Measuring nonequilibrium vesicle dynamics in neurons under tension

Area of Science:

• Neuroscience
• Biophysics
• Cell Biology

Background:

• Vesicle transport is crucial for neuronal function, involving complex active and passive motion.
• Neuronal growth, guidance, and dynamics are influenced by mechanical tension.
• Understanding vesicle transport under mechanical stress is key to neuronal health.

Purpose of the Study:

• To develop and apply a method for analyzing vesicle transport under mechanical strain.
• To characterize the relationship between mechanical tension and active/passive vesicle motion.
• To investigate the sensitivity of neuronal vesicle transport to mechanical stimulation.

Main Methods:

• Utilized temporal Mean Square Displacement (tMSD) analysis.
• Applied mechanical strain (stretching and unstretching) to neurons.
• Quantified parameters like power law scaling, velocity, direction, and flux of vesicle motion.

Main Results:

• tMSD analysis successfully captured transitions between passive and active vesicle motion.
• Vesicle motion in Aplysia neurons was predominantly passive (~8% active).
• Mechanical stretch increased active transport to ~13% with unchanged velocity.
• Unstretching returned active transport to baseline but decreased vesicle velocity.

Conclusions:

• Neuronal vesicle transport is highly sensitive to mechanical stimulation.
• Mechanical tension modulates the active component of vesicle transport.
• The tMSD method provides precise characterization of vesicle dynamics under mechanical strain.