Unravelling the dissolution mechanism of polyphosphate glasses by P NMR spectroscopy: ligand competition and reactivity of intermediate complexes.

Phosphate glass dissolution can be tailored via compositional and subsequent structural changes, which is of interest for biomedical applications such as therapeutic ion delivery. Here, solid-state P nuclear magnetic resonance characterisation of 45PO-xCaO - (55 -x)NaO glasses was correlated with dissolution studies using time-dependent liquid P NMR spectroscopy and quantitative chemical analysis. Glasses dissolved congruently in aqueous media, and the first dissolution stage was the hydration of phosphate chains.

Phosphatase-dependent fluctuations in DNA-damage checkpoint activation at partially defective telomeres.

Telomeres protect the ends of eukaryotic chromosomes, and telomere shortening causes irreversible cell-cycle arrest through activation of the DNA-damage checkpoint. In this study, we found that deletion of PPH3, encoding a 2A-like protein phosphatase, accelerated telomere-shortening-mediated senescence without affecting normal telomere length or the telomere erosion rate in Saccharomyces cerevisiae. Moreover, the loss of PPH3 increased sensitivity to telomere dysfunction.

Reversible DNA damage checkpoint activation at the presenescent stage in telomerase-deficient cells of Saccharomyces cerevisiae.

The telomere protects the ends of eukaryotic linear chromosomes, and its shortening or erosion is recognized as DNA damage, leading to loss of proliferation activity and, thus, cellular senescence at the population level. Here, using a GFP-based DNA damage checkpoint marker suited for single-cell observation of Saccharomyces cerevisiae cells, we correlated the checkpoint status of telomere-shortened cells with their behavior. We show that some cells possessing short telomeres retain proliferation capacity even after the DNA damage checkpoint is activated.