A physical perspective on cytoplasmic streaming (invited)

TL;DR

This paper explores the physics behind cytoplasmic streaming, focusing on how it influences transport and organization in large eukaryotic cells, with insights from the aquatic plant Chara and other organisms.

Contribution

It provides a comprehensive overview of the physical mechanisms and self-organization processes underlying cytoplasmic streaming in large cells.

Findings

Cytoplasmic streaming facilitates efficient transport in large cells.

Self-organization may establish streaming patterns.

Streaming speeds can reach up to 100 μm/s in Chara.

Abstract

Organisms show a remarkable range of sizes, yet the dimensions of a single cell rarely exceed $100$ $\mu$m. While the physical and biological origins of this constraint remain poorly understood, exceptions to this rule give valuable insights. A well-known counterexample is the aquatic plant $Chara$, whose cells can exceed $10$ cm in length and $1$ mm in diameter. Two spiraling bands of molecular motors at the cell periphery drive the cellular fluid up and down at speeds up to $100$ $\mu$m/s, motion that has been hypothesized to mitigate the slowness of metabolite transport on these scales and to aid in homeostasis. This is the most organized instance of a broad class of continuous motions known as "cytoplasmic streaming", found in a wide range of eukaryotic organisms - algae, plants, amoebae, nematodes, and flies - often in unusually large cells. In this overview of the physics of this phenomenon, we examine the interplay between streaming, transport and cell size, and discuss the possible role of self-organization phenomena in establishing the observed patterns of streaming.