Physico-chemical properties and mode of action of a signal from the symbiotic bacterium Photorhabdus luminescens inducing dauer juvenile recovery in the entomopathogenic nematode Heterorhabditis bacteriophora

Nematology ◽  
2001 ◽  
Vol 3 (8) ◽  
pp. 849-853 ◽  
Author(s):  
Ralf-Udo Ehlers ◽  
Jens Aumann
Keyword(s):  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Chemical Properties ◽  
Symbiotic Bacterium ◽  
Heterorhabditis Bacteriophora ◽  
Juvenile Stage ◽  
Food Sources ◽  
Symbiotic Bacteria ◽  
Photorhabdus Luminescens ◽  
Physico Chemical

AbstractRecovery in entomopathogenic nematodes is the exit from the dauer juvenile stage. It is a response to environmental queues signalling the presence of food sources (e.g., insect haemolymph). The bacterium Photorhabdus luminescens excretes a signal which also induces recovery of its symbiotic Heterorhabditis bacteriophora dauer juveniles. This bacterial signal is composed of at least two compounds with different polarity. The symbiotic bacteria also secrete an antagonistic signal which inhibits nematode recovery. The recovery-inducing signal compounds have a molecular mass of less than 20 kDa and are negatively charged. The data indicate that at least one compound is smaller than 5 kDa. The bacterial signal triggers by receptor binding, the first step in a recovery-inducing muscarinic signalling pathway.

scholarly journals The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis

2021 ◽  
Author(s):  
Mengyi Cao ◽  
Hillel T. Schwartz ◽  
Chieh-Hsiang Tan ◽  
Paul W. Sternberg
Keyword(s):  
Entomopathogenic Nematodes ◽  
Genetic Model ◽  
Entomopathogenic Nematode ◽  
Model Development ◽  
Symbiotic Bacteria ◽  
Mutualistic Symbiosis ◽  
Self Fertilization ◽  
Rapid Generation ◽  
Mutant Lines

AbstractEntomopathogenic nematodes, including Heterorhabditis and Steinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (Photorhabdus and Xenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in entomopathogenic nematodes has been impeded by limited genetic tractability, inconsistent growth in vitro, variable cryopreservation, and low mating efficiency. We obtained the recently described Steinernema hermaphroditum strain CS34 and optimized its in vitro growth, with a rapid generation time on a lawn of its native symbiotic bacteria Xenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously, S. hermaphroditum isolated from insect hosts was described as first-generation hermaphroditic and second-generation gonochoristic. We discovered that CS34, when grown in vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens in S. hermaphroditum that produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report that S. hermaphroditum CS34 is the first consistently hermaphroditic entomopathogenic nematode and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.

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

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

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

Isolation, bioassay and characterisation of Xenorhabdus sp. SY5, a highly virulent symbiotic bacterium of an entomopathogenic nematode isolated from China

Nematology ◽  
2013 ◽  
Vol 15 (2) ◽  
pp. 153-163 ◽  
Author(s):  
Huan Wang ◽  
Hui Dong ◽  
Haitao Qian ◽  
Runxi Xia ◽  
Bin Cong
Keyword(s):  
Growth Inhibition ◽  
Insecticidal Activity ◽  
Entomopathogenic Nematode ◽  
Symbiotic Bacterium ◽  
Symbiotic Bacteria ◽  
Toxin Gene ◽  
Agricultural Pests ◽  
Bacterial Strains ◽  
Biological Pest Control ◽  
Highly Virulent

The entomopathogenic nematodes (EPN), together with their symbiotic bacteria, are obligate and lethal parasites of insects and are applied as biological approaches to pest management. In this paper, we isolated 122 strains of symbiotic bacteria from 23 EPN isolates that were gathered in various soils containing different vegetations from different regions of China. All these isolated bacterial strains showed oral insecticidal activity and/or growth inhibition to the larvae of Ostrinia furnacalis. Among these strains, Xenorhabdus sp. SY5 exhibited high insecticidal activity to O. furnacalis, Plutella xylostella, Mythimna separata, Laphygma exigua and Tenebrio molitor, all of which are important agricultural pests. Xenorhabdus sp. SY5 was isolated from EPN Steinernema sp. SY5. Through DEAE-52 column chromatography, seven toxins were purified from X. sp. SY5. Bioassay results showed that all seven toxins had, to a certain extent, insecticidal activity and/or growth inhibition to O. furnacalis, T. molitor, P. xylostella, M. separata and L. exigua. Our data also showed that each of these toxins had different insecticidal activity and/or growth inhibition against different insect species. The partial toxin gene sequence of X. sp. SY5 was determined, and its deduced amino acid sequence only showed 75, 66 and 65% identities to homologues of EPN symbiotic bacteria Photorhabdus luminescens, Xenorhabdus nematophila and Yersinia mollaretii, respectively. These results suggested that strain SY5 is a highly virulent EPN symbiotic bacterial strain that has a potential value for biological pest control.

Analysis of two isolates of a Heterorhabditis bacteriophora population detected in Córdoba, Argentina

Nematology ◽  
2000 ◽  
Vol 2 (4) ◽  
pp. 473-476
Author(s):  
María Bertolotti ◽  
Gladys De Sousa ◽  
Mónica Valenzuela ◽  
María M.A. De Doucet
Keyword(s):  
Soil Sample ◽  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Heterorhabditis Bacteriophora ◽  
Symbiotic Bacteria ◽  
Taxonomic Character ◽  
Morphometric Characters ◽  
Isozyme Patterns ◽  
Taxonomic Studies

AbstractEntomopathogenic nematodes of the genus Heterorhabditis are associated with symbiotic bacteria Photorhabdus spp. (Enterobacteriaceae). Taxonomic studies confirm that each species of nematode has a specific natural association with only one species of bacterium (Boemare & Doucet, 1996). Except in a few cases, the bacteria change the colour of the parasitized insect to different reddish tones and produce bioluminescence (Grimont et al., 1984; Boemare & Doucet, 1996). These distinct colours would be assumed to be due to the different species of Photorhabdus and, consequently, to indicate different species of Heterorhabditis. Therefore, the colour of the cadaver has been used as a taxonomic character (Stock, 1993). In a single soil sample from Córdoba City, Argentina, two isolates of Heterorhabditis were found that were clearly distinguished by the colour of the parasitized Galleria mellonella larva: isolate A, violet-brown; B, reddish. These different phenotypes led us to suppose that the nematode isolates were associated with different symbiotic bacteria and that the nematodes were different species. The purposes of this work were: to establish the identity of the isolates and to compare them on the basis of morphological and morphometric characters, and isozyme patterns.

Diversity of entomopathogenic nematodes and their symbiotic bacteria in south African plantations and indigenous forests

Nematology ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 355-371 ◽  
Author(s):  
Birhan A. Abate ◽  
Bernard Slippers ◽  
Michael J. Wingfield ◽  
Antoinette P. Malan ◽  
Brett P. Hurley
Keyword(s):  
South Africa ◽  
South African ◽  
Dna Sequences ◽  
Entomopathogenic Nematodes ◽  
Nematode Species ◽  
Symbiotic Bacteria ◽  
Photorhabdus Luminescens ◽  
Time Analysis ◽  
Forestry Plantations ◽  
First Time

Summary The occurrence and diversity of entomopathogenic nematodes (EPN) and their symbiotic bacteria was evaluated in commercial forestry plantations (Eucalyptus spp., Pinus spp. and Acacia mearnsii) and indigenous forests in South Africa. EPN were most prevalent in A. mearnsii plantations, accounting for 60.7% of the isolates, while indigenous forests, plantations of Pinus spp. and Eucalyptus spp. accounted for 35.7, 3.6 and 0% of the isolates, respectively. DNA sequences of the internal transcribed spacer (ITS) and D2-D3 28S rDNA regions were used to identify the nematode species. Four Steinernema spp. were identified, including S. citrae, S. sacchari, two undescribed species, as well as Heterorhabditis bacteriophora and H. baujardi. Heterorhabditis baujardi is reported from South Africa for the first time. Analysis of 16S rRNA of the bacteria confirmed the presence of at least three Xenorhabdus species from Steinernema isolates and two subspecies of Photorhabdus luminescens from Heterorhabditis species.

Photorhabdus luminescens subsp. noenieputensis subsp. nov., a symbiotic bacterium associated with a novel Heterorhabditis species related to Heterorhabditis indica

2013 ◽  
Vol 63 (Pt_5) ◽  
pp. 1853-1858 ◽  
Author(s):  
Tiarin Ferreira ◽  
Carol van Reenen ◽  
Sylvie Pagès ◽  
Patrick Tailliez ◽  
Antoinette P. Malan ◽  
...  
Keyword(s):  
Type Species ◽  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Symbiotic Bacterium ◽  
Tween 20 ◽  
Haemolytic Activity ◽  
Phenotypic Traits ◽  
Photorhabdus Luminescens ◽  
Content Type ◽  
Link Type

The bacterial symbiont AM7T, isolated from a novel entomopathogenic nematode species of the genus Heterorhabditis, displays the main phenotypic traits of the genus Photorhabdus and is highly pathogenic to Galleria mellonella. Phylogenetic analysis based on a multigene approach (16S rRNA, recA, gyrB, dnaN, gltX and infB) confirmed the classification of isolate AM7T within the species Photorhabdus luminescens and revealed its close relatedness to Photorhabdus luminescens subsp. caribbeanensis , P. luminescens subsp. akhurstii and P. luminescens subsp. hainanensis . The five concatenated protein-encoding sequences (4197 nt) of strain AM7T revealed 95.8, 95.4 and 94.9 % nucleotide identity to sequences of P. luminescens subsp. caribbeanensis HG29T, P. luminescens subsp. akhurstii FRG04T and P. luminescens subsp. hainanensis C8404T, respectively. These identity values are less than the threshold of 97 % proposed for classification within one of the existing subspecies of P. luminescens . Unlike other strains described for P. luminescens , strain AM7T produces acid from adonitol, sorbitol and xylitol, assimilates xylitol and has no lipase activity on medium containing Tween 20 or 60. Strain AM7T is differentiated from P. luminescens subsp. caribbeanensis by the assimilation of N-acetylglucosamine and the absence of haemolytic activity. Unlike P. luminescens subsp. akhurstii , strain AM7T does not assimilate mannitol, and it is distinguished from P. luminescens subsp. hainanensis by the assimilation of trehalose and citrate, the inability to produce indole from tryptophan and the presence of acetoin production and urease activity. Strain AM7T ( = ATCC BAA-2407T  = DSM 25462T) belongs to a novel subspecies, and is proposed as the type strain of Photorhabdus luminescens subsp. noenieputensis sp. nov.

scholarly journals The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis

Genetics ◽  
2021 ◽  
Author(s):  
Mengyi Cao ◽  
Hillel T Schwartz ◽  
Chieh-Hsiang Tan ◽  
Paul W Sternberg
Keyword(s):  
Entomopathogenic Nematodes ◽  
Genetic Model ◽  
Entomopathogenic Nematode ◽  
Model Development ◽  
Symbiotic Bacteria ◽  
Mutualistic Symbiosis ◽  
Self Fertilization ◽  
Rapid Generation ◽  
Mutant Lines

Abstract Entomopathogenic nematodes, including Heterorhabditis and Steinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (Photorhabdus and Xenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in entomopathogenic nematodes has been impeded by limited genetic tractability, inconsistent growth in vitro, variable cryopreservation, and low mating efficiency. We obtained the recently described Steinernema hermaphroditum strain CS34 and optimized its in vitro growth, with a rapid generation time on a lawn of its native symbiotic bacteria Xenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously, S. hermaphroditum isolated from insect hosts was described as producing hermaphrodites in the first generation. We discovered that CS34, when grown in vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens in S. hermaphroditum that produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report that S. hermaphroditum CS34 is the first consistently hermaphroditic entomopathogenic nematode and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.

Sign in / Sign up

Export Citation Format

Share Document