Validation of triples using PCR.
(a) Ten triples extracted from the KBM7-TM3C-1 library that have at least one of their three ends in the 40 kb region surrounding the imprinting control region (ICR) of IGF2 and H19 genes. These triples involve short- and long-range contacts within chromosome 11 which are all indicated by tick marks with coordinates in kilobases (kb) displayed only for long-range contacts. Interchromosomal contacts with other chromosomes are indicated by the chromosome identifier followed by the coordinate in megabases (Mb). Orientation of the displayed locus is in the direction of IGF2 and H19 transcription. (b) PCR verification of pairwise contacts from triples 3 and 5. One pair of forward/reverse primers is used for each gel (Additional file 1: Table S1).