Distribution of ORCs, GINS and EdU on extended chromatin fibers. (A) Only ORC1 (red signal) is found on the chromatin fiber; there is no GINS or EdU signal on this fiber. (B and C) Both ORCs (red signal) and GINS (blue signal) can be found along the fiber but no EdU. (D and E) ORCs, GINS complexes and EdU (green signal) are all present. The localization of ORCs, GINS and DNA replication tracks on these fibers suggests that ORCs are loaded on the chromatin first, then GINS, followed by DNA replication. Bars ≅ 25 μm (≅ 400 kb; bottom right of each panel).