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The prophenoloxidase (proPO) activating system is an important innate immune response against microbial infections in invertebrates. The major enzyme, phenoloxidase (PO), is synthesized as an inactive precursor and its activation to an active enzyme is mediated by a cascade of clip domain serine proteinases (clip-SPs). In this study, a cDNA encoding a proPO(More)
Phenoloxidase (PO) plays an important role in arthropod melanization. Previously, a prophenoloxidase (PmproPO1) gene was cloned and characterized from the hemocytes of the black tiger shrimp, Penaeus monodon. In the present study, we report a novel proPO gene (PmproPO2) belonging to the proPO family identified from the P. monodon EST database(More)
The prophenoloxidase (proPO) activating system plays an important role in the defense against microbial invasion in invertebrates. In the present study, we report a second proPO-activating enzyme (designated PmPPAE2) from the hemocytes of the black tiger shrimp, Penaeus monodon. PmPPAE2 contained the structural features of the clip domain serine proteinase(More)
The clip domain serine proteinases (clip-SPs) play critical roles in the signaling processes during embryonic development and in the innate immunity of invertebrates. In the present study, we identified a homolog of the clip-SP, designated as PmClipSP1, by searching the Penaeus monodon EST database (http://pmonodon.biotec.or.th), and using RACE-PCR to(More)
The global shrimp industry still faces various serious disease-related problems that are mainly caused by pathogenic bacteria and viruses. Understanding the host defense mechanisms is likely to be beneficial in designing and implementing effective strategies to solve the current and future pathogen-related problems. Melanization, which is performed by(More)
The prophenoloxidase (proPO) system is activated upon recognition of pathogens by pattern recognition proteins (PRPs), including a lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP). However, shrimp LGBPs that are involved in the proPO system have yet to be clarified. Here, we focus on characterizing the role of a Penaeus monodon LGBP (PmLGBP) in(More)
Serine proteinases (SPs) participate in various biological processes and play vital role in immunity. In this study, we investigated the function of PmClipSP2 from shrimp Penaeus monodon in defense against bacterial infection. PmClipSP2 was identified as a clip-domain SP and its mRNA increased in response to infection with Vibrio harveyi.(More)
An important characteristic of the innate immune systems of crayfish and other arthropods is the activation of a serine proteinase cascade in the hemolymph, which results in the activation of prophenoloxidase and subsequently leading to the formation of toxic quinones and melanin. Although no true complement homologues have been detected in crayfish or(More)
Here we show that knockdown of laminin receptor (Lamr) with PvLamr dsRNA in the whiteleg shrimp Penaeus (Litopenaeus) vannamei (Pv) caused a dramatic reduction specifically in hyaline hemocytes prior to death. Since apoptosis was not detected in hemocytes or hematopoietic cells, other possible causes of hemocyte loss were investigated. Reports that(More)
The melanization cascade, activated by the prophenoloxidase (proPO) system, plays a key role in the production of cytotoxic intermediates, as well as melanin products for microbial sequestration in invertebrates. Here, we show that the proPO system is an important component of the Penaeus monodon shrimp immune defense toward a major viral pathogen, white(More)