Fig. 7

Hyperacetylated Microtus cabrerae cells show a stronger increase in genomic DNA in early S-phase and a decrease in the genome duplication rate. a The DNA content frequency analysis was performed by DAPI intensity measurements in treated and untreated cells, which were categorized into their respective S-phase substage according to their replication pattern. Box plots depict S-phase substages from early S to late S for both untreated and treated samples. HDACi-treated samples are indicated by the red-framed box. The DNA content of treated cells is in early S-phase significantly increased in comparison with untreated cells. Statistical significance was tested using the Wilcoxon test, comparing untreated and HDACi-treated Microtus cabrerae cells. ***P < 0.001. b The genome duplication time was calculated from the DNA content data. As after S-phase 100% of the DNA is replicated, the genome duplication per substage can be estimated. In treated cells (red-framed box), 50% of the genome was already replicated during early S-phase, whereas only 37% of the genome was replicated in early S in control samples. 38% of the genome was replicated in mid-S-phase in control cells. In contrast, only 24% of the genome was replicated in mid-S-phase in HDACi-treated cells. c When combining these genome duplication data with the measured DNA replication substage durations of Fig. 4a, we were able to measure the % of genome increase per hour, an indicator of replication speed. The values showed that the % of genome replicated in 1 h was decreased in treated samples, in particular, of facultative heterochromatin