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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抗坏血酸调节鲍鱼免疫、抗氧化和细胞凋亡


本研究旨在探讨抗坏血酸（AA）在鲍鱼（ Haliotis diskus hannai Ino）免疫反应、抗氧化和细胞凋亡中的作用。将 7 种 AA 分级水平（0、50、100、200、500、1000 和 5000 mg/kg）的半纯化饲料喂给鲍鱼（初始重量：12.01 ± 0.001 g，初始壳长：48.44 ± 0.069 mm） 100 天。存活率、增重率和壳长日增量不受日粮 AA 的影响。饲料中添加AA显着提高了鲍鱼鳃、肌肉和消化腺中的AA含量。在免疫方面，膳食AA显着提高了血细胞总数、呼吸爆发和血淋巴中的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，膳食 AA 补充剂可抑制 TLR-MyD88 依赖性和 TLR-MyD88 独立信号通路。膳食AA显着增加了消化腺中β-防御素和精氨酸酶-I的mRNA水平。在鳃中，只有 TLR-MyD88 依赖性信号通路被膳食 AA 抑制，从而减少鲍鱼的炎症。膳食 AA 显着上调了鳃中的丝霉星 6水平。副溶血弧菌感染后，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​​CFH中的总抗氧化能力和还原型谷胱甘肽含量均显着上调。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，膳食AA可以通过JNK-Bcl-2/Bax信号级联增强鲍鱼的抗细胞凋亡能力。总之，膳食AA参与调节鲍鱼的免疫、抗氧化和细胞凋亡。