DISSERTATION RESEARCH: Small RNA regulation and the evolution of extreme anoxia tolerance

该项目将追踪脊椎动物低氧耐受性的进化。这项研究可能会揭示支持耐缺氧的新细胞机制，这可能会改变我们对心脏病发作和中风的预防和治疗。如果没有足够的血液流向心脏和大脑，人类和大多数其他脊椎动物只能存活几分钟。血流的丧失阻碍了氧气的供应，并很快导致组织缺氧或缺氧。然而，有少数脊椎动物可以在完全没有氧气的情况下存活几个月。该项目研究并比较了各主要脊椎动物物种耐缺氧相关基因的表达。该项目还将促进国际科学合作，并为一名女性博士生和本科生提供培训。此外，研究成果将被提交给圣玛丽？S学院的科学研究方法课，这是当地一所女子高中。为了研究小RNA的表达和耐缺氧的进化，将研究小RNA的表达在肩鲨、鲫鱼、一年生剑鱼胚胎、豹蛙和淡水龟中的表达。这些物种分别代表最耐缺氧的软骨鱼、硬骨鱼、两栖动物和爬行动物。这项研究测试了常见的小RNA支持这几种最耐受的脊椎动物耐缺氧的假设，表明生活史特征的趋同进化。已知的低氧响应和新的低氧响应小RNA是最近在耐缺氧的一年生金枪鱼中被发现的。该项目将通过比较耐缺氧脊椎动物物种中的小RNA来测试小RNA在耐缺氧进化和维持耐缺氧中的作用。每个物种将暴露在与其生态相关的温度下的缺氧和恢复中，并在3个时间点采样：A.)缺氧前；B.)缺氧时；C.)在缺氧后的有氧恢复过程中。具体的暴露间隔是根据每个物种的最大耐缺氧能力设定的。由于大脑是对缺氧最敏感的器官，因此将从脑组织中提取总RNA，并为小RNA测序做准备，并将比较表达模式。

This project will trace the evolution of low-oxygen tolerance in vertebrates. The study may reveal novel cellular mechanisms underpinning anoxia tolerance, which may transform our prevention and treatment of heart attack and stroke. Humans, and most other vertebrates, can survive for only a few minutes without adequate blood flow to the heart and brain. Loss of blood flow blocks the supply of oxygen, and quickly leads to tissue anoxia, or lack of oxygen. Yet, there are a handful of vertebrates that can survive for months in the complete absence of oxygen. This project examines and compares the expression of genes involved in anoxia tolerance of species from each major vertebrate group. The project will also promote international scientific collaboration and provide training of a female Ph.D. candidate and undergraduate student. Additionally, research findings will be presented to a Science Research Methods class at St. Mary?s Academy, a local all-girls high school.To study small RNA expression and the evolution of anoxia tolerance, small RNA expression will be examined in the epaulette shark, crucian carp, annual killifish embryos, leopard frog, and freshwater turtles. These species represent the most anoxia-tolerant cartilaginous fish, bony fishes, amphibians and reptiles, respectively. This research tests the hypothesis that common small RNAs support the anoxia tolerance of these few most tolerant vertebrates, indicating a convergent evolution of the life history trait. Known hypoxia-responsive and novel anoxia-responsive small RNAs were recently identified in the anoxia tolerant annual killifish Austrofundulus limnaeus. This project will test the role of small RNAs in the evolution and maintenance of anoxia tolerance by comparing them among anoxia-tolerant vertebrate species. Each species will be exposed to anoxia and recovery at its ecologically relevant temperature and sampled at 3 time points: A.) prior to anoxia; B.) during anoxia; C.) during aerobic recovery following anoxia. The specific exposure intervals are set based on the maximal anoxia tolerance of each species. Total RNA will be extracted from brain tissue, since the brain is the most anoxia-sensitive organ, and prepared for small RNA sequencing, and expression patterns will be compared.