| [importance of five genes presented in xenorhabdus nematophilus bp toxin gene cluster to its insecticidal activity]. | importance of five genes, named as xpta1, xptd1, xptb1, xptc1 and xpta2 presented in the toxin gene cluster of x. nematophilus bp strain, to its insecticidal activity against the neonate of helicorvepa armigera was examined. this was achieved by analyzing and comparing the presence or absence of these five genes in and the insecticidal activity of each of the five clones screened from genomic cosmid library of x. nematophilus bp by in situ hybridization and another three subclones constructed fr ... | 2003 | 16276896 |
| the steinernema carpocapsae intestinal vesicle contains a subcellular structure with which xenorhabdus nematophila associates during colonization initiation. | steinernema carpocapsae infective juvenile (ij) nematodes are intestinally colonized by mutualistic xenorhabdus nematophila bacteria. during ij development, a small number of ingested x. nematophila cells initiate colonization in an anterior region of the intestine termed the vesicle and subsequently multiply within this host niche. we hypothesize that efficient colonization of a high percentage of s. carpocapsae individuals (typically>85%) is facilitated by bacterial adherence to a site(s) in t ... | 2005 | 16309459 |
| characterization of tn5-induced mutants of xenorhabdus nematophilus atcc 19061. | a negative-selection vector, phx1, was constructed for use in transposon mutagenesis of xenorhabdus nematophilus atcc 19061. phx1 contains the bacillus subtilis levansucrase gene which confers sucrose sensitivity. in addition, various tn5-containing plasmids with different replication origins were transferred by conjugation from escherichia coli into x. nematophilus atcc 19061, and one of these plasmids, pgs9, yields tn5 insertion mutants of x. nematophilus atcc 19061. by using these two deliver ... | 1991 | 16348462 |
| phase variation in xenorhabdus nematophilus and photorhabdus luminescens: differences in respiratory activity and membrane energization. | phase variation in xenorhabdus and photorhabdus spp. has a significant impact on their symbiotic relationship with entomopathogenic nematodes by altering the metabolic by-products upon which the nematodes feed. the preferential retention of the phase i variant by the infective-stage nematode and its better support for nematode reproduction than phase ii indicates its importance in the bacterial-nematode interactions. however, there is no obvious role for phase ii in these interactions. this stud ... | 1994 | 16349145 |
| stability and activities of antibiotics produced during infection of the insect galleria mellonella by two isolates of xenorhabdus nematophilus. | xenorhabdus nematophilus subsp. dutki, an entomopathogenic bacterium, is vectored by steinernematid nematodes into insects, where it produces broad-spectrum antibiotics. the use of the nematode-bacterium complex against soil-dwelling pest insects could introduce antibiotics into the soil via the dead insect fragments during the emergence phase of the nematodes. studies on the stability and activities of these antibiotics produced in the insect galleria mellonella may contribute to assessing the ... | 1994 | 16349198 |
| phase variation in xenorhabdus nematophilus. | xenorhabdus nematophilus is a symbiotic bacterium that inhabits the intestine of entomopathogenic nematodes. the bacterium-nematode symbiotic pair is pathogenic for larval-stage insects. the phase i cell type is the form of the bacterium normally associated with the nematode. a variant cell type, referred to as phase ii, can form spontaneously under stationary-phase conditions. phase ii cells do not elaborate products normally associated with the phase i cell type. to better define phase variati ... | 1998 | 16349534 |
| low temperature-induced insecticidal activity of yersinia enterocolitica. | the insecticidal toxin complexes (tcs) are produced by several enterobacteriaceae associated with insects, such as photorhabdus luminescens, serratia entomophila and xenorhabdus nematophilus. genome sequences revealed tc-like genes in yersinia spp., but insecticidal activity of this genus associated with the toxins has not been described. through the search for genes upregulated at low growth temperatures in yersinia enterocolitica strain w22703, a genomic island of 19 kb termed tc-pai(ye) with ... | 2006 | 16390445 |
| txp40, a ubiquitous insecticidal toxin protein from xenorhabdus and photorhabdus bacteria. | xenorhabdus and photorhabdus are gram-negative bacteria that produce a range of proteins that are toxic to insects. we recently identified a novel 42-kda protein from xenorhabdus nematophila that was lethal to the larvae of insects such as galleria mellonella and helicoverpa armigera when it was injected at doses of 30 to 40 ng/g larvae. in the present work, the toxin gene txp40 was identified in another 59 strains of xenorhabdus and photorhabdus, indicating that it is both highly conserved and ... | 2006 | 16461722 |
| monoxenic liquid culture of the entomopathogenic nematode steinernema carpocapsae using a culture medium containing whey kinetics and modeling. | the submerged culture of the entomopathogenic nematode steinernema carpocapsae and its symbiotic bacterium, xenorhabdus nematophila, was carried out in orbitally agitated bottles using a culture medium containing whey (in grams per litre: 500 whey, 20 yeast extract, 10 dried egg yolk-food grade, 3 sodium chloride, 37 corn oil-food grade). maximum total viable nematode concentrations of 198,333ml(-1) were achieved within fermentations of 24 days with 64% of the nematode population within the infe ... | 2006 | 16516997 |
| swarming and swimming changes concomitant with phase variation in xenorhabdus nematophilus. | xenorhabdus spp., entomopathogenic bacteria symbiotically associated with nematodes of the family steinernematidae, occur spontaneously in two phases. phase i, the variant naturally isolated from the infective-stage nematode, provides better conditions than the phase ii variant for nematode reproduction. this study has shown that xenorhabdus phase i variants displayed a swarming motility when they were grown on a suitable solid medium (0.6 to 1.2% agar). whereas most of the phase i variants from ... | 1995 | 16534993 |
| biochemical characterization and agglutinating properties of xenorhabdus nematophilus f1 fimbriae. | xenorhabdus spp., entomopathogenic bacteria symbiotically associated with nematodes of the family steinernematidae, occur spontaneously in two phases. only the phase i variants of xenorhabdus nematophilus f1 expressed fimbriae when the bacteria were grown on a solid medium (nutrient agar; 24 and 48 h of growth). these appendages were purified and characterized. they were rigid, with a diameter of 6.4 (plusmn) 0.3 nm, and were composed of 16-kda pilin subunits. the latter were synthesized and ass ... | 1995 | 16535079 |
| composition and biophysical properties of lipids in xenorhabdus nematophilus and photorhabdus luminescens, symbiotic bacteria associated with entomopathogenic nematodes. | primary and secondary forms of photorhabdus luminescens hm and xenorhabdus nematophilus n2-4 were grown at 18 and 28(deg)c for 24 to 96 h, and we made determinations of the fatty-acid compositions of total lipids and of the fluidity measured by 5-doxyl-stearic acid embedded in liposomes made from total lipids. the levels of the unsaturated fatty acids 16:1 and 18:1 (those with chain lengths of 16 or 18 and one double bond) generally were higher in primary-phase variants of p. luminescens grown a ... | 1997 | 16535651 |
| analysis of the pixa inclusion body protein of xenorhabdus nematophila. | the symbiotic pathogenic bacterium xenorhabdus nematophila produces two distinct intracellular inclusion bodies. the pixa gene, which encodes the 185-residue methionine-rich pixa inclusion body protein, was analyzed in the present study. the pixa gene was optimally expressed under stationary-phase conditions but its expression did not require rpos. analysis of a pixa mutant strain showed that pixa was not required for virulence towards the insect host or for colonization of or survival within th ... | 2006 | 16547059 |
| co-regulation of motility, exoenzyme and antibiotic production by the envz-ompr-flhdc-flia pathway in xenorhabdus nematophila. | xenorhabdus nematophila is an emerging model for both mutualism and pathogenicity in different invertebrate hosts. here we conduct a mutant study of the envz-ompr two-component system and the flagella sigma factor, flia (sigma28). both ompr and envz strains displayed precocious swarming behaviour, elevated flhd and flia mrna levels and early production of lipase, protease, haemolysin and antibiotic activity. inactivation of flia eliminated exoenzyme production which was restored by complementati ... | 2006 | 16889644 |
| stability of entomopathogenic bacteria, xenorhabdus nematophila and photorhabdus luminescens, during in vitro culture. | the entomopathogenic nematode-bacteria complexes heterorhabditis bacteriophora/photorhabdus luminescens and steinernema carpocapsae/xenorhabdus nematophila are mass produced for use as biological insecticides. stability of the bacterial partner in culture is essential for maintaining traits important for both biological control and production. two geographically distinct strains of each bacterial species were isolated from their nematode partners and serially subcultured on in vitro media to ass ... | 2007 | 16941119 |
| the cytotoxic fimbrial structural subunit of xenorhabdus nematophila is a pore-forming toxin. | we have purified a fimbrial shaft protein (mrxa) of xenorhabdus nematophila. the soluble monomeric protein lysed larval hemocytes of helicoverpa armigera. osmotic protection of the cells with polyethylene glycol suggested that the 17-kda mrxa subunit makes pores in the target cell membrane. the internal diameter of the pores was estimated to be >2.9 nm. electron microscopy confirmed the formation of pores by the fimbrial subunit. mrxa protein oligomerized in the presence of liposomes. electrophy ... | 2006 | 16950919 |
| identification, typing, and insecticidal activity of xenorhabdus isolates from entomopathogenic nematodes in united kingdom soil and characterization of the xpt toxin loci. | xenorhabdus strains from entomopathogenic nematodes isolated from united kingdom soils by using the insect bait entrapment method were characterized by partial sequencing of the 16s rrna gene, four housekeeping genes (asd, ompr, reca, and serc) and the flagellin gene (flic). most strains (191/197) were found to have genes with greatest similarity to those of xenorhabdus bovienii, and the remaining six strains had genes most similar to those of xenorhabdus nematophila. generally, 16s rrna sequenc ... | 2006 | 16957209 |
| clonal variation in xenorhabdus nematophila virulence and suppression of manduca sexta immunity. | virulence of the insect pathogen xenorhabdus nematophila is attributed in part to its ability to suppress immunity. for example, x. nematophila suppresses transcripts encoding several antimicrobial proteins, even in the presence of salmonella enterica, an inducer of these transcripts. we show here that virulence and immune suppression phenotypes can be lost in a subpopulation of x. nematophila. cells that have undergone 'virulence modulation' (vmo) have attenuated virulence and fail to suppress ... | 2007 | 17002783 |
| interaction of the bacteria xenorhabdus nematophila (enterobactericeae) and bacillus subtilis (bacillaceae) with the hemocytes of larval malacosoma disstria (insecta: lepidoptera: lasiocampidae). | malacosoma disstria larvae are a pest of deciduous trees. little is known on the interaction of bacteria with the immediate hemocytic antimicrobial responses of these insects. incubating dead xenorhabdus nematophila and bacillus subtilis with a mixture of serum-free granular cells and plasmatocytes in vitro revealed differential bacterial-hemocyte adhesion and differential discharge of lysozyme and phenoloxidase but not total protein. although active phenoloxidase adhered equally to both bacteri ... | 2007 | 17022997 |
| nilr is necessary for co-ordinate repression of xenorhabdus nematophila mutualism genes. | the bacterial mutualist xenorhabdus nematophila colonizes a specific region of its nematode host steinernema carpocapsae. we previously reported the identification of a chromosomal locus encoding three x. nematophila genes of unknown function, nila, b and c, that are each necessary for colonization. subsequent work indicated the global regulator lrp is a repressor of nilc: nilc transcription is elevated in an lrp mutant and lrp interacts directly with the nilc promoter. in this manuscript, we re ... | 2006 | 17076669 |
| the global regulator lrp contributes to mutualism, pathogenesis and phenotypic variation in the bacterium xenorhabdus nematophila. | xenorhabdus nematophila is a gram-negative bacterium that leads both pathogenic and mutualistic lifestyles. in this study, we examine the role of lrp, the leucine-responsive regulatory protein, in regulating both of these lifestyles. lrp mutants have attenuated virulence towards manduca sexta insects and are defective in suppression of both cellular and humoral insect immunity. in addition, an lrp mutant is deficient in initiating colonization of and growth within mutualistic host nematodes. fur ... | 2007 | 17223926 |
| the xaxab genes encoding a new apoptotic toxin from the insect pathogen xenorhabdus nematophila are present in plant and human pathogens. | xenorhabdus nematophila, a member of the enterobacteriaceae, kills many species of insects by strongly depressing the immune system and colonizing the entire body. a peptide cytotoxin has been purified from x. nematophila broth growth, and the cytolytic effect on insect immunocytes and hemolytic effect on mammalian red blood cells of this toxin have been described (ribeiro, c., vignes, m., and brehélin, m. (2003) j. biol. chem. 278, 3030-3039). we show here that this toxin, xenorhabdus alpha-xen ... | 2007 | 17229739 |
| submerged monoxenic culture of the entomopathogenic nematode steinernema carpocapsae in an internal-loop airlift bioreactor using two configurations of the inner tube. | this article reports the submerged culture of the entomopathogenic nematode steinernema carpocapsae and its symbiotic bacterium, xenorhabdus nematophila, within an internal-loop airlift bioreactor. two configurations of the inner cylinder were tested: a standard draft tube (sdt) and a static mixer (sm), as well as two production media: mp1 (500 ml/l whey, among other ingredients) and mp2 (82 ml/l agave-juice from agave spp., among other ingredients). three fermentations were carried out: f1 --> ... | 2007 | 17252612 |
| structural characterisation of the insecticidal toxin xpta1, reveals a 1.15 mda tetramer with a cage-like structure. | a recently identified class of proteins conferring insecticidal activity to several bacteria within the enterobacteriaceae family have potential for control of commercially important insect pests. here, we report the first purification, biophysical characterisation and 3-d structural analysis of one of the toxin components, xpta1, from xenorhabdus nematophila pmfi296 to a resolution of 23 a. membrane binding studies indicate that the three-component toxin system has a different mode of action fr ... | 2007 | 17266984 |
| potentiating effect of bacillus thuringiensis subsp. kurstaki on pathogenicity of entomopathogenic bacterium xenorhabdus nematophila k1 against diamondback moth (lepidoptera: plutellidae). | xenorhabdus nematophila is the symbiotic bacterium of an entomopathogenic nematode, steinernema carpocapsae. when the nematode enters a target insect, the symbiotic bacteria are released into the hemocoel. after inducing host immunosuppression, the bacteria multiply in the hemocoel and cause fatal septicemia. for optimal field application to control insect pests, culturing mass numbers of the nematodes would be costly. in this study, bacillus thuringiensis (bt) was chosen as an alternative natur ... | 2007 | 17370835 |
| influence of nematode age and culture conditions on morphological and physiological parameters in the bacterial vesicle of steinernema carpocapsae (nematoda: steinernematidae). | steinernema spp. third-stage infective juveniles (ijs) play a key role in the symbiotic partnership between these entomopathogenic nematodes and xenorhabdus bacteria. recent studies suggest that steinernema carpocapsae ijs contribute to the nutrition and growth of their symbionts in the colonization site (vesicle) [martens, e.c. and goodrich-blair, h., 2005. the s. carpocapsae intestinal vesicle contains a sub-cellular structure with which xenorhabdus nematophila associates during colonization i ... | 2007 | 17376477 |
| application of toxins from the entomopathogenic bacterium, xenorhabdus nematophila, for the control of insects on foliage. | larvae of the beet armyworm, spodoptera exigua, and the diamondback moth, plutella xylostella, and nymphs of the desert locust, schistocerca gregaria were controlled by the application of either cell suspensions from the bacterium, xenorhabdus nematophila or filtrates containing cell-free toxins. since there was no significant differences between the two treatments it was concluded that toxins produced by the bacterium were responsible for the lethal effects obtained. cells of xenorhabdus nemato ... | 2006 | 17390798 |
| diversity in pathogenicity of steinernema carpocapsae and its symbiotic bacterium for spodoptera spp. | pathogenicity of five isolates of steinernema carpocapsae (ger: germany, buw: becker underwood, kop: koppert, cz: czech republic, bel: belgium) were tested against the fourth instar larvae of the cotton leaf worm, spodoptera littoralis and the beet armyworm, spodoptera exigua (lepidoptera: noctuidae) at different concentrations (0, 5, 10, 25, and 50 infective juveniles/cm2) in petri dishes (9 cm dia.) lined with filter paper. results obtained after 48 h exposure indicated that the pathogenicity ... | 2006 | 17390810 |
| an entomopathogenic bacterium, xenorhabdus nematophila, inhibits hemocyte phagocytosis of spodoptera exigua by inhibiting phospholipase a(2). | phagocytosis is a hemocytic behavior against bacterial infection. an entomopathogenic bacterium, xenorhabdus nematophila, inhibits immune responses of target insects and causes hemolymph septicemia. this study analyzed how x. nematophila could inhibit phagocytosis to increase its pathogenicity. granular cells and plasmatocytes were the main phagocytic hemocytes of spodoptera exigua determined by observing fluorescence-labeled bacteria in the cytosol. x. nematophila significantly inhibited phagoc ... | 2007 | 17395196 |
| new insights into the colonization and release processes of xenorhabdus nematophila and the morphology and ultrastructure of the bacterial receptacle of its nematode host, steinernema carpocapsae. | we present results from epifluorescence, differential interference contrast, and transmission electron microscopy showing that xenorhabdus nematophila colonizes a receptacle in the anterior intestine of the infective juvenile (ij) stage of steinernema carpocapsae. this region is connected to the esophagus at the esophagointestinal junction. the process by which x. nematophila leaves this bacterial receptacle had not been analyzed previously. in this study we monitored the movement of green fluor ... | 2007 | 17526783 |
| enhanced antibiotic activity of xenorhabdus nematophila by medium optimization. | nutrition had highly influence on the antibiotic production by xenorhabdus nematophila yl001. glucose and peptone were identified as the best carbon and nitrogen sources that significantly affected antibiotic production using one-factor-at-a-time approach. response surface methodology was applied to optimize the medium constituents (glucose, peptone and minerals) for antibiotic production by x. nematophila yl001. higher antibiotic activity (328.9 u/ml) was obtained after optimizing medium compon ... | 2008 | 17531470 |
| they've got a ticket to ride: xenorhabdus nematophila-steinernema carpocapsae symbiosis. | the association between the bacterium xenorhabdus nematophila and the nematode steinernema carpocapsae is emerging as a model system to understand mutually beneficial symbioses. x. nematophila, but not other xenorhabdus species, colonize a discrete region of a specific developmental stage of s. carpocapsae nematodes. recent progress has led to the identification of bacterial genes necessary for colonization. furthermore, new details have been elucidated regarding the morphology and physiology of ... | 2007 | 17553732 |
| friend and foe: the two faces of xenorhabdus nematophila. | comparisons of mutualistic and pathogenic relationships are necessary to decipher the common language of microorganism-host interactions, as well as the subtle differences in dialect that distinguish types of symbiosis. one avenue towards making such comparisons is to study a single organism that speaks both dialects, such as the gamma-proteobacterium xenorhabdus nematophila. x. nematophila inhabits and influences the lives of two host animals, helping one to reproduce optimally while killing th ... | 2007 | 17618298 |
| cpxra regulates mutualism and pathogenesis in xenorhabdus nematophila. | the cpxra signal transduction system, which in escherichia coli regulates surface structure assembly and envelope maintenance, is involved in the pathogenic and mutualistic interactions of the entomopathogenic bacterium xenorhabdus nematophila. when deltacpxr1 cells were injected into manduca sexta insects, the time required to kill 50% of the insects was twofold longer than the time observed for wild-type cells and the deltacpxr1 cells ultimately killed 16% fewer insects than wild-type cells ki ... | 2007 | 17951441 |
| optimization of fermentation condition for antibiotic production by xenorhabdus nematophila with response surface methodology. | to evaluate the influence of environmental parameters on the production of antibiotics (xenocoumacins and nematophin) by xenorhabdus nematophila and enhance the antibiotic activity. | 2008 | 17953686 |
| surface antigens of xenorhabdus nematophila (f. enterobacteriaceae) and bacillus subtilis (f. bacillaceae) react with antibacterial factors of malacosoma disstria (c. insecta: o. lepidoptera) hemolymph. | previous research established different interactions of the insect pathogen, xenorhabdus nematophila and nonpathogen, bacillus subtilis, with antimicrobial hemocytes and humoral factors of larval malacosoma disstria [giannoulis, p., brooks, c.l., dunphy, g.b., mandato, c.a., niven, d.f., zakarian, r.j., 2007. interaction of the bacteria xenorhabdus nematophila (enterobacteriaceae) and bacillus subtilis (bacillaceae) with the hemocytes of larval malacosoma disstria (insecta: lepidoptera: lasicoca ... | 2008 | 18048054 |
| eicosanoids mediate prophenoloxidase release from oenocytoids in the beet armyworm spodoptera exigua. | phenoloxidase (po) plays a critical role in insect immune reactions especially to form melanotic encapsulation and phagocytosis by hemocytes. po is an active form of prophenoloxidase (ppo) after proteolytic cleavage by serine proteinase(s). it has been suggested that eicosanoids are implicated in ppo activation in the beet armyworm, spodoptera exigua. however, it is not clear how eicosanoids mediate the reaction cascade of ppo activation. this study analyzed the ppo activation mediated by eicosa ... | 2008 | 18070669 |
| type 1 fimbriae of insecticidal bacterium xenorhabdus nematophila is necessary for growth and colonization of its symbiotic host nematode steinernema carpocapsiae. | xenorhabdus nematophila produces type 1 fimbriae on the surface of phase i cells. fimbriae mediate recognition and adhesion of the bacteria to its target cell. to investigate the role of fimbriae in the biology of x. nematophila, we have produced a fimbrial mutant strain by insertional inactivation of the mrxa gene, encoding the structural subunit of type 1 fimbriae. phenotypic characterization of the mutant revealed loss of fimbriae on the cell surface. cell surface characteristics like dye abs ... | 2008 | 18279345 |
| benzylideneacetone, an immunosuppressant, enhances virulence of bacillus thuringiensis against beet armyworm (lepidoptera: noctuidae). | benzylideneacetone (bza) is a metabolite of gram-negative entomopathogenic bacterium xenorhabdus nematophila, and it acts as an enzyme inhibitor against phospholipase a2 (pla2). pla2 catalyzes a committed biosynthetic step of eicosanoids, which mediate insect immune reactions to infection by microbial pathogens. this study tested a hypothesis that a putative immunosuppressive activity of bza may enhance virulence of bacillus thuringiensis against the fifth instars of spodoptera exigua (hübner) ( ... | 2008 | 18330113 |
| transcriptional analysis and functional characterization of a gene pair encoding iron-regulated xenocin and immunity proteins of xenorhabdus nematophila. | we describe a two-gene cluster encoding a bacteriocin, xenocin, and the cognate immunity protein in the insect-pathogenic bacterium xenorhabdus nematophila, which infects and kills larval stages of the common crop pest helicoverpa armigera. the two genes, xcina and ximb, are present in the genome as a single transcriptional unit, which is regulated under sos conditions. the stress-inducible promoter was activated by mitomycin c, glucose, and fe(3+) depletion and at an elevated temperature when i ... | 2008 | 18375563 |
| fliz, a flagellar regulator, is at the crossroads between motility, haemolysin expression and virulence in the insect pathogenic bacterium xenorhabdus. | there is a complex interplay between the regulation of flagellar motility and the expression of virulence factors in many bacterial pathogens. we investigated the role of fliz in the regulation of flagellar and virulence genes in xenorhabdus nematophila, an insect pathogen. the fliz gene is the second gene in the fliaz operon in x. nematophila. in vivo transcription analysis revealed a positive feedback loop of fliaz transcription in which fliz activates flhdc, the master operon of flagellar reg ... | 2008 | 18383616 |
| the xenorhabdus nematophila nilabc genes confer the ability of xenorhabdus spp. to colonize steinernema carpocapsae nematodes. | members of the steinernema genus of nematodes are colonized mutualistically by members of the xenorhabdus genus of bacteria. in nature, steinernema carpocapsae nematodes are always found in association with xenorhabdus nematophila bacteria. thus, this interaction, like many microbe-host associations, appears to be species specific. x. nematophila requires the nila, nilb, and nilc genes to colonize s. carpocapsae. in this work, we showed that of all the xenorhabdus species examined, only x. nemat ... | 2008 | 18390667 |
| linear and cyclic peptides from the entomopathogenic bacterium xenorhabdus nematophilus. | three new peptides, xenortides a and b and xenematide, were isolated from a culture of the nematode-associated entomopathogenic bacterium xenorhabdus nematophilus. their structures were elucidated using nmr, ms, and chemical derivatization methods. xenortides a and b are the n-phenethylamide and tryptamide derivatives, respectively, of the dipeptide (nme-l-leu-nme-l-phe). the cyclodepsipeptide xenematide has the sequence (thr-trp-trp-gly), with a 2-phenylacetamide substituent at the threonine re ... | 2008 | 18491867 |
| xenorhabdus nematophila lrha is necessary for motility, lipase activity, toxin expression, and virulence in manduca sexta insects. | the gram-negative insect pathogen xenorhabdus nematophila possesses potential virulence factors including an assortment of toxins, degradative enzymes, and regulators of these compounds. here, we describe the lysr-like homolog a (lrha) gene, a gene required by x. nematophila for full virulence in manduca sexta insects. in several other gram-negative bacteria, lrha homologs are transcriptional regulators involved in the expression (typically repression) of virulence factors. based on phenotypic a ... | 2008 | 18502863 |
| the hmshfrs operon of xenorhabdus nematophila is required for biofilm attachment to caenorhabditis elegans. | the bacterium xenorhabdus nematophila is an insect pathogen and an obligate symbiont of the nematode steinernema carpocapsae. x. nematophila makes a biofilm that adheres to the head of the model nematode caenorhabditis elegans, a capability x. nematophila shares with the biofilms made by yersinia pestis and yersinia pseudotuberculosis. as in yersinia spp., the x. nematophila biofilm requires a 4-gene operon, hmshfrs. also like its yersinia counterparts, the x. nematophila biofilm is bound by the ... | 2008 | 18515487 |
| low migration decreases interference competition among parasites and increases virulence. | competition among different parasite genotypes within a host is predicted to affect virulence. the direction of this effect, however, depends critically on the mechanisms that parasites use to compete or to cooperate with each other. one mechanism that bacteria use to compete with each other is via the production of bacteria-killing toxins, called bacteriocins. this warfare among parasites within a host is predicted to reduce the rate of host exploitation, resulting in lower virulence. by contra ... | 2008 | 18636975 |
| characterization of the gut bacterial community in manduca sexta and effect of antibiotics on bacterial diversity and nematode reproduction. | the tobacco hornworm, manduca sexta, is a model lepidopteran insect used to study the pathogenic and mutualistic phases of entomopathogenic nematodes (epns) and their bacterial symbionts. while intestinal microbial communities could potentially compete with the epn and its bacterial partner for nutrient resources of the insect, the microbial gut community had not been characterized previously. here, we show that the midgut of m. sexta raised on an artificial diet contained mostly gram-positive c ... | 2008 | 18647359 |
| [purification and characterization of the haemocoel insecticide tp40 from xenorhabdus nematophila]. | xenorhabdus nematophila is an insect pathogen bacterium symbiotically associated with entomopathogenic nematode. the bacteria produce a number of toxins to overcome immune response of insect hosts and kill their hosts. we purified a novel haemocoel insecticidal protein from x. nematophila hb310, cloned and analysed gene sequence of this novel protein. | 2008 | 18652303 |
| an insecticidal groel protein with chitin binding activity from xenorhabdus nematophila. | xenorhabdus nematophila secretes insecticidal proteins to kill its larval prey. we have isolated an approximately 58-kda groel homolog, secreted in the culture medium through outer membrane vesicles. the protein was orally insecticidal to the major crop pest helicoverpa armigera with an lc50 of approximately 3.6 microg/g diet. for optimal insecticidal activity all three domains of the protein, apical, intermediate, and equatorial, were necessary. the apical domain alone was able to bind to the l ... | 2008 | 18667427 |
| development of stable isotope and selenomethionine labeling methods for proteins expressed in pseudomonas fluorescens. | pseudomonas fluorescens is a robust protein expression system that is very well suited for high throughput protein expression for structural genomics studies. since nmr spectroscopy and x-ray crystallography are both used by various investigators in structure elucidation studies, the availability of target proteins labeled with stable isotopes or selenomethionine is essential for the determination of protein structures. a completely defined medium for the expression and stable isotope labeling o ... | 2009 | 19166940 |
| liquid culture of the entomogenous nematode steinernema feltiae with its bacterial symbiont. | the insect-parasitic nematode, steinernema feltiae filipjev strain 42, was reared in liquid culture along with its bacterial symbiont, xenorhabdus nematophilus thomas &poinar. first-stage juveniles developed into reproducing adults in a maintenance salts medium containing resuspended xenorhabdus cells and the yeast kluyveromyces marxianus (hansen) van der walt or cholesterol. cultures with media depths greater than 4 mm required aeration. nematode populations increased as bacterial density incre ... | 1989 | 19287644 |
| growth and virulence of steinernema glaseri influenced by different subspecies of xenorhabdus nematophilus. | three xenorhabdus nematophilus subspecies influenced steinernema glaseri growth profiles and growth rates, but this was not necessarily because of different bacterial growth rates. virulence of dauer nematodes in larval galleria mellonella varied with the number of dauers retaining bacteria and the bacterial subspecies. virulence was least for dauers grown on x. nematophilus subsp. bovienii because of the lack of retained bacteria. virulence was subsequently restored by culturing these nematodes ... | 1985 | 19294127 |
| effect of the entomogenous nematode nemplectana carpocapsae on the tachinid parasite compsilura concinnata (diptera: tachinidae). | the entomogenous nematode neoaplectana carpocapsae and its associated bacterium, xenorhabdus nematophilus, could not infect the pupal stage of the tachinid compsilura concinnata through the puparium. n. carpocapsae had an adverse effect on 1-, 2- and 3-day-old c. concinnata larvae within the armyworm host in petri dish tests. all 1-day-old larvae treated with nematodes died in their hosts, whereas 61% and 69% of 2- and 3-day-old larvae treated with nematodes, respectively, died. however, the sur ... | 1984 | 19295866 |
| influence of cell density and phase variants of bacterial symbionts (xenorhabdus spp.) on dauer juvenile recovery and development of biocontrol nematodes steinernema carpocapsae and s. feltiae (nematoda: rhabditida). | the rhabditid nematodes steinernema carpocapsae and steinernema feltiae are used in biological control of insect pests. mass production is done in liquid culture media pre-incubated with their bacterial symbionts xenorhabdus nematophila and xenorhabdus bovienii, respectively, before nematode dauer juveniles (djs) are inoculated. as a response to food signals produced by the bacterial symbionts, the djs exit from the developmentally arrested dauer stage (they recover development) and grow to adul ... | 2009 | 19319521 |
| identification of a new antimicrobial lysine-rich cyclolipopeptide family from xenorhabdus nematophila. | entomopathogenic bacteria of the genus xenorhabdus are known to be symbiotically associated with soil dwelling nematodes of the steinernematidae family. these bacteria are transported by their nematode hosts into the hemocoel of the insect larvae, where they proliferate and produce insecticidal proteins, inhibitors of the insect immune system and antimicrobial molecules. in this study, we describe the discovery of a new family (pax) of five antimicrobial compounds produced by fermentation of the ... | 2009 | 19373275 |
| masters of conquest and pillage: xenorhabdus nematophila global regulators control transitions from virulence to nutrient acquisition. | invertebrate animal models are experimentally tractable and have immunity and disease symptoms that mirror those of vertebrates. therefore they are of particular utility in understanding fundamental aspects of pathogenesis. indeed, artificial models using human pathogens and invertebrate hosts have revealed conserved and novel molecular mechanisms of bacterial infection and host immune responses. additional insights may be gained from investigating interactions between invertebrates and pathogen ... | 2009 | 19374654 |
| cpxra influences xenorhabdus nematophila colonization initiation and outgrowth in steinernema carpocapsae nematodes through regulation of the nil locus. | the gammaproteobacterium xenorhabdus nematophila mutualistically colonizes an intestinal region of a soil-dwelling nematode and is a blood pathogen of insects. the x. nematophila cpxra two-component regulatory system is necessary for both of these host interactions (e. herbert et al., appl. environ. microbiol. 73:7826-7836, 2007). mutualistic association of x. nematophila with its nematode host consists of two stages: initiation, where a small number of bacterial cells establish themselves in th ... | 2009 | 19376901 |
| cpxra contributes to xenorhabdus nematophila virulence through regulation of lrha and modulation of insect immunity. | the gammaproteobacterium xenorhabdus nematophila is a blood pathogen of insects that requires the cpxra signal transduction system for full virulence (e. e. herbert et al., appl. environ. microbiol. 73:7826-7836, 2007). we show here that the deltacpxr1 mutant has altered localization, growth, and immune suppressive activities relative to its wild-type parent during infection of manduca sexta insects. in contrast to wild-type x. nematophila, which were recovered throughout infection, deltacpxr1 c ... | 2009 | 19376911 |
| innate hemocyte responses of malacosoma disstria larvae (c. insecta) to antigens are modulated by intracellular cyclic amp. | invertebrate intracellular hemocyte signaling pathways affecting cellular-antigen responses, although defined for molluscs and some arthropods including dipteran insects, is less known for lepidopterans. hemocytic-antigen responses of the arboreal pest lepidopteran malacosoma disstria are linked to camp-dependent protein kinase a implicating camp in cellular hemocyte immune responses. the purpose in the present study was to determine intracellular camp effects on larval m. disstria hemocytes adh ... | 2009 | 19454331 |
| effect of temperature on the development of steinernema carpocapsae and steinernema feltiae (nematoda: rhabditida) in liquid culture. | for commercial use of the entomopathogenic nematodes steinernema carpocapsae and steinernema feltiae in biological control of insect pests, they are produced in liquid culture on artificial media pre-incubated with their symbiotic bacteria xenorhabdus nematophila and xenorhabdus bovienii, respectively. after 1 day of the bacterial culture, nematode dauer juveniles (djs) are inoculated, which recover development. the adult nematodes produce dj offspring, which are harvested and can be sprayed. th ... | 2009 | 19455323 |
| opns, an outer membrane porin of xenorhabdus nematophila, confers a competitive advantage for growth in the insect host. | the gammaproteobacterium xenorhabdus nematophila engages in a mutualistic association with an entomopathogenic nematode and also functions as a pathogen toward different insect hosts. we studied the role of the growth-phase-regulated outer membrane protein opns in host interactions. opns was shown to be a 16-stranded beta-barrel porin. opns was expressed during growth in insect hemolymph and expression was elevated as the cell density increased. when wild-type and opns deletion strains were coin ... | 2009 | 19465651 |
| isolation and characterization of xenorhabdus nematophila transposon insertion mutants defective in lipase activity against tween. | we identified xenorhabdus nematophila transposon mutants with defects in lipase activity. one of the mutations, in yigl, a conserved gene of unknown function, resulted in attenuated virulence against manduca sexta insects. we discuss possible connections between lipase production, yigl, and specific metabolic pathways. | 2009 | 19542289 |
| influence of inoculum density on population dynamics and dauer juvenile yields in liquid culture of biocontrol nematodes steinernema carpocapsae and s. feltiae (nematoda: rhabditida). | for improvement of mass production of the rhabditid biocontrol nematodes steinernema carpocapsae and steinernema feltiae in monoxenic liquid culture with their bacterial symbionts xenorhabdus nematophila and xenorhabdus bovienii, respectively, the effect of the initial nematode inoculum density on population development and final concentration of dauer juveniles (djs) was investigated. symbiotic bacterial cultures are pre-incubated for 1 day prior to inoculation of djs. djs are developmentally a ... | 2010 | 19597815 |
| a new type of pyrrolidine biosynthesis is involved in the late steps of xenocoumacin production in xenorhabdus nematophila. | | 2009 | 19598185 |
| genetic analysis of xenocoumacin antibiotic production in the mutualistic bacterium xenorhabdus nematophila. | xenocoumacin 1 (xcn1) and xenocoumacin 2 (xcn2) are the major antimicrobial compounds produced by xenorhabdus nematophila. to study the role of xcn1 and xcn2 in the life cycle of x. nematophila the 14 gene cluster (xcna-n) required for their synthesis was identified. overlap rt-pcr analysis identified six major xcn transcripts. individual inactivation of the non-ribosomal peptide synthetase genes, xcna and xcnk, and polyketide synthetase genes, xcnf, xcnh and xcnl, eliminated xcn1 production. xc ... | 2009 | 19682255 |
| characterization of xenorhabdus isolates from la rioja (northern spain) and virulence with and without their symbiotic entomopathogenic nematodes (nematoda: steinernematidae). | eighteen xenorhabdus isolates associated with spanish entomopathogenic nematodes of the genus steinernema were characterized using a polyphasic approach including phenotypic and molecular methods. two isolates were classified as xenorhabdus nematophila and were associated with steinernema carpocapsae. sixteen isolates were classified as xenorhabdus bovienii, of which fifteen were associated with steinernema feltiae and one with steinernema kraussei. two x. bovienii phase ii were also isolated, o ... | 2009 | 19682458 |
| manifold aspects of specificity in a nematode-bacterium mutualism. | coevolution in mutualistic symbiosis can yield, because the interacting partners share common interests, to coadaptation: hosts perform better when associated with symbionts of their own locality than with others coming from more distant places. however, as the two partners of a symbiosis might also experience conflicts over part of their life cycle, coadaptation might not occur for all life-history traits. we investigated this issue in symbiotic systems where nematodes (steinernema) and bacteri ... | 2009 | 19732258 |
| examination of xenorhabdus nematophila lipases in pathogenic and mutualistic host interactions reveals a role for xlpa in nematode progeny production. | xenorhabdus nematophila is a gammaproteobacterium and broad-host-range insect pathogen. it is also a symbiont of steinernema carpocapsae, the nematode vector that transports the bacterium between insect hosts. x. nematophila produces several secreted enzymes, including hemolysins, lipases, and proteases, which are thought to contribute to virulence or nutrient acquisition for the bacterium and its nematode host in vivo. x. nematophila has two lipase activities with distinct in vitro specificitie ... | 2010 | 19880652 |
| regulating alternative lifestyles in entomopathogenic bacteria. | bacteria belonging to the genera photorhabdus and xenorhabdus participate in a trilateral symbiosis in which they enable their nematode hosts to parasitize insect larvae. the bacteria switch from persisting peacefully in a nematode's digestive tract to a lifestyle in which pathways to produce insecticidal toxins, degrading enzymes to digest the insect for consumption, and antibiotics to ward off bacterial and fungal competitors are activated. this study addresses three questions: (1) what molecu ... | 2010 | 20022247 |
| biochemical characteristics of immune-associated phospholipase a(2) and its inhibition by an entomopathogenic bacterium, xenorhabdus nematophila. | an entomopathogenic bacterium, xenorhabdus nematophila, induces an immunosuppression of target insects by inhibiting phospholipase a(2) (pla(2)) activity. recently, an immune-associated pla(2) gene was identified from the red flour beetle, tribolium castaneum. this study cloned this pla(2) gene in a bacterial expression vector to produce a recombinant enzyme. the recombinant t. castaneum pla(2) (tcpla(2)) exhibited its characteristic enzyme activity with substrate concentration, ph, and ambient ... | 2010 | 20127473 |
| a pathogenic parasite interferes with phagocytosis of insect immunocompetent cells. | phagocytosis activity of hemocytes of the host galleria mellonella (lepidoptera) was modulated by the infection of the entomopathogenic nematode steinernema feltiae (rahbditida) and was found to be correlated with the opsonization of bacteria by hemolymph factors. the presence of nematodes resulted in a significative decrease in phagocytosis of bacteria by host hemocytes, both in in vivo and in in vitro assays. host interacting proteins (hips), which appear to function as opsonic factors and are ... | 2010 | 20457179 |
| effects of constant and shifting dissolved oxygen concentration on the growth and antibiotic activity of xenorhabdus nematophila. | to evaluate the effects of dissolved oxygen (do) control strategy on cell growth and the production of antibiotic (cyclo(2-me-baba-gly)) by xenorhabdus nematophila. the effects of different agitation speeds and do concentrations on cell growth and antibiotic activity of x. nematophila yl001 were examined. experiments showed that higher agitation speeds and do concentrations at earlier fermentation stage were favorable for cell growth and antibiotic production. at mid- and later-stage, properly d ... | 2010 | 20488698 |
| imd pathway is involved in the interaction of drosophila melanogaster with the entomopathogenic bacteria, xenorhabdus nematophila and photorhabdus luminescens. | xenorhabdus nematophila/steinernema carpocapsae and photorhabdus luminescens/heterorhabditis bacteriophora are nemato-bacterial complexes highly pathogenic for insects. using a syringe as artificial vector, we have analyzed the effects of the two bacteria, x. nematophila and p. luminescens on the genetic tool insect, drosophila melanogaster. both bacteria were found to kill adult flies in a dose dependent manner with x. nematophila being the fastest. on the other hand, when an injection of non-p ... | 2010 | 20627393 |
| proteolytic enzyme production by strains of the insect pathogen xenorhabdus and characterization of an early-log-phase-secreted protease as a potential virulence factor. | as a comparison to a similar study on photorhabdus strains, 15 xenorhabdus bacterial strains and secondary phenotypic variants of two strains were screened for proteolytic activity by five detection methods. although the number and intensity of proteolytic activities were different, every strain was positive for proteolytic activity by several tests. zymography following native page detected two groups of activities with different substrate affinities and a higher and lower electrophoretic mobil ... | 2010 | 20802071 |
| immunosuppression induced by entomopathogens is rescued by addition of apolipophorin iii in the diamondback moth, plutella xylostella. | apolipophorin iii (apolpiii) has been known to play critical roles in lipid transport and immune activation in insects. this study reports a partial apolpiii gene cloned from the diamondback moth, plutella xylostella. it showed that the gene was expressed in all developmental stages of p. xylostella. in larval stage, it was expressed in all tested tissues of hemocyte, fat body, gut, and epidermis. in response to bacterial challenge, the larvae showed an enhanced level of apolpiii expression by a ... | 2010 | 20937282 |
| benzylideneacetone, an eicosanoid biosynthesis inhibitor enhances baculovirus pathogenicity in the diamondback moth, plutella xylostella. | benzylideneacetone (bza) is a monoterpenoid compound produced by an entomopathogenic bacterium, xenorhabdus nematophila. bza inhibits phospholipase a(2) to suppress biosynthesis of eicosanoids that mediate immune responses in insects. in response to per os infection of autographa californica multiple nucleopolyhedrosis virus (acmnpv), the diamondback moth, plutella xylostella, developed red spots on the midgut epithelium. the midgut exhibiting red spot formation suffered abnormal cell integrity, ... | 2010 | 21112333 |
| virulence and pathogen multiplication: a serial passage experiment in the hypervirulent bacterial insect-pathogen xenorhabdus nematophila. | the trade-off hypothesis proposes that the evolution of pathogens' virulence is shaped by a link between virulence and contagiousness. this link is often assumed to come from the fact that pathogens are contagious only if they can reach high parasitic load in the infected host. in this paper we present an experimental test of the hypothesis that selection on fast replication can affect virulence. in a serial passage experiment, we selected 80 lines of the bacterial insect-pathogen xenorhabdus ne ... | 2011 | 21305003 |
| studies of the dynamic expression of the xenorhabdus fliaz regulon reveal atypical iron-dependent regulation of the flagellin and haemolysin genes during insect infection. | xenorhabdus nematophila engages in complex interactions with invertebrates, through its symbiosis with soil nematodes and its pathogenicity to a broad range of insect larvae. among the regulatory proteins of xenorhabdus involved in host interactions, the sigma factor flia and the regulator fliz, expressed from the fliaz operon, play a key role in mediating the production of exoenzymes, motility and full virulence in insects (lanois et al., 2008). in this study, we investigated the dynamics of th ... | 2011 | 21332625 |
| structure elucidation and biosynthesis of lysine-rich cyclic peptides in xenorhabdus nematophila. | thirteen novel pax (peptide-antimicrobial-xenorhabdus) peptides were identified in xenorhabdus nematophila hgb081. their structures including the absolute configuration were elucidated using a combination of labeling experiments, detailed ms/ms experiments, the advanced marfey's method, and a detailed analysis of the biosynthesis gene cluster, which was identified as well. | 2011 | 21423922 |
| bacterial metabolites of an entomopathogenic bacterium, xenorhabdus nematophila, inhibit a catalytic activity of phenoloxidase of the diamondback moth, plutella xylostella. | a monoterpenoid compound, benzylideneacetone (bza), is identified from bacterial metabolites synthesized by an entomopathogenic bacterium, xenorhabdus nematophila. it inhibits phospholipase a2 of target insects to shut down biosynthesis of various eicosanoids, which play significant roles in insect immunity. this study discovered another novel activity of bza that directly inhibited phenoloxidase (po) activity required for immune-associated melanization. when it was injected into larvae of plute ... | 2011 | 21464604 |
| insecticidal toxin complex proteins from xenorhabdus nematophilus: structure and pore formation. | toxin complexes from xenorhabdus or photorhabdus spp. bacteria represent novel insecticidal proteins. we have purified a native toxin complex (toxin complex 1) from xenorhabdus nematophilus. the toxin complex is composed of three different proteins; xpta2, xptb1, and xptc1 representing products from class a, b and c toxin complex genes, respectively. we show that recombinant xpta2, and co-produced recombinant xptb1 and xptc1 bind together with a 4:1:1 stoichiometry. xpta2 forms a tetramer of ~1, ... | 2011 | 21527640 |
| the xnp1 p2-like tail synthesis gene cluster encodes xenorhabdicin and is required for interspecies competition. | xenorhabdus nematophila, the mutualistic bacterium of the nematode steinernema carpocapsae, produces the r-type bacteriocin called xenorhabdicin that is thought to confer a competitive advantage for growth in the insect host. we have identified a p2-like tail synthesis gene cluster (xnp1) that was required for xenorhabdicin production. the xnp1 genes were expressed constitutively during growth and were induced by mitomycin c. deletion of either the sheath (xnps1) or fiber (xnph1) genes eliminate ... | 2011 | 21602326 |
| manipulation of ph shift to enhance the growth and antibiotic activity of xenorhabdus nematophila. | to evaluate the effects of ph control strategy on cell growth and the production of antibiotic (cyclo(2-me-baba-gly)) by xenorhabdus nematophila and enhance the antibiotic activity. the effects of uncontrolled- (different initial ph) and controlled-ph (different constant ph and ph-shift) operations on cell growth and antibiotic activity of x. nematophila yl00i were examined. experiments showed that the optimal initial ph for cell growth and antibiotic production of x. nematophila yl001 occurred ... | 2011 | 21660139 |
| the entomopathogenic bacterial endosymbionts xenorhabdus and photorhabdus: convergent lifestyles from divergent genomes. | members of the genus xenorhabdus are entomopathogenic bacteria that associate with nematodes. the nematode-bacteria pair infects and kills insects, with both partners contributing to insect pathogenesis and the bacteria providing nutrition to the nematode from available insect-derived nutrients. the nematode provides the bacteria with protection from predators, access to nutrients, and a mechanism of dispersal. members of the bacterial genus photorhabdus also associate with nematodes to kill ins ... | 2011 | 22125637 |
| Phenotypic variation and host interactions of Xenorhabdus bovienii SS-2004, the entomopathogenic symbiont of Steinernema jollieti nematodes. | Xenorhabdus bovienii (SS-2004) bacteria reside in the intestine of the infective-juvenile (IJ) stage of the entomopathogenic nematode, Steinernema jollieti. The recent sequencing of the X. bovienii genome facilitates its use as a model to understand host - symbiont interactions. To provide a biological foundation for such studies, we characterized X. bovienii in vitro and host interaction phenotypes. Within the nematode host X. bovienii was contained within a membrane bound envelope that also en ... | 2011 | 22151385 |
| role of mrx fimbriae of xenorhabdus nematophila in competitive colonization of the nematode host. | xenorhabdus nematophila engages in mutualistic associations with the infective juvenile (ij) stage of specific entomopathogenic nematodes. mannose-resistant (mrx) chaperone-usher-type fimbriae are produced when the bacteria are grown on nutrient broth agar (nb agar). the role of mrx fimbriae in the colonization of the nematode host has remained unresolved. we show that x. nematophila grown on lb agar produced flagella rather than fimbriae. ijs propagated on x. nematophila grown on lb agar were c ... | 2011 | 21856828 |
| cell lines, md108 and md66, from the hemocytes of malacosoma disstria (lepidoptera) display aspects of plasma-free innate non-self activities. | the innate non-self response systems of the deciduous tree pest, the forest tent caterpillar, malacosoma disstria has been documented by us in terms of in vitro and in vivo reactions towards the gram-positive nonpathogenic bacterium, bacillus subtilis and gram-negative pathogenic microbe, xenorhabdus nematophila and their respective surface antigens, lipopoteichoic acids (lta) and lipopolysaccharides (lps). these studies, often conducted in whole and diluted hemolymph, preclude examination of pl ... | 2011 | 21907208 |
| 3d structure of the yersinia entomophaga toxin complex and implications for insecticidal activity. | toxin complex (tc) proteins are a class of bacterial protein toxins that form large, multisubunit complexes. comprising tca, b, and c components, they are of great interest because many exhibit potent insecticidal activity. here we report the structure of a novel tc, yen-tc, isolated from the bacterium yersinia entomophaga mh96, which differs from the majority of bacterially derived tcs in that it exhibits oral activity toward a broad range of insect pests, including the diamondback moth (plutel ... | 2011 | 22158901 |
| Transient expression of a viral histone H4 inhibits expression of cellular and humoral immune-associated genes in Tribolium castaneum. | A viral histone H4 is encoded in a polydnavirus called Cotesia plutellae bracovirus (CpBV), which is symbiotic to an endoparasitoid wasp, C. plutellae. Compared to general histone H4s, the viral H4 possesses an extra N-terminal tail containing 38 amino acid residues, which has been presumed to control host gene expression in an epigenetic mode. To analyze the epigenetic control activity of CpBV-H4 on expression of immune-associated genes, it was transiently expressed in larvae of Tribolium casta ... | 2011 | 22037579 |
| structural analysis of chi1 chitinase from yen-tc: the multisubunit insecticidal abc toxin complex of yersinia entomophaga. | yersinia entomophaga mh96 is a native new zealand soil bacterium that secretes a large abc-type protein toxin complex, yen-tc, similar to those produced by nematode-associated bacteria such as photorhabdus luminescens. y. entomophaga displays an exceptionally virulent pathogenic phenotype in sensitive insect species, causing death within 72 h of infection. because of this phenotype, there is intrinsic interest in the mechanism of action of yen-tc, and it also has the potential to function as a n ... | 2011 | 22108167 |
| Purification, molecular characterization and gene expression analysis of an aspartic protease (Sc-ASP113) from the nematode Steinernema carpocapsae during the parasitic stage. | Steinernema carpocapsae is an insect parasitic nematode associated with the bacterium Xenorhabdus nematophila. During invasion, this nematode is able to express many proteases, including aspartic proteases. Genes encoding these aspartic proteases have been identified in the EST, and aspartic protease has been found in excretory-secretory products. The total protease was shown to digest blood hemoglobin in a zymogram gel. When the protein was partially purified by pepstatin affinity chromatograph ... | 2011 | 22178695 |
| NRPS substrate promiscuity diversifies the xenematides. | Xenematide, a cyclic depsipeptide antibiotic produced by Xenorhabdus nematophila, had a candidate nonribosomal peptide synthetase (NRPS) with atypical features. Differential metabolite analysis between a mutant and wildtype validated that this stand-alone NRPS was required for xenematide production, and further analysis led to a series of new xenematide derivatives encoded by the same NRPS. Our results indicate that adenylation domain promiscuity and relaxed downstream processing in the X. nemat ... | 2011 | 21888371 |
| a natural prodrug activation mechanism in nonribosomal peptide synthesis. | we have identified a new mechanism for the cleavage and activation of nonribosomally made peptides and peptide-polyketide hybrids that are apparently operational in several different bacteria. this process includes the cleavage of a precursor molecule by a membrane-bound and d-asparagine-specific peptidase, as shown here in the biosynthesis of the antibiotic xenocoumacin from xenorhabdus nematophila. | 2011 | 21926994 |
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| the thymus--what's new? | | 2008 | 2661396 |
| nitrous oxide and day-case laparoscopy: effects on nausea, vomiting and return to normal activity. | patients admitted for day-case laparoscopy were assigned randomly to receive nitrous oxide-oxygen or oxygen, with enflurane, during a standard anaesthetic technique. postoperative morbidity, in particular nausea and vomiting, and ability to resume normal activity were assessed over the ensuing 48 h. supplementary administration of propofol during the operative procedure was required significantly more often (p less than 0.05) in the absence of nitrous oxide. there was no significant difference i ... | 2010 | 2967712 |
| improvement in mental depression with decreased thyrotropin response after administration of thyrotropin-releasing hormone. | | 2014 | 4116150 |
| [the topographic anatomical basis for ventriculosinusal shunting in hydrocephalus in nursing and young infants]. | the peculiarities in the structure and topographic anatomical relations of the superior longitudinal, lateral, and sigmoid sinuses were studied on block preparations of the posterior cranial fossa of 14 children under 3 years of age who died from somatic diseases. it was shown that intrasinus inclusions preventing catheterization of the sinus (bands and septa) were absent at the junction of the first angle of the sigmoid sinus with its descending part. the authors recommend this area for shuntin ... | 2007 | 2168650 |
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| method for double-contrast study of the colon. | | 2005 | 1196057 |