Molecular cloning and expression of two β-defensin and two mucin genes in common carp (Cyprinus carpio L.) and their up-regulation after β-glucan feeding

In this study, we described the partial structure, mRNA tissue distribution and regulation of two carp mucin and two β-defensin genes. This is the first description of these genes in fish. The genes might provide relevant tools to monitor feed-related improvements of fish health under aquaculture conditions. Carp mucin 2 and mucin 5B genes show a high similarity to their mammalian and avian counterparts. The carp β-defensin 1 and β-defensin 2 genes cluster together well with their piscine family members. The influence of a β-glucan immunomodulant on the expression of these genes in mucosal tissues could be confirmed for the first time. Muc5B expression was significantly increased in the skin. For Muc2 no significant up- or down-regulation could be observed. Significantly higher expression levels of β-defensin 2 in gills and both β-defensin genes in skin were found. Thus, the mucosal system can be influenced by the addition of β-glucans to the food.

► Two carp mucin genes were found and were highly similar to mammalian Muc2 and Muc5B.
► Muc2 was mostly expressed in intestine and Muc5B in skin.
► Two carp β-defensin genes were found which clustered well with BD1 and BD2.
► BD1 was found in skin and BD2 in liver.
► β-Glucan feeding increased expression of Muc5B, BD1, BD2 in skin and BD2 in gills.