Basic theory of anomalous subdiffusive motion (transport without significant hydrodynamic flow)

Anomalous subdiffusive measurements by fluorescence correlations spectroscopy and simulations of translational diffusive behavior in live cells.

Trapping of molecules in live cells can exert at least two types of effects that could be important for function. First, live cells will have a strong influence on how far and how fast locally produced molecules will travel within the cytoplasm or the nucleoplasm. Over a time scale of 1 s, a molecule with an apparent diffusion coefficient Dapp of 2 μm2/ms, would diffuse about 60 μm. Thus, as long as molecules remained within the cytoplasm, their movement could be dominated by an anomalous diffusion process over distances. Second, anomalous diffusion reflects an increase in the spatial and temporal correlation of diffusing molecules which would be expected to promote activation of biochemical networks by intracellular signals trapped in live cells.