| arabidopsis rtm2 gene is necessary for specific restriction of tobacco etch virus and encodes an unusual small heat shock-like protein. | arabidopsis plants have a system to specifically restrict the long-distance movement of tobacco etch potyvirus (tev) without involving either hypersensitive cell death or systemic acquired resistance. at least two dominant genes, rtm1 and rtm2, are necessary for this restriction. through a series of coinfection experiments with heterologous viruses, the rtm1/rtm2-mediated restriction was shown to be highly specific for tev. the rtm2 gene was isolated by a map-based cloning strategy. isolation of ... | 2000 | 10760245 |
| genetic analysis of functions involved in adhesion of pseudomonas putida to seeds. | many agricultural uses of bacteria require the establishment of efficient bacterial populations in the rhizosphere, for which colonization of plant seeds often constitutes a critical first step. pseudomonas putida kt2440 is a strain that colonizes the rhizosphere of a number of agronomically important plants at high population densities. to identify the functions involved in initial seed colonization by p. putida kt2440, we subjected this strain to transposon mutagenesis and screened for mutants ... | 2000 | 10762233 |
| mechanism, regulation, and ecological role of bacterial cyanide biosynthesis. | a few bacterial species are known to produce and excrete hydrogen cyanide (hcn), a potent inhibitor of cytochrome c oxidase and several other metalloenzymes. in the producer strains, hcn does not appear to have a role in primary metabolism and is generally considered a secondary metabolite. hcn synthase of proteobacteria (especially fluorescent pseudomonads) is a membrane-bound flavoenzyme that oxidizes glycine, producing hcn and co2. the hcnabc structural genes of pseudomonas fluorescens and p. ... | 2000 | 10763748 |
| involvement of the respiratory chain of gram-negative bacteria in the reduction of tellurite. | the terminal oxidases of the respiratory chain of seven strains of gram-negative bacteria were shown to be involved in the reduction of tellurite. the rate of tellurite reduction correlated with the intensity of respiration. the inhibitors of terminal oxidases, carbon monoxide and cyanide, inhibited the reduction of tellurite. in pseudomonas aeruginosa pao ml4262 and p. aeruginosa pao ml4262 (pbs 10), the respiratory chain was found to contain three types of cytochrome c, one of which (the carbo ... | 2000 | 10763749 |
| automated surgical equipment requires routine disinfection of vacuum control manifold to prevent postoperative endophthalmitis. | contamination of automated surgical equipment is a potential source of postoperative endophthalmitis. the effect of disinfecting the unsterile vacuum control manifold (vcm) on contamination of the aspiration fluid was studied. | 2000 | 10768329 |
| rpma is required for nonopsonic phagocytosis of pseudomonas aeruginosa. | pseudomonas aeruginosa causes severe respiratory tract infections in patients with cystic fibrosis (cf). we have been examining nonopsonic phagocytosis of p. aeruginosa by macrophages. to study the p. aeruginosa-macrophage interaction at the molecular level, we have constructed a transposon tn5g bank in a clinical isolate of p. aeruginosa (strain 4020) and identified mutants resistant to nonopsonic phagocytosis. phagocytosis-resistant mutants were enriched by passaging the transposon bank over 1 ... | 2000 | 10768936 |
| the complete dna sequence and analysis of r27, a large inchi plasmid from salmonella typhi that is temperature sensitive for transfer. | salmonella typhi, the causative agent of typhoid fever, annually infects 16 million people and kills 600 000 world wide. plasmid-encoded multiple drug resistance in s. typhi is always encoded by plasmids of incompatibility group h (inch). the complete dna sequence of the large temperature-sensitive conjugative plasmid r27, the prototype for the inchi1 family of plasmids, has been compiled and analyzed. this 180 kb plasmid contains 210 open reading frames (orfs), of which 14 have been previously ... | 2000 | 10773089 |
| overexpression of arabidopsis thaliana skp1 homologues in yeast inactivates the mig1 repressor by destabilising the f-box protein grr1. | the timed destruction of cell cycle regulatory proteins is of key importance in controlling cell cycle progression in eukaryotes. recently, skp1 from yeast (saccharomyces cerevisiae) was shown to play an important role in the ubiquitin-mediated proteolysis of these proteins via the skp1-cdc53-f-box (scf) pathway. here we describe the fortuitous cloning of cdnas for two skp1 homologues from the plant arabidopsis thaliana on account of their ability to activate reporter gene expression in yeast di ... | 2000 | 10778750 |
| enzymology of type iv macromolecule secretion systems: the conjugative transfer regions of plasmids rp4 and r388 and the cag pathogenicity island of helicobacter pylori encode structurally and functionally related nucleoside triphosphate hydrolases. | type iv secretion systems direct transport of protein or nucleoprotein complexes across the cell envelopes of prokaryotic donor and eukaryotic or prokaryotic recipient cells. the process is mediated by a membrane-spanning multiprotein assembly. potential ntpases belonging to the virb11 family are an essential part of the membrane-spanning complex. three representatives of these ntpases originating from the conjugative transfer regions of plasmids rp4 (trbb) and r388 (trwd) and from the cag patho ... | 2000 | 10781544 |
| luxr- and acyl-homoserine-lactone-controlled non-lux genes define a quorum-sensing regulon in vibrio fischeri. | the luminescence (lux) operon (luxicdabeg) of the symbiotic bacterium vibrio fischeri is regulated by the transcriptional activator luxr and two acyl-homoserine lactone (acyl-hsl) autoinducers (the luxi-dependent 3-oxo-hexanoyl-hsl [3-oxo-c6-hsl] and the ains-dependent octanoyl-hsl [c8-hsl]) in a population density-responsive manner called quorum sensing. to identify quorum-sensing-regulated (qsr) proteins different from those encoded by lux genes, we examined the protein patterns of v. fischeri ... | 2000 | 10781550 |
| the arcb sensor kinase of escherichia coli: genetic exploration of the transmembrane region. | the arc two-component signal transduction system of escherichia coli regulates the expression of numerous operons in response to respiratory growth conditions. cellular redox state or proton motive force (delta(h(+))) has been proposed to be the signal for the membrane-associated arcb sensor kinase. this study provided evidence for a short arcb periplasmic bridge that contains a his47. the dispensability of this amino acid, the only amino acid with a pk in the physiological range, renders the de ... | 2000 | 10781568 |
| establishment of forskolin yielding transformed cell suspension cultures of coleus forskohlii as controlled by different factors. | suspension cultures derived from gall calli which were obtained following infection with agrobacterium tumefaciens (c58) were established in coleus forskohlii. cell line selection following single cell cloning or cell aggregate cloning was carried out to select cell lines capable of fast growth and for producing high level of forskolin. a fast growing cell line (gso-5/7) thus selected was found to accumulate 0.021% forskolin in 42 days. the effect of cultural conditions on cell growth was studie ... | 2000 | 10784298 |
| a region of the agrobacterium tumefaciens chromosome containing genes required for virulence and attachment to host cells. | a 29 kb region of the circular chromosome of agrobacterium tumefaciens containing genes required for bacterial attachment to host cells and virulence has been sequenced. transposon mutants in many of the genes have been obtained. the mutants can be divided into two groups: those which can be complemented by conditioned medium and those whose phenotype is unaffected by conditioned medium. the first group includes mutants in genes with homology to abc transporters, one possible transcriptional reg ... | 2000 | 10786639 |
| characterization of plasmid-borne and chromosome-encoded traits of agrobacterium biovar 1, 2, and 3 strains from france. | we collected 111 agrobacterium isolates from galls of various origins (most of them from france) and analyzed both their plasmid-borne and chromosome-encoded traits. phenotypic analysis of these strains allowed their classification in three phena which exactly matched the delineation of biovars 1, 2, and 3. a fourth phenon was identified which comprises three atypical strains. the phenotypic analysis has also allowed us to identify 12 additional characteristics which could be used to identify th ... | 2000 | 10788345 |
| enantiomeric degradation of 2-(4-sulfophenyl)butyrate via 4-sulfocatechol in delftia acidovorans spb1. | enrichment cultures with enantiomeric 2-(4-sulfophenyl)butyrate (spb) as the sole added source(s) of carbon and energy for growth yielded a pure culture of a degradative bacterium, which was identified as delftia acidovorans spb1. the organism utilized the enantiomers sequentially. r-spb was utilized first (specific growth rate [mu] = 0.28 h(-1)), with transient excretion of an unknown intermediate, which was identified as 4-sulfocatechol (4sc). utilization of s-spb was slower (mu = 0.016 h(-1)) ... | 2000 | 10788358 |
| development of a highly sensitive nested-pcr procedure using a single closed tube for detection of erwinia amylovora in asymptomatic plant material. | a novel method, which involves a nested pcr in a single closed tube, was developed for the sensitive detection of erwinia amylovora in plant material. the external and internal primer pairs used had different annealing temperatures and directed the amplification of a specific dna fragment from plasmid pea29. the procedure involved two consecutive pcrs, the first of which was performed at a higher annealing temperature that allowed amplification only by the external primer pair. using pure cultur ... | 2000 | 10788384 |
| use of agrobacterium expressing green fluorescent protein to evaluate colonization of sonication-assisted agrobacterium-mediated transformation-treated soybean cotyledons. | colonization and infection of soybean cotyledons by agrobacterium tumefaciens and subsequent elimination of bacteria from cotyledons were monitored using bacteria expressing green fluorescent protein (gfp). gfp provided a quick, non-destructive method to evaluate, in real time, agrobacterium colonization of cotyledon surfaces as well as infection of internal cells. gfp was first detected 7 h following inoculation of the cotyledon. by 36 h, gfp expression was very intense, and was limited to the ... | 2000 | 10792672 |
| 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 |
| the yeast hal1 gene improves salt tolerance of transgenic tomato. | overexpression of the hal1 gene in yeast has a positive effect on salt tolerance by maintaining a high internal k(+) concentration and decreasing intracellular na(+) during salt stress. in the present work, the yeast gene hal1 was introduced into tomato (lycopersicon esculentum mill.) by agrobacterium tumefaciens-mediated transformation. a sample of primary transformants was self-pollinated, and progeny from both transformed and non-transformed plants (controls) were evaluated for salt tolerance ... | 2000 | 10806256 |
| structural elements required for replication and incompatibility of the rhizobium etli symbiotic plasmid. | the symbiotic plasmid of rhizobium etli ce3 belongs to the repabc family of plasmid replicons. this family is characterized by the presence of three conserved genes, repa, repb, and repc, encoded by the same dna strand. a long intergenic sequence (igs) between repb and repc is also conserved in all members of the plasmid family. in this paper we demonstrate that (i) the repabc genes are organized in an operon; (ii) the repc product is essential for replication; (iii) repa and repb products parti ... | 2000 | 10809690 |
| initiation and termination of dna transfer during conjugation of inci1 plasmid r64: roles of two sets of inverted repeat sequences within orit in termination of r64 transfer. | intercellular transfer of plasmid dna during bacterial conjugation initiates and terminates at a specific origin of transfer, orit. we have investigated the orit structure of conjugative plasmid r64 with regard to the initiation and termination of dna transfer. using recombinant plasmids containing two tandemly repeated r64 orit sequences with or without mutations, the subregions required for initiation and termination were determined by examining conjugation-mediated deletion between the repeat ... | 2000 | 10809699 |
| transgenic arabidopsis plants expressing a fungal cutinase show alterations in the structure and properties of the cuticle and postgenital organ fusions. | a major structural component of the cuticle of plants is cutin. analysis of the function of cutin in vivo has been limited because no mutants with specific defects in cutin have been characterized. therefore, transgenic arabidopsis plants were generated that express and secrete a cutinase from fusarium solani f sp pisi. arabidopsis plants expressing the cutinase in the extracellular space showed an altered ultrastructure of the cuticle and an enhanced permeability of the cuticle to solutes. in a ... | 2000 | 10810146 |
| 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 |
| expression of a chimeric farnesyl diphosphate synthase gene in artemisia annua l. transgenic plants via agrobacterium tumefaciens-mediated transformation. | an agrobacterium tumefaciens-mediated transformation system was developed for artemisia annua l. using this system a cdna encoding farnesyl diphosphate synthase (fds placed under a camv 35s promoter) was transferred into a. annua via a. tumefaciens strain lb4404. leaf or leaf discs were used as explants to be infected with a. tumefaciens and an optimal concentration of 20 mg/l kanamycin was applied to select kanamycin resistant shoots. forty-five lines of resistance kanamycin shoots transformed ... | 2000 | 10814821 |
| highly tumorigenic agrobacterium tumefaciens strain from crown gall tumors of chrysanthemum. | a wild-type agrobacterium tumefaciens strain cni5 isolated from crown gall of chrysanthemum (dendranthema grandiflora tzvelev) was characterized. strain cni5 was classified into biovar 1, based on physiological and biochemical characteristics, and was resistant to ampicillin. strain cni5 induced tumors at a higher frequency and on a larger area of explants in most tested plant species, especially in chrysanthemum cultivars, than the octopine-type strain c58c1cmr (ptib6s3). agropine and mannopine ... | 2000 | 10816052 |
| constitutive mutations of the salmonella enterica serovar typhimurium transcriptional virulence regulator phop. | the phop-phoq two-component system is necessary for the virulence of salmonella spp. and is responsible for regulating several modifications of the lipopolysaccharide (lps). mutagenesis of the transcriptional regulator phop resulted in the identification of a mutant able to activate transcription of regulated genes approximately 100-fold in the absence of phoq. sequence analysis showed two single-base alterations resulting in amino acid changes at positions 93 (s93n) and 203 (q203r). these mutat ... | 2000 | 10816543 |
| tyrosine residues serve as proton donor in the catalytic mechanism of epoxide hydrolase from agrobacterium radiobacter. | epoxide hydrolase from agrobacterium radiobacter catalyzes the hydrolysis of epoxides to their diols via an alkyl-enzyme intermediate. the recently solved x-ray structure of the enzyme shows that two tyrosine residues (tyr152 and tyr215) are positioned close to the nucleophile asp107 in such a way that they can serve as proton donor in the alkylation reaction step. the role of these tyrosines, which are conserved in other epoxide hydrolases, was studied by site-directed mutagenesis. mutation of ... | 2000 | 10820034 |
| development of a simple and efficient method for transformation of buckwheat plants (fagopyrum esculentum) using agrobacterium tumefaciens. | apical meristems of seedlings of buckwheat (fagopyrum esculentum var. shinano no. 1) were pricked with a needle and inoculated with agrobacterium tumefaciens (lba4404, pbi121). the inoculated seedlings were grown to maturation and allowed to pollinate randomly to set the seeds (t1 plants). the transformation efficiency of the t1 plants was estimated by germination in the presence of geneticin (20 microg/ml) and by detection of beta-glucuronidase (gus) gene with pcr, indicating that 36% and 70% o ... | 2000 | 10830503 |
| distribution of aldoxime dehydratase in microorganisms. | the distribution of phenylacetaldoxime-degrading and pyridine-3-aldoxime-degrading ability was examined with intact cells of 975 microorganisms, including 45 genera of bacteria, 11 genera of actinomyces, 22 genera of yeasts, and 37 genera of fungi, by monitoring the decrease of the aldoximes by high-pressure liquid chromatography. the abilities were found to be widely distributed in bacteria, actinomyces, fungi, and some yeasts: 98 and 107 strains degraded phenylacetaldoxime and pyridine-3-aldox ... | 2000 | 10831401 |
| 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 |
| 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 |
| genetic transformation of coccidioides immitis facilitated by agrobacterium tumefaciens. | agrobacterium tumefaciens was used to facilitate genetic transformation of coccidioides immitis. a gene cassette containing the gene encoding hygromycin phosphotransferase (hph) was cloned into a t-dna vector plasmid and introduced into a. tumefaciens, and the resultant strain was used for cocultivation with germinated arthroconidia. this procedure produced numerous colonies 60- to >500-fold more resistant to hygromycin than untransformed mycelia. both polymerase chain reaction and southern blot ... | 2000 | 10837205 |
| a unique virus complex causes ageratum yellow vein disease. | ageratum conyzoides l., a weed species widely distributed throughout southeast asia, frequently exhibits striking yellow vein symptoms associated with infection by ageratum yellow vein virus (ayvv), a member of the geminiviridae (genus begomovirus). most begomoviruses have bipartite genomes (dnas a and b), but only a dna a has been identified for ayvv. we demonstrate that yellow vein disease of a. conyzoides results from co-infection by ayvv dna a (2,741 nt) and a circular dna that is approximat ... | 2000 | 10841581 |
| subcellular localization of the agrobacterium tumefaciens t-dna transport pore proteins: virb8 is essential for the assembly of the transport pore. | agrobacterium tumefaciens transforms plants by transferring dna to the plant cell nucleus. the virb membrane proteins are postulated to form a pore for the transport of the dna across the bacterial membranes. immunofluorescence and immunoelectron microscopy were used to study the transport pore complex. three likely components of the transport pore, virb8, virb9 and virb10, localized primarily to the inner membrane, outer membrane and periplasm respectively. a significant amount of virb10 was al ... | 2000 | 10844650 |
| genetic and environmental factors affecting t-pilin export and t-pilus biogenesis in relation to flagellation of agrobacterium tumefaciens. | the t pilus, primarily composed of cyclic t-pilin subunits, is essential for the transmission of the ti-plasmid t-dna from agrobacterium tumefaciens to plant cells. although the virb2 gene of the 11-gene virb operon was previously demonstrated to encode the full-length propilin, and other genes of this operon have been implicated as members of a conserved transmembrane transport apparatus, the role of each virb gene in t-pilin synthesis and transport and t-pilus biogenesis remained undefined. in ... | 2000 | 10850985 |
| characterization of a snorhizobium meliloti atp-binding cassette histidine transporter also involved in betaine and proline uptake. | the symbiotic soil bacterium sinorhizobium meliloti uses the compatible solutes glycine betaine and proline betaine for both protection against osmotic stress and, at low osmolarities, as an energy source. a pcr strategy based on conserved domains in components of the glycine betaine uptake systems from escherichia coli (prou) and bacillus subtilis (opua and opuc) allowed us to identify a highly homologous atp-binding cassette (abc) binding protein-dependent transporter in s. meliloti. this syst ... | 2000 | 10850986 |
| the n- and c-terminal portions of the agrobacterium virb1 protein independently enhance tumorigenesis. | genetic transformation of plants by agrobacterium tumefaciens is mediated by a virulence (vir)-specific type iv secretion apparatus assembled from 11 virb proteins and vird4. virb1, targeted to the periplasm by an n-terminal signal peptide, is processed to yield virb1*, comprising the c-terminal 73 amino acids. the n-terminal segment, which shares homology with chicken egg white lysozyme as well as lytic transglycosylases, may provide local lysis of the peptidoglycan cell wall to create channels ... | 2000 | 10852875 |
| the brucella abortus ccrm dna methyltransferase is essential for viability, and its overexpression attenuates intracellular replication in murine macrophages. | the ccrm dna methyltransferase of the alpha-proteobacteria catalyzes the methylation of the adenine in the sequence gantc. like dam in the enterobacteria, ccrm plays a regulatory role in caulobacter crescentus and rhizobium meliloti. ccrm is essential for viability in both of these organisms, and we show here that it is also essential in brucella abortus. further, increased copy number of the ccrm gene results in striking changes in b. abortus morphology, dna replication, and growth in murine ma ... | 2000 | 10852881 |
| 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 |
| megaplasmid prme2011a of sinorhizobium meliloti is not required for viability. | we report the curing of the 1,360-kb megaplasmid prme2011a from sinorhizobium meliloti strain rm2011. with a positive selection strategy that utilized tn5b12-s containing the sacb gene, we were able to cure this replicon by successive rounds of selecting for deletion formation in vivo. subsequent southern blot, eckhardt gel, and pulsed-field gel electrophoresis analyses were consistent with the hypothesis that the resultant strain was indeed missing prme2011a. the cured derivative grew as well a ... | 2000 | 10852892 |
| sterol methyltransferase 1 controls the level of cholesterol in plants. | the side chain in plant sterols can have either a methyl or ethyl addition at carbon 24 that is absent in cholesterol. the ethyl addition is the product of two sequential methyl additions. arabidopsis contains three genes-sterol methyltransferase 1 (smt1), smt2, and smt3-homologous to yeast erg6, which is known to encode an s-adenosylmethionine-dependent c-24 smt that catalyzes a single methyl addition. the smt1 polypeptide is the most similar of these arabidopsis homologs to yeast erg6p. moreov ... | 2000 | 10852933 |
| repression of shoot growth, a bzip transcriptional activator, regulates cell elongation by controlling the level of gibberellins. | cell expansion, a developmental process regulated by both endogenous programs and environmental stimuli, is critically important for plant growth. here, we report the isolation and characterization of rsg (for repression of shoot growth), a transcriptional activator with a basic leucine zipper (bzip) domain. to examine the role of rsg in plant development, we generated transgenic tobacco plants expressing a dominant-negative form of rsg, which repressed the activity of full-length rsg. in transg ... | 2000 | 10852936 |
| reduced levels of chloroplast ftsh protein in tobacco mosaic virus-infected tobacco leaves accelerate the hypersensitive reaction. | in tobacco cultivars resistant to tobacco mosaic virus (tmv), infection results in the death of the infected cells accompanying the formation of necrotic lesions. to identify the genes involved in this hypersensitive reaction, we isolated the cdna of tobacco ds9, the transcript of which decreases before the appearance of necrotic lesions. the ds9 gene encodes a chloroplastic homolog of bacterial ftsh protein, which serves to maintain quality control of some cytoplasmic and membrane proteins. a l ... | 2000 | 10852937 |
| transferred dna (t-dna)-associated proteins of agrobacterium tumefaciens are exported independently of virb. | the transfer of t-dna from agrobacterium to plant cells is mediated by a system which involves the virb operon of the ti plasmid. we report that vire2 and vird2, two t-dna-associated proteins, as well as virf, a protein known to be secreted into plant cells, are present in the periplasm and supernatant fractions of growing cells of agrobacterium as are virj and chve, two known periplasmic proteins. two cytoplasmic proteins, ros and chloramphenicol acetyl transferase, and a vire2green fluorescent ... | 2000 | 10852952 |
| expression of full-length bioactive antimicrobial human lactoferrin in potato plants. | a cdna fragment encoding human lactoferrin (hlf) linked to a plant microsomal retention signal peptide (sek-del) was stably integrated into the solanum tuberosum genome by agrobacterium tumefaciens-mediated leaf disk transformation methods. the lactoferrin gene was expressed under control of both the auxin-inducible manopine synthase (mas) p2 promoter and the cauliflower mosaic virus (camv) 35s tandem promoter. the presence of the hlf cdna in the genome of regenerated transformed potato plants w ... | 2000 | 10853271 |
| a single amino acid substitution beyond the c2h2-zinc finger in ros derepresses virulence and t-dna genes in agrobacterium tumefaciens. | ros is a chromosomally-encoded repressor containing a novel c2h2 zinc finger in agrobacterium tumefaciens. ros regulates the expression of six virulence genes and an oncogene on the ti plasmid. constitutive expression of these genes occurs in the spontaneous mutant 4011r derived from the octopine strain ach-5, resulting in t-dna processing in the absence of induction, and in the biosynthesis of cytokinin. interestingly, the mutation in 4011r is an arg to cys conversion at amino acid residue 125 ... | 2000 | 10856653 |
| identification and subcellular localization of the legionella pneumophila icmx protein: a factor essential for establishment of a replicative organelle in eukaryotic host cells. | the gram-negative respiratory pathogen legionella pneumophila infects and grows within mammalian macrophages and protozoan host cells. upon uptake into macrophages, l. pneumophila establishes a replicative organelle that avoids fusion with endocytic vesicles. there are 24 dot/icm genes on the l. pneumophila chromosome required for biogenesis of this vacuole. many of the dot/icm proteins are predicted to be components of a membrane-bound secretion apparatus similar to type iv conjugal transfer sy ... | 2000 | 10858211 |
| importance of holotoxin assembly in ptl-mediated secretion of pertussis toxin from bordetella pertussis. | we examined the structural components of pertussis toxin that are required for efficient export from bordetella pertussis via the ptl system, a member of the type iv family of macromolecular transporters. first, we constructed a strain of b. pertussis that contains a functional ptl system but does not produce pertussis toxin. plasmids which express either the s1 subunit or the b oligomer were then introduced into this strain. we found that the b oligomer of the toxin is not secreted in the absen ... | 2000 | 10858221 |
| identification of genes required for chronic persistence of brucella abortus in mice. | the genetic basis for chronic persistence of brucella abortus in lymphoid organs of mice, cows, and humans is currently unknown. we identified b. abortus genes involved in chronic infection, by assessing the ability of 178 signature-tagged mutants to establish and maintain persistent infection in mice. each mutant was screened for its ability to colonize the spleens of mice at 2 and 8 weeks after inoculation. comparison of the results from both time points identified two groups of mutants attenu ... | 2000 | 10858227 |
| a critical role of sterols in embryonic patterning and meristem programming revealed by the fackel mutants of arabidopsis thaliana. | here we report a novel arabidopsis dwarf mutant, fackel-j79, whose adult morphology resembles that of brassinosteroid-deficient mutants but also displays distorted embryos, supernumerary cotyledons, multiple shoot meristems, and stunted roots. we cloned the fackel gene and found that it encodes a protein with sequence similarity to both the human sterol reductase family and yeast c-14 sterol reductase and is preferentially expressed in actively growing cells. biochemical analysis indicates that ... | 2000 | 10859167 |
| cambial-region-specific expression of the agrobacterium iaa genes in transgenic aspen visualized by a linked uida reporter gene. | the level of indole-3-acetic acid (iaa) was locally modified in cambial tissues of transgenic aspen (populus tremula l. x populus tremuloides michx.). we also demonstrate the use of a linked reporter gene to visualize the expression of the iaa genes. the rate-limiting bacterial iaa-biosynthetic gene iaam and the reporter gene for beta-glucuronidase (gus), uida, were each fused to the cambial-region-specific agrobacterium rhizogenes rolc promoter and linked on the same t-dna. in situ hybridizatio ... | 2000 | 10859183 |
| determination of transgene repeat formation and promoter methylation in transgenic plants. | the integration of transgenes into a plant host genome following agrobacterium tumefaciens-mediated or direct transformation may occur as a single copy or in the form of tandem repeats. the latter has been associated with promoter methylation and silencing of transgenes. thus, the early screening of such transgenic plants is desirable for ruling out future repeat-dependent transgene instability. we developed a simple pcr-based method in which primer pairs were specifically designed so that ampli ... | 2000 | 10868278 |
| the bases of crown gall tumorigenesis. | | 2000 | 10869063 |
| genome structure of the genus azospirillum. | azospirillum species are plant-associated diazotrophs of the alpha subclass of proteobacteria. the genomes of five of the six azospirillum species were analyzed by pulsed-field gel electrophoresis. all strains possessed several megareplicons, some probably linear, and 16s ribosomal dna hybridization indicated multiple chromosomes in genomes ranging in size from 4.8 to 9.7 mbp. the nifhdk operon was identified in the largest replicon. | 2000 | 10869094 |
| the plant vacuolar sorting receptor atelp is involved in transport of nh(2)-terminal propeptide-containing vacuolar proteins in arabidopsis thaliana. | many soluble plant vacuolar proteins are sorted away from secreted proteins into small vesicles at the trans-golgi network by transmembrane cargo receptors. cleavable vacuolar sorting signals include the nh(2)-terminal propeptide (ntpp) present in sweet potato sporamin (spo) and the cooh-terminal propeptide (ctpp) present in barley lectin (bl). these two proteins have been found to be transported by different mechanisms to the vacuole. we examined the ability of the vacuolar cargo receptor atelp ... | 2000 | 10871276 |
| 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 |
| biocontrol of the sugarcane borer eldana saccharina by expression of the bacillus thuringiensis cry1ac7 and serratia marcescens chia genes in sugarcane-associated bacteria. | the cry1ac7 gene of bacillus thuringiensis strain 234, showing activity against the sugarcane borer eldana saccharina, was cloned under the control of the tac promoter. the fusion was introduced into the broad-host-range plasmid pkt240 and the integration vector pjff350 and without the tac promoter into the broad-host-range plasmids pml122 and pkmm0. these plasmids were introduced into a pseudomonas fluorescens strain isolated from the phylloplane of sugarcane and the endophytic bacterium herbas ... | 2000 | 10877771 |
| isolation and characterization of 2,3-dichloro-1-propanol-degrading rhizobia. | 2,3-dichloro-1-propanol is more chemically stable than its isomer, 1, 3-dichloro-2-propanol, and is therefore more difficult to degrade. the isolation of bacteria capable of complete mineralization of 2, 3-dichloro-1-propanol was successful only from enrichments at high ph. the bacteria thus isolated were found to be members of the alpha division of the proteobacteria in the rhizobium subdivision, most likely agrobacterium sp. they could utilize both dihaloalcohol substrates and 2-chloropropioni ... | 2000 | 10877782 |
| molecular and ecological evidence for species specificity and coevolution in a group of marine algal-bacterial symbioses. | the phylogenetic relationships of bacterial symbionts from three gall-bearing species in the marine red algal genus prionitis (rhodophyta) were inferred from 16s rdna sequence analysis and compared to host phylogeny also inferred from sequence comparisons (nuclear ribosomal internal-transcribed-spacer region). gall formation has been described previously on two species of prionitis, p. lanceolata (from central california) and p. decipiens (from peru). this investigation reports gall formation on ... | 2000 | 10877801 |
| fluorescent whole-cell hybridization with 16s rrna-targeted oligonucleotide probes to identify brucella spp. by flow cytometry. | a whole-cell hybridization assay with fluorescent oligonucleotide probes derived from the 16s rrna sequence of brucella abortus in combination with flow cytometry has been developed. with the three fluorescent probes selected, a positive signal was observed with all the representative strains of the species and biovars of brucella and with a total of nine different brucella clinical isolates. using the b9 probe in the hybridization assay, it was possible to discriminate between brucella suis bio ... | 2000 | 10878084 |
| osmotic regulation of cyclic 1,2-beta-glucan synthesis. | in contrast to what happens in agrobacterium: tumefaciens and rhizobium: meliloti, synthesis of periplasmic cyclic 1,2-beta-glucan in brucella: spp. was not inhibited when bacteria were grown in media of high osmolarity. studies performed with crude membrane preparations showed that cyclic 1,2-beta-glucan synthetase of brucella: spp. was not inhibited by 0.5 m kcl or potassium glutamate; concentrations that completely inhibit the osmosensitive enzymes of a. tumefaciens a348 or r. meliloti 102f34 ... | 2000 | 10878137 |
| identification and cell cycle control of a novel pilus system in caulobacter crescentus. | pilus assembly in caulobacter: crescentus occurs during a short period of the cell cycle and pili are only present at the flagellar pole of the swarmer cell. here we report a novel assay to visualize pili by light microscopy that led to the purification of caulobacter: pili and the isolation of a cluster of seven genes, including the major pilin subunit gene pila. this gene cluster encodes a novel group of pilus assembly proteins. we have shown that the pila promoter is activated late in the cel ... | 2000 | 10880436 |
| the gene encoding the 17-kda antigen of bartonella henselae is located within a cluster of genes homologous to the virb virulence operon. | a bartonella henselae genomic a library was screened with antiserum generated in mice against live b. henselae. one of the immunoreactive clones expressed a 17-kda antigen that was characterized previously as an immunodominant protein of b. henselae. sequence analysis of the recombinant clone, pbhim-2, revealed that the open reading frame (orf) encoding the 17-kda antigen was situated between homologs of virb4 and virb6, two genes that belong to the virb operon. the virb operon has been associat ... | 2000 | 10882236 |
| genetically modified crops: methodology, benefits, regulation and public concerns. | the genetic modification of crop plants from the methodology involved in their production through to the current debate on their use in agriculture are reviewed. techniques for plant transformation by agrobacterium tumefaciens and particle bombardment, and for the selection of transgenic plants using marker genes are described. the benefits of currently available genetically modified (gm) crops in reducing waste and agrochemical use in agriculture, and the potential of the technology for further ... | 2000 | 10885105 |
| cell-specific and conditional expression of caffeoyl-coenzyme a-3-o-methyltransferase in poplar. | caffeoyl coenzyme a-3-o-methyltransferase (ccoaomt) plays an important role in lignin biosynthesis and is encoded by two genes in poplar (populus trichocarpa). here, we describe the expression pattern conferred by the two ccoaomt promoters when fused to the gus-coding sequence in transgenic poplar (populus tremula x populus alba). both genes were expressed similarly in xylem and differentially in phloem. in xylem, expression was preferentially observed in vessels and contact rays, whereas expres ... | 2000 | 10889235 |
| 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 |
| identification of phloem involved in assimilate loading in leaves by the activity of the galactinol synthase promoter. | the definition of "minor" veins in leaves is arbitrary and of uncertain biological significance. generally, the term refers to the smallest vein classes in the leaf, believed to function in phloem loading. we found that a galactinol synthase promoter, cloned from melon (cucumis melo), directs expression of the gusa gene to the smallest veins of mature arabidopsis and cultivated tobacco (nicotiana tabacum) leaves. this expression pattern is consistent with the role of galactinol synthase in sugar ... | 2000 | 10889241 |
| isolation and characterization of plant n-acetyl glucosaminyltransferase i (gnti) cdna sequences. functional analyses in the arabidopsis cgl mutant and in antisense plants. | we report on the isolation and characterization of full-length cdna sequences coding for n-acetylglucosaminyltransferase i (gnti) from potato (solanum tuberosum l.), tobacco (nicotiana tabacum l.), and arabidopsis. the deduced polypeptide sequences show highest homology among the solanaceous species (93% identity between potato and tobacco compared with about 75% with arabidopsis) but share only weak homology with human gnti (35% identity). in contrast to the corresponding enzymes from animals, ... | 2000 | 10889259 |
| molecular genetic characterization and subcellular localization of theileria annulata mitochondrial heat-shock protein 70. | a theileria annulata mitochondrial heat-shock protein of the 70-kda family (tamthsp70) was isolated by screening of the cdna library of a t. annulata-infected bovine lymphoblastoid cell line with an antibody raised against t. annulata schizonts. the tamthsp70 coding sequence was found to be most closely related to a previously reported mitochondrial hsp70 gene of eimeria tenella exhibiting a similarity of 67% with mitochondrial hsp70 genes of eukaryotic plants (pisum sativum, phaseolus vulgaris) ... | 2000 | 10894469 |
| self-assembly of the agrobacterium tumefaciens virb11 traffic atpase. | the agrobacterium tumefaciens virb11 atpase is a component of a type iv transporter dedicated to t-dna delivery to plant cells. in this study, we tested a prediction from genetic findings that virb11 self-associates in vivo. a chimeric protein composed of virb11 fused to the dna binding domain of lambda ci repressor protein formed dimers, as shown by immunity of escherichia coli to lambda superinfection. an allele encoding virb11 fused at its c terminus to the green fluorescent protein (gfp) exe ... | 2000 | 10894719 |
| transcriptional analysis of major heat shock genes of helicobacter pylori. | the transcriptional organization and heat inducibility of the major heat shock genes hrca, dnak, dnaj, groel, and htpg were analyzed on the transcriptional level in helicobacter pylori strain 69a. the strongly heat-induced dnak operon was found to be tricistronic, consisting of the genes hrca, grpe, and dnak. the dnaj gene specified one monocistronic mrna which was also heat inducible. the genes groes and groel were transcribed as one strongly heat-inducible bicistronic mrna which exhibited exac ... | 2000 | 10894735 |
| involvement of a plasmid in virulence of campylobacter jejuni 81-176. | campylobacter jejuni strain 81-176 contains two, previously undescribed plasmids, each of which is approximately 35 kb in size. although one of the plasmids, termed ptet, carries a teto gene, conjugative transfer of tetracycline resistance to another strain of c. jejuni could not be demonstrated. partial sequence analysis of the second plasmid, pvir, revealed the presence of four open reading frames which encode proteins with significant sequence similarity to helicobacter pylori proteins, inclu ... | 2000 | 10899834 |
| korrigan, an arabidopsis endo-1,4-beta-glucanase, localizes to the cell plate by polarized targeting and is essential for cytokinesis. | the formation of the cell plate, a unique structure in dividing plant cells, is pivotal for cytokinesis. a mutation in the arabidopsis korrigan (kor) gene causes the formation of aberrant cell plates, incomplete cell walls, and multinucleated cells, leading to severely abnormal seedling morphology. the mutant, designed kor1-2, was identified as a stronger allele than the previously identified kor1-1, which appears to be defective only in cell elongation. kor1 encodes an endo-1,4-beta-d-glucanase ... | 2000 | 10899980 |
| the c-terminal dilysine motif confers endoplasmic reticulum localization to type i membrane proteins in plants. | the tomato cf-9 disease resistance gene encodes a type i membrane protein carrying a cytosolic dilysine motif. in mammals and yeast, this motif promotes the retrieval of type i membrane proteins from the golgi apparatus to the endoplasmic reticulum (er). to test whether the c-terminal kkxx signal of cf-9 is functional as a retrieval motif and to investigate its role in plants, green fluorescent protein (gfp) was fused to the transmembrane domain of cf-9 and expressed in yeast, arabidopsis, and t ... | 2000 | 10899983 |
| sustained but not transient phytochrome a signaling targets a region of an lhcb1*2 promoter not necessary for phytochrome b action. | current evidence is inconclusive regarding the point of signaling convergence downstream from different members of the phytochrome family. in transgenic arabidopsis, the activity of a reporter enzyme under the control of the -453 to +67 fragment of an lhcb1*2 promoter shows very low fluence responses (vlfrs) and high-irradiance responses (hirs) mediated by phytochrome a and low-fluence responses (lfrs) mediated by phytochrome b. a 5' deletion of the promoter to -134 abolished the hir without aff ... | 2000 | 10899984 |
| 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 |
| transcription of the nfra-ywch operon from bacillus subtilis is specifically induced in response to heat. | the nfra protein, an oxidoreductase from the soil bacterium bacillus subtilis, is synthesized during the stationary phase and in response to heat. analysis of promoter mutants revealed that the nfra gene belongs to the class iii heat shock genes in b. subtilis. an approximate 10-fold induction at both the transcriptional and the translational levels was found after thermal upshock. this induction resulted from enhanced synthesis of mrna. genetic and northern blot analyses revealed that nfra and ... | 2000 | 10913069 |
| characterization of lrpc dna-binding properties and regulation of bacillus subtilis lrpc gene expression. | the lrpc gene was identified during the bacillus subtilis genome sequencing project. previous experiments suggested that lrpc has a role in sporulation and in the regulation of amino acid metabolism and that it shares features with escherichia coli lrp, a transcription regulator (c. beloin, s. ayora, r. exley, l. hirschbein, n. ogasawara, y. kasahara, j. c. alonso, and f. le hégarat, mol. gen. genet. 256:63-71, 1997). to characterize the interactions of lrpc with dna, the protein was overproduce ... | 2000 | 10913073 |
| virb6 is required for stabilization of virb5 and virb3 and formation of virb7 homodimers in agrobacterium tumefaciens. | virb6 from agrobacterium tumefaciens is an essential component of the type iv secretion machinery for t pilus formation and genetic transformation of plants. due to its predicted topology as a polytopic inner membrane protein, it was proposed to form the transport pore for cell-to-cell transfer of genetic material and proteinaceous virulence factors. here, we show that the absence of virb6 leads to reduced cellular levels of virb5 and virb3, which were proposed to assist t pilus formation as min ... | 2000 | 10913084 |
| characterization of s-triazine herbicide metabolism by a nocardioides sp. isolated from agricultural soils. | atrazine, a herbicide widely used in corn production, is a frequently detected groundwater contaminant. nine gram-positive bacterial strains able to use this herbicide as a sole source of nitrogen were isolated from four farms in central canada. the strains were divided into two groups based on repetitive extragenic palindromic (rep)-pcr genomic fingerprinting with eric and boxa1r primers. based on 16s ribosomal dna sequence analysis, both groups were identified as nocardioides sp. strains. none ... | 2000 | 10919761 |
| 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 |
| 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 |
| knockout of the p-coumarate decarboxylase gene from lactobacillus plantarum reveals the existence of two other inducible enzymatic activities involved in phenolic acid metabolism. | lactobacillus plantarum nc8 contains a pdc gene coding for p-coumaric acid decarboxylase activity (pdc). a food grade mutant, designated lpd1, in which the chromosomal pdc gene was replaced with the deleted pdc gene copy, was obtained by a two-step homologous recombination process using an unstable replicative vector. the lpd1 mutant strain remained able to weakly metabolize p-coumaric and ferulic acids into vinyl derivatives or into substituted phenyl propionic acids. we have shown that l. plan ... | 2000 | 10919793 |
| 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 |
| lipopolysaccharides of rhizobium etli strain g12 act in potato roots as an inducing agent of systemic resistance to infection by the cyst nematode globodera pallida. | recent studies have shown that living and heat-killed cells of the rhizobacterium rhizobium etli strain g12 induce in potato roots systemic resistance to infection by the potato cyst nematode globodera pallida. to better understand the mechanisms of induced resistance, we focused on identifying the inducing agent. since heat-stable bacterial surface carbohydrates such as exopolysaccharides (eps) and lipopolysaccharides (lps) are essential for recognition in the symbiotic interaction between rhiz ... | 2000 | 10919815 |
| effect of field inoculation with sinorhizobium meliloti l33 on the composition of bacterial communities in rhizospheres of a target plant (medicago sativa) and a non-target plant (chenopodium album)-linking of 16s rrna gene-based single-strand conformation polymorphism community profiles to the diversity of cultivated bacteria. | fourteen weeks after field release of luciferase gene-tagged sinorhizobium meliloti l33 in field plots seeded with medicago sativa, we found that the inoculant also occurred in bulk soil from noninoculated control plots. in rhizospheres of m. sativa plants, s. meliloti l33 could be detected in noninoculated plots 12 weeks after inoculation, indicating that growth in the rhizosphere preceded spread into bulk soil. to determine whether inoculation affected bacterial diversity, 1,119 bacteria were ... | 2000 | 10919821 |
| pcr use of highly conserved dna regions for identification of sinorhizobium meliloti. | a pcr identification method in which four primers that recognize homologous conserved regions in the sinorhizobium meliloti genome are used was developed and tested. the regions used for identification were the nodbox 4 locus, which is located in one of the symbiotic megaplasmids, and the mucr gene, which is located in the chromosome. the new method was used to establish a collection of s. meliloti strains from polluted soils. | 2000 | 10919829 |
| bacterial type iv secretion: conjugation systems adapted to deliver effector molecules to host cells. | several bacterial pathogens utilize conjugation machines to export effector molecules during infection. such systems are members of the type iv or 'adapted conjugation' secretion family. the prototypical type iv system is the agrobacterium tumefaciens t-dna transfer machine, which delivers oncogenic nucleoprotein particles to plant cells. other pathogens, including bordetella pertussis, legionella pneumophila, brucellaspp. and helicobacter pylori, use type iv machines to export effector proteins ... | 2000 | 10920394 |
| the t-pilus of agrobacterium tumefaciens. | t-pilus biogenesis uses a conserved transmembrane nucleoprotein- and protein-transport apparatus for the transport of cyclic t-pilin subunits to the agrobacterium cell surface. t-pilin subunits are processed from full-length virb2 pro-pilin into a cyclized peptide, a rapid reaction that is agrobacterium specific and can occur in the absence of ti-plasmid genes. | 2000 | 10920395 |
| characterization of bartonella clarridgeiae flagellin (flaa) and detection of antiflagellin antibodies in patients with lymphadenopathy. | cat scratch disease (csd) is a frequent clinical outcome of bartonella henselae infection in humans. recently, two case reports indicated bartonella clarridgeiae as an additional causative agent of csd. both pathogens have been isolated from domestic cats, which are considered to be their natural reservoir. b. clarridgeiae and b. henselae can be distinguished phenotypically by the presence or absence of flagella, respectively. separation of the protein content of purified flagella of b. clarridg ... | 2000 | 10921956 |
| 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 |
| purification and characterization of a novel lactonohydrolase from agrobacterium tumefaciens. | a novel lactonohydrolase, catalyzing the stereospecific hydrolysis of l-pantoyl lactone to l-pantoic acid, was purified 2,400-fold to apparent homogeneity with a 1.96% overall recovery from agrobacterium tumefaciens aku 316 through a purification procedure including ammonium sulfate fractionation, and column chromatographies on deae-sephacel, phenyl-sepharose cl-4b, sephacryl s-200, mono-q and alkyl-superose. the relative molecular mass of the native enzyme estimated on high-pressure gel permeat ... | 2000 | 10923798 |
| the maternal chromosome set is the target of the t-dna in the in planta transformation of arabidopsis thaliana. | in planta transformation methods are now commonly used to transform arabidopsis thaliana by agrobacterium tumefaciens. the origin of transformants obtained by these methods has been studied by inoculating different floral stages and examining gametophytic expression of an introduced beta-glucuronidase marker gene encoding gus. we observed that transformation can still occur after treating flowers where embryo sacs have reached the stage of the third division. no gus expression was observed in em ... | 2000 | 10924482 |
| the transfer of dna from agrobacterium tumefaciens into plants: a feast of fundamental insights. | | 2000 | 10929098 |
| enhanced attachment of bradyrhizobium japonicum to soybean through reduced root colonization of internally seedborne microorganisms. | internally seedborne microorganisms are those surviving common surface sterilization procedures. such microbes often colonize the radicle surface of a germinating soybean (glycine max) seed, introducing an undefined parameter into studies on attachment and infection by bradyrhizobium japonicum. bacterial isolates from surface-sterilized soybean seed, cv. williams 82 and cv. maverick, used in our studies, were identified as agrobacterium radiobacter, aeromonas sp., bacillus spp., chryseomonas lut ... | 2000 | 10932352 |
| mm1, a temperate bacteriophage of the type 23f spanish/usa multiresistant epidemic clone of streptococcus pneumoniae: structural analysis of the site-specific integration system. | we have characterized a temperate phage (mm1) from a clinical isolate of the multiply antibiotic-resistant spanish/american 23f streptococcus pneumoniae clone (spain(23f)-1 strain). the 40-kb double-stranded genome of mm1 has been isolated as a dna-protein complex. the use of mm1 dna as a probe revealed that the phage genome is integrated in the host chromosome. the host and phage attachment sites, attb and attp, respectively, have been determined. nucleotide sequencing of the attachment sites i ... | 2000 | 10933687 |
| production of d-amino acid using whole cells of recombinant escherichia coli with separately and coexpressed d-hydantoinase and n-carbamoylase. | we developed a fully enzymatic process employing d-hydantoinase and n-carbamoylase for the production of d-amino acid from 5'-monosubstituted hydantoin. for the comparison of the reaction systems using two sequential enzymes, d-hydantoinase of bacillus stearothermophilus sd1 and n-carbamoyl-d-amino acid amidohydrolase (n-carbamoylase) of agrobacterium tumefaciens nrrl b11291 were separately expressed in each host cell and coexpressed in the same host cell. a high level and constitutive expressio ... | 2000 | 10933829 |