scholarly journals CHROMATIN STRUCTURE AND THE CELL DIVISION CYCLE

1972 ◽  
Vol 55 (2) ◽  
pp. 322-327 ◽  
Author(s):  
Thoru Pederson ◽  
Elliott Robbins
Keyword(s):  
Nuclear Dna ◽  
Binding Capacity ◽  
Nuclear Dna Content ◽  
Living Cells ◽  
S Phase ◽  
Minimal Level ◽  
Binding Profile ◽  
Chromosomal Proteins ◽  
Isolated Nuclei ◽  
Degree Of Association

Measurements of actinomycin-3H binding in synchronized HeLa cells reveal that the binding capacity of chromatin decreases progressively during the S phase despite a doubling of nuclear DNA content, reaches a minimal level during G2 and mitosis, and then increases gradually throughout the subsequent G1 interval. Since this pattern was evident in experiments with living cells, ethanol-fixed cells, and isolated nuclei, but not with purified DNA, the actinomycin binding profile may reflect changes in the degree of association between DNA and chromosomal proteins at different stages of the cell cycle.

scholarly journals The Complex Cell Cycle of the Dinoflagellate Protoctist Crypthecodinium Cohnii as Studied In Vivo and by Cytofluorimetry

1991 ◽  
Vol 100 (3) ◽  
pp. 675-682 ◽  
Author(s):  
YVONNE BHAUD ◽  
JEAN-MARIE SALMON ◽  
MARIE-ODILE SOYER-GOBILLARD
Keyword(s):  
Cell Cycle ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
S Phase ◽  
Vegetative Cells ◽  
Crypthecodinium Cohnii ◽  
Daughter Cells ◽  
The Times

The complete cell cycle of the dinoflagellate Crypthecodinium cohnii Biecheler 1938 was observed in vivo in a synchronized heterogeneous population, after DAPI staining of DNA. In a given population, the relative nuclear DNA content in each class of cell was measured using a new numerical image-analysis method that takes into account the total fluorescence intensity (FI), area (A) and shape factor (SF). The visible degree of synchronization of the population was determined from the number of cells with a nuclear content of 1C DNA at ‘synchronization’, time 0. One method of synchronization (method 1), based on the adhesiveness of the cysts, gave no better than 50% synchronization of the population; method 2, based on swimming cells released from cysts cultured on solid medium, gave 73% of cells with the same nuclear DNA content. A scatter plot of data for FI versus A in the first few hours after time 0 showed that the actual degree of synchronization of the population was lower. The length of the C. cohnii cell cycle determined in vivo by light microscopy was 10, 16 or 24 h for vegetative cells giving two, four or eight daughter cells, respectively. Histograms based on the FI measurements showed that in an initially synchronized population observed for 20 h, the times for the first cell cycle were: G1 phase, 6 h; S phase, 1 h 30 min; G2+M, 1h 30 min, with the release of vegetative cells occurring 1 or 2h after the end of cytokinesis. The times for the second cell cycle were G1+S, 3h; G2+M, 2h. FI and A taken together, suggested that the S phase is clearly restricted, as in higher eukaryotes. A and SF, taken together, showed that the large nuclear areas were always in cysts with two or four daughter cells. FI and SF, taken together, showed that the second S phase always occurred after completion of the first nuclear division. Our data concerning the course of the cell cycle in C. cohnii are compared with those from earlier studies, and the control of the number of daughter cells is discussed; this does not depend on the ploidy of the mother cell.

Temporal order of gene replication in Chinese hamster ovary cells

1989 ◽  
Vol 9 (7) ◽  
pp. 2881-2889
Author(s):  
J Taljanidisz ◽  
J Popowski ◽  
N Sarkar
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
Chinese Hamster Ovary Cells ◽  
Repetitive Sequences ◽  
Chinese Hamster ◽  
Nuclear Dna Content ◽  
Single Copy ◽  
S Phase ◽  
Specific Gene ◽  
Cell Permeabilization

To investigate the molecular basis of the regulatory mechanisms responsible for the orderly replication of the mammalian genome, we have developed an experimental system by which the replication order of various genes can be defined with relative ease and precision. Exponentially growing CHO-K1 cells were separated into populations representing various stages of the cell cycle by centrifugal elutriation and analyzed for cell cycle status flow cytometry. The replication of specific genes in each elutriated fraction was measured by labeling with 5-mercuri-dCTP and [3H]dTPP under conditions of optimal DNA synthesis after cell permeabilization with lysolecithin. Newly synthesized mercurated DNA from each elutriated fraction was purified by affinity chromatography on thiol-agarose and replicated with the large fragment of Escherichia coli DNA polymerase I by using [alpha-32P]dATP and random primers. The 32P-labeled DNA representative of various stages of the cell cycle was then hybridized with dot blots of plasmid DNA containing specific cloned genes. From these results, it was possible to deduce the nuclear DNA content at the time each specific gene replicated during S phase (C value). The C values of 29 genes, which included single-copy genes, multifamily genes, oncogenes, and repetitive sequences, were determined and found to be distributed over the entire S phase. Of the 28 genes studied, 19 had been examined by others using in vivo labeling techniques, with results which agreed with the replication pattern observed in this study. The replication times of nine other genes are described here for the first time. Our method of analysis is sensitive enough to determine the replication time of single-copy genes. The replication times of various genes and their levels of expression in exponentially growing CHO cells were compared. Although there was a general correlation between transcriptional activity and replication in the first half of S phase, examination of specific genes revealed a number of exceptions. Approximately 25% of total poly(A) RNA was transcribed from the late-replicating DNA.

Nuclear DNA content and chromosome numbers throughout the life cycle of the Colonia strain of the myxomycete, Physarum polycephalum

1977 ◽  
Vol 24 (1) ◽  
pp. 95-108
Author(s):  
J. Mohberg
Keyword(s):  
Lactic Acid ◽  
Life Cycle ◽  
Chromosome Number ◽  
Dna Content ◽  
Physarum Polycephalum ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
S Phase ◽  
Dna Analyses

Nuclear DNA content and ploidy have been determined at different stages of the life cycle of the Colonia strain of the myxomycete Physarum polycephalum. Analyses at the plasmodial stage showed that (a) Burton and Fuelgen DNA analyses agreed within 15% with strains which ranged from 0-6 to 3-6 pg of DNA per nucleus; (b) S-phase in Colonia is during the early part of interphase as in the Wisconsin strain; (c) in heterothallic and heterothallic × Colonia crossed strains there are 1-0-1-2 pg of DNA and 70 chromosomes per nucleus and in Colonia 0-6 pg of DNA and 40 chromosomes. Germinating spores of all strains contained one population of cells with about 0-5 pg of DNA and 40 chromosomes and another of larger cells with up to 2-5 pg of DNA and 200 chromosomes. The polyploid nuclei comprised 2–20% of the total in heterothallic strains, 2–65% in heterothallic × Colonia crosses and 25–75% in Colonia. A method was devised for making chromosome spreads of amoebae grown on bacterial lawns. Cells were first exposed to dilute formaldehyde at 26 degrees C for 30 min, then spread on slides with hot lactic acid and strained. Such spreads of CLd (Colonia) and RSD4 (heterothallic) amoebae both contained about 40 chromosomes. The data are consistent with the view that Colonia is haploid throughout its life cycle and that chromosome number is neither halved during sporulation nor doubled during plasmoidal formation. However, the possibility exists that an alternance of ploidy occurs by way of the few diploid nuclei present in the plasmodium.

NUCLEIC ACID-REACTIVE ANTIBODIES SPECIFIC FOR NUCLEOSIDES AND NUCLEOTIDES

1972 ◽  
Vol 71 (2_Suppla) ◽  
pp. S206-S221 ◽  
Author(s):  
B. F. Erlanger ◽  
D. Senitzer ◽  
O. J. Miller ◽  
S. M. Beiser
Keyword(s):  
Nuclear Dna ◽  
Chinese Hamster ◽  
Living Cells ◽  
S Phase ◽  
Lung Cells ◽  
Small Areas ◽  
Pyrimidine Nucleosides ◽  
Naturally Occurring ◽  
Biochemical Systems ◽  
Human And Mouse

ABSTRACT A method is described for making anti-purine and anti-pyrimidine anti-bodies by immunization with conjugates of naturally-occurring nucleosides or nucleotides with carrier proteins. The specificities of the antisera are presented and shown to be predominantly, if not solely, for the determinant purine or pyrimidine group presented in the antigen. The antisera react with single-stranded or denatured DNA and, in the case of anti-adenosine, with RNA preparations. The antisera have been utilized in biochemical systems to inhibit the priming ability of DNA in a DNA-dependent DNA polymerase system, to detect minor bases such as 6-methyladenosine in DNA, and to detect small areas of single-strandedness in otherwise native DNA. The sera have also been shown to react with living cells, inhibiting the development of fertilized sea urchin eggs and entering and inhibiting transformed Chinese hamster lung cells without affecting normal ones. They have been used in immunofluorescence experiments in which they have been shown to react with nuclear DNA of fixed mouse L-cells harvested during the S phase. Moreover, they have found application in the characterization and identification of human and mouse chromosomes. Finally, initial studies have shown that they can be used in highly specific radioimmunoassays for purine and pyrimidine nucleosides.

scholarly journals Temporal order of gene replication in Chinese hamster ovary cells.

1989 ◽  
Vol 9 (7) ◽  
pp. 2881-2889 ◽  
Author(s):  
J Taljanidisz ◽  
J Popowski ◽  
N Sarkar
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
Chinese Hamster Ovary Cells ◽  
Repetitive Sequences ◽  
Chinese Hamster ◽  
Nuclear Dna Content ◽  
Single Copy ◽  
S Phase ◽  
Specific Gene ◽  
Cell Permeabilization

To investigate the molecular basis of the regulatory mechanisms responsible for the orderly replication of the mammalian genome, we have developed an experimental system by which the replication order of various genes can be defined with relative ease and precision. Exponentially growing CHO-K1 cells were separated into populations representing various stages of the cell cycle by centrifugal elutriation and analyzed for cell cycle status flow cytometry. The replication of specific genes in each elutriated fraction was measured by labeling with 5-mercuri-dCTP and [3H]dTPP under conditions of optimal DNA synthesis after cell permeabilization with lysolecithin. Newly synthesized mercurated DNA from each elutriated fraction was purified by affinity chromatography on thiol-agarose and replicated with the large fragment of Escherichia coli DNA polymerase I by using [alpha-32P]dATP and random primers. The 32P-labeled DNA representative of various stages of the cell cycle was then hybridized with dot blots of plasmid DNA containing specific cloned genes. From these results, it was possible to deduce the nuclear DNA content at the time each specific gene replicated during S phase (C value). The C values of 29 genes, which included single-copy genes, multifamily genes, oncogenes, and repetitive sequences, were determined and found to be distributed over the entire S phase. Of the 28 genes studied, 19 had been examined by others using in vivo labeling techniques, with results which agreed with the replication pattern observed in this study. The replication times of nine other genes are described here for the first time. Our method of analysis is sensitive enough to determine the replication time of single-copy genes. The replication times of various genes and their levels of expression in exponentially growing CHO cells were compared. Although there was a general correlation between transcriptional activity and replication in the first half of S phase, examination of specific genes revealed a number of exceptions. Approximately 25% of total poly(A) RNA was transcribed from the late-replicating DNA.

scholarly journals Relationship between nuclear DNA-content of sperm cells and the timing of events in the cell cycle of Brassica campestris L. (Brassicaceae)

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Hua Deng
Keyword(s):  
Cell Cycle ◽  
Quantitative Analysis ◽  
Dna Content ◽  
Nuclear Dna ◽  
Brassica Campestris ◽  
Nuclear Dna Content ◽  
Pollen Grain ◽  
S Phase ◽  
Sperm Cells ◽  
Generative Cells

In this work we conducted a quantitative analysis of the nuclear DNA-content of developing sperm cells of the plant <em>Brassica campestris</em> L. The sperm cells were in young pollen grain, mature pollen grain and pollen tubes. When generative cells, at the pre-anthesis stage, split into two sperm cells, we have established that the newly-formed sperm cells begin to synthesize nuclear DNA in developing pollen grain of <em>B. campestris</em>. We measured this DNA-content during the development of sperm cells. The results indicate that during development, sperm cells of <em>B. campestris</em> have passed the G<sub>1</sub> phase of the cell cycle and entered the S phase, presumably then fusing with egg cells at a level of 2C, as is characteristic of G<sub>2</sub> type fertilization in angiosperms.

Impact d'un traitement par le cycloheximide sur la reprise du cycle et sur les teneurs en protéines du bourgeon cotylédonaire du Pois réactivé par décapitation

1990 ◽  
Vol 68 (2) ◽  
pp. 420-427 ◽  
Author(s):  
Arlette Nougarède ◽  
Pierre Rondet ◽  
Pierre Landré ◽  
Robert Saint-Côme
Keyword(s):  
Protein Content ◽  
Mitotic Activity ◽  
Dna Content ◽  
Nuclear Protein ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
S Phase ◽  
Cytoplasmic Protein ◽  
The Mean ◽  
Low Amplitude

Following ablation of the main stem (decapitation), the mean nuclear protein content of the Pisum cotyledonary bud apical cells increased 35% as early as the 6th hour, just when a massive entry into the S phase was registered, and reached a maximum, with a 157% increase, at the 39th hour, when the mitotic activity was also at its highest. The ratio nuclear protein/nuclear DNA content was then multiplied by 1.8 in comparison with the ratio observed in the G0–1 noncycling nuclei of the inhibited cotyledonary bud. In the bud treated with cycloheximide, the mean nuclear protein content slowly increased following decapitation, but remained greatly inferior to that of the controls. A slight entry into the S phase was noticed at the 24th hour and the mean nuclear protein content, then maximal, increased 32% in comparison with the inhibited buds. In the control buds, the mean protoplasmic proteins content increased 116% at the 39th hour (maximal value), whereas it increased only 25% in the treated buds. Following treatment with cycloheximide, the entry into the S phase was postponed and of low amplitude. However, the recycling nuclei were able to divide. An increase in the mean nuclear and cytoplasmic protein content was a prerequisite if the entry into the S phase of G0–1, nuclei was not to be postponed.

scholarly journals Pattern of DNA increase in macronuclear anlagen of Tetrahymena

1986 ◽  
Vol 83 (1) ◽  
pp. 155-164
Author(s):  
J. Roth ◽  
G. Cleffmann
Keyword(s):  
Cell Cycle ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
S Phase ◽  
The Mean

By combining cytophotometry with autoradiography, five stages of macronuclear anlagen can be discriminated by their DNA content until the end of the first cell cycle after conjugation in Tetrahymena. DNA increases from 2C to about 32C. Each S-phase is followed by a non-synthetic period. Comparing the mean nuclear DNA content after and before each S-phase revealed that 16C anlagen contain significantly less DNA than twice the amount of 8C anlagen. This is unlike the situation in other S-phases during which the amount of DNA is precisely doubled. In the second cell cycle after conjugation some of the cells increase their macronuclear G2 DNA content beyond the 64C stage, while the majority show a mean G2 content of about 64C.

Prognostic value of nuclear DNA content in papillary and follicular thyroid cancer

1988 ◽  
Vol 12 (4) ◽  
pp. 503-507 ◽  
Author(s):  
Jaap F. Hamming ◽  
Lodewijk J. D. M. Schelfhout ◽  
Cees J. Cornelisse ◽  
Cornelis J. H. van de Velde ◽  
Bernard M. Goslings ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Dna Content ◽  
Prognostic Value ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Follicular Thyroid Cancer
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