Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Fisheries, Immunology, Veterinary Sciences, Zoology, Lysozyme, Purification, Activity, Gene expression, Ivy, PliG, C-TYPE, MOLECULAR CHARACTERIZATION, ESCHERICHIA-COLI, LYTIC ACTIVITY, INHIBITOR, PURIFICATION, CLONING, CDNA, LOCALIZATION, SPECIFICITY, Animals, Blood Cells, Cations, Divalent, Cations, Monovalent, Cells, Cultured, Enzyme Activation, Fish Proteins, Gene Expression Profiling, Gene Expression Regulation, Gills, Head Kidney, Hot Temperature, Immunity, Innate, Lipopolysaccharides, Liver, Macrophages, Muramidase, Organ Specificity, Salmo salar, Spleen, 1107 Immunology, 3204 Immunology

Abstract:

Lysozymes represent important innate immune components against bacteria. In this study, Atlantic salmon (Salmo salar) goose (g-) and chicken (c-) types of lysozyme were subjected to protein characterisations and tissue expression analyses. Specific bacterial protein inhibitors of g- and c-type lysozymes were employed to discriminate between respective enzyme activities. Blood, gills and liver contained activities exclusive for the g-type lysozyme. Only haematopoietic organs (head kidney and spleen) contained enzyme activities of both g- and c-lysozyme enzymes and c-type activity was not found outside these organs. Gene transcript levels proportional to enzyme activity levels were detected for the g-type lysozyme but not for the c-type. In vitro studies revealed significant induction of c-type gene expression and enzyme activity in macrophages after incubation with lipopolysaccharide (LPS) while expression of the g-type lysozyme gene was unaffected. The activity of purified native c-type enzyme was profoundly reduced by divalent cations and displayed low tolerance to monovalent cations, while the native g-type lysozyme was stimulated by monovalent cations and tolerated low concentrations of divalent cations. Activities of both enzymes increased with temperature elevations up to 60°C. The native g-type lysozyme responses to temperature in particular are in apparent conflict to the ones for the recombinant salmon g-lysozyme. Our results imply separate expression regulations and different functions of c- and g-type lysozymes in salmon. LPS-induced expression of c-type lysozyme and broad constitutive tissue distribution of g-type lysozyme in salmon is different from findings in other studied fish species.