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

在过去的三十年里，深入的野外研究揭示了南极洲麦克默多海峡韦德尔海豹(Leptonychotes Wedelli)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，高度适应岸上坚固和厚冰栖息地的水生生活。它们必须找到并捕获稀疏分布在冰层下的鱼群。人们对它们潜水行为的了解大多基于对成年动物的研究，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韦德尔海豹骨骼肌中有氧能力、脂肪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起重要作用。这个项目建立在过去结果的基础上，以调查这些适应发展的分子控制。第一个目标是通过酶、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肌肉有氧能力、脂肪代谢和肌红蛋白浓度和分布的个体发育变化。第二个目标是确定在骨骼肌成熟过程中调节这些有氧能力、纤维类型分布和肌红蛋白变化的分子控制。通过消减杂交和随后的分析，将确定不同年龄段的韦德尔海豹游泳肌肉中mRNA群体的差异。这些技术将允许识别影响肌红蛋白浓度、纤维类型分布和有氧能力的个体发育变化的蛋白质和转录因子。这些结果将增加我们对幼年海豹个体发育和分子机制的理解，通过这些机制，幼年海豹获得进行深度(长达700米)和长时间(约20分钟)有氧潜水的生理能力。这项研究将促进对骨骼肌适应的分子调控的了解，使活跃的骨骼肌在低氧条件下发挥作用；这在人类医学中有更广泛的应用，特别是在心脏和肺部疾病方面。其他更广泛的影响包括代表人数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(STAR计划)合作的一个网站的继续，该网站包括每周更新实地考察季节期间的研究工作，每周向学生和教师提问/回答问题，以及全年更新研究结果。

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.