Interaction of Xenorhabdus nematophilus subsp. nematophilus with the haemolymph of Galleria mellonella

Dunphy, Gary B.; Webster, John

doi:10.1016/0022-1910(84)90063-5

Cited by 78 publications

(46 citation statements)

References 19 publications

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“…The toxicity of entomopathogenic bacteria for insect hemocytes has already been described for Pseudomonas aeruginosa (26) and for X. nematophila (18,37,38). These in vivo experiments were inappropriate for distinguishing a direct toxicity of factors to hemocytes (cytotoxins) or a lytic action involving the general host physiology as with LPSs in mammals (36).…”

Section: Discussionmentioning

confidence: 88%

Two Distinct Hemolytic Activities in Xenorhabdus nematophila Are Active against Immunocompetent Insect Cells

Brillard¹,

Ribeiro²,

Boemare³

et al. 2001

Appl Environ Microbiol

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Xenorhabdus spp. and Photorhabdus spp. are major insect bacterial pathogens symbiotically associated with nematodes. These bacteria are transported by their nematode hosts into the hemocoel of the insect prey, where they proliferate within hemolymph. In this work we report that wild strains belonging to different species of both genera are able to produce hemolysin activity on blood agar plates. Using a hemocyte monolayer bioassay, cytolytic activity against immunocompetent cells from the hemolymph of Spodoptera littoralis (Lepidoptera: Noctuidae) was found only in supernatants of Xenorhabdus; none was detected in supernatants of various strains of Photorhabdus. During in vitro bacterial growth of Xenorhabdus nematophila F1, two successive bursts of cytolytic activity were detected. The first extracellular cytolytic activity occurred when bacterial cells reached the stationary phase. It also displayed a hemolytic activity on sheep red blood cells, and it was heat labile. Among insect hemocyte types, granulocytes were the preferred target. Lysis of hemocytes by necrosis was preceded by a dramatic vacuolization of the cells. In contrast the second burst of cytolytic activity occurred late during stationary phase and caused hemolysis of rabbit red blood cells, and insect plasmatocytes were the preferred target. This second activity is heat resistant and produced shrinkage and necrosis of hemocytes. Insertional inactivation of flhD gene in X. nematophila leads to the loss of hemolysis activity on sheep red blood cells and an attenuated virulence phenotype in S. littoralis (A. Givaudan and A. Lanois, J. Bacteriol. 182:107-115, 2000). This mutant was unable to produce the early cytolytic activity, but it always displayed the late cytolytic effect, preferably active on plasmatocytes. Thus, X. nematophila produced two independent cytolytic activities against different insect cell targets known for their major role in cellular immunity.

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Section: Discussionmentioning

confidence: 88%

Two Distinct Hemolytic Activities in Xenorhabdus nematophila Are Active against Immunocompetent Insect Cells

Brillard¹,

Ribeiro²,

Boemare³

et al. 2001

Appl Environ Microbiol

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“…In order to prevent the melanisation response, both Photorhabdus and Xenorhabdus appear to specifically inhibit phospolipase A 2 (PLA 2 ) resulting in inhibition of the eicosanoid pathway which controls haemocyte aggregation and nodulation by activation of the prophenoloxidase cascade [42][43][44][45]. In Xenorhabdus, LPS has been previously linked to inhibition of this cascade [46]. Recently two further systems for the inhibition of phenoloxidase have been discovered in Photorhabdus ssp.…”

Section: Evasion Of the Cellular Responsementioning

confidence: 99%

Overview of the Basic Biology of Bacillus thuringiensis with Emphasis on Genetic Engineering of Bacterial Larvicides for Mosquito Control

Federici¹

2013

TOTNJ

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Insect pathogens are an excellent source of novel insecticidal agents with proven toxicity. In particular, bacteria from the genera Photorhabdus and Xenorhabdus are proving to be a genomic goldmine, encoding a multitude of insecticidal toxins. Some are highly specific in their target species, whilst others are more generalist, but all are of potential use in crop protection against insect pests. These astounding bacterial species are also turning out to be equipped to produce a vast range of anti-microbial compounds which could be of use to medical science. This review will cover the current knowledge of the lifecycles of the two genera and the potential role of the toxins in their biology, before a more in depth exploration of some of the best studied toxins and their potential use in agriculture.

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“…The bacteria are carried into a susceptible insect larva by the nematode and are subsequently released into the insect hemolymph, where they participate in the killing of the insect host (3,4,11,17). X. nematophilus proliferates within the hemolymph and eventually enters stationary phase.…”

mentioning

confidence: 99%

“…The primary and secondary cells are equally pathogenic towards larvae of the greater wax moth, Galleria mellonella (17,25,31,46). The secondary cells of Xenorhabdus support growth and development of the nematodes in vitro (18,46).…”

mentioning

confidence: 99%

Inactivation of a Novel Gene Produces a Phenotypic Variant Cell and Affects the Symbiotic Behavior of Xenorhabdus nematophilus

Völgyi

Fodor

Forst

2000

Appl Environ Microbiol

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Xenorhabdus nematophilus is an insect pathogen that lives in a symbiotic association with a specific entomopathogenic nematode. During prolonged culturing, variant cells arise that are deficient in numerous properties. To understand the genetic mechanism underlying variant cell formation, a transposon mutagenesis approach was taken. Three phenotypically similar variant strains of X. nematophilus, each of which contained a single transposon insertion, were isolated. The insertions occurred at different locations in the chromosome. The variant strain, ANV2, was further characterized. It was deficient in several properties, including the ability to produce antibiotics and the stationary-phase-induced outer membrane protein, OpnB. Unlike wild-type cells, ANV2 produced lecithinase. The emergence of ANV2 from the nematode host was delayed relative to the emergence of the parental strain. The transposon in ANV2 had inserted in a gene designated var1, which encodes a novel protein composed of 121 amino acid residues. Complementation analysis confirmed that the pleiotropic phenotype of the ANV2 strain was produced by inactivation of var1. Other variant strains were not complemented by var1. These results indicate that inactivation of a single gene was sufficient to promote variant cell formation in X. nematophilus and that disruption of genetic loci other than var1 can result in the same pleiotropic phenotype.

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Interaction of Xenorhabdus nematophilus subsp. nematophilus with the haemolymph of Galleria mellonella

Cited by 78 publications

References 19 publications

Two Distinct Hemolytic Activities in Xenorhabdus nematophila Are Active against Immunocompetent Insect Cells

Two Distinct Hemolytic Activities in Xenorhabdus nematophila Are Active against Immunocompetent Insect Cells

Overview of the Basic Biology of Bacillus thuringiensis with Emphasis on Genetic Engineering of Bacterial Larvicides for Mosquito Control

Inactivation of a Novel Gene Produces a Phenotypic Variant Cell and Affects the Symbiotic Behavior of Xenorhabdus nematophilus

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