Time-resolved neurite mechanics by thermal fluctuation assessments

Area of Science:

• Biophysics
• Neuroscience
• Cell Biology

Background:

• Axon mechanics are crucial for neuronal function but difficult to measure noninvasively.
• Existing methods lack the precision to capture temporal and spatial variations in axon mechanics.

Purpose of the Study:

• To develop and validate a noninvasive technique for quantifying key mechanical parameters of axons.
• To investigate the mechanical properties and their regulation in neuronal protrusions.

Main Methods:

• Extension of thermal fluctuation spectroscopy (TFS) to analyze long cellular protrusions.
• Measurement of transverse amplitude thermal fluctuation spectra.
• Application of the technique to PC12 cell protrusions as a model for axons.

Main Results:

• Simultaneous determination of axial tension, bending flexural rigidity, and plasma membrane tension.
• Quantification of axial tension in the nano Newton range and plasma membrane tension in the tens of pico Newtons per micron range.
• Demonstration of TFS's ability to distinguish between similar protrusions and reveal temporal variations in mechanics.

Conclusions:

• TFS provides a powerful noninvasive tool for characterizing axon mechanics.
• PC12 cell protrusions exhibit dynamic mechanical properties with feedback control mechanisms.
• The technique offers insights into the regulation of axial tension in neuronal structures.