1
|
Mallick S, Kenney E, Eleftherianos I. The Activin Branch Ligand Daw Regulates the Drosophila melanogaster Immune Response and Lipid Metabolism against the Heterorhabditis bacteriophora Serine Carboxypeptidase. Int J Mol Sci 2024; 25:7970. [PMID: 39063211 PMCID: PMC11277151 DOI: 10.3390/ijms25147970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 07/16/2024] [Accepted: 07/19/2024] [Indexed: 07/28/2024] Open
Abstract
Despite impressive advances in the broad field of innate immunity, our understanding of the molecules and signaling pathways that control the host immune response to nematode infection remains incomplete. We have shown recently that Transforming Growth Factor-β (TGF-β) signaling in the fruit fly Drosophila melanogaster is activated by nematode infection and certain TGF-β superfamily members regulate the D. melanogaster anti-nematode immune response. Here, we investigate the effect of an entomopathogenic nematode infection factor on host TGF-β pathway regulation and immune function. We find that Heterorhabditis bacteriophora serine carboxypeptidase activates the Activin branch in D. melanogaster adults and the immune deficiency pathway in Activin-deficient flies, it affects hemocyte numbers and survival in flies deficient for Activin signaling, and causes increased intestinal steatosis in Activin-deficient flies. Thus, insights into the D. melanogaster signaling pathways and metabolic processes interacting with H. bacteriophora pathogenicity factors will be applicable to entomopathogenic nematode infection of important agricultural insect pests and vectors of disease.
Collapse
Affiliation(s)
| | | | - Ioannis Eleftherianos
- Infection and Innate Immunity Lab, Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA; (S.M.); (E.K.)
| |
Collapse
|
2
|
Bastin A, Eleftherianos I. Heterorhabditis bacteriophora. Trends Parasitol 2023:S1471-4922(23)00098-3. [PMID: 37188598 DOI: 10.1016/j.pt.2023.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 04/15/2023] [Accepted: 04/24/2023] [Indexed: 05/17/2023]
Affiliation(s)
- Ashley Bastin
- Infection and Innate Immunity Lab, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Ioannis Eleftherianos
- Infection and Innate Immunity Lab, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA.
| |
Collapse
|
3
|
Can Symbiotic Bacteria ( Xenorhabdus and Photorhabdus) Be More Efficient than Their Entomopathogenic Nematodes against Pieris rapae and Pentodon algerinus Larvae? BIOLOGY 2021; 10:biology10100999. [PMID: 34681098 PMCID: PMC8533234 DOI: 10.3390/biology10100999] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 09/28/2021] [Accepted: 10/02/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary Food security is the people’s main concern, and agricultural crops play a significant role in ensuring it. Agricultural pests, on the other hand, are regarded one of the most serious threats to cause a significant problem for food security. Entomopathogenic nematodes of the genera Herterorhabditids and Sterinernematids fulfil the fundamental requirements of perfect bio-control agents; however, their efficacy mostly dependent on their symbiotic bacteria. As a result, this study aimed to investigate the ability of the isolated symbiotic bacteria (Photorhabdus and Xenorhabdus) to control Pieris rapae and Pentodon algerinus larvae in comparison with their own nematodes, Heterorhabditis bacteriophora and Steinernema riobravis, respectively. The results showed that both nematode species and their symbiotic bacteria were able to suppress both insect species. However, both bacterial genera were more efficient than the investigated nematode species against P. rapae, although nematodes were superior against P. algerinus. Gas chromatography–mass spectrophotometry of Xenorhabdus sp. and Photorhabdus sp. identified the key components with the insecticidal properties. The two bacteria genera were proven to be safe and had no significant effect on normal WI-38 human cells. In conclusion, the symbiotic bacteria can be employed safely and effectively against the tested insects independently on their own entomopathogenic nematodes. Abstract Pieris rapae and Pentodon algerinus are considered a global threat to agricultural crops and food security; hence, their control is a critical issue. Heterorhabditid and Steinernematid nematodes, along with their symbiotic bacteria, can achieve the optimal biocontrol agent criterion. Therefore, this study aimed to evaluate the efficacy of Heterorhabditis bacteriophora, Steinernema riobravis, and their symbiotic bacteria (Xenorhabdus and Photorhabdus) against P. rapae and P. algerinus larvae. The virulence of entomopathogenic nematodes (EPNs) was determined at different infective juvenile concentrations and exposure times, while the symbiotic bacteria were applied at the concentration of 3 × 107 colony-forming units (CFU)/mL at different exposure times. Gas chromatography–mass spectrophotometry (GC-MS) analysis and the cytotoxic effect of Photorhabdus sp. and Xenorhabdus sp. were determined. The results indicated that H. bacteriophora, S. riobravis, and their symbiotic bacteria significantly (p ≤ 0.001) induced mortality in both insect species. However, H. bacteriophora and its symbiont, Photorhabdus sp., were more virulent. Moreover, the data clarified that both symbiotic bacteria outperformed EPNs against P. rapae but the opposite was true for P. algerinus. GC-MS analysis revealed the main active compounds that have insecticidal activity. However, the results revealed that there was no significant cytotoxic effect. In conclusion, H. bacteriophora, S. riobravis, and their symbiotic bacteria can be an optimal option for bio-controlling both insect species. Furthermore, both symbiotic bacteria can be utilized independently on EPNs for the management of both pests, and, hence, they can be safely incorporated into biocontrol programs and tested against other insect pests.
Collapse
|
4
|
Douglas B, Oyesola O, Cooper MM, Posey A, Tait Wojno E, Giacomin PR, Herbert DR. Immune System Investigation Using Parasitic Helminths. Annu Rev Immunol 2021; 39:639-665. [PMID: 33646858 DOI: 10.1146/annurev-immunol-093019-122827] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Coevolutionary adaptation between humans and helminths has developed a finely tuned balance between host immunity and chronic parasitism due to immunoregulation. Given that these reciprocal forces drive selection, experimental models of helminth infection are ideally suited for discovering how host protective immune responses adapt to the unique tissue niches inhabited by these large metazoan parasites. This review highlights the key discoveries in the immunology of helminth infection made over the last decade, from innate lymphoid cells to the emerging importance of neuroimmune connections. A particular emphasis is placed on the emerging areas within helminth immunology where the most growth is possible, including the advent of genetic manipulation of parasites to study immunology and the use of engineered T cells for therapeutic options. Lastly,we cover the status of human challenge trials with helminths as treatment for autoimmune disease, which taken together, stand to keep the study of parasitic worms at the forefront of immunology for years to come.
Collapse
Affiliation(s)
- Bonnie Douglas
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; ,
| | - Oyebola Oyesola
- Department of Immunology, University of Washington, Seattle, Washington 98109, USA; ,
| | - Martha M Cooper
- Centre for Molecular Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland 4878, Australia; ,
| | - Avery Posey
- Parker Institute for Cancer Immunotherapy, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; .,Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.,Corporal Michael J. Crescenz VA Medical Center, Philadelphia, Pennsylvania 19104, USA
| | - Elia Tait Wojno
- Department of Immunology, University of Washington, Seattle, Washington 98109, USA; ,
| | - Paul R Giacomin
- Centre for Molecular Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland 4878, Australia; ,
| | - De'Broski R Herbert
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; ,
| |
Collapse
|
5
|
Colgan TJ, Carolan JC, Sumner S, Blaxter ML, Brown MJF. Infection by the castrating parasitic nematode Sphaerularia bombi changes gene expression in Bombus terrestris bumblebee queens. INSECT MOLECULAR BIOLOGY 2020; 29:170-182. [PMID: 31566835 DOI: 10.1111/imb.12618] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 08/20/2019] [Accepted: 09/13/2019] [Indexed: 06/10/2023]
Abstract
Parasitism can result in dramatic changes in host phenotype, which are themselves underpinned by genes and their expression. Understanding how hosts respond at the molecular level to parasites can therefore reveal the molecular architecture of an altered host phenotype. The entomoparasitic nematode Sphaerularia bombi is a parasite of bumblebee (Bombus) hosts where it induces complex behavioural changes and host castration. To examine this interaction at the molecular level, we performed genome-wide transcriptional profiling using RNA-Sequencing (RNA-Seq) of S. bombi-infected Bombus terrestris queens at two critical time-points: during and just after overwintering diapause. We found that infection by S. bombi affects the transcription of genes underlying host biological processes associated with energy usage, translation, and circadian rhythm. We also found that the parasite affects the expression of immune genes, including members of the Toll signalling pathway providing evidence for a novel interaction between the parasite and the host immune response. Taken together, our results identify host biological processes and genes affected by an entomoparasitic nematode providing the first steps towards a molecular understanding of this ecologically important host-parasite interaction.
Collapse
Affiliation(s)
- T J Colgan
- Department of Zoology, School of Natural Sciences, University of Dublin, Trinity College, Dublin, Ireland
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland
| | - J C Carolan
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - S Sumner
- Centre for Biodiversity and Environment Research, University College London, London, UK
| | - M L Blaxter
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | - M J F Brown
- Centre of Ecology, Evolution and Behaviour, Department of Biological Sciences, Royal Holloway University of London, Egham, UK
| |
Collapse
|
6
|
Dlamini BE, Dlamini N, Masarirambi MT, A. NK. Control of the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) larvae in laboratory using entomopathogenic nematodes from subtropical environment. J Nematol 2020; 52:1-8. [PMID: 32141267 PMCID: PMC7265902 DOI: 10.21307/jofnem-2020-013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Indexed: 11/11/2022] Open
Abstract
Tomato (Solanum esculentum) is one of the vegetable crops grown by both smallholder and commercial farmers in the Kingdom of Eswatini. Tomato leaf miner, Tuta absoluta M. is a major insect pest of tomatoes resulting in reduced tomato yields throughout the country. The study investigated the virulence of two sub-tropical EPN species on T. absoluta larvae. Steinernema yirgalemense and S. jeffreyense at different concentrations (0, 20, 40, 60 IJs/insect) were screened for efficacy (i.e. mortality rate) against larvae of T. absoluta in laboratory bioassays. Results obtained showed that S. yirgalemense and S. jeffreyense were able to kill T. absoluta larvae without significant differences between the two EPN species in 24-well bioassay trays. Significantly higher (p < 0.05) mortality was observed when 60 IJs/insect was used. The combination of S. yirgalemense at 60 IJs/insect (100%) and S. jeffreyense at 60 IJs/insect (98.3%) resulted in significantly higher (p < 0.05) mortality, compared with the other four combinations of EPN and concentration tested. In the leaf bioassays, S. yirgalemense (58.8%) resulted in significantly higher (p < 0.05) mean mortality compared to S. jeffreyense (46.4%). Steinernema yirgalemense at 60 IJs/insect resulted in significantly higher mean mortality compared to the other EPN and concentration combinations in the leaf bioassay. The results indicated that both EPNs tested were effective against T. absoluta larvae. Steinernema yirgalemense at 60 IJs/insect can effectively find T. absoluta larvae inside leaf mines, but large-scale field trials are recommended to demonstrate the potential use of the biocontrol agent within integrated pest management programs. Tomato (Solanum esculentum) is one of the vegetable crops grown by both smallholder and commercial farmers in the Kingdom of Eswatini. Tomato leaf miner, Tuta absoluta M. is a major insect pest of tomatoes resulting in reduced tomato yields throughout the country. The study investigated the virulence of two sub-tropical EPN species on T. absoluta larvae. Steinernema yirgalemense and S. jeffreyense at different concentrations (0, 20, 40, 60 IJs/insect) were screened for efficacy (i.e. mortality rate) against larvae of T. absoluta in laboratory bioassays. Results obtained showed that S. yirgalemense and S. jeffreyense were able to kill T. absoluta larvae without significant differences between the two EPN species in 24-well bioassay trays. Significantly higher (p < 0.05) mortality was observed when 60 IJs/insect was used. The combination of S. yirgalemense at 60 IJs/insect (100%) and S. jeffreyense at 60 IJs/insect (98.3%) resulted in significantly higher (p < 0.05) mortality, compared with the other four combinations of EPN and concentration tested. In the leaf bioassays, S. yirgalemense (58.8%) resulted in significantly higher (p < 0.05) mean mortality compared to S. jeffreyense (46.4%). Steinernema yirgalemense at 60 IJs/insect resulted in significantly higher mean mortality compared to the other EPN and concentration combinations in the leaf bioassay. The results indicated that both EPNs tested were effective against T. absoluta larvae. Steinernema yirgalemense at 60 IJs/insect can effectively find T. absoluta larvae inside leaf mines, but large-scale field trials are recommended to demonstrate the potential use of the biocontrol agent within integrated pest management programs.
Collapse
Affiliation(s)
- Bonginkhosi E. Dlamini
- Department of Crop Production, Faculty of Agriculture, University of Eswatini, P.O. Luyengo, M205, Manzini, Kingdom of Eswatini
| | - Nelisiwe Dlamini
- Department of Crop Production, Faculty of Agriculture, University of Eswatini, P.O. Luyengo, M205, Manzini, Kingdom of Eswatini
| | - Michael T. Masarirambi
- Department of Horticulture, Faculty of Agriculture, University of Eswatini, P.O. Luyengo, M205, Manzini, Kingdom of Eswatini
| | - Nxumalo Kwanele A.
- Department of Horticulture, Faculty of Agriculture, University of Eswatini, P.O. Luyengo, M205, Manzini, Kingdom of Eswatini
| |
Collapse
|
7
|
Mbata GN, Shapiro-Ilan DI, Alborn HT, Strand MR. Preferential infectivity of entomopathogenic nematodes in an envenomed host. Int J Parasitol 2019; 49:737-745. [PMID: 31306662 DOI: 10.1016/j.ijpara.2019.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 05/16/2019] [Accepted: 05/22/2019] [Indexed: 01/11/2023]
Abstract
Entomopathogenic nematodes and parasitoid wasps are used as biological control agents for management of insect pests such as the Indian meal moth, Plodia interpunctella. The parasitoid wasp Habrobracon hebetor injects a paralytic venom into P. interpunctella larvae before laying eggs. A previous study reported that the entomopathogenic nematode Heterorhabditis indica preferentially infects P. interpunctella that have been envenomed by H. hebetor while results in this study showed a similar preference by the entomopathogenic nematode, Steinernema glaseri. We therefore tested four hypotheses for why nematode infection rates are higher in envenomed hosts: (1) elevated CO2 emission from envenomed hosts attracts nematodes, (2) paralysis prevents hosts from escaping nematodes, (3) volatile chemicals emitted from envenomed hosts attract nematodes and increase infection, and (4) reduced immune defenses in envenomed hosts increase nematode survival. Results showed that envenomed P. interpunctella larvae emitted lower amounts of CO2 than non-envenomed larvae. Physical immobilization of P. interpunctella larvae did not increase infection rates by S. glaseri but did increase infection rates by H. indica. Emissions from envenomed hosts were collected and analyzed by thermal desorption gas chromatography/mass spectrometry. The most abundant compound, 3-methyl-3-buten-1-ol, was found to be an effective cue for S. glaseri attraction and infection but was not an effective stimulus for H. indica. Envenomed P. interpunctella exhibited a stronger immune response toward nematodes than non-envenomed hosts. Altogether, we conclude that different mechanisms underlie preferential infection in the two nematode species: host immobilization for H. indica and chemical cues for S. glaseri.
Collapse
Affiliation(s)
- George N Mbata
- Agricultural Research Station, Fort Valley State University, 1005 University Drive, Fort Valley, GA 31030, USA
| | - David I Shapiro-Ilan
- USDA, Agricultural Research Service, Southeastern Fruit and Tree Nut Research Laboratory, 21 Dunbar Road, Byron, GA 31008, USA.
| | - Hans T Alborn
- USDA-ARS Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32608, USA
| | - Michael R Strand
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
| |
Collapse
|
8
|
The prophenoloxidase system in Drosophila participates in the anti-nematode immune response. Mol Immunol 2019; 109:88-98. [DOI: 10.1016/j.molimm.2019.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 03/19/2019] [Accepted: 03/19/2019] [Indexed: 12/24/2022]
|
9
|
Wang GJ, Zhuo XR, Wang WW, Liu XS, Wang GX, Wang JL. Molecular characterization of immune responses of Helicoverpa armigera to infection with the mermithid nematode Ovomermis sinensis. BMC Genomics 2019; 20:161. [PMID: 30813894 PMCID: PMC6391810 DOI: 10.1186/s12864-019-5544-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 02/18/2019] [Indexed: 01/02/2023] Open
Abstract
Background Mermithid nematodes, such as Ovomermis sinensis, display a broad host range including some lepidopteran pests. Infective juveniles penetrate their host through the cuticle, complete their growth within the hemocoel and eventually kill the host upon their emergence. Hence, mermithid nematodes are considered potential biological control agents of insect pests. Our previous data indicate that the infection rate of O. sinensis on cotton bollworm (Helicoverpa armigera) is low, which may be largely due to the strong immune system of the host. However, current knowledge on the interactions of mermithid nematodes with their hosts and the mechanisms employed by hosts to defend themselves against mermithid nematodes is limited. Results Here, we investigated the response of H. armigera to O. sinensis infection. Parasitism by O. sinensis caused a sharp decline in the survival rate of H. armigera. The hemocytic phagocytosis ability, antibacterial activity, and phenoloxidase (PO) activity in plasma of H. armigera increased at 1 d post parasitism (dpp) but decreased at 3 dpp. Further, we investigated gene expression in the fat body of parasitized and non-parasitized H. armigera larvae at 1, 3, and 5 dpp using a digital gene expression system. In total, 41, 60 and 68 immune-related differentially expressed genes were identified at 1, 3, and 5 dpp, respectively. These genes encoded pattern recognition receptors (PRRs), antimicrobial peptides (AMPs), serine proteases (SPs), SP inhibitors, mucins and other immune-related proteins. The expression of most PRRs, AMPs, SPs, and mucins was upregulated in the fat body of larvae at 1 dpp, downregulated at 3 dpp, and then again upregulated at 5 dpp by O. sinensis. The increased expression of SP inhibitors may contribute to the inhibited PO activity at 5 dpp. Conclusions This study demonstrates that parasitism by O. sinensis modulates the immune reaction of the host H. armigera by altering the expression of immune-related genes. Our data provide a basis for future investigation of the molecular mechanisms employed by the mermithid nematode O. sinensis to modulate the immunity of the host H. armigera. These data will also likely facilitate the improvement of success in parasitism of H. armigera by O. sinensis. Electronic supplementary material The online version of this article (10.1186/s12864-019-5544-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Gui-Jie Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Xiao-Rong Zhuo
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Wen-Wen Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Xu-Sheng Liu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Guo-Xiu Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Jia-Lin Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China.
| |
Collapse
|
10
|
Cellular immunity in the insect Galleria mellonella against insect non-parasitic nematodes. Parasitology 2018; 146:708-715. [DOI: 10.1017/s003118201800210x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
AbstractImmunity to microbial infections is well understood; however, information regarding the immunity to parasitic multicellular organisms remains lacking. To understand innate host cellular immunity to nematodes, we compared the cellular response of the greater wax moth (Galleria mellonella) larvae against the non-parasitic, bacterial-feeding nematode Caenorhabditis elegans and pathogenic nematode Heterorhabditis bacteriophora. When intact first-instar or dauer larvae of C. elegans were injected into a G. mellonella larva, most of the nematodes were alive and not confined by the surrounding reaction by insect haemocytes (encapsulation), similarly as the pathogenic nematode, whereas most of the heat-killed nematodes of both species were severely encapsulated by 24 h after inoculation. Other non-parasitic nematodes were also not encapsulated. Surprisingly, C. elegans injected into the insect haemocoel grew and propagated in the live insect, resulting in death of the host insect. Our results suggest that C. elegans has some basic mechanisms to evade immunity of G. mellonenlla and grow in the haemocoel.
Collapse
|
11
|
Mastore M, Quadroni S, Toscano A, Mottadelli N, Brivio MF. Susceptibility to entomopathogens and modulation of basal immunity in two insect models at different temperatures. J Therm Biol 2018; 79:15-23. [PMID: 30612676 DOI: 10.1016/j.jtherbio.2018.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 10/31/2018] [Accepted: 11/12/2018] [Indexed: 11/30/2022]
Abstract
In this work, we analysed the efficacy of different commercial bio-insecticides (Steinernema feltiae, Steinernema carpocapsae, Heterorhabditis bacteriophora and Bacillus thuringiensis) by valuating the mortality induced on two insect models, Galleria mellonella (Lepidoptera) and Sarcophaga africa (Diptera) after exposure to different temperatures (10, 20 and 30 °C). Moreover, we investigated the effects of temperature on the basal humoral immunity of the two target insects; particularly, phenoloxidase (PO) and lysozyme activity. Our results show that G. mellonella is susceptible to all bio-insecticides at all the examined temperatures, except when infected at 10 °C with S. carpocapsae and at 30 °C with S. feltiae and B. thuringiensis. S. africa is more susceptible at 30 °C to all bioinsecticides; whereas, when infected at 10 and 20 °C, H. bacteriophora is the most efficient. Temperature modulates PO activity of both G. mellonella and S. africa, otherwise variations in lysozyme activity is observed only in G. mellonella. Except for a possible correlation between the increased lysozyme activity and the delayed Bt efficacy recorded on G. mellonella at 30 °C, a different resistance to bio-insecticides at different temperatures does not seem to be associated to variations of the host basal immunity, probably due to immunoevasive and immunodepressive strategies of these entomopathogens.
Collapse
Affiliation(s)
- Maristella Mastore
- Lab. of Comparative Immunology and Parasitology, Dept. of Theoretical and Applied Sciences, University of Insubria, Varese, Italy
| | - Silvia Quadroni
- Lab. of Ecology, Dept. of Science and High Technology, University of Insubria, Varese, Italy
| | - Andrea Toscano
- Lab. of Comparative Immunology and Parasitology, Dept. of Theoretical and Applied Sciences, University of Insubria, Varese, Italy
| | - Nicolò Mottadelli
- Lab. of Comparative Immunology and Parasitology, Dept. of Theoretical and Applied Sciences, University of Insubria, Varese, Italy
| | - Maurizio F Brivio
- Lab. of Comparative Immunology and Parasitology, Dept. of Theoretical and Applied Sciences, University of Insubria, Varese, Italy.
| |
Collapse
|
12
|
Yadav S, Eleftherianos I. The Imaginal Disc Growth Factors 2 and 3 participate in the Drosophila response to nematode infection. Parasite Immunol 2018; 40:e12581. [PMID: 30107045 DOI: 10.1111/pim.12581] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 07/11/2018] [Accepted: 08/09/2018] [Indexed: 01/13/2023]
Abstract
The Drosophila imaginal disc growth factors (IDGFs) induce the proliferation of imaginal disc cells and terminate cell proliferation at the end of larval development. However, the participation of Idgf-encoding genes in other physiological processes of Drosophila including the immune response to infection is not fully understood. Here, we show the contribution of Idgf2 and Idgf3 in the Drosophila response to infection with Steinernema carpocapsae nematodes carrying or lacking their mutualistic Xenorhabdus nematophila bacteria (symbiotic or axenic nematodes, respectively). We find that Idgf2 and Idgf3 are upregulated in Drosophila larvae infected with symbiotic or axenic Steinernema and inactivation of Idgf2 confers a survival advantage to Drosophila larvae against axenic nematodes. Inactivation of Idgf2 induces the Imd and Jak/Stat pathways, whereas inactivation of Idgf3 induces the Imd, Toll and Jak/Stat pathways. We also show that inactivation of the Imd pathway receptor PGRP-LE upregulates Idgf2 against Steinernema nematode infection. Finally, we demonstrate that inactivation of Idgf3 induces the recruitment of larval haemocytes in response to Steinernema. Our results indicate that Idgf2 and Idgf3 might be involved in different yet crucial immune functions in the Drosophila antinematode immune response. Similar findings will promote the development of new targets for species-specific pest control strategies.
Collapse
Affiliation(s)
- Shruti Yadav
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia
| | - Ioannis Eleftherianos
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia
| |
Collapse
|
13
|
Yadav S, Eleftherianos I. Prolonged Storage Increases Virulence of Steinernema Entomopathogenic Nematodes Toward Drosophila Larvae. J Parasitol 2018; 104:722-725. [PMID: 30088785 DOI: 10.1645/18-91] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Entomopathogenic nematodes are excellent organisms for dissecting the molecular basis of parasitism and probing the insect innate immune system. The nematode parasite Steinernema carpocapsae is a potent pathogen of insects that has emerged recently as a model for parasitic infection and anti-nematode immune signaling and response. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila, which are also pathogenic to insects. Separation of nematodes from their associated bacteria facilitates mechanistic studies focusing on the impact of the parasites without considering the contribution of their bacterial partners. An important aspect in insect infection experiments with entomopathogenic nematodes includes the storage duration of the parasites. Here we have infected larvae of the model insect Drosophila melanogaster with S. carpocapsae nematodes that had been stored for 3 wk or 3 mo. Survival data consistently revealed that infective juveniles with prolonged storage exhibit substantially increased virulence toward D. melanogaster larvae compared with those that had been stored for a shorter time, and the presence of mutualistic X. nematophila in the nematodes does not influence this result. Although the basis for this effect is currently unknown, these surprising findings indicate that prolonged nematode storage can markedly alter virulence. This is significant knowledge that should be taken into account in functional assays involving infection with parasitic nematodes. Future efforts will focus on the identification and characterization of the factors that might determine the interrelationship between prolonged storage and virulence in nematode parasites.
Collapse
Affiliation(s)
- Shruti Yadav
- Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 22nd Street NW, Washington, District of Columbia 20052
| | - Ioannis Eleftherianos
- Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 22nd Street NW, Washington, District of Columbia 20052
| |
Collapse
|
14
|
Hoinville ME, Wollenberg AC. Changes in Caenorhabditis elegans gene expression following exposure to Photorhabdus luminescens strain TT01. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 82:165-176. [PMID: 29203330 DOI: 10.1016/j.dci.2017.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/05/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
Photorhabdus bacteria enter into a mutualistic symbiosis with Heterorhabditis nematodes to infect insect larvae. However, they rapidly kill the model nematode Caenorhabditis elegans. One hypothesis for these divergent outcomes is that the nematode defense responses differ. To begin testing this hypothesis, we have systematically analyzed available data on the transcriptional response of C. elegans to P. luminescens strain Hb. From a starting pool of over 7000 differentially expressed genes, we carefully chose 21 Heterorhabditis-conserved genes to develop as comparative markers. Using newly designed and validated qRT-PCR primers, we measured expression of these genes in C. elegans exposed to the sequenced TT01 strain of P. luminescens, on two different media types. Almost all (18/21) of the genes showed a significant response to P. luminescens strain TT01. One response is dependent on media type, and a subset of genes may respond differentially to distinct strains. Overall, we have established useful resources and generated new hypotheses regarding how C. elegans responds to P. luminescens infection.
Collapse
Affiliation(s)
- Megan E Hoinville
- Biology Department, Kalamazoo College, 1200 Academy St., Kalamazoo, MI 49006, USA
| | - Amanda C Wollenberg
- Biology Department, Kalamazoo College, 1200 Academy St., Kalamazoo, MI 49006, USA.
| |
Collapse
|
15
|
Eleftherianos I, Yadav S, Kenney E, Cooper D, Ozakman Y, Patrnogic J. Role of Endosymbionts in Insect-Parasitic Nematode Interactions. Trends Parasitol 2017; 34:430-444. [PMID: 29150386 DOI: 10.1016/j.pt.2017.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/12/2017] [Accepted: 10/19/2017] [Indexed: 12/12/2022]
Abstract
Endosymbiotic bacteria exist in many animals where they develop relationships that affect certain physiological processes in the host. Insects and their nematode parasites form great models for understanding the genetic and molecular basis of immune and parasitic processes. Both organisms contain endosymbionts that possess the ability to interfere with certain mechanisms of immune function and pathogenicity. This review summarizes recent information on the involvement of insect endosymbionts in the response to parasitic nematode infections, and the influence of nematode endosymbionts on specific aspects of the insect immune system. Analyzing this information will be particularly useful for devising endosymbiont-based strategies to intervene in insect immunity or nematode parasitism for the efficient management of noxious insects in the field.
Collapse
Affiliation(s)
- Ioannis Eleftherianos
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA.
| | - Shruti Yadav
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Eric Kenney
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Dustin Cooper
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Yaprak Ozakman
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| | - Jelena Patrnogic
- Insect Infection and Immunity Laboratory, Department of Biological Sciences, The George Washington University, Science and Engineering Hall, 800 22nd Street NW, Washington, DC 20052, USA
| |
Collapse
|
16
|
Darsouei R, Karimi J, Ghadamyari M, Hosseini M. Differential Change Patterns of Main Antimicrobial Peptide Genes During Infection of Entomopathogenic Nematodes and Their Symbiotic Bacteria. J Parasitol 2017; 103:349-358. [PMID: 28395586 DOI: 10.1645/16-162] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The expression of antimicrobial peptides (AMPs) as the main humoral defense reactions of insects during infection by entomopathogenic nematodes (EPNs) and their symbiont is addressed herein. Three AMPs, attacin, cecropin, and spodoptericin, were evaluated in the fifth instar larvae of Spodoptera exigua Hübner (beet armyworm) when challenged with Steinernema carpocapsae or Heterorhabditis bacteriophora. The results indicated that attacin was expressed to a greater extent than either cecropin or spodoptericin. While spodoptericin was expressed to a much lesser extent, this AMP was induced against Gram-positive bacteria, and thus not expressed after penetration of Xenorhabdus nematophila and Photorhabdus luminescens. Attacin and cecropin in the larvae treated with S. carpocapsae at 8 hr post-injection (PI) attained the maximum expression levels and were 138.42-fold and 65.84-fold greater than those of larvae infected with H. bacteriophora, respectively. Generally, the ability of H. bacteriophora to suppress attacin, cecropin, and spodoptericin was greater than that of S. carpocapsae. According to the results, the expression of AMPs by Sp. exigua larvae against S. carpocapsae was determined in the 4 statuses of monoxenic nematode, axenic nematode, live symbiotic bacterium, and dead symbiotic bacterium. The expression of attacin in larvae treated with a monoxenic nematode and live bacterium at 8 and 2 hr PI, respectively, were increased to the maximum amount. Live X. nematophila was the strongest agent for the suppression of attacin. The expression of cecropin against monoxenic nematodes and live symbiotic bacteria at 8 and 4 hr PI, respectively, reached the maximum amount while the expression levels of attacin and cecropin for axenic nematodes were lesser and stable. The results highlighted that the ability of P. luminescens in AMPs suppression was much more than X. nematophila. The results also showed that the effect of symbiotic bacterium in suppressing attacin and cecropin expression was greater than that of a monoxenic nematode; this result provided deep insight into the expression pattern parallels and fluctuations of the main AMPs during nematode infection.
Collapse
Affiliation(s)
- Reyhaneh Darsouei
- Biocontrol and Insect Pathology Laboratory, Department of Plant Protection, School of Agriculture, Ferdowsi University of Mashhad, 91779-48974 Mashhad, Iran
| | - Javad Karimi
- Biocontrol and Insect Pathology Laboratory, Department of Plant Protection, School of Agriculture, Ferdowsi University of Mashhad, 91779-48974 Mashhad, Iran
| | - Mohammad Ghadamyari
- Biocontrol and Insect Pathology Laboratory, Department of Plant Protection, School of Agriculture, Ferdowsi University of Mashhad, 91779-48974 Mashhad, Iran
| | - Mojtaba Hosseini
- Biocontrol and Insect Pathology Laboratory, Department of Plant Protection, School of Agriculture, Ferdowsi University of Mashhad, 91779-48974 Mashhad, Iran
| |
Collapse
|
17
|
Identification of candidate infection genes from the model entomopathogenic nematode Heterorhabditis bacteriophora. BMC Genomics 2017; 18:8. [PMID: 28049427 PMCID: PMC5209865 DOI: 10.1186/s12864-016-3468-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 12/23/2016] [Indexed: 12/22/2022] Open
Abstract
Background Despite important progress in the field of innate immunity, our understanding of host immune responses to parasitic nematode infections lags behind that of responses to microbes. A limiting factor has been the obligate requirement for a vertebrate host which has hindered investigation of the parasitic nematode infective process. The nematode parasite Heterorhabditis bacteriophora offers great potential as a model to genetically dissect the process of infection. With its mutualistic Photorhabdus luminescens bacteria, H. bacteriophora invades multiple species of insects, which it kills and exploits as a food source for the development of several nematode generations. The ability to culture the life cycle of H. bacteriophora on plates growing the bacterial symbiont makes it a very exciting model of parasitic infection that can be used to unlock the molecular events occurring during infection of a host that are inaccessible using vertebrate hosts. Results To profile the transcriptional response of an infective nematode during the early stage of infection, we performed next generation RNA sequencing on H. bacteriophora IJs incubated in Manduca sexta hemolymph plasma for 9 h. A subset of up-regulated and down-regulated genes were validated using qRT-PCR. Comparative analysis of the transcriptome with untreated controls found a number of differentially expressed genes (DEGs) which cover a number of different functional categories. A subset of DEGs is conserved across Clade V parasitic nematodes revealing an array of candidate parasitic genes. Conclusions Our analysis reveals transcriptional changes in the regulation of a large number of genes, most of which have not been shown previously to play a role in the process of infection. A significant proportion of these genes are unique to parasitic nematodes, suggesting the identification of a group of parasitism factors within nematodes. Future studies using these candidates may provide functional insight into the process of nematode parasitism and also the molecular evolution of parasitism within nematodes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3468-6) contains supplementary material, which is available to authorized users.
Collapse
|
18
|
Kushwah J, Kumar P, Garg V, Somvanshi VS. Discovery of a Highly Virulent Strain of Photorhabdus luminescens ssp . akhurstii from Meghalaya, India. Indian J Microbiol 2016; 57:125-128. [PMID: 28148990 DOI: 10.1007/s12088-016-0628-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/13/2016] [Indexed: 11/29/2022] Open
Abstract
Photorhabdus is an insect-pathogenic Gram negative enterobacterium found in the gut of Heterorhabditis nematodes. Photorhabdus is highly virulent to insects, and can kill insects rapidly upon injection at very low concentrations of one to few cells. We characterized the virulence of Photorhabdus symbionts isolated from the Heterorhabditis nematodes collected from various parts of India by injecting different concentrations of bacterial cells into fourth instar larval stage of insect Galleria mellonella. Photorhabdus luminescens ssp. akhurstii strain IARI-SGMG3 from Meghalaya was identified as the most virulent of all the tested strains on the basis of LT50 and LC50 values. This study forms a basis for further investigations on the genetic basis of virulence in Photorhabdus bacteria.
Collapse
Affiliation(s)
- Jyoti Kushwah
- Division of Nematology, ICAR- Indian Agricultural Research Institute, New Delhi, 110012 India.,Department of Biotechnology and Biosciences, Banasthali Vidyapeeth, Jaipur, Rajasthan India
| | - Puneet Kumar
- Division of Nematology, ICAR- Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Veena Garg
- Department of Biotechnology and Biosciences, Banasthali Vidyapeeth, Jaipur, Rajasthan India
| | - Vishal Singh Somvanshi
- Division of Nematology, ICAR- Indian Agricultural Research Institute, New Delhi, 110012 India
| |
Collapse
|
19
|
Eleftherianos I, Castillo JC, Patrnogic J. TGF-β signaling regulates resistance to parasitic nematode infection in Drosophila melanogaster. Immunobiology 2016; 221:1362-1368. [PMID: 27473342 DOI: 10.1016/j.imbio.2016.07.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 07/19/2016] [Accepted: 07/22/2016] [Indexed: 12/13/2022]
Abstract
Over the past decade important advances have been made in the field of innate immunity; however, our appreciation of the signaling pathways and molecules that participate in host immune responses to parasitic nematode infections lags behind that of responses to microbial challenges. Here we have examined the regulation and immune activity of Transforming Growth Factor-beta (TGF-β) signaling in the model host Drosophila melanogaster upon infection with the nematode parasites Heterorhabditis gerrardi and H. bacteriophora containing their mutualistic bacteria Photorhabdus. We have found that the genes encoding the Activin and Bone Morphogenic Protein (BMP) ligands Dawdle (Daw) and Decapentaplegic (Dpp) are transcriptionally induced in flies responding to infection with the nematode parasites, containing or lacking their associated bacteria. We also show that deficient Daw or Dpp regulates the survival of D. melanogaster adults to the pathogens, whereas inactivation of Daw reduces the persistence of the nematodes in the mutant flies. These findings demonstrate a novel role for the TGF-β signaling pathways in the host anti-nematode immune response. Understanding the molecular mechanisms of host anti-nematode processes will potentially lead to the development of novel means for the efficient control of parasitic nematodes.
Collapse
Affiliation(s)
- Ioannis Eleftherianos
- Department of Biological Sciences, The George Washington University, Washington, DC, USA.
| | - Julio Cesar Castillo
- Department of Biological Sciences, The George Washington University, Washington, DC, USA; Laboratory of Malaria and Vector Research, National Institutes of Health, MD, USA
| | - Jelena Patrnogic
- Department of Biological Sciences, The George Washington University, Washington, DC, USA
| |
Collapse
|
20
|
Shapiro‐Ilan D, Raymond B. Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes. Evol Appl 2016; 9:462-70. [PMID: 26989437 PMCID: PMC4778107 DOI: 10.1111/eva.12348] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/28/2015] [Accepted: 11/16/2015] [Indexed: 12/31/2022] Open
Abstract
Cooperative secretion of virulence factors by pathogens can lead to social conflict when cheating mutants exploit collective secretion, but do not contribute to it. If cheats outcompete cooperators within hosts, this can cause loss of virulence. Insect parasitic nematodes are important biocontrol tools that secrete a range of significant virulence factors. Critically, effective nematodes are hard to maintain without live passage, which can lead to virulence attenuation. Using experimental evolution, we tested whether social cheating might explain unstable virulence in the nematode Heterorhabditis floridensis by manipulating relatedness via multiplicity of infection (MOI), and the scale of competition. Passage at high MOI, which should reduce relatedness, led to loss of fitness: virulence and reproductive rate declined together and all eight independent lines suffered premature extinction. As theory predicts, relatedness treatments had more impact under stronger global competition. In contrast, low MOI passage led to more stable virulence and increased reproduction. Moreover, low MOI lineages showed a trade-off between virulence and reproduction, particularly for lines under stronger between-host competition. Overall, this study indicates that evolution of virulence theory is valuable for the culture of biocontrol agents: effective nematodes can be improved and maintained if passage methods mitigate possible social conflicts.
Collapse
Affiliation(s)
| | - Ben Raymond
- Royal Holloway University of LondonEghamSurreyUK
- Imperial College LondonSilwood Park CampusAscotBerksUK
| |
Collapse
|
21
|
Abstract
Be it their pervasiveness, experimental tractability or their impact on human health and agriculture, nematode–bacterium associations are far-reaching research subjects. Although the omics hype did not spare them and helped reveal mechanisms of communication and exchange between the associated partners, a huge amount of knowledge still awaits to be harvested from their study. Here, I summarize and compare the kind of research that has been already performed on the model nematode Caenorhabditis elegans and on symbiotic nematodes, both marine and entomopathogenic ones. The emerging picture highlights how complementing genetic studies with ecological ones (in the case of well-established genetic model systems such as C. elegans) and vice versa (in the case of the yet uncultured Stilbonematinae) will deepen our understanding of how microbial symbioses evolved and how they impact our environment. Nematode–bacterium associations are major research subjects. Complementing genetic studies with ecological ones is necessary to boost our understanding of how microbial symbioses evolved and how they impact the environment.
Collapse
Affiliation(s)
- Silvia Bulgheresi
- Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| |
Collapse
|
22
|
Insect Immunity to Entomopathogenic Nematodes and Their Mutualistic Bacteria. Curr Top Microbiol Immunol 2016; 402:123-156. [PMID: 27995342 DOI: 10.1007/82_2016_52] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Entomopathogenic nematodes are important organisms for the biological control of insect pests and excellent models for dissecting the molecular basis of the insect immune response against both the nematode parasites and their mutualistic bacteria. Previous research involving the use of various insects has found distinct differences in the number and nature of immune mechanisms that are activated in response to entomopathogenic nematode parasites containing or lacking their associated bacteria. Recent studies using model insects have started to reveal the identity of certain molecules with potential anti-nematode or antibacterial activity as well as the molecular components that nematodes and their bacteria employ to evade or defeat the insect immune system. Identification and characterization of the genes that regulate the insect immune response to nematode-bacteria complexes will contribute significantly to the development of improved practices to control insects of agricultural and medical importance, and potentially nematode parasites that infect mammals, perhaps even humans.
Collapse
|
23
|
Eicosanoids mediate Galleria mellonella immune response to hemocoel injection of entomopathogenic nematode cuticles. Parasitol Res 2015; 115:597-608. [DOI: 10.1007/s00436-015-4776-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 10/06/2015] [Indexed: 11/25/2022]
|
24
|
Yadav S, Shokal U, Forst S, Eleftherianos I. An improved method for generating axenic entomopathogenic nematodes. BMC Res Notes 2015; 8:461. [PMID: 26386557 PMCID: PMC4575472 DOI: 10.1186/s13104-015-1443-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 09/11/2015] [Indexed: 12/19/2022] Open
Abstract
Background Steinernema carpocapsae are parasitic nematodes that invade and kill insects. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila and together form an excellent model to study pathogen infection processes and host anti-nematode/antibacterial immune responses. To determine the contribution of S. carpocapsae and their associated X. nematophila to the successful infection of insects as well as to investigate the interaction of each mutualistic partner with the insect immune system, it is important to develop and establish robust methods for generating nematodes devoid of their bacteria. Findings To produce S. carpocapsae nematodes without their associated X. nematophila bacteria, we have modified a previous method, which involves the use of a X. nematophilarpoS mutant strain that fails to colonize the intestine of the worms. We confirmed the absence of bacteria in the nematodes using a molecular diagnostic and two rounds of an axenicity assay involving appropriate antibiotics and nematode surface sterilization. We used axenic and symbiotic S. carpocapsae to infect Drosophila melanogaster larvae and found that both types of nematodes were able to cause insect death at similar rates. Conclusion Generation of entomopathogenic nematodes lacking their mutualistic bacteria provides an excellent tool to dissect the molecular and genetic basis of nematode parasitism and to identify the insect host immune factors that participate in the immune response against nematode infections.
Collapse
Affiliation(s)
- Shruti Yadav
- Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC, USA.
| | - Upasana Shokal
- Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC, USA.
| | - Steven Forst
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
| | - Ioannis Eleftherianos
- Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC, USA.
| |
Collapse
|
25
|
Deepa I, Kumar SN, Sreerag RS, Nath VS, Mohandas C. Purification and synergistic antibacterial activity of arginine derived cyclic dipeptides, from Achromobacter sp. associated with a rhabditid entomopathogenic nematode against major clinically relevant biofilm forming wound bacteria. Front Microbiol 2015; 6:876. [PMID: 26379651 PMCID: PMC4548193 DOI: 10.3389/fmicb.2015.00876] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 08/10/2015] [Indexed: 01/01/2023] Open
Abstract
Skin and chronic wound infections caused by various pathogenic bacteria are an increasing and urgent health problem worldwide. In the present investigation ethyl acetate extract of an Achromobacter sp. associated with a Rhabditis entomopathogenic nematode (EPN), displayed promising antibacterial property and was further purified by silica gel column chromatography to get three different cyclic dipeptides (CDPs). Based on the spectral data and Marfey's analyses, the CDPs were identified as cyclo(D-Leu-D-Arg) (1), cyclo(L-Trp-L-Arg) (2), and cyclo(D-Trp-D-Arg) (3), respectively. Three CDPs were active against all the 10 wound associated bacteria tested. The significant antibacterial activity was recorded by CDP 3, and highest activity of 0.5 μg/ml was recorded against Staphylococcus aureus and Pseudomonas aeruginosa. The synergistic antibacterial activities of CDPs and ampicillin were assessed using the checkerboard microdilution method. The results of the current study recorded that the combined effects of CDPs and ampicillin principally recorded synergistic activity. Interestingly, the combination of CDPs and ampicillin also recorded enhanced inhibition of biofilm formation by bacteria. Moreover, CDPs significantly stimulate the production of IL-10 and IL-4 (anti-inflammatory cytokines) by human peripheral blood mononuclear cells. CDPs do not make any significant effect on the production of pro-inflammatory cytokines like TNF-α. The three CDPs have been studied for their effect on intracellular S. aureus in murine macrophages (J774) using 24 h exposure to 0.5X, 1X, and 2X MIC concentrations. Significant decrease in intracellular S. aureus burden was recorded by CDPs. CDPs also recorded no cytotoxicity toward FS normal fibroblast, VERO, and L231 normal lung epithelial cell lines. Antimicrobial activity of the arginine containing CDPs against the wound associated bacteria is reported here for the first. Moreover, this is also the first report on the production of CDPs by Achromobacter sp. Finally, we conclude that the Achromobacter sp. is an incredibly promising source of natural bioactive secondary metabolites especially against wound pathogenic bacteria that may receive significant benefit in the field of human medicine in near future as topical agents.
Collapse
Affiliation(s)
- Indira Deepa
- Division of Crop Protection, Central Tuber Crops Research Institute Thiruvananthapuram, India
| | - Sasidharan N Kumar
- Division of Crop Protection, Central Tuber Crops Research Institute Thiruvananthapuram, India
| | - Ravikumar S Sreerag
- Division of Crop Protection, Central Tuber Crops Research Institute Thiruvananthapuram, India
| | - Vishnu S Nath
- Division of Crop Protection, Central Tuber Crops Research Institute Thiruvananthapuram, India
| | - Chellapan Mohandas
- Division of Crop Protection, Central Tuber Crops Research Institute Thiruvananthapuram, India
| |
Collapse
|
26
|
Peña JM, Carrillo MA, Hallem EA. Variation in the susceptibility of Drosophila to different entomopathogenic nematodes. Infect Immun 2015; 83:1130-8. [PMID: 25561714 PMCID: PMC4333445 DOI: 10.1128/iai.02740-14] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 12/29/2014] [Indexed: 12/11/2022] Open
Abstract
Entomopathogenic nematodes (EPNs) in the genera Heterorhabditis and Steinernema are lethal parasites of insects that are of interest as models for understanding parasite-host interactions and as biocontrol agents for insect pests. EPNs harbor a bacterial endosymbiont in their gut that assists in insect killing. EPNs are capable of infecting and killing a wide range of insects, yet how the nematodes and their bacterial endosymbionts interact with the insect immune system is poorly understood. Here, we develop a versatile model system for understanding the insect immune response to parasitic nematode infection that consists of seven species of EPNs as model parasites and five species of Drosophila fruit flies as model hosts. We show that the EPN Steinernema carpocapsae, which is widely used for insect control, is capable of infecting and killing D. melanogaster larvae. S. carpocapsae is associated with the bacterium Xenorhabdus nematophila, and we show that X. nematophila induces expression of a subset of antimicrobial peptide genes and suppresses the melanization response to the nematode. We further show that EPNs vary in their virulence toward D. melanogaster and that Drosophila species vary in their susceptibilities to EPN infection. Differences in virulence among different EPN-host combinations result from differences in both rates of infection and rates of postinfection survival. Our results establish a powerful model system for understanding mechanisms of host-parasite interactions and the insect immune response to parasitic nematode infection.
Collapse
Affiliation(s)
- Jennifer M Peña
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California, USA
| | - Mayra A Carrillo
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California, USA
| | - Elissa A Hallem
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, California, USA
| |
Collapse
|
27
|
Expression of prtA from Photorhabdus luminescens in Bacillus thuringiensis enhances mortality in lepidopteran larvae by sub-cutaneous but not oral infection. J Invertebr Pathol 2014; 121:85-8. [DOI: 10.1016/j.jip.2014.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/30/2014] [Accepted: 07/07/2014] [Indexed: 11/17/2022]
|
28
|
Kumar SN, Mohandas C, Nambisan B. Purification, structural elucidation and bioactivity of tryptophan containing diketopiperazines, from Comamonas testosteroni associated with a rhabditid entomopathogenic nematode against major human-pathogenic bacteria. Peptides 2014; 53:48-58. [PMID: 24120705 DOI: 10.1016/j.peptides.2013.09.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 09/28/2013] [Accepted: 09/30/2013] [Indexed: 10/26/2022]
Abstract
The cell free culture filtrate of a Comamonas testosteroni associated with an Entomopathogenic nematode (EPN), Rhabditis (Oscheius) sp. exhibited promising antimicrobial activity. The ethyl acetate extract of the bacterial culture filtrate was purified by silica gel column chromatography to obtain five diketopiperazines or cyclic dipeptides (DKP 1-5). The structure and absolute stereochemistry of the compounds were determined based on extensive spectroscopic analyses (HR-MS, (1)HNMR, (13)CNMR, (1)H-(1)H COSY, (1)H-(13)C HMBC) and Marfey's method. Based on the spectral data the compounds were identified as Cyclo-(L-Trp-L-Pro) (1), Cyclo-(L-Trp-L-Tyr) (2), Cyclo-(L-Trp-L-Ile) (3), Cyclo-(L-Trp-L-Leu) (4) and Cyclo-(L-Trp-L-Phe) (5), respectively. Three diketopiperazines (DKP 2, 3 and 5) were active against all the ten bacteria tested. The highest activity of 0.5μg/ml by Cyclo-(L-Trp-L-Phe) was recorded against Vibrio cholerae followed by Salmonella typhi (1 μg/ml) a human pathogen responsible for life threatening diseases like profuse watery diarrhea and typhoid or enteric fever. The activity of this compound against V. cholerae and S. typhi is more effective than ciprofloxacin and ampicillin, the standard antibiotics. Cyclo-(L-Trp-L-Phe) recorded significant antibacterial activity against all the test bacteria when compared to other compounds. Five diketopiperazines were active against all the test fungi and are more effective than bavistin the standard fungicide. Diketopiperazines recorded no cytotoxicity to FS normal fibroblast and VERO cells (African green monkey kidney) except DKP 3 and 4. To our best knowledge this is the first report of antimicrobial activity of the tryptophan containing diketopiperazines against the human pathogenic microbes. The production of cyclic dipeptides by C. testosteroni is also reported here for the first time. We conclude that the C. testosteroni is promising sources of natural bioactive secondary metabolites against human pathogenic bacteria which may receive great benefit in the field of human medicine in near future.
Collapse
Affiliation(s)
- S Nishanth Kumar
- Division of Crop Protection, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram 695017, India; Division of Crop Utilisation, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram 695017, India.
| | - C Mohandas
- Division of Crop Protection, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram 695017, India; Division of Crop Utilisation, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram 695017, India
| | - Bala Nambisan
- Division of Crop Protection, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram 695017, India; Division of Crop Utilisation, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram 695017, India
| |
Collapse
|
29
|
The genetic basis of the symbiosis between Photorhabdus and its invertebrate hosts. ADVANCES IN APPLIED MICROBIOLOGY 2014; 88:1-29. [PMID: 24767424 DOI: 10.1016/b978-0-12-800260-5.00001-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Photorhabdus is a pathogen of insects that also maintains a mutualistic association with nematodes from the family Heterorhabditis. Photorhabdus colonizes the gut of the infective juvenile (IJ) stage of the nematode. The IJ infects an insect and regurgitates the bacteria and the bacteria reproduce to kill the insect. The nematodes feed on the resulting bacterial biomass until a new generation of IJs emerges from the insect cadaver. Therefore, during its life cycle, Photorhabdus must (1) kill the insect host, (2) support nematode growth and development, and (3) be able to colonize the new generation of IJs. In this review, functional genomic studies that have been aimed at understanding the molecular mechanisms underpinning each of these roles will be discussed. These studies have begun to reveal that distinct gene sets may be required for each of these interactions, suggesting that there is only a minimal genetic overlap between pathogenicity and mutualism in Photorhabdus.
Collapse
|
30
|
Response of larval Ephestia kuehniella (Lepidoptera: Pyralidae) to individual Bacillus thuringiensis kurstaki toxins mixed with Xenorhabdus nematophila. J Invertebr Pathol 2013; 114:71-5. [DOI: 10.1016/j.jip.2013.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 02/26/2013] [Accepted: 05/28/2013] [Indexed: 11/22/2022]
|
31
|
Stoepler TM, Castillo JC, Lill JT, Eleftherianos I. A simple protocol for extracting hemocytes from wild caterpillars. J Vis Exp 2012. [PMID: 23183567 DOI: 10.3791/4173] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Insect hemocytes (equivalent to mammalian white blood cells) play an important role in several physiological processes throughout an insect's life cycle. In larval stages of insects belonging to the orders of Lepidoptera (moths and butterflies) and Diptera (true flies), hemocytes are formed from the lymph gland (a specialized hematopoietic organ) or embryonic cells and can be carried through to the adult stage. Embryonic hemocytes are involved in cell migration during development and chemotaxis regulation during inflammation. They also take part in cell apoptosis and are essential for embryogenesis. Hemocytes mediate the cellular arm of the insect innate immune response that includes several functions, such as cell spreading, cell aggregation, formation of nodules, phagocytosis and encapsulation of foreign invaders. They are also responsible for orchestrating specific insect humoral defenses during infection, such as the production of antimicrobial peptides and other effector molecules. Hemocyte morphology and function have mainly been studied in genetic or physiological insect models, including the fruit fly, Drosophila melanogaster, the mosquitoes Aedes aegypti and Anopheles gambiae and the tobacco hornworm, Manduca sexta. However, little information currently exists about the diversity, classification, morphology and function of hemocytes in non-model insect species, especially those collected from the wild. Here we describe a simple and efficient protocol for extracting hemocytes from wild caterpillars. We use penultimate instar Lithacodes fasciola (yellow-shouldered slug moth) (Figure 1) and Euclea delphinii (spiny oak slug) caterpillars (Lepidoptera: Limacodidae) and show that sufficient volumes of hemolymph (insect blood) can be isolated and hemocyte numbers counted from individual larvae. This method can be used to efficiently study hemocyte types in these species as well as in other related lepidopteran caterpillars harvested from the field, or it can be readily combined with immunological assays designed to investigate hemocyte function following infection with microbial or parasitic organisms.
Collapse
|
32
|
Castillo JC, Shokal U, Eleftherianos I. A novel method for infecting Drosophila adult flies with insect pathogenic nematodes. Virulence 2012; 3:339-47. [PMID: 22546901 DOI: 10.4161/viru.20244] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Drosophila has been established as an excellent genetic and genomic model to investigate host-pathogen interactions and innate immune defense mechanisms. To date, most information on the Drosophila immune response derives from studies that involve bacterial, fungal or viral pathogens. However, immune reactions to insect parasitic nematodes are still not well characterized. The nematodes Heterorhabditis bacteriophora live in symbiosis with the entomopathogenic bacteria Photorhabdus luminescens, and they are able to invade and kill insects. Interestingly, Heterorhabditis nematodes are viable in the absence of Photorhabdus. Techniques for infecting Drosophila larvae with these nematodes have been previously reported. Here, we have developed a method for infecting Drosophila adult flies with Heterorhabditis nematodes carrying (symbiotic worms) or lacking (axenic worms) their associated bacteria. The protocol we present can be readily adapted for studying parasitic strategies of other insect nematodes using Drosophila as the host infection model.
Collapse
Affiliation(s)
- Julio Cesar Castillo
- Insect Infection and Immunity Lab, Department of Biological Sciences, The George Washington University, Washington, DC, USA
| | | | | |
Collapse
|
33
|
Dobes P, Wang Z, Markus R, Theopold U, Hyrsl P. An improved method for nematode infection assays in Drosophila larvae. Fly (Austin) 2012; 6:75-9. [PMID: 22614785 PMCID: PMC3397922 DOI: 10.4161/fly.19553] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The infective juveniles (IJs) of entomopathogenic nematodes (EPNs) seek out host insects and release their symbiotic bacteria into their body cavity causing septicaemia, which eventually leads to host death. The interaction between EPNs and their hosts are only partially understood, in particular the host immune responses appears to involve pathways other than phagocytosis and the canonical transcriptional induction pathways. These pathways are genetically tractable and include for example clotting factors and lipid mediators. The aim of this study was to optimize the nematode infections in Drosophila melanogaster larvae, a well-studied and genetically tractable model organism. Here we show that two nematode species namely Steinernema feltiae and Heterorhabditis bacteriophora display different infectivity toward Drosophila larvae with the latter being less pathogenic. The effects of supporting media and IJ dosage on the mortality of the hosts were assessed and optimized. Using optimum conditions, a faster and efficient setup for nematode infections was developed. This newly established infection model in Drosophila larvae will be applicable in large scale screens aimed at identifying novel genes/pathways involved in innate immune responses.
Collapse
Affiliation(s)
- Pavel Dobes
- Department of Animal Physiology and Immunology, Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | | | | | | | | |
Collapse
|
34
|
An R, Voss M, Jagdale GB, Grewal PS. Differences in Immune Defense Evasion of Selected Inbred Lines of Heterorhabditis Bacteriophora in Two White Grub Species. INSECTS 2012; 3:378-89. [PMID: 26466530 PMCID: PMC4553597 DOI: 10.3390/insects3020378] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 03/01/2012] [Accepted: 03/14/2012] [Indexed: 12/05/2022]
Abstract
We determined virulence of seven Heterorhabditis bacteriophora strain GPS11 inbred lines possessing superior infective juvenile longevity, and heat and ultra violet radiation tolerance against white grubs Popillia japonica and Cyclocephala borealis. At 1 and 2 weeks after treatment, inbred line A2 was significantly more virulent towards P. japonica compared to the parent strain GPS11 and inbred lines A7, A8, A12 and A21; and line A2 caused significantly higher C. borealis mortality than lines A6 and A12. Penetration, encapsulation and survival of two inbred lines, A2 and A12, that showed the highest and lowest virulence against both grub species were then assessed. There were no differences between the two lines for the total number of nematodes penetrated in either P. japonica or C. borealis within the first 24 h, but a significantly higher percentage of penetrated nematodes were alive in line A2 compared to the line A12 in both grub species. P. japonica immune response over time to hemocoel-injected nematodes of A2, A12 and the parent strain was further investigated. While all injected nematodes were encapsulated at 6 h post injection, non-encapsulated living nematodes were detected at 12 and 24 h post injection, showing the breakage out of encapsulation. A higher percentage of non-encapsulated living nematodes and a lower percentage of dead nematodes were found in line A2 as compared to the line A12 after 12 h post injection. These data suggest that virulence differences in the studied H. bacteriophora inbred lines are not due to differences in nematode penetration or recognition by the grub immune system, but are related to the ability of the infective juveniles to break out of encapsulation.
Collapse
Affiliation(s)
- Ruisheng An
- Department of Entomology, Ohio State University, 1680 Madison Ave, Wooster, OH 44691, USA.
| | - Marcio Voss
- Embrapa Trigo, Passo Fundo, Rio Grande do Sul 99001-970, Brazil.
| | - Ganpati B Jagdale
- Department of Plant Pathology, University of Georgia, Athens, GA 30605, USA.
| | - Parwinder S Grewal
- Department of Entomology, Ohio State University, 1680 Madison Ave, Wooster, OH 44691, USA.
| |
Collapse
|
35
|
Insect immune responses to nematode parasites. Trends Parasitol 2011; 27:537-47. [PMID: 21982477 DOI: 10.1016/j.pt.2011.09.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 09/01/2011] [Accepted: 09/08/2011] [Indexed: 12/16/2022]
Abstract
Host innate immunity plays a central role in detecting and eliminating microbial pathogenic infections in both vertebrate and invertebrate animals. Entomopathogenic or insect pathogenic nematodes are of particular importance for the control of insect pests and vectors of pathogens, while insect-borne nematodes cause serious diseases in humans. Recent work has begun to use the power of insect models to investigate host-nematode interactions and uncover host antiparasitic immune reactions. This review describes recent findings on innate immune evasion strategies of parasitic nematodes and host cellular and humoral responses to the infection. Such information can be used to model diseases caused by human parasitic nematodes and provide clues indicating directions for research into the interplay between vector insects and their invading tropical parasites.
Collapse
|
36
|
Danchin A. A path from predation to mutualism. Mol Microbiol 2010; 77:1346-50. [PMID: 20860087 DOI: 10.1111/j.1365-2958.2010.07341.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Luminescent bacteria and nematodes associate in a strategy where the bacteria act as virulent pathogens of insects, used as their food supply, while the nematodes graze on them. Upon reaching high density, the bacteria produce light and metabolites that turn the nematodes into hosts permitting them to be carried over to further nematode preys. In this issue of Molecular Microbiology, Lango and Clarke show that the corresponding shift in lifestyle is triggered by a metabolic switch closely linked to the tricarboxylic acid cycle, but apparently not by the well-known acetate switch that monitors entry of bacteria into the stationary phase of growth.
Collapse
Affiliation(s)
- Antoine Danchin
- AMAbiotics SAS, Genavenir 8, 5 rue Henri Desbruères, 91030 Evry Cedex, France.
| |
Collapse
|