Cell proliferation in the developing wing-bud of normal and talpid3 mutant chick embryos

Development ◽  
1975 ◽  
Vol 34 (3) ◽  
pp. 589-607
Author(s):  
D. A. Ede ◽  
O. P. Flint ◽  
P. Teague
Keyword(s):  
Cell Cycle ◽  
Early Stage ◽  
Mitotic Rate ◽  
Mitotic Division ◽  
Chick Embryos ◽  
Division Rate ◽  
Cell Cycle Time ◽  
Continuous Sampling ◽  
Wing Bud ◽  
Marked Drop

Previous measurements on mitotic division rate or cell cycle time have been made on samples from a few discrete limb regions or by continuous sampling, but only down a unidimensional limb axis, disregarding morphological discontinuities such as the presence or absence of cartilage. This study presents a new analysis on normal and talpid3 mutant chick embryos, measuring mitotic rate and also cell density through the central proximo-distal axis and at the limb periphery, taking into account the development of cartilage regions. Differentiation of cartilage is correlated with a marked drop in mitotic rate, accounting for a proximo-distal gradient of mitosis in central counts which was not observed at the limb periphery. Talpid3 limbs at an early stage show a central mitotic gradient, but the reverse of that observed in normal limbs.

scholarly journals Accelerated cell-cycling of hematopoietic progenitor cells by growth factors

Blood ◽  
1995 ◽  
Vol 86 (1) ◽  
pp. 73-79 ◽  
Author(s):  
R Tanaka ◽  
N Katayama ◽  
K Ohishi ◽  
N Mahmud ◽  
R Itoh ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Factors ◽  
Progenitor Cells ◽  
Early Stage ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Progenitor ◽  
Cell Cycle Time ◽  
Cell Cycling

Recent advances in molecular biology have led to the identification of hematopoietic growth factors that support and influence the proliferation of hematopoietic progenitor cells in vitro and in vivo. Although these factors have been extensively studied, little is known of their role in the regulation of cell-cycling of hematopoietic progenitors, especially in the early stage of hematopoiesis. In the present study, we examined the effects of early acting growth factors on proliferative kinetics of hematopoietic progenitors by monitoring the number of cells in individual developing colonies, using an in vitro clonal assay. Interleukin-11 (IL-11) or steel factor (SF), alone or in combination, shortened the time for the size of IL-3-dependent colonies to double. Consecutive replating experiments provided evidence for direct action of growth factors on the growth rate of hematopoietic progenitor cells. Shortening of the time for the total cell number in the colonies to double was due to a reduction in time for each single cell within the respective colonies to become two daughter cells, and there was no alteration in the incidence of cells with a proliferative capacity. Cell-cycle analysis demonstrated that IL-11 has the potential to induce a shortened time for cell-cycle of hematopoietic progenitor cells without affecting distribution of each fraction of the cell- cycle, whereas SF has the potential to reduce cell-cycle time mainly by decreasing the time required for hematopoietic progenitor cells to go through the G1 phase. These results suggest that growth factors may modulate cell-cycling of hematopoietic progenitor cells.

scholarly journals Cell Cycle, Division Rate, and Feeding of the Heterotroph Phalacroma rotundatum in a Chilean Fjord

2019 ◽  
Vol 7 (10) ◽  
pp. 451
Author(s):  
Patricio A. Díaz ◽  
Iván Pérez-Santos ◽  
Gonzalo Álvarez ◽  
Michael Araya ◽  
Francisco Álvarez ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Austral Summer ◽  
Field Studies ◽  
Local Characteristic ◽  
Reference List ◽  
Shellfish Poisoning ◽  
Division Rate ◽  
Bottom Waters ◽  
Harmful Microalgae ◽  
And Behavior

Phalacroma rotundatum is a rare cosmopolitan heterotrophic dinoflagellate. This species, included in the IOC-UNESCO Taxonomic Reference List of Harmful Microalgae, may be a diarrhetic shellfish poisoning (DSP) toxin vector, but little is known about its ecophysiology and behavior. A vertical net haul collected during the austral summer of 2018 in Reloncaví Sound (Chilean Patagonia) revealed an unusually abundant population of P. rotundatum and prompted intensive 24 h sampling on 16–17 January to study the cell cycle and feeding behavior of this species. Hydrographic measurements from a buoy revealed the local characteristic estuarine circulation, with a brackish surface layer (salinity 26–28) separated from saltier, colder bottom waters by a pycnocline at a depth modulated by the tidal regime. A high proportion of P. rotundatum cells were packed with digestive vacuoles (peak of 70% at 14:00), and phased cell division (µ = 0.46 d−1) occurred 3 h after sunrise. The division time (TD) was 2 h. This is the first cell cycle study of P. rotundatum. The results here disagree with those of previous field studies that considered asynchronous division in some Dinophysis species to be related to heterotrophic feeding. They also question the very specific prey requirements, Tiarina fusus, reported for P. rotundatum in northern Europe.

scholarly journals Mutational analyses of fs(1)Ya, an essential, developmentally regulated, nuclear envelope protein in Drosophila.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1473-1481 ◽  
Author(s):  
J Liu ◽  
K Song ◽  
M F Wolfner
Keyword(s):  
Cell Cycle ◽  
Embryonic Development ◽  
Nuclear Envelope ◽  
Envelope Protein ◽  
Chromatin Condensation ◽  
Cell Cycle Control ◽  
Nuclear Lamina ◽  
Mitotic Division ◽  
Developmentally Regulated ◽  
Egg Maturation

Abstract The fs(1)Ya protein (YA) is an essential, maternally encoded, nuclear lamina protein that is under both developmental and cell cycle control. A strong Ya mutation results in early arrest of embryos. To define the function of YA in the nuclear envelope during early embryonic development, we characterized the phenotypes of four Ya mutants alleles and determined their molecular lesions. Ya mutant embryos arrest with abnormal nuclear envelopes prior to the first mitotic division; a proportion of embryos from two leaky Ya mutants proceed beyond this but arrest after several abnormal divisions. Ya unfertilized eggs contain nuclei of different sizes and condensation states, apparently due to abnormal fusion of the meiotic products immediately after meiosis. Lamin is localized at the periphery of the uncondensed nuclei in these eggs. These results suggest that YA function is required during and after egg maturation to facilitate proper chromatin condensation, rather than to allow a lamin-containing nuclear envelope to form. Two leaky Ya alleles that partially complement have lesions at opposite ends of the YA protein, suggesting that the N- and C-termini are important for YA function and that YA might interact with itself either directly or indirectly.

scholarly journals Molecular cloning of a novel chemokine receptor-like gene from early stage chick embryos

IUBMB Life ◽  
1998 ◽  
Vol 44 (4) ◽  
pp. 673-681 ◽  
Author(s):  
Shalley Gupta ◽  
Kodandaram Pillarisetti ◽  
Samantha Gray ◽  
Jeffrey Stadel
Keyword(s):  
Molecular Cloning ◽  
Chemokine Receptor ◽  
Early Stage ◽  
Chick Embryos

scholarly journals Scheduling Chemotherapy: Catch 22 between Cell Kill and Resistance Evolution

2000 ◽  
Vol 2 (3) ◽  
pp. 215-232 ◽  
Author(s):  
Shea N. Gardner
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Drug Exposure ◽  
Drug Application ◽  
Growth Fraction ◽  
Cycle Phase ◽  
Response Curves ◽  
Division Rate ◽  
Drug Concentrations ◽  
Cns Drugs

Dose response curves show that prolonged drug exposure at a low concentration may kill more cells than short exposures at higher drug concentrations, particularly for cell cycle phase specific drugs. Applying drugs at low concentrations for prolonged periods, however, allows cells with partial resistance to evolve higher levels of resistance through stepwise processes such as gene amplification. Models are developed for cell cycle specific (CS) and cell cycle nonspecific (CNS) drugs to identify the schedule of drug application that balances this tradeoff.The models predict that a CS drug may be applied most effectively by splitting the cumulative dose into many (>40) fractions applied by long-term chemotherapy, while CNS drugs may be better applied in fewer than 10 fractions applied over a shorter term. The model suggests that administering each fraction by continuous infusion may be more effective than giving the drug as a bolus, whether the drug is CS or CNS. In addition, tumors with a low growth fraction or slow rate of cell division are predicted to be controlled more easily with CNS drugs, while those with a high proliferative fraction or fast cell division rate may respond better to CS drugs.

Cell Proliferation Kinetics of the Intramuscularly Implanted Lewis Lung Carcinoma

1980 ◽  
Vol 66 (6) ◽  
pp. 669-675 ◽  
Author(s):  
Gianna Badaracco ◽  
Claudia Greco ◽  
Giuseppe Starace
Keyword(s):  
Lung Carcinoma ◽  
Lewis Lung Carcinoma ◽  
Early Stage ◽  
Cell Loss ◽  
Lewis Lung ◽  
Phase Duration ◽  
Cell Cycle Time ◽  
Tumor Implantation ◽  
Kinetics Of ◽  
Carcinoma Tumor

The growth kinetics of the Lewis lung carcinoma tumor was studied. The main proliferative parameters of an early stage of the growth (8th day after tumor implantation) were derived from the analysis of the growth curve and the fraction of labeled mitoses (FLM curve). The occurrence of proliferative changes due to the transplantation was confirmed. The main variations observed concern a shortening of the cell cycle time, a prolongation of the S phase duration and an increase in cell loss. A critical analysis of the results of this preliminary study is reported.

scholarly journals Cell cycle dynamics of NG2 cells in the postnatal and ageing brain

2009 ◽  
Vol 5 (3-4) ◽  
pp. 57-67 ◽  
Author(s):  
Konstantina Psachoulia ◽  
Francoise Jamen ◽  
Kaylene M. Young ◽  
William D. Richardson
Keyword(s):  
Cell Cycle ◽  
Corpus Callosum ◽  
Biological Significance ◽  
Growth Fraction ◽  
Cell Cycle Time ◽  
Active Population ◽  
Dorsal Telencephalon ◽  
Ng2 Cells ◽  
Cell Cycle Dynamics ◽  
Ageing Brain

Oligodendrocyte precursors (OLPs or ‘NG2 cells’) are abundant in the adult mouse brain, where they continue to proliferate and generate new myelinating oligodendrocytes. By cumulative BrdU labelling, we estimated the cell cycle timeTCand the proportion of NG2 cells that is actively cycling (the growth fraction) at ~ postnatal day 6 (P6), P60, P240 and P540. In the corpus callosum,TCincreased from <2 days at P6 to ~9 days at P60 to ~70 days at P240 and P540. In the cortex,TCincreased from ~2 days to >150 days over the same period. The growth fraction remained relatively invariant at ~50% in both cortex and corpus callosum – that is, similar numbers of mitotically active and inactive NG2 cells co-exist at all ages. Our data imply that a stable population of quiescent NG2 cells appears before the end of the first postnatal week and persists throughout life. The mitotically active population acts as a source of new oligodendrocytes during adulthood, while the biological significance of the quiescent population remains to be determined. We found that the mitotic status of adult NG2 cells is unrelated to their developmental site of origin in the ventral or dorsal telencephalon. We also report that new oligodendrocytes continue to be formed at a slow rate from NG2 cells even after P240 (8 months of age).

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 A small increase in CHEK1 activity leads to the arrest of the first zygotic division in human

2020 ◽  
Author(s):  
Beili Chen ◽  
Jianying Guo ◽  
Ting Wang ◽  
Qianhui Lee ◽  
Jia Ming ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mitotic Checkpoint ◽  
Mitotic Division ◽  
Fine Tuning ◽  
Human Reproduction ◽  
Cycle Arrest ◽  
Assisted Human Reproduction ◽  
C Terminus ◽  
Low Concentrations

ABSTRACTThe first mitotic division in mammalian zygotes is unique. The fertilized egg reactivates its cell cycle, and the maternal and paternal genomes start to reprogram to become totipotent. The first division is very sensitive to a range of perturbations, particularly the DNA damage, leading to the embryo’s failure to enter the first mitosis. We discovered that a point mutation in the human CHEK1 gene resulted in an Arginine 442 to Glutamine change at the C-terminus of the CHEK1 protein. CHEK1 R442Q mutation caused the zygote to arrest just before the first division. Heterozygote individuals appeared to be healthy except that the female carriers are infertile. Expressing the corresponding mouse mutant Chk1 protein in zygotes also caused arrest before the first mitosis. Treating Chk1 R442Q mouse zygotes with low concentrations of CHEK1 inhibitor enabled the embryos to overcome the cell cycle arrest and resume normal development. Our results revealed an unexpected zygote mitotic checkpoint, which is extremely sensitive to the CHEK1 kinase activity. The fine-tuning of the DNA damage checkpoint permits the arrested one-cell embryos to overcome the first mitotic block and develop into healthy animals. These findings have important implications in assisted human reproduction.

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