Eucaryotic DNA: Organization of the genome for replication

Xrep, a plasmid-stimulating X chromosomal sequence bearing similarities to the BK virus replication origin and viral enhancers

“…In contrast with the relative, low number of SV40 or BK viral-like sequences found in primate genomes, there is evidence that the number of replication origins is in the thousands (32).…”

“…For example, a chromosomal replication origin which replicates once per cell cycle would be expected to differ from a viral replication origin due to the former's more stringent requirements in tissue-specific replication timing (32).…”

Foreword: Eukaryotic DNA replication: is time of the essence?

“…Traditionally, active replicons were labelled with 3 H-thymidine and visualised by autoradiography. Studying synthesis in mammalian systems, this approach revealed that adjacent replicons were often activated together in small groups (Hand 1978; for an excellent historical perspective, see Gilbert 2007). This general theme of synthetic co-activation of groups of replicons was emphasised when Nakamura et al (1986) showed that the active sites in nuclei contained synthetic hotspots where many replicon are synthesised together.…”

High-resolution banding: present aspects

“…The reduction in DNA synthesis corresponds to the period when the replication complex shifts from early to late replicons (Reddy and Pardee, 1980). Clusters of early and late replicons alternate and create replication patterns (Hand, 1978). The clusters may contain up to 100 individual replicons giving a DNA content which corresponds to a chromosomal band (Hand, 1978).…”

“…Clusters of early and late replicons alternate and create replication patterns (Hand, 1978). The clusters may contain up to 100 individual replicons giving a DNA content which corresponds to a chromosomal band (Hand, 1978). In premature chromosome condensation (PCC) experiments, Lau and Arrighi (1981) (Yunis and Bahr, 1979).…”