scholarly journals Partner-specific induction of Spodoptera frugiperda immune genes in response to the entomopathogenic nematobacterial complex Steinernema carpocapsae-Xenorhabdus nematophila

2019 ◽  
Author(s):  
Louise Huot ◽  
Audrey Bigourdan ◽  
Sylvie Pagès ◽  
Jean-Claude Ogier ◽  
Pierre-Alain Girard ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Spodoptera Frugiperda ◽  
Fat Body ◽  
Functional Characterization ◽  
Steinernema Carpocapsae ◽  
Symbiotic Bacteria ◽  
Xenorhabdus Nematophila ◽  
Immune Genes ◽  
Specific Induction

AbstractThe Steinernema carpocapsae-Xenorhabdus nematophila association is a nematobacterial complex (NBC) used in biological control of insect crop pests. The ability of this dual pathogen to infest and kill an insect strongly depends on the dialogue between the host’s immune system and each partner of the complex. Even though this dialogue has been extensively studied from the two partners’ points of view in several insect models, still little is known about the structure and the molecular aspects of the insects’ immune response to the dual infection. Here, we used the lepidopteran pest Spodoptera frugiperda as a model to analyze the respective impact of each NBC partner in the spatiotemporal immune responses that are induced after infestation. To this aim, we first analyzed the expression variations of the insect’s immune genes in the fat bodies and hemocytes of infested larvae by using previously obtained RNAseq data. We then selected representative immune genes for RT-qPCR investigations of the temporal variations of their expressions after infestation and of their induction levels after independent injections of each partner. We found that the fat body and the hemocytes both produce potent and stable immune responses to the infestation by the NBC, which correspond to combinations of bacterium- and nematode-induced ones. Consistent with the nature of each pathogen, we showed that X. nematophila mainly induces genes classically involved in antibacterial responses, whereas S. carpocapsae is responsible for the induction of lectins and of genes expected to be involved in melanization and cellular encapsulation. In addition, we found that two clusters of unknown genes dramatically induced by the NBC also present partner-specific induction profiles, which paves the way for their functional characterization. Finally, we discuss putative relationships between the variations of the expression of some immune genes and the NBC’s immunosuppressive strategies.Author summaryEntomopathogenic nematodes (EPNs) are living in the soil and prey upon insect larvae. They enter the insect by the natural orifices, and reach the hemocoel through the intestinal epithelium. There, they release their symbiotic bacteria that will develop within the insect and eventually kill it. Nematodes can then feed and reproduce on the insect cadaver. By using transcriptomic approaches, we previously showed that Lepidoptera larvae (caterpillars of the fall armyworm Spodoptera frugiperda) produce a strong immune response in reaction to infestation by EPNs. However, we do not know if this immune reaction is triggered by the nematode itself -Steinernema carpacapsae - or its symbiotic bacteria - Xenorhabdus nematophila. To answer this question, we present in this work a careful annotation of immunity genes in S. frugiperda and surveyed their activation by quantitative PCR in reaction to an injection of the bacteria alone, the axenic nematode or the associated complex. We found that the immune genes are selectively activated by either the bacteria or the nematode and we discuss the implication of which pathway are involved in the defense against various pathogens. We also show that a cluster of newly discovered genes, present only in Lepidoptera, is activated by the nematode only and could represent nematicide genes.

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.

scholarly journals Spodoptera frugiperdatranscriptional response to infestation bySteinernema carpocapsae

2019 ◽  
Author(s):  
Louise Huot ◽  
Simon George ◽  
Pierre-Alain Girard ◽  
Dany Severac ◽  
Nicolas Nègre ◽  
...  
Keyword(s):  
Biological Control ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Spodoptera Frugiperda ◽  
Fat Body ◽  
Steinernema Carpocapsae ◽  
Agricultural Pest ◽  
Xenorhabdus Nematophila ◽  
Transcriptional Responses ◽  
The World

AbstractSteinernema carpocapsaeis 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 bacteriumXenorhabdus nematophila, which kills the insect in less than 48 hours. Although several aspects of its interactions with insects have been extensively studied, still little is known about the immune and physiological responses of its different hosts. In order to improve this knowledge, we examined the transcriptional responses to EPN infestation of the fat body, the hemocytes and the midgut in the lepidopteran pest modelSpodoptera frugiperda(Lepidoptera: Noctuidae).Our results indicate that the tissues poorly respond to the infestation at an early time post-infestation of 8 h, even though the proliferation of the bacterial symbiont within the hemocoel is detected. Only 5 genes are differentially expressed in the fat body of the caterpillars. However, strong transcriptional responses are observed at a later time point of 15 h post-infestation in all three tissues. While few genes are differentially expressed in the midgut, 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. In addition, among the most up-regulated genes, we identified new potential immune effectors, unique to Lepidoptera, for which we present evidence of acquisition by Horizontal Gene Transfer from bacteria.Altogether, these results pave the way for further functional studies of the mobilized genes’ involvement in the interaction with the EPN.Author summaryThe Fall Armyworm,Spodoptera frugiperda, is a major agricultural pest. The caterpillars cause extensive damage to crops of importance such as corn, rice, sorghum and cotton. Originally from the Americas, it is currently becoming invasive in other parts of the world, first in Africa in 2016, then in India and now in south-east Asia. Programs of biological control against insect pests are increasingly encouraged around the world and include the use of pathogens. Entomopathogenic nematodes such asSteinernema carpocapsaeare already commercialized as organic pesticides. These nematodes live in the soil and enter the body of their insect preys. Once within the insects, they release their symbiotic bacteria (Xenorhabdus nematophilain this case), which infect and kill the host in a few hours. The nematodes can then feed on the dead insects, reproduce and resume their life cycle. It is a major challenge to understand how EPN achieve their pathogenicity as well as how the insects can resist them. Here we provide the foundation for such an interaction between EPN and a Lepidoptera. We analyzed the dynamic of transcriptional response in three insect tissues (midgut, fat body and hemocytes) upon infestation by EPN. Not many studies have been performed genome-wide on such an interaction, and none on a Lepidopteran model of economical importance. Our transcriptomic approach revealed some specificities of the Lepidopteran defense mechanisms. In particular, we discovered a set of genes, acquired in Lepidoptera from bacteria by Horizontal Gene Transfer, that probably encode proteins with antibiotic activity.

scholarly journals Immune Response of Drosophila suzukii Larvae to Infection with the Nematobacterial Complex Steinernema carpocapsae–Xenorhabdus nematophila

Insects ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 210 ◽  
Author(s):  
Anna Garriga ◽  
Maristella Mastore ◽  
Ana Morton ◽  
Fernando Garcia del Pino ◽  
Maurizio Francesco Brivio
Keyword(s):  
Immune Response ◽  
Entomopathogenic Nematodes ◽  
Humoral Response ◽  
Inhibitory Effect ◽  
Steinernema Carpocapsae ◽  
Invasive Pest ◽  
Xenorhabdus Nematophila ◽  
Drosophila Suzukii

Entomopathogenic nematodes have been proposed as biological agents for the control of Drosophila suzukii, an invasive pest of small-stone and soft-skinned fruits. Larvae of the fly are susceptible to Steinernema carpocapsae infection but the reaction of immune defenses of the host are unknown. To determine the immune response, larvae were infected with S. carpocapsae and Xenorhabdus nematophila to evaluate the effector mechanisms of both humoral and cellular processes. The symbiont bacteria presented an inhibitory effect on the phenoloxidase cascade with a low level of melanization. Besides, X. nematophila activated the synthesis of putative antimicrobial peptides on the hemolymph of infected larvae. However, those peptides presented a lower antimicrobial activity compared to hemolymph from larvae infected with non-symbiont bacteria. Xenorhabdus nematophila avoided also the phagocytosis response of hemocytes. During in vitro and in vivo assays, S. carpocapsae was not encapsulated by cells, unless the cuticle was damaged with a lipase-treatment. Hemocyte counts confirmed differentiation of lamellocytes in the early phase of infection despite the unrecognition of the nematodes. Both X. nematophila and S. carpocapsae avoided the cellular defenses of D. suzukii larvae and depressed the humoral response. These results confirmed the potential of entomopathogenic nematodes to control D. suzukii.

scholarly journals Identification of the Ricin-B-Lectin LdRBLk in the Colorado Potato Beetle and an Analysis of Its Expression in Response to Fungal Infections

2021 ◽  
Vol 7 (5) ◽  
pp. 364
Author(s):  
Ulyana Rotskaya ◽  
Vadim Kryukov ◽  
Elena Kosman ◽  
Maksim Tyurin ◽  
Viktor Glupov
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Colorado Potato Beetle ◽  
Leptinotarsa Decemlineata ◽  
Fat Body ◽  
Fungal Infections ◽  
Ricinus Communis ◽  
Metarhizium Robertsii ◽  
Expression Levels ◽  
Potato Beetle

Ricin-B-lectins (RBLs) have been identified in many groups of organisms, including coleopterans insects, particularly the Colorado potato beetle Leptinotarsa decemlineata (LdRBLs). We hypothesized that one of these LdRBLs (LdRBLk) may be involved in the immune response to fungal infections. We performed a theoretical analysis of the structure of this protein. Additionally, the expression levels of the LdRBlk gene were measured in L. decemlineata in response to infections with the fungi Metarhizium robertsii and Beauveria bassiana. The expression levels of LdRBlk in the L. decemlineata cuticle and fat body were increased in response to both infections. The induction of LdRBlk expression was dependent on the susceptibility of larvae to the fungi. Upregulation of the LdRBlk gene was also observed in response to other stresses, particularly thermal burns. Elevation of LdRBlk expression was frequently observed to be correlated with the expression of the antimicrobial peptide attacin but was not correlated with hsp90 regulation. Commercially available β-lectin of ricin from Ricinus communis was observed to inhibit the germination of conidia of the fungi. We suggest that LdRBLk is involved in antifungal immune responses in the Colorado potato beetle, either exerting fungicidal properties directly or acting as a modulator of the immune response.

scholarly journals Reliance on polyfunctional tissue leads to a reproduction-immunity tradeoff due to inherent constraint

2021 ◽  
Author(s):  
Vanika Gupta ◽  
Ashley M. Frank ◽  
Nick Matolka ◽  
Brian P. Lazzaro
Keyword(s):  
Immune Response ◽  
Drosophila Melanogaster ◽  
Immune Responses ◽  
Metabolic Control ◽  
Fat Body ◽  
Trade Off ◽  
Single Nucleus ◽  
Mechanistic Basis ◽  
New Protein ◽  
General Explanation

AbstractThe use of one tissue for multiple purposes can result in constraints, impaired function, and tradeoffs. The insect fat body performs remarkably diverse functions including metabolic control, reproductive provisioning, and systemic immune responses. Immunity and reproduction are observed to trade off in many organisms, although the mechanistic basis for the tradeoff is generally unknown. More generally, how do polyfunctional tissues simultaneously execute multiple distinct physiological functions? Using single-nucleus sequencing, we determined the Drosophila melanogaster fat body executes diverse basal functions with heterogenous cellular subpopulations. However, as an emergency function, the immune response engages the entire tissue. We found that reproductively active females exhibit impaired capacity to produce new protein in response to infection, resulting in the reproduction-immunity tradeoff. We suggest that such inherent internal limitations may provide a general explanation for the wide prevalence of physiological and evolutionary tradeoffs.

Oral Immune Activation by Disgust and Disease-Related Pictures

2015 ◽  
Vol 29 (3) ◽  
pp. 119-129 ◽  
Author(s):  
Richard J. Stevenson ◽  
Deborah Hodgson ◽  
Megan J. Oaten ◽  
Luba Sominsky ◽  
Mehmet Mahmut ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Innate Immune Response ◽  
Negative Control ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Immune Markers ◽  
Before And After ◽  
Secondary Analyses ◽  
Image Set

Abstract. Both disgust and disease-related images appear able to induce an innate immune response but it is unclear whether these effects are independent or rely upon a common shared factor (e.g., disgust or disease-related cognitions). In this study we directly compared these two inductions using specifically generated sets of images. One set was disease-related but evoked little disgust, while the other set was disgust evoking but with less disease-relatedness. These two image sets were then compared to a third set, a negative control condition. Using a wholly within-subject design, participants viewed one image set per week, and provided saliva samples, before and after each viewing occasion, which were later analyzed for innate immune markers. We found that both the disease related and disgust images, relative to the negative control images, were not able to generate an innate immune response. However, secondary analyses revealed innate immune responses in participants with greater propensity to feel disgust following exposure to disease-related and disgusting images. These findings suggest that disgust images relatively free of disease-related themes, and disease-related images relatively free of disgust may be suboptimal cues for generating an innate immune response. Not only may this explain why disgust propensity mediates these effects, it may also imply a common pathway.

Novel Toxin-antitoxin System Xn-mazEF from Xenorhabdus nematophi-la: Identification, Characterization and Functional Exploration

2020 ◽  
Vol 16 ◽  
Author(s):  
Jogendra Singh Nim ◽  
Mohit Yadav ◽  
Lalit Kumar Gautam ◽  
Chaitali Ghosh ◽  
Shakti Sahi ◽  
...  
Keyword(s):  
Interaction Analysis ◽  
Functional Characterization ◽  
Host Cells ◽  
System Control ◽  
Xenorhabdus Nematophila ◽  
Functional Features ◽  
Dynamics Simulations ◽  
Species Specific ◽  
Rna Interaction

Background: Xenorhabdus nematophila maintains species-specific mutual interaction with nematodes of Steinernema genus. Type II Toxin Antitoxin (TA) systems, the mazEF TA system controls stress and programmed cell death in bacteria. Objective: This study elucidates the functional characterization of Xn-mazEF, a mazEF homolog in X. nematophila by computational and in vitro approaches. Methods: 3 D- structural models for Xn-MazE toxin and Xn-MazF antitoxin were generated, validated and characterized for protein - RNA interaction analysis. Further biological and cellular functions of Xn-MazF toxin were also predicted. Molecular dynamics simulations of 50ns for Xn-MazF toxin complexed with nucleic acid units (DU, RU, RC, and RU) were performed. The MazF toxin and complete MazEF operon were endogenously expressed and monitored for the killing of Escherichia coli host cells under arabinose induced tightly regulated system. Results: Upon induction, E. coli expressing toxin showed rapid killing within four hours and attained up to 65% growth inhibition, while the expression of the entire operon did not show significant killing. The observation suggests that the Xn-mazEF TA system control transcriptional regulation in X. nematophila and helps to manage stress or cause toxicity leading to programmed death of cells. Conclusion: The study provides insights into structural and functional features of novel toxin, XnMazF and provides an initial inference on control of X. nematophila growth regulated by TA systems.

scholarly journals Coupled complementation of immune response genes controlling responsiveness to the H-2.2 alloantigen.

1977 ◽  
Vol 146 (2) ◽  
pp. 571-578 ◽  
Author(s):  
M E Dorf ◽  
J H Stimpfling
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Humoral Response ◽  
Mixed Lymphocyte Culture ◽  
Lymphocyte Culture ◽  
F1 Hybrids ◽  
Gene Control ◽  
Low Responder ◽  
Resistant Strains ◽  
High Level

The ability of various B10 congenic resistant strains to respond to the alloantigen H-2.2 was tested. High and low antibody-producing strains were distinguished by their anti-H-2.2 hemagglutinating respones. However, these strains do not differ in their ability to respond to these antigenic differences in the mixed lymphocyte culture. The humoral response to the H-2.2 alloantigen was shown to be controlled by two interacting genes localized within the H-2 complex. Thus, F1 hybrids prepared between parental low responder strains could yield high level immune responses. In addition, strains bearing recombinant H-2 haplotypes were used to map the two distinct genes controlling the immune response. The alleles at each locus were shown to be highly polymorphic as evidenced by the asymmetric complementation patterns observed. The restricted interactions of specific alleles was termed coupled complementation. The significance of the results in the terms of mechanisms of Ir gene control are discussed.

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