Energetics of Protein Metabolism during Development of Antarctic Echinoderms

[130398]海洋环境中无脊椎动物的生活史策略以幼虫形式为主。在南极洲，能量收支计算表明，棘皮动物的幼虫阶段有能力在没有食物的情况下存活数月至数年。这导致了一种猜测，即这些幼虫形式的能量代谢机制更有效，这种“增强的效率”可能是极端寒冷环境下的生命所独有的。近年来对南极海洋无脊椎动物发育生理生化基础的研究揭示了低温环境下代谢的一些新方面。与预期的低温条件下的低代谢和低大分子合成率相反，南极海胆的胚胎和幼虫在保持低代谢率的同时具有高蛋白质合成率。最近的一项发现解决了这个明显的矛盾，即这种南极海胆合成蛋白质的成本是其他动物的二十五分之一。这是动物蛋白质合成的最高效率，对寒冷环境下的生长发育具有重要的生理学意义。这种独特的蛋白质合成的生化效率是当前项目详细研究的主题。研究小组将结合南极幼虫生理学和生物化学以及海胆发育的分子生物学方面的专业知识，以解决基于三个主要目标的实验计划。(1)南极海胆幼虫蛋白质合成成本较低这一最新发现的普遍性，将通过测量南极其他棘皮动物发育过程中的代谢和蛋白质合成来验证。(2)对高蛋白质合成率和低代谢成本的预测表明，这种生物的生长效率将很高。这将通过测量幼虫蛋白质生长效率的生理学来检验。(3)利用特定的分子生物学方法研究南极海胆胚胎独特的高效蛋白质合成。这些定量分析的结合将使我们能够确定导致如此极高能量效率的蛋白质代谢的那些方面。了解极地生物的代谢效率有助于解决长期存在的关于温度补偿和适应极地食物限制的问题。这里的独特方法是强调细胞和亚细胞水平的生物分析，以了解我们拟研究的南极生物的发育、生长、代谢率以及蛋白质合成的速度和成本之间的关系。

0130398ManahanLarval forms are dominant in the life history strategies of invertebrates in marine environments. In Antarctica, energy budget calculations have shown that larval stages of echinoderms have the capacity to survive without food for periods of several months to years. This has led to the speculation that mechanisms of energy metabolism are more efficient in these larval forms, and that this "enhanced efficiency" might be unique to life in extreme cold. Recent studies on the biochemical bases of developmental physiology in Antarctic marine invertebrates have revealed some novel aspects of metabolism in the cold. Contrary to expectations of low metabolism and low rates of macromolecular synthesis in the cold, embryos and larvae of an Antarctic sea urchin have high rates of protein synthesis, while maintaining low rates of metabolism. This apparent paradox was resolved with the recent finding that the cost of protein synthesis in this Antarctic sea urchin is one twenty-fifth of that reported for other animals. This is the highest efficiency for protein synthesis reported for an animal and has important implications for the physiology of growth and development in cold environments. This unique biochemical efficiency of protein synthesis in the cold is the subject of detailed investigation in the current project. The research team will combine expertise in Antarctic larval physiology and biochemistry and molecular biology of sea urchin development to address an experimental plan that is based on three major objectives. (1) The generality of the recent finding of the low cost of protein synthesis in Antarctic sea urchin larvae will be tested by measuring metabolism and protein synthesis during development of other Antarctic echinoderm species. (2) The prediction of a high rate of protein synthesis with low metabolic cost is that growth efficiencies will be high in such organisms. This will be tested by measuring the physiology of protein growth efficiencies in larvae. (3) The unique high efficiency of protein synthesis in Antarctic sea urchin embryos will be studied using specific molecular biology approaches. The combination of these quantitative analyses will enable us to pinpoint those aspects of protein metabolism that result in such extremely high energy-efficiencies. Understanding metabolic efficiency in polar organisms is required to help resolve long-standing questions regarding temperature compensation and adaptations to food limitation in polar regions. The unique approach here is the emphasis on the cellular and sub-cellular levels of biological analysis to understand the relationship among development, growth, metabolic rate, and rates and costs of protein synthesis in the Antarctic organisms we propose to study.