FIGURE 4.

Association of Physarum H1 with DNA is reduced upon replication origin firing. A, experimental scheme. Plasmodia were harvested in the early S phase, in the late S phase, and in the early G₂ phase followed by ChIP analyses with immunopurified H1 antibodies. B, loss of H1 increases DNA accessibility. Accessibility of DNA was assessed by micrococcal nuclease digestion. The nuclei were isolated from macroplasmodia untreated and treated with siRNA, and micrococcal nuclease digestion was performed as previously described (16) for 0.5, 1, 3, 5, and 7 min. C, H1 is released from replicating Lav2.1. H1 Input and anti-H1 immunoprecipitated DNA was assayed for the presence of the Lav2.1 replicon in untreated (–) and H1 siRNA-treated (+) cells.