Changes in the organization of chromosomes during the cell cycle: response to ultraviolet light

1975 ◽  
Vol 17 (3) ◽  
pp. 539-565
Author(s):  
S.L. Schor ◽  
R.T. Johnson ◽  
C.A. Waldren
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Ultraviolet Light ◽  
Hela Cells ◽  
Close Correlation ◽  
Chromosome Condensation ◽  
Unscheduled Dna Synthesis ◽  
Interphase Chromosome ◽  
Interphase Cells ◽  
Chromosome Decondensation

Fusion between mitotic and interphase cells results in the premature condensation of the interphase chromosomes into a morphology related to the position in the cell cycle at the time of fusion. These prematurely condensed chromosomes (PCC) have been used in conjunction with u.v. irradiation to examine the interphase chromosome condensation cycle of HeLa cells. The following observations have been made: (I) There is a progressive decondensation of the chromosomes during G1 which is accentuated by u.v. irradiation: (2) The chromosomes become more resistant to u.v.-induced decondensation during G2 and mitosis. (3) There is a close correlation between the degree of chromosome decondensation and the amount of unscheduled DNA synthesis induced by u.v. irradiation during G1 and mitosis: (4) Hydroxyurea enhances the ability of u.v. irradiation to promote the decondensation of chromosomes during G1, G2 and mitosis. Hydroxyurea also potentiates the lethal action of u.v. irradiation during mitosis and G1. These data are discussed in relation to the suggestion that chromosomes undergo a progressive decondensation during G1 and condensation during G2.

scholarly journals Lesions induced in DNA by ultraviolet light are repaired at the nuclear cage

1984 ◽  
Vol 70 (1) ◽  
pp. 189-196
Author(s):  
S.J. McCready ◽  
P.R. Cook
Keyword(s):  
Dna Synthesis ◽  
Ultraviolet Light ◽  
Hela Cells ◽  
Nuclear Matrix ◽  
Ultraviolet Irradiation ◽  
Mammalian Cells ◽  
Nuclear Dna ◽  
S Phase ◽  
Unscheduled Dna Synthesis ◽  
Phase Synthesis

In mammalian cells, S-phase DNA synthesis occurs at sites fixed to a sub-nuclear structure, the nuclear matrix or cage. This is an ordered network of non-histone proteins, which maintains its essential morphology even in the absence of DNA. We show here that unscheduled DNA synthesis following exposure of HeLa cells to ultraviolet light also takes place at this sub-structure. We also show that ultraviolet irradiation grossly reorganizes nuclear DNA, arresting S-phase synthesis at the cage and leaving the residual synthesis highly localized.

Effects of ultraviolet light on synchronized Chinese hamster ovary cells; potentiation by hydroxyurea

1977 ◽  
Vol 28 (1) ◽  
pp. 29-48
Author(s):  
K. Burg ◽  
A.R. Collins ◽  
R.T. Johnson
Keyword(s):  
Dna Synthesis ◽  
Ultraviolet Light ◽  
Hela Cells ◽  
Chinese Hamster Ovary ◽  
Ultraviolet Irradiation ◽  
Chromosome Structure ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Ovary Cells

We have examined the effects of hydroxyurea on u.v.-irradiated Chinese hamster CHO-KI cells. Ultraviolet irradiation followed by incubation with hydroxyurea causes only slight disruption of DNA and chromosome structure in CHO-KI cells compared with HeLa cells. There is, however, a clear potentiation by hydroxyurea of the u.v. killing of CHO-KI cells, which is most pronounced at those points in the cycle which are reported to have small DNA precursor pools. This potentiation is reduced when DNA precursors are provided together with hydroxyurea. These data are discussed in terms of an uncoupling of excision and repair DNA synthesis.

Replication and transcription sites are colocalized in human cells

1994 ◽  
Vol 107 (2) ◽  
pp. 425-434 ◽  
Author(s):  
A.B. Hassan ◽  
R.J. Errington ◽  
N.S. White ◽  
D.A. Jackson ◽  
P.R. Cook
Keyword(s):  
Cell Cycle ◽  
Confocal Microscopy ◽  
Dna Synthesis ◽  
Fluorescent Probes ◽  
Hela Cells ◽  
Nuclear Architecture ◽  
Human Cells ◽  
Dynamic Nature ◽  
Nucleotide Triphosphates ◽  
Transcription Sites

HeLa cells synchronized at different stages of the cell cycle were permeabilized and incubated with analogues of nucleotide triphosphates; then sites of incorporation were immunolabeled with the appropriate fluorescent probes. Confocal microscopy showed that sites of replication and transcription were not diffusely spread throughout nuclei, reflecting the distribution of euchromatin; rather, they were concentrated in ‘foci’ where many polymerases act together. Transcription foci aggregated as cells progressed towards the G1/S boundary; later they dispersed and became more diffuse. Replication was initiated only at transcription sites; later, when heterochromatin was replicated in enlarged foci, these remained sites of transcription. This illustrates the dynamic nature of nuclear architecture and suggests that transcription may be required for the initiation of DNA synthesis.

Dynamic changes of NuMA during the cell cycle and possible appearance of a truncated form of NuMA during apoptosis

1996 ◽  
Vol 109 (2) ◽  
pp. 277-288 ◽  
Author(s):  
H.L. Hsu ◽  
N.H. Yeh
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Structural Integrity ◽  
Chromatin Condensation ◽  
Tail Domain ◽  
Truncated Form ◽  
Cdc2 Kinase ◽  
Mitotic Apparatus ◽  
Interphase Cells ◽  
Late Stages

We have demonstrated that dynamic redistribution of nuclear-mitotic apparatus (NuMA) protein in the cell cycle is correlated temporally and spatially with its biochemical modifications. In interphase, NuMA behaves solely as a 220 kDa nuclear matrix-associated protein. After initiation of DNA condensation during mitosis, NuMA is phosphorylated by Cdc2 kinase into a 240 kDa form which is transported quickly to the centrosomal region. Once cells have passed the metaphase-anaphase transition, the 240 kDa form of NuMA either becomes a 180 kDa truncated form which is fated to be degraded completely before mitotic exit, or returns to the 220 kDa form that relocates to the daughter nuclei and remains throughout interphase. Apparently, a proteolytic enzyme is activated during the late stages of mitosis. After induction of a 180 kDa form of NuMA in interphase HeLa cells by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, nuclear apoptotic phenomena including chromatin condensation, DNA fragmentation, and micronucleation were observed. However, the same treatment did not induce apoptosis in mitotic phase-arrested HeLa cells. The 180 kDa form of NuMA was demonstrated to be a truncated product, at least lacking the tail domain. When HL60 cells were stimulated by diverse apoptosis inducers such as camptothecin, staurosporine, cycloheximide, and A23187, the extent of NuMA cleavage to produce a 180 kDa product was comparable with the degree of oligonucleosomal laddering. NuMA cleavage is likely to be a consequence of the onset of apoptosis. The intact 220 kDa NuMA functions in interphase cells to retain the nuclear structural integrity. Additionally, NuMA appears to act as a nuclear structural target for a death protease during apoptosis.

scholarly journals Induction of unscheduled DNA synthesis in hairless mouse epidermis by ultraviolet light.

2000 ◽  
Vol 25 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Masaaki MORI ◽  
Hiroshi KOBAYASHI ◽  
Masako NAGANUMA ◽  
Chiyomi SUGIYAMA ◽  
Yoshio KATSUMURA ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Ultraviolet Light ◽  
Hairless Mouse ◽  
Unscheduled Dna Synthesis ◽  
Mouse Epidermis

Comparative induction of unscheduled dna synthesis (uds) in hela cells by structurally related allylic compounds.

1983 ◽  
Vol 18 ◽  
pp. 120
Author(s):  
D. Schiffmann ◽  
E. Eder ◽  
T. Neudecker ◽  
D. Henschler
Keyword(s):  
Dna Synthesis ◽  
Hela Cells ◽  
Unscheduled Dna Synthesis
Sign in / Sign up

Export Citation Format

Share Document