BACKGROUND The origin recognition complex (ORC) and the minichromosome maintenance (MCM) protein complex were initially discovered in yeast and shown to be essential for DNA replication. Homologues of ORC and MCM proteins exist in higher eukaryotes, including Xenopus. The Xenopus MCM proteins and the Xenopus homologues of Saccharomyces cerevisiae Orc 1p and Orc2p (XOrc1 and XOrc2) have recently...

In higher eukaryotes, the origin recognition complex (ORC) lacks sequence-specific DNA binding, and it remains unclear what other factors specify an origin of DNA replication. The Epstein-Barr virus origin of plasmid replication (OriP) recruits ORC, but the precise mechanism of ORC recruitment and origin activation is not clear. We now show that ORC is recruited selectively to the dyad symmetry...

In all eukaryotic cells, origins of DNA replication are characterized by the binding of the origin recognition complex (ORC). How ORC is positioned to sites where replication initiates is unknown, because metazoan ORC binds DNA without apparent sequence specificity. Thus, additional factors might be involved in ORC positioning. Our experiments indicate that a family member of the high-mobility ...

The origin recognition complex (ORC) has an important function in determining the initiation sites of DNA replication. In higher eukaryotes, ORC lacks sequence-specific DNA binding, and the mechanisms of ORC recruitment and origin determination are poorly understood. ORC is recruited with high efficiency to the Epstein-Barr virus origin of plasmid replication (OriP) through a complex mechanism ...

The role of the origin recognition complex (ORC) was investigated in replication initiation and in silencing. Temperature-sensitive mutations in ORC genes caused defects in replication initiation at chromosomal origins of replication, as measured by two-dimensional (2-D) origin-mapping gels, fork migration analysis, and plasmid replication studies. These data were consistent with ORC functionin...

In eukaryotes, DNA replication requires the origin recognition complex (ORC), a six-subunit assembly that promotes replisome formation on chromosomal origins. Despite extant homology between certain subunits, the degree of structural and organizational overlap between budding yeast and metazoan ORC has been unclear. Using 3D electron microscopy, we determined the subunit organization of metazoa...

The origin recognition complex (ORC) specifies replication origin location. The Saccharomyces cerevisiae ORC recognizes the ARS (autonomously replicating sequence) consensus sequence (ACS), but only a subset of potential genomic sites are bound, suggesting other chromosomal features influence ORC binding. Using high-throughput sequencing to map ORC binding and nucleosome positioning, we show th...

In eukaryotes the sites for the initiation of chromosomal DNA replication are believed to be determined in part by the binding of a heteromeric origin recognition complex (ORC) to DNA. We have cloned the genes encoding the subunits of the Drosophila ORC. Each of the genes is unique and can be mapped to discrete chromosomal locations implying that the pattern and developmental regulation of orig...

Crossbred wethers (72; 31 k 0.5 kg) were used to determine effects of different grass sources and qualities on visceral organ mass after 42 and 84days. Wethers consumed ad libitum bermudagrass (BER; Cynodon dactylon) (H, 24-day regrowth; M, 42-day regrowth; L, full-season growth) or orchardgrass (ORC; Dactylis glomeruta) (H, late vegetative to pre-anthesis; M, post-anthesis; L, seed in dough st...

Oral contraceptive (ORC)-related depression and irritability are among the most commonly reported drug-induced psychiatric symptoms. To investigate the etiological role of genetic factors in ORC-related symptoms, we studied questionnaire responses in 715 monozygotic and 416 dizygotic volunteer twin pairs concordant for ORC usage. Biometrical genetic analysis indicated that the liability to ORC-...