scholarly journals Cell Cycle Kinetics and Development of Hydra Attenuata

1974 ◽  
Vol 16 (2) ◽  
pp. 349-358 ◽  
Author(s):  
R. D. CAMPBELL ◽  
C. N. DAVID
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
Cell Function ◽  
Control Point ◽  
Interstitial Cells ◽  
Total Cell ◽  
Cycle Duration ◽  
Cell Cycles ◽  
Cell Cycle Duration ◽  
Hydra Attenuata

The cell cycle parameters of interstitial cells in Hydra attenuata have been determined. Interstitial cells were classified according to cluster size in which they occur (1, 2, 4, 8 or 16 cells) and morphology using maceration preparations and histological sections. The lengths of G1, S, G2 and M were determined by standard methods of cell cycle analysis using pulse-chase and continuous labelling with [3H]- and [14C]thymidine. Nuclear DNA contents were measured microfluorimetrically. All classes of interstitial cells proliferate but the cell cycle of large interstitial cells occurring singly or in pairs is longer than that of interstitial cells occurring in clusters of 4, 8 and 16 cells. The S-phase is 11-12 h long and G1 is less than 1 h for all classes of interstitial cells. G2 is 3-4 h long for interstitial cells in clusters of 4, 8 and 16 cells giving these cells a total cell cycle duration of 16-17 h. In contrast, large interstitial cells occurring as singles and in clusters of 2 have G2 durations ranging from 4 to 22 h. Two subpopulations can be discerned among these cells, one having a G1 of about 6 h and a total cell cycle of about 19 h, the other having an average G2 of 14 h and a total cell cycle of about 27 h. The differences in cell cycle duration appear to be associated with interstitial cell function. Cells having a short cell cycle are probably committed to nematocyte differentiation, while large interstitial cells having long and variable cell cycles appear to be undetermined stem cells responsible for proliferating further interstitial cells. The variable length of G2 in these cells suggest it as a possible control point.

158 RELATIONSHIP BETWEEN FOURTH CELL CYCLE DURATION AND POST-TRANSFER VIABILITY IN IN VITRO-FERTILIZED BOVINE EMBRYOS

2012 ◽  
Vol 24 (1) ◽  
pp. 191
Author(s):  
S. Sugimura ◽  
Y. Hashiyada ◽  
Y. Aikawa ◽  
M. Ohtake ◽  
H. Matsuda ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Embryo Transfer ◽  
T Test ◽  
Cycle Duration ◽  
Bovine Embryos ◽  
Cell Cycles ◽  
Cell Cycle Duration ◽  
Student’S T ◽  
Student’S T Test

In cattle, the prediction of embryonic viability after embryo transfer is an important research target. A previous study has indicated that the duration of the fourth cell cycle at the time of maternal-zygotic transition, which is involved in in vitro embryonic development, may be an indicator of blastocyst formation; this study showed that embryos with a short fourth cell cycle have a better potential of developing into blastocysts than those with a long fourth cell cycle (Lequarre et al. 2003 Biol. Reprod. 69, 1707–1713). However, the relationship between the fourth cell cycle duration and post-transfer viability of embryos is unclear. The aim of the present study was to examine the effect of the fourth cell cycle duration on embryo development after embryo transfer. Twenty-five IVF bovine embryos were cultured in well-of-the-well culture dishes contained 125 μ of CR1aa supplemented with 5% calf serum at 38.5°C in 5% O2 and 5% CO2 for 168 h after insemination. In vitro development of the embryos was monitored using time-lapse cinematography (Sugimura et al. 2010 Biol. Reprod. 83, 970–978). We found that 61% of the blastocysts had a long fourth cell cycle (41.5 ± 5.9 h), which is commonly referred to as the lag phase, whereas the remaining embryos had a short fourth cell cycle (7.4 ± 4.5 h). All the embryos with a short fourth cell cycle exhibited a lag phase in the next cell cycle (32.9 ± 6.6 h). Moreover, embryos with a short fourth cell cycle were found to have a higher blastocyst rate (75.8%) than those with a long fourth cell cycle (48.1%; Student's t-test, P < 0.01). However, embryonic cell number, apoptosis incidence, chromosomal abnormality and O2 consumption were found to be identical between the 2 groups (Student's t-test, P > 0.05). Real-time reverse-transcription PCR results of the individual blastocysts showed that the relative expression of 5 genes related to pregnancy reorganization, placentation and fetal growth—namely, CDX2, IFN-τ, PLAC8, AKR1B1 and IGF2R—did not differ between the 2 groups (Student's t-test, P > 0.05). Furthermore, blastocysts derived from embryos with long (n = 30) and short (n = 19) fourth cell cycles were transferred into 49 recipient cows; we did not observe any difference between the long and short fourth cell cycles on the rates of pregnancy (long vs short fourth cell cycle, 30.0 vs 52.6%) and delivery (long vs short fourth cell cycle, 30.0 vs 47.4%; Yates' corrected chi-square test, P > 0.10). These results show that blastocysts derived from embryos with either long or short fourth cell cycles have identical developmental competence after embryo transfer. Therefore, the fourth cell cycle duration during maternal-zygotic transition appears to be unavailable as the indicator of post-transfer viability of IVF bovine embryos. This work was supported by the Research and Developmental Program for New Bio-Industry Initiatives.

scholarly journals The Effect of Dia2 Protein Deficiency on the Cell Cycle, Cell Size, and Recruitment of Ctf4 Protein in Saccharomyces cerevisiae

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 97
Author(s):  
Aneliya Ivanova ◽  
Aleksandar Atemin ◽  
Sonya Uzunova ◽  
Georgi Danovski ◽  
Radoslav Aleksandrov ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Cell Size ◽  
Ubiquitin Ligase ◽  
Driving Forces ◽  
S Phase ◽  
Cycle Duration ◽  
Cell Cycles ◽  
Cell Cycle Duration

Cells have evolved elaborate mechanisms to regulate DNA replication machinery and cell cycles in response to DNA damage and replication stress in order to prevent genomic instability and cancer. The E3 ubiquitin ligase SCFDia2 in S. cerevisiae is involved in the DNA replication and DNA damage stress response, but its effect on cell growth is still unclear. Here, we demonstrate that the absence of Dia2 prolongs the cell cycle by extending both S- and G2/M-phases while, at the same time, activating the S-phase checkpoint. In these conditions, Ctf4—an essential DNA replication protein and substrate of Dia2—prolongs its binding to the chromatin during the extended S- and G2/M-phases. Notably, the prolonged cell cycle when Dia2 is absent is accompanied by a marked increase in cell size. We found that while both DNA replication inhibition and an absence of Dia2 exerts effects on cell cycle duration and cell size, Dia2 deficiency leads to a much more profound increase in cell size and a substantially lesser effect on cell cycle duration compared to DNA replication inhibition. Our results suggest that the increased cell size in dia2∆ involves a complex mechanism in which the prolonged cell cycle is one of the driving forces.

scholarly journals Positive Feedback Between PU.1 and the Cell Cycle Controls Myeloid Differentiation

Science ◽  
2013 ◽  
Vol 341 (6146) ◽  
pp. 670-673 ◽  
Author(s):  
Hao Yuan Kueh ◽  
Ameya Champhekar ◽  
Stephen L. Nutt ◽  
Michael B. Elowitz ◽  
Ellen V. Rothenberg
Keyword(s):  
Cell Cycle ◽  
Cell Fate ◽  
Positive Feedback ◽  
Regulatory Gene ◽  
Control Cell ◽  
Stem Cell Differentiation ◽  
Myeloid Differentiation ◽  
Cycle Duration ◽  
Gene Circuits ◽  
Cell Cycles

Regulatory gene circuits with positive-feedback loops control stem cell differentiation, but several mechanisms can contribute to positive feedback. Here, we dissect feedback mechanisms through which the transcription factor PU.1 controls lymphoid and myeloid differentiation. Quantitative live-cell imaging revealed that developing B cells decrease PU.1 levels by reducing PU.1 transcription, whereas developing macrophages increase PU.1 levels by lengthening their cell cycles, which causes stable PU.1 accumulation. Exogenous PU.1 expression in progenitors increases endogenous PU.1 levels by inducing cell cycle lengthening, implying positive feedback between a regulatory factor and the cell cycle. Mathematical modeling showed that this cell cycle–coupled feedback architecture effectively stabilizes a slow-dividing differentiated state. These results show that cell cycle duration functions as an integral part of a positive autoregulatory circuit to control cell fate.

Genome in toto

Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 361-362 ◽  
Author(s):  
Alexander E Vinogradov
Keyword(s):  
Cell Cycle ◽  
Genome Evolution ◽  
Genome Size ◽  
Cycle Duration ◽  
Noncoding Dna ◽  
Cell Cycle Duration ◽  
The Relationship

At a certain temperature, which is a compromise for temperatures at which the species are adapted, the relationship between genome size and cell cycle duration during synchronous cleavage divisions can be very strong (r = 1.00, P < 0.01) in four closely related frogs, suggesting a functional dependence.Key words: genome size, genome evolution, genome cytoecology, noncoding DNA, cell cycle duration.

scholarly journals Lateral Root Priming Synergystically Arises from Root Growth and Auxin Transport Dynamics

2018 ◽  
Author(s):  
Thea van den Berg ◽  
Kirsten H. ten Tusscher
Keyword(s):  
Cell Cycle ◽  
Root Growth ◽  
Lateral Root ◽  
Root Formation ◽  
Growth Dynamics ◽  
Root Tip ◽  
Cycle Duration ◽  
Elongation Zone ◽  
Lateral Root Formation ◽  
Cell Cycle Duration

AbstractThe root system is a major determinant of plant fitness. Its capacity to supply the plant with sufficient water and nutrients strongly depends on root system architecture, which arises from the repeated branching off of lateral roots. A critical first step in lateral root formation is priming, which prepatterns sites competent of forming a lateral root. Priming is characterized by temporal oscillations in auxin, auxin signalling and gene expression in the root meristem, which through growth become transformed into a spatially repetitive pattern of competent sites. Previous studies have demonstrated the importance of auxin synthesis, transport and perception for the amplitude of these oscillations and their chances of producing an actual competent site. Additionally, repeated lateral root cap apoptosis was demonstrated to be strongly correlated with repetitive lateral root priming. Intriguingly, no single mutation has been identified that fully abolishes lateral root formation, and thusfar the mechanism underlying oscillations has remained unknown. In this study, we investigated the impact of auxin reflux loop properties combined with root growth dynamics on priming, using a computational approach. To this end we developed a novel multi-scale root model incorporating a realistic root tip architecture and reflux loop properties as well as root growth dynamics. Excitingly, in this model, repetitive auxin elevations automatically emerge. First, we show that root tip architecture and reflux loop properties result in an auxin loading zone at the start of the elongation zone, with preferential auxin loading in narrow vasculature cells. Second, we demonstrate how meristematic root growth dynamics causes regular alternations in the sizes of cells arriving at the elongation zone, which subsequently become amplified during cell expansion. These cell size differences translate into differences in cellular auxin loading potential. Combined, these properties result in temporal and spatial fluctuations in auxin levels in vasculature and pericycle cells. Our model predicts that temporal priming frequency predominantly depends on cell cycle duration, while cell cycle duration together with meristem size control lateral root spacing.

scholarly journals Effects of cell cycle variability on lineage and population measurements of mRNA abundance

2020 ◽  
Author(s):  
Ruben Perez-Carrasco ◽  
Casper Beentjes ◽  
Ramon Grima
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Negative Binomial ◽  
Eukaryotic Cell ◽  
Cycle Duration ◽  
Cell Cycle Duration ◽  
Monotonically Decreasing Function ◽  
Binomial Mixture ◽  
A Cell ◽  
The Mean

AbstractMany models of gene expression do not explicitly incorporate a cell cycle description. Here we derive a theory describing how mRNA fluctuations for constitutive and bursty gene expression are influenced by stochasticity in the duration of the cell cycle and the timing of DNA replication. Analytical expressions for the moments show that omitting cell cycle duration introduces an error in the predicted mean number of mRNAs that is a monotonically decreasing function of η, which is proportional to the ratio of the mean cell cycle duration and the mRNA lifetime. By contrast, the error in the variance of the mRNA distribution is highest for intermediate values of η consistent with genome-wide measurements in many organisms. Using eukaryotic cell data, we estimate the errors in the mean and variance to be at most 3% and 25%, respectively. Furthermore, we derive an accurate negative binomial mixture approximation to the mRNA distribution. This indicates that stochasticity in the cell cycle can introduce fluctuations in mRNA numbers that are similar to the effect of bursty transcription. Finally, we show that for real experimental data, disregarding cell cycle stochasticity can introduce errors in the inference of transcription rates larger than 10%.

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