Checkpoint independence of most DNA replication origins in fission yeast.

Background: In budding yeast, the replication checkpoint slows progress through S phase by inhibiting replication origin firing. In mammals, the replication checkpoint inhibits both origin firing and replication fork movement. To find out which strategy is employed in the fission yeast, Schizosaccharomyces pombe, we used microarrays to investigate the use of origins by wild-type and checkpoint-mutant strains in the presence of hydroxyurea (HU), which limits the pool of deoxyribonucleoside triphosphates (dNTPs) and activates the replication checkpoint.

The Chinese hamster dihydrofolate reductase replication origin decision point follows activation of transcription and suppresses initiation of replication within transcription units.

Chinese hamster ovary (CHO) cells select specific replication origin sites within the dihydrofolate reductase (DHFR) locus at a discrete point during G1 phase, the origin decision point (ODP). Origin selection is sensitive to transcription but not protein synthesis inhibitors, implicating a pretranslational role for transcription in origin specification. We have constructed a DNA array covering 121 kb surrounding the DHFR locus, to comprehensively investigate replication initiation and transcription in this region.

Klenow exo-, as opposed to exo+, traverses through G-G:C triplex by melting G-G base pairs.

G-G base-paired hairpin DNA structures on template strands offer potential "road-blocks" to a traversing polymerase. Klenow polymerase (exo+) pauses while replicating through G-G base-paired hairpin DNA due to the generation of G-G:C triplex. However, exonuclease-deficient Klenow traverses through de novo generated G-G:C triplexes leading to full-length C:G duplexes.

A novel approach for uniform (13)C and (15)N labeling of DNA for NMR studies.

A novel method is proposed for large-scale synthesis of (13)C- and (15)N-labeled DNA for NMR studies. In this methodology, endonuclease-sensitive repeat amplification (ESRA), a modified PCR strategy, has been used to amplify tandem repeats of the target DNA sequence. The design of the template is such that restriction enzyme (RE) sites separate repeats of the target sequence.