Experimental Approaches to the Preimplantation Ova with Emphasis on Cytoplasmic Factors, Cell Cycle and Intercellular Connections

1987 ◽  
pp. 196-212
Author(s):  
S. Suzuki ◽  
H. Kitai ◽  
S. Kurasawa ◽  
K. Yoda ◽  
S. Komatsu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cytoplasmic Factors ◽  
Experimental Approaches ◽  
Intercellular Connections

scholarly journals Automatic synchronisation of the cell cycle in budding yeast through closed-loop feedback control

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Giansimone Perrino ◽  
Sara Napolitano ◽  
Francesca Galdi ◽  
Antonella La Regina ◽  
Davide Fiore ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Autonomous Vehicles ◽  
Genetic System ◽  
Yeast Cells ◽  
Control Engineering ◽  
Loop Feedback ◽  
Experimental Approaches ◽  
Closed Loop Feedback ◽  
Theoretical Foundations

AbstractThe cell cycle is the process by which eukaryotic cells replicate. Yeast cells cycle asynchronously with each cell in the population budding at a different time. Although there are several experimental approaches to synchronise cells, these usually work only in the short-term. Here, we build a cyber-genetic system to achieve long-term synchronisation of the cell population, by interfacing genetically modified yeast cells with a computer by means of microfluidics to dynamically change medium, and a microscope to estimate cell cycle phases of individual cells. The computer implements a controller algorithm to decide when, and for how long, to change the growth medium to synchronise the cell-cycle across the population. Our work builds upon solid theoretical foundations provided by Control Engineering. In addition to providing an avenue for yeast cell cycle synchronisation, our work shows that control engineering can be used to automatically steer complex biological processes towards desired behaviours similarly to what is currently done with robots and autonomous vehicles.

scholarly journals Cyber-yeast: Automatic synchronisation of the cell cycle in budding yeast through closed-loop feedback control

2020 ◽  
Author(s):  
Giansimone Perrino ◽  
Sara Napolitano ◽  
Francesca Galdi ◽  
Antonella La Regina ◽  
Davide Fiore ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Autonomous Vehicles ◽  
Genetic System ◽  
Yeast Cells ◽  
Control Engineering ◽  
Loop Feedback ◽  
Experimental Approaches ◽  
Closed Loop Feedback ◽  
Theoretical Foundations

ABSTRACTThe cell cycle is the process by which eukaryotic cells replicate. Yeast cells cycle asynchronously with each cell in the population budding at a different time. Although there are several experimental approaches to “synchronise” cells, these work only in the short-term. Here, we built a cyber-genetic system to achieve long-term synchronisation of the cell population, by interfacing genetically modified yeast cells with a computer by means of microfluidics to dynamically change medium, and a microscope to estimate cell cycle phases of individual cells. The computer implements a “controller” algorithm to decide when, and for how long, to change the growth medium to synchronise the cell-cycle across the population. Our work builds upon solid theoretical foundations provided by Control Engineering. In addition to providing a new avenue for yeast cell cycle synchronisation, our work shows that computers can automatically steer complex biological processes towards desired behaviours similarly to what is currently done with robots and autonomous vehicles.

scholarly journals Characterizing stochastic cell cycle dynamics in exponential growth

2021 ◽  
Author(s):  
Dean Huang ◽  
Teresa Lo ◽  
Houra Merrikh ◽  
Paul A. Wiggins
Keyword(s):  
Cell Cycle ◽  
Stochastic Model ◽  
Cell Biology ◽  
Deterministic Model ◽  
Time Lapse ◽  
Distribution Functions ◽  
Cell Cycles ◽  
Experimental Approaches ◽  
Deterministic Description ◽  
Cell Cycle Dynamics

Two powerful and complementary experimental approaches are commonly used to study the cell cycle and cell biology: One class of experiments characterizes the statistics (or demographics) of an unsynchronized exponentially-growing population, while the other captures cell cycle dynamics, either by time-lapse imaging of full cell cycles or in bulk experiments on synchronized populations. In this paper, we study the subtle relationship between observations in these two distinct experimental approaches. We begin with an existing model: a single-cell deterministic description of cell cycle dynamics where cell states (i.e. periods or phases) have precise lifetimes. We then generalize this description to a stochastic model in which the states have stochastic lifetimes, as described by arbitrary probability distribution functions. Our analyses of the demographics of an exponential culture reveal a simple and exact correspondence between the deterministic and stochastic models: The corresponding state lifetimes in the deterministic model are equal to the exponential mean of the lifetimes in the stochastic model. An important implication is therefore that the demographics of an exponential culture will be well-fit by a deterministic model even if the state timing is stochastic. Although we explore the implications of the models in the context of the Escherichia coli cell cycle, we expect both the models as well as the significance of the exponential-mean lifetimes to find many applications in the quantitative analysis of cell cycle dynamics in other biological systems.

scholarly journals A previously missed population of antigen-specific CD8 T cells divides in the blood after vaccination

2018 ◽  
Author(s):  
Sonia Simonetti ◽  
Ambra Natalini ◽  
Antonella Folgori ◽  
Stefania Capone ◽  
Alfredo Nicosia ◽  
...  
Keyword(s):  
Cell Cycle ◽  
T Cells ◽  
Cd8 T Cells ◽  
Viral Vectors ◽  
Clonal Expansion ◽  
Leukemic Cells ◽  
Analysis Technique ◽  
Dividing Cells ◽  
Experimental Approaches ◽  
A Site

AbstractAlthough clonal expansion is a hallmark of adaptive immunity, the location(s) where antigen-responding T cells enter cell cycle and complete it have been poorly explored. This lack of knowledge stems partially from the limited experimental approaches available. By using Ki67 plus DNA staining and a novel data analysis technique, we distinguished antigen-specific CD8 T cells in G0, in G1, and in S-G2-M phases after intramuscular vaccination of BALB/c mice with antigen-expressing viral vectors. We discovered an entire population of cycling cells that are usually missed. This “extra” population was present early after vaccination in lymph nodes, spleen and, surprisingly, also in the blood, which is not expected to be a site for mitosis of normal non-leukemic cells. These results have implications for previous and future immunological studies in animal models, and potentially in humans. They might also inspire hematologists to seek for other missed populations of dividing cells in blood.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Fibronexus-Like Adhesion Sites are Present at the Invasive Zones of Human Epidermoid Carcinomas

1982 ◽  
Vol 40 ◽  
pp. 106-109
Author(s):  
Irwin I. Singer
Keyword(s):  
Cell Cycle ◽  
Serum Concentration ◽  
Substrate Binding ◽  
High Serum ◽  
Adhesion Sites ◽  
Substrate Adhesion ◽  
Focal Contacts ◽  
Adhesion Complex ◽  
Low Serum

Our previous results indicate that two types of fibronectin-cytoskeletal associations may be formed at the fibroblast surface: dorsal matrixbinding fibronexuses generated in high serum (5% FBS) cultures, and ventral substrate-adhering units formed in low serum (0.3% FBS) cultures. The substrate-adhering fibronexus consists of at least vinculin (VN) and actin in its cytoplasmic leg, and fibronectin (FN) as one of its major extracellular components. This substrate-adhesion complex is localized in focal contacts, the sites of closest substratum approach visualized with interference reflection microscopy, which appear to be the major points of cell-tosubstrate adhesion. In fibroblasts, the latter substrate-binding complex is characteristic of cultures that are arrested at the G1 phase of the cell cycle due to the low serum concentration in their medium. These arrested fibroblasts are very well spread, flattened, and immobile.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

Immunocytochemical studies on the behavior of RuBisCO and LHCP II during the cell cycle of synchronized Euglena gracilis

1990 ◽  
Vol 48 (3) ◽  
pp. 662-663
Author(s):  
Tetsuaki Osafune ◽  
Shuji Sumida ◽  
Tomoko Ehara ◽  
Eiji Hase ◽  
Jerome A. Schiff
Keyword(s):  
Cell Cycle ◽  
Immunoelectron Microscopy ◽  
Growth Phase ◽  
Euglena Gracilis ◽  
Dark Period ◽  
Light Period ◽  
Carboxylase Activity ◽  
Immunocytochemical Studies ◽  
Lhcp Ii

Changes in the morphology of pyrenoid and the distribution of RuBisCO in the chloroplast of Euglena gracilis were followed by immunoelectron microscopy during the cell cycle in a light (14 h)- dark (10 h) synchronized culture under photoautotrophic conditions. The imrnunoreactive proteins wereconcentrated in the pyrenoid, and less densely distributed in the stroma during the light period (growth phase, Fig. 1-2), but the pyrenoid disappeared during the dark period (division phase), and RuBisCO was dispersed throughout the stroma. Toward the end of the division phase, the pyrenoid began to form in the center of the stroma, and RuBisCO is again concentrated in that pyrenoid region. From a comparison of photosynthetic CO2-fixation with the total carboxylase activity of RuBisCO extracted from Euglena cells in the growth phase, it is suggested that the carboxylase in the pyrenoid functions in CO2-fixation in photosynthesis.

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