Intracellular Diffusion in Fission Yeast Cells Depends on Cell Cycle Stage

Abstract

During the cell cycle, rearrangements of the cytoskeletal network play an essential role, in particular for the success of cell division. In order to quantify the influence of cytoskeletal rearrangements on the viscoelastic properties of the intracellular space, we studied the diffusion of endogenous lipid granules within single fission yeast cells in the different stages of the cell cycle. The position of the granules was tracked with optical tweezers at nanometer and sub-millisecond resolution and the data were analyzed with a power spectral analysis. We found that the majority of the lipid granules underwent subdiffusive motion during all stages of the cell cycle, i.e. the mean squared displacement of the granule is 2Dtα with α<1. With our experiments we have shown that α is significantly smaller during interphase than during any stage of mitotic cell division and, surprisingly, we did not find significant differences of α in the different stages of cell division. These results indicate that the cytoplasm is more elastic during interphase than during cell division and that its elasticity is relatively constant during the stages of cell division.