title: Functional analysis of C-type lysozyme in penaeid shrimp.
abstract: Lysozyme is an enzyme that cleaves the β-1,4-glycosidic linkages between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan, leading to bacterial lysis. Recently, lysozyme has been found to have anti-HIV and anti-cancer properties in mammals. However, most functional analyses were done in vitro using purified or recombinant lysozyme protein. Here, we used RNA interference to silence c-type lysozyme expression in penaeid shrimp, Marsupenaeus japonicus, to analyze the function of lysozyme in vivo. Silencing of lysozyme expression by dsRNA lysozyme (dsLYZ) led to 100% mortality without any artificial bacterial infection in 5 days. Lysozyme deficiency caused the number of hemocytes in hemolymph to decrease from 1.3 × 10(7) to 2.3 × 10(6) cells/ml and caused the number of bacteria to increase from 78 to 764 colony-forming units/ml. Suppression of bacterial growth using oxytetracycline and kanamycin showed improvement in mortality, suggesting that shrimp mortality post- dsLYZ injection can be attributed to bacterial growth in the shrimp hemolymph. The majority of the bacteria, identified by 16 S rRNA analysis, were Gram-negative species such as Vibrio and Pseudomonas. Furthermore, PKH26 staining showed that the dsLYZ-injected shrimp were unable to eliminate non pathogenic Escherichia coli or Staphylococcus aureus in 24 h. These data suggest that c-type lysozyme in shrimp serves to regulate the growth of bacterial communities, particularly Gram-negative bacteria, in the hemolymph.
authors: Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Minato, Konan 4-5-7, Tokyo 108-8477, Japan.
authors: Akihiro
authors: A
authors: Kaizu
authors: Fernand F
authors: FF
authors: Fagutao
authors: Hidehiro
authors: H
authors: Kondo
authors: Takashi
authors: T
authors: Aoki
authors: Ikuo
authors: I
authors: Hirono
mesh_terms: D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D020868:Gene Silencing; D006090:Gram-Negative Bacteria / Q000276:immunology / Q000378:metabolism; D016905:Gram-Negative Bacterial Infections / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D006434:Hemocytes / Q000201:enzymology* / Q000276:immunology; D006458:Hemolymph / Q000201:enzymology* / Q000276:immunology; D009113:Muramidase / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D033561:Penaeidae / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D013203:Staphylococcal Infections / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology / Q000378:metabolism
chemical_list: D060829:Arthropod Proteins; D009113:Muramidase