| 英文摘要: | 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. |