Abstract
Magnesium chloride and polyamines stabilize DNA and chromatin. Furthermore, they can induce nucleosome aggregation and chromatin condensation in vitro. To determine the effects of elevating the cation concentrations in the nucleus of a living cell, we microinjected various concentrations of mono-, di- and polyvalent cation solutions into the nuclei of mouse embryonic stem (ES) cells and traced their fates. Here, we show that an elevation of either MgCl2, spermidine or spermine concentration in the nucleus exerts a significant effect on mouse ES cells, and can differentiate a certain population of the cells into trophectoderm, a lineage that mouse ES cells do not normally generate, or endoderm. It is hypothesized that the cell differentiation was most probably caused by the condensation of chromatin including the Oct3/4 locus, which was induced by the elevated concentrations of these cations.