This study aimed to explore the effect exerted by oxidative stress on apoptosis-inducing factors (AIF)-mediated apoptosis and bovine muscle tenderness during postmortem aging. We investigated the reactive oxygen species (ROS) content, mitochondrial membrane permeability, AIF expression level, nucleus apoptosis, shear force, myofibril fragmentation index, pH, and energy level. According to the results, a rise in ROS content was accompanied by the rise in mitochondrial membrane permeability from 6 to 72 hr. In the meantime, the AIF expression in mitochondria was downregulated significantly within 72 hr. However, samples treated with N-acetylcysteine had significantly lower ROS content (6 to 72 hr) and mitochondrial membrane permeability (12 to 72 hr) than the control group. Moreover, during postmortem aging, the variations in AIF levels in mitochondria were closely associated with meat tenderization and nucleus apoptosis. These findings demonstrated that oxidative stress induced by ROS significantly promoted AIF release from mitochondria by enhancing the mitochondrial membrane permeability, and the released AIF mediated nucleus apoptosis that further enhanced bovine muscle tenderness. Besides, results suggest that in the early stage, the environmental factors (ATP content and pH) significantly decreased (0 to 72 hr), whereas ROS-induced oxidative stress had no significant effect on environmental factors. These observations further suggested that during postmortem aging, the decrease of pH and ATP consumption are required by AIF release. We conclude that ROS-induced oxidative stress and internal environment are vital for meat tenderization through the regulation of AIF-mediated apoptosis pathway. PRACTICAL APPLICATION: ROS-induced oxidative stress contributes to bovine muscle tenderization by promoting cell apoptosis. It is likely to lay a theoretical foundation for developing innovative tenderization techniques by altering the internal oxidation environment of postmortem muscles.

中文翻译：

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氧化应激对死后衰老过程中AIF介导的细胞凋亡和牛肌肉压痛的影响

本研究旨在探讨氧化应激对死后衰老过程中细胞凋亡诱导因子 (AIF) 介导的细胞凋亡和牛肌肉压痛的影响。我们研究了活性氧 (ROS) 含量、线粒体膜通透性、AIF 表达水平、细胞核凋亡、剪切力、肌原纤维碎裂指数、pH 值和能量水平。根据结果​​，ROS 含量的增加伴随着线粒体膜通透性从 6 小时增加到 72 小时。与此同时，线粒体中的 AIF 表达在 72 小时内显着下调。然而，与对照组相比，用 N-乙酰半胱氨酸处理的样品的 ROS 含量（6 至 72 小时）和线粒体膜通透性（12 至 72 小时）显着降低。此外，在死后衰老过程中，线粒体中AIF水平的变化与肉嫩化和细胞核凋亡密切相关。这些发现表明ROS诱导的氧化应激通过增强线粒体膜通透性显着促进AIF从线粒体中释放，释放的AIF介导细胞核凋亡，进一步增强牛肌肉柔软度。此外，结果表明，在早期，环境因素（ATP 含量和 pH 值）显着降低（0 至 72 小时），而 ROS 诱导的氧化应激对环境因素没有显着影响。这些观察进一步表明，在死后老化期间，AIF 释放需要降低 pH 值和 ATP 消耗。我们得出结论，ROS 诱导的氧化应激和内部环境通过调节 AIF 介导的细胞凋亡途径对肉嫩化至关重要。实际应用：ROS 诱导的氧化应激通过促进细胞凋亡促进牛肌肉嫩化。通过改变死后肌肉的内部氧化环境，可能为开发创新的嫩化技术奠定理论基础。