| Research Abstract |
To analyze mode of action of immunostimulants such as b-1,3-glucans and sodium alginate, which have been reported to enhance biodefence of carp (Cyprinus carpio), genes of which expression was stimulated by the immunostimulants were identified by means of the suppression subtractive hybridization. As a result, about 50 genes including acute phase protein known in mammals, such as pentraxin and serum amyloid A, as well as several chemokines, chemokine-receptors, a novel C-type lectin, a novel complement factor B isotypes, glia-maturation factor, IL-1 beta, and pre-B cell enhancing factor were identified. Their complete primary structures were also determined from respective full-length cDNA clones, which were isolated from a carp leukocyte cDNA library. Interestingly, the b-1,3-glucan stimulated expression of a novel complement factor B isotype in carp kidney and spleen, suggesting a new role of factor B in bony fish. On the other hand, sodium alginate induced expression of chemokines and chemokine receptors, in agreement with the results that peritoneal injection of sodium alginate stimulated the migration of leukocytes from head kidney to peritoneal cavity. The present data suggests that each immunostimulant gave distinct pattern of gene expression in leukocytes and therefore, identification of the expressed genes gives an important insight into the mechanism of immunostimulants-mediated biodefense in bony fish. The approach in the present study would be useful to evaluate and to screen immunostimulants in bony fish.
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