Adhesive contact and protein elastic modulus tune orb weaving spider glue droplet biomechanics to habitat humidity
Adhesive contact and protein elastic modulus tune orb weaving spider glue droplet biomechanics to habitat humidity
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DOI：
10.1016/j.actbio.2022.08.018
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发表时间：
2022-09-29
影响因子：
9.7
通讯作者：
Hendricks, Mary L.
中科院分区：
文献类型：
--
作者：
Opell, Brent D.;Elmore, Hannah Mae;Hendricks, Mary L.
沿着蜘蛛网的粘性捕获线的微小胶滴可以防止昆虫逃跑。每个液滴都是由一个蛋白质核心组成，周围是一层吸湿的水层，这使得液滴的附着力随着湿度的变化而变化。当昆虫挣扎着逃离蛛网时，丝线的粘弹性核心蛋白会延伸，将粘合力传递给丝线的支撑纤维。当吸收的大气水分允许扁平液滴建立足够的粘接接触，同时保持力传递所必需的核心蛋白质凝聚力时，可以实现最大的粘结力。在不同湿度的生境中，研究了不同湿度的12种植物在5种相对湿度下，液滴的粘附力与液滴伸展功之间的关系。考虑液滴扁平面积和核心蛋白弹性模量的回归分析描述了液滴黏附，但以核心蛋白面积代替液滴时，模型下降。来自低湿生境的物种在低湿度条件下表现出更强的粘附性，而来自高湿生境的物种在高湿条件下表现出更强的粘附性。我们的研究结果表明，液滴黏附的一般模型有两个黏附峰，一个是低湿物种的黏附峰，出现在液滴面积增加和蛋白质黏附减少的交叉点上，另一个是高湿物种的黏附峰，出现在液滴面积和蛋白质黏附最大偏离的时候。这种粘附力的双峰现象解释了为什么一些中高湿生境的物种在不同湿度下都表现出较高的粘附力。我们表征了湿度对12种织网蜘蛛胶滴粘附性的影响，并展示了湿度对胶滴外部接触面积、吸湿水层及其蛋白核心刚度的影响。这揭示了液滴粘附是如何被物种栖息地的湿度所调节的，并允许我们修改描述液滴生物力学环境决定因素的模型。(c) 2022作者。由Elsevier Ltd代表Acta Materialia Inc出版。这是一篇基于CC BY-NC-ND许可的开放获取文章（http://creativecommons.org/licenses/by-nc-nd/4.0/）
A B S T R A C T Tiny glue droplets along the viscous capture threads of spider orb webs prevent insects from escap-ing. Each droplet is formed of a protein core surrounded by a hygroscopic aqueous layer, which cause the droplet's adhesion to change with humidity. As an insect struggles to escape the web, a thread's viscoelastic core proteins extend, transferring adhesive forces to the thread's support fibers. Maximum adhesive force is achieved when absorbed atmospheric moisture allows a flattened droplet to establish sufficient adhesive contact while maintaining the core protein cohesion necessary for force transfer. We examined the relationship between these droplet properties and adhesive force and the work of extend-ing droplets at five relative humidities in twelve species that occupy habitats which have different hu-midities. A regression analysis that included both flattened droplet area and core protein elastic modulus described droplet adhesion, but the model was degraded when core protein area was substituted for droplet. Species from low humidity habitats expressed greater adhesion at lower humidities, whereas species from high humidity habitats expressed greater adhesion at high humidities. Our results suggest a general model of droplet adhesion with two adhesion peaks, one for low humidity species, which occurs when increasing droplet area and decreasing protein cohesion intersect, and another for high humidity species, which occurs when area and cohesion have diverged maximally. These dual peaks in adhesive force explain why some species from intermediate and high humidity habitats express high adhesion at several humidities.Statement of significanceWe characterized the effect of humidity on the adhesion of twelve orb weaving spider species' glue droplets and showed how humidity-mediated changes in the contact area of a droplet's outer, hygro-scopic aqueous layer and the stiffness of its protein core affect droplet performance. This revealed how droplet adhesion has been tuned to the humidity of a species' habitat and allowed us to revise a model that describes the environmental determinants of droplet biomechanics.(c) 2022 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )