Figure 1: Cajal bodies favourably interact with highly expressed U gene and histone gene loci.

(a) Approximate chromosomal location of BAC DNA FISH probe target sequences used in this study. Blue text denotes CB-proximal (4C-positive) gene loci and black text denotes non-CB-proximal (4C-negative) gene loci. (b) Six-colour fluorescent microscopy analysis of four CTs, CB-interacting gene locus detected by DNA FISH and CB localization visualized by CB marker protein, coilin, in aneuploid HeLa (CB-positive) and primary diploid D551 (CB-negative) cells. Scale bar, 2 μm. (c) Six-colour fluorescent microscopy analysis of Cajal body-interacting gene loci by DNA FISH and coilin immunostaining in HeLa cells. (d) Six-colour microscopy analysis of CB-interacting and CB-independent negative-control gene loci by DNA FISH and coilin immunostaining in HeLa cells. (e) Box and whisker plot of frequencies of CT–CB association interactions (manually scored by proximity to CBs). Error bars depict s.d. and scores represent assessment of at least 150 cells. (f) Histogram displaying the frequency of interaction between one CB and (up to four) CTs (manually scored by proximity to CBs). Error bars depict s.d. and scores represent assessment of at least 150 cells. (g) Box and whisker plot of frequencies of DNA FISH loci–CB association interactions (manually scored by proximity to CBs). Error bars depict s.d. and scores represent assessment of at least 150 cells. (h) Six-colour microscopy analysis of CB-interacting loci by DNA FISH and coilin immunostaining in human primary diploid foreskin D551 cells, human primary diploid cervical epithelial cells (HCvEpC; lacking CBs) and (i) HeLa cells following CB disassembly by TCAB1 or USPL1 knockdown.