism during replication. in addition to omp31, co ... | 2001 | 11598046 |
| conservation of the biotin regulon and the bira regulatory signal in eubacteria and archaea. | biotin is a necessary cofactor of numerous biotin-dependent carboxylases in a variety of microorganisms. the strict control of biotin biosynthesis in escherichia coli is mediated by the bifunctional bira protein, which acts both as a biotin-protein ligase and as a transcriptional repressor of the biotin operon. little is known about regulation of biotin biosynthesis in other bacteria. using comparative genomics and phylogenetic analysis, we describe the biotin biosynthetic pathway and the bira r ... | 2002 | 12368242 |
| a widely conserved bacterial cell division protein that promotes assembly of the tubulin-like protein ftsz. | cell division in bacteria is mediated by the tubulin-like protein ftsz, which assembles into a structure known as the z ring at the future site of cytokinesis. we report the discovery of a z-ring-associated protein in bacillus subtilis called zapa. zapa was found to colocalize with the z ring in vivo and was capable of binding to ftsz and stimulating the formation of higher-order assemblies of the cytokinetic protein in vitro. the absence of zapa alone did not impair cell viability, but the abse ... | 2002 | 12368265 |
| evidence of association of salmonellae with tomato plants grown hydroponically in inoculated nutrient solution. | the possibility of uptake of salmonellae by roots of hydroponically grown tomato plants was investigated. within 1 day of exposure of plant roots to hoagland nutrient solution containing 4.46 to 4.65 log(10) cfu of salmonellae/ml, the sizes of the pathogen populations were 3.01 cfu/g of hypocotyls and cotyledons and 3.40 log(10) cfu/g of stems for plants with intact root systems (control) and 2.55 log(10) cfu/g of hypocotyls and cotyledons for plants from which portions of the roots had been rem ... | 2002 | 12089054 |
| direct biochemical evidence for type iii secretion-dependent translocation of the avrbs2 effector protein into plant cells. | the calmodulin-dependent adenylate cyclase domain (cya) of the bordetella pertussis cyclolysin was used as a reporter protein to study the direct translocation of the xanthomonas effector protein, avrbs2, into the plant host cell. adenylate cyclase activity (production of camp) depends on the presence of eukaryotic plant calmodulin and is only active after translocation from the prokaryotic cell into the eukaryotic plant cell. here, we show that infection of pepper plants by xanthomonas campestr ... | 2002 | 12060777 |
| the crystal structure of hypothetical protein mth1491 from methanobacterium thermoautotrophicum. | as part of our structural proteomics initiative, we have determined the crystal structure of mth1491, a previously uncharacterized hypothetical protein from methanobacterium thermoautotrophicum. mth1491 is one of numerous structural genomics targets selected in a genome-wide survey of uncharacterized proteins. it belongs to a family of proteins whose biological function is not known. the crystal structure of mth1491, the first structure for this family of proteins, consists of an overall five-st ... | 2002 | 12021439 |
| molecular method to assess the diversity of burkholderia species in environmental samples. | in spite of the importance of many members of the genus burkholderia in the soil microbial community, no direct method to assess the diversity of this genus has been developed so far. the aim of this work was the development of soil dna-based pcr-denaturing gradient gel electrophoresis (dgge), a powerful tool for studying the diversity of microbial communities, for detection and analysis of the burkholderia diversity in soil samples. primers specific for the genus burkholderia were developed bas ... | 2002 | 11916673 |
| [chemical characterisation and serological activity of lipopolysaccharides of ralstonia solanacearum]. | lipopolysaccharides (lps) of 8 strains of ralstonia solanacearum (767, 4157, 5712, 7944, 7945, 7955, 8089 and 8110) characterized by different types of the structures of o-specific polysaccharide chains have been investigated. the elisa and elisa-inhibition methods were used to investigate the extent of antigenic activity of the presented lps with respect to the obtained polyclonal o-antisera to the above strains. when analyzing the results obtained the strains were divided into five serogroups ... | 2002 | 11944345 |
| ocatin. a novel tuber storage protein from the andean tuber crop oca with antibacterial and antifungal activities. | the most abundant soluble tuber protein from the andean crop oca (oxalis tuberosa mol.), named ocatin, has been purified and characterized. ocatin accounts for 40% to 60% of the total soluble oca tuber proteins, has an apparent molecular mass of 18 kd and an isoelectric point of 4.8. this protein appears to be found only in tubers and is accumulated only within the cells of the pith and peridermis layers (peel) of the tuber as it develops. ocatin inhibits the growth of several phytopathogenic ba ... | 2002 | 11950978 |
| opportunistic colonization of ralstonia solanacearum-infected plants by acinetobacter sp. and its natural competence development. | the behavior of the soil bacterium acinetobacter sp. bd413 was monitored in ralstonia solanacearum-infected and non-infected tomato plants after direct injection into the stem or natural infection by roots. in healthy plants, acinetobacter sp. bd413 failed to colonize plant tissue. in plants infected simultaneously by the pathogen r. solanacearum,the acinetobacter population increased linearly to about 3.1 x 10(7) cells per gram plant material and was maintained at a high level until the death o ... | 2002 | 12037607 |
| getting across--bacterial type iii effector proteins on their way to the plant cell. | pathogenicity of most gram-negative bacterial plant pathogens depends on hrp (hypersensitive response and pathogenicity) genes, which control the ability to cause disease and to elicit specific defense responses in resistant plants. hrp genes encode a specialized type iii secretion (tts) system that mediates the vectorial delivery of bacterial effector proteins across both bacterial membranes as well as across the eukaryotic plasma membrane into the host cell cytosol. one well-studied effector p ... | 2002 | 12374732 |
| secondary (gamma-proteobacteria) endosymbionts infect the primary (beta-proteobacteria) endosymbionts of mealybugs multiple times and coevolve with their hosts. | mealybugs (hemiptera, coccoidea, pseudococcidae) are plant sap-sucking insects that have within their body cavities specialized cells containing prokaryotic primary endosymbionts (p-endosymbionts). the p-endosymbionts have the unusual property of containing within their cytoplasm prokaryotic secondary endosymbionts (s-endosymbionts) [c. d. von dohlen, s. kohler, s. t. alsop, and w. r. mcmanus, nature (london) 412:433-436, 2001]. four-kilobase fragments containing 16s-23s ribosomal dna (rdna) wer ... | 2002 | 12088994 |
| the genetic properties of the primary endosymbionts of mealybugs differ from those of other endosymbionts of plant sap-sucking insects. | mealybugs (hemiptera, coccoidea, pseudococcidae), like aphids and psyllids, are plant sap-sucking insects that have an obligate association with prokaryotic endosymbionts that are acquired through vertical, maternal transmission. we sequenced two fragments of the genome of tremblaya princeps, the endosymbiont of mealybugs, which is a member of the beta subdivision of the proteobacteria. each of the fragments (35 and 30 kb) contains a copy of 16s-23s-5s rrna genes. a total of 37 open reading fram ... | 2002 | 12088995 |
| in situ transfer of antibiotic resistance genes from transgenic (transplastomic) tobacco plants to bacteria. | interkingdom gene transfer is limited by a combination of physical, biological, and genetic barriers. the results of greenhouse experiments involving transplastomic plants (genetically engineered chloroplast genomes) cocolonized by pathogenic and opportunistic soil bacteria demonstrated that these barriers could be eliminated. the acinetobacter sp. strain bd413, which is outfitted with homologous sequences to chloroplastic genes, coinfected a transplastomic tobacco plant with ralstonia solanacea ... | 2002 | 12089013 |
| enrichment double-antibody sandwich indirect enzyme-linked immunosorbent assay that uses a specific monoclonal antibody for sensitive detection of ralstonia solanacearum in asymptomatic potato tubers. | sensitive and specific routine detection of ralstonia solanacearum in symptomless potato tubers was achieved by efficient enrichment followed by a reliable double-antibody sandwich indirect enzyme-linked immunosorbent assay based on the specific monoclonal antibody 8b-ivia. this monoclonal antibody reacted with 168 typical r. solanacearum strains and did not recognize 174 other pathogenic or unidentified bacteria isolated from potato. the optimized protocol included an initial enrichment step co ... | 2002 | 12089053 |
| altering plant-microbe interaction through artificially manipulating bacterial quorum sensing. | many bacteria regulate diverse physiological processes in concert with their population size. bacterial cell-to-cell communication utilizes small diffusible signal molecules, which the bacteria both produce and perceive. the bacteria couple gene expression to cell density by eliciting a response only when the signalling molecules reach a critical threshold (a point at which the population is said to be 'quorate'). the population as a whole is thus able to modify its behaviour as a single unit. a ... | 2002 | 12096736 |
| the role of lineage-specific gene family expansion in the evolution of eukaryotes. | a computational procedure was developed for systematic detection of lineage-specific expansions (lses) of protein families in sequenced genomes and applied to obtain a census of lses in five eukaryotic species, the yeasts saccharomyces cerevisiae and schizosaccharomyces pombe, the nematode caenorhabditis elegans, the fruit fly drosophila melanogaster, and the green plant arabidopsis thaliana. a significant fraction of the proteins encoded in each of these genomes, up to 80% in a. thaliana, belon ... | 2002 | 12097341 |
| regulation of riboflavin biosynthesis and transport genes in bacteria by transcriptional and translational attenuation. | the riboflavin biosynthesis in bacteria was analyzed using comparative analysis of genes, operons and regulatory elements. a model for regulation based on formation of alternative rna structures involving the rfn elements is suggested. in gram-positive bacteria including actinomycetes, thermotoga, thermus and deinococcus, the riboflavin metabolism and transport genes are predicted to be regulated by transcriptional attenuation, whereas in most gram-negative bacteria, the riboflavin biosynthesis ... | 2002 | 12136096 |
| chlorxanthomycin, a fluorescent, chlorinated, pentacyclic pyrene from a bacillus sp. | a gram-positive bacillus sp. that fluoresces yellow under long-wavelength uv light on several common culture media was isolated from soil samples. on the basis of carbon source utilization studies, fatty acid methyl ester analysis, and 16s ribosomal dna analysis, this bacterium was most similar to bacillus megaterium. chemical extraction yielded a yellow-orange fluorescent pigment, which was characterized by x-ray crystallography, mass spectrometry, and nuclear magnetic resonance spectroscopy. t ... | 2002 | 12147512 |
| comparative genomic analysis of plant-associated bacteria. | this review deals with a comparative analysis of seven genome sequences from plant-associated bacteria. these are the genomes of agrobacterium tumefaciens, mesorhizobium loti, sinorhizobium meliloti, xanthomonas campestris pv campestris, xanthomonas axonopodis pv citri, xylella fastidiosa, and ralstonia solanacearum. genome structure and the metabolism pathways available highlight the compromise between the genome size and lifestyle. despite the recognized importance of the type iii secretion sy ... | 2002 | 12147758 |
| production, properties and specificity of a new bacterial l-fucose- and d-arabinose-binding lectin of the plant aggressive pathogen ralstonia solanacearum, and its comparison to related plant and microbial lectins. | the worldwide distributed plant aggressive pathogen ralstonia solanacearum, which causes lethal wilt in many agricultural crops, produces a potent l-fucose-binding lectin (rsl) exhibiting sugar specificity similar to that of pa-iil of the human aggressive opportunistic pathogen pseudomonas aeruginosa. both lectins show l-fucose > l-galactose > d-arabinose > d-mannose specificity, but the affinities of rsl to these sugars are substantially lower. unlike ulex europaeus anti-h lectin, but like pa-i ... | 2002 | 12153735 |
| [the study of bacterial glycopolymers using laser spectroscopy]. | a possibility has been demonstrated to use laser spectroscopy of bacterial glycopolymers by means of measurement of their water solutions fluorescence. comparative investigations of native lipopolysaccharide (lps) ralstonia solanacearum and its structure components permits a supposition to be made that the lps total spectrum is a result of superposition of the spectrum of o-specific polysaccharide and core oligosaccharide as well as core oligosaccharide and lipid a. the lps spectrum maximum shif ... | 2002 | 12190019 |