Amino acids can act as signaling molecules in protein synthesis and animal growth by regulating several genes in the target of rapamycin (TOR) pathway. An 8-week feeding trial was conducted to examine the effects of dietary proline on growth performance, body composition, amino acid profiles, blood-biochemistry and expression of TOR pathway-related genes in juvenile Nibea diacanthus. Fish (450 juvenile N. diacanthus) were assigned to six dietary proline supplementation groups (0, 2.5, 5, 7.5, 10 and 12.5 g kg−1 of dry diet). The results revealed that the growth performance and feed utilization of N. diacanthus were not significantly improved with dietary proline level (P > 0.05). Whole-body crude protein and some amino acids in muscle tissue were significantly (P < 0.05) affected by the supplemental dietary proline, while the levels of hepatic GOT and GPT increased significantly (P < 0.05) with increasing levels of dietary proline. The transcript level of TOR in muscle was significantly affected by dietary proline level, while the mRNA levels of 4EBP, S6K1, TSC and GTPBP in muscle were relatively unaffected. In conclusion, our results indicate that (1) dietary proline promotes protein synthesis, and (2) proline may promote protein synthesis by regulating the transcription of TOR but not 4EBP, S6K1, TSC and GTPBP.

中文翻译：

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日粮脯氨酸对幼年斑鼓鲀幼鱼生长、生理、生化和TOR通路相关基因表达的影响

氨基酸可以通过调节雷帕霉素 (TOR) 通路靶标中的几个基因，在蛋白质合成和动物生长中充当信号分子。进行了一项为期 8 周的喂养试验，以检查膳食脯氨酸对幼年 Nibea diacanthus 生长性能、身体成分、氨基酸谱、血液生化和 TOR 通路相关基因表达的影响。将鱼（450 条幼年 N. diacanthus）分配到六个膳食脯氨酸补充组（0、2.5、5、7.5、10 和 12.5 g kg−1 干饲料）。结果表明，日粮脯氨酸水平对N. diacanthus 的生长性能和饲料利用率没有显着提高（P > 0.05）。补充膳食脯氨酸对全身粗蛋白和肌肉组织中的某些氨基酸有显着影响（P < 0.05），而肝脏 GOT 和 GPT 的水平随着膳食脯氨酸水平的增加而显着增加（P < 0.05）。肌肉中TOR的转录水平受膳食脯氨酸水平的显着影响，而肌肉中4EBP、S6K1、TSC和GTPBP的mRNA水平相对不受影响。总之，我们的结果表明（1）膳食脯氨酸促进蛋白质合成，（2）脯氨酸可能通过调节 TOR 而非 4EBP、S6K1、TSC 和 GTPBP 的转录来促进蛋白质合成。