title: DNA replication origins fire stochastically in fission yeast.
abstract: DNA replication initiates at discrete origins along eukaryotic chromosomes. However, in most organisms, origin firing is not efficient; a specific origin will fire in some but not all cell cycles. This observation raises the question of how individual origins are selected to fire and whether origin firing is globally coordinated to ensure an even distribution of replication initiation across the genome. We have addressed these questions by determining the location of firing origins on individual fission yeast DNA molecules using DNA combing. We show that the firing of replication origins is stochastic, leading to a random distribution of replication initiation. Furthermore, origin firing is independent between cell cycles; there is no epigenetic mechanism causing an origin that fires in one cell cycle to preferentially fire in the next. Thus, the fission yeast strategy for the initiation of replication is different from models of eukaryotic replication that propose coordinated origin firing.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Prasanta K
authors.initials: PK
authors.lastname: Patel
authors.forename: Benoit
authors.initials: B
authors.lastname: Arcangioli
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Baker
authors.forename: Aaron
authors.initials: A
authors.lastname: Bensimon
authors.forename: Nicholas
authors.initials: N
authors.lastname: Rhind
mesh_terms: D004261:DNA Replication / Q000235:genetics*; D004271:DNA, Fungal / Q000096:biosynthesis* / Q000235:genetics*; D016681:Genome, Fungal / Q000235:genetics; D018741:Replication Origin / Q000235:genetics*; D016196:S Phase; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics; D013269:Stochastic Processes
chemical_list: D004271:DNA, Fungal; D029702:Schizosaccharomyces pombe Proteins; C400810:ura4 protein, S pombe