title: Mapping sites where replication initiates in mammalian cells using DNA fibers.
abstract: DNA replication in mammalian chromosomes takes place as a unit of replicon clusters. Here we show a powerful method to detect replication origins and fork movement on DNA fibers from mammalian cells. Cells were loaded with nucleotide analogs, DNA fibers were prepared, and replicated DNA was detected. Using this approach, we could detect origins as close as 10 kb apart and found that the average size of replicon is smaller ( approximately 46 kb) than previously estimated. In addition, the procedure visualizes the complex structure of replicon clusters, e.g. sequential activation of origins in a cluster and flexible initiation sites in different cell cycles. Combined with fluorescence in situ hybridization, replication origins can be mapped in genomic loci including repetitive DNA and a single-copy gene.
authors.affiliation: Faculty of Bioresources, Mie University, 1515 Kamihama, Tsu, 514-8507, Japan.
authors.forename: S I
authors.initials: SI
authors.lastname: Takebayashi
authors.forename: E M
authors.initials: EM
authors.lastname: Manders
authors.forename: H
authors.initials: H
authors.lastname: Kimura
authors.forename: H
authors.initials: H
authors.lastname: Taguchi
authors.forename: K
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000818:Animals; D001483:Base Sequence / Q000235:genetics; D001973:Bromodeoxyuridine; D002455:Cell Division / Q000235:genetics*; D002478:Cells, Cultured; D002874:Chromosome Mapping / Q000379:methods*; D002875:Chromosomes / Q000235:genetics*; D004247:DNA / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D005333:Fetus; D017404:In Situ Hybridization, Fluorescence; D008322:Mammals / Q000235:genetics*; D051379:Mice; D009711:Nucleotides / Q000494:pharmacology; D016196:S Phase / Q000235:genetics; D014544:Uridine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D009711:Nucleotides; D004247:DNA; D001973:Bromodeoxyuridine; D014544:Uridine Triphosphate