Tet-STH1 strain was split into two liquid cultures and grown over night in the presence and absence of doxocycline Tet-STH1 (+D), Tet-STH1 (−D). Cells were arrested at the G2/M phase of cell cycle. Spheroplasts were isolated, treated with MNase and genomic DNA was purified, separated on agarose gel and stained with ethidium bromide. A. MNase digestion patterns in wild type Tet-STH1(−D) and mutant Tet-STH1(+D) synchronized at G2/M phase of the cell cycle. Gel shows representative data of at least two independent experiments. M: DNA size standard, T: tri-nucleosome, D: di-mucleosome, M: mono-nucleosome. B. Quantitative analysis of MNase accessibility expressed as the ratio of mono- to tri-nucleosome signal at different concentrations of MNase. C. Band intensity profiles of the 40U MNase lanes for Tet-STH1(−D) and Tet-STH1(+D).