Cellular and molecular mechanisms of ion transport by the insect excretory system

昆虫排泄系统离子运输的细胞和分子机制

• 批准号: RGPIN-2021-03575
• 负责人: Ianowski, Juan
• 金额: $ 2.04万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741903
• 关键词: Cellular; molecular; mechanisms; ion; transport

Insects are the most abundant animal group, representing roughly 95% of the known animal species. Although insects appear to be most abundant in the tropics, they have successfully exploited almost every ecological niche of the terrestrial environment including some that lead to major economic, agricultural, or health crisis. In order to deal with the vast number of environmental stresses that these various ecological niches have imposed, insects have evolved sophisticated systems for the control of osmotic and ionic balance that allow most species to regulate their haemolymph composition and volume within a narrow range. The amazing evolutionary adaptations that allow insect to regulate their osmotic state have puzzled researchers for decades. Through my research I will further our understanding of osmoregulation and excretion in insects and the enormous diversity that this group has evolved. In the current grant proposal, we study osmoregulation in the triatomine bloodsucker Rhodnius prolixus, a vector for Chagas disease. Each blood meal loads R. prolixus with excess water and NaCl imposing severe osmotic stress, which the insect resolves with a massive diuretic process. Diuresis is carried out by the excretory system-the Malpighian tubules and crop-which forms urine by active ion transport and osmotically obliged water flow. Diuretic hormones stimulate both the crop and the Malpighian tubules to transport of ions at very high rates. Fully stimulated tubules transport fluid at rates equivalent to each cell exchanging their whole volume every 10 s and their intracellular Na+ and Cl- content in 5 s. This requires highly efficient regulatory mechanisms to ensure ion and fluid homeostasis during postprandial diuresis. In this grant HQP under my supervision at the undergraduate, graduate, and postdoctoral levels will study the hormonal signals that coordinate the function of the crop and Malpighian tubules and the intracellular machinery needed to preserve homeostasis. In addition, my research project will advance our understanding of fundamental mechanisms of epithelial physiology. One of the most interesting questions on epithelial physiology is the nature of the intracellular crosstalk mechanisms which regulate ion transporters to maintain transepithelial transport while defending cytosolic composition. Insect excretory epithelia are ideal models to study these mechanisms, that have remain elusive so far. The knowledge generated through this research will contribute to improve the life of Canadians by facilitating the rational development of cost-effective, insect specific and environmentally benign pest control measures and by providing new knowledge that may help better understand health conditions. Funding from this grant will support the training of HQP on molecular biology, advanced electrophysiology and pharmacology that will prepare them for careers in academia and in industry.

昆虫是数量最丰富的动物类群，约占已知动物物种的 95%。尽管昆虫在热带地区似乎最为丰富，但它们已经成功地利用了陆地环境的几乎所有生态位，包括一些导致重大经济、农业或健康危机的生态位。为了应对这些不同的生态位所施加的大量环境压力，昆虫进化出了复杂的控制渗透和离子平衡的系统，使大多数物种能够在狭窄的范围内调节其血淋巴成分和体积。数十年来，昆虫调节渗透状态的惊人进化适应一直困扰着研究人员。通过我的研究，我将进一步了解昆虫的渗透调节和排泄以及该群体进化的巨大多样性。在当前的资助提案中，我们研究了锥蝽吸血虫Rhodnius prolixus（恰加斯病的媒介）的渗透调节。每次吸血后，R. prolixus 都会摄入过量的水和氯化钠，造成严重的渗透压，昆虫通过大量的利尿过程来解决这一问题。利尿是由排泄系统（马氏小管和嗉囊）进行的，该系统通过活性离子传输和渗透压水流形成尿液。利尿激素刺激嗉囊和马氏小管以非常高的速率运输离子。完全刺激的肾小管输送液体的速率相当于每个细胞每 10 秒交换其全部体积以及 5 秒内交换细胞内 Na+ 和 Cl- 含量。这需要高效的调节机制来确保餐后利尿期间的离子和液体稳态。在这笔拨款中，HQP 在我的监督下，本科生、研究生和博士后水平将研究协调嗉囊和马尔皮基小管功能的激素信号以及维持体内平衡所需的细胞内机制。此外，我的研究项目将增进我们对上皮生理学基本机制的理解。上皮生理学最有趣的问题之一是细胞内串扰机制的性质，该机制调节离子转运蛋白以维持跨上皮转运，同时保护细胞质成分。昆虫排泄上皮是研究这些机制的理想模型，但迄今为止仍难以捉摸。通过这项研究产生的知识将促进合理制定具有成本效益、针对昆虫且对环境无害的害虫防治措施，并提供有助于更好地了解健康状况的新知识，从而有助于改善加拿大人的生活。这笔赠款的资金将支持 HQP 在分子生物学、高级电生理学和药理学方面的培训，为他们在学术界和工业界的职业生涯做好准备。