The specific importance of K+ in preserving ribosome structure was shown several years ago. Whole ribosomes contain appreciable amounts of K+, which is lost when they dissociate. KCl cannot be replaced by NaCl. Ribosomes from the extreme halophile Ha. Marismortui need molar KCl for stability, and activity. High specificity between K+ and Na+ was also observed in K+ channels, involving specific interactions between K+ ions and water, not seen with Na+. In a 2007 QENS study, published in PNAS, we identified a very slow linear diffusion (suggesting strong confinement) water component in H. marismortui live cells, by using deuterated cell cultures in H2O. We now propose to explore the in vivo role of K+ ions on water dynamics, by experiments on live cells and ribosome fractions under chosen conditions, on IN5 and IN16 to cover the full range of relevant time-scales.