BIOL 483 Lecture Notes - Lecture 87: X-Inactivation, Sonication, Immunoprecipitation
Genome wide many vs all: cross link dna, restriction enzyme digest, biotin labelling, ligation to make alpha shape, sonication. Tads don"t change much when looking at population of cells. Tads dissolve during mitosis, reestablished after replication (perhaps it"s a way to put genome together in orderly fashion) Tads are invariant between cell types (more variable in single cells), in response to cues, during evolution, rapidly reestablished after replication. Dna helix > chromatin fibre > chromatin loops > tads > chromatin compartments. Tads are defined by triangles along the diagonal and there are low signal regions between the. Loop comes out until 2 ctcf (forward ctcf, reverse ctcf) come close tgt to form boundary by blocking entrance of cohesin. If enhancer and promoter in different tads, enhancer cannot target promoter in another tad. If promoter and enhancer in same loop -> can interact. To test x inactivation 3d analysis of xic, can manipulate tad boundaries and loops.