  Combining extensive single particle tracking microscopy data of endogenous
lipid granules in living fission yeast cells with analytical results we show
evidence for anomalous diffusion and weak ergodicity breaking. Namely we
demonstrate that at short times the granules perform subdiffusion according to
the laws of continuous time random walk theory. The associated violation of
ergodicity leads to a characteristic turnover between two scaling regimes of
the time averaged mean squared displacement. At longer times the granule motion
is consistent with fractional Brownian motion.
