Gárate Fernanda, Betz Timo, Pertusa María, Bernal Roberto
Departamento de Física and SMAT-C, Universidad de Santiago de Chile, 9170124 Santiago, Chile.
Phys Biol. 2015 Dec 30;12(6):066020. doi: 10.1088/1478-3975/12/6/066020.
In the absence of simple noninvasive measurements, the knowledge of temporal and spatial variations of axons mechanics remains scarce. By extending thermal fluctuation spectroscopy (TFS) to long protrusions, we determine the transverse amplitude thermal fluctuation spectra that allow direct and simultaneous access to three key mechanics parameters: axial tension, bending flexural rigidity and plasma membrane tension. To test our model, we use PC12 cell protrusions-a well-know biophysical model of axons-in order to simplify the biological system under scope. For instance, axial and plasma membrane tension are found in the range of nano Newton and tens of pico Newtons per micron respectively. Furthermore, our results shows that the TFS technique is capable to distinguish quasi-identical protrusions. Another advantage of our approach is the time resolved nature of the measurements. Indeed, in the case of long term experiments on PC12 protrusions, TFS has revealed large temporal, correlated variations of the protrusion mechanics, displaying extraordinary feedback control over the axial tension in order to maintain a constant tension value.
在缺乏简单的非侵入性测量方法的情况下，关于轴突力学的时空变化的知识仍然匮乏。通过将热涨落光谱法（TFS）扩展到长突起，我们确定了横向振幅热涨落光谱，该光谱允许直接并同时获取三个关键力学参数：轴向张力、弯曲挠曲刚度和质膜张力。为了测试我们的模型，我们使用PC12细胞突起——一种著名的轴突生物物理模型——以便简化所研究的生物系统。例如，分别发现轴向张力和质膜张力处于每微米纳牛顿和数十皮牛顿的范围内。此外，我们的结果表明TFS技术能够区分几乎相同的突起。我们方法的另一个优点是测量具有时间分辨特性。实际上，在对PC12突起进行长期实验的情况下，TFS揭示了突起力学的大幅时间相关变化，对轴向张力表现出非凡的反馈控制，以维持恒定的张力值。
