SC Dynamics at Steady State Figure 4. Sites of initial Zip1 entry into full-length SC exhibit no preference for centromere over chromosomal arm sites. (A) Meiotic surface spread chromosomes from K39 strains expressing the centromere marker Ctf19-MYC (red) and Zip1-GFP (green) fixed after 45 minutes of induction. DNA (blue) and anti-Zip1 (red) is shown in the second row. White arrows indicate centromeres with an overlapping Zip1-GFP focus, while arrowheads indicate centromeres devoid of Zip1-GFP. Scale, 1 mm. (B) Zip1-GFP in relation to centromere distribution data from nuclei with earliest Zip1-GFP incorporation events. The X axis of the scatterplot indicates the total number of short Zip1-GFP stretches in each nucleus (circles indicate values for individual nuclei), while the Y axis displays the fraction of these initial incorporation events that are adjacent to or overlapping a centromere. For most nuclei, fewer than half of the Zip1-GFP incorporation events localize with a centromere even when total incorporation events are small. (C) Pie graph displays Zip1-GFP and centromere relative distribution data for nuclei exhibiting robust Zip1-GFP incorporation after 45 minutes of induction. (These nuclei display a number of Zip1-GFP discrete events that outnumber centromeres.) Each color represents the fraction of centromeres in such nuclei associated with Zip1-GFP foci (blue), short stretches (0.35–0.5 mm) (pink), long stretches (.0.5 mm) (green). Centromeres displaying no Zip1-GFP are shown in purple. Actual numbers corresponding to each category are shown on the graph (black). doi:10.1371/journal.pgen.1002993.g004 PLOS Genetics | www.plosgenetics.org 7 October 2012 | Volume 8 | Issue 10 | e1002993