Biomechanics and biophysics of anti-predator defence in hagfishes

盲鳗抗捕食者防御的生物力学和生物物理学

• 批准号: RGPIN-2016-04967
• 负责人: Fudge, Douglas
• 金额: $ 4.08万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615411
• 关键词: Biomechanics; biophysics; anti; predator; defence

Hagfishes are an ancient group of eel-like, benthic, marine animals that are believed to have appeared over half a billion years ago. One possible explanation for the evolutionary staying power of hagfishes has to do with their ability to defend themselves from predators by secreting large volumes of fibrous slime in a fraction of a second. Over the course of my last two Discovery grants, my lab has elucidated several mechanisms underlying the function of the slime. We have shown that, in addition to seawater, the slime consists of two main components, mucus and threads, which are present in very low concentrations. We have also shown that the deployment of exudate from the slime glands involves the unraveling of coiled slime threads, the swelling of mucus vesicles, and a complex interplay among these two components. We have shown that the deployment of the fibrous component of the slime involves the dissolution of a seawater soluble glue and the release of strain energy stored in the coiled thread. We recently elucidated the three dimensional structure of slime threads within the specialized cells that produce them, which has inspired us to investigate the biophysical mechanisms by which the thread is produced within these cells. We have found that there are two main kinds of mucous vesicles, and they differ in their requirement for calcium ions to rupture. We have also shown that aquaporins in the vesicle membrane accelerate their swelling in seawater. The research proposed here will attempt to answer the following questions about how hagfish slime functions and how it is produced in the slime glands: How do gland thread cells produce an exquisitely coiled and remarkably strong slime thread in their cytoplasm that is 150,000 times longer than it is wide? What drives the swelling of the mucus vesicles in seawater and what keeps them condensed within the slime gland? We have shown that hagfish slime is remarkably good at clogging the gills of fish predators, and until recently, we assumed that the slime was effective at preventing attacks from predators. However, recently published deep-sea videos of hagfishes show that the slime is released only after it is bitten by a predator. This observation leads to the intriguing question of how a hagfish survives the initial bite, especially when that bite comes from a formidable predator like a shark. To answer this question, we will test biomechanical hypotheses about how hagfishes avoid injury from these initial bites. Overall, the research proposed here will illuminate the mechanisms by which hagfishes defend themselves from predators, and may lead to novel biomimetic technologies in the areas of puncture resistance and the manufacture of high performance materials. It may also help us understand how these unique animals have survived on this planet for so long.

盲鳗是一种古老的鳗鱼类底栖海洋动物，据信出现在5亿多年前。盲鳗进化持久力的一个可能的解释是，它们能够在几分之一秒内分泌大量的纤维状粘液，以保护自己免受捕食者的攻击。在我最近的两次发现赠款过程中，我的实验室已经阐明了粘液功能的几种机制。我们已经表明，除了海水，粘液由两种主要成分组成，粘液和线程，这是在非常低的浓度。我们还表明，粘液腺分泌物的部署涉及解开卷曲的粘液线，粘液囊泡的肿胀，以及这两个组成部分之间的复杂相互作用。我们已经表明，部署的纤维成分的粘液涉及溶解的海水可溶性胶和释放的应变能存储在螺旋线。我们最近阐明了产生粘液丝的专门细胞内粘液丝的三维结构，这启发了我们研究这些细胞内产生粘液丝的生物物理机制。我们发现，有两种主要的粘液囊泡，它们对钙离子破裂的要求不同。我们还表明，囊泡膜中的水通道蛋白加速其在海水中的溶胀。这里提出的研究将试图回答以下问题，即盲鳗粘液是如何发挥作用的，以及它是如何在粘液腺中产生的：腺丝细胞是如何在细胞质中产生一条精致卷曲且非常坚固的粘液丝的，它的长度是宽度的150，000倍？是什么驱使海水中的粘液囊泡膨胀，又是什么使它们在粘液腺中凝结？我们已经证明，盲鳗粘液非常善于堵塞鱼类捕食者的鳃，直到最近，我们还认为粘液可以有效地防止捕食者的攻击。然而，最近公布的八目鳗的深海视频显示，粘液只有在被捕食者咬伤后才会释放出来。这一观察结果引出了一个有趣的问题：盲鳗如何在最初的咬伤中幸存下来，特别是当咬伤来自像鲨鱼这样可怕的捕食者时。为了回答这个问题，我们将测试关于盲鳗如何避免这些最初的叮咬伤害的生物力学假设。总的来说，这里提出的研究将阐明盲鳗保护自己免受捕食者的机制，并可能导致新的仿生技术领域的耐穿刺性和高性能材料的制造。它也可能帮助我们了解这些独特的动物是如何在这个星球上生存这么久的。