Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans
Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans
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DOI：
10.1073/pnas.1003016107
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发表时间：
2010-11-23
影响因子：
11.1
通讯作者：
Samuel, Aravinthan D. T.
中科院分区：
文献类型：
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作者：
Fang-Yen, Christopher;Wyart, Matthieu;Samuel, Aravinthan D. T.
为了在不同的环境中航行，动物必须能够使其运动步态适应其物理环境。秀丽隐杆线虫（Caenorhabditis elegans）在水中游泳和在表面爬行之间，调整其运动步态以适应施加大约10,000倍机械阻力的环境。在这里，我们通过研究秀丽隐杆线虫在牛顿流体中的波动运动来研究这一壮举，这些流体在粘度上跨越了近五个数量级。在这些流体中，蠕虫的波动步态随外载荷的变化而持续变化：随着载荷的增加，波动的波长和频率都减少。我们还量化了蠕虫身体的内部粘弹性特性及其在运动动力学中的作用。我们将肌肉活动、内部负荷和外部负荷纳入运动的生物力学模型，并表明：(i)肌肉力量在运动步态的变化中几乎是恒定的，（ii）当外部负荷与内部负荷相当时，步态适应就开始了。在由小的外部负荷引起的游泳步态中，肌肉力量主要用于弯曲蠕虫的弹性体。在大外力引起的爬行步态中，利用相当的肌肉力量来驱动外力和弹性体。我们的研究结果表明秀丽隐杆线虫的运动步态不断适应外部机械负荷，以保持推进推力。
To navigate different environments, an animal must be able to adapt its locomotory gait to its physical surroundings. The nematode Caenorhabditis elegans, between swimming in water and crawling on surfaces, adapts its locomotory gait to surroundings that impose approximately 10,000-fold differences in mechanical resistance. Here we investigate this feat by studying the undulatory movements of C. elegans in Newtonian fluids spanning nearly five orders of magnitude in viscosity. In these fluids, the worm undulatory gait varies continuously with changes in external load: As load increases, both wavelength and frequency of undulation decrease. We also quantify the internal viscoelastic properties of the worm's body and their role in locomotory dynamics. We incorporate muscle activity, internal load, and external load into a biomechanical model of locomotion and show that (i) muscle power is nearly constant across changes in locomotory gait, and (ii) the onset of gait adaptation occurs as external load becomes comparable to internal load. During the swimming gait, which is evoked by small external loads, muscle power is primarily devoted to bending the worm's elastic body. During the crawling gait, evoked by large external loads, comparable muscle power is used to drive the external load and the elastic body. Our results suggest that C. elegans locomotory gait continuously adapts to external mechanical load in order to maintain propulsive thrust.