Conservation rules, their breakdown, and optimality in Caenorhabditis sinusoidal locomotion
Conservation rules, their breakdown, and optimality in Caenorhabditis sinusoidal locomotion
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DOI：
10.1016/j.jtbi.2006.04.012
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发表时间：
2006-10-07
影响因子：
2
通讯作者：
Sternberg, Paul W.
中科院分区：
文献类型：
--
作者：
Karbowski, Jan;Cronin, Christopher J.;Sternberg, Paul W.
波动运动是线虫和无肢脊椎动物的共同特征，但尽管已鉴定出数百个与秀丽隐杆线虫运动有关的基因，但其控制仍不清楚。为了揭示线虫波动运动的机制，我们定量分析了遗传扰动对神经元、肌肉和骨骼（角质层）的影响。我们还比较了不同种类的小杆线虫的运动。我们构建了一个结合力学和生物物理学的理论模型，并受到推进力和肌肉速度以及波动波长和振幅的观察的约束。我们发现，归一化波长是一个保守的数量之间的野生型线虫个体，突变体，并在不同的物种。向前推进的速度与肌肉波的速度成线性比例，相应的斜率也是一个守恒量，几乎是最佳的;例外是在一些突变体影响角质层结构。在理论上，斜率的最优性相当于肌肉和粘弹性体反作用弯矩之间的精确平衡。我们发现，波动的振幅和频率是负相关的，并提供了一个理论解释这一事实。这些实验结果是有效的，无论是年轻的成年人和所有幼虫阶段的野生型线虫。特别是，在发展过程中，振幅与波长呈线性关系，与我们的理论一致。我们还研究了基板硬度对运动参数的影响，发现它不影响上述不变量。在一般情况下，我们的生物力学模型可以解释所观察到的控制线虫波动运动的机制的鲁棒性。(c)2006爱思唯尔有限公司保留所有权利。
Undulatory locomotion is common to nematodes as well as to limbless vertebrates, but its control is not understood in spite of the identification of hundred of genes involved in Caenorhabditis elegans locomotion. To reveal the mechanisms of nematode undulatory locomotion, we quantitatively analysed the movement of C elegans with genetic perturbations to neurons, muscles, and skeleton (cuticle). We also compared locomotion of different Caenorhabditis species. We constructed a theoretical model that combines mechanics and biophysics, and that is constrained by the observations of propulsion and muscular velocities, as well as wavelength and amplitude of undulations. We find that normalized wavelength is a conserved quantity among wild-type C elegans individuals, across mutants, and across different species. The velocity of forward propulsion scales linearly with the velocity of the muscular wave and the corresponding slope is also a conserved quantity and almost optimal; the exceptions are in some mutants affecting cuticle structure. In theoretical terms, the optimality of the slope is equivalent to the exact balance between muscular and visco-elastic body reaction bending moments. We find that the amplitude and frequency of undulations are inversely correlated and provide a theoretical explanation for this fact. These experimental results are valid both for young adults and for all larval stages of wild-type C elegans. In particular, during development, the amplitude scales linearly with the wavelength, consistent with our theory. We also investigated the influence of substrate firmness on motion parameters, and found that it does not affect the above invariants. In general, our biomechanical model can explain the observed robustness of the mechanisms controlling nematode undulatory locomotion. (c) 2006 Elsevier Ltd. All rights reserved.