The Molecular Signals that Regulate the Ontogeny of Aerobic Capacity, Lipid Metabolism and Elevated Myoglobin Concentrations in the Skeletal Muscles of Weddell Seals

在过去的三十年中，深入的实地研究揭示了南极麦克默多湾威德尔海豹（Leptonychotes weddelli）种群的行为、生理、生活史和种群动态。这些动物是海洋捕食者，高度适应滨快和浮冰栖息地的水生生物。他们必须找到并捕捉冰下稀疏分布的冰川。大多数关于它们潜水行为的了解都是基于对成年动物的研究，而对幼年动物潜水行为的发育或遗传控制知之甚少。该项目的目标是研究幼年威德尔海豹骨骼肌中有氧能力、脂质代谢和氧气储存的时间发展，并确定细胞环境的哪些方面在成熟过程中对这些适应的调节是重要的。该项目以过去的研究结果为基础，研究这些适应性发展背后的分子控制。第一个目标是利用酶、免疫组织化学和肌红蛋白分析进一步表征新断奶海豹、亚成年海豹和成年海豹的肌肉有氧能力、脂质代谢和肌红蛋白浓度和分布的个体发生变化。第二个目标是确定在成熟过程中调节骨骼肌有氧能力、纤维类型分布和肌红蛋白变化的分子控制。通过减法杂交和后续分析，确定威德尔海豹不同年龄组游泳肌mRNA种群的差异。这些技术将允许鉴定影响肌红蛋白浓度、纤维类型分布和有氧能力的个体发生变化的蛋白质和转录因子。这些结果将增加我们对幼海豹获得深水（高达700米）和长时间有氧潜水（约20分钟）生理能力的个体发生和分子机制的理解。这项研究将推进分子调控的知识，使活跃的骨骼肌在缺氧条件下发挥作用；这在人类医学上有更广泛的应用，特别是在心肺疾病方面。其他更广泛的影响包括代表性不足的科学家的参与，以及与西南大学科学教师获取资源计划（STARS Program）合作的网站的继续，该网站在实地季节每周更新研究工作，每周有学生和教师参加的问答会议，以及全年更新研究成果。

During the past three decades, intensive field studies have revealed much about thebehavior, physiology, life history, and population dynamics of the Weddell seal (Leptonychotes weddelli) population of McMurdo Sound, Antarctica. These animals are marine predators that are highly adapted for an aquatic life in shore-fast and pack ice habitats. They must locate and capture sparsely distributed under the ice. Most of what is known about their diving behavior is based on studies of adult animals with little known about the development or the genetic controls of diving behavior of young animals. The goal of this project is to examine the temporal development of aerobic capacity, lipid metabolism and oxygen stores in the skeletal muscles of young Weddell seals and to determine which aspects of the cellular environment are important in the regulation of these adaptations during maturation. This project builds on past results to investigate the molecular controls that underlie the development of these adaptations. The first objective is to further characterize the ontogenetic changes in muscle aerobic capacity, lipid metabolism and myoglobin concentration and distribution using enzymatic, immuno-histochemical and myoglobin assays in newly weaned, subadult, and adult seals. The second objective is to determine the molecular controls that regulate these changes in aerobic capacity, fiber type distribution and myoglobin in skeletal muscles during maturation. Through subtractive hybridization and subsequent analysis, differences in mRNA populations in the swimming muscles of the different age classes of Weddell seals will be determined. These techniques will allow for the identification of the proteins and transcription factors that influence the ontogenetic changes in myoglobin concentration, fiber type distribution and aerobic capacity. These results will increase ourunderstanding of both the ontogeny and molecular mechanisms by which young seals acquire the physiological capabilities to make deep (up to 700 m) and long aerobic dives (ca 20 min). This study will advance knowledge of the molecular regulation for theadaptations that enable active skeletal muscle to function under hypoxic conditions; this has a broader application for human medicine especially in regards to cardiac and pulmonary disease. Additional broader impacts include the participation of underrepresented scientists and a continuation of a website in collaborationwith the Science Teachers Access to Resources at Southwestern University (STARS Program) which involves weekly updates about research efforts during the field season, weekly questions/answer session involving students and teachers, and updates on research results throughout the year.