A New Hypothesis for Cardio-respiratory Mechanics in Insects

昆虫心肺力学的新假说

• 批准号: 1558052
• 负责人: John Socha
• 金额: $ 86.91万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-15 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558052&HistoricalAwards=false
• 关键词: New; Hypothesis; Cardio; respiratory; Mechanics

The immense ecological success of insects makes them extremely important agricultural pests, disease vectors, and food web components. Despite the importance of insects, only a minimal understanding of many aspects of their basic physiology still exists. Blood and air flow are critical for the transport of nutrients, hormones, and gases within an insect's body, but a comprehensive understanding of the biomechanical processes that drive fluid flow is lacking. This project tests a new hypothesis that some insects use an abdominal pump linked functionally to a "gut piston" to generate the principal forces driving air and blood flow. This research is motivated by three questions: 1) How does the abdominal pump help to create airflow and mixing in the insect gas exchange and transport system? 2) How are pressure differences created within the main body cavity? 3) How important is the abdominal pump for circulation? A variety of experimental and computational methods will be used to test for linkages between these systems. This research will clarify how insects pump fluids, and contribute to a broader understanding of mechanically coupled systems, with potential applications in vertebrate (including human) physiology and mechanical engineering. Mechanically-coupled physiological systems have been relatively well-studied in vertebrates, but rarely at the small sizes of insects. This research will provide, therefore, new insights into the physical basis of flow production in the most diverse group of animals on the planet. This project also includes initiatives to involve individuals from diverse backgrounds in research, and to share this research with the local and broader public. This effort includes a new program that will bring Chicago Public School students to Argonne National Laboratory to experience how synchrotron X-rays are used to image insects.This project proposes that the tenebrionid beetle Zophobas morio, and perhaps many insect species, utilizes a linked abdominal pump and "gut piston" to drive the majority of air and blood flow. A new hypothesis posits that 1) the abdominal pump raises hemolymph pressure and displaces a large amount of body volume, inducing airflows and hemolymph flows, and 2) a synchronous "gut piston" pressurizes the thoracic and head compartments, compressing tracheae within them, and thereby further augments pressures that drive air and blood flow within these regions. To test these hypotheses, a combination of newly developed and established techniques to measure abdominal pump volume, cardiac output, hemolymph pressures, hemolymph mixing, and tracheal airflow will be used. Specifically, this project will determine the following: how hemolymph pressures induce compression and airflow in the tracheal system; how differential pressures are created within the coelom and dorsal vessel; and how these components integrate to produce blood flows in the body. To test for linkages between abdominal pumping, hemolymph pressures, gut piston function, hemolymph mixing, and tracheal collapse, correlational approaches will be combined with experimental procedures to directly test the effects of changes in heart and abdominal pump function on airflow and blood circulation. An adaptive and parallelized immersed boundary method will also be used to solve for the flows and mixing patterns generated by the deformations of elastic and/or poroelastic models of the heart, tracheal tubes, and abdomen. Experimental measurements from the beetle will be used to validate the model, and the model will be used to address hypotheses that are difficult to probe experimentally.

昆虫在生态方面的巨大成功使它们成为极其重要的农业害虫、疾病媒介和食物网的组成部分。尽管昆虫很重要，但对其基本生理的许多方面仍然知之甚少。血液和空气的流动对昆虫体内的营养物质、激素和气体的运输至关重要，但对驱动流体流动的生物力学过程的全面理解是缺乏的。这个项目测试了一个新的假设，即一些昆虫使用一个与“肠道活塞”功能相连的腹部泵来产生驱动空气和血液流动的主要力量。本研究的动机是三个问题：1)腹部泵如何帮助在昆虫气体交换和运输系统中产生气流和混合？2)主体腔内的压差是如何产生的？3)腹泵对循环有多重要？将使用各种实验和计算方法来测试这些系统之间的联系。这项研究将阐明昆虫如何泵送流体，并有助于更广泛地理解机械耦合系统，在脊椎动物（包括人类）生理学和机械工程方面具有潜在的应用。机械耦合的生理系统已经在脊椎动物中得到了相对较好的研究，但很少在小尺寸的昆虫中。因此，这项研究将为地球上最多样化的动物群体的流动产生的物理基础提供新的见解。该项目还包括让来自不同背景的个人参与研究的倡议，并与当地和更广泛的公众分享研究成果。这项工作包括一个新项目，将把芝加哥公立学校的学生带到阿贡国家实验室，体验如何使用同步加速器x射线成像昆虫。这个项目提出，拟甲虫（zoophobas morio），也许还有许多昆虫物种，利用一个相连的腹部泵和“肠道活塞”来驱动大部分空气和血液的流动。一种新的假设假设：1)腹部泵提高了血淋巴压力，并置换了大量的身体体积，诱导了空气流动和血淋巴流动；2)一个同步的“肠道活塞”对胸廓和头部腔室加压，压缩其中的气管，从而进一步增加了驱动这些区域内空气和血液流动的压力。为了验证这些假设，将使用新开发和已建立的技术组合来测量腹泵容积、心输出量、血淋巴压、血淋巴混合和气管气流。具体而言，该项目将确定以下内容：血淋巴压力如何诱导气管系统中的压缩和气流；体腔和背血管内的压差是如何产生的；以及这些成分是如何结合在一起产生体内血液流动的。为了测试腹泵、血淋巴压力、肠活塞功能、血淋巴混合和气管塌陷之间的联系，相关方法将与实验程序相结合，直接测试心脏和腹泵功能变化对气流和血液循环的影响。一种自适应的平行浸入边界方法也将被用于求解由心脏、气管和腹部的弹性和/或孔弹性模型的变形所产生的流动和混合模式。甲虫的实验测量将用于验证该模型，该模型将用于解决难以通过实验探测的假设。