Micro-mechanics and Structure-function relationships in spider mechano-sensors; a key to understanding organ- performance

生物体的一个基本属性是它们能够监测不同的环境信号并优先对它们作出反应。在生物体中发现的丰富的自然感觉系统可以作为系统感觉系统和材料开发的灵感和指南；为此，需要在传感器-材料水平上对感觉机制有深入的了解。节肢动物的机械传感器包括声音、触觉、介质流动和表面振动传感器，这些传感器特别令人感兴趣，可以解释复杂的空间和时间环境信号，而无需中枢神经系统进行少量处理。蜘蛛机械传感器表现出非凡的灵敏度，通常在极低的刺激阈值水平下工作。单个机械传感器对特定范围的刺激频率具有高度选择性，并能有效地过滤与生物无关的扰动。机械传感器阵列充当复合感觉器官，提供高度的空间和方向分辨率。到目前为止，大部分的工作都是关于感觉器官的宏观和微观机械感觉功能，而对其材料水平的结构和机械特性的关注非常有限。本研究的主要假设是，基本生物复合结构（即几丁质纤维和蛋白质）的特定空间排列，构成感觉器官的材料的成分梯度，以及它们周围的角质层，在它们的机械感觉功能中起着至关重要的作用。我们认为，蜘蛛机械传感器的灵敏度和特异性不仅源于它们的局部形态和它们作为一个复合器官的空间排列，而且源于它们潜在的微纳米结构排列。因此，为了阐明天然机械感受器的基本原理，我们建议对蜘蛛的机械感觉系统、狭缝器官和感觉毛进行研究，在材料水平上对它们的层次结构组织、成分梯度和微纳米力学性能进行表征，并将它们整合到从材料水平到器官水平的多尺度物理模型中。这将使我们能够确定检测、传输和过滤机械刺激的物质层面机制。

A fundamental attribute of living organisms is their ability to monitor different environmental signals and preferentially react to them. The abundance of natural sensory systems found in living organisms may serve as an inspiration and as a guide for the development of systemic sensory systems and materials; for this, an in depth understanding of the sensory mechanisms at the sensor-material level is required. The mechano-sensors of arthropods include sound, touch, medium flow and surface vibrations sensors of particular interest - allowing the interpretation of complex spatial and temporal environmental signals with little processing by the central nervous system. Spider mechanosensors exhibit remarkable sensitivity and typically operate at an extremely low stimuli threshold level. Individual mechanosensors are highly selective for a particular range of stimulus frequencies along with effective filtering of biologically non-relevant perturbation. Arrays of mechano-sensors act as compound-sensory organs and provide a high degree of spatial and directional resolution. Most of the work so far has dealt with the macro- and microscopic mechno-sensory functionalities of the sensory organs, while very limited attention has been given to their material-level structural and mechanical characteristics. The main hypothesis of this study is that the specific spatial arrangement of the basic biocomposite architecture (i.e. chitin fibers and proteins), the compositional gradients in the material forming the sensory organs, and importantly, the cuticle around them, play crucial roles in their mechano-sensory functionalities. We suggest that the sensitivity and specificity of the spider mechano-sensors stem not only from their local morphology and their spatial arrangement as a compound organ, but also from their underlying micro- and nanostructural arrangement. Thus, in order to elucidate the fundamental principles found in natural mechanoreceptors we propose here to investigate spider mechano-sensory systems, the slit organ and sensory hairs, characterize them on the material-level in terms of their hierarchical structural organization, compositional gradients and micro- and nano-mechanical properties, and integrating them into multi-scale physical models, from the material-level up to the organ level. This will allow us to identify the material-level mechanisms for the detection, transmission and filtration of the mechanical stimuli.