Respiratory epithelia in vertebrates: sites of chemosensing and neurogenesis

呼吸器官(如肺、鳃和皮肤)对呼吸和氧气摄取的控制对所有脊椎动物的生存都很重要。被称为氧气化学感受器的特殊细胞检测血液或环境中的低氧(称为“缺氧”)，并启动一系列事件，最终导致呼吸频率和心血管功能的生理变化。虽然许多研究已经在哺乳动物中描述了这些细胞，但在鱼类等水生脊椎动物中，氧气化学受体的定义很少。这项发现拨款申请建议进行研究，以填补这些空白，并：(I)确定化学感受器内氧气的“感觉”与其向神经系统传输信号的能力之间的代谢联系；(Ii)确定化学感受器和感觉神经元之间的化学相互作用；以及(Iii)确定鳃再生的基本特性和低氧在化学感受器增殖中的作用。拟议的实验将利用模式脊椎动物斑马鱼的转基因品系，在该品系中，鳃和皮肤的氧气化学感受器可以方便地用绿色荧光标记物标记。我们将在膜离子通道水平上进行灵敏的电生理记录，细胞内钙成像，以及高分辨率共聚焦显微镜。这项研究计划将在五年内平均每年雇用五名研究生和三名本科生。我们的工作将在氧气传感、神经科学、发育和比较生理学领域取得重大进展。我们的研究可能会重新定义所有脊椎动物呼吸控制的工作模式，并将对理解气候变化对水生物种的影响非常重要，因为气候变化深刻地影响着水环境中低氧事件的持续时间和频率。因此，拟议的研究可能会产生重大的环境和经济影响。

The control of breathing and uptake of oxygen by respiratory organs (e.g. lungs, gills and skin) is important to all vertebrates for survival. Specialized cells, called oxygen chemoreceptors, detect low oxygen in the blood or environment (called "hypoxia") and initiate a cascade of events that ultimately leads to physiological changes in respiratory rate and cardiovascular function. While many studies have described these cells in mammals, oxygen chemoreceptors are poorly defined in aquatic vertebrates, such as fish. This Discovery Grant application proposes research to fill these voids and to: (i) Identify a metabolic link between the "sensing" of oxygen within chemoreceptors and their ability to transmit signals to the nervous system; (ii) Determine the chemical interactions between chemoreceptors and sensory neurons; and (iii) Define the basic properties of gill regeneration and the role of hypoxia in chemoreceptor proliferation. The proposed experiments will utilize a transgenic line of the model vertebrate, the zebrafish, in which oxygen chemoreceptors of the gills and skin are conveniently labelled by a green fluorescent marker. We will perform sensitive electrophysiological recording at the level of membrane ion channels, imaging of intracellular calcium, and high-resolution confocal microscopy. This research program will employ an average of five graduate students and three undergraduate students per year over a five-year period. Our work will constitute significant advances in the fields of Oxygen Sensing, Neuroscience, Development and Comparative Physiology. Our studies may redefine working models of respiratory control in all vertebrates, and will be important for understanding the impact of climate change on aquatic species, which profoundly affects the length and frequency of hypoxic events in aquatic environments. The proposed research may therefore lead to major environmental and economic impact.