Interplay between metabolism, growth rate, and physical properties of the cytoplasm.

The cytoplasm represents a viscous and crowded environment whose physical properties are highly heterogenous and sensitive to environmental conditions. The state of the cytoplasm is likely to affect the complex network of biochemical reactions and signaling pathways responsible for cellular metabolism and growth, which in turn may regulate cytoplasmic properties. The relationships between the physical properties of the cytoplasm and metabolism, growth rate, and cell cycle progression remain unexplored. Here, we study these relationships in response to nutritional changes in the fission yeast Schizosaccharomyces pombe. In low nitrogen conditions cells exhibited reduced cell elongation rate, increased cell cycle period and increased cytoplasmic diffusion rate, as assayed by nano-rheology using 40 nm GEMs nanoparticles. These findings suggest that in sub-optimal nutrient conditions cells might allocate resources in favor of growth rather than maintaining their intracellular properties.