Sol-gel Transition Drives Hyper-fast Mixing in a Giant Cell

Area of Science:

• Cell Biology
• Biophysics
• Microscopy

Background:

• Cytoplasm is a crowded fluid where cellular components mix.
• High viscosity and laminar flow in amoebas typically hinder efficient mixing.
• Previous understanding suggested gel transitions occurred only at cell edges.

Purpose of the Study:

• Investigate mixing mechanisms in the giant amoeba *Chaos carolinensis*.
• Test if cellular deformations cause chaotic mixing.
• Identify the strategy amoebas use for rapid cytoplasmic mixing.

Main Methods:

• Live cell tracking of injected beads.
• Computational analysis of motion and mixing.
• Studied *Chaos carolinensis*.

Main Results:

• Amoebas accelerate mixing via a novel cytoplasmic gel state capture and release strategy.
• Gel transitions occur throughout the mid-cell region, not just at the edges.
• Nearly complete mixing is achieved within 1-2 cytoplasmic flow cycles.

Conclusions:

• *Chaos carolinensis* employs a unique gel state mechanism for rapid cytoplasmic mixing.
• This strategy approximates the Bernoulli mixing regime, indicating highly efficient mixing.
• The findings reveal a previously unknown mechanism for rapid intracellular transport and mixing.