Nitrogen excretion and acid-base regulation in invertebrate systems: Mechanisms, regulation and the specific role of Rh-proteins and AMTs.

无脊椎动物系统中的氮排泄和酸碱调节：Rh 蛋白和 AMT 的机制、调节和具体作用。

• 批准号: 355891-2013
• 负责人: Weihrauch, Dirk
• 金额: $ 2.4万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=549859
• 关键词: Nitrogen; excretion; acid; base; regulation

Ammonia is a highly toxic waste product derived from protein metabolism. In ammoniotelic animals (e.g. aquatic invertebrates and fish), where ammonia is excreted directly and not transformed into less toxic molecules such as urea or uric acid, an effective excretion system is essential to keep cellular and body fluid ammonia levels within a tolerable range. Although ca. 98% (= 30 phyla) of all animals are invertebrates, our knowledge of nitrogen excretion strategies and mechanisms in this dominant group is rather diminutive. The goal of the proposed research is to gain first and detailed insights of ammonia excretion pathways and mechanisms in a wide variety of different invertebrate groups, including annelids (freshwater leeches), nematodes (soil living roundworms), mollusks (freshwater mussels), arachnids (seawater horseshoe crabs) and crustaceans (fresh-, brackish-, and seawater crabs). The proposed research consists of three main objectives, investigating: (1) the actual excretion mechanisms in aquatic invertebrates to explore common ancestral excretion strategies; (2) the evolution and function of the phylogenetic ancient bacterial and plant "AMTs" and the distantly related animal "Rh-proteins" in the soil nematode Caenorhabditis elegans, a transitional animal that expresses both types of ammonia transporters; (3) the relation of ammonia excretion and acid-base balance in crustaceans and the effects of predicted increases in global aquatic pCO2 levels and ocean acidification on the pH-regulation in euryhaline crabs. The three objectives will provide novel insights of the evolution of ammonia excretion mechanisms and acid-base regulation in phylogentic ancient invertebrates, including the roles of Rh-proteins and AMTs as NH3, CO2 or H+ -channels. It is expected that fundamental and general nitrogen excretion and pH regulatory strategies will be discovered. Understanding the ammonia excretion mechanisms as well as the animal's responses towards elevated environmental ammonia levels are crucial for conservation programs, which are intended to protect animal communities living in aquatic habitats threatened by ammonia-rich agricultural run-off and also to manage aquaculture facilities.

氨是一种来自蛋白质代谢的剧毒废物。在氨动物（例如水生无脊椎动物和鱼类）中，氨直接排泄，不会转化为毒性较小的分子，如尿素或尿酸，有效的排泄系统对于将细胞和体液氨水平保持在可耐受的范围内至关重要。虽然大约。所有动物中 98%（= 30 门）都是无脊椎动物，我们对这一优势群体的氮排泄策略和机制的了解相当少。拟议研究的目标是首先详细了解各种不同无脊椎动物群体的氨排泄途径和机制，包括环节动物（淡水水蛭）、线虫（土壤活蛔虫）、软体动物（淡水贻贝）、蜘蛛动物（海水鲎）和甲壳类动物（鲜蟹、咸蟹和海水蟹）。拟议的研究包括三个主要目标，调查：（1）水生无脊椎动物的实际排泄机制，探索共同的祖先排泄策略； （2）土壤线虫秀丽隐杆线虫（一种表达两种类型氨转运蛋白的过渡动物）中系统发育古老细菌和植物“AMT”以及远缘动物“Rh-蛋白”的进化和功能； (3) 甲壳类动物的氨排泄和酸碱平衡的关系，以及全球水生二氧化碳浓度的预测增加和海洋酸化对广盐蟹 pH 调节的影响。这三个目标将为系统发育古代无脊椎动物的氨排泄机制和酸碱调节的进化提供新的见解，包括 Rh 蛋白和 AMT 作为 NH3、CO2 或 H+ 通道的作用。预计将发现基本和通用的氮排泄和 pH 调节策略。了解氨排泄机制以及动物对环境氨水平升高的反应对于保护计划至关重要，保护计划旨在保护生活在受富含氨农业径流威胁的水生栖息地的动物群落，并管理水产养殖设施。