scholarly journals Early Colonization Events in the Mutualistic Association between Steinernema carpocapsae Nematodes and Xenorhabdus nematophila Bacteria

2003 ◽  
Vol 185 (10) ◽  
pp. 3147-3154 ◽  
Author(s):  
Eric C. Martens ◽  
Kurt Heungens ◽  
Heidi Goodrich-Blair
Keyword(s):  
Fluorescent Protein ◽  
Ex Vivo ◽  
Entomopathogenic Nematode ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Bacterial Cells ◽  
Biological Interactions ◽  
Xenorhabdus Nematophila ◽  
Molecular Events ◽  
Final Population

ABSTRACT The bacterium Xenorhabdus nematophila is a mutualist of the entomopathogenic nematode Steinernema carpocapsae. During its life cycle, the bacterium exists both separately from the nematode and as an intestinal resident of a nonfeeding nematode form, the infective juvenile (IJ). The progression of X. nematophila from an ex vivo existence to a specific and persistent colonization of IJs is a model to understand the mechanisms mediating the initiation and maintenance of benign host-microbe interactions. To help characterize this process, we constructed an X. nematophila strain that constitutively expresses green fluorescent protein, which allowed its presence to be monitored within IJs. Using this strain, we showed that few bacterial cells initiate colonization of an individual IJ and that these grow inside the lumen of the IJ intestine in a reproducible polyphasic pattern during colonization. In accordance with these two observations, we demonstrated that the final population of bacteria in a nematode is of predominantly monoclonal origin, suggesting that only one or two bacterial clones initiate or persist during colonization of an individual nematode. These data suggest that X. nematophila initiates IJ colonization by competing for limited colonization sites or resources within the nematode intestine. This report represents the first description of the biological interactions occurring between X. nematophila and S. carpocapsae during the early stages of the colonization process, provides insights into the physiology of X. nematophila in its host niche, and will facilitate interpretation of future data regarding the molecular events mediating this process.

scholarly journals 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

2007 ◽  
Vol 73 (16) ◽  
pp. 5338-5346 ◽  
Author(s):  
Holly Snyder ◽  
S. Patricia Stock ◽  
Sam-Kyu Kim ◽  
Yolanda Flores-Lara ◽  
Steven Forst
Keyword(s):  
Fluorescent Protein ◽  
Distal Region ◽  
Steinernema Carpocapsae ◽  
Intestinal Lumen ◽  
Infective Juvenile ◽  
Bacterial Cells ◽  
Xenorhabdus Nematophila ◽  
Forward Movement ◽  
Release Process ◽  
Green Fluorescent

ABSTRACT 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 fluorescent protein-labeled bacteria during the release process. Our observations revealed that Xenorhabdus colonizes the distal region of the receptacle and that exposure to insect hemolymph stimulated forward movement of the bacteria to the esophagointestinal junction. Continued exposure to hemolymph caused a narrow passage in the distal receptacle to widen, allowing movement of Xenorhabdus down the intestine and out the anus. Efficient release of both the wild type and a nonmotile strain was evident in most of the IJs incubated in hemolymph, whereas only a few IJs incubated in nutrient-rich broth released bacterial cells. Incubation of IJs in hemolymph treated with agents that induce nematode paralysis dramatically inhibited the release process. These results suggest that bacterial motility is not required for movement out of the distal region of the receptacle and that hemolymph-induced esophageal pumping provides a force for the release of X. nematophila out of the receptacle and into the intestinal lumen.

scholarly journals Stages of Infection during the Tripartite Interaction between Xenorhabdus nematophila, Its Nematode Vector, and Insect Hosts

2004 ◽  
Vol 70 (11) ◽  
pp. 6473-6480 ◽  
Author(s):  
Mathieu Sicard ◽  
Karine Brugirard-Ricaud ◽  
Sylvie Pag�s ◽  
Anne Lanois ◽  
Noel E. Boemare ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Spodoptera Littoralis ◽  
Fluorescent Protein ◽  
Bacterial Colonization ◽  
Infective Juvenile ◽  
Bacterial Cells ◽  
Xenorhabdus Nematophila ◽  
Insect Larvae ◽  
Connective Tissues ◽  
Anterior Midgut

ABSTRACT Bacteria of the genus Xenorhabdus are mutually associated with entomopathogenic nematodes of the genus Steinernema and are pathogenic to a broad spectrum of insects. The nematodes act as vectors, transmitting the bacteria to insect larvae, which die within a few days of infection. We characterized the early stages of bacterial infection in the insects by constructing a constitutive green fluorescent protein (GFP)-labeled Xenorhabdus nematophila strain. We injected the GFP-labeled bacteria into insects and monitored infection. We found that the bacteria had an extracellular life cycle in the hemolymph and rapidly colonized the anterior midgut region in Spodoptera littoralis larvae. Electron microscopy showed that the bacteria occupied the extracellular matrix of connective tissues within the muscle layers of the Spodoptera midgut. We confirmed the existence of such a specific infection site in the natural route of infection by infesting Spodoptera littoralis larvae with nematodes harboring GFP-labeled Xenorhabdus. When the infective juvenile (IJ) nematodes reached the insect gut, the bacterial cells were rapidly released from the intestinal vesicle into the nematode intestine. Xenorhabdus began to escape from the anus of the nematodes when IJs were wedged in the insect intestinal wall toward the insect hemolymph. Following their release into the insect hemocoel, GFP-labeled bacteria were found only in the anterior midgut region and hemolymph of Spodoptera larvae. Comparative infection assays conducted with another insect, Locusta migratoria, also showed early bacterial colonization of connective tissues. This work shows that the extracellular matrix acts as a particular colonization site for X. nematophila within insects.

scholarly journals Studying the Symbiotic Bacterium Xenorhabdus nematophila in Individual, Living Steinernema carpocapsae Nematodes Using Microfluidic Systems

mSphere ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Matthew D. Stilwell ◽  
Mengyi Cao ◽  
Heidi Goodrich-Blair ◽  
Douglas B. Weibel
Keyword(s):  
Entomopathogenic Nematode ◽  
Experimental System ◽  
Symbiotic Bacterium ◽  
Lessons Learned ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Xenorhabdus Nematophila ◽  
Bacterial Populations ◽  
Individual Host ◽  
Host Microbe Interactions

This paper describes an experimental system for directly investigating population dynamics of a symbiotic bacterium,Xenorhabdus nematophila, in its host—the infective stage of the entomopathogenic nematodeSteinernema carpocapsae. Tracking individual and groups of bacteria in individual host nematodes over days and weeks yielded insight into dynamic growth and topology changes of symbiotic bacterial populations within infective juvenile nematodes. Our approach for studying symbioses between bacteria and nematodes provides a system to investigate long-term host-microbe interactions in individual nematodes and extrapolate the lessons learned to other bacterium-animal interactions.

scholarly journals Transcriptional variation and divergence of host-finding behaviour in Steinernema carpocapsae infective juveniles

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Neil D. Warnock ◽  
Deborah Cox ◽  
Ciaran McCoy ◽  
Robert Morris ◽  
Johnathan J. Dalzell
Keyword(s):  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Gene Families ◽  
Nematode Species ◽  
Host Finding ◽  
Steinernema Carpocapsae ◽  
Differentially Expressed ◽  
Infective Juvenile ◽  
Neuronal Genes ◽  
Sodium Transporter

Abstract Background Steinernema carpocapsae is an entomopathogenic nematode that employs nictation and jumping behaviours to find potential insect hosts. Here we aimed to investigate the transcriptional basis of variant host-finding behaviours in the infective juvenile (IJ) stage of three S. carpocapsae strains (ALL, Breton and UK1), with a focus on neuronal genes known to influence behaviour in other nematode species. Identifying gene expression changes that correlate with variant host-finding behaviours will further our understanding of nematode biology. Results RNA-seq analysis revealed that whilst up to 28% of the S. carpocapsae transcriptome was differentially expressed (P < 0.0001) between strains, remarkably few of the most highly differentially expressed genes (> 2 log2 fold change, P < 0.0001) were from neuronal gene families. S. carpocapsae Breton displays increased chemotaxis toward the laboratory host Galleria mellonella, relative to the other strains. This correlates with the up-regulation of four srsx chemosensory GPCR genes, and a sodium transporter gene, asic-2, relative to both ALL and UK1 strains. The UK1 strain exhibits a decreased nictation phenotype relative to ALL and Breton strains, which correlates with co-ordinate up-regulation of neuropeptide like protein 36 (nlp-36), and down-regulation of an srt family GPCR gene, and a distinct asic-2-like sodium channel paralogue. To further investigate the link between transcriptional regulation and behavioural variation, we sequenced microRNAs across IJs of each strain. We have identified 283 high confidence microRNA genes, yielding 321 predicted mature microRNAs in S. carpocapsae, and find that up to 36% of microRNAs are differentially expressed (P < 0.0001) between strains. Many of the most highly differentially expressed microRNAs (> 2 log2 fold, P < 0.0001) are predicted to regulate a variety of neuronal genes that may contribute to variant host-finding behaviours. We have also found evidence for differential gene isoform usage between strains, which alters predicted microRNA interactions, and could contribute to the diversification of behaviour. Conclusions These data provide insight to the transcriptional basis of behavioural variation in S. carpocapsae, supporting efforts to understand the molecular basis of complex behaviours in nematodes.

scholarly journals Spodoptera frugiperda transcriptional response to infestation by Steinernema carpocapsae

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Louise Huot ◽  
Simon George ◽  
Pierre-Alain Girard ◽  
Dany Severac ◽  
Nicolas Nègre ◽  
...  
Keyword(s):  
Spodoptera Frugiperda ◽  
Fat Body ◽  
Entomopathogenic Nematode ◽  
Transcriptional Response ◽  
Early Time ◽  
Symbiotic Bacterium ◽  
Steinernema Carpocapsae ◽  
Differentially Expressed ◽  
Xenorhabdus Nematophila ◽  
Transcriptional Responses

Abstract Steinernema carpocapsae is an entomopathogenic nematode (EPN) used in biological control of agricultural pest insects. It enters the hemocoel of its host via the intestinal tract and releases its symbiotic bacterium Xenorhabdus nematophila. In order to improve our knowledge about the physiological responses of its different hosts, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest Spodoptera frugiperda. The tissues poorly respond to the infestation at an early time post-infestation of 8 h with only 5 genes differentially expressed in the fat body of the caterpillars. Strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. Few genes are differentially expressed in the midgut but tissue-specific panels of induced metalloprotease inhibitors, immune receptors and antimicrobial peptides together with several uncharacterized genes are up-regulated in the fat body and the hemocytes. Among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, which show homology with bacterial genes of unknown function. Altogether, these results pave the way for further functional studies of the responsive genes’ involvement in the interaction with the EPN.

Mechanisms of specificity of association between the nematode Steinernema scapterisci and its symbiotic bacterium

Parasitology ◽  
1997 ◽  
Vol 114 (5) ◽  
pp. 483-488 ◽  
Author(s):  
P. S. GREWAL ◽  
M. MATSUURA ◽  
V. CONVERSE
Keyword(s):  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Symbiotic Bacterium ◽  
Bacterial Symbiont ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Symbiotic Bacteria ◽  
Bacterial Symbionts ◽  
First Report ◽  
Successful Isolation

We suggest a new mechanism for the maintenance of specificity of the association between the entomopathogenic nematode Steinernema scapterisci and its symbiotic bacteria. We evaluated the development and reproduction of infective and non-infective juvenile S. scapterisci in monoxenic combinations with its symbiotic bacteria, Xenorhabdus sp. ‘S’ and with the bacterial symbiont of Steinernema carpocapsae and Steinernema riobravis. Although development of non-infective stages occurred on all Xenorhabdus spp., the development of infective juveniles to the 4th stage (‘dauer’ recovery) was significantly delayed and reduced with X. nematophilus and Xenorhabdus sp. ‘R’, the bacterial symbionts of S. carpocapsae and S. riobravis, respectively. ‘Dauer’ recovery improved significantly when the cultures of X. nematophilus and Xenorhabdus sp. ‘R’ were supplemented with cell-free filtrates from Xenorhabdus sp. ‘S’. The infective juvenile S. scapterisci produced in all 3 cultures were virulent to Galleria mellonella larvae, confirming successful retention of Xenorhabdus from other steinernematids in their intestine. In fact, S. scapterisci infective juveniles containing X. nematophilus or Xenorhabdus sp. ‘R’ were more virulent to G. mellonella than those containing their natural symbiont, Xenorhabdus sp. ‘S’. We believe that this is the first demonstration of the symbiont-specific exit of infective juveniles from the ‘dauer’ phase which represents the finest level of specificity of bacteria–nematode association. This is also the first report of successful isolation of the natural symbiont of S. scapterisci.

scholarly journals Mass production of the entomopathogenic nematode, Steinernema carpocapsae on Tenebrio molitor and Spodoptera litura

2019 ◽  
Vol 20 (5) ◽  
Author(s):  
HERI PRABOWO ◽  
SRI ADIKADARSIH ◽  
JANIS DAMAIYANI
Keyword(s):  
Body Length ◽  
Mass Production ◽  
Spodoptera Litura ◽  
Entomopathogenic Nematode ◽  
Total Yield ◽  
Tenebrio Molitor ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Small Farm

Abstract. Authors. 2019. Mass production of the entomopathogenic nematode, Steinernema carpocapsae on Tenebrio Molitor and Spodoptera litura. Biodiversitas 20: 1344-1349. Steinernema carpocapsae is the most developed biological agents to control pests nowadays, to support this nematode as a biological agent mass production technique is required. S. carpocapsae can be produced via in vivo methods. In vivo production has some advantages, such as cheap, easy, and sustainable to be developed in small farm agriculture. The purpose of this research was to evaluate the mass production of S. carpocapsae using Tenebrio molitor and Spodoptera litura larvae as hosts. Twenty-five last instar larvae were inoculated with different concentrations of infective juvenile (IJ) (e.g., 100, 200, 300 and 400 IJ/larvae) of S. carpocapsae Asembagus. The production of S. carpocapsae with concentrations of 100, 200, 300 and 400 IJ/larvae on T. molitor and S. litura showed 3.62x103; 6.29x103; 1.13x104; 1.52x104; 1.13x104; 1.46x104; 1.54x104; and 1.94x104 IJ/larvae, respectively. The IJ harvest from T. molitor and S. litura shows the longest body length for IJ at a concentration of 400 IJ/larva of 437.48µm and 591.42µm, respectively. This study indicates that T. molitor and S. litura can be used to produce S. carpocapsae. The production of S. carpocapsae with a concentration of 400 IJ / larvae on T. molitor and S. litura showed the highest total yield and body length of IJ.

Kinetics of infective juvenile production of the entomopathogenic nematode Steinernema carpocapsae in submerged monoxenic culture

2007 ◽  
Vol 31 (5) ◽  
pp. 419-426 ◽  
Author(s):  
Norberto Chavarría-Hernández ◽  
Marco-Antonio Islas-López ◽  
Gabriela Maciel-Vergara ◽  
Martha Gayosso-Canales ◽  
Adriana-Inés Rodríguez-Hernández
Keyword(s):  
Entomopathogenic Nematode ◽  
Steinernema Carpocapsae ◽  
Infective Juvenile ◽  
Monoxenic Culture ◽  
Kinetics Of

scholarly journals Role of Secondary Metabolites in Establishment of the Mutualistic Partnership between Xenorhabdus nematophila and the Entomopathogenic Nematode Steinernema carpocapsae

2014 ◽  
Vol 81 (2) ◽  
pp. 754-764 ◽  
Author(s):  
Swati Singh ◽  
David Orr ◽  
Emmanuel Divinagracia ◽  
Joseph McGraw ◽  
Kellen Dorff ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Entomopathogenic Nematode ◽  
Water Soluble ◽  
Steinernema Carpocapsae ◽  
Xenorhabdus Nematophila ◽  
Interspecies Competition ◽  
Nematode Reproduction ◽  
Content Type

ABSTRACTXenorhabdus nematophilaengages in a mutualistic partnership with the nematodeSteinernema carpocapsae, which invades insects, migrates through the gut, and penetrates into the hemocoel (body cavity). We showed previously that during invasion ofManduca sexta, the gut microbeStaphylococcus saprophyticusappeared transiently in the hemocoel, whileEnterococcus faecalisproliferated asX. nematophilabecame dominant.X. nematophilaproduces diverse secondary metabolites, including the major water-soluble antimicrobial xenocoumacin. Here, we study the role ofX. nematophilaantimicrobials in interspecies competition under biologically relevant conditions using strains lacking either xenocoumacin (ΔxcnKLstrain), xenocoumacin and the newly discovered antibiotic F (ΔxcnKL:F strain), or allngrA-derived secondary metabolites (ngrAstrain). Competition experiments were performed in Grace's insect medium, which is based on lepidopteran hemolymph.S. saprophyticuswas eliminated when inoculated into growing cultures of either the ΔxcnKLstrain or ΔxcnKL:F strain but grew in the presence of thengrAstrain, indicating thatngrA-derived antimicrobials, excluding xenocoumacin or antibiotic F, were required to eliminate the competitor. In contrast,S. saprophyticuswas eliminated when coinjected intoM. sextawith either the ΔxcnKLorngrAstrain, indicating thatngrA-derived antimicrobials were not required to eliminate the competitorin vivo.E. faecalisgrowth was facilitated when coinjected with either of the mutant strains. Furthermore, nematode reproduction inM. sextanaturally infected with infective juveniles colonized with thengrAstrain was markedly reduced relative to the level of reproduction when infective juveniles were colonized with the wild-type strain. These findings provide new insights into interspecies competition in a host environment and suggest thatngrA-derived compounds serve as signals forin vivonematode reproduction.

scholarly journals Microbial Population Dynamics in the Hemolymph of Manduca sexta Infected with Xenorhabdus nematophila and the Entomopathogenic Nematode Steinernema carpocapsae

2014 ◽  
Vol 80 (14) ◽  
pp. 4277-4285 ◽  
Author(s):  
Swati Singh ◽  
Jordan M. Reese ◽  
Ángel M. Casanova-Torres ◽  
Heidi Goodrich-Blair ◽  
Steven Forst
Keyword(s):  
Entomopathogenic Nematode ◽  
Natural Infection ◽  
Steinernema Carpocapsae ◽  
Host Immune System ◽  
Xenorhabdus Nematophila ◽  
Content Type ◽  
Host Immune Responses ◽  
Microbial Population Dynamics ◽  
Mutualistic Association

ABSTRACTXenorhabdus nematophilaengages in a mutualistic association with the nematodeSteinernema carpocapsae. The nematode invades and traverses the gut of susceptible insects.X. nematophilais released in the insect blood (hemolymph), where it suppresses host immune responses and functions as a pathogen.X. nematophilaproduces diverse antimicrobials in laboratory cultures. The natural competitors thatX. nematophilaencounters in the hemolymph and the role of antimicrobials in interspecies competition in the host are poorly understood. We show that gut microbes translocate into the hemolymph when the nematode penetrates the insect intestine. During natural infection,Staphylococcus saprophyticuswas initially present and subsequently disappeared from the hemolymph, whileEnterococcus faecalisproliferated.S. saprophyticuswas sensitive toX. nematophilaantibiotics and was eliminated from the hemolymph when coinjected withX. nematophila. In contrast,E. faecaliswas relatively resistant toX. nematophilaantibiotics. When injected by itself,E. faecalispersisted (∼103CFU/ml), but when coinjected withX. nematophila, it proliferated to ∼109CFU/ml. Injection ofE. faecalisinto the insect caused the upregulation of an insect antimicrobial peptide, while the transcript levels were suppressed whenE. faecaliswas coinjected withX. nematophila. Its relative antibiotic resistance together with suppression of the host immune system byX. nematophilamay account for the growth ofE. faecalis. At higher injected levels (106CFU/insect),E. faecaliscould kill insects, suggesting that it may contribute to virulence in anX. nematophilainfection. These findings provide new insights into the competitive events that occur early in infection afterS. carpocapsaeinvades the host hemocoel.

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