High-resolution validation of newly identified ORIs. Q-ChIP of ORC1 (A) and MCM5 (B) binding to the PRKDC ORI, eight newly identified ORC1 peaks (A–H), and four control regions (C1–C4), using anti-ORC1, anti-MCM5, or anti-Flag (Mock) antibodies and chromatin of low-density fractions. (Error bars) SD; n = 2. The position of Q-PCR probes, relative to the summit of ORC1 peaks, is shown at the bottom of A. (Scale bar) 1 kb. (C) Distribution of DNA fragments from two ORC1 peaks (C, G) and their flanking regions (+5 and −1.5 kb, respectively). (D) NSA assay of the PRKDC ORI, A–K ORC1 sites, and their flanking regions (distance from the probe within the ORC1 peak, in kilobases, is shown below). The amplitude of the I–K peaks is shown in Supplemental Figure S3. The amounts of SNSs are relative to PRKDC ORI (=1).