title: Factors functioning in nodule melanization of insects and their mechanisms of accumulation in nodules.
abstract: Nodules consisting of hemocytes and trapped microorganisms are important targets for melanization, which is best known in the insect immune system. We investigated factors functioning in nodule melanization and the mechanism by which these factors congregate in the nodule. BmHP21, BmSPH1 and BmSPH2, Bombyx mori orthologs of Manduca sexta serine protease HP21, serine protease homologs (SPH1 and SPH2), and a prophenoloxidase, BmPO1 were observed as inactive forms in the plasma, but as putatively active forms in the nodule. Production of prophenoloxidase-activating proteinases, BmPAP1 and BmPAP3/PPAE and BmPO1 were confirmed in hemocytes. BmSPH1 and BmSPH2 were observed on trapped bacterial cells in the nodule and were isolated from the surface of bacterial cells incubated with plasma. BmSPH1 and BmSPH2 were found in plasma in complex with a pattern recognition receptor, BmLBP. These data suggest that melanization-regulating factors congregate in nodules through a combination of microorganism-dependent and hemocyte-dependent routes.
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Tokura
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Gege Sun
authors.initials: GS
authors.lastname: Fu
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Sakamoto
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Endo
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Shiho
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kikuta
authors.affiliation: Department of Biological Production, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tabunoki
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan. Electronic address: ryoichi@cc.tuat.ac.jp.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Sato
mesh_terms: D000818:Animals; D012831:Bombyx / Q000235:genetics / Q000276:immunology*; D004156:Catechol Oxidase / Q000378:metabolism*; D004792:Enzyme Precursors / Q000378:metabolism*; D004926:Escherichia coli; D005260:Female; D006434:Hemocytes / Q000201:enzymology*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D018402:Manduca / Q000235:genetics; D008543:Melanins / Q000502:physiology*; D051379:Mice; D016982:Micrococcus luteus; D016133:Polymerase Chain Reaction
chemical_list: D004792:Enzyme Precursors; D019476:Insect Proteins; D008543:Melanins; C038451:pro-phenoloxidase; D004156:Catechol Oxidase
keywords: 4′,6-diamidino-2-phenylindole; B. mori multibinding protein; BmLBP; BmMBP; Bombyx mori; Bombyx mori lipopolysaccharide binding protein; DAPI; Innate immunity; Melanization; Nodule; PAP; PO; PPAE; Prophenoloxidase; ROS; SP; SPH; Serine protease homolog; phenoloxidase; proPO; proPO-activating enzyme; prophenoloxidase; prophenoloxidase-activating proteinase; reactive oxygen species; serine protease; serine protease homolog