Using calorespirometry to assemble a complete picture of acute hypoxic metabolic depression in fishes

使用热量呼吸测定法来绘制鱼类急性缺氧代谢抑制的完整图像

• 批准号: RGPIN-2021-03109
• 负责人: Regan, Matthew
• 金额: $ 2.77万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742382
• 关键词: Using; calorespirometry; assemble; complete; picture

Human practices are rendering the world's aquatic environments increasingly hypoxic (low O2). This threatens the resident animals because O2 is required to supply sufficient quantities of cellular energy (ATP) to meet the animals' high metabolic demands. However, many animals, especially fishes, are adapted to environments that already experience hypoxia, and we can look to the tolerance strategies of these species to understand what might facilitate or hinder an animal's ability to adapt to a changing world. A highly effective strategy for tolerating hypoxia is metabolic depression (MD), a regulated reduction of metabolic rate - and thus the supply and use of ATP - below resting levels. Not all fishes can induce hypoxic MD, but those that can tend to be highly tolerant of hypoxia. Some of the downregulated cellular ATP-supply and -use processes that contribute to hypoxic MD have been investigated in isolation; however, the upstream signal that induces their downregulation and the manner by which their modulation is linked via time and O2 level (PO2) remain unknown. This Discovery Grant will build significantly upon my previous work to test the overarching hypothesis that diminished hemoglobin (Hb)-mediated O2 supply to the tissues serves as the initial signal for hypoxic MD in fish. Specifically, when water PO2 becomes too low for Hb to bind and deliver sufficient quantities of O2 to the tissues, those tissues induce MD, including the arrest of aerobic and anaerobic ATP-supply pathways and the downregulation of ATP-use processes. Through 4 hypothesis-driven projects, the work will first investigate the role of Hb in hypoxic MD induction through experiments involving calorespirometry and the manipulation of Hb-O2 affinity. Second, it will determine how cellular PO2 affects aerobic ATP supply pathways using high resolution respirometry. Third, it will investigate how the arrest of ATP-supply and -use processes are linked as a function of time and PO2 using cultured tissue cells. And fourth, it will investigate at the cellular level why some species are unable to induce hypoxic MD. The expected outcome of this work is a better understanding of what signals hypoxic MD induction, how its cellular mechanisms are linked sequentially, and what cellular mechanisms differ between species that do and do not use hypoxic MD. Currently, these are unknowns. The proposed work will train 5 graduate (4 MSc, 1 PhD) and 6 undergraduate students, providing them with widely applicable research and analytical skills. Additionally, it will improve our understanding of animal responses to aquatic hypoxia, a phenomenon that is increasing globally (incl. Canada) and threatens innumerable fish populations. Recent work indicates that hypoxic MD may be a rapidly evolved strategy for tolerating hypoxia. Understanding its proximate and ultimate mechanisms may benefit predictive models for identifying potentially vulnerable species and conservation efforts for protecting them.

人类的实践使世界的水生环境越来越低氧（低O2）。这威胁了居民动物，因为需要O2提供足够数量的细胞能量（ATP）以满足动物的高代谢需求。但是，许多动物，尤其是鱼类，适应已经患有缺氧的环境，我们可以研究这些物种的宽容策略，以了解可能有助于或阻碍动物适应不断变化的世界的能力。耐受缺氧的高效策略是代谢抑郁症（MD），代谢率的降低，代谢率的降低，因此ATP的供应和使用低于静息水平。并非所有鱼类都可以诱导低氧MD，但是那些可能高度耐受的鱼类。已经研究了一些导致低氧MD的细胞供应和 - 使用过程。但是，诱导其下调的上游信号以及通过时间和O2水平（PO2）连接其调制的方式的上游信号仍然未知。这项发现赠款将在我以前的工作以检验总体假设的基础上有很大的发展，即对组织的血红蛋白（HB）介导的O2供应减少了FISH中低氧MD的初始信号。具体而言，当水PO2变得太低以至于Hb无法结合并输送足够数量的O2向组织，这些组织会诱导MD，包括停滞有氧和厌氧ATP-supply途径以及ATP使用过程的下调。通过4个假设驱动的项目，该工作将首先通过涉及CalorePimemetry和HB-O2亲和力操纵的实验来研究HB在低氧MD诱导中的作用。其次，它将决定使用高分辨率呼​​吸测定法对有氧ATP供应途径影响有氧ATP供应途径。第三，它将研究如何使用培养的组织细胞将ATP供应和使用过程的停滞作为时间和PO2链接。第四，它将在细胞水平上研究为什么某些物种无法诱导低氧MD。这项工作的预期结果是更好地理解信号的低氧MD诱导，其细胞机制如何顺序连接以及哪些细胞机制在DO和不使用低氧MD的物种之间有所不同。目前，这些是未知数。拟议的工作将培训5名毕业生（4 MSC，1位博士学位）和6名本科生，为他们提供广泛适用的研究和分析技能。此外，它将提高我们对动物对水生缺氧的反应的理解，这种现象在全球增加（包括加拿大）并威胁着无数的鱼类种群。最近的工作表明，低氧MD可能是耐受缺氧的快速发展的策略。了解其近端和最终机制可能会使预测模型有益于识别潜在脆弱的物种和保护它们的保护工作。