Quantitative analysis of actin patch movement in yeast

Area of Science:

• Cell Biology
• Biophysics
• Microscopy

Background:

• Cortical actin patches are crucial for yeast cell polarity and morphogenesis.
• Understanding their movement dynamics is key to elucidating cellular processes.

Purpose of the Study:

• To develop and apply a computational method for tracking yeast cortical actin patch motion.
• To investigate the impact of actin depolymerization on patch dynamics.

Main Methods:

• Utilized fluorescence microscopy to capture live yeast cell movies.
• Developed an image-processing algorithm to detect and track 2D patch coordinates.
• Applied a minimum-distance algorithm to connect patch trajectories across frames.
• Analyzed motion using mean-square displacements and a novel criterion for directed motion.

Main Results:

• Yeast cortical actin patch movement, on average, follows a random walk pattern.
• Treatment with latrunculin (an actin-depolymerizing agent) significantly reduced the diffusion coefficient of the patches.
• Latrunculin-treated cells exhibited lower mean-squared patch travel distances compared to control cells.
• Patches were found to move independently, with a notable degree of directed motion observed in control cells, and a lesser extent in treated cells.

Conclusions:

• The developed tracking method effectively quantifies actin patch dynamics.
• Actin polymerization is essential for directed cortical actin patch movement in yeast.
• While primarily random, directed motion plays a significant role in control cell dynamics.