CHANGES IN CELL PROLIFERATION RATE IN MOUSE UTERINE EPITHELIUM DURING CONTINUOUS OESTROGEN TREATMENT

1974 ◽  
Vol 61 (1) ◽  
pp. 117-121 ◽  
Author(s):  
AUDREY E. LEE ◽  
L. A. ROGERS ◽  
GAIL TRINDER
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Dna Synthesis ◽  
Mitotic Index ◽  
Cycle Time ◽  
Luminal Epithelium ◽  
Cell Cycle Time ◽  
Oestrogen Treatment ◽  
Probability Of Transition ◽  
The Mean

SUMMARY Fraction of labelled mitoses (FLM) curves were constructed for mouse uterine luminal epithelium during oestradiol treatment; on day 2 when mitosis was high, and on days 4 and 9 when mitosis was low. No difference was found between the duration of DNA synthesis on these 3 days. The distance between the first and second peaks, usually taken as an estimate of the mean cell cycle time, did not change significantly between days 2 and 4, although the labelling index fell from 38 to 8%. The second peaks of the FLM curves became progressively lower on the three days examined, which was consistent with the interpretation that there was a reduction in the probability of transition of cells from G1 (the post-mitotic period) into the replicative phase of the cell cycle, resulting in the observed fall in mitotic index.

Nuclear DNA content and minimum generation time in herbaceous plants

1972 ◽  
Vol 181 (1063) ◽  
pp. 109-135 ◽  
Keyword(s):  
Cell Cycle ◽  
Dna Content ◽  
Cycle Time ◽  
Generation Time ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Annual Species ◽  
Cell Cycle Time ◽  
Developmental Processes ◽  
The Mean

Many components of cell and nuclear size and mass are correlated with nuclear DNA content in plants, as also are the durations and rates of such developmental processes as mitosis and meiosis. It is suggested that the multiple effects of the mass of nuclear DNA which affect all cells and apply throughout the life of the plant can together determine the minimum generation time for each species. The durations of mitosis and of meiosis are both positively correlated with nuclear DNA content and, therefore, species with a short minimum generation time might be expected to have a shorter mean cell cycle time and mean meiotic duration, and a lower mean nuclear DNA content, than species with a long mean minimum generation time. In tests of this hypothesis, using data collated from the literature, it is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species. Furthermore, the mean nuclear DNA content of annual species is significantly lower than for perennial species both in dicotyledons and monocotyledons. Ephemeral species have a significantly lower mean nuclear DNA content than annual species. Among perennial monocotyledons the mean nuclear DNA content of species which can complete a life cycle within one year (facultative perennials) is significantly lower than the mean nuclear DNA content of those which cannot (obligate perennials). However, the mean nuclear DNA content of facultative perennials does not differ significantly from the mean for annual species. It is suggested that the effects of nuclear DNA content on the duration of developmental processes are most obvious during its determinant stages, and that the largest effects of nuclear DNA mass are expressed at times when development is slowest, for instance, during meiosis or at low temperature. It has been suggested that DNA influences development in two ways, directly through its informational content, and indirectly by the physical-mechanical effects of its mass. The term 'nucleotype' is used to describe those conditions of the nucleus which effect the phenotype independently of the informational content of the DNA. It is suggested that cell cycle time, meiotic duration, and minimum generation time are determined by the nucleotype. In addition, it may be that satellite DNA is significant in its nucleotypic effects on developmental processes.

DETERMINATION OF CELL CYCLE IN PLANTS USING BrdU-FPG

1980 ◽  
Vol 22 (2) ◽  
pp. 305-308 ◽  
Author(s):  
Kirby J. Evans ◽  
W. Gary Filion
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cycle Time ◽  
Differential Staining ◽  
Root Tip ◽  
Cell Cycle Time ◽  
Sister Chromatids ◽  
Vicia Faba L ◽  
Established Cell

The BrdU-FPG method for differential staining of sister chromatids was employed to estimate the cell cycle time in two plants species. The protocol is based upon the ability to differentiate cytologically between chromosomes which have completed two or three DNA synthesis phases. Vicia faba L. which has a well established cell cycle time was used to verify the technique. Utilizing this method the cell cycle time of Zebrina pendula Schnizl. root tip meristem cells was determined to be 17.0 hours.

THE EFFECTS OF OESTROGEN ON THE CELL CYCLE IN EPITHELIAL AND CONNECTIVE TISSUES OF THE MOUSE UTERUS

1972 ◽  
Vol 55 (1) ◽  
pp. 21-30 ◽  
Author(s):  
R. M. DAS
Keyword(s):  
Cell Cycle ◽  
Steady State ◽  
S Phase ◽  
Luminal Epithelium ◽  
Connective Tissues ◽  
Mouse Uterus ◽  
Oestrogen Treatment ◽  
Ovariectomized Mice ◽  
Generation Times ◽  
The Mean

SUMMARY The duration of stages of the cell cycle in the uterine epithelial and stromal tissues of ovariectomized mice was estimated by the labelled mitosis method. In untreated animals the mean duration of the S phase (DNA synthesis) was 10·5 h in the glandular and luminal epithelium. Oestrogen treatment shortened it to 6 h in both tissues. In the endometrial stroma of progesterone-treated mice the duration of S was 8 h; when oestrogen was given it increased slightly. The generation times estimated under steady-state conditions were 270,156 and 383 h respectively in the lumen, glands and stroma of untreated mice. After oestrogen stimulation the responses became highly synchronized.

scholarly journals Connexin 37 profoundly slows cell cycle progression in rat insulinoma cells

2008 ◽  
Vol 295 (5) ◽  
pp. C1103-C1112 ◽  
Author(s):  
Janis M. Burt ◽  
Tasha K. Nelson ◽  
Alexander M. Simon ◽  
Jennifer S. Fang
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cycle Time ◽  
Cell Cycle Progression ◽  
Serum Deprivation ◽  
Cell Cycle Time ◽  
Cycle Progression ◽  
Suppressive Function ◽  
Connexin 37 ◽  
Rat Insulinoma

In addition to providing a pathway for intercellular communication, the gap junction-forming proteins, connexins, can serve a growth-suppressive function that is both connexin and cell-type specific. To assess its potential growth-suppressive function, we stably introduced connexin 37 (Cx37) into connexin-deficient, tumorigenic rat insulinoma (Rin) cells under the control of an inducible promoter. Proliferation of these iRin37 cells, when induced to express Cx37, was profoundly slowed: cell cycle time increased from 2 to 9 days. Proliferation and cell cycle time of Rin cells expressing Cx40 or Cx43 did not differ from Cx-deficient Rin cells. Cx37 suppressed Rin cell proliferation irrespective of cell density at the time of induced expression and without causing apoptosis. All phases of the cell cycle were prolonged by Cx37 expression, and progression through the G1/S checkpoint was delayed, resulting in accumulation of cells at this point. Serum deprivation augmented the effect of Cx37 to accumulate cells in late G1. Cx43 expression also affected cell cycle progression of Rin cells, but its effects were opposite to Cx37, with decreases in G1 and increases in S-phase cells. These effects of Cx43 were also augmented by serum deprivation. Cx-deficient Rin cells were unaffected by serum deprivation. Our results indicate that Cx37 expression suppresses cell proliferation by significantly increasing cell cycle time by extending all phases of the cell cycle and accumulating cells at the G1/S checkpoint.

Comparison of Multiple Injections with Continuous Infusion of Tritiated Thymidine, and Estimation of the Cell Cycle Time

1969 ◽  
Vol 5 (3) ◽  
pp. 575-582
Author(s):  
W. K. BLENKINSOPP ◽  
C. W. GILBERT
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Continuous Infusion ◽  
Cycle Time ◽  
Squamous Epithelium ◽  
Tritiated Thymidine ◽  
Intraperitoneal Administration ◽  
Cell Cycle Time ◽  
Multiple Injections ◽  
Stratified Squamous Epithelium

Labelled nuclei were counted in stratified squamous epithelium in mice killed after 24 h intraperitoneal administration of tritiated thymidine to label cells synthesizing deoxyribonucleic acid. Multiple injections produced the same result as an infusion of tritiated thymidine given after 24 h infusion of saline, but infusion of tritiated thymidine alone produced a different result. Thus, cell proliferation was depressed during the first 24 h of continuous infusion but was normal during the second 24 h. Comparison of proliferation of the oesophageal epithelium at the level of the thyroid and at the level of the diaphragm showed no difference between the two. Comparison of male with female mice given 72-h infusions of tritiated thymidine showed that cell proliferation occurred at the same rate in both. The cell cycle time was estimated in the epithelium of the oesophagus and tongue by comparison of mice given a single injection with mice given multiple injections of tritiated thymidine.

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