DNA replication and repair of Tilapia cells. II. Effects of temperature on DNA replication and ultraviolet repair in Tilapia ovary cells

1988 ◽  
Vol 89 (2) ◽  
pp. 263-272
Author(s):  
J.D. Chen ◽  
F.H. Yew
Keyword(s):  
Molecular Weight ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Mammalian Cells ◽  
Excision Repair ◽  
Control Level ◽  
High Molecular Weight Dna ◽  
Wide Range ◽  
Effects Of Temperature ◽  
Fish Cells

TO-2 is a fish cell line derived from the Tilapia ovary. It grows over a wide range of temperature (15–34 degrees C). While most fish cells lack DNA excision repair and are hypersensitive to ultraviolet light (u.v.), Tilapia cells are more u.v.-resistant than mammalian cells. In this paper we report the effects of temperature on DNA replication and u.v. repair in TO-2 cells. When the cells were moved from 31 degrees C to the sublethal high temperature of 37 degrees C, the rate of DNA synthesis first decreased to 60%, then speedy recovery soon set in, and after 8 h at 37 degrees C the rate of DNA synthesis overshot the 31 degrees C control level by 180%. When moved to low temperature (18 degrees C) Tilapia cells also showed an initial suppression of DNA synthesis before settling at 30% of the control level. u.v. reduced but could not block DNA synthesis completely. The inhibition was overcome in 3 h at 37, 31 and 25 degrees C, but not at 18 degrees C. Initiation of nascent DNA synthesis was blocked at 4 J m-2 in TO-2 cells compared with less than or equal to 1 J m-2 in mammalian cells. After 9 J m-2 u.v. irradiation, low molecular weight DNA replication intermediates started to accumulate, and they could be chased into high molecular weight DNA with little delay. TO-2 cells showed low levels of u.v.-induced excision repair; but this was prominent compared with other fish cells. The u.v.-induced incision rate has been measured at various temperatures, and the activation energy of incision estimated to be 13 kcal mol-1 (1 cal approximately equal to 4.184 J).

scholarly journals Detection of base analogs incorporated during DNA replication by nanopore sequencing

2020 ◽  
Vol 48 (15) ◽  
pp. e88-e88 ◽  
Author(s):  
Daniela Georgieva ◽  
Qian Liu ◽  
Kai Wang ◽  
Dieter Egli
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Mammalian Cells ◽  
Single Dna Molecules ◽  
Synthetic Dna ◽  
Oxford Nanopore ◽  
Wide Range ◽  
Dna Strands ◽  
Single Method ◽  
Thymidine Analogs

Abstract DNA synthesis is a fundamental requirement for cell proliferation and DNA repair, but no single method can identify the location, direction and speed of replication forks with high resolution. Mammalian cells have the ability to incorporate thymidine analogs along with the natural A, T, G and C bases during DNA synthesis, which allows for labeling of replicating or repaired DNA. Here, we demonstrate the use of the Oxford Nanopore Technologies MinION to detect 11 different thymidine analogs including CldU, BrdU, IdU as well as EdU alone or coupled to Biotin and other bulky adducts in synthetic DNA templates. We also show that the large adduct Biotin can be distinguished from the smaller analog IdU, which opens the possibility of using analog combinations to identify the location and direction of DNA synthesis. Furthermore, we detect IdU label on single DNA molecules in the genome of mouse pluripotent stem cells and using CRISPR/Cas9-mediated enrichment, determine replication rates using newly synthesized DNA strands in human mitochondrial DNA. We conclude that this novel method, termed Replipore sequencing, has the potential for on target examination of DNA replication in a wide range of biological contexts.

scholarly journals Nonperiodic Activity of the Human Anaphase-Promoting Complex–Cdh1 Ubiquitin Ligase Results in Continuous DNA Synthesis Uncoupled from Mitosis

2000 ◽  
Vol 20 (20) ◽  
pp. 7613-7623 ◽  
Author(s):  
Claus Storgaard Sørensen ◽  
Claudia Lukas ◽  
Edgar R. Kramer ◽  
Jan-Michael Peters ◽  
Jiri Bartek ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Kinase Inhibitor ◽  
Cyclin B1 ◽  
S Phase ◽  
Anaphase Promoting Complex

ABSTRACT Ubiquitin-proteasome-mediated destruction of rate-limiting proteins is required for timely progression through the main cell cycle transitions. The anaphase-promoting complex (APC), periodically activated by the Cdh1 subunit, represents one of the major cellular ubiquitin ligases which, in Saccharomyces cerevisiae andDrosophila spp., triggers exit from mitosis and during G1 prevents unscheduled DNA replication. In this study we investigated the importance of periodic oscillation of the APC-Cdh1 activity for the cell cycle progression in human cells. We show that conditional interference with the APC-Cdh1 dissociation at the G1/S transition resulted in an inability to accumulate a surprisingly broad range of critical mitotic regulators including cyclin B1, cyclin A, Plk1, Pds1, mitosin (CENP-F), Aim1, and Cdc20. Unexpectedly, although constitutively assembled APC-Cdh1 also delayed G1/S transition and lowered the rate of DNA synthesis during S phase, some of the activities essential for DNA replication became markedly amplified, mainly due to a progressive increase of E2F-dependent cyclin E transcription and a rapid turnover of the p27Kip1 cyclin-dependent kinase inhibitor. Consequently, failure to inactivate APC-Cdh1 beyond the G1/S transition not only inhibited productive cell division but also supported slow but uninterrupted DNA replication, precluding S-phase exit and causing massive overreplication of the genome. Our data suggest that timely oscillation of the APC-Cdh1 ubiquitin ligase activity represents an essential step in coordinating DNA replication with cell division and that failure of mechanisms regulating association of APC with the Cdh1 activating subunit can undermine genomic stability in mammalian cells.

scholarly journals DNA Replication but Not Nucleotide Excision Repair Is Required for UVC-Induced Replication Protein A Phosphorylation in Mammalian Cells

2000 ◽  
Vol 20 (8) ◽  
pp. 2696-2705 ◽  
Author(s):  
Gregory Rodrigo ◽  
Sophie Roumagnac ◽  
Marc S. Wold ◽  
Bernard Salles ◽  
Patrick Calsou
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Nucleotide Excision Repair ◽  
Mammalian Cells ◽  
Excision Repair ◽  
Protein A ◽  
Replication Protein A ◽  
Replication Protein ◽  
Dependent Manner ◽  
Nucleotide Excision

ABSTRACT Exposure of mammalian cells to short-wavelength light (UVC) triggers a global response which can either counteract the deleterious effect of DNA damage by enabling DNA repair or lead to apoptosis. Several stress-activated protein kinases participate in this response, making phosphorylation a strong candidate for being involved in regulating the cellular damage response. One factor that is phosphorylated in a UVC-dependent manner is the 32-kDa subunit of the single-stranded DNA-binding replication protein A (RPA32). RPA is required for major cellular processes like DNA replication, and removal of DNA damage by nucleotide excision repair (NER). In this study we examined the signal which triggers RPA32 hyperphosphorylation following UVC irradiation in human cells. Hyperphosphorylation of RPA was observed in cells from patients with either NER or transcription-coupled repair (TCR) deficiency (A, C, and G complementation groups of xeroderma pigmentosum and A and B groups of Cockayne syndrome, respectively). This exclude both NER intermediates and TCR as essential signals for RPA hyperphosphorylation. However, we have observed that UV-sensitive cells deficient in NER and TCR require lower doses of UV irradiation to induce RPA32 hyperphosphorylation than normal cells, indicating that persistent unrepaired lesions contribute to RPA phosphorylation. Finally, the results of UVC irradiation experiments on nonreplicating cells and S-phase-synchronized cells emphasize a major role for DNA replication arrest in the presence of UVC lesions in RPA UVC-induced hyperphosphorylation in mammalian cells.

Association of c-myc protein with enzymes of DNA replication in high molecular weight fractions from mammalian cells

1991 ◽  
Vol 147 (3) ◽  
pp. 412-419 ◽  
Author(s):  
George P. Studzinski ◽  
Uma T. Shankavaram ◽  
Dorothy C. Moore ◽  
Prem Veer Reddy
Keyword(s):  
Molecular Weight ◽  
Dna Replication ◽  
High Molecular Weight ◽  
Mammalian Cells ◽  
Molecular Weight Fractions

A human nuclear protein with sequence homology to a family of early S phase proteins is required for entry into S phase and for cell division

1994 ◽  
Vol 107 (1) ◽  
pp. 253-265 ◽  
Author(s):  
I.T. Todorov ◽  
R. Pepperkok ◽  
R.N. Philipova ◽  
S.E. Kearsey ◽  
W. Ansorge ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Amino Acid ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Mammalian Cells ◽  
Nuclear Protein ◽  
Amino Acid Level ◽  
S Phase ◽  
Significant Similarity

Molecular cloning and characterisation of a human nuclear protein designated BM28 is reported. On the amino acid level this 892 amino acid protein, migrating on SDS-gels as a 125 kDa polypeptide, shares areas of significant similarity with a recently defined family of early S phase proteins. The members of this family, the Saccharomyces cerevisiae Mcm2p, Mcm3p, Cdc46p/Mcm5p, the Schizosaccharomyces pombe Cdc21p and the mouse protein P1 are considered to be involved in the onset of DNA replication. The highest similarity was found with Mcm2p (42% identity over the whole length and higher than 75% over a conservative region of 215 amino acid residues), suggesting that BM28 could represent the human homologue of the S. cerevisiae MCM2. Using antibodies raised against the recombinant BM28 the corresponding antigen was found to be localised in the nuclei of various mammalian cells. Microinjection of anti-BM28 antibody into synchronised mouse NIH3T3 or human HeLa cells presents evidence for the involvement of the protein in cell cycle progression. When injected in G1 phase the anti-BM28 antibody inhibits the onset of subsequent DNA synthesis as tested by the incorporation of bromodeoxyuridine. Microinjection during the S phase had no effect on DNA synthesis, but inhibits cell division. The data suggest that the nuclear protein BM28 is required for two events of the cell cycle, for the onset of DNA replication and for cell division.

scholarly journals Genetic Confirmation that the H5 Protein Is Required for Vaccinia Virus DNA Replication

2015 ◽  
Vol 89 (12) ◽  
pp. 6312-6327 ◽  
Author(s):  
Kathleen A. Boyle ◽  
Matthew D. Greseth ◽  
Paula Traktman
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Cell Line ◽  
Mammalian Cells ◽  
Indirect Evidence ◽  
Chemical Mutagenesis ◽  
Temperature Sensitive ◽  
Genome Replication ◽  
Content Type ◽  
Physical Autonomy

ABSTRACTThe duplication of the poxvirus double-stranded DNA genome occurs in cytoplasmic membrane-delimited factories. This physical autonomy from the host nucleus suggests that poxvirus genomes encode the full repertoire of proteins committed for genome replication. Biochemical and genetic analyses have confirmed that six viral proteins are required for efficient DNA synthesis; indirect evidence has suggested that the multifunctional H5 protein may also have a role. Here we show that H5 localizes to replication factories, as visualized by immunofluorescence and immunoelectron microscopy, and can be retrieved upon purification of the viral polymerase holoenzyme complex. The temperature-sensitive (ts) mutant Dts57, which was generated by chemical mutagenesis and has a lesion in H5, exhibits defects in DNA replication and morphogenesis under nonpermissive conditions, depending upon the experimental protocol. The H5 variant encoded by the genome of this mutant istsfor function but not stability. For a more precise investigation of how H5 contributes to DNA synthesis, we placed thets57 H5 allele in an otherwise wild-type viral background and also performed small interfering RNA-mediated depletion of H5. Finally, we generated a complementing cell line, CV-1–H5, which allowed us to generate a viral recombinant in which the H5 open reading frame was deleted and replaced with mCherry (vΔH5). Analysis of vΔH5 allowed us to demonstrate conclusively that viral DNA replication is abrogated in the absence of H5. The loss of H5 does not compromise the accumulation of other early viral replication proteins or the uncoating of the virion core, suggesting that H5 plays a direct and essential role in facilitating DNA synthesis.IMPORTANCEVariola virus, the causative agent of smallpox, is the most notorious member of thePoxviridaefamily. Poxviruses are unique among DNA viruses that infect mammalian cells, in that their replication is restricted to the cytoplasm of the cell. This physical autonomy from the nucleus has both cell biological and genetic ramifications. Poxviruses must establish cytoplasmic niches that support replication, and the genomes must encode the repertoire of proteins necessary for genome synthesis. Here we focus on H5, a multifunctional and abundant viral protein. We confirm that H5 associates with the DNA polymerase holoenzyme and localizes to the sites of DNA synthesis. By generating an H5-expressing cell line, we were able to isolate a deletion virus that lacks the H5 gene and show definitively that genome synthesis does not occur in the absence of H5. These data support the hypothesis that H5 is a crucial participant in cytoplasmic poxvirus genome replication.

scholarly journals Introduction and recovery of a selectable bacterial gene from the genome of mammalian cells

1982 ◽  
Vol 2 (8) ◽  
pp. 966-976
Author(s):  
M L Breitman ◽  
L C Tsui ◽  
M Buchwald ◽  
L Siminovitch
Keyword(s):  
Molecular Weight ◽  
Cell Line ◽  
Cell Lines ◽  
Mammalian Cells ◽  
Dna Molecules ◽  
High Molecular Weight Dna ◽  
Bacterial Gene ◽  
E Coli ◽  
Transformed Cell ◽  
Transformed Cell Lines

The simian virus 40 (SV40)-pBR322 recombinant, pSV2, carrying the origin of SV40 replication and the gpt gene of Escherichia coli, has been stably introduced into Chinese hamster ovary hprt- cells. All gpt-transformed cell lines were found to contain one or more insertions of pSV2 sequences exclusively associated with high-molecular-weight DNA. Additional analyses showed that at least one integrated copy in each cell line retained an intact gpt gene and flanking SV40 sequences required for expression of xanthine-guanine phosphoribosyltransferase. Most cell lines contained pSV2 sequences which had integrated with partial sequence duplication. Upon fusion with COS-1 cells, a simian cell line permissive for autonomous pSV2 replication, most gpt-transformed cell lines produced low-molecular-weight DNA molecules related to pSV2. The majority of these replicating DNAs were indistinguishable from the original transfecting plasmid in both size and restriction enzyme cleavage pattern. In addition, the recovered DNA molecules were able to confer ampicillin resistance to E. coli and to transform mouse L cells and Gpt- E. coli to a Gpt+ phenotype. These studies indicate that all of the genetic information carried by this SV40-plasmid recombinant can be introduced into and retrieved from the genome of mammalian cells.

A survey of DNA repair incision activities after ultraviolet irradiation of a range of human, hamster, and hamster-human hybrid cell lines

1982 ◽  
Vol 56 (1) ◽  
pp. 423-440
Author(s):  
A. Collins ◽  
C. Jones ◽  
C. Waldren
Keyword(s):  
Cell Lines ◽  
Ultraviolet Irradiation ◽  
Mammalian Cells ◽  
Excision Repair ◽  
Hybrid Cell ◽  
Standard Procedure ◽  
Repair Capacity ◽  
S1 Nuclease ◽  
Dna Damage And Repair ◽  
Wide Range

We describe a rapid and simple assay for DNA damage and repair in mammalian cells, based on the partial unwinding of nicked DNA in alkali, and involving transfer of this DNA to nitrocellulose and the digestion of single-stranded DNA with S1 nuclease, all steps taking place on tissue-culture chamber slides. Direct breakage of DNA by ionizing radiation has been examined, and we have developed a standard procedure for measuring enzymic breakage of DNA as an index of excision-repair capacity following ultraviolet irradiation. We report a wide range of repair capacities among various hamster and human cell lines, with considerable overlap between the two species. Hybrids between hamster and human cells tend to display repair activity characteristic of the hamster parent.

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