CRUI: Osmoregulation in Euryhaline Fish: Physiology, Ecology and Molecular Biology.

CRUI：广盐鱼类的渗透调节：生理学、生态学和分子生物学。

• 批准号: 0111860
• 负责人: Robert Preston
• 金额: --
• 依托单位: Board of Trustees of Illinois State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0111860&HistoricalAwards=false
• 关键词: CRUI; Osmoregulation; Euryhaline; Fish; Physiology

Most fish are confined entirely to fresh water (FW) or seawater (SW) and cannot live in or adapt to the other environment. What may be surprising is that the internal salts and organic molecules (solutes) in the blood of all bony fishes are maintained in an "intermediate" concentration (which is actually similar to that in mammals). In other words, fish in salt water may suffer stress because they are living in a medium about 3 times as salty as their blood and therefore must "pump out" extra salt that is ingested. This requires molecular transport proteins (such as the sodium/potassium pump and other ion pumps and channels). FW fish, on the other hand, face the problem of becoming "waterlogged". In other words, the higher concentrations of salts in their tissues and blood cause the fish to gain water by diffusion (also called osmosis). These fish must rid themselves of the extra water and conserve salts. They do this by using molecular transport proteins. In general the control of internal salt and water balance (osmoregulation) requires significant metabolic energy to power it. As most people know, a small number of fish like salmon and eels spend a part of their life in FW and part of their life in SW. These fish literally switchover from the FW metabolism to the SW metabolism, a process that may be metabolically stressful. A surprising little fish (3 inches long), the killifish (Fundulus heteroclitus), has been shown to have phenomenal osmoregulatory abilities. This fish can survive indefinitely in FW or in SW up to 3 times more concentrated than ocean water. Furthermore, killifish may migrate daily from SW to FW and back to feed (and to breed and lay eggs in the Spring) making them appear to be unusually adept at osmoregulation. At present there is intense interest in the metabolic machinery and especially the molecular transport proteins that are involved. Indeed, many of the same types of proteins and their responses to salinity change that are found in killifish also are found in salmon and eels. However, with killifish (and perhaps other fish as well) another mechanism, to deal with salinity stress has been suggested, termed behavioral osmoregulation. The heart of this hypothesis is that, all other things being equal, killifish will try to swim up FW streams to the point where their internal salt and water composition resembles that of the external water (about 1/3 strength SW) and stay there conserving metabolic energy that would otherwise be expended pumping salts in or out of the fish. Preliminary data support the hypothesis that killifish may seek salinities about 1/3 that of SW. This new idea has broad implications physiologically and ecologically. The principal investigators will measure the metabolic energy requirements for osmoregulation in killifish. Using DNA based techniques, they will measure the presence of and changes in the molecular transport proteins in killifish. They also will investigate the ecology of wild killifish and attempt to correlate natural distributions and breeding behavior with projected salinity preferences. A very important part of this project is that the principal investigators will lead a team of 8 undergraduate students per year (for each of 4 years) who will work during their academic year on this research at their home institutions and then come to Mount Desert Island Biological Laboratory for 2 months during the summer to do fieldwork, physiology and molecular biology. The students will have the opportunity to do original research while learning modern techniques in many fields at one of the country's finest marine laboratories. It is expected that this experience show these students the passion and fulfillment of scientific research that will motivate them in their future careers.

大多数鱼完全被限制在淡水(FW)或海水(SW)中，不能在其他环境中生活或适应。可能令人惊讶的是，所有硬骨鱼血液中的内源性盐分和有机分子(溶质)都保持在一个中等浓度(这实际上与哺乳动物的浓度相似)。换句话说，咸水中的鱼可能会承受压力，因为它们生活在大约是血液含盐量3倍的介质中，因此必须将摄入的额外盐分“抽出来”。这需要分子运输蛋白(如钠/钾泵和其他离子泵和通道)。另一方面，FW鱼面临着变得“浸水”的问题。换句话说，鱼的组织和血液中的盐分浓度较高，导致鱼通过扩散(也称为渗透)获得水分。这些鱼必须排出多余的水分并保存盐分。他们通过使用分子运输蛋白来做到这一点。一般来说，体内盐分和水分平衡的控制(渗透调节)需要大量的新陈代谢能量来提供动力。正如大多数人所知道的，像鲑鱼和鳗鱼这样的一小部分鱼，它们的一部分生活在FW，一部分它们的生活在西南。从字面上讲，这些鱼从FW新陈代谢切换到SW新陈代谢，这一过程可能会产生代谢压力。一种令人惊讶的小鱼(3英寸长)--千里鱼(Fundulus Heterocltes)--被证明具有惊人的渗透调节能力。这种鱼可以无限期地在FW或比海水浓度高3倍的西南地区生存。此外，剑鱼可能每天从西南部迁徙到FW，然后回来觅食(并在春季繁殖和产卵)，这使得它们看起来非常擅长渗透调节。目前，人们对代谢机制，特别是其中涉及的分子运输蛋白有着浓厚的兴趣。事实上，在鲑鱼和鳗鱼中也发现了许多相同类型的蛋白质及其对盐度变化的反应。然而，对于剑鱼(也许还有其他鱼类)，已经提出了另一种应对盐分压力的机制，称为行为渗透调节。这一假设的核心是，在所有其他条件相同的情况下，千里鱼将试图沿着FW溪流向上游，直到它们内部的盐分和水的组成与外部水的组成相似(大约1/3强度西南)，并停留在那里，以保存代谢能量，否则这些能量将被消耗在将盐分泵入或抽出鱼的过程中。初步数据支持这样一种假设，即小剑鱼可能寻求的盐度约为西南的1/3。这一新想法在生理学和生态学上都有广泛的影响。主要研究人员将测量七条鱼渗透调节所需的代谢能量。使用基于DNA的技术，他们将测量千里鱼中分子运输蛋白的存在和变化。他们还将调查野生剑鱼的生态，并试图将自然分布和繁殖行为与预测的盐度偏好联系起来。该项目的一个非常重要的部分是，首席研究人员将带领一个由8名本科生组成的团队(每4年一次)，他们将在学年期间在自己的机构从事这项研究，然后在夏季来到荒山岛生物实验室进行为期2个月的实地考察、生理学和分子生物学。学生们将有机会在该国最好的海洋实验室之一进行原创研究的同时，在许多领域学习现代技术。预计这一经历将向这些学生展示他们对科学研究的热情和成就感，这将激励他们未来的职业生涯。