New paper out in Nature Cell Biology!!

In this work we studied how chromosome separation during anaphase scales to the decreasing cell size, characteristic of the cleavage divisions of zebrafish embryos. We observed that the chromosome position at which the nuclear envelope reforms scales with cell size. Zebrafish cells are extremely large and there is no direct contact between the anaphase machinery and the cell cortex, in order to sense cell size and scale. By combining fast spinning disk live imaging with quantitative analysis, we uncovered anaphase cytoplasmic flows that move chromosomes. Flow velocity scales with cell size, scaling chromosome velocity and ultimately scaling the position of nuclear envelope reformation. Flows are generated by friction between viscous cytoplasm and bulky cargo transported by dynein on astral microtubules. We implemented a minimal theoretical model of hydrodynamics of the cytoplasm and concluded that flow velocity scales by the physical confinement of the decreasing cell size. Thus, anaphase cytoplasmic flows span through the entire cell and are a cell geometry sensing mechanism that couples the anaphase segregation machinery to cell size, scaling anaphase.

 See the full story below:

https://www.nature.com/articles/s41556-024-01605-6

 And the “News & Views" from Nicoletta I. Petridou:

https://www.nature.com/articles/s41556-024-01591-9 

The image is a time projection of mitochondria (in the cytoplasm, grey) and chromosomes (center of the cell, orange) during anaphase showing a flow pattern with vortexes. The flow pattern is aligned with the axis of chromosome separation, and therefore, chromosomes move with the flows.