| 作者： |
Deng, Yu-Ping; Jiang, Wei-Dan; Liu, Yang; Qu, Biao; Jiang, Jun; Kuang, Sheng-Yao; Tang, Ling; Tang, Wu-Neng; Wu, Pei; Zhang, Yong-An; Zhou, Xiao-Qiu; Feng, Lin |
| 论文摘要： |
The objective of the study was to assess the influence of dietary leucine on flesh quality and the mRNA level of Nrf2-mediated antioxidant enzymes in the muscle of grass carp (Ctenopharyngodon idella). A total of 540 grass carp (295.85 +/- 2.07 g) were fed six diets with graded levels of leucine (7.1, 8.9, 11.0, 13.3, 15.2 and 17.1 g kg(-1) diet) for eight weeks. The result indicated that muscle protein, lipid content, muscle EAA (essential amino acid) levels, shear force, and hydroxyproline concentrationwere significantly improved by 11.0-17.1, 8.9-17.1, 8.9-17.1, 11.0-13.3, 8.9-13.3 g leucine kg(-1) diet supplementations, respectively. On the other hand, cooking loss, activities of cathepsin L, malondialdehyde and protein carbonyl contents exhibited an opposite tendency. Moreover, the results indicated that compared with leucine unsupplemented group (7.1 g leucine kg(-1) diet), 8.9-17.1, 11.0-17.1, 11.0-15.2 and 8.9-15.2 g kg(-1) leucine supplementations significantly enhanced the activities of copper/zinc superoxide dismutase (SOD1), catalase (CAT) and glutathione peroxidase (GPx), and glutathione content, respectively. Furthermore, the changes in the relative mRNA expressions of SOD1, CAT, GPx, nuclear factor erythroid 2-related factor 2 (Nrf2), target of rapamycin (TOR), and ribosomal protein S6 kinase beta-1 (S6K1) induced by leucine were similar to those noted in their enzyme activities. Conversely, the mRNA levels of Kelch-like ECH-associated protein 1 (Keap1) were significantly down-regulated by leucine supplementation. In conclusion, optimum leucine improved flesh quality, partly due to the enhancement of antioxidant capacity through regulating antioxidant-related signaling molecule. Based on muscle MDA, the optimum dietary leucine requirements of young grass carp (296-690 g) for flesh quality were estimated to be 12.8 g kg(-1) diet, corresponding to 39.3 g kg(-1) of dietary protein. (C) 2015 Elsevier B.V. All rights reserved. |
