Eicosanoids mediate prophenoloxidase release from oenocytoids in the beet armyworm Spodoptera exigua

Shrestha, Sony; Kim, Yonggyun

doi:10.1016/j.ibmb.2007.09.013

Cited by 133 publications

(77 citation statements)

References 68 publications

(84 reference statements)

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“…Eicosanoids are required for inducing hemocyte melanization in S. exigua by activating PO precursor (36). Hemocyte nodule formation is a form of cellular immunity of S. exigua and accompanied by melanization reactions (23).…”

Section: Resultsmentioning

confidence: 99%

“…Catalytic activity of PLA 2 is required for biosynthesis of eicosanoids (5). Eicosanoids play a crucial role in insect immune responses by activating PO (36) or by stimulating migration of hemocytes to infection foci (20). Thus, inhibiting PLA 2 can prevent de novo supply of eicosanoids in response to pathogen infection, (28).…”

Section: Discussionmentioning

confidence: 99%

“…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 released bacteria suppress insect immune responses by inducing hemolysis, degrading antimicrobial peptides, suppressing prophenoloxidase activation, and inhibiting eicosanoid biosynthesis (17,36). Under immunosuppressive conditions, bacteria multiply and kill host insects.…”

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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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104

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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: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

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

Self Cite

104

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“…Phenoloxidase has potent anti-microbial properties, and its activation is tightly controlled within the hemolymph to prevent non-specific activation from harming the host (Jiravanichpaisal et al, 2006). PO activity in the hemolymph of Heliothis virescens larvae has been shown to have virucidal effects in vitro (Shelby & Popham, 2006) and previous research has supported the role of PO and cellular immunity in immune defenses against viruses (Stanley & Shapiro, 2007, 2009Shrestha & Kim, 2008). GLD is induced during encapsulation responses to pathogens (Cox-Foster & Stehr, 1994;Lee et al, 2005).…”

Section: Wwwintechopencommentioning

confidence: 96%

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

D’Amico¹,

Slavicek²

2012

Molecular Virology

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“…즉, 불활성 상태의 페놀옥시다제 전구물 질인 proPO가 PO로 활성화되는 과정에서 여러 종류의 serine proteases가 관여하게 된다 (Shrestha and Kim, 2007b). 이 과정에서 아이코사노이드류 가운데 프로스타 글란딘류가 혈구의 편도세포가 함유하고 있는 proPO를 세포붕괴과정을 통해 혈장으로 방출되게 하고, 이후 serine proteases에 의해 PO로 활성화된다는 아이코사노 이드류의 중개 기능이 밝혀졌다 (Shrestha and Kim, 2008). 활성화된 PO는 다양한 세포성 면역반응을 일으키 는 데 이용되게 된다.…”

Section: 담배나방 방제 약제의 쌀좀알벌 유충 발육과 성충 생존에 미치는 효과unclassified

Efficacy of an Integrated Biological Control of an Egg Parasitoid, Trichogramma evanescens Westwood, and Microbial Insecticide Against the Oriental Tobacco Budworm, Helicoverpa assulta (Guenée) Infesting Hot Pepper

Kim¹,

Heo²,

Park³

et al. 2008

Korean journal of applied entomology

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: Due to internal feeding behavior, the oriental tobacco budworm, Helicoverpa assulta (Guenée), infesting hot pepper has been regarded to be effectively controlled by targeting egg and neonate larval stages just before entering the fruits. This study aimed to develop an efficient biological control method focusing on these susceptible stages of H. assulta. An egg parasitoid wasp, Trichogramma evanescens Westwood, was confirmed to parasitize the eggs of H. assulta. A mixture of Gram-positive soil bacterium, Bacillus thuringiensis subsp. kurstaki, and Gram-negative entomopathogenic bacterium, Xenorhabdus nematophila ANU101, could effectively kill neonate larvae of H. assulta. A sex pheromone trap monitored the occurrence of field H. assulta adults. The microbial insecticide mixture was proved to give no detrimental effects on immature development and adult survival of the wasp by both feeding and contact toxicity tests. A combined treatment of egg parasitoid and microbial pesticide was applied to hot pepper fields infested by H. assulta. The mixture treatment of both biological control agents significantly decreased the fruit damage, which was comparable to the chemical insecticide treatment, though either single biological control agent did not show any significant control efficacy. This study also provides morphological and genetic characters of T. evanescens. KEY WORDS

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Eicosanoids mediate prophenoloxidase release from oenocytoids in the beet armyworm Spodoptera exigua

Cited by 133 publications

References 68 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

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

Efficacy of an Integrated Biological Control of an Egg Parasitoid, Trichogramma evanescens Westwood, and Microbial Insecticide Against the Oriental Tobacco Budworm, Helicoverpa assulta (Guenée) Infesting Hot Pepper

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Eicosanoids mediate prophenoloxidase release from oenocytoids in the beet armyworm Spodoptera exigua

Cited by 133 publications

References 68 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

Interactions Between Nucleopolyhedroviruses and Polydnaviruses in Larval Lepidoptera

Efficacy of an Integrated Biological Control of an Egg Parasitoid, Trichogramma evanescens Westwood, and Microbial Insecticide Against the Oriental Tobacco Budworm, Helicoverpa assulta (Guenée) Infesting Hot Pepper

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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