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Fig. 1 | BMC Genomics

Fig. 1

From: A streamlined tethered chromosome conformation capture protocol

Fig. 1

Overview of RTCC protocol. a Diagram shows a schematic description of steps from a crude tissue homogenate to a proximity sequencing library (details provided in the Methods section). For our studies (using C. elegans), animals flash-frozen in liquid nitrogen were finely ground using either mortar and pestle or using an electric drill with “Cellcrusher” drill-bit and “Cellcrusher” base held at liquid nitrogen temperature and treated with formaldehyde to covalently cross-link proteins to each other and to DNA (red and purple strands, threaded through the blue amorphous complex, representing proteins). (1) Chromatin is solubilized with detergent and proteins were non-specifically biotinylated (orange balls on sticks). (2) DNA was digested with a restriction enzyme that generates 5’ overhangs. (3) Cross-linked complexes were immobilized at a very low density on the surface of streptavidin-coated magnetic beads (grey color arc) through the biotinylated proteins, while the non-cross-linked DNA fragments were removed. (4) 5′ overhangs were filled in using DNA polymerase and a nucleotide mixture containing biotin-14-dCTP (orange balls on sticks) to generate blunt ends. (5) Blunt DNA ends were ligated. (6) Cross-linking was reversed and DNA was purified. (7) The DNA was fragmented and tagged (light blue strands) using Nextera tagmentase. (8) DNA fragments containing biotinylated CTP were selected on streptavidin-coated beads. This selects for ligation junctions and DNA molecules biotinylated at their terminus. (9) A Sequencing library was generated via PCR using the Nextera [http://www.illumina.com/products/nextera_dna_library_prep_kit.html] adaptors introduced at step 7. This amplification step should provide a substantial enrichment for ligation junctions, since molecules that were biotinylated solely on their termini would carry a Nextera adaptor only on one side. b RTCC protocol timeline

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