BLM and PICH in Centromere Disjunction Figure 3. Structural defects at the centromeres in BLM-and PICH-deficient cells. (A) FISH with the CEN-8 probe (green) on metaphase BS and GFP-BLM cells. Chromosomes are visualized by DAPI staining (red). Bar = 5 mm. (B) Comparison of the volume of the centromeric FISH signal detected on chromosomes 8 from GFP-BLM (defined as 1) and BS cells (left panel) and from GFP-BLM cells with (siPICH) and without (siCtrl) PICH downregulation (defined as 1) (right panel). We analyzed 45 metaphase cells from three independent experiments for each cell line. (C) GFP-BLM cells (left panel) and BS cells (right panel) were processed for electron microscopy. Scale bar = 1 mm. Inset: schematic diagram of the regions of interest (white squares) (MT: microtubules, KT: kinetochore outer plate and CC: centromeric chromatin). Eight centromeres from two independent experiments were analyzed. doi:10.1371/journal.pone.0033905.g003 PLoS ONE | www.plosone.org 5 April 2012 | Volume 7 | Issue 4 | e33905