Analysis of nematode mechanics by piezoresistive displacement clamp
Analysis of nematode mechanics by piezoresistive displacement clamp
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DOI：
10.1073/pnas.0702138104
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发表时间：
2007-10-30
影响因子：
11.1
通讯作者：
Pruitt, Beth L.
中科院分区：
文献类型：
--
作者：
Park, Sung-Jin;Goodman, Miriam B.;Pruitt, Beth L.
研究动物力学对于了解神经肌肉系统中的信号如何产生行为，以及力敏感器官和感觉神经元如何工作至关重要。很少有技术可以提供适合于这类研究的力和位移。为了解决这一技术差距，我们开发了一种计量学，使用压阻式悬臂梁作为力-位移传感器，连接到反馈系统，以向微米级的动物施加和维护定义的载荷分布。结果表明，该系统可以在距离100克的范围内传输10(-8)到10(-3)N的力，分辨率为12 nN(0.1赫兹到100千赫兹)。我们使用这种新的测量方法显示，野生型线虫(线虫)的力-位移曲线是线性的。由于线虫具有近似的圆柱体，这一发现表明，线虫的体力学可以建模为受压的圆柱壳。然而，人们对静水压力和壳体力学的相对重要性知之甚少。我们发现，通过角质层穿刺法消除压力或通过高渗休克降低压力对硬挺度的影响不大，而改变身体形状和角质层蛋白质的dpy-5和lon-2基因缺陷分别使硬挺度降低和增加25%和50%。这项对Celegans身体力学的初步分析表明，贝壳力学决定了僵硬程度，这是理解身体力学如何影响运动和力感觉的第一步。
Studying animal mechanics is critical for understanding how signals in the neuromuscular system give rise to behavior and how force-sensing organs and sensory neurons work. Few techniques exist to provide forces and displacements appropriate for such studies. To address this technological gap, we developed a metrology using piezoresistive cantilevers as force-displacement sensors coupled to a feedback system to apply and maintain defined load profiles to micrometer-scale animals. We show that this system can deliver forces between 10(-8) and 10(-3) N across distances of up to 100 gm with a resolution of 12 nN between 0.1 Hz and 100 kHz. We use this new metrology to show that force-displacement curves of wild-type nematodes (Caenorhabditis elegans) are linear. Because nematodes have approximately cylindrical bodies, this finding demonstrates that nematode body mechanics can be modeled as a cylindrical shell under pressure. Little is known about the relative importance of hydrostatic pressure and shell mechanics, however. We show that dissipating pressure by cuticle puncture or decreasing it by hyperosmotic shock has only a modest effect on stiffness, whereas defects in the dpy-5 and lon-2 genes, which alter body shape and cuticle proteins, decrease and increase stiffness by 25% and 50%, respectively. This initial analysis of C elegans body mechanics suggests that shell mechanics dominates stiffness and is a first step in understanding how body mechanics affect locomotion and force sensing.