Molecular identification of chitinase and its function in growth of Odontobutis potamophila

Abstract

Chitinases are pivotal enzymes for the degradation of chitin, which play a role in food digestion. However, the functional roles of chitinases in teleosts remain under-explored. In this study, a full-length cDNA of chitinase gene (namely, OpCht) was obtained from dark sleeper Odontobutis potamophila. The predicted amino acid sequence of OpCht consisted of a typical catalytic domain and a chitin-binding domain interconnected with a linker region. Phylogenetic analyses suggest that OpCht has appeared in the teleost-specific monophyletic branches (CHIO). Quantitative real-time PCR analyses showed that OpCht was mainly expressed in stomach, liver, intestine and increased significantly during the period of juvenile. The optimal gradient concentrations and intervals/efficiency of RNA interference (RNAi) in OpCht were established, the results demonstrated that RNAi significantly repressed the expression of OpCht and diminished the chitinase activity. After 8 weeks of long-term RNAi, knockdown of OpCht reduced the height of intestinal villus and the thickness of muscular layer, which led to a decline in weight gain rate (WGR), while the accompanying intestinal inflammation contributed to a decreased survival rate (SR) in O. potamophila. In conclusion, OpCht is implicated in chitin degradation and plays an important role in intestinal health and growth performance in O. potamophila.