DNA Replication in the Chromosomes of the Chicken, Gallus Domesticus

1973 ◽  
Vol 13 (3) ◽  
pp. 821-839
Author(s):  
PAMELA W. McFARLANE ◽  
H. G. CALLAN
Keyword(s):  
Tissue Culture ◽  
Dna Replication ◽  
S Phase ◽  
Gallus Domesticus ◽  
Chromosomal Dna ◽  
The Mean ◽  
The Times

DNA fibre autoradiography has been used to study the replication of chromosomal DNA from chicken cells in tissue culture at 37 °C. The S-phase is estimated to be about 7.5 h. Replication proceeds in the manner first described by Huberman & Riggs. Tandemly arranged units replicate bi-directionally from fork-like growing points, the times of initiation of individual replicating sections being staggered. Evidence against the existence of defined termini is presented. The rate of replication in these chicken cells is some 25-30 µm/h one-way. The mean interval between adjacent initiation points for replication is 63 µm, with a range of some 25-145 µm. Although initiation intervals vary in length, neighbouring intervals tend to be similar in length.

scholarly journals Effects of temperature on the replication of chromosomal DNA of Xenopus laevis cells

1983 ◽  
Vol 59 (1) ◽  
pp. 1-12
Author(s):  
A.A. Al-Saleh
Keyword(s):  
Tissue Culture ◽  
Dna Replication ◽  
Xenopus Laevis ◽  
Replication Forks ◽  
Chromosomal Dna ◽  
The Mean ◽  
Effects Of Temperature

DNA fibre autoradiography has been used to study the effects of temperature on the replication of chromosomal DNA of Xenopus laevis cells in tissue culture at 18, 23 and 28 degrees C. Pulse/stepdown labelling shows that the DNA replicates bidirectionally. Origin-to-origin distances (initiation intervals) vary, but the range of and the mean initiation intervals at all three temperatures are much the same. The mean interval between initiation points is of the order of 60 to 66 microns. Staggering of initiation is evident at all three temperatures. Evidence against the existence of replication termini is provided. The rates of progress of DNA replication forks are 6 microns/h at 18 degrees C, 10 microns/h at 23 degrees C and 16 microns/h at 28 degrees C.

scholarly journals Both cyclin A and cyclin E have S-phase promoting (SPF) activity in Xenopus egg extracts

1996 ◽  
Vol 109 (6) ◽  
pp. 1555-1563 ◽  
Author(s):  
U.P. Strausfeld ◽  
M. Howell ◽  
P. Descombes ◽  
S. Chevalier ◽  
R.E. Rempel ◽  
...  
Keyword(s):  
Dna Replication ◽  
Cyclin E ◽  
Cyclin A ◽  
Early Embryo ◽  
S Phase ◽  
Chromosomal Dna ◽  
Cyclin E1 ◽  
Egg Extracts ◽  
High Concentrations ◽  
Xenopus Egg Extracts

Extracts of activated Xenopus eggs in which protein synthesis has been inhibited support a single round of chromosomal DNA replication. Affinity-depletion of cyclin dependent kinases (Cdks) from these extracts blocks the initiation of DNA replication. We define ‘S-phase promoting factor’ (SPF) as the Cdk activity required for DNA replication in these Cdk-depleted extracts. Recombinant cyclins A and E, but not cyclin B, showed significant SPF activity. High concentrations of cyclin A promoted entry into mitosis, which inhibited DNA replication. In contrast, high concentrations of cyclin E1 promoted neither nuclear envelope disassembly nor full chromosome condensation. In the early embryo cyclin E1 complexes exclusively with Cdk2 and cyclin A is complexed predominantly with Cdc2; only later in development does cyclin A associate with Cdk2. We show that baculovirus-produced complexes of cyclin A-Cd2, cyclin A-Cdk2 and cyclin E-Cdk2 could each provide SPF activity. These results suggest that although in the early Xenopus embryo cyclin E1-Cdk2 is sufficient to support entry into S-phase, cyclin A-Cdc2 provides a significant additional quantity of SPF as its levels rise during S phase.

scholarly journals The dynamics of replication licensing in live Caenorhabditis elegans embryos

2012 ◽  
Vol 196 (2) ◽  
pp. 233-246 ◽  
Author(s):  
Remi Sonneville ◽  
Matthieu Querenet ◽  
Ashley Craig ◽  
Anton Gartner ◽  
J. Julian Blow
Keyword(s):  
Caenorhabditis Elegans ◽  
Dna Replication ◽  
Dna Binding ◽  
Feedback Loop ◽  
Origin Recognition Complex ◽  
S Phase ◽  
Chromosomal Dna ◽  
M Phase ◽  
Prereplicative Complex

Accurate DNA replication requires proper regulation of replication licensing, which entails loading MCM-2–7 onto replication origins. In this paper, we provide the first comprehensive view of replication licensing in vivo, using video microscopy of Caenorhabditis elegans embryos. As expected, MCM-2–7 loading in late M phase depended on the prereplicative complex (pre-RC) proteins: origin recognition complex (ORC), CDC-6, and CDT-1. However, many features we observed have not been described before: GFP–ORC-1 bound chromatin independently of ORC-2–5, and CDC-6 bound chromatin independently of ORC, whereas CDT-1 and MCM-2–7 DNA binding was interdependent. MCM-3 chromatin loading was irreversible, but CDC-6 and ORC turned over rapidly, consistent with ORC/CDC-6 loading multiple MCM-2–7 complexes. MCM-2–7 chromatin loading further reduced ORC and CDC-6 DNA binding. This dynamic behavior creates a feedback loop allowing ORC/CDC-6 to repeatedly load MCM-2–7 and distribute licensed origins along chromosomal DNA. During S phase, ORC and CDC-6 were excluded from nuclei, and DNA was overreplicated in export-defective cells. Thus, nucleocytoplasmic compartmentalization of licensing factors ensures that DNA replication occurs only once.

Chromosomal DNA replication initiates at the same origins in meiosis and mitosis

1994 ◽  
Vol 14 (5) ◽  
pp. 3524-3534
Author(s):  
I Collins ◽  
C S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
S Phase ◽  
Replication Origins ◽  
Chromosomal Dna ◽  
Chromosomal Replication ◽  
Yeast Saccharomyces Cerevisiae ◽  
Autonomously Replicating Sequence ◽  
Ars Elements ◽  
Chromosome Iii

Autonomously replicating sequence (ARS) elements are identified by their ability to promote high-frequency transformation and extrachromosomal replication of plasmids in the yeast Saccharomyces cerevisiae. Six of the 14 ARS elements present in a 200-kb region of Saccharomyces cerevisiae chromosome III are mitotic chromosomal replication origins. The unexpected observation that eight ARS elements do not function at detectable levels as chromosomal replication origins during mitotic growth suggested that these ARS elements may function as chromosomal origins during premeiotic S phase. Two-dimensional agarose gel electrophoresis was used to map premeiotic replication origins in a 100-kb segment of chromosome III between HML and CEN3. The pattern of origin usage in premeiotic S phase was identical to that in mitotic S phase, with the possible exception of ARS308, which is an inefficient mitotic origin associated with CEN3. CEN3 was found to replicate during premeiotic S phase, demonstrating that the failure of sister chromatids to disjoin during the meiosis I division is not due to unreplicated centromeres. No origins were found in the DNA fragments without ARS function. Thus, in both mitosis and meiosis, chromosomal replication origins are coincident with ARS elements but not all ARS elements have chromosomal origin function. The efficiency of origin use and the patterns of replication termination are similar in meiosis and in mitosis. DNA replication termination occurs over a broad distance between active origins.

scholarly journals Chromosomal DNA replication initiates at the same origins in meiosis and mitosis.

1994 ◽  
Vol 14 (5) ◽  
pp. 3524-3534 ◽  
Author(s):  
I Collins ◽  
C S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
S Phase ◽  
Replication Origins ◽  
Chromosomal Dna ◽  
Chromosomal Replication ◽  
Yeast Saccharomyces Cerevisiae ◽  
Autonomously Replicating Sequence ◽  
Ars Elements ◽  
Chromosome Iii

Autonomously replicating sequence (ARS) elements are identified by their ability to promote high-frequency transformation and extrachromosomal replication of plasmids in the yeast Saccharomyces cerevisiae. Six of the 14 ARS elements present in a 200-kb region of Saccharomyces cerevisiae chromosome III are mitotic chromosomal replication origins. The unexpected observation that eight ARS elements do not function at detectable levels as chromosomal replication origins during mitotic growth suggested that these ARS elements may function as chromosomal origins during premeiotic S phase. Two-dimensional agarose gel electrophoresis was used to map premeiotic replication origins in a 100-kb segment of chromosome III between HML and CEN3. The pattern of origin usage in premeiotic S phase was identical to that in mitotic S phase, with the possible exception of ARS308, which is an inefficient mitotic origin associated with CEN3. CEN3 was found to replicate during premeiotic S phase, demonstrating that the failure of sister chromatids to disjoin during the meiosis I division is not due to unreplicated centromeres. No origins were found in the DNA fragments without ARS function. Thus, in both mitosis and meiosis, chromosomal replication origins are coincident with ARS elements but not all ARS elements have chromosomal origin function. The efficiency of origin use and the patterns of replication termination are similar in meiosis and in mitosis. DNA replication termination occurs over a broad distance between active origins.

scholarly journals Negative Regulation of Cdc18 DNA Replication Protein by Cdc2

1998 ◽  
Vol 9 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Antonia Lopez-Girona ◽  
Odile Mondesert ◽  
Janet Leatherwood ◽  
Paul Russell
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Fission Yeast ◽  
Phosphorylation Site ◽  
Constitutive Expression ◽  
S Phase ◽  
Negative Regulation ◽  
Chromosomal Dna

Fission yeast Cdc18, a homologue of Cdc6 in budding yeast and metazoans, is periodically expressed during the S phase and required for activation of replication origins. Cdc18 overexpression induces DNA rereplication without mitosis, as does elimination of Cdc2-Cdc13 kinase during G2 phase. These findings suggest that illegitimate activation of origins may be prevented through inhibition of Cdc18 by Cdc2. Consistent with this hypothesis, we report that Cdc18 interacts with Cdc2 in association with Cdc13 and Cig2 B-type cyclins in vivo. Cdc18 is phosphorylated by the associated Cdc2 in vitro. Mutation of a single phosphorylation site, T104A, activates Cdc18 in the rereplication assay. The cdc18-K9 mutation is suppressed by a cig2 mutation, providing genetic evidence that Cdc2-Cig2 kinase inhibits Cdc18. Moreover, constitutive expression of Cig2 prevents rereplication in cells lacking Cdc13. These findings identify Cdc18 as a key target of Cdc2-Cdc13 and Cdc2-Cig2 kinases in the mechanism that limits chromosomal DNA replication to once per cell cycle.

scholarly journals Xenopus Cdc7 function is dependent on licensing but not on XORC, XCdc6, or CDK activity and is required for XCdc45 loading

2000 ◽  
Vol 14 (12) ◽  
pp. 1528-1540
Author(s):  
Pedro Jares ◽  
J. Julian Blow
Keyword(s):  
Dna Replication ◽  
Origin Recognition Complex ◽  
Protein Complexes ◽  
Present Report ◽  
S Phase ◽  
Chromosomal Dna ◽  
Minichromosome Maintenance ◽  
Initiation Of Replication ◽  
Sequential Binding

The assembly and disassembly of protein complexes at replication origins play a crucial role in the regulation of chromosomal DNA replication. The sequential binding of the origin recognition complex (ORC), Cdc6, and the minichromosome maintenance (MCM/P1) proteins produces a licensed replication origin. Before the initiation of replication can occur, each licensed origin must be acted upon by S phase-inducing CDKs and the Cdc7 protein kinase. In the present report we describe the role of Xenopus Cdc7 (XCdc7) in DNA replication using cell-free extracts of Xenopus eggs. We show that XCdc7 binds to chromatin during G1 and S phase. XCdc7 associates with chromatin only once origins have been licensed, but this association does not require the continued presence of XORC or XCdc6 once they have fulfilled their essential role in licensing. Moreover, XCdc7 is required for the subsequent CDK-dependent loading of XCdc45 but is not required for the destabilization of origins that occurs once licensing is complete. Finally, we show that CDK activity is not necessary for XCdc7 to associate with chromatin, induce MCM/P1 phosphorylation, or perform its essential replicative function. From these results we suggest a simple model for the assembly of functional initiation complexes in the Xenopus system.

Distinct roles of cdk2 and cdc2 in RP-A phosphorylation during the cell cycle

1993 ◽  
Vol 106 (3) ◽  
pp. 983-994 ◽  
Author(s):  
F. Fang ◽  
J.W. Newport
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Binding ◽  
Dna Binding Protein ◽  
Model System ◽  
S Phase ◽  
Chromosomal Dna ◽  
Cdc2 Kinase ◽  
Single Stranded Dna

RP-A is a single-stranded DNA-binding protein, which has been shown to be required for DNA replication using an SV40 model system. The protein has also been shown to be phosphorylated at the G1-S phase transition. Using Xenopus cell-free extracts we have investigated the role of RP-A in nuclear replication and characterized the kinases and conditions that lead to phosphorylation of RP-A during the cell cycle. By immunodepleting RP-A from Xenopus extracts we have shown that RP-A is essential for replication of chromosomal DNA. Our results show that, during S phase, only that RP-A which is associated with nuclei is phosphorylated. Furthermore our results indicate that during S phase RP-A is only phosphorylated when associated with single-stranded DNA. By immunodepleting cdk2 kinase we show that cdk2 kinase is required for the observed phosphorylation of RP-A in nuclei during S phase. However, using purified cdk2 kinase and RP-A we are unable to detect a direct phosphorylation of RP-A by cdk2 kinase. This observation suggests that phosphorylation of DNA-bound RP-A at S phase is carried out by a kinase distinct from cdk2. Consistent with this we find that when single-stranded DNA is added to S phase extracts depleted of cdk2 kinase, RP-A is phosphorylated. Together these results suggest that cdk2 kinase participates in the activation of DNA replication at a stage prior to the binding of RP-A to the initiation complex. In addition to RP-A phosphorylation in S phase, we have also found that at the onset of mitosis RP-A is quantitatively phosphorylated and that phosphorylation is directly mediated by cdc2 kinase. However, at this time during the cell cycle, cdc2-dependent phosphorylation of RP-A is independent of DNA binding. These observations further demonstrate the distinctions between cdk2 and cdc2 kinases.

scholarly journals Diminished S-Phase Cyclin-Dependent Kinase Function Elicits Vital Rad53-Dependent Checkpoint Responses in Saccharomyces cerevisiae

2004 ◽  
Vol 24 (23) ◽  
pp. 10208-10222 ◽  
Author(s):  
Daniel G. Gibson ◽  
Jennifer G. Aparicio ◽  
Fangfang Hu ◽  
Oscar M. Aparicio
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Dna Replication ◽  
Replication Origin ◽  
S Phase ◽  
Replication Forks ◽  
Cyclin Dependent Kinase ◽  
Chromosomal Dna ◽  
Origin Firing ◽  
Late Origin

ABSTRACT Cyclin-dependent kinase (CDK) is required for the initiation of chromosomal DNA replication in eukaryotes. In Saccharomyces cerevisiae, the Clb5 and Clb6 cyclins activate Cdk1 and drive replication origin firing. Deletion of CLB5 reduces initiation of DNA synthesis from late-firing origins. We have examined whether checkpoints are activated by loss of Clb5 function and whether checkpoints are responsible for the DNA replication defects associated with loss of Clb5 function. We present evidence for activation of Rad53 and Ddc2 functions with characteristics suggesting the presence of DNA damage. Deficient late origin firing in clb5Δ cells is not due to checkpoint regulation, but instead, directly reflects the decreased abundance of S-phase CDK, as Clb6 activates late origins when its dosage is increased. Moreover, the viability of clb5Δ cells depends on Rad53. Activation of Rad53 by either Mrc1 or Rad9 contributes to the survival of clb5Δ cells, suggesting that both DNA replication and damage pathways are responsive to the decreased origin usage. These results suggest that reduced origin usage leads to stress or DNA damage at replication forks, necessitating the function of Rad53 in fork stabilization. Consistent with the notion that decreased S-CDK function creates stress at replication forks, deletion of RRM3 helicase, which facilitates replisome progression, greatly diminished the growth of clb5Δ cells. Together, our findings indicate that deregulation of S-CDK function has the potential to exacerbate genomic instability by reducing replication origin usage.

scholarly journals Schizosacchromyces pombeDpb2 Binds to Origin DNA Early in S Phase and Is Required for Chromosomal DNA Replication

2003 ◽  
Vol 14 (8) ◽  
pp. 3427-3436 ◽  
Author(s):  
Wenyi Feng ◽  
Luis Rodriguez-Menocal ◽  
Gökhan Tolun ◽  
Gennaro D'Urso
Keyword(s):  
Dna Replication ◽  
S Phase ◽  
Replication Initiation ◽  
Temperature Sensitive ◽  
The Novel ◽  
Chromosomal Dna ◽  
Dna Polymerase Epsilon ◽  
Dna Replication Initiation ◽  
Cycle Arrest ◽  
C Terminus

Genetic evidence suggests that DNA polymerase epsilon (Pol ϵ) has a noncatalytic essential role during the early stages of DNA replication initiation. Herein, we report the cloning and characterization of the second largest subunit of Pol ϵ in fission yeast, called Dpb2. We demonstrate that Dpb2 is essential for cell viability and that a temperature-sensitive mutant of dpb2 arrests with a 1C DNA content, suggesting that Dpb2 is required for initiation of DNA replication. Using a chromatin immunoprecipitation assay, we show that Dpb2, binds preferentially to origin DNA at the beginning of S phase. We also show that the C terminus of Pol ϵ associates with origin DNA at the same time as Dpb2. We conclude that Dpb2 is an essential protein required for an early step in DNA replication. We propose that the primary function of Dpb2 is to facilitate assembly of the replicative complex at the start of S phase. These conclusions are based on the novel cell cycle arrest phenotype of the dpb2 mutant, on the previously uncharacterized binding of Dpb2 to replication origins, and on the observation that the essential function of Pol ϵ is not dependent on its DNA synthesis activity.

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