Intestinal Bicarbonate Secretion, Osmoregulation and Acid-Base Balance in Marine Fish

海鱼肠道碳酸氢盐分泌、渗透调节和酸碱平衡

• 批准号: 0743903
• 负责人: Martin Grosell
• 金额: $ 47.47万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-15 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0743903&HistoricalAwards=false
• 关键词: Intestinal; Bicarbonate; Secretion; Osmoregulation; Acid

The salty marine environment is dehydrating and marine fish are left with seawater as the only source of hydration. In land-dwelling animals ingestion of seawater results in severe diarrhea which, in itself, is dehydrating. In contrast, marine fish are able to absorb fluids from ingested seawater and can successfully eliminate the associated salt gain. The present project aims to further characterize the intestinal processes that allow for these vertebrates to exist in abundance in oceanic environments. Specifically, uptake of chloride across the intestine, which is important for the absorption of water, is the focus of the present research. The PI's previous NSF funded research identified a novel pathway for chloride absorption, which in most fish accounts for at least 50% of the total uptake. This chloride uptake pathway involves the secretion of large quantities of base into the intestinal lumen, but excretion of this base could ultimately result in a challenge to the acid-base balance of the fish. This challenge is met in marine fish by excretion of a proportional amount of acid across their gills to maintain normal blood pH. Through the use of molecular techniques and studies of cells lining the intestinal lumen the goal of this research is to identify the specific proteins involved in this unique chloride uptake pathway. In addition, recently developed equipment, which allows for the determination of both oxygen consumption and ion transport by fish intestine, will be employed to test that hypothesis that absorption of fluid from ingested seawater has a high metabolic cost. Through the course of this research graduate and undergraduate researchers will be trained. In addition, the findings of this research will be incorporated into a university course about the environmental biology of fishes and into an environmental health curriculum targeted to high school teachers in the local public school system, which has a highly diverse demography.

咸水海洋环境正在脱水，海水成为海水鱼类唯一的水合作用来源。陆生动物摄入海水会导致严重腹泻，而腹泻本身就会导致脱水。相比之下，海鱼能够从摄入的海水中吸收液体，并成功消除相关的盐增量。本项目旨在进一步表征这些脊椎动物在海洋环境中大量存在的肠道过程。具体来说，肠道对氯化物的吸收对于水的吸收很重要，是目前研究的重点。 PI 之前由 NSF 资助的研究发现了一种新的氯离子吸收途径，在大多数鱼类中，氯离子吸收量至少占总吸收量的 50%。这种氯化物吸收途径涉及将大量碱分泌到肠腔中，但这种碱的排泄最终可能会对鱼的酸碱平衡造成挑战。海鱼通过鳃分泌一定量的酸来维持正常的血液 pH 值，从而应对这一挑战。通过使用分子技术和对肠腔内壁细胞的研究，本研究的目标是确定参与这种独特的氯离子吸收途径的特定蛋白质。此外，最近开发的设备可以测定鱼肠的耗氧量和离子传输，将用于测试从摄入的海水中吸收液体具有较高代谢成本的假设。通过本研究课程，研究生和本科生研究人员将得到培训。此外，这项研究的结果将被纳入有关鱼类环境生物学的大学课程以及针对人口结构高度多样化的当地公立学校系统高中教师的环境健康课程中。