Replication origins are attached to the nuclear skeleton (original) (raw)

DNA fragments containing replication origins (oriDNA) were isolated from a chicken erytbroblast cell line by a modified procedure of Zannis-Hadjopoulos et al. /1, 2/ and studied in the renaturation reaction driven by either total or nuclear matrix DNA (nmDNA) from the same cells or from mature erythrocytes. We found that the unique sequences of nmlNA from erythroblasts (5 kb long) represented a specific subset of sequences constituting about a quarter of total DNA unique sequences, while the erythrocyte nmDNA 5 kb fragments constitute only about one tenth of total lunique DNA and all are recovered among erythroblast nmDNA. Virtually all oriDNA sequences are present in the fraction of erytbrocyte nmDNA. Thereafter, the putative positions of replication origins within the oL -globine gene domain have been mapped by hybridization experiments. They were found to coincide with the previously established positions of permanent sites of DNA attachment to the nuclear matrix.