Effects of fat,choline and feeding regime on catalase gene expression in the liver of GIFT (Oreochromis niloticus)

Catalase is an enzyme that widely occurs in animals and plants. It is primarily used to decompose H₂O₂ in the body of animals to prevent oxidative damage to biological macromolecules. The present study investigated the influence of fat levels and feeding condition on the gene expression of catalase (CAT) in Genetically Improved Farmed Tilapia (GIFT) tilapia (Oreochromis niloticus). A full‐length 3063‐bp cDNA sequence, encoding 527 amino acid residues of CAT, was cloned, and the altered expression was assayed by real‐time polymerase chain reaction. The amino acid sequence shared high similarity with other animals (67%–92%). The fat and choline levels regulated the expression of CAT in the liver. When the fishes were fed 750 and 1,000 mg/kg choline, the expression of CAT in the liver increased initially and then decreased with increasing fat. The expression of CAT was maximum when 12% fat was fed; the feeding frequency and amount altered the expression of CAT. When fed two times a day, the expression in the liver first decreased to the minimum value with 8% body‐weight diets and then increased with the raised feed level. The results suggested that the expression of CAT gene in the liver of GIFT initially decreased and then increased with the raised level of feeding.