Invertebrate Dormancy: Mechanisms of Metabolic and Biosynthetic Arrest

自然界中有很多动物会抑制新陈代谢，进入休眠状态，以应对次优的环境条件。这样的新陈代谢反应似乎需要对能量产生途径和生物合成、能量利用过程进行协调抑制。本研究的目的之一是确定卤虫胚胎在厌氧休眠期间蛋白质生物合成和分解代谢途径同时停止但又独立的机制。蛋白质合成的调节将在细胞质以及线粒体内的隔室中进行检测。相同的细胞内信号(酸性细胞内pH)可能直接或间接地介导合成代谢和分解代谢途径的停止，而大分子降解的速度可能最终限制休眠的持续时间。其次，将研究细胞内溶质在细胞脱水过程中破坏代谢组织的重要性。第三，研究将针对了解卤虫胚胎滞育期间发育和代谢停滞的性质。这些研究中使用的方法将包括同步微量热法-呼吸测量法，一种用于量化蛋白质合成的细胞自由翻译系统，胚胎的通透性，以及分离细胞器的体外研究。这些研究的结果应该适用于由于干燥、缺氧和极端温度而经历压力的各种生物系统，或者一般情况下，对于任何已知发生生物合成和能量代谢急剧调节的组织或细胞。//

There are widespread examples of animals in nature that suppress metabolism and enter dormant states in response to suboptimal environmental conditions. Such a metabolic response would seem to require coordinated suppression of both energy-producing pathways and biosynthetic, energy-utilizing processes. One objective of the proposed studies is to identify the mechanisms responsible for the simultaneous, yet independent, arrest of protein biosynthesis and of catabolic pathways during anaerobic dormancy in embryos of the brine shrimp Artemia. Regulation of protein synthesis will be examined in the cytoplasmic as well as the intramitochondrial compartments. The same intracellular signal (acidic intracellular pH) may directly or indirectly mediate arrest of anabolic and catabolic pathways, and that rates of macromolecular degradation may ultimately limit the duration of dormancy. Secondly, the importance of intracellular solutes in disrupting metabolic organization during cellular dehydration will be studied. Thirdly, studies will be directed toward understanding the nature of developmental and metabolic arrest during diapause in Artemia embryos. Methods employed in these studies will include simultaneous microcalorimetry-respirometry, a cell free translation system for quantifying protein synthesis, permeabilization of embryos, and in vitro studies with isolated organelles. Results of these studies should have implication for a variety of biological systems that experience stress as a result of desiccation, oxygen deprivation an temperature extremes, or in general, for any tissue or cell where acute modulation of biosynthesis and energy metabolism is known to occur. //