Mixing of finite-size yolk granules in crowded cytoplasm

Determine the mixing and transport properties of finite-size yolk granules in the dense yolk-plasm cytoplasm of a Drosophila oocyte during cytoplasmic streaming, including the effects of yolk-induced changes in cytoplasmic rheology.

Background

The transport simulations use zero-volume tracer particles, an approximation considered reasonable for small mRNA molecules but not for yolk granules, which are several micrometers in size. Consequently, the simulations do not resolve finite-particle effects, particle-particle interactions, or the feedback of a dense yolk suspension on the surrounding fluid.

The authors explicitly identify the mixing properties of cytoplasmic streaming as unresolved and indicate that more sophisticated theoretical and computational models are needed to study dense yolk-plasm rheology and transport.

References

Lastly, there are open questions about the mixing properties of cytoplasmic streaming. Our simulational model, which captured complex fluid-microtubule interactions, considered the enhanced transport properties of zero-volume tracer particles. This is reasonable for small mRNA molecules, but yolk granules are several $\mu\textrm{m}$ in size. We are currently building more sophisticated theoretical and computational models to investigate the effects of a dense yolk plasm on cytoplasmic rheology and transport during streaming.

— Traveling Waves Enhance Transport during Cytoplasmic Streaming in Drosophila Oogenesis  (2609.26656 - Jain et al., 22 Sep 2026) in Discussion