This study investigated the effect of Clostridium autoethanogenum protein (CaP) on intestinal absorption, antioxidant status, and immune response of the genetically improved farmed tilapia (GIFT: Oreochromis niloticus) juveniles. The fish (initial weight 0.7 ± 0.5 g) were fed with diets containing different levels of CaP: 0% (control), 5%, 10%, 15%, and 20% to partially replace soybean meal. After 8 weeks feeding trial, absorption capacity–related sodium/potassium-ATPase transporter (Na⁺/K⁺-ATP) was increased significantly by CaP levels; alkaline phosphatase (AKP) improved significantly by 5% and 10% CaP levels; while γ-glutamyl transpeptidase (γ-GT) was not significantly affected compared with the control diet. Malondialdehyde (MDA) content decreased significantly; glutathione (GSH) content and superoxide dismutase (SOD) activity increased significantly; while catalase (CAT) and glutathione peroxidase (GP-x) activities were not significantly affected by dietary CaP compared with the control. The expression of antioxidant-related genes: kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid-2-related factor 2 (Nrf2) and glutathione peroxidase (GPx) were significantly down-regulated, up-regulated by 5% and 10%, and not significantly affected by CaP levels compared with the control diet, respectively. The immune-related target of rapamycin (TOR), peptide transporter 1β (Pept 1β), complementary component 3 (C3) and interferon-gamma (IFN-γ) were significantly up-regulated by CaP levels; transforming growth factor-beta (TGF-β) was only significantly up-regulated by 5% and 10% CaP; while interleukin-8 (IL-8) was not significantly affected compared with the control. Therefore, our results show that dietary CaP could enhance the intestinal absorption, antioxidant status, and immune response in GIFT juveniles. However, inclusion levels above 10% could harm the intestinal histology of the fish.

中文翻译：

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膳食自产乙醇梭菌蛋白调节 GIFT (Oreochromis niloticus) 幼鱼的肠道吸收、抗氧化状态和免疫反应

本研究调查了自产乙醇梭菌蛋白 ( Ca P) 对转基因养殖罗非鱼 (GIFT: Oreochromis niloticus ) 幼鱼肠道吸收、抗氧化状态和免疫反应的影响。鱼（初始体重 0.7 ± 0.5 g）被喂食含有不同水平 CaP 的饮食：0%（对照）、5%、10%、15% 和 20% 以部分替代豆粕。经过 8 周的喂养试验，Ca P 水平显着增加了与吸收能力相关的钠/钾-ATP 酶转运蛋白 (Na ⁺ /K ⁺ -ATP) ；碱性磷酸酶 (AKP) 显着提高 5% 和 10% CaP级；而与对照饮食相比，γ-谷氨酰转肽酶（γ-GT）没有受到显着影响。丙二醛（MDA）含量显着下降；谷胱甘肽（GSH）含量和超氧化物歧化酶（SOD）活性显着增加；而与对照相比，过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GP-x）活性不受膳食钙磷的显着影响。抗氧化相关基因：kelch样ECH相关蛋白1（Keap1）、核因子红细胞2相关因子2（Nrf2）和谷胱甘肽过氧化物酶（GPx）表达显着下调，上调5%和 10%，并且不受Ca 的显着影响P 水平分别与对照饮食相比较。Ca P 水平显着上调雷帕霉素 (TOR)、肽转运蛋白 1β (Pept 1β)、互补成分 3 (C3) 和干扰素-γ (IFN-γ) 的免疫相关靶标；转化生长因子-β (TGF-β) 仅显着上调 5% 和 10% Ca P；而与对照相比，白细胞介素 8 (IL-8) 没有受到显着影响。因此，我们的结果表明，膳食钙磷可以增强 GIFT 幼鱼的肠道吸收、抗氧化状态和免疫反应。然而，超过 10% 的包含水平可能会损害鱼的肠道组织学。