The regulation of salt and water balance in aquatic organisms

水生生物盐水平衡的调节

• 批准号: RGPIN-2020-06102
• 负责人: Kelly, Scott
• 金额: $ 3.42万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=717739
• 关键词: regulation; salt; water; balance; aquatic

Life in water can be challenging and a fundamental problem for most animals that reside there is the maintenance of salt and water balance. This is because aquatic animals maintain stable salt levels in the body (e.g. ions such as sodium, chloride, and calcium) despite the fact that many inhabit environments where salt levels are much lower or much higher than body fluids. For example, the salt content of freshwater is considerably lower than that of blood, causing passive ion loss (diffusion) from the body to the surroundings and water loading (excessive hydration). In contrast, for many seawater animals, their surroundings are saltier than their blood, resulting in ion loading and water loss (dehydration). For aquatic animals to maintain salt and water balance, epithelia of ionoregulatory organs function as tissue barriers that regulate the movement of ions and water between fluid compartments (i.e. water and blood). Ion transport across epithelia occurs via two routes. The first is through cells (i.e. the transcellular pathway) and the second is between cells (i.e. the paracellular pathway). Transcellular ion transport is governed by a complex suite of transcellular transport proteins and ion channels that are comparatively well documented in aquatic animals. The paracellular route is governed by proteins of the tight junction (TJ) complex in vertebrates or septate junction (SJ) complex in invertebrates, and in contrast to transcellular transport proteins, very little is known about TJ and SJ proteins in aquatic animals. This is alarming because the permeability of the paracellular pathway in aquatic animals is broadly acknowledged to play an important role in the regulation of salt and water balance. As such we are presented with a serious gap in our fundamental knowledge of how aquatic animals function in a natural setting and how these organisms are equipped to cope with environmental change. My research programs is focused on elucidating the functional properties of TJ and SJ proteins in aquatic animals by identifying new proteins in these animals, characterizing them, studying how they respond to environmental change and examining the functional consequences of knocking down/out TJ or SJ protein gene expression. In the coming cycle I also propose to examine sex-specific differences in the molecular physiology of the aquatic vertebrate TJ complex. This research is important to anyone who has an interest in how aquatic organisms maintain "homeostasis" (i.e. internal stability) or who are interested in how biological material moves across the epithelial barriers of aquatic animals. This is a broad populace that ranges from basic researchers to those who investigate the effects of pollutants and the impact of human activity on aquatic organisms. In addition, those who seek to optimize the delivery of biological material (e.g. drugs) to aquatic organisms via the paracellular pathway are also informed by this research.

水里的生活是具有挑战性的，对于大多数生活在水里的动物来说，一个基本的问题是维持盐和水的平衡。这是因为水生动物体内的盐含量（如钠、氯和钙等离子）保持稳定，尽管许多水生动物生活在盐含量远低于或高于体液的环境中。例如，淡水中的含盐量远低于血液中的含盐量，导致被动离子从体内流失（扩散）到周围环境和水分负荷（过度水合作用）。相比之下，对于许多海水动物来说，它们的环境比血液更咸，导致离子负荷和水分流失（脱水）。水生动物为了维持盐和水的平衡，离子调节器官的上皮作为组织屏障，调节离子和水在流体室（即水和血液）之间的运动。离子在上皮间的转运有两条途径。第一种是通过细胞（即跨细胞途径），第二种是细胞之间（即细胞旁途径）。跨细胞离子转运是由一套复杂的跨细胞转运蛋白和离子通道控制的，这些蛋白和离子通道在水生动物中有比较充分的记载。细胞旁途径是由脊椎动物的紧密连接（TJ）复合物或无脊椎动物的分隔连接（SJ）复合物的蛋白质控制的，与跨细胞运输蛋白相比，水生动物的TJ和SJ蛋白知之甚少。这是令人担忧的，因为水生动物的细胞旁通路的渗透性被广泛认为在盐和水平衡的调节中起着重要作用。因此，我们在水生动物如何在自然环境中发挥作用以及这些生物如何应对环境变化的基本知识方面存在严重差距。我的研究项目集中在阐明水生动物中TJ和SJ蛋白的功能特性，通过鉴定这些动物中的新蛋白，表征它们，研究它们如何响应环境变化，并检查敲除TJ或SJ蛋白基因表达的功能后果。在接下来的周期中，我还建议研究水生脊椎动物TJ复合体分子生理学中的性别特异性差异。这项研究对任何对水生生物如何维持“体内平衡”（即内部稳定性）感兴趣或对生物材料如何跨越水生动物上皮屏障感兴趣的人都很重要。这是一个广泛的人群，从基础研究人员到那些调查污染物影响和人类活动对水生生物影响的人。此外，那些寻求通过细胞旁途径优化生物材料（如药物）递送到水生生物的人也可以从这项研究中获得信息。