Example of single-cell time-Lapse movie: Many eukaryotic promoters contain nucleosome-depleted-regions (NDRs), but the function of NDR is not very clear. By perturbing the nucleosome coverage on certain cell-cycle regulated promoters and probing the corresponding transcriptional activity in single-cell time-lapse microscopy, we discovered that promoters containing NDRs lead to reliable, once-per-cycle gene activation (movie 1 below). In striking contrast, promoters lacking NDRs induce stochastic, “on / off” activation in individual cell cycles, which displays short-term memory, or epigenetic inheritance, from the mother cycle (movie 2).