All rb-bands display delayed replication in salivary gland polytene chromosomes and correspond to local minima on replication profiles for cell cultures.

<p><b>(A)</b> The replication pattern in salivary gland polytene chromosomes with all rb-bands labeled by PCNA in the region 43F-46B of polytene chromosome 2R as an example. The very existence of a pattern like this suggests that rb-bands are replicated later than the intervals between them. <b>(B, C)</b> Locations of rb-bands scaled to the genome map (B) and replication profiles in the cell cultures in comparison: data on KC, Cl8, S2 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195207#pone.0195207.ref033" target="_blank">33</a>], and BG3 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195207#pone.0195207.ref050" target="_blank">50</a>] (C) suggest that local minima on replication profiles for the cell cultures fall within rb-bands. This in turn suggests that rb-bands replicate later than their flanking regions. <b>(D)</b> Distribution of ORC2 peaks in Kc cells and in salivary glands [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195207#pone.0195207.ref051" target="_blank">51</a>] shows typical zones of low peak density in rb-bands and a prominent ORC2 signal confined to the regions between the rb-bands.