title: Intra-tissue localization of an antibacterial L-amino acid oxidase in the rockfish Sebastes schlegeli.
abstract: The rockfish Sebastes schlegeli skin mucus contains a potent antibacterial protein, SSAP (S. schlegeli antibacterial protein), a novel l-amino acid oxidase with strict substrate specificity that acts against water-borne Gram-negative bacteria. We previously demonstrated that SSAP distributes in the skin and gills. Here we investigated the intra-tissue localization of SSAP in the tissues by in situ hybridization. Skin and gill sections were hybridized with digoxigenin-conjugated SSAP-specific RNA probe. SSAP mRNA-positive cells located near the basal membrane of skin epidermis and the gill epithelium. Furthermore, skin section was analyzed by immunohistochemistry and reacted with anti-SSAP antiserum as a primary antibody. The mucus layer and mucous cells in the skin were immunopositive. Skin and gill extracts produced hydrogen peroxide, responsible for antibacterial activity, in the presence of l-lysine. These results suggested that SSAP functions locally as a humoral defense factor in S. schlegeli skin and gills and prevents pathogenic bacterial invasion.
authors.affiliation: Department of Food Science and Technology, Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo 108-8477, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Kitani
authors.forename: Keiko
authors.initials: K
authors.lastname: Toyooka
authors.forename: Makoto
authors.initials: M
authors.lastname: Endo
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Ishizaki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagashima
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism; D029941:Fish Proteins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D005399:Fishes / Q000276:immunology* / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000276:immunology*; D050830:L-Amino Acid Oxidase / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D029941:Fish Proteins; D050830:L-Amino Acid Oxidase