The Role of phosphoenolpyruvate carboxykinase and reactive oxygen species in the

描述（由申请人提供）：地球上几乎所有的生物都有支持无氧代谢的基本代谢途径，然而许多生物，包括大多数脊椎动物，在没有分子氧的情况下无法长期生存。一年生泥鳅（Austrofundulus limnaeus）胚胎是研究脊椎动物缺氧耐受性和缺氧敏感性机制基础的良好模型。泥鳅的胚胎经历一个独特的发育休眠期，称为滞育。最近的证据表明，limnaeus的胚胎具有一些非常独特的生理适应，这些适应与长期缺氧的耐受性有关。在250℃的无氧环境下，冬眠和活跃发育的limnaeus胚胎都能存活数月。在缺氧暴露的最初几个小时内，limnaeus胚胎显示出ATP的大量消耗，并在同一时间内失去线粒体膜电位。这两个事件通常与其他脊椎动物细胞的细胞死亡有关，但海蛸的胚胎很快从线粒体生理和能量学的这些剧烈变化中恢复过来。这些观察结果表明，与其他脊椎动物相比，甚至与其他脊椎动物相比，limnaeus胚胎的细胞具有一些非凡的特征，这些特征表现出对缺氧的大量耐受性。我将确定在limnaeus分离细胞中支持缺氧耐受的代谢途径，评估缺氧和缺氧恢复期间线粒体功能和能量学，并验证由磷酸烯醇丙酮酸羧激酶支持的替代代谢途径对缺氧生存至关重要的假设。通过使用提案中概述的综合方法，我们有望对这种特殊的脊椎动物嗜极生物细胞中耐缺氧的细胞生理学有一个更完整的了解。

DESCRIPTION (provided by applicant): Almost all organisms on Earth share the basic metabolic pathways that support anaerobic metabolism, and yet many organisms, including most vertebrates, cannot survive for long without molecular oxygen. Embryos of the annual killifish Austrofundulus limnaeus are an excellent model for investigating the mechanistic basis of anoxia-tolerance and anoxia-sensitivity in vertebrates. Embryos of A. limnaeus undergo a unique period of developmental dormancy called diapause. Recent evidence suggests that embryos of A. limnaeus have some very unique physiological adaptations that are associated with tolerance of long-term anoxia. Both dormant and actively developing embryos of A. limnaeus can survive for months without oxygen at 250C. Embryos of A. limnaeus display a massive depletion of ATP during the initial hours of anoxic exposure and lose their mitochondrial membrane potential during this same time frame. These two events are typically associated with cell death in other vertebrate cells, but embryos of A. limnaeus quickly recover from these drastic changes in mitochondrial physiology and energetics. These observations imply that cells of A. limnaeus embryos have some extraordinary characteristics compared to other vertebrates, and even to other vertebrates that exhibit substantial tolerance of anoxia. I will identify the metabolic pathways that support anoxia tolerance in isolated cells of A. limnaeus, assess mitochondrial function and energetics during anoxia and recovery from anoxia, and test the hypothesis that an alternate metabolic pathways supported by the enzyme phosphoenolpyruvate carboxykinase is critical for the survival of anoxia. By using the integrative approaches outlined in the proposal we can hopefully create a more complete picture of the cellular physiology of anoxia-tolerance in the cells if this exceptional vertebrate extremophile.