ANT LIA: Hypoxia Tolerance in Notothenioid Fishes

第1部分：非技术描述：全球气候变暖正在增加全球海洋和淡水环境中低氧事件的频率和严重性，这些事件威胁到水生生态系统的健康和鱼类种群的生存能力。南极洲周围的南大洋历史上一直是一个稳定、冰冷和富氧的环境，但现在变暖的速度前所未有，比南半球所有其他地区都要快。南极鱼类在零下的温度中进化，这种温度在很长一段时间内一直保持稳定，其特征使它们能够在寒冷的水域中繁衍生息，但对变暖的适应能力减弱。目前，人们对南极鱼类抵御通常伴随变暖而来的低氧或低氧条件的能力知之甚少。这项研究将调查四种南极鱼类的耐低氧能力，其中包括两种缺乏携氧蛋白--血红蛋白的冰鱼，这可能会损害它们在低氧条件下给组织供氧的能力。四种南极鱼类的耐低氧能力将与居住在南美洲温暖沿海地区的相关鱼类的耐缺氧能力进行比较。将评估和比较五个物种对缺氧的生理和生化反应，以支持我们对南极鱼类应对不断变化的环境的能力的预测。这项研究将为本科生和研究生以及博士后研究员提供培训机会。由太平洋水族馆举办的为期一年的系列研讨会将以在南极洲工作的女科学家为特色，以激励大洛杉矶地区的年轻人追求科学事业。第二部分：技术描述：本项目将检验的总体假设是，与相关的冷温带鱼类相比，南极诺氏鱼类在寒冷、富氧环境中的长期进化降低了它们对缺氧的强大生理、生化和分子反应的能力。研究人员将比较以下几个物种的耐缺氧能力：热血的南极金枪鱼Notothenia coriicep和Notothenia rossii；无血红素的南极冰鱼Chaenocephalus aceratus和Chion odraco rastroSpinosus；基础的寒温性金枪鱼Eleginopsmaclovinus，这是一种从未在极锋以南水域栖息过的物种。维持维持代谢需求所需的最低氧气水平(O2crit)将被量化。然后，动物将暴露在65%的氧气中48小时，通过测量红细胞压积和血红蛋白水平以及大脑、肝脏、糖酵解和心肌中的代谢物来评估对缺氧的反应。有氧和无氧代谢关键酶的最大活性将被量化，以评估在低氧条件下合成ATP的能力。将使用光学和扫描电子显微镜分析鳃的重塑。肝脏和大脑对低氧的分子反应将通过定量氧稳态的主要转录调节因子-1(HIF-1)的水平来表征，低氧基因的表达将使用RNA-Seq来定量。细胞培养将被用来确定先前发现的Nototheniid HIF-1插入突变是否影响HIF-1驱动基因表达的能力，从而影响耐缺氧能力。该项目的结果将提供迄今为止对南极鱼类耐缺氧能力的最全面评估。更广泛的影响包括为本科生和研究生以及博士后研究助理提供研究培训机会，重点是让阿拉斯加原住民学生参与研究。与太平洋水族馆合作，将举办一系列为期一年的公开研讨会，展示9名在南极洲进行研究的妇女的研究和职业生涯。该系列的目标是培养和增强大洛杉矶地区的初中生和高中生追求他们在科学和相关领域的兴趣，并增强研究科学家的公共参与能力，以便他们可以更好地激励STEM领域的青年和早期职业科学家。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1: Non-technical description:Global climate warming is increasing the frequency and severity of low oxygen events in marine and freshwater environments worldwide, and these events threaten the health of aquatic ecosystems and the viability of fish populations. The Southern Ocean surrounding Antarctica has historically been a stable, icy-cold, and oxygen-rich environment, but is now warming at an unprecedented rate and faster than all other regions in the Southern hemisphere. Antarctic fishes have evolved in sub-zero temperatures that have been stable over long periods of time with traits allowing them to thrive in frigid waters, but with diminished resilience to warming temperatures. Presently little is known about the ability of Antarctic fishes to withstand hypoxic, or low-oxygen, conditions that often accompany warming. This research will investigate the hypoxia tolerance of four species of Antarctic fishes, including two species of icefishes that lack the oxygen-carrying protein, hemoglobin, which may compromise their ability to oxygenate tissues under hypoxic conditions. The hypoxia tolerance of four Antarctic fish species will be compared to that of a related fish species inhabiting warmer coastal regions of South America. Physiological and biochemical responses to hypoxia will be evaluated and compared amongst the five species to bolster our predictions of the capacity of Antarctic fishes to cope with a changing environment. This research will provide training opportunities for undergraduate and graduate students, and a postdoctoral research fellow. A year-long seminar series hosted by the Aquarium of the Pacific will feature female scientists who work in Antarctica to inspire youth in the greater Los Angeles area to pursue careers in science.Part 2: Technical description: The overarching hypothesis to be tested in this project is that the long evolution of Antarctic notothenioid fishes in a cold, oxygen-rich environment has reduced their capacity to mount a robust physiological, biochemical, and molecular response to hypoxia compared to related, cold-temperate fish species. Hypoxia tolerance will be compared among the red-blooded Antarctic notothenioids, Notothenia coriiceps and Notothenia rossii; the hemoglobinless Antarctic icefishes, Chaenocephalus aceratus and Chionodraco rastrospinosus; and the basal, cold-temperate notothenioid, Eleginops maclovinus, a species that has never inhabited waters south of the Polar Front. The minimum level of oxygen required to sustain maintenance metabolic requirements (O2crit) will be quantified. Animals will then be exposed to 65% of O2crit for 48 hours, and responses to hypoxia will be evaluated by measuring hematocrit and hemoglobin levels, as well as metabolites in brain, liver, glycolytic and cardiac muscles. Maximal activities of key enzymes of aerobic and anaerobic metabolism will be quantified to assess capacities for synthesizing ATP in hypoxic conditions. Gill remodeling will be analyzed using light and scanning electron microscopy. The molecular response to hypoxia will be characterized in liver and brains by quantifying levels of the master transcriptional regulator of oxygen homeostasis, hypoxia-inducible factor-1 (HIF-1), and hypoxic gene expression will be quantified using RNA-Seq. Cell cultures will be used to determine if a previously identified insertion mutation in notothenioid HIF-1 affects the ability of HIF-1 to drive gene expression and thus, hypoxia tolerance. The results of this project will provide the most comprehensive assessment of the hypoxia tolerance of Antarctic fishes to date. Broader impacts include research training opportunities for undergraduate and graduate students and a postdoctoral research associate, with a focus on involving Native Alaskan students in research. In partnership with the Aquarium of the Pacific, a year-long public seminar series will be held, showcasing the research and careers of 9 women who conduct research in Antarctica. The goal of the series is to cultivate and empower a community of middle and high school students in the greater Los Angeles area to pursue their interests in science and related fields, and to enhance the public engagement capacities of research scientists so that they may better inspire youth and early career scientists in STEM fields.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.