"Sensing, transfer and regulation of ions and gases: Studies in a model organism, the zebrafish (Danio rerio)"

这项研究建议侧重于对鱼类适应多变环境至关重要的两个关键方面：调节其体液的离子成分以及对呼吸气体O2和CO2的感应和转移。虽然我们已经了解了许多关于离子跨上皮细胞(如鳃和皮肤)移动的机制，但几乎对离子调节的代谢成本知之甚少--跨细胞移动离子的成本(在能量上)是多少？我将使用斑马鱼幼体表皮离子转运细胞的离子吸收作为模型系统来研究这个问题。我和我的学员将使用最先进的扫描极谱和罐装离子选择电极技术来同时测量进入离子细胞的离子和氧气通量，以提供对离子调节的代谢成本的首次直接估计。离子调节领域的其他研究将集中于建立调节机制，允许鱼类在环境挑战期间调整离子吸收速率，例如环境氧气降低(低氧)和盐度变化。 随着气体通道的发现，O2和CO2通过生物膜转移的基本机制正在被重新评估。这项拟议中的研究将利用斑马鱼中“基因敲除”的力量，研究二氧化碳通过水通道(传统上被认为是水通道)和O2通过水通道或Rh蛋白(氨通道)移动的可能性。 氧气和二氧化碳在呼吸表面的转移速度由特殊的化学感受器控制。然而，人们对鱼类接受化学物质的机制知之甚少。这项建议将重点放在碳酸酐酶在二氧化碳化学感受和硫化氢在氧气化学感受中的作用。

This research proposal focuses on two key aspects of fundamental importance to the adaptation of fish to fluctuating environments; regulating the ionic composition of their body fluids and the sensing and transfer of the respiratory gases O2 and CO2. While we have learned much about the mechanisms of ion movement across epithelial such as gills and skin, virtually nothing is know about the metabolic cost of ion regulation - what does it cost (in energy) to move ions across a cell? I will examine this question using ionic uptake by the epidermal ion-transporting cells of zebrafish larvae as a model system. My trainees and I will use state-of-the-art scanning polarographic- and canning ion-selective electrode techniques to simultaneously measure ion and O2 fluxes into ionocytes to provide the first direct estimates of the metabolic cost of ion regulation. Additional research in the field of ion regulation will concentrate on establishing the regulatory mechanisms allowing fish to adjust ion uptake rates during environmental challenges such as lowered ambient O2 (hypoxia) and changing salinity. The basic mechanisms underlying the transfer of O2 and CO2 across biological membranes are being re-evaluated with the discovery of gas channels. The proposed research will exploit the power of "gene knockdown" in zebrafish to examine the possibility that CO2 moves through aquaporins, traditionally thought to function as water channels and that O2 moves though either aquaporins or Rh proteins (ammonia channels). The rate of transfer of O2 and CO2 across respiratory surfaces is governed by their sensing by specialized chemoreceptors. Little is known, however, about the mechanisms of chemoreception in fish. This proposal will focus on the role of carbonic anhydrase in CO2 chemoreception and hydrogen sulphide in O2 chemoreception.