The present study was conducted to investigate the roles of ascorbic acid (AA) in immune response, anti-oxidation and apoptosis in abalone (Haliotis discus hannai Ino). Seven semi-purified diets with graded levels of AA (0, 50, 100, 200, 500, 1000 and 5000 mg/kg) were fed to abalone (initial weight: 12.01 ± 0.001 g, initial shell length: 48.44 ± 0.069 mm) for 100 days. The survival, weight gain rate and daily increment in shell length were not affected by dietary AA. The AA content in the gill, muscle and digestive glands of abalone was significantly increased by dietary AA. In terms of immunity, dietary AA significantly improved the total hemocyte count, respiratory burst and phagocytic activity in hemolymph, and lysozyme activity in cell-free hemolymph (CFH). In the digestive gland, the TLR-MyD88-dependent and TLR-MyD88-independent signaling pathways were suppressed by dietary AA supplementation. The mRNA levels of β-defensin and arginase-I in the digestive gland were significantly increased by dietary AA. In the gill, only the TLR-MyD88-dependent signaling pathway was depressed by dietary AA to reduce inflammation in abalone. The level of mytimacin 6 in the gill was significantly upregulated by dietary AA. After Vibrio parahaemolyticus infection, the TLR signaling pathway in the digestive gland was suppressed by dietary AA, which reduced inflammation in the abalone. In terms of anti-oxidation, superoxide dismutase, glutathione peroxidase and catalase activities, as well as total anti-oxidative capacity and reduced glutathione content in CFH, were all significantly upregulated. The malondialdehyde content was significantly downregulated by dietary AA. The anti-oxidative capacity was improved by triggering the Keap1-Nrf2 pathway in abalone. In terms of apoptosis, dietary AA could enhance the anti-apoptosis ability via the JNK-Bcl-2/Bax signaling cascade in abalone. To conclude, dietary AA was involved in regulating immunity, anti-oxidation and apoptosis in abalone.

中文翻译：

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抗坏血酸调节鲍鱼的免疫、抗氧化和细胞凋亡

本研究旨在研究抗坏血酸 (AA) 在鲍鱼 ( Haliotis discus hannai ) 免疫反应、抗氧化和凋亡中的作用。井野）。将七种具有分级 AA 水平（0、50、100、200、500、1000 和 5000 毫克/千克）的半纯化饲料喂给鲍鱼（初始重量：12.01 ± 0.001 克，初始壳长：48.44 ± 0.069 毫米） 100 天。成活率、体重增加率和壳长的每日增量不受日粮 AA 的影响。鲍鱼鳃、肌肉和消化腺中的氨基酸含量因日粮氨基酸而显着增加。在免疫方面，膳食AA显着提高血淋巴中的总血细胞计数、呼吸爆发和吞噬活性，以及​​无细胞血淋巴（CFH）中的溶菌酶活性。在消化腺中，TLR-MyD88 依赖性和 TLR-MyD88 非依赖性信号通路受到膳食 AA 补充剂的抑制。β-防御素和精氨酸酶-I的mRNA水平消化腺中的 AA 显着增加。在鳃中，只有依赖于 TLR-MyD88 的信号通路被膳食 AA 抑制，以减少鲍鱼的炎症。日粮 AA 显着上调鳃中mytimacin 6的水平。后副溶血性弧菌在感染后，消化腺中的 TLR 信号通路被膳食 AA 抑制，从而减少了鲍鱼的炎症。在抗氧化方面，超氧化物歧化酶、谷胱甘肽过氧化物酶和过氧化氢酶活性，以及​​总抗氧化能力和 CFH 中谷胱甘肽含量的降低均显着上调。膳食AA显着下调丙二醛含量。通过触发鲍鱼中的 Keap1-Nrf2 通路来提高抗氧化能力。在细胞凋亡方面，日粮 AA 可以通过鲍鱼的 JNK-Bcl-2/Bax 信号级联增强抗细胞凋亡能力。综上所述，膳食AA参与鲍鱼免疫、抗氧化和凋亡的调节。