Research Centre of the Ministry of Agriculture and Rural Affairs on Environmental Ecology and Fish Nutrition, Shanghai Ocean University, Shanghai, China.
School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Melbourne, VIC, Australia.
Front Immunol. 2022 Jul 19;13:913024. doi: 10.3389/fimmu.2022.913024. eCollection 2022.
The present study was conducted to investigate the effects of dietary inclusion of protein hydrolysates on growth performance, digestive enzyme activities, protein metabolism, and intestinal health in larval largemouth bass (). The experimental feeding trial presented in this study was based on five isonitrogenous and isolipidic diets formulated with graded inclusion levels of protein hydrolysates, and it showed that protein hydrolysates improved growth performance, reduced larval deformity rate, and increased the activity of digestive enzymes, including pepsin and trypsin. Gene expression results revealed that the supplementation of protein hydrolysates upregulated the expression of intestinal amino acid transporters LAT2 and peptide transporter 2 (PepT2), as well as the amino acid transporters LAT1 in muscle. Dietary provision of protein hydrolysates activated the target of rapamycin (TOR) pathway including the up-regulation of TOR and AKT1, and down-regulation of 4EBP1. Additionally, the expression of genes involved in the amino acids response (AAR) pathway, ATF4 and REDD1, were inhibited. Protein hydrolysates inhibited the transcription of some pro-inflammatory cytokines, including IL-8 and 5-LOX, but promoted the expression of anti-inflammatory cytokines TGF-β and IL-10. The 16S rRNA analysis, using V3-V4 region, indicated that dietary protein hydrolysates supplementation reduced the diversity of the intestine microbial community, increased the enrichment of and reduced the enrichment of at the genus level. In summary, protein hydrolysates have been shown to be an active and useful supplement to positively complement other protein sources in the diets for largemouth bass larvae, and this study provided novel insights on the beneficial roles and possible mechanisms of action of dietary protein hydrolysates in improving the overall performance of fish larvae.
本研究旨在探讨蛋白质水解物对幼期大口黑鲈生长性能、消化酶活性、蛋白质代谢和肠道健康的影响。本研究中的实验饲养试验基于五种等氮等脂的饲料，其中含有不同梯度水平的蛋白质水解物，结果表明蛋白质水解物可改善生长性能、降低幼鱼畸形率，并提高消化酶活性，包括胃蛋白酶和胰蛋白酶。基因表达结果显示，蛋白质水解物的添加可上调肠道氨基酸转运体 LAT2 和肽转运体 2（PepT2）以及肌肉中氨基酸转运体 LAT1 的表达。饲料中提供蛋白质水解物可激活雷帕霉素（TOR）途径的靶标，包括 TOR 和 AKT1 的上调以及 4EBP1 的下调。此外，还抑制了与氨基酸反应（AAR）途径相关的基因 ATF4 和 REDD1 的表达。蛋白质水解物抑制了一些促炎细胞因子（如 IL-8 和 5-LOX）的转录，但促进了抗炎细胞因子 TGF-β和 IL-10 的表达。使用 V3-V4 区的 16S rRNA 分析表明，饲料中添加蛋白质水解物可降低肠道微生物群落的多样性，增加 的富集，减少 的富集。综上所述，蛋白质水解物可作为一种有效的补充物，与其他蛋白质源在大口黑鲈幼鱼饲料中互补，本研究为饲料中蛋白质水解物在改善鱼类幼体整体性能方面的有益作用和可能的作用机制提供了新的见解。
