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Fig. 6 | BMC Genomics

Fig. 6

From: Dynamic changes in ORC localization and replication fork progression during tissue differentiation

Fig. 6

Relationship between ORC location and underreplication domains. a, b Models for the hypothesis of underreplication resulting from inhibition of replication fork progression. It is established that UR regions are largely repressed for ORC binding and thus replication initiation (ORC sites in red). Replication forks produced from flanking origins can cross into the potential URs. a Stochastic fork stalling would result in a gradient of decreased copy number, with the lowest relative copy number at the center of the UR region. b Destabilization of forks to generate double-strand breaks (yellow stars) could also account for the decreased copy number gradient. c At genomic regions where SUUR or other replication fork inhibitors do not act, replication forks from flanking origins can fully replicate the domain. d, e Relationship between the widths of ORC-free zones and the URs. d For each ORC-free UR in the larval fat body (FB), the nearest ORC binding sites to the left and right of the UR midpoint were determined and the distance between these sites was calculated as the ORC-free zone and compared to the width of the UR. e Widths of ORC-free zones were calculated using late-3rd instar salivary gland (SG) ORC2 ChIP-Seq data [8] relative to ORC-free larval SG UR widths. In all analyses, URs in pericentric heterochromatin regions were omitted

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