Identification and Characterization of a Symbiotic Bacterium Associated with Steinernema carpocapsae in Korea

Park, Youngjin; Kim, Yonggyun; Yi, Yanan

doi:10.1016/s1226-8615(08)60038-2

Cited by 42 publications

(27 citation statements)

References 14 publications

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“…temperata was isolated from an entomopathogenic nematode, H. megidis (13). X. nematophila was isolated from S. carpocapsae (25). Bacteria were cultured in Luria-Bertani (LB; Bacto tryptone, 10 g/liter; yeast extract, 5 g/liter; sodium chloride, 10 g/liter) medium for 48 h at 28°C on a shaking (200-rpm) incubator (JS-SKI-N900; Johnsam, Seoul, Republic of Korea).…”

Section: Methodsmentioning

confidence: 99%

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Phospholipase A ₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

Seo

Lee

Hong

et al. 2012

Appl Environ Microbiol

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109

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bThe entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata suppress insect immune responses by inhibiting the catalytic activity of phospholipase A 2 (PLA 2 ), which results in preventing biosynthesis of immune-mediating eicosanoids. This study identified PLA 2 inhibitors derived from culture broths of these two bacteria. Both X. nematophila and P. temperata subsp. temperata culture broths possessed significant PLA 2 -inhibitory activities. Fractionation of these bacterial metabolites in the culture broths using organic solvent and subsequent chromatography purified seven potent PLA 2 inhibitors, three of which (benzylideneacetone [BZA], proline-tyrosine [PY], and acetylated phenylalanine-glycine-valine [FGV]) were reported in a previous study. Four other compounds (indole, oxindole, cis-cyclo-PY, and p-hydroxyphenyl propionic acid) were identified and shown to significantly inhibit PLA 2 . X. nematophila culture broth contained these seven compounds, while P. temperata subsp. temperata culture broth contained three compounds (BZA, acetylated FGV, and cis-cyclo-PY). BZA was detected in the largest amount among these PLA 2 compounds in both bacterial culture broths. All seven bacterial metabolites also showed significant inhibitory activities against immune responses, such as phenoloxidase activity and hemocytic nodulation; BZA was the most potent. Finally, this study characterized these seven compounds for their insecticidal activities against the diamondback moth, Plutella xylostella. Even though these compounds showed relatively low toxicities to larvae, they significantly enhanced the pathogenicity of Bacillus thuringiensis. This study reports bacterial-origin PLA 2 inhibitors, which would be applicable for developing novel insecticides. Insect immune responses consist of innate cellular and humoral components (2). Upon pathogen infection, pattern recognition receptors recognize nonself and the recognition signal is transferred by immune mediators to effector tissues, such as hemocytes and fat body (7). Eicosanoids form a chemical group of oxygenated polyunsaturated C 20 fatty acids, which are derived from arachidonic acid, a catalytic product of phospholipase A 2 (PLA 2 ) on phospholipid (PL) substrate (3). Two types of eicosanoids, prostaglandins and leukotrienes, are known to mediate the nonself recognition signals against various insect pathogens, including bacteria, fungi, viruses, and parasitoid eggs in insects (38). Inhibition of PLA 2 prevents eicosanoid biosynthesis and suppresses immune responses in response to microbial pathogens (23, 37).Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata are insect pathogens that are symbiotic to the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis megidis, respectively (1, 13, 25). Infective juvenile-stage nematodes enter target insect hemocoel through natural openings (such as mouth, anus, and spiracles) and then release their symbiotic bacteria from the nematode intestine. The releas...

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Section: Methodsmentioning

confidence: 99%

“…temperata are insect pathogens that are symbiotic to the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis megidis, respectively (1,13,25). Infective juvenile-stage nematodes enter target insect hemocoel through natural openings (such as mouth, anus, and spiracles) and then release their symbiotic bacteria from the nematode intestine.…”

mentioning

confidence: 99%

Phospholipase A ₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

Seo

Lee

Hong

et al. 2012

Appl Environ Microbiol

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109

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“…After washing the bacterial cells three times with sterile phosphate-buffered saline (10 mM phosphate buffer with 0.8% NaCl, pH 7.4), the cells were suspended in 1 ml of PBS as already described (Park et al 1999). The suspended cells (10 μl; 10 8 cfu/ml) were used to assess the influence of bacterial cells on fat-body PLA2 activity.…”

Section: Methodsmentioning

confidence: 99%

“…nematophila is an extremely virulent insect pathogen. Infections of less than 40 bacterial cells are lethal to tobacco hornworms, Manduca sexta (Forst et al 1997) and beet armyworms, Spodoptera exigua (Park et al 1999). Part of the virulence is due to bacterial factors which inhibit insect immune reactions to infection.…”

Section: Introductionmentioning

confidence: 99%

The bacterium Xenorhabdus nematophila inhibits phospholipases A2 from insect, prokaryote, and vertebrate sources

Park

Kim

Stanley

2004

Naturwissenschaften

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The bacterium Xenorhabdus nematophila is a virulent insect pathogen. Part of its pathogenicity is due to impairing cellular immunity by blocking biosynthesis of eicosanoids, the major recognized signal transduction system in insect cellular immunity. X. nematophila inhibits the first step in eicosanoid biosynthesis, phospholipase A2 (PLA2). Here we report that the bacterium inhibits PLA2 from two insect immune tissues, hemocytes and fat body, as well as PLA2s selected to represent a wide range of organisms, including prokaryotes, insects, reptiles, and mammals. Our finding on a bacterial inhibitor of PLA2 activity contributes new insight into the chemical ecology of microbe-host interactions, which usually involve actions rather than inhibitors of PLA2s.

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“…The bacterium, X. nematophila, was isolated from the hemolymph of the fifth instar larvae of S. exigua infected with Steinernema carpocapsae collected in Pochon, Korea (Park et al, 1999). The bacteria were cultured in tryptic soy broth (TSB, Difco, USA) at 28°C for 48 h with 150 rpm.…”

Section: Bacteria and Insectsmentioning

confidence: 99%

An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits hemocytic phospholipase A2 (PLA2) in tobacco hornworms Manduca sexta

Park

Kim

Tunaz

et al. 2004

Journal of Invertebrate Pathology

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The entomopathogenic bacterium, Xenorhabdus nematophila, induces immunodepression in target insects and finally leads to lethal septicemia of the infected hosts. A hypothesis has been raised that the bacteria inhibit eicosanoid-biosynthesis pathway to interrupt immune signaling of the infected hosts. Here, we show direct evidence that X. nematophila inhibits the activity of phospholipase A2 (PLA2), the initial step in the eicosanoid-biosynthesis pathway. Inhibition of PLA2 was dependent on both incubation time with X. nematophila and the bacterial concentration in in vitro PLA2 preparations of Manduca sexta hemocytes. While living bacteria inhibited PLA2 activity, heat-killed X. nematophila rather increased PLA2 activity. X. nematophila secreted PLA2 inhibitor(s), which were detected in the organic, but not aqueous, extract of the bacterial culture medium. The PLA2 inhibitory activity of the organic extract was lost after heat treatment. These results clearly indicate that X. nematophila inhibits PLA2 activity and thereby inhibits eicosanoid biosynthesis, which leads to immunodepression of the infected hosts.

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Identification and Characterization of a Symbiotic Bacterium Associated with Steinernema carpocapsae in Korea

Cited by 42 publications

References 14 publications

Phospholipase A ₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

Phospholipase A ₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

The bacterium Xenorhabdus nematophila inhibits phospholipases A2 from insect, prokaryote, and vertebrate sources

An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits hemocytic phospholipase A2 (PLA2) in tobacco hornworms Manduca sexta

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Identification and Characterization of a Symbiotic Bacterium Associated with Steinernema carpocapsae in Korea

Cited by 42 publications

References 14 publications

Phospholipase A 2 Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

Phospholipase A 2 Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

The bacterium Xenorhabdus nematophila inhibits phospholipases A2 from insect, prokaryote, and vertebrate sources

An entomopathogenic bacterium, Xenorhabdus nematophila, inhibits hemocytic phospholipase A2 (PLA2) in tobacco hornworms Manduca sexta

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Phospholipase A ₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata

Phospholipase A ₂ Inhibitors Synthesized by Two Entomopathogenic Bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata