부산대학교 도서관

We identified two lysozyme cDNA isoforms from starry flounder Platichthys stellate. The c-type and g-type starry flounder lysozyme cDNAs encoded polypeptides of 143 and 188 amino acids, respectively. Based on bioinformatic sequence characterizations, both isoforms possessed catalytic and other conserved residues essential for their functionality. Tissue distribution analysis revealed that c-type and g-type lysozyme transcripts were ubiquitously found in all tissue types examined. In particular, the c-type lysozyme mRNA was highly predominant in the spleen. On the other hand, g-type lysozyme transcripts were markedly detectable in posterior intestine, followed by kidney and spleen. In response to Streptococcus parauberis challenge, the splenic c-type, but not g-type, lysozyme mRNA level was significantly induced, indicating that the spleen is a major lysozyme producer in response to bacterial infection-mediated stress condition. At protein levels, the enhanced lysozyme activities in the skin mucus and serum were observed as early as 4 h post injection, suggesting that the lysozyme could be involved in the acute phase responses against bacterial infection. Taken together, our data indicate that S. parauberis infection elicits a lysozyme-associated systemic immune response in starry flounder, possibly in a tissue-specific and/or isoform-specific manner. [ABSTRACT FROM AUTHOR]