But the apparent genome size restriction might possibly stem from other evolutionary constraints of free-living prokaryotes, such as a cell size limit for efficient intra-cellular diffusion of metabolites and proteins.
It was demonstrated that the presence of two additional rings, pyrazole and pyrimidine, fused to the acridine chromophore structure (PPAC) favoured more rapid cellular diffusion than the presence of only one additional pyrazole ring (PAC).
In particular, omitting the latter can lead to drastic underestimations of cellular diffusion coefficients.
Quantitative measures, such as mean diffusivity (MD) and fractional anisotropy (FA), were proposed to measure the cellular diffusion state and the anisotropy of fibre tract in white matter [ 2] based on DTI.
This means that not only the diffusion of water molecules in the extracellular extravascular space but also cellular diffusion as well as intravascular perfusion contribute to the calculation of the ADC value.
Cellular diffusion is often discussed in connection to effects related to the presence of molecular interactions, like binding or influence of obstacles [20] [23].
Fluctuations due to cellular random movements, resembling cellular diffusion, can originate from active cell migration as well as from processes of cell division and apoptosis [ 547].
Since diffusion of the FSH receptors, much as diffusion of the cytoplasmic estrogen receptors will be restricted by the cell boundaries, even if cellular diffusion was very fast, we will use D R = 10−7 mm s−1, the diffusion coefficient for unhindered membrane diffusion [ 27- 29, 108], for all other receptors.
This model conceptualizes many of the measured intracellular viscosity effects and also accounts for differences in diffusion behaviors in cells (although intracellular viscosity and diffusion are strongly related, we treat cellular diffusion processes separately in the next paragraph).
Thus, these approximations over emphasize the cellular diffusion pathway.
Design of biocompatible scaffolds for bone tissue engineering requires the balance of an osteoinductive cellular microenvironment, diffusion of soluble factors, flexibility, and mechanical loading appropriate for the anatomical site [ 57, 58].
