The replication timing program of the Chinese hamster beta-globin locus is established coincident with its repositioning near peripheral heterochromatin in early G1 phase.

ABSTRACT: We have examined the dynamics of nuclear repositioning and the establishment of a replication timing program for the actively transcribed dihydrofolate reductase (DHFR) locus and the silent beta-globin gene locus in Chinese hamster ovary cells. The DHFR locus was internally localized and replicated early, whereas the beta-globin locus was localized adjacent to the nuclear periphery and replicated during the middle of S phase, coincident with replication of peripheral heterochromatin. Nuclei were prepared from cells synchronized at various times during early G1 phase and stimulated to enter S phase by introduction into Xenopus egg extracts, and the timing of DHFR and beta-globin replication was evaluated in vitro. With nuclei isolated 1 h after mitosis, neither locus was preferentially repl

SUBMITTER: Li F 

PROVIDER: S-EPMC1255917 | biostudies-literature | 2001 Jul

REPOSITORIES: biostudies-literature