Analyzing the spatial positioning of nuclei in polynuclear giant cells

Abstract

How cells establish and maintain a well-defined size is a fundamental question of cell biology. Here we investigated to what extent the microtubule cytoskeleton can set a predefined cell size, independent of an enclosing cell membrane. We used electropulse-induced cell fusion to form giant multinuclear cells of the social amoeba Dictyostelium discoideum. Based on dual-color confocal imaging of cells that expressed fluorescent markers for the cell nucleus and the microtubules, we determined the subcellular distributions of nuclei and centrosomes in the giant cells. Our two- and three-dimensional imaging results showed that the positions of nuclei in giant cells do not fall onto a regular lattice. However, a comparison with model predictions for random positioning showed that the subcellular arrangement of nuclei maintains a low but still detectable degree of ordering. This can be explained by the steric requirements of the microtubule cytoskeleton, as confirmed by the effect of a microtubule degrading drug.

How cortical waves drive fission of motile cells

“…S7), causing the daughter cells to become smaller on average. In addition, the structural integrity of the microtubule cytoskeleton associated with the individual nuclei is known to influence the nuclear distribution in oversized cells (48) and may thus also affect the sizes of daughter cells in the experiment.…”

Slime mold on the rise: the physics of Physarum polycephalum

“…Since the genome of P. polycephalum has been completely sequenced, advances have been made in this area. Stange et al (2017) provide insight into the positioning of nuclei and the microtubule cytoskeleton of Dictyostelium discoideum. Werthmann and Marwan (2017) introduce a Petri-net based approach to the analysis of cellular responses.…”