The neural cell cycle in the looptail (Lp ) mutant mouse

Development ◽  
1974 ◽  
Vol 32 (3) ◽  
pp. 697-705
Author(s):  
Doris B. Wilson ◽  
E. M. Center
Keyword(s):  
Cell Cycle ◽  
Early Development ◽  
Generation Time ◽  
Mutant Mouse ◽  
Tritiated Thymidine ◽  
Neural Cell ◽  
Abnormal Development ◽  
Ventricular Cells ◽  
The Difference ◽  
Mitotic Figures

The cell cycle of mesencephalic ventricular cells was studied by means of tritiated thymidine radioautography during normal and abnormal development in the looptail (Lp ) mutant mouse. The total generation time, DNA-synthetic (S), premitotic (G2), mitotic (M), and postmitotic (G1) periods were compared in looptail homozygotes (Lp/Lp ) which exhibit neural dysraphism and in their normal littermates (+ / +) at 10 and 11 days ’ gestation. Both normal and abnormal embryos showed a chronological lengthening of the generation time between the 10th and 11th day. However, the generation time in the 10-day abnormal brains was 4·5 h longer than that in normal littermates, and the difference was the result of an increase mainly in the M and G1 periods. At 11 days of gestation the generation time in the abnormal brains increased by 50 h over that of the normal brains. Since the cell cycle was actually prolonged in the defective brains, the increased numbers of mitotic figures which characterize the looptail homozygote brain during early development appear to reflect the lengthening of the mitotic period rather than increased proliferation.

Cell cycle analysis of facial mesenchyme in the chick embryo

Development ◽  
1984 ◽  
Vol 81 (1) ◽  
pp. 49-59
Author(s):  
Robert Minkoff
Keyword(s):  
Cell Cycle ◽  
Chick Embryo ◽  
Generation Time ◽  
Growth Fraction ◽  
Computer Assisted ◽  
Pulse Labelling ◽  
Transit Times ◽  
Generation Times ◽  
The Difference ◽  
Slow Cycling

Cell cycle parameters were analysed in mesenchyme of the maxillary process and the roof of the stomodeum in the chick embryo from stages 19 through 28. The generation times at stages 24–26 were determined by pulse labelling of embryos with [3H]thymidine, followed by labelled mitosis counts and construction and analysis of percent-labelled mitosis curves employing computer-assisted curve-fitting techniques. The median generation time was approximately 10·6 h in the maxillary process, and 16 h in the roof of the stomodeum; corresponding values for mean generation times were approximately 12·0 and 18·2 h, respectively. Median values for transit times of G1, S, and G2 were 2·0, 5·4, and 2·5 h in the maxillary process and 5·2, 6·7, and 2·7 h in the roof of the stomodeum. The distribution of generation times of cells in the roof of the stomodeum, however, appeared to be more heterogeneous than those of cells in the maxillary process. The percentage of cells which continue to cycle rapidly (i.e. the ‘growth fraction’) was determined by repeated-labelling experiments with [3H]thymidine in chick embryos from stages 19 through 28. Cumulative labelling of mesenchymal cells in both the maxillary process and roof of the stomodeum approached 100 % at stage 19 but dropped markedly from stage 19 to 25 declining to approximately 60–70 % in the maxillary process, and to 30 % in the roof of the stomodeum. The decline in cell proliferation rates for these regions, determined in previous studies with labelling indices, appears to be a result of the removal of cells from rapidly cycling cell populations into subpopulations which are cycling more slowly and possibly into subpopulations which have become quiescent; the difference in growth rates between these regions could be attributed to the time of appearance and the size of these emerging slow cycling or quiescent subpopulations.

Size determination in Hydra: The roles of growth and budding

Development ◽  
1973 ◽  
Vol 30 (1) ◽  
pp. 1-19
Author(s):  
John W. Bisbee
Keyword(s):  
Tritiated Thymidine ◽  
Growth Dynamics ◽  
Distal Portion ◽  
Effect Of Temperature ◽  
Surface Areas ◽  
Two Temperatures ◽  
Size Of Animals ◽  
The Difference ◽  
Mitotic Figures ◽  
Bud Initiation

Hydra pseudoligactis cultured at 9 °C for 3–4 weeks are one-and-a-half times larger than those cultured at 18 °C. The size of Hydra is correlated with the numbers of epitheliomuscular and digestive cells in the distal portion of the animal and with the diameters of the epithelio-muscular cells in the peduncle. Counts of mitotic figures and tritiated-thymidine-labeled nuclei and determinations of increase in mass of Hydra populations suggest that the difference caused by these temperatures does not affect mitosis. At 9 °C buds are initiated at a lower rate and take longer to develop than at 18 °C. The surface-areas of buds raised at the two temperatures are similar. Because Hydra raised at the two temperatures have similar growth dynamics, the differences in sizes of the animals cannot be due to growth rate. The observed effect of temperature on bud initiation and development is probably relevant to the increased size of animals raised at 9 °C, since these larger animals may be accumulating more cells while losing fewer to buds.

The uptake of tritiated thymidine by human amnion cells: a correlation with cell structure

1968 ◽  
Vol 14 (7) ◽  
pp. 791-797
Author(s):  
S. B. Hrushovetz ◽  
J. C. Wilt ◽  
E. S. C. Lee
Keyword(s):  
Cell Cycle ◽  
Incubation Period ◽  
Cell Population ◽  
Hela Cells ◽  
Tritiated Thymidine ◽  
Cell Structure ◽  
Human Amnion ◽  
Proliferative Phase ◽  
Mitotic Figures ◽  
Continuous Labelling

It was found that less than 1% of amnion cells, either as membrane biopsies, as trypsinized cell suspensions, or grown as monolayers on glass incorporated tritiated thymidine during a 1-hour incubation period; this was in contrast to HeLa cells in which over 30% of the cell population incorporated tritiated thymidine. Continuous labelling with tritiated thymidine for a 24-hour period with or without colchicine failed to increase the percentage of labelled amnion cells, while a minimum of 80% of the HeLa cells became labelled. Less than 0.1% of the amnion cells were in mitosis, compared to 4% for HeLa cells. Incubation with colchicine for 24 hours failed to increase the percentage of mitotic figures of the amnion cells. It is concluded that most of the primary amnion cells are in the non-proliferative phase of the cell cycle.

scholarly journals SCHWANN CELL PROLIFERATION IN DEVELOPING MOUSE SCIATIC NERVE

1967 ◽  
Vol 34 (3) ◽  
pp. 735-743 ◽  
Author(s):  
A. K. Asbury
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Sciatic Nerve ◽  
Schwann Cell ◽  
Schwann Cells ◽  
Generation Time ◽  
Dividing Cells ◽  
Mitotic Figures ◽  
Relationship Of ◽  
The Relationship

Proliferation of Schwann cells in neonatal mouse sciatic nerve was studied radioautographically in 1-µ glycol methacrylate sections. 28 mice were injected with thymidine-3H, 4 µc/g, 48 hr after birth, and were killed serially over the next 4 days. For the cell cycle following injection, the generation time was approximately 24 hr as determined by grain-count halving data; the duration of synthesis phase was 8 hr as determined from a curve constructed from the per cent of mitotic figures containing label; and the labeling index was 9% at 2 hr after injection. With these estimates, the per cent of Schwann cells proliferating was calculated to be 27%. In addition, roughly 25% of dividing cells appeared to cease division during the cell cycle under study. The relationship of these findings to other events during maturation of nerve is discussed.

The Synthesis and Migration of Nuclear Proteins during Mitosis and differentiation of Cells in Rats

1965 ◽  
Vol s3-106 (75) ◽  
pp. 229-240
Author(s):  
R. T. SIMS
Keyword(s):  
Granular Cell ◽  
Nuclear Proteins ◽  
Photographic Emulsion ◽  
Metaphase Chromosomes ◽  
Interphase Nuclei ◽  
Cell Layers ◽  
The Difference ◽  
Mitotic Figures ◽  
And Migration ◽  
Silver Grains

Hooded rats were given an intraperitoneal injection of 3H-tyrosine, and killed in pairs 10 min, 30 min, 12 h, 36 h, 7 days, and 30 days later. A piece of skin with white growing hair, and the tongue, were taken from each animal and radioautographs were prepared. Silver grains were counted over whole nuclei and whole mitotic figures of the germinal cells and whole nuclei of differentiating cells of both tissues. It was found that the interphase nuclei have significantly more silver grains over them than the chromosomes at all stages of mitosis and there are virtually no grains over metaphase, anaphase, and early telophase chromosomes in both tissues of all the animals killed up to 36 h after the injection. The difference between the grain counts over the interphase nuclei and the chromosomes of dividing cells is at least 20-fold at 30 min in the hair matrix, at least 5-fold at 30 min in the tongue and at 36 h in both tissues. It was established that the differences observed between the radioactivities of the nuclei and chromosomes of mitotic figures are real from estimates of: the radioactivity of the cell cytoplasm, volumes of the metaphase chromosomes and interphase nuclei within 1µ of the photographic emulsion, and the volumes of cytoplasm separating the photographic emulsion and these structures. No protein synthesis was demonstrable in the chromosomes during metaphase, anaphase, and early telophase. Nuclear proteins leave the chromosomes during prophase and prometaphase and return to the nucleus during late telophase. The cells in the matrix and upper bulb of the growing hair follicle and those in the germinal, prickle, and granular cell layers of the tongue are in different functional states; 30 min after injection of 3H-tyrosine they have different amounts of it in their nuclear proteins. It is suggested that the amount incorporated into each nucleus is related to the rate at which proteins are being synthesized by the cell.

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.

scholarly journals Arginine deprivation in KB cells: I. Effect on cell cycle progress

1977 ◽  
Vol 75 (3) ◽  
pp. 881-888 ◽  
Author(s):  
AS Weissfeld ◽  
H Rouse
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Experimental Period ◽  
Cell Multiplication ◽  
Starvation Period ◽  
Kb Cells ◽  
Insoluble Material ◽  
Cell Cycle Inhibition ◽  
Cellular Dna

When exponentially growing KB cells were deprived of arginine, cell multiplication ceased after 12 h but viability was maintained throughout the experimental period (42-48 h). Although tritiated thymidine ([(3)H]TdR) incorporation into acid-insoluble material declined to 5 percent of the initial rate, the fraction of cells engaged in DNA synthesis, determined by autoradiography, remained constant throughout the starvation period and approximately equal to the synthesizing fraction in exponentially growing controls (40 percent). Continous [(3)H]TdR-labeling indicated that 80 percent of the arginine-starved cells incorporated (3)H at some time during a 48-h deprivation period. Thus, some cells ceased DNA synthesis, whereas some initially nonsynthesizing cells initiated DNA synthesis during starvation. Flow microfluorometric profiles of distribution of cellular DNA contents at the end of the starvation period indicated that essentially no cells had a 4c or G2 complement. If arginine was restored after 30 h of starvation, cultures resumed active, largely asynchronous division after a 16-h lag. Autoradiographs of metaphase figures from cultures continuously labeled with [(3)H]TdR after restoration indicated that all cells in the culture underwent DNA synthesis before dividing. It was concluded that the majority of cells in arginine-starved cultures are arrested in neither a normal G1 nor G2. It is proposed that for an exponential culture, i.e. from most positions in the cell cycle, inhibition of cell growth after arginine with withdrawal centers on the ability of cells to complete replication of their DNA.

scholarly journals Differences in cell cycle characteristics among patients with acute nonlymphocytic leukemia

Blood ◽  
1987 ◽  
Vol 69 (6) ◽  
pp. 1647-1653 ◽  
Author(s):  
A Raza ◽  
Y Maheshwari ◽  
HD Preisler
Keyword(s):  
Cell Cycle ◽  
Tritiated Thymidine ◽  
S Phase ◽  
Total Cell ◽  
Acute Nonlymphocytic Leukemia ◽  
Cell Cycle Time ◽  
Myeloid Leukemias ◽  
History Of

The proliferative characteristics of myeloid leukemias were defined in vivo after intravenous infusions of bromodeoxyuridine (BrdU) in 40 patients. The percentage of S-phase cells obtained from the biopsies (mean, 20%) were significantly higher (P = .00003) than those determined from the bone marrow (BM) aspirates (mean, 9%). The post- BrdU infusion BM aspirates from 40 patients were incubated with tritiated thymidine in vitro. These double-labeled slides were utilized to determine the duration of S-phase (Ts) in myeloblasts and their total cell cycle time (Tc). The Ts varied from four to 49 hours (mean, 19 hours; median, 17 hours). Similarly, there were wide variations in Tc of individual patients ranging from 16 to 292 hours (mean, 93 hours; median, 76 hours). There was no relationship between Tc and the percentage of S-phase cells, but there was a good correlation between Tc and Ts (r = .8). Patients with relapsed acute nonlymphocytic leukemia (ANLL) appeared to have a longer Ts and Tc than those studied at initial diagnosis. A subgroup of patients at either extreme of Tc were identified who demonstrated clinically documented resistance in response to multiple courses of chemotherapy. We conclude that Ts and Tc provide additional biologic information that may be valuable in understanding the variations observed in the natural history of ANLL.

TGFbeta1 induces a cell-cycle-dependent increase in motility of epithelial cells

1999 ◽  
Vol 112 (4) ◽  
pp. 447-454 ◽  
Author(s):  
D. Zicha ◽  
E. Genot ◽  
G.A. Dunn ◽  
I.M. Kramer
Keyword(s):  
Cell Cycle ◽  
Mass Distribution ◽  
Transforming Growth Factor Beta ◽  
Time Course ◽  
Transforming Growth Factor ◽  
Interference Microscopy ◽  
Response To Treatment ◽  
Gradual Onset ◽  
The Difference ◽  
Cycle Dependent

We have previously shown that addition of type 1 transforming growth factor-beta (TGFbeta1) to an exponentially growing population of mink lung CCl64 cells increases their average intermitotic time from 14.4 to 20.3 hours, predominantly by extending G1 from 7.5 to 13.5 hours. Here we have used the DRIMAPS system (digitally recorded interference microscopy with automatic phase-shifting) for obtaining data on cellular mass distribution, cell motility and morphology. We found no significant change in the cells' rate of mass increase following TGFbeta1 treatment, which implies that the treated cells attained a higher mass during their extended cell cycle and this was confirmed by direct measurement of cell size. However, the cells showed a dramatic motile response to treatment: TGFbeta1-treated cells had a significantly higher time-averaged speed of 36.2 microm hour-1 compared to 14.5 microm hour-1 for the control cells. The time course of the response was gradual, reaching a maximum mean speed of 52.6 microm hour-1 after 15 hours exposure. We found that the gradual onset of the response was probably not due to a slow accumulation of a secondary factor but because cells were dividing throughout the experiment and most of the response to TGFbeta1 occurred only after the first cell division in its presence. Thus, taking only those cells that had not yet divided, the time-averaged speed of treated cells (26.1 micrometer hour-1) was only moderately higher than that of untreated cells (14.9 micrometer hour-1) whereas, for those cells that had divided, the difference in speed between treated cells (45.1 micrometer hour-1) and untreated cells (14.1 microm hour-1) was much greater. Increased speed was a consequence of enhanced protrusion and retraction of the cell margin coupled with an increase in cell polarity. TGFbeta1 also increased the mean spreading of the cells, measured as area-to-mass ratio, from 3.2 to 4.4 micrometer2 pg-1, and the intracellular mass distribution became more asymmetric. The observations indicate that a G2 signal may be necessary to reach maximal motility in the presence of TGFbeta1.

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