| characterization of an extracellular protease from the insect pathogen xenorhabdus luminescens. | xenorhabdus luminescens hm cultured in gelatin broth produced a single extracellular protease. the protease was purified by a factor of 500 and characterized as a monomeric protein with an approximate molecular weight of 61,000. on the basis of inhibitor studies and its ph optimum, the protease was classified as an alkaline metalloprotease with a ph optimum near 8; the isoelectric point of the enzyme is 4.2 +/- 0.2. the protease may be a major factor in the ecology of x. luminescens, which is ca ... | 1988 | 16347777 |
| colonial and cellular polymorphism in xenorhabdus luminescens. | a highly polymorphic xenorhabdus luminescens strain was isolated. the primary form of x. luminescens was luminescent and nonswarming and produced a yellow pigment and antimicrobial substances. the primary form generated a secondary form that had a distinct orange pigmentation, was weakly luminescent, and did not produce antimicrobial substances. both the primary and secondary forms generated a set of colony variants at frequencies that exceeded normal rates for spontaneous mutation. the variant ... | 1989 | 16347906 |
| polyclonal antisera to distinguish strains and form variants of photorhabdus (xenorhabdus) luminescens. | in this study antisera against photorhabdus luminescens strains were prepared for the first time. p. luminescens is a bacterial symbiont of entomopathogenic nematodes belonging to the genus heterorhabditis. to characterize p. luminescens strains and form variants, we produced polyclonal antisera against p. luminescens pe (obtained from nematode strain nlh-e87.3) and against the primary and secondary forms of p. luminescens psh (obtained from nematode strain dh-sh1). in double-diffusion tests all ... | 1995 | 16534911 |
| optical mapping as a routine tool for bacterial genome sequence finishing. | in sequencing the genomes of two xenorhabdus species, we encountered a large number of sequence repeats and assembly anomalies that stalled finishing efforts. this included a stretch of about 12 kb that is over 99.9% identical between the plasmid and chromosome of x. nematophila. | 2007 | 17868451 |
| 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 |
| the insect toxin complex of yersinia. | many members of the yersinia genus encode homologues of insect toxins first observed in bacteria that are insect pathogens such as photorhabdus, xenorhabdus and serratia entomophila. these bacteria secrete high molecular weight insecticidal toxins comprised of multiple protein subunits, termed the toxin complexes or tc's. in photorhabdus three distinct tc subunits are required for full oral toxicity in insects, that include the [a], [b] and [c] types, although the exact stochiometry remains uncl ... | 2007 | 17966421 |
| xenorhabdus antibiotics: a comparative analysis and potential utility for controlling mastitis caused by bacteria. | the role of antibiotics produced by bacterial symbionts of entomopathogenic nematodes is to suppress growth of microbes in the soil environment. these antibiotics are active against gram-positive and gram-negative bacteria, and were tested against mastitis isolates from dairy cows. | 2008 | 17976177 |
| 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 |
| 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 |
| 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 |
| kinetics of infective juvenile production of the entomopathogenic nematode steinernema carpocapsae in submerged monoxenic culture. | the effects of culture medium formulations on the kinetics of infective juvenile (ij) production of the entomopathogenic nematode steinernema carpocapsae in submerged monoxenic culture, were studied at the cylindrical-bottle scale using six culture media containing agave juice from agave spp. among other ingredients. the ij production kinetics was well modelled through a re-parameterised 3-parameter gompertz model with kinetic parameters: ij-lag phase lambda (ij) (day), maximum ij-stage producti ... | 2008 | 18074155 |
| 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 |
| 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 |
| steinernema feltiae: ammonia triggers the emergence of their infective juveniles. | entomopathogenic nematodes complete their life cycles inside dead insects. the emergence of new infective juveniles from the cadaver has been attributed (but never demonstrated) to food depletion or to the accumulation of metabolites from the breakdown of the host's tissues. here we give evidence that emergence is triggered by ammonia, a product of nematode defecation. we found that the emergence of steinernemafeltiae infective juveniles from galleriamellonella cadavers was stimulated by a parti ... | 2008 | 18316080 |
| 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 |
| pathogenic effect of entomopathogenic nematode-bacterium complexes on terrestrial isopods. | in this study, we evaluated the effect of entomopathogenic nematodes (epns) steinernema carpocapsae, steinernema feltiae and heterorhabditis bacteriophora, symbiotically associated with bacteria of the genera xenorhabdus or photorhabdus, on the survival of eight terrestrial isopod species. the epn species s. carpocapsae and h. bacteriophora reduced the survival of six isopod species while s. feltiae reduced survival for two species. two terrestrial isopod species tested (armadillidium vulgare an ... | 2008 | 18346756 |
| steinernema sichuanense n. sp. (rhabditida, steinernematidae), a new species of entomopathogenic nematode from the province of sichuan, east tibetan mts., china. | steinernema sichuanense n. sp. is characterized by male, female and ij. for male, the spicules are robust with prominent rostrum; gubernaculum has blunt anterior end; cuneus is arrow-shaped, pointed posteriorly. second-generation male has a prominent mucron. for female, tail usually has one to four papillae-like projections on tail tip; post anal swelling is absent. for ij, body length is about 710 microm; lateral field has six ridges; the formula of lateral field is 2, 5, 6, 4, 2 with two promi ... | 2006 | 16934830 |
| 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 |
| 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 |
| protein kinase a affects galleria mellonella (insecta: lepidoptera) larval haemocyte non-self responses. | we used the protein kinase a (pka) specific activator sp-8-br-camps and type i inhibitor rp-8-br-camps alone and in combination to define the role of pka in the non-self responses of larval galleria mellonella haemocytes in vitro and in vivo. active pka depressed haemocyte responses whereas pka inhibition enhanced activities, including bacterial phagocytosis, the number of haemocytes with adherent bacteria, bacterial-induced haemocytic protein release and haemocyte adhesion to slides in vitro, a ... | 2005 | 15748211 |
| 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. | 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 |
| 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 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 |
| a novel species of xenorhabdus, family enterobacteriaceae: xenorhabdus indica sp. nov., symbiotically associated with entomopathogenic nematode steinernema thermophilum ganguly and singh, 2000. | in the search for novel xenorhabdus strains in a recently described nematode species, steinernema thermophilum, three strains (strain 28(t) = dsm 17382(t), strain 42 = dsm 17383 and strain 43 = dsm 17384) were isolated from three independent isolation approaches from crushed mixture of infective juveniles. 16s rrna gene sequence comparison of strains 28(t) and dsm 17383 indicated identity and the phylogenetic position pointed towards an individual taxon within the phylogenetic dendrogram of xeno ... | 2006 | 16459045 |
| 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 |
| [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 |
| responses of the entomopathogenic nematode, steinernema riobrave to its insect hosts, galleria mellonella and tenebrio molitor. | potential hosts for infective juveniles of entomopathogenic nematodes can vary considerably in quality based on the characteristics of the host species/stage, physiological status (e.g. stress, feeding on toxins), and infection status (heterospecific or conspecific infection). in this study, we investigated responses of the entomopathogenic nematode steinernema riobrave to hosts (galleria mellonella or tenebrio molitor) that were previously parasitized with conspecifics or injected with the nema ... | 2007 | 17201992 |
| insecticidal toxins from photorhabdus bacteria and their potential use in agriculture. | most of the insecticidal toxins used in agriculture come from a single bacterium bacillus thuringiensis or 'bt'. here we review our work on the array of toxins produced by photorhabdus and xenorhabdus bacteria that are symbiotic with entomopathogenic nematodes, and discuss their potential for use in agriculture as alternatives to bt. despite the fact that both photorhabdus and xenorhabdus are introduced directly into the insect blood stream by their nematode vectors, they produce a range of toxi ... | 2007 | 17207509 |
| 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 |
| 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 |
| 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 |
| mutualism and pathogenesis in xenorhabdus and photorhabdus: two roads to the same destination. | photorhabdus and xenorhabdus bacteria colonize the intestines of the infective soil-dwelling stage of entomophagous nematodes, heterorhabditis and steinernema, respectively. these nematodes infect susceptible insect larvae and release the bacteria into the insect blood. the bacteria kill the insect larvae and convert the cadaver into a food source suitable for nematode growth and development. after several rounds of reproduction the nematodes are recolonized by the bacteria before emerging from ... | 2007 | 17493120 |
| isolation and activity of xenorhabdus antimicrobial compounds against the plant pathogens erwinia amylovora and phytophthora nicotianae. | broad-spectrum antibiotics produced by symbiotic bacteria [entomopathogenic bacterium (epb)] of entomopathogenic nematodes keep monoxenic conditions in insect cadavers in soil. this study evaluated antibiotics produced by epb for their potential to control plant pathogenic bacteria and oomycetes. | 2009 | 19320949 |
| entomopathogenic bacteria as a source of secondary metabolites. | insects are not only the most diverse group of animals on our planet, but also a huge reservoir for unusual microorganism which are a rich source of pharmaceutically interesting natural products. this review focuses on recent advances in the understanding of secondary metabolism of bacillus thuringiensis, pseudomonas entomophila, and xenorhabdus and photorhabdus bacteria all of which are entomopathogenic. genome-sequencing projects revealed the capacity of these bacteria to produce several diffe ... | 2009 | 19345136 |
| 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 |
| bioluminescent salmonella reverse mutation assay: a screen for detecting mutagenicity with high throughput attributes. | here, we describe the development and evaluation of a novel bioluminescent high-throughput salmonella reverse mutation assay applicable to the screening of large numbers of small molecules. the bioluminescent salmonella assay utilizes genetically engineered standard salmonella tester strains ta98 and ta100 expressing the lux(cdabe) operon from xenorhabdus luminescence. in principle, the assay employs bioluminescence as a sensor of changes in bacterial metabolism associated with starvation or ene ... | 2007 | 17656636 |
| critical role of glu175 on stability and folding of bacterial luciferase: stopped-flow fluorescence study. | bacterial luciferase is a heterodimeric enzyme, which catalyzes the light emission reaction, utilizing reduced fmn (fmnh2), a long chain aliphatic aldehyde and o(2), to produce green-blue light. this enzyme can be readily classed as slow or fast decay based on their rate of luminescence decay in a single turnover. mutation of glu175 in alpha subunit to gly converted slow decay xenorhabdus luminescence luciferase to fast decay one. the following studies revealed that changing the luciferase flexi ... | 2007 | 17669259 |
| 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 |
| 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 |
| temperature effects on korean entomopathogenic nematodes, steinernema glaseri and s. longicaudum, and their symbiotic bacteria. | we investigated the temperature effects on the virulence, development, reproduction, and motility of two korean isolates of entomopathogenic nematodes, steinernema glaseri dongrae strain and s. longicaudum nonsan strain. in addition, we studied the growth and virulence of their respective symbiotic bacterium, xenorhabdus poinarii for s. glaseri and xenorhabdus sp. for s. longicaudum, in an insect host at different temperatures. insects infected with the nematode-bacterium complex or the symbioti ... | 2007 | 18050945 |
| 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 |
| comparative genomics of the emerging human pathogen photorhabdus asymbiotica with the insect pathogen photorhabdus luminescens. | the gram-negative bacterium photorhabdus asymbiotica (pa) has been recovered from human infections in both north america and australia. recently, pa has been shown to have a nematode vector that can also infect insects, like its sister species the insect pathogen p. luminescens (pl). to understand the relationship between pathogenicity to insects and humans in photorhabdus we have sequenced the complete genome of pa strain atcc43949 from north america. this strain (formerly referred to as xenorh ... | 2009 | 19583835 |
| new insight into diversity in the genus xenorhabdus, including the description of ten novel species. | we investigated the diversity of a collection of 76 xenorhabdus strains, isolated from at least 27 species of steinernema nematodes and collected in 32 countries, using three complementary approaches: 16s rrna gene sequencing, molecular typing and phenotypic characterization. the 16s rrna gene sequences of the xenorhabdus strains were highly conserved (similarity coefficient >95 %), suggesting that the common ancestor of the genus probably emerged between 250 and 500 million years ago. based on ... | 2006 | 17158981 |
| a new type of pyrrolidine biosynthesis is involved in the late steps of xenocoumacin production in xenorhabdus nematophila. | | 2009 | 19598185 |
| group selection on population size affects life-history patterns in the entomopathogenic nematode steinernema carpocapsae. | selection is recognized to operate on multiple levels. in disease organisms, selection among hosts is thought to provide an important counterbalance to selection for faster growth within hosts. we performed three experiments, each selecting for a divergence in group size in the entomopathogenic nematode, steinernema carpocapsae. these nematodes infect and kill insect larvae, reproduce inside the host carcass, and emerge as infective juveniles. we imposed selection on group size by selecting amon ... | 2009 | 19187254 |
| entomopathogenic nematodes and bacteria applications for control of the pecan root-knot nematode, meloidogyne partityla, in the greenhouse. | meloidogyne partityla is a parasite of pecan and walnut. our objective was to determine interactions between the entomopathogenic nematode-bacterium complex and m. partityla. specifically, we investigated suppressive effects of steinernema feltiae (strain sn) and s. riobrave (strain 7-12) applied as infective juveniles and in infected host insects, as well as application of s. feltiae's bacterial symbiont xenorhabdus bovienii on m. partityla. in two separate greenhouse trials, the treatments wer ... | 2006 | 19259462 |
| 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 |
| 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 |
| spiteful interactions in a natural population of the bacterium xenorhabdus bovienii. | an individual behaves spitefully when it harms itself in the act of harming other individuals. one of the clearest potential examples of spite is the costly production and release of toxins called bacteriocins. bacteriocins are toxins produced by bacteria that can kill closely related strains of the same species. theoretical work has predicted that bacteriocin-mediated interactions could play an important role in maintaining local genetic and/or species diversity, but these interactions have not ... | 2010 | 20095826 |
| a survival-reproduction trade-off in entomopathogenic nematodes mediated by their bacterial symbionts. | in this work, we investigate the investment of entomopathogenic steinernema nematodes (rhabditidae) in their symbiotic association with xenorhabdus bacteria (enterobacteriaceae). their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (ijs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new ijs occur. previou ... | 2008 | 18194474 |
| 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 |
| host-pathogen interactions: proline gives insect pathogens the green light. | how does a quiescent symbiont of a nematode worm know when to turn nasty? metabolic analysis and genetic knockouts confirm that model insect pathogens can sense l-proline in insect blood. this not only serves as a wake-up call, activating secondary metabolite virulence factors, but also provides an energy source for a metabolic shift appropriate for adaptation to the host environment. | 2010 | 20152135 |
| 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 |
| isolation and identification of entomopathogenic nematodes and their symbiotic bacteria from hérault and gard (southern france). | isolation and identification of native nematode-bacterial associations in the field are necessary for successful control of endemic pests in a particular location. no study has yet been undertaken to recover and identify epn in metropolitan france. in the present paper, we provide results of a survey of epn and their symbiotic bacteria conducted in hérault and gard regions in southern france. molecular characterization of isolated nematodes depicted three different steinernema species and one he ... | 2008 | 18353356 |
| the evolution of spite: population structure and bacteriocin-mediated antagonism in two natural populations of xenorhabdus bacteria. | spite occurs when an individual harms itself in the act of harming other individuals. such behaviors were once assumed to be of limited evolutionary importance, as the conditions for the evolution of spite were thought to be too restrictive. recent theoretical work, however, suggests that spatial population structure, which allows local competition among genotypes, could favor the evolution of spite. one of the clearest examples of spite is the costly production and release by bacteria of toxins ... | 2010 | 20584073 |
| 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 |
| 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 |
| a multilocus approach to assessing co-evolutionary relationships between steinernema spp. (nematoda: steinernematidae) and their bacterial symbionts xenorhabdus spp. (gamma-proteobacteria: enterobacteriaceae). | nematodes of the genus steinernema travassos, 1927 (nematoda: steinernematidae) and their associated bacteria, xenorhabdus spp. (gamma-proteobacteria), are an emergent model of terrestrial animal-microbe symbiosis. interest in this association initially arose out of their potential as biocontrol agents against insect pests, but, despite advances in their field application and the growing popularity of this model system, relatively little has been published to uncover the evolutionary facets of t ... | 2010 | 20700692 |
| 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 |
| 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 |
| units of plasticity in bacterial genomes: new insight from the comparative genomics of two bacteria interacting with invertebrates, photorhabdus and xenorhabdus. | flexible genomes facilitate bacterial evolution and are classically organized into polymorphic strain-specific segments called regions of genomic plasticity (rgps). using a new web tool, rgpfinder, we investigated plasticity units in bacterial genomes, by exhaustive description of the rgps in two photorhabdus and two xenorhabdus strains, belonging to the enterobacteriaceae and interacting with invertebrates (insects and nematodes). | 2010 | 20950463 |
| 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 |
| horse species symposium: a novel approach to monitoring pathogen progression during uterine and placental infection in the mare using bioluminescence imaging technology and lux-modified bacteria. | uterine and placental infections are the leading cause of abortion, stillbirth, and preterm delivery in the mare. whereas uterine and placental infections in women have been studied extensively, a comprehensive examination of the pathogenic processes leading to this unsatisfactory pregnancy outcome in the mare has yet to be completed. most information in the literature relating to late-term pregnancy loss in mares is based on retrospective studies of clinical cases submitted for necropsy. here w ... | 2011 | 21239661 |
| the first record of entomopathogenic nematodes (rhabiditiae: steinernematidae and heterorhabditidae) in natural ecosystems in lebanon: a biogeographic approach in the mediterranean region. | a survey of entomopathogenic nematodes in lebanon was conducted for the first time during 2008-2009. samples were collected on the coastal strip and in nine vegetation types extending from the coastal line to 3088m above sea level. wooded and herbaceous ecosystems were considered for sampling purposes. a total of 570 samples were taken, out of which 1% were positive for entomopathogenic nematodes. approximately, 15.8% out of the 19 sites sampled revealed entomopathogenic nematodes presence (repr ... | 2011 | 21241704 |
| the bacterium associated with the entomopathogenic nematode steinernema abbasi (nematoda: steinernematidae) isolated from taiwan. | a symbiotic bacterium of the entomopathogenic nematode, steinernema abbasi, isolated from taiwan, determined to be a species of xenorhabdus based on its physiological and biochemical characteristics has been determined to be similar to xenorhabdus indica of s. abbasi oman isolate as based on sequence analyses of 16s rdna. | 2008 | 18486948 |
| 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 |
| 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 |
| 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 |
| role of symbiotic and non-symbiotic bacteria in carbon dioxide production from hosts infected with steinernema riobrave. | entomopathogenic nematodes of the family steinernematidae and their mutualistic bacteria (xenorhabdus spp.) are lethal endoparasites of insects. we hypothesized that growth of the nematode's mutualistic bacteria in the insect host may contribute to the production of cues used by the infective juveniles (ijs) in responding to potential hosts for infection. specifically, we tested if patterns of bacterial growth could explain differences in co2 production over the course of host infection. growth ... | 2008 | 18621386 |
| in vitro and in vivo antimicrobial activity of xenorhabdus bovienii yl002 against phytophthora capsici and botrytis cinerea. | aims: developing new bio-agents to control plant disease is desirable. entomopathogenic bacteria xenorhabdus spp. have potential antimicrobial activity in agriculture. this work was conducted to evaluate the antimicrobial activity of xenorhabdus bovienii yl002 on plant pathogenic fungi and oomycete in vitro and the efficiency of this strain to reduce the in vivo incidence of grey mould rot on tomato plants caused by botrytis cinerea and leaf scorch on pepper plants caused by phytophthora capsic ... | 2011 | 21554568 |
| 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 |
| 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 |
| 16s rdna-based phylogeny of non-symbiotic bacteria of entorno-pathogenic nematodes from infected insect cadavers. | using 16s rdna gene sequencing technique, three different species of non-symbiotic bacteria of entomopatho-genic nematodes (epns) (steinernema sp. and heterorhabditis sp.) were isolated and identified from infected insect cadavers {galleria mellonella larvae) after 48-hour post infections. sequence similarity analysis revealed that the strains srk3, srk4 and srk5 belong to ochrobactrum cytisi, schineria larvae and ochrobactrum anthropi, respectively. the isolates o. anthropi and s. larvae were f ... | 2011 | 21802047 |
| 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 |
| comparative in vivo gene expression of the closely related bacteria photorhabdus temperata and xenorhabdus koppenhoeferi upon infection of the same insect host, rhizotrogus majalis. | photorhabdus and xenorhabdus are gram-negative, phylogenetically related, enterobacteria, forming mutualism with the entomopathogenic nematodes heterorhabditis and steinernema, respectively. the mutualistic bacteria living in the intestines of the nematode infective juveniles are pathogenic to the insect upon release by the nematodes into the insect hemolymph. such a switch needs activation of genes that promote bacterial virulence. we studied in vivo gene expression in photorhabdus temperata an ... | 2009 | 19754939 |
| phylogeny of photorhabdus and xenorhabdus based on universally conserved protein-coding sequences and implications for the taxonomy of these two genera. proposal of new taxa: x. vietnamensis sp. nov., p. luminescens subsp. caribbeanensis subsp. nov., p. luminescens subsp. hainanensis subsp. nov., p. temperata subsp. khanii subsp. nov., p. temperata subsp. tasmaniensis subsp. nov., and the reclassification of p. luminescens subsp. thracensis as p. temperata subsp. thracensis comb. nov. | we used the information from a set of concatenated sequences from four genes (reca, gyrb, dnan and gltx) to investigate the phylogeny of the genera photorhabdus and xenorhabdus (entomopathogenic bacteria associated with nematodes of the genera heterorhabditis and steinernema, respectively). the robustness of the phylogenetic tree obtained by this multigene approach was significantly better than that of the tree obtained by a single gene approach. the comparison of the topologies of single gene p ... | 2010 | 19783607 |
| 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 |
| 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 |
| 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 |
| a multigene approach for assessing evolutionary relationships of xenorhabdus spp. (gamma-proteobacteria), the bacterial symbionts of entomopathogenic steinernema nematodes. | xenorhabdus spp., are gram-negative bacterial symbionts of entomopathogenic nematodes in the genus steinernema. a specialized and intimate relationship exists between nematode and bacteria, affecting many of their life history traits, such as nutrition, dispersal, host-finding, foraging and defense from biotic and abiotic factors. xenorhabdus currently comprises more than 20 species isolated from steinernema spp. with diverse host range, host foraging behavior, reproductive modes and environment ... | 2010 | 20102721 |
| 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 |
| 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 |
| 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 |
| Description of Xenorhabdus magdalenensis sp. nov., the symbiotic bacterium associated with Steinernema australe. | The symbiotic bacterium (IMI 397775T, DSM 24915T) was isolated from the insect-pathogenic nematode Steinernema australe. On the basis of 16S rRNA gene sequence similarity, this bacterial isolate was shown to belong to the genus Xenorhabdus in agreement with the genus of its nematode-host. The accurate phylogenetic position of this new isolate was defined using a multigene approach and showed that isolate IMI 397775T shares a common ancestor with X. doucetiae FRM16 T and X. romanii PR06-AT, the s ... | 2011 | 21948091 |
| Detection and Identification of Species-Specific Bacteria Associated with Synanthropic Mites. | Internal bacterial communities of synanthropic mites Acarus siro, Dermatophagoides farinae, Lepidoglyphus destructor, and Tyrophagus putrescentiae (Acari: Astigmata) were analyzed by culturing and culture-independent approaches from specimens obtained from laboratory colonies. Homogenates of surface-sterilized mites were used for cultivation on non-selective agar and DNA extraction. Isolated bacteria were identified by sequencing of the 16S rRNA gene. PCR amplified 16S rRNA genes were analyzed b ... | 2011 | 22057398 |