Replication termination structures accumulate at <i>RFB</i> and at other barriers in the rDNA in <i>sgs1Δtop2</i>^<i>ts</i> cells.

<p>(A) Schematic illustration representing the expected Neutral-Alkaline 2D gel migration behavior of replicating rDNA corresponding to the 4.577bp <i>Bgl</i>IIB-fragment encompassing the <i>RFB</i> (grey box) with reference to the migration of the corresponding DNA in Neutral-Neutral 2D gels. Migration of the DNA strands shown with black lines is indicated. <i>RFB</i> as well as the positions of the 1N and 2N dots are indicated. (B) Genomic DNA was isolated from wt, <i>sgs1Δtop2</i>^<i>ts</i>, <i>sgs1Δtop2</i>^<i>ts</i><i>pif1Δ</i> and <i>sgs1Δtop2</i>^<i>ts</i><i>fob1Δ</i> cells at the indicated time points after release from α-factor, digested with <i>Bgl</i>II, and subjected to Neutral-Alkaline 2D gel analysis and Southern blotting using the P3 probe (<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005697#pgen.1005697.g002" target="_blank">Fig 2C</a>). FACS profiles of samples taken throughout the experiments are shown to the right. (C) Quantification of forks converging at <i>RFB</i> at the indicated time points, where the signal at time point 0 is set to 1. Error bars represent STDEV from two to four independent experiments. (D) Quantification of forks converging outside <i>RFB</i> (“<”-smear) at the indicated time points, where the signal at time point 0 is set to 1. Error bars represent STDEV from two to four independent experiments.