Microswimming as a mechanism for mitochondrial wiggling

Area of Science:

• Cell Biology
• Biophysics
• Biochemistry

Background:

• Plant cells display two mitochondrial motion types: directed and wiggling.
• Directed motion involves cytoskeleton (F-actin, microtubules), but wiggling motion's mechanism is unknown.
• Wiggling suggests non-cytoskeletal motility mechanisms for mitochondria.

Purpose of the Study:

• To investigate the mechanism of non-cytoskeletal mitochondrial wiggling motion.
• To model wiggling mitochondria as active Brownian particles.
• To explore microswimming as a potential driver of mitochondrial wiggling.

Main Methods:

• Modeling wiggling mitochondria as active Brownian particles.
• Applying microswimming theory, specifically a two-sphere swimmer model with peristaltic wave motion.
• Using hydrodynamic results to develop a theoretical probabilistic model incorporating active and passive noise.

Main Results:

• The microswimming model explains mitochondrial wiggling motion at low Reynolds numbers.
• Calculations show that small size deformations can achieve reported mitochondrial speeds.
• The model accounts for the high percentage of wiggling mitochondria interacting with chloroplasts.
• The theoretical model accurately fits experimental data on speed distribution and trajectories.

Conclusions:

• Microswimming, driven by peristaltic shape changes, is a feasible mechanism for mitochondrial wiggling.
• This mechanism explains key observed characteristics of mitochondrial wiggling in plant cells.
• The findings offer new insights into organelle motility beyond cytoskeletal transport.