Dietary sulfur amino acid modulations of taurine biosynthesis in juvenile turbot (Psetta maxima)

• Optimal dietary sulfur amino acids stimulated growth in turbot.
• The ability of taurine biosynthesis was investigated in turbot.
• Dietary Met and Cys stimulated hepatic cysteine dioxygenase.

Taurine is essential for development and homeostasis in various fish species. However, very limited information was available on the regulation of taurine biosynthesis in fish. In the present study, the effects of dietary sulfur amino acid supplementation on taurine biosynthesis were examined in juvenile turbot. Fish were fed with a casein-based semi-purified basal diet (CON) and diets supplemented with methionine at 0.5% (MM) and 1.5% (HM), cysteine at 0.3% (MC) and 0.6% (HC), or taurine at 1.5% (MT) and 2.5% (HT) separately, twice per day for 2 weeks. Growth performance, taurine concentration in multiple tissues, hepatic activities of cysteine dioxygenase (CDO) and cysteine sulfinic acid decarboxylase (CSD) were measured. Methionine, cysteine and taurine supplementations promoted growth performance in turbot. Methionine and cysteine supplementations stimulated hepatic CDO but not hepatic CSD activities. Dietary supplementation of methionine, cysteine and taurine increased taurine concentration in the liver. These results suggest the possibility that juvenile turbot has taurine biosynthesis capability, but may not be enough for its endogenous requirement.