Identification of primary initiation sites for DNA replication in the hamster dihydrofolate reductase gene initiation zone.

ABSTRACT: Mammalian replication origins appear paradoxical. While some studies conclude that initiation occurs bidirectionally from specific loci, others conclude that initiation occurs at many sites distributed throughout large DNA regions. To clarify this issue, the relative number of early replication bubbles was determined at 26 sites in a 110-kb locus containing the dihydrofolate reductase (DHFR)-encoding gene in CHO cells; 19 sites were located within an 11-kb sequence containing ori-beta. The ratio of approximately 0.8-kb nascent DNA strands to nonreplicated DNA at each site was quantified by competitive PCR. Nascent DNA was defined either as DNA that was labeled by incorporation of bromodeoxyuridine in vivo or as RNA-primed DNA that was resistant to lambda-exonuclease. Two primary initiation

SUBMITTER: Kobayashi T 

PROVIDER: S-EPMC108908 | biostudies-literature | 1998 Jun

REPOSITORIES: biostudies-literature