Cloning and expression of chitin deacetylase 1 from Macrobrachium nipponense, and the effects of dietary protein on growth, body composition and digestive enzymes

The optimal protein level in the diet of Oriental river prawn was investigated. Four isocaloric diets containing 300 g/kg, 360 g/kg, 420 g/kg, 480 g/kg crude protein (casein) were tested. Prawns fed 420 g/kg or 480 g/kg protein exhibited higher weight gain, specific growth rate, hepatopancreas somatic indices, feed coefficient and survival rate. Trypsin activity in the hepatopancreas increased with increasing dietary protein, with no significant difference between 420 g/kg and 480 g/kg groups (p < 0.05). Amylase, lipase and cellulase levels were comparable between groups (p > 0.05). Crude protein content in muscle increased with increasing dietary protein, with no significant difference between 420 g/kg and 480 g/kg diets (p > 0.05). There were no significant differences in moisture, crude fat or crude ash between groups. Essential amino acids lysine, tryptophan, phenylalanine, threonine, isoleucine, leucine and valine increased with increasing dietary protein, with no significant difference between 420 g/kg and 480 g/kg groups (p > 0.05). Total and essential amino acids increased with increasing dietary protein. Cloning of the full-length 2,435 bp Macrobrachium nipponense chitin deacetylase 1 (MnCDA1)gene revealed an open reading frame of 1,632 bp encoding a 535 residue polypeptide qPCR revealed highest expression in the hepatopancreas, followed by muscle, gill, heart and eyestalk. Expression in hepatopancreas and gill tissue, but not muscle, increased gradually with increasing dietary protein.