| lysogeny and bacteriocinogeny in xenorhabdus nematophilus and other xenorhabdus spp. | induction by mitomycin or high-temperature treatment resulted in the production of bacteriocins and phages in both phases of xenorhabdus nematophilus a24, indicating lysogeny. phage dna purified from x. nematophilus a24 hybridized to several fragments of drai-digested a24 chromosomal dna, confirming that the phage genome was incorporated into the bacterial chromosome. bacteriocins and phages were detected in cultures of most other xenorhabdus spp. after mitomycin or high-temperature treatment. x ... | 1992 | 1444417 |
| fatty acid-enhanced binding of flavin mononucleotide to bacterial luciferase measured by steady-state fluorescence. | bacterial luciferase catalyzes the oxidation of reduced flavin mononucleotide and tetradecanal resulting in the emission of light. we have investigated the interactions of a recombinant luciferase from a terrestrial bacterium xenorhabdus luminescens with the reaction products, fmn and myristic acid, using steady-state fluorescence spectroscopy. quenching of the intrinsic fluorescence and fmn fluorescence on binding of fmn to luciferase was found to be greatly stimulated in the presence of myrist ... | 1992 | 1445293 |
| plasmids and phase variation in xenorhabdus spp. | three strains of xenorhabdus nematophilus (a24, f1, nc116) and strain dan of xenorhabdus bovienii were tested to evaluate whether the phase variation observed in these bacteria was in any way connected with plasmids. the plasmid patterns of both phases of a24 and f1 strains were the same, whereas the two nc116 phases had only one band each. no difference was observed between the undigested or digested plasmid patterns of the two phases from the three strains. no plasmid was detected in either ph ... | 1991 | 1768133 |
| biologically active metabolites from xenorhabdus spp., part 2. benzopyran-1-one derivatives with gastroprotective activity. | two novel antibiotic compounds, named xenocoumacins 1 [2] and 2 [3], with potent antiulcer activity were isolated from cultures of xenorhabdus spp. both compounds exhibit antibacterial activity and potent antiulcer activity against stress-induced ulcers when dosed orally. in addition, 2 has antifungal activity. their chemical structures were determined by extensive 1h-nmr, 13c-nmr, and mass spectral studies to be 3,4-dihydro-8-hydroxy-1h-2-benzopyran-1-one derivatives. | 1991 | 1955881 |
| transformation of xenorhabdus nematophilus. | the ability of xenorhabdus nematophilus 19061/1 to be transformed by phk17 plasmid dna was studied and optimized. a number of factors, including culture conditions, stage of growth, transformation buffer ph, cation type and concentration required for the production of competency, washing, heat shock conditions, and cell-dna ratio, were found to affect transformation significantly. on the basis of these observations, a procedure for the routine transformation of x. nematophilus 19061/1 at frequen ... | 1989 | 2729982 |
| xenorhabdus luminescens (dna hybridization group 5) from human clinical specimens. | an unusual isolate from a human leg wound was identified as xenorhabdus luminescens. this finding led to the discovery or isolation of four additional strains, two from blood and two from wounds. three of the five strains were from patients in san antonio, tex. three strains were studied by dna-dna hybridization (s1 nuclease-trichloroacetic acid method) and were 77 to 100% related to each other, 34% related to the type strain of x. luminescens, 35 to 40% related to three of grimont's other dna h ... | 1989 | 2768446 |
| identification of an anthraquinone pigment and a hydroxystilbene antibiotic from xenorhabdus luminescens. | the entomopathogenic bacterium xenorhabdus luminescens produces a red pigment and an antibiotic in insect carcasses in which it grows and in axenic cultures. the pigment was purified and identified as the anthraquinone derivative 1,6-dihydroxy-4-methoxy-9,10-anthraquinone, which exhibits a ph-sensitive color change, i.e., it is yellow below ph 9 and red above ph 9. the antibiotic was also purified and identified as the hydroxystilbene derivative 3,5-dihydroxy-4-isopropylstilbene. | 1988 | 3415225 |
| protein inclusions produced by the entomopathogenic bacterium xenorhabdus nematophilus subsp. nematophilus. | the entomopathogenic bacterium xenorhabdus nematophilus subsp. nematophilus produces two types of intracellular inclusion bodies during in vitro culture. large cigar-shaped inclusions (designated type 1) and smaller ovoid inclusions (designated type 2) were purified from cell lysates, using differential centrifugation in discontinuous glycerol gradients and isopycnic density gradient centrifugation in sodium diatrizoate. the inclusions, composed almost exclusively of protein, are readily soluble ... | 1987 | 3667532 |
| antimicrobial activity and biosynthesis of indole antibiotics produced by xenorhabdus nematophilus. | we have investigated the mechanism of action and physiology of production of the indole derivative antibiotics produced by the nematode-associated, entomopathogenic bacterium xenorhabdus nematophilus. maximum antibiotic concentration was reached during the late stationary phase of growth, and the antibiotic yield was appreciably enhanced by supplementation with tryptophan. antibiotic biosynthesis apparently involved the removal of the side-chain carboxyl (c-1) carbon of tryptophan. the c-3 methy ... | 1993 | 7510325 |
| tryptophan 250 on the alpha subunit plays an important role in flavin and aldehyde binding to bacterial luciferase. effects of w-->y mutations on catalytic function. | bacterial luciferase is a heterodimer (alpha beta) that catalyzes the oxidation of fmnh2 and a fatty aldehyde, resulting in light emission. to explore the nature of the flavin binding site with respect to the role of tryptophan residues, the catalytic and binding properties of single-point mutants of xenorhabdus luminescens luciferase with one of the eight tryptophans converted to a tyrosine residue were investigated by luminescence and fluorescence measurements. conversion of tryptophans 194 an ... | 1995 | 7578121 |
| purification and characterization of xenorhabdicin, a phage tail-like bacteriocin, from the lysogenic strain f1 of xenorhabdus nematophilus. | xenorhabdicin, the phage tail-like bacteriocins of xenorhabdus nematophilus, and phage head particles, elements produced together after mitomycin induction in x. nematophilus lysogenic strain f1 cultures, were separated by deae chromatography, examined by transmission electron microscopy, and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. electrophoresis of xenorhabdicin showed two major subunits of 43 and 20 kda corresponding to the sheath and the inner core, respec ... | 1995 | 7646048 |
| characterization and environmental regulation of outer membrane proteins in xenorhabdus nematophilus. | we have examined the production of the outer membrane proteins of the primary and secondary forms of xenorhabdus nematophilus during exponential- and stationary-phase growth at different temperatures. the most highly expressed outer membrane protein of x. nematophilus was opnp. the amino acid composition of opnp was very similar to those of the porin proteins ompf and ompc of escherichia coli. n-terminal amino acid sequence analysis revealed that residues 1 to 27 of the mature opnp shared 70 and ... | 1995 | 7887602 |
| expression of luxcd-e in anabaena sp. can replace the use of exogenous aldehyde for in vivo localization of transcription by luxab. | the genes luxcdabe from four luminescent bacteria suffice for light production in escherichia coli [meighen, microbiol. rev. 55 (1991) 123-142]. we have inserted these gene clusters between inverted polylinkers, and placed the resulting cassettes as reporters within derivatives of transposon tn5. anabaena sp. strain pcc 7120 was mutagenized with these transposons. the luminescence of all but the most highly self-luminescent resulting derivatives of anabaena sp. was strongly dependent on exogenou ... | 1994 | 7959046 |
| antimicrobial metabolites from a bacterial symbiont. | two types of antibiotics, namely, indoles and dithiolopyrrolones, have been isolated and identified from xenorhabdus bovienii a2. compounds 1 and 2 showed strong activity against cryptococcus neoformans, compounds 3 and 4 showed strong activity against botrytis cinerea, and compounds 1, 3, and 4 showed significant activity against phytophthora infestants (2 was not tested). in addition, two lower homologues of xenorhabdins 5 and 6, namely, 6-(n-3'-methylbutanamido)-4,5-dihydro-1,2-dithiolo[4,3-b ... | 1995 | 7561900 |
| interaction of mutants of xenorhabdus nematophilus (enterobacteriaceae) with antibacterial systems of galleria mellonella larvae (insecta: pyralidae). | xenorhabdus nematophilus mutants that took longer to kill insects than did the wild type were used to determine the relationship of the physicochemical properties and outer membrane composition to bacterial interaction with the antibacterial systems of galleria mellonella larvae and to bacterial virulence. insect serum slowed the growth of the wild-type and mutant bacteria. this was attributed to increased spheroplast formation for the mutants. spheroplast formation was associated with an increa ... | 1994 | 8012904 |
| inability of the polyphasic approach to systematics to determine the relatedness of the genera xenorhabdus and photorhabdus. | comparative analysis of the genes coding for 16s rrna of the type strains of xenorhabdus and photorhabdus species indicates the close phylogenetic relationship of these two genera. however, distance matrix analyses do not unambiguously separate the symbionts of entomopathogenic nematodes according to their assignment into different genera. when various 16s rrna gene sequences from a selection of members of the gamma subclass of proteobacteria and outgroup taxa were used, the intrageneric relatio ... | 1995 | 7537072 |
| heterologous gene expression in campylobacter coli: the use of bacterial luciferase in a promoter probe vector. | a novel promoter probe plasmid (psp73) was constructed to allow the analysis of environmentally regulated gene expression in campylobacter. the vector utilizes the luxab genes from xenorhabdus luminescens, which encode a thermostable luciferase, as reporters of gene expression. the utility of this reporter system was demonstrated by placing the expression of luxab under the transcriptional control of the flaa gene promoter. | 1993 | 8405932 |
| different dna-binding proteins in the primary and secondary forms of xenorhabdus luminescens. | basic, heat-stable proteins binding to double-stranded dna (hasp) were isolated from the primary and secondary forms of xenorhabdus luminescens and their composition compared. two of the proteins with low molecular weight are present in both the primary and secondary forms, whereas two others are present only in the latter. the described protein fractions may be involved in the regulation of transitions between the two forms of x. luminescens. | 1993 | 7504870 |
| antibiotic activity of xenorhabdus spp., bacteria symbiotically associated with insect pathogenic nematodes of the families heterorhabditidae and steinernematidae. | a wide range of micro-organisms, including yeasts, was found to be inhibited by the primary form of xenorhabdus spp., but not by the secondary form. only one xenorhabdus strain, the symbiont of neoaplectana glaseri, did not inhibit any of the micro-organisms tested; it is suggested that this strain may not have been isolated in the primary form. gram-positive bacteria were sensitive to all active isolates of xenorhabdus; each of the yeasts and almost all of the gram-negative bacteria were sensit ... | 1982 | 7183749 |
| neoaplectana species: specificity of association with bacteria of the genus xenorhabdus. | each of five neoaplectana (nematoda: steinernematidae) species was cultured monoxenically with various xenorhabdus (eubacteriales: enterobacteriaceae) isolates. the nematodes were usually able to reproduce when cultured with the bacterial symbiont of any one of the five neoaplectana spp. but never with xenorhabdus luminescens, symbiotic with heterorhabditis spp., or with the xenorhabdus sp. isolated from an undescribed steinernematid species. only neoaplectana bibionis could be cultured with the ... | 1983 | 6832284 |
| diversity of the phosphoenolpyruvate/glucose phosphotransferase system in the enterobacteriaceae. | the presence of the phosphoenolpyruvate glucose phosphotransferase entry routes was studied in 97 genospecies of enterobacteriaceae. phosphoenolpyruvate(pep)-dependent phosphorylation of alpha-methyl-d-glucoside and 2-deoxyglucose was evidenced in 72 species (group i organisms), suggesting the presence of both the iiglc (formerly ii-bglc/iiiglc) and iiman (formerly ii-b/ii-aman) entry routes. erwinia amylovora, budvicia aquatica and all species of leminorella and proteus (as defined by dna relat ... | 1987 | 3606872 |
| molecular analysis of the two-component genes, ompr and envz, in the symbiotic bacterium xenorhabdus nematophilus. | in escherichia coli the histidine kinase sensor protein, envz, undergoes autophosphorylation and subsequently phosphorylates the regulatory protein, ompr. modulation of the levels of ompr-phosphate controls the differential expression of ompf and ompc. while the phosphotransfer reaction between envz and ompr has been extensively studied, the domains involved in the sensing function of envz are not well understood. we have used a comparative approach to study the sensing function of envz. during ... | 1995 | 8801419 |
| a numerical taxonomic study of the genus xenorhabdus (enterobacteriaceae) and proposed elevation of the subspecies of x. nematophilus to species. | data from a study of both phases of 21 strains of xenorhabdus examined for 240 characters were subjected to numerical analysis. only 60 characters were used for the analyses, since 169 characters were common to all isolates, and the acidification data essentially duplicated the assimilation tests. the data were arranged in seven ways to determine the significance of characters affected by phase change and of weak responses. most of the analyses involved calculation of similarities by the jaccard ... | 1988 | 3246587 |
| functional and regulatory analysis of the ompf-like porin, opnp, of the symbiotic bacterium xenorhabdus nematophilus. | the function and novel regulation of opnp of the symbiotic/pathogenic bacterium, xenorhabdus nematophilus was studied. in vitro pore-function analysis of purified opnp indicated that the single-channel-conductance values were similar to that measured for the porin protein, ompf, of esherichia coli. nucleotide sequence analysis revealed that the mature opnp protein contained 348 amino acid residues and shared 55% amino acid sequence identity with ompf. similar to ompf, opnp mapped between asns an ... | 1995 | 8817498 |
| preliminary observations of a bacteriophage infecting xenorhabdus luminescens (enterobacteriaceae). | a bacteriophage infective to xenorhabdus luminescens, a bacterial symbiont of heterorhabditid nematodes, was recovered from insects that supported poor nematode development. plaque tests showed the phage particles to be infective only to primary and not secondary colonies of x. luminescens. the phage was not infective to x. nematophilus primaries or secondaries. the bacteriophage particles ranged 80-90 nm in length, with the head ranging from 40 to 50 nm in diameter. restriction analysis was per ... | 1989 | 2920806 |
| chitinase activity of xenorhabdus and photorhabdus species, bacterial associates of entomopathogenic nematodes. | xenorhabdus nematophilus (three strains), xenorhabdus bovienii (one strain), and photorhabdus luminescens (one strain) showed both exo- and endochitinase activity using p-nitrophenyl-n-acetyl-beta-d-glucosaminide and p-nitrophenyl-beta-d-n,n',n'-triacetylchitotriose, respectively, as substrates. one to three bands were detected on page gel with glycol chitin after electrophoresis. variation in exo- and endochitinase activity among different species and strains was detected with the strongest act ... | 1996 | 8858906 |
| effect of cucurbitacin d on in vitro growth of xenorhabdus and photorhabdus spp., symbiotic bacteria of entomopathogenic nematodes. | in vitro assays were conducted to determine the effect of cucurbitacin d, an oxygenated tetracyclic triterpenoid found in cucurbits, on the growth of xenorhabdus isolated from steinernema carpocapsae (all, mexican, agriotos strains), steinernema riobravis, steinernema glaseri (nc strain, strain 27), and photorhabdus from heterorhabditis bacteriophora (nc, lewiston strains), and heterorhabditis sp. (fl2122 strain). cucurbitacin d inhibited the growth of four isolates, had no effect on the growth ... | 1996 | 8858910 |
| bioluminescence of the insect pathogen xenorhabdus luminescens. | luminescence of batch cultures of xenorhabdus luminescens was maximal when cultures approached stationary phase; the onset of in vivo luminescence coincided with a burst of synthesis of bacterial luciferase, the enzyme responsible for luminescence. expression of luciferase was aldehyde limited at all stages of growth, although more so during the preinduction phase. luciferase was purified from cultures of x. luminescens hm to a specific activity of 4.6 x 10(13) guanta/s per mg of protein and fou ... | 1989 | 2604399 |
| growth and luminescence of the bacterium xenorhabdus luminescens from a human wound. | xenorhabdus luminescens, a newly isolated luminous bacterium collected from a human wound, was characterized. the effects of ionic strength, temperature, oxygen, and iron on growth and development of the bioluminescent system were studied. the bacteria grew and emitted light best at 33 degrees c in a medium with low salt, and the medium after growth of cells to a high density was found to have antibiotic activity. the emission spectrum peaked at 482 nm in vivo and at 490 nm in vitro. both growth ... | 1989 | 2604398 |
| phylogenetic relationships of entomopathogenic nematophilic bacteria: xenorhabdus spp. and photorhabdus sp. | phylogenetic relationships of xenorhabdus spp. and photorhabdus sp. were investigated on the basis of 16s rrna gene sequences. xenorhabdus spp. and photorhabdus sp. were grouped together with proteus vulgaris and arsenophonus nasoniae. this group was distant from other members of the family enterobacteriaceae. xenorhabdus japonicus, previously proposed as a new species, was nearly located to xenorhabdus nematophilus. signature nucleotides of x. japonicus were identified that distinguish it other ... | 1996 | 8914266 |
| the nucleotide sequence of the luxa and luxb genes of xenorhabdus luminescens hm and a comparison of the amino acid sequences of luciferases from four species of bioluminescent bacteria. | the luxa and luxb genes of bioluminescent bacteria encode the alpha and beta subunits of luciferase, respectively. sequences of the luxa and luxb genes of xenorhabdus luminescens, the only terrestrial bioluminescent bacterium known, were determined and the amino acid sequence of luciferase deduced. the alpha subunit was found to contain 360 amino acids and has a calculated molecular weight of 41,005 da, while the beta subunit contains 327 amino acids and has a calculated molecular weight of 37,6 ... | 1990 | 2383248 |
| cloning and nucleotide sequence of a flagellin encoding genetic locus from xenorhabdus nematophilus: phase variation leads to differential transcription of two flagellar genes (flicd). | the insect-pathogenic bacterium xenorhabdus undergoes spontaneous phase variation involving a large number of phenotypes. our previous study indicated that phase i variants were motile, whereas phase ii variants of x. nematophilus f1 were nonflagellated cells which did not synthesize flagellin [givaudan a., baghdiguian, s., lanois, a. and boemare, n. (1995) appl. environ. microbiol. 61, 1408-1413]. in order to approach the study of the flagellar switching, a locus containing two orfs from x. nem ... | 1996 | 8996114 |
| development and application of oligonucleotide probes for molecular identification of xenorhabdus species. | synthetic deoxyoligonucleotide probes that hybridized against the region at positions 455 through 480 of 16s rrna were developed for the identification of all five xenorhabdus species. sequence variation in the respective rrna region between two strains of xenorhabdus luminescens in addition allowed the construction of two strain-specific probes. of 27 isolates determined to be xenorhabdus strains by phenotypic characterization, 24 could be assigned to four of the five species. two strains (hl-1 ... | 1990 | 2310180 |
| role of the histidine kinase, envz, in the production of outer membrane proteins in the symbiotic-pathogenic bacterium xenorhabdus nematophilus. | we show that inactivation of envz, the gene encoding the histidine kinase sensor protein, envz, of xenorhabdus nematophilus, affected the production of several outer membrane proteins (opns). x. nematophilus produced five major opns during exponential growth. insertional inactivation of envz led to a decrease in the production of opnp, the ompf-like pore-forming protein which constitutes approximately 50% of the total outer membrane protein in x. nematophilus. opna production was also reduced, w ... | 1997 | 9055414 |
| the nucleotide sequence of the luxd gene of xenorhabdus luminescens hm. | | 1990 | 2216747 |
| cloning, organization, and expression of the bioluminescence genes of xenorhabdus luminescens. | the lux genes of xenorhabdus luminescens, a symbiont of the nematode heterorhabditis bacteriophora, were cloned and expressed in escherichia coli. the expression of these genes in e. coli was qualitatively similar to their expression in x. luminescens. the organization of the genes is similar to that found in the marine luminous bacteria. hybridization studies with the dna that codes for the two subunits of luciferase revealed considerable homology among all of the strains of x. luminescens and ... | 1990 | 2211511 |
| nucleotide sequence, expression, and properties of luciferase coded by lux genes from a terrestrial bacterium. | the lux genes required for expression of luminescence have been cloned from a terrestrial bacterium, xenorhabdus luminescens, and the nucleotide sequences of the luxa and luxb genes coding for the alpha and beta subunits of luciferase determined. the lux gene organization was closely related to that of marine bacteria from the vibrio genus with the luxd gene being located immediately upstream and the luxe downstream of the luciferase genes, luxab. a high degree of homology (85% identity) was fou ... | 1990 | 2204626 |
| cloning and nucleotide sequences of lux genes and characterization of luciferase of xenorhabdus luminescens from a human wound. | xenorhabdus luminescens hw is the only known luminous bacterium isolated from a human (wound) source. a recombinant plasmid was constructed that contained the x. luminescens hw luxa and luxb genes, encoding the luciferase alpha and beta subunits, respectively, as well as luxc, luxd, and a portion of luxe. the nucleotide sequences of these lux genes, organized in the order luxcdabe, were determined, and overexpression of the cloned luciferase genes was achieved in escherichia coli host cells. the ... | 1991 | 1995589 |
| biologically active metabolites from xenorhabdus spp., part 1. dithiolopyrrolone derivatives with antibiotic activity. | five related antibiotic compounds, named xenorhabdins, were isolated from cultures of xenorhabdus spp., bacteria symbiotically associated with insect-pathogenic nematodes. their chemical structures were elucidated by x-ray crystallography, nmr, and mass spectral analyses to be n-acyl derivatives of either 6-amino-4,5-dihydro-5-oxo-1,2-dithiolo [4,3-b] pyrrole (compounds 1-3) or 6-amino-4,5-dihydro-4-methyl-5-oxo-1,2-dithiolo[4,3-b] pyrrole (compounds 4 and 5). they are previously unreported memb ... | 1991 | 1955880 |
| a homoserine lactone autoinducer regulates virulence of an insect-pathogenic bacterium, xenorhabdus nematophilus (enterobacteriaceae). | n-beta-hydroxybutanoyl homoserine lactone (hbhl), the autoinducer of the luminescent system of vibrio harveyi, has been identified as the first small compound to restore virulence to avirulent mutants of xenorhabdus nematophilus. hbhl stimulated the level of lipase activity excreted by avirulent x. nematophilus and lowered the phenoloxidase activity in the hemolymph of insects infected with x. nematophilus, parameters that are both associated with insect pathogenesis. moreover, mortality of the ... | 1997 | 9286978 |
| nematophin, a novel antimicrobial substance produced by xenorhabdus nematophilus (enterobactereaceae). | a new antibiotic, nematophin, was isolated from strain bc1 of xenorhabdus nematophilus and detected in all strains of x. nematophilus studied. its structure is fully established as 3-indoleethyl (3'-methyl-2'-oxo)pentanamide by extensive spectroscopic study. the production of nematophin is affected by the strain type and culture conditions. the compound shows strong in vitro bioactivity against a series of fungal and bacterial species. | 1997 | 9304787 |
| development of species-specific hybridization probes for marine luminous bacteria by using in vitro dna amplification. | by using two highly conserved region of the luxa gene as primers, polymerase chain reaction amplification methods were used to prepare species-specific probes against the luciferase gene from four major groups of marine luminous bacteria. laboratory studies with test strains indicated that three of the four probes cross-reacted with themselves and with one or more of the other species at low stringencies but were specific for members of their own species at high stringencies. the fourth probe, g ... | 1991 | 1854194 |
| multiple repetitive elements and organization of the lux operons of luminescent terrestrial bacteria. | the complete nucleotide sequences of the luxa to luxe genes, as well as the flanking regions, were determined for the lux operons of two xenorhabdus luminescens strains isolated from insects and humans. the nucleotide sequences of the corresponding lux genes (luxcdabe) were 85 to 90% identical but completely diverged 350 bp upstream of the first lux gene (luxc) and immediately downstream of the last lux gene (luxe). these results show that the luxg gene found immediately downstream of luxe in lu ... | 1992 | 1644764 |
| molecular cloning and characterization of the lux genes from the secondary form of xenorhabdus luminescens, k122. | | 1992 | 1633988 |
| isolation and entomotoxic properties of the xenorhabdus nematophilus f1 lecithinase. | xenorhabdus spp. and photorhabdus spp., entomopathogenic bacteria symbiotically associated with nematodes of the families steinernematidae and heterorhabditidae, respectively, were shown to produce different lipases when they were grown on suitable nutrient agar. substrate specificity studies showed that photorhabdus spp. exhibited a broad lipase activity, while most of the xenorhabdus spp. secreted a specific lecithinase. xenorhabdus spp. occur spontaneously in two variants, phase i and phase i ... | 1998 | 9647801 |
| pathogenicity of xenorhabdus luminescens. | | 1992 | 1633985 |
| pcr-ribotyping of xenorhabdus and photorhabdus isolates from the caribbean region in relation to the taxonomy and geographic distribution of their nematode hosts. | the genetic diversity of symbiotic xenorhabdus and photorhabdus bacteria associated with entomopathogenic nematodes was examined by a restriction fragment length polymorphism analysis of pcr-amplified 16s rrna genes (rdnas). a total of 117 strains were studied, most of which were isolated from the caribbean basin after an exhaustive soil sampling. the collection consisted of 77 isolates recovered from entomopathogenic nematodes in 14 caribbean islands and of 40 reference strains belonging to xen ... | 1998 | 9797272 |
| photorhabdus toxins: novel biological insecticides. | following concerns over the potential for insect resistance to insecticidal bacillus thuringiensis toxins expressed in transgenic plants, there has been recent interest in novel biological insecticides. over the past year there has been considerable progress in the cloning of several alternative toxin genes from the bacteria photorhabdus luminescens and xenorhabdus nematophilus. these genes encode large insecticidal toxin complexes with little homology to other known toxins. | 1999 | 10383860 |
| characterization of form variants of xenorhabdus luminescens. | from xenorhabdus luminescens xe-87.3 four variants were isolated. one, which produced a red pigment and antibiotics, was luminescent, and could take up dye from culture media, was considered the primary form (xe-red). a pink-pigmented variant (xe-pink) differed from the primary form only in pigmentation and uptake of dye. of the two other variants, one produced a yellow pigment and fewer antibiotics (xe-yellow), while the other did not produce a pigment or antibiotics (xe-white). both were less ... | 1992 | 1622273 |
| the role of guanosine-3',5'-bis-pyrophosphate in mediating antimicrobial activity of the antibiotic 3,5-dihydroxy-4-ethyl-trans-stilbene. | the mode of action of 3,5-dihydroxy-4-ethyl-trans-stilbene (es), an antibiotic produced by xenorhabdus luminescens symbiotically associated with an entomopathogenic nematode, was investigated. es was active against gram-positive and a number of gram-negative bacteria. in susceptible bacteria this antibiotic caused the inhibition of total rna synthesis and, to a lesser extent, protein synthesis. at or above mics, es triggered a substantial accumulation of an intracellular regulatory compound, gua ... | 1992 | 1282791 |
| immobilization of escherichia coli expressing the lux genes of xenorhabdus luminescens. | the luxcdabe operon of xenorhabdus luminescens was cloned into puc18 to make plite27. expression of the lux genes from the lac promoter resulted in strong constitutive light emission by escherichia coli dh5 carrying the recombinant lux plasmid, plite27. when strain dh5(plite27) was immobilized with sodium alginate-cacl2, the embedded cells retained their luminescence up to 2 weeks under appropriate storage conditions. | 1994 | 7986053 |
| formation of active bacterial luciferase between interspecific subunits in vivo. | interspecific complementation between luxas and luxbs from vibrio harveyi, vibrio fischeri, photobacterium leiognathi and xenorhabdus luminescens was examined in vivo. the individual genes from these species were cloned on different compatible plasmids or amplified by pcr and brought together to yield cis combinations without extraneous dna. the beta subunits from v. harveyi and x. luminescens form active enzyme only with alpha subunits from one of these species. all other combinations yield act ... | 1995 | 7676858 |
| subunit interactions and the role of the luxa polypeptide in controlling thermal stability and catalytic properties in recombinant luciferase hybrids. | bacterial luciferases with over 70% sequence identity from the terrestrial species, xenorhabdus luminescens, and the marine species, vibrio harveyi, exhibit large differences in thermal stability (szittner and meighen, 1990, j. biol. chem. 265, 16581-16587). the origin of these differences was investigated with genetically constructed hybrids containing one subunit from x. luminescens and the other from v. harveyi. while no activity was detected with the single (alpha and beta) subunits both in ... | 1993 | 8399314 |
| phase variation in xenorhabdus luminescens: cloning and sequencing of the lipase gene and analysis of its expression in primary and secondary phases of the bacterium. | the phenomenon of phase variation in the insect-pathogenic bacterium xenorhabdus luminescens was investigated. differential activity of the lipase enzyme (ec 3.1.1.3) was observed between the two phases of the bacteria. the enzyme was found to be secreted into the culture medium, and about five to six times greater specific activity was secreted by the primary phase than by the secondary form. the lipase gene (lip-1) was cloned and sequenced. the data imply that there is only a single tween 80-u ... | 1993 | 8449874 |
| flhdc, the flagellar master operon of xenorhabdus nematophilus: requirement for motility, lipolysis, extracellular hemolysis, and full virulence in insects. | xenorhabdus is a major insect pathogen symbiotically associated with nematodes of the family steinernematidae. this motile bacterium displays swarming behavior on suitable media, but a spontaneous loss of motility is observed as part of a phenomenon designated phase variation which involves the loss of stationary-phase products active as antibiotics and potential virulence factors. to investigate the role of one of the transcriptional activators of flagellar genes, flhdc, in motility and virulen ... | 2000 | 10613869 |
| pathogenicity caused by high virulent and low virulent strains of steinernema carpocapsae to galleria mellonella. | steinernema carpocapsae is an entomopathogenic nematode associated with a symbiotic bacterium, xenorhabdus nematophilus. both components of the complex participate in a pathogenic process in insects. this has raised two questions: how much does each one participate, and what mechanisms are involved? in this paper we compare the virulence of two strains of s. carpocapsae: a high virulent strain (breton) and a low virulent strain (az27), both of which are free of symbiotic bacteria. breton and az2 ... | 2000 | 10631057 |
| pathogenicity, development, and reproduction of heterorhabditis bacteriophora and steinernema carpocapsae under axenic in vivo conditions. | galleria mellonella larvae cultured axenically were treated with axenic dauer juveniles of heterorhabditis bacteriophora and steinernema carpocapsae. after 3 days s. carpocapsae had killed all insects, with 9.4 +/- 4.3 nematodes per larva. h. bacteriophora were unable to kill g. mellonella, although 13.3 +/- 6.4 nematodes per galleria were found in the hemocoel. invading nematodes of both strains recovered from the dauer stage. h. bacteriophora developed into hermaphrodites with eggs and j1 in t ... | 2000 | 10631058 |
| interaction of hemocytes and prophenoloxidase system of fifth instar nymphs of acheta domesticus with bacteria. | the hemocytes to which bacteria adhere were defined and the contribution of the prophenoloxidase system of fifth instar nymphs of acheta domesticus to adhesion were examined. the physicochemical parameters affecting hemocyte and phenoloxidase activity were determined. both plasmatocytes and granular cells responded to bacteria, the latter cells entrapping the microorganisms on filopodial extensions. the optimum ph for hemocyte adhesion to glass slides was 6.5, the granular cells being the most s ... | 2000 | 10736521 |
| inactivation of a novel gene produces a phenotypic variant cell and affects the symbiotic behavior of xenorhabdus nematophilus. | xenorhabdus nematophilus is an insect pathogen that lives in a symbiotic association with a specific entomopathogenic nematode. during prolonged culturing, variant cells arise that are deficient in numerous properties. to understand the genetic mechanism underlying variant cell formation, a transposon mutagenesis approach was taken. three phenotypically similar variant strains of x. nematophilus, each of which contained a single transposon insertion, were isolated. the insertions occurred at dif ... | 2000 | 10742251 |
| eicosanoids rescue spodoptera exigua infected with xenorhabdus nematophilus, the symbiotic bacteria to the entomopathogenic nematode steinernema carpocapsae. | xenorhabdus nematophilus is a pathogenic bacterium causing insect haemolymph septicemia, which leads to host insect death. to address the fundamental mechanisms underlying this haemolymph septicemia, or the immunodepressive response of the host insects following bacterial infection, we tested a hypothesis that the insect immune-mediating eicosanoid pathway is blocked by inhibitory action of the bacterium. haemocoelic injection of the bacteria into the fifth instar larvae of spodoptera exigua red ... | 2000 | 10891575 |
| novel insecticidal toxins from nematode-symbiotic bacteria. | the current strategy of using transgenic crops expressing insecticidal protein toxins is placing increasing emphasis on the discovery of novel toxins, beyond those already derived from the bacterium bacillus thuringiensis. here we review the cloning of four insecticidal toxin complex (tc) encoding genes from a different bacterium photorhabdus luminescens and of similar gene sequences from xenorhabdus nematophilus. both these bacteria occupy the gut of entomopathogenic nematodes and are released ... | 2000 | 10892346 |
| sequence of the luxd gene encoding acyltransferase of the lux operon from photobacterium leiognathi. | the nucleotide sequence of luxd (embl accession no. x65611), encoding acyltransferase (act), of the lux operon from photobacterium leiognathi pl741 was determined, and the amino acid (aa) sequence was deduced. act is a component of the fatty acid reductase complex, which is responsible for converting fatty acid to aldehyde that serves as the substrate in the luciferase-catalyzed bioluminescent reactions. the protein has a calculated m(r) of 34,384 and comprises 305 aa residues. alignment and com ... | 1993 | 8472957 |
| construction and characterization of hybrid luciferases coded by lux genes from xenorhabdus luminescens and vibrio fischeri. | molecular cloning techniques were employed to obtain hybrid luciferases with their alpha and beta subunits encoded by luxa and luxb genes, respectively, from xenorhabdus luminescens strain hw or vibrio fischeri. although the two wild-type luminous bacteria are phylogenetically diverged, the hybrid luciferase xf comprising an alpha from x. luminescens hw and a beta from v. fischeri and the hybrid luciferase vi comprising an alpha from v. fischeri and a beta from x. luminescens hw were both functi ... | 1993 | 8506400 |
| ecology of anti-microbials produced by bacterial associates of steinernema carpocapsae and heterorhabditis bacteriophora. | based on the ability of bacterial associates of entomopathogenic nematodes to produce antibiotic compounds on artificial media, it has been commonly accepted that xenorhabdus sp. and photorhabdus sp. inhibit a wide range of invading microorganisms in insects infected with steinernema spp. or heterorhabditis spp. therefore, the question of whether antibiotic compounds produced by the primary form of bacterial symbionts associated mutualistically with s. carpocapsae and h. bacteriophora explain wh ... | 1996 | 8684829 |
| a new broad-spectrum protease inhibitor from the entomopathogenic bacterium photorhabdus luminescens. | a new protease inhibitor was purified to apparent homogeneity from a culture medium of photorhabdus luminescens by ammonium sulfate precipitation and preparative isoelectric focusing followed by affinity chromatography. ph. luminescens, a bacterium symbiotically associated with the insect-parasitic nematode heterorhabditis bacteriophora, exists in two morphologically distinguishable phases (primary and secondary). it appears that only the secondary-phase bacterium produces this protease inhibito ... | 2000 | 11101672 |
| interaction of xenorhabdus nematophilus (enterobacteriaceae) with the antimicrobial defenses of the house cricket, acheta domesticus. | fifth instar acheta domesticus nymphs exhibited a decline in total hemocyte counts during the first hour of exposure to dead xenorhabdus nematophilus; the bacterial level in the hemolymph also declined during this time. thereafter bacterial numbers in the hemolymph increased as the level of damaged hemocytes increased. the bacteria lowered phenoloxidase activity in vivo by initially reducing the number of hemocytes containing prophenoloxidase and later by inhibiting enzyme activation. preincubat ... | 2000 | 11112374 |
| rapid changes in thermal sensitivity of entomopathogenic nematodes in response to selection at temperature extremes | entomopathogenic nematodes (rhabditida: heterorhabditidae, steinernematidae) are lethal insect parasites that have a symbiotic association with bacteria in the family enterobacteriaceae. we evaluated the changes in thermal sensitivity of two nematodes heterorhabditis bacteriophora and steinernema anomali. the nematodes were genetically selected, together with their respective symbiotic bacteria, at nematodes' reproductive thermal niche breadth extremes, 15° and 30°c, by repeated passage ... | 1996 | 8812571 |
| molecular biology of the symbiotic-pathogenic bacteria xenorhabdus spp. and photorhabdus spp. | | 1996 | 8852894 |
| sequence analysis of insecticidal genes from xenorhabdus nematophilus pmfi296. | three strains of xenorhabdus nematophilus showed insecticidal activity when fed to pieris brassicae (cabbage white butterfly) larvae. from one of these strains (x. nematophilus pmfi296) a cosmid genome library was prepared in escherichia coli and screened for oral insecticidal activity. two overlapping cosmid clones were shown to encode insecticidal proteins, which had activity when expressed in e. coli (50% lethal concentration [lc(50)] of 2 to 6 microg of total protein/g of diet). the complete ... | 2001 | 11319082 |
| two distinct hemolytic activities in xenorhabdus nematophila are active against immunocompetent insect cells. | xenorhabdus spp. and photorhabdus spp. are major insect bacterial pathogens symbiotically associated with nematodes. these bacteria are transported by their nematode hosts into the hemocoel of the insect prey, where they proliferate within hemolymph. in this work we report that wild strains belonging to different species of both genera are able to produce hemolysin activity on blood agar plates. using a hemocyte monolayer bioassay, cytolytic activity against immunocompetent cells from the hemoly ... | 2001 | 11375158 |
| the effect of temperature on the fatty acids and isozymes of a psychrotrophic and two mesophilic species of xenorhabdus, a bacterial symbiont of entomopathogenic nematodes. | in the first part of this study, generation times relative to temperature, together with cardinal and conceptual temperatures, were determined for four strains of xenorhabdus bacteria that represented three geographically distinct species. the data showed that the nf strain of xenorhabdus bovienii, like the umeå strain of the same species, is psychrotrophic, while xenorhabdus sp. tx strain resembles xenorhabdus nematophila all strain in being mesophilic. in the second part, the capacity of these ... | 2001 | 11400727 |
| larvicidal activity of the symbiotic bacterium xenorhabdus japonicus from the entomopathogenic nematode steinernema kushidai against anomala cuprea (coleoptera:scarabaeidae). | the entomopathogenicity of the symbiotic bacterium xenorhabdus japonicus and the nematode steinernema kushidai was determined. phase i and ii x. japonicus were cultured on an artificial medium and inoculated into the test insect or established into axenic s. kushidai populations. when 100, 1000, or 10,000 bacterial cells of phase i or ii were directly injected into the hemocoels of 3rd instar cupreous chafer, anomala cuprea, both phases in the late log period killed 100% of the larvae by the 2nd ... | 1996 | 8858911 |
| xenorhabdus nematophilus as a model for host-bacterium interactions: rpos is necessary for mutualism with nematodes. | xenorhabdus nematophilus, a gram-negative bacterium, is a mutualist of steinernema carpocapsae nematodes and a pathogen of larval-stage insects. we use this organism as a model of host-microbe interactions to identify the functions bacteria require for mutualism, pathogenesis, or both. in many gram-negative bacteria, the transcription factor sigma(s) controls regulons that can mediate stress resistance, survival, or host interactions. therefore, we examined the role of sigma(s) in the ability of ... | 2001 | 11466270 |
| phylogeny of steinernema travassos, 1927 (cephalobina: steinernematidae) inferred from ribosomal dna sequences and morphological characters. | entomopathogenic nematodes in steinernema, together with their symbiont bacteria xenorhabdus, are obligate and lethal parasites of insects that can provide effective biological control of some important lepidopteran, dipteran, and coleopteran pests of commercial crops. phylogenetic relationships among 21 steinernema species were estimated using 28s ribosomal dna (rdna) sequences and morphological characters. sequences of the rdna internal transcribed spacers were obtained to provide additional m ... | 2001 | 11534654 |
| phenotypic and dna relatedness between nematode symbionts and clinical strains of the genus photorhabdus (enterobacteriaceae). | bacterial strains isolated from wide ranges of nematode hosts and geographic sources and strains isolated from human clinical specimens were used to assess the taxonomic structure of the genus photorhabdus. the following two methods were used: dna relatedness and phenotypic characterization. analysis of the dna relatedness data revealed that all of the strains studied were congeneric and that the genus photorhabdus is, on the basis of dna relatedness data, more homogeneous than the other genus o ... | 1996 | 8863433 |
| nucleotide sequence and functional analysis of the luxe gene encoding acyl-protein synthetase of the lux operon from photobacterium leiognathi. | nucleotide sequence of the luxe gene genbank accession no. u66407 from photobacterium leiognathi pl741 has been determined, and the amino acid sequence of acyl-protein synthetase encoded by the luxe gene is deduced. nucleotide sequence reveals that the luxe gene encodes acyl-protein synthetase, which is a component of the fatty acid reductase complex that is responsible for converting fatty acid to aldehyde as substrate in the luciferase-catalyzed bioluminescence reaction. the acyl-protein synth ... | 1996 | 8941351 |
| fast and accurate identification of xenorhabdus and photorhabdus species by restriction analysis of pcr-amplified 16s rrna genes. | thirteen bacterial strains of xenorhabdus and 14 strains of photorhabdus originating from a wide range of geographical and nematode host sources were typed by analyzing 16s rrna gene (rdna) restriction patterns obtained after digestion of pcr-amplified 16s rdnas. eight tetrameric restriction endonucleases were examined. a total of 17 genotypes were identified, forming two heterogeneous main clusters after analysis by the unweighted pair-group method using arithmetic averages: group i included al ... | 1997 | 9023937 |
| purification and characterization of an extracellular protease from xenorhabdus nematophila involved in insect immunosuppression. | xenorhabdus nematophila, a bacterium pathogenic for insects associated with the nematode steinernema carpocapsae, releases high quantities of proteases, which may participate in the virulence against insects. zymogram assays and cross-reactions of antibodies suggested that two distinct proteases were present. the major one, protease ii, was purified and shown to have a molecular mass of 60 kda and an estimated isoelectric point of 8.5. protease ii digested the chromogenic substrate n-tosyl-gly-p ... | 2002 | 11872480 |
| phylogenetic evidence for the taxonomic heterogeneity of photorhabdus luminescens. | the sequences of the 16s rrna gene of 40 strains of bacterial symbionts isolated from the nematodes heterorhabditis spp. and seven bacterial symbionts of the nematodes steinernema spp. which were isolated from different geographical areas, as well as the type strain of xenorhabdus japonicus, were determined and compared to each other and to the sequences of several reference strains of members of the enterobacteriaceae. the data confirmed the separate status of the two genera of symbionts of ent ... | 1997 | 9103628 |
| mechanisms of specificity of association between the nematode steinernema scapterisci and its symbiotic bacterium. | we suggest a new mechanism for the maintenance of specificity of the association between the entomopathogenic nematode steinernema scapterisci and its symbiotic bacteria. we evaluated the development and reproduction of infective and non-infective juvenile s. scapterisci in monoxenic combinations with its symbiotic bacteria, xenorhabdus sp. 's' and with the bacterial symbiont of steinernema carpocapsae and steinernema riobravis. although development of non-infective stages occurred on all xenorh ... | 1997 | 9149419 |
| pathogenicity of axenic steinernema feltiae, xenorhabdus bovienii, and the bacto-helminthic complex to larvae of tipula oleracea (diptera) and galleria mellonella (lepidoptera). | the pathogenicity of the nematode-bacterium complex steinernema feltiae-xenorhabdus bovienii to larvae of tipula oleracea and galleria mellonella was investigated by injection of dauer juvenile nematodes carrying their bacterial symbiont cells (monoxenic nematodes). axenic nematodes (free of bacteria) and the symbiotic bacteria themselves were tested. the lc50 of x. bovienii in t. oleracea was 15,700 colony forming units (cfu)/larva compared to < or = 8 cfu in g. mellonella. xenorhabdus bovienii ... | 1997 | 9170346 |
| identification of xenorhabdus nematophila genes required for mutualistic colonization of steinernema carpocapsae nematodes. | one stage in the symbiotic interaction between the bacterium xenorhabdus nematophila and its nematode host, steinernema carpocapsae, involves the species-specific colonization of the nematode intestinal vesicle by the bacterium. to characterize the bacterial molecular determinants that are essential for vesicle colonization, we adapted and applied a signature-tagged mutagenesis (stm) screen to this system. we identified 15 out of 3000 transposon mutants of x. nematophila with at least a 15-fold ... | 2002 | 12207701 |
| encapsulation of the entomopathogenic nematode steinernema feltiae in tipula oleracea. | the encapsulation response of tipula oleracea to the entomopathogenic nematode steinernema feltiae was investigated by exposing the insects to nematode dauer juveniles (djs) and by injecting djs with and without the symbiotic bacteria xenorhabdus bovienii. the encapsulation response varied considerably between individual insect larvae. the variation could not be attributed to a more or less scattered nematode invasion over time since it was also recorded after simultaneous injection of a fixed d ... | 1997 | 9170347 |
| structure of cell envelope components of the primary and secondary forms of xenorhabdus luminescens. | muropeptide analysis of muramidase-digested murein (peptidoglycan) did not reveal any differences between the primary and secondary forms of xenorhabdus luminescens. similarly, no significant differences were found in the overall protein composition of the cytoplasmic and outer membranes of both forms. | 1997 | 9271844 |
| xenorhabdus nematophila (enterobacteriacea) secretes a cation-selective calcium-independent porin which causes vacuolation of the rough endoplasmic reticulum and cell lysis. | xenorhabdus nematophila and photorhabdus luminescens are two related enterobacteriaceae studied for their use in biological control and for synthesis of original virulence factors and new kinds of antibiotics. x. nematophila broth growth exhibits different cytotoxic activities on insect (spodoptera littoralis, lepidoptera) immunocytes (hemocytes). here we report the purification of the flhdc-dependent cytotoxin, a 10,790-da peptide we have called alpha-xenorhabdolysin (alpha x). we show that pla ... | 2003 | 12441337 |
| characterization of the pleiotropic phenotype of an ompr strain of xenorhabdus nematophila. | xenorhabdus nematophila is an insect pathogen that forms a symbiotic association with the nematode, steinernema carpocapsae. xenorhabdus is carried into the insect host by the nematode, is released into the hemolymph and participates in killing the insect. the bacteria grow to high concentrations supporting the development of the nematode in the hemolymph. ompr is a global regulatory protein involved in the regulation of porin genes, motility, acid tolerance and virulence in several enteric bact ... | 2002 | 12448704 |
| response of ants to a deterrent factor(s) produced by the symbiotic bacteria of entomopathogenic nematodes. | the production of an ant-deterrent factor(s) (adf) by xenorhabdus nematophila and photorhabdus luminescens, the symbiotic bacteria of the nematodes steinernema carpocapsae and heterorhabditis bacteriophora, respectively, was examined. in addition to an in vivo assay in which bacteria were tested for their ability to produce adf within insect cadavers (m.e. baur, h. k. kaya, and d. r. strong, biol. control 12:231-236, 1998), an in vitro microtiter dish assay was developed to monitor adf activity ... | 2002 | 12450845 |
| phylogeny of photorhabdus and xenorhabdus species and strains as determined by comparison of partial 16s rrna gene sequences. | partial 16s rrna gene sequences of 16 strains of the genera photorhabdus and xenorhabdus were determined by direct sequencing of pcr products. aligned sequences were subjected to phylogenetic analysis by maximum-likelihood and maximum-parsimony methods. distance matrix and phylogenetic analysis did not separate the genera unambiguously. taxonomic grouping of the bacteria closely paralleled taxonomic grouping of their nematode associates and their geographic origins. we found at least two well-su ... | 1997 | 9336891 |
| n-phenethyl-2-phenylacetamide isolated from xenorhabdus nematophilus induces apoptosis through caspase activation and calpain-mediated bax cleavage in u937 cells. | the present study was designed to assess the mechanism of n-phenethyl-2-phenylacetamide (nppa), one of three new compounds isolated from xenorhabdus nematophilus, on the induction of apoptosis in u937 cells. nppa displayed strong inhibitory effects on cell proliferation and viability of u937 cells and induced apoptosis. investigation of the mechanism of nppa-induced apoptosis revealed that treatment with nppa produced morphological features of apoptosis and dna fragmentation. this was associated ... | 2003 | 12469198 |
| generation and properties of a luminescent insect pathogen xenorhabdus nematophilus (enterobacteriaceae). | studies on the interaction of the insect pathogenic bacterium, xenorhabdus nematophilus (enterobacteriaceae), with its nematode and insect hosts would be greatly assisted if a luminescent phenotype were generated that would allow the detection of viable bacteria in vivo without the necessity for disruption of the cellular interactions. the plasmid, pmgm221, containing the luminescence gene (luxcdabe) of vibrio harveyi was introduced into different strains (dd136 and 19061) and phases (one and tw ... | 1998 | 12501420 |
| the bacterium xenorhabdus nematophilus depresses nodulation reactions to infection by inhibiting eicosanoid biosynthesis in tobacco hornworms, manduca sexta. | the bacterium, xenorhabdus nematophilus, is a virulent insect pathogen. we tested the hypothesis that this bacterium impairs insect cellular immune defense reactions by inhibiting biosynthesis of eicosanoids involved in mediating cellular defense reactions. fifth instar tobacco hornworms, manduca sexta, produced melanized nodules in reaction to challenge with living and heat-killed x. nematophilus. however, the nodulation reactions were much attenuated in insects challenged with living bacteria ... | 2003 | 12529862 |
| xenorhabdus and photorhabdus spp.: bugs that kill bugs. | xenorhabdus and photorhabdus spp. are gram negative gamma proteobacteria that form entomopathogenic symbioses with soil nematodes. they undergo a complex life cycle that involves a symbiotic stage, in which the bacteria are carried in the gut of the nematodes, and a pathogenic stage, in which susceptible insect prey are killed by the combined action of the nematode and the bacteria. both bacteria produce antibiotics, intracellular protein crystals, and numerous other products. these traits chang ... | 1997 | 9343343 |
| h-ns protein represses transcription of the lux systems of vibrio fischeri and other luminous bacteria cloned into escherichia coli. | high expression in escherichia coli of the lux system cistron of a luminous bacteria under its own control has been accomplished only for the vibrio fischeri lux system at high cell density. mutation of the hns gene in e. coli has resulted in strong expression of the v. fischeri lux system at low cell density even in an rpos-deleted strain of e. coli that emits very low levels of luminescence. the e. coli double mutant, mc4110 hns::kan rpos::tet carrying the lux system of v. fischeri, developed ... | 1997 | 9353217 |
| universal ribotyping method using a chemically labelled oligonucleotide probe mixture. | some of the present problems in ribotyping are associated with a lack of uniform reactivity of probes when bacterial dnas are of phylogenetically diverse origins. to overcome these problems, a set of five oligonucleotides (referred to as oligomix5) was selected to react with conserved sequences located near both extremities of rrs (16s rrna gene) and near both extremities and the middle of rrl (23s rrna gene). dna samples from 13 bacterial species selected to represent various phylogenetic branc ... | 1997 | 9765850 |
| holin locus characterisation from lysogenic xenorhabdus nematophila and its involvement in escherichia coli shea haemolytic phenotype. | lysogeny has previously been described in the entomopathogenic bacteria of the genus xenorhabdus. screening of a x. nematophila prophage dna library on blood agar resulted in the identification of a 5.7-kb locus that caused a haemolytic phenotype when cloned in escherichia coli, but not in the e. coli shea null mutant, lacking the shea cryptic haemolysin. this locus exhibited similarity to lysis genes from lambdoid phages. in particular, it encoded a functional holin able to complement a lambda ... | 2003 | 12583905 |
| occurrence of p-flavin binding protein in vibrio fischeri and properties of the protein. | in previous studies involving photobacterium species we proposed that (i) p-flavin is the product of luciferase, (ii) the physiological function of the lux operon is not to produce light but to produce fp(390) (luxf protein), including its prosthetic group, p-flavin, and (iii) fp(390) reactivates oxidatively inactivated cobalamin-dependent methionine synthase similar to flavodoxin but at relatively high ionic strength. it seems difficult to extend this idea to all luminous bacteria because the l ... | 1999 | 10423522 |
| insecticidal activity associated with the outer membrane vesicles of xenorhabdus nematophilus. | xenorhabdus nematophilus secretes a large number of proteins into the culture supernatant as soluble proteins and also as large molecular complexes associated with the outer membrane. transmission electron micrographs of x. nematophilus cells showed that there was blebbing of the outer membrane from the surface of the bacterium. the naturally secreted outer membrane vesicles (omvs) were purified from the culture supernatant of x. nematophilus and analyzed. electron microscopy revealed a vesicula ... | 2003 | 12676679 |
| isolation, identification, and molecular characterization of strains of photorhabdus luminescens from infected humans in australia. | we describe the isolation of photorhabdus (xenorhabdus) luminescens from four australian patients: two with multiple skin lesions, one with bacteremia only, and one with disseminated infection. one of the patients had multiple skin lesions following the bite of a spider, while the lesions in the other patient were possibly associated with a spider bite. the source of infection for the remaining two patients is unknown. as a member of the family enterobacteriaceae, p. luminescens is unusual in th ... | 1999 | 10523568 |
| early colonization events in the mutualistic association between steinernema carpocapsae nematodes and xenorhabdus nematophila bacteria. | the bacterium xenorhabdus nematophila is a mutualist of the entomopathogenic nematode steinernema carpocapsae. during its life cycle, the bacterium exists both separately from the nematode and as an intestinal resident of a nonfeeding nematode form, the infective juvenile (ij). the progression of x. nematophila from an ex vivo existence to a specific and persistent colonization of ijs is a model to understand the mechanisms mediating the initiation and maintenance of benign host-microbe interact ... | 2003 | 12730175 |
| insect immunity-effects of factors produced by a nematobacterial complex on immunocompetent cells(1). | during in vitro incubations, the nematobacterial complex steinernema carpocapsae-xenorhabdus nematophilus produces different factors having toxic activities in vitro towards haemocytes, the insect cells responsible for cellular immune defense reactions. among others, two effects were evident on haemocyte monolayers; one of them was a cytotoxic activity while the other was an unsticking effect. the factors responsible for cytotoxic activity and unsticking effect, were separated from each other by ... | 1999 | 12770353 |