Hemolymph coagulation and phenoloxidase in larvae

Bidla, Gawa; Lindgren, Malin; Theopold, Ulrich; Dushay, Mitchell S.

doi:10.1016/j.dci.2004.11.007

Cited by 130 publications

(110 citation statements)

References 28 publications

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“…Entrapping of bacteria within the clots alone is not sufficient to kill them and requires bactericidal compounds among which some occur as intermediates during synthesis of melanin. 83 Because melanization of entrapped bacterial or fungal cells represents an efficient defense mechanism in insects, adapted pathogens should avoid excessive melanization caused by their secreted microbial metalloproteinases. Indeed, as a counter-adaptation to efficient mechanisms mediating both sensing of microbial metalloproteinases and activation of immune responses against their producers, entomopathogenic bacteria and fungi tightly regulate the activity of thermolysin.…”

Section: Coevolution Between Fungal Proteinases and Host Proteinase Imentioning

confidence: 99%

Coevolution between pathogen-derived proteinases and proteinase inhibitors of host insects

Vilcinskas¹

2010

Virulence

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Virulence is thought to coevolve as a result of reciprocal selection between pathogens and their hosts. This paper focuses on coevolution between microbial proteinases operating as virulence factors and host defense molecules of insects. Owing to shorter generation times and smaller genomes, microbes exhibit a high evolutionary adaptability in comparison with their hosts. Indeed, the latter can only compete with pathogens if they evolve mechanisms providing a comparable genetic plasticity. Gene or domain duplication and shuffling by recombination is the driving force behind the countermeasures in host defense effectors. Recent literature provides evidence for both diversifications of fungal proteinases involved in pathogenesis and expansion host proteinase inhibitors subsets contributing to insect innate immunity. For example, the pathogen-associated spectrum of proteolytic enzymes encompasses thermolysin-like metalloproteinases that putatively promoted the evolution of corresponding host inhibitors of these virulence factors which complement the insect repertoire of antimicrobial defense molecules. Beyond mutual diversification of effector molecules coevolution resulted also in sophisticated molecular adaptations of host insects such as sensing and feedback-loop regulation of microbial metalloproteinases and corresponding countermeasures of pathogens providing evasion of host immunity induced by these virulence factors

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Section: Coevolution Between Fungal Proteinases and Host Proteinase Imentioning

confidence: 99%

Coevolution between pathogen-derived proteinases and proteinase inhibitors of host insects

Vilcinskas¹

2010

Virulence

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“…1) (Ashida and Brey, 1997;Sugumaran, 2002;Nappi and Christensen, 2005). In vitro and in vivo studies demonstrated that PO generates quinones for melanogenesis (Jiang et al, 1997;De Gregorio et al, 2002a) and leads to changes in the physical properties of hemolymph clot through protein crosslinking (Bidla et al, 2005). Cuticle tanning (i.e.…”

Section: Introductionmentioning

confidence: 99%

Broad-spectrum antimicrobial activity of the reactive compounds generated in vitro by Manduca sexta phenoloxidase

Zhao

Wang

et al. 2007

Insect Biochemistry and Molecular Biology

168

109

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Although quinone production and melanin formation are widely recognized as an integral part of the insect defense system, experimental evidence is lacking that the proteolytic activation of prophenoloxidase participates in the direct killing of invading microbes-active phenoloxidase generates quinones that polymerize to form melanin. Here, we report the antimicrobial effect of reactive intermediates produced in phenoloxidase-catalyzed reactions. After being treated with Manduca sexta phenoloxidase and dopamine, Escherichia coli and Bacillus subtilis ceased to grow, whereas the growth of Pichia pastoris was slightly affected. Microscopic analysis showed melanin deposition on cell surface, aggregation of bacteria, and loss of cell mobility. Viability tests revealed major decreases in the bacterial colony counts and, since the decrease remained significant after dispersion of the cell clumps, the reactive compounds were surmised to have aggregated and killed E. coli and B. subtilis cells. Under the experimental conditions, 60-94% of the Gram-negative bacteria (E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella typhimurium) and 52-99% of the Gram-positive bacteria (Bacillus cereus, B. subtilis, Micrococcus luteus, and Staphylococcus aureus) were killed. In the presence of phenoloxidase, dopamine or 5,6-dihydroxyindole (DHI) exhibited much higher antibacterial activity than L-dopa, N-acetyldopamine (NADA) or N-β-alanyldopamine (NBAD) did, suggesting that DHI and its oxidation products were cytotoxic. The antifungal activity of DHI was detected using P. pastoris, Saccharomyces cerevisiae, Candida albicans, and Beauveria bassiana. These results established that prophenoloxidase activation is an integral component of the insect defense system involving a multitude of enzymes (e.g. proteinases, oxidases, and dopachrome conversion enzyme (DCE)), which immobilizes and kills invading microorganisms.

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“…Phenoloxidase has also been demonstrated to interfere with microbial infection in several insect species (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). In some cases melanization, or rather the activity of the enzyme PO, was found to have no or little impact on the killing/ clearance of parasites (24,25) and the melanization reaction was found not to be required for survival of mosquitoes/flies after certain microbial infections (26,27).…”

mentioning

confidence: 99%

Phenoloxidase Is an Important Component of the Defense against Aeromonas hydrophila Infection in a Crustacean, Pacifastacus leniusculus

Liu

Jiravanichpaisal

Cerenius

et al. 2007

Journal of Biological Chemistry

208

116

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The melanization cascade, in which phenoloxidase is the terminal enzyme, appears to play a key role in recognition of and defense against microbial infections in invertebrates. Here, we show that phenoloxidase activity and melanization are important for the immune defense toward a highly pathogenic bacterium, Aeromonas hydrophila, in the freshwater crayfish, Pacifastacus leniusculus. RNA interference-mediated depletion of crayfish prophenoloxidase leads to increased bacterial growth, lower phagocytosis, lower phenoloxidase activity, lower nodule formation, and higher mortality when infected with this bacterium. In contrast, if RNA interference of pacifastin, an inhibitor of the crayfish prophenoloxidase activation cascade, is performed, it results in lower bacterial growth, increased phagocytosis, increased nodule formation, higher phenoloxidase activity, and delayed mortality. Our data therefore suggest that phenoloxidase is required in crayfish defense against an infection by A. hydrophila, a highly virulent and pathogenic bacterium to crayfish.

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Hemolymph coagulation and phenoloxidase in larvae

Cited by 130 publications

References 28 publications

Coevolution between pathogen-derived proteinases and proteinase inhibitors of host insects

Coevolution between pathogen-derived proteinases and proteinase inhibitors of host insects

Broad-spectrum antimicrobial activity of the reactive compounds generated in vitro by Manduca sexta phenoloxidase

Phenoloxidase Is an Important Component of the Defense against Aeromonas hydrophila Infection in a Crustacean, Pacifastacus leniusculus

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