In-vivo study of Yielding and Post-yielding behavior of Cytoplasm and its linkage with the cytoskeleton

We study the yielding and post yielding behavior of cytoplasm in vivo. Cytoplasm, as an omnipresent component of the cells, is known to have finite Young’s modulus and resists deformation, while intracellular cargo transports as fast as micron per second is observed in cytoplasm. In this study, the 3T3 cell line is adapted as a template to investigate the yielding and post yielding behavior of the cytoplasm. We find that cytoplasm yields at 10^2 Pascal scale. The post yielding behavior may be modelled as Bingham fluid. Further control experiment illustrates that both heterogeneity and microtubules significantly contribute to the yielding behavior: The resistance of cytoplasm has multiple resources, and the dynamic assembling and dissembling of the microtubules are essential for yielding. Also, the cytoplasm close to microtubule-organizing centre (MTOC) has higher resistance towards yielding. Our experiment demonstrates the solid to fluid transform of cytoplasm under finite force.