Properties of the primary organization field in the embryo of Xenopus laevis

Development ◽  
1973 ◽  
Vol 30 (1) ◽  
pp. 49-62
Author(s):  
J. Cooke
Keyword(s):  
Cell Cycle ◽  
Mitomycin C ◽  
Direct Method ◽  
Large Cell ◽  
Cell Number ◽  
Information Value ◽  
Cell Counting ◽  
Tail Bud ◽  
Cell Cycle Time ◽  
Essentially Normal

Visual observation of early blastulae, and counting of cell suspensions from the late blastula and subsequent stages of Xenopus development, have shown that exposure to either colcemid or mitomycin C can sustain blockage of the mitotic cycle, and hence prevent the normal increase in cell number. Such blockage is essentially complete within a period, following introduction of the drugs, which is short compared with the cell-cycle time normal to post-blastular stages. Although the cell-counting data do not allow a statistical demonstration, there is a suggestion that mitomycin C allows a greater proportion of cells to divide once, after its introduction, than does colcemid. This is in accord with its putative mode of action, in causing only intrachromatid cross-linkage within chromosones, but there are no data on the status of DNA replication within nuclei of the non-dividing cells under either drug. If blockage is begun not earlier than stage 10+, some 20 min after dorsal lip formation, essentially normal morphogenesis ensues up to tail-bud stages around 27, including histodifferentiation of ectodermal structures and notochord, and twitching of somitic muscle. Such embryos are described. In describing those arresting at earlier stages following blockage in blastulae, the possibility is mentioned that morphogenesis may fail for mechanical reasons due to low cell number and large cell size, rather than to lack of a normal field as such. Cell counting reveals that blocked embryos with qualitatively normal pattern formation by stages 22–24, in having a total cell number appropriate to stage 10+ or 10½, show about a seventh or an eighth of the number of cells normal to their stage. Between then and stage 27 when histogenesis, particularly of twitching muscle, is more clearly seen, the direct method of estimating cell number can no longer be used, but histology reveals no mitotic metaphases in any blocked embryos. In the same experiments, operations of two types described in previous papers are performed on early gastrulae so that regulation is required in the embryonic field after the cessation of mitosis. The results are as seen in the normal presence of the cell cycle, revealing that, in response to changes of positional information value, host material may change its presumptive differentiation tendency and final commitment, in the absence of cell division as such. There is some indication that the proportional numbers of cells assigned to different structures in an individuation field may deviate from normal when overall cell number is limiting.

Cell number in relation to primary pattern formation in the embryo of Xenopus laevis

Development ◽  
1979 ◽  
Vol 53 (1) ◽  
pp. 269-289
Author(s):  
Jonathan Cooke
Keyword(s):  
Cell Cycle ◽  
Pattern Formation ◽  
Cell Cycle Control ◽  
Cell Number ◽  
The Body ◽  
Morphological Evidence ◽  
Tail Bud ◽  
Cell Cycle Time ◽  
Mesodermal Cell ◽  
Body Pattern

Morphological evidence is presented that definitive mesoderm formation in Xenopus is best understood as extending to the end of the neurula phase of development. A process of recruitment of cells from the deep neurectoderm layers into mesodermal position and behaviour, strictly comparable with that already agreed to occur around the internal blastoporal ‘lip’ during gastrula stages, can be shown to continue at the posterior end of the presumptive body pattern up to stage 20 (earliest tail bud). Spatial patterns of incidence of mitosis are described for the fifteen hours of development between the late gastrula and stage 20–22. These are related to the onset of new cell behaviours and overt cyto-differentiations characterizing the dorsal axial pattern,which occur in cranio-caudal and then medio-lateral spatial sequence as development proceeds. A relatively abrupt cessation of mitosis, among hitherto asynchronously cycling cells,precedes the other changes at each level in the presumptive axial pattern. The widespread incidence of cells still in DNA synthesis, anterior to the last mitoses in the posterior-to-anteriordevelopmental sequence of axial tissue, strongly suggests that cells of notochord and somites in their prolonged, non-cycling phase are G2-arrested, and thus tetraploid. This is discussed in relation to what is known of cell-cycle control in other situations. Best estimates for cell-cycle time in the still-dividing, posterior mesoderm of the neurula lie between 10 and 15 h. The supposition of continuing recruitment from neurectoderm can resolve an apparent discrepancy whereby total mesodermal cell number nevertheless contrives to double over a period of approximately 12 h during neurulation when most of the cells are leaving the cycle. Because of pre-existing evidence that cells maintain their relative positions (despite distortion)during the movements that form the mesodermal mantle, the patterns presented in this paper can be understood in two ways: as a temporal sequence of developmental events undergone by individual, posteriorly recruited cells as they achieve their final positions in the body pattern, or alternatively as a succession of wavefronts with respect to changes of cellstate, passing obliquely across the presumptive body pattern in antero-posterior direction. These concepts are discussed briefly in relation to recent ideas about pattern formation in growing systems.

The effects of Streptomyces hyaluronidase on tissue organization and cell cycle time in rat embryos

Development ◽  
1986 ◽  
Vol 98 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Gillian M. Morriss-Kay ◽  
Fiona Tuckett ◽  
Michael Solursh
Keyword(s):  
Cell Cycle ◽  
Extracellular Matrix ◽  
Cycle Time ◽  
Cell Number ◽  
Considerable Reduction ◽  
Blue Staining ◽  
Neuroepithelial Cell ◽  
Cell Cycle Time ◽  
Rat Embryos ◽  
Tissue Organization

Day 9 rat embryos (late presomite stage with cranial neural plate or very early neural folds) were cultured for various periods of time from 6–48 h in medium containing 20 TRU ml−1Streptomyces hyaluronidase. Exposure to the enzyme resulted in considerable reduction of mesenchymal extracellular matrix. Access of the enzyme to the embryo was confirmed by alcian blue staining which indicated considerable reduction of extracellular and cell surface hyaluronate. Cranial neurulation was retarded, but not inhibited, and migration of both neural crest and primary mesenchyme cells occurred. In general, morphology was normal at 48 h. The major effect was on growth: embryos were smaller, with slightly reduced neuroepithelial cell number and greatly reduced mesenchymal cell number. Neuroepithelial cell cycle time was slightly prolonged, and that of the mesenchyme more than doubled. This differential effect on the growth rates of these two tissues reflects the normal distribution of hyaluronate, which is particularly abundant in the mesenchymal extracellular matrix.

scholarly journals Evaluation of a strategy for tumor-initiating stem cell eradication in primary human glioblastoma cultures as a model

2018 ◽  
Vol 22 (7) ◽  
pp. 825-836
Author(s):  
E. V. Dolgova ◽  
A. S. Proskurina ◽  
E. A. Potter ◽  
T. V. Tyrinova ◽  
O. S. Taranov ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Stem Cell ◽  
Mitomycin C ◽  
Primary Cultures ◽  
Cell Number ◽  
Cross Linking ◽  
Human Glioblastoma ◽  
Interstrand Cross Links

Primary cultures of human glioblastoma were obtained from the surgical material of patients K. (female, 61 years, Ds: relapse of glioblastoma) and Zh. (female, 60 years, Ds: relapse of glioblastoma). The effectiveness of a new therapeutic approach aimed at destroying the cancer cell community was evaluated on the primary cell lines of human glioblastoma culture by employing a new strategy of tumor-initiating stem cell synchronization and a domestic strategy of their eradication "3+1". The key elements of the strategy were the following indicator results: (1) evaluation of the presence of tumor-initiating stem cells in a population of cells from analyzed cultures by their ability to internalize double-stranded labeled DNA (TAMRA+ cells); (2) determination of the reference time points of the repair cycle of DNA interstrand cross-links induced by cross-linking cytostatic mitomycin C; (3) evaluation of cell cycle synchronization; (4) determination of the time (day after therapy initiation) when TAMRA+ cells were synchronously present in phase G1/S of the cell cycle, sensitive to the therapy; and (5) establishment of the TAMRA+ (tumor-initiating stem cells) eradication schedule. The cultures were treated with cross-linking cytostatic mitomycin C and a compositional DNA preparation. After the treatments, cell division slows down, and the cultures degrade. The K cell line completely degraded within 30 days of observation. The cell number of the Zh culture fell to nearly one-third of the starting value by day 15 of observation. On day 15, this indicator constituted 1/7.45 for mitomycin C and 1/10.28 for mitomycin C + DNA with reference to the control. The main target of the mitomycin C + DNA regimen was TAMRA+ tumor-initiating stem cells of the glioblastoma cell populations. The action of mitomycin C alone or in the combination with DNA demonstrated effective elimination of TAMRA+ tumor-initiating stem cells and the whole primary cultures of human glioblastomas.

The cell cycle during the vegetative stage of Dictyostelium discoideum and its response to temperature change

1978 ◽  
Vol 32 (1) ◽  
pp. 1-20
Author(s):  
I.M. Zada-Hames ◽  
J.M. Ashworth
Keyword(s):  
Cell Cycle ◽  
Stationary Phase ◽  
Dictyostelium Discoideum ◽  
Doubling Time ◽  
Nuclear Dna ◽  
Cell Number ◽  
Cell Cycle Time ◽  
Optimum Growth Temperature ◽  
Cell Cycle Phases ◽  
Response To Temperature

The cell cycle in amoebae of Dictyostelium discoideum has been analysed in cells growing asynchronously in axenic medium. For cells growing at the optimum growth temperature of 22 degrees C with a culture doubling time of 8 h the average times for the cell cycle phases are as follows: G1, 1.5 h; S, 2.1 h; G2, 4.4 h; M, 15.2 min. When amoebae are grown at temperatures below 22 degrees C, culture doubling time increases and the cell cycle phases are altered in ways characteristic for each phase. G2 is the most variable period and may occupy up to 70% of the total cell cycle time; S and G1 are the least affected, increasing by only 20% when the cell generation time is doubled. When cells which have reached the stationary phase of growth in liquid medium are washed and reinoculated into fresh medium they divide synchronously after a lag period of 5 h. By following cell number increase and nuclear DNA synthesis in these cultures we have shown that stationary phase cells are arrested in the G2 phase of the cell cycle. Finally, although more than 97% of amoebae grown on a bacterial food source are uninucleate, when grown axenically up to 35% of the cell population may become multinucleate. Our results suggest that these cells probably arise through the failure of cytokinesis to follow karyokinesis. Multinucleate cells appear to have a slightly longer G2 period than mononucleate cells.

OSI-027 alleviates oxaliplatin chemoresistance in gastric cancer cells by suppressing P-gp induction

2020 ◽  
Vol 20 ◽  
Author(s):  
En Xu ◽  
Hao Zhu ◽  
Feng Wang ◽  
Ji Miao ◽  
Shangce Du ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cell Cycle ◽  
Cancer Cells ◽  
Mammalian Target Of Rapamycin ◽  
Cell Counting ◽  
Gastric Cancer Cells ◽  
Ags Cells ◽  
Dual Inhibitor ◽  
Induced Apoptosis

: Gastric cancer is one of the most common malignancies worldwide and the third leading cause of cancer-related death. In the present study, we investigated the potential activity of OSI-027, a potent and selective mammalian target of rapamycin complex 1/2 (mTOR1/2) dual inhibitor, alone or in combination with oxaliplatin against gastric cancer cells in vitro. Cell counting kit-8 assays and EdU staining were performed to examine the proliferation of cancer cells. Cell cycle and apoptosis were detected by flow cytometry. Western blot was used to detect the elements of the mTOR pathway and Pgp in gastric cancer cell lines. OSI-027 inhibited the proliferation of MKN-45 and AGS cells by arresting the cell cycle in the G0/G1 phase. At the molecular level, OSI-027 simultaneously blocked mTORC1 and mTORC2 activation, and resulted in the downregulation of phosphor-Akt, phpspho-p70S6k, phosphor-4EBP1, cyclin D1, and cyclin-dependent kinase4 (CDK4). Additionally, OSI-027 also downregulated P-gp, which enhanced oxaliplatin-induced apoptosis and suppressed multidrug resistance. Moreover, OSI-027 exhibited synergistic cytotoxic effects with oxaliplatin in vitro, while a P-gp siRNA knockdown significantly inhibited the synergistic effect. In summary, our results suggest that dual mTORC1/mTORC2 inhibitors (e.g., OSI-027) should be further investigated as a potential valuable treatment for gastric cancer.

MITOMYCIN C INDUCED APOPTOSIS: INFLUENCE OF CELL CYCLE PHASE

1996 ◽  
Vol 88 (1-2) ◽  
pp. 82-82a ◽  
Author(s):  
Magali OLIVIER ◽  
Charles THEILLET
Keyword(s):  
Cell Cycle ◽  
Mitomycin C ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Induced Apoptosis

scholarly journals Mitomycin C Induces Apoptosis in Rheumatoid Arthritis Fibroblast-Like Synoviocytes via a Mitochondrial-Mediated Pathway

2015 ◽  
Vol 35 (3) ◽  
pp. 1125-1136 ◽  
Author(s):  
Chuqi Yan ◽  
Dechao Kong ◽  
Dong Ge ◽  
Yanming Zhang ◽  
Xishan Zhang ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Cell Viability ◽  
Mitomycin C ◽  
Apoptotic Cell ◽  
Chronic Inflammatory Disease ◽  
Cell Counting ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Control Treatment ◽  
Induced Apoptosis ◽  
Fibroblast Like Synoviocytes

Background/Aims: Rheumatoid arthritis (RA) is a systemic chronic inflammatory disease characterised by prominent synoviocyte hyperplasia and a potential imbalance between the growth and death of fibroblast-like synoviocytes (FLS). Mitomycin C (MMC) has previously been demonstrated to inhibit fibroblast proliferation and to induce fibroblast apoptosis. However, the effects of MMC on the proliferation and apoptosis of human RA FLS and the potential mechanisms underlying its effects remain unknown. Methods: Cell viability was determined using the Cell Counting Kit-8 assay. Apoptotic cell death was analysed via Annexin V-FITC/PI double staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling. The production of intracellular reactive oxygen species (ROS) was assessed via flow cytometry, and the changes in mitochondrial membrane potential (ΔΨm) were visualized based on JC-1 staining via fluorescence microscopy. The expression of apoptosis-related proteins was determined via Western blot. Results: Treatment with MMC significantly reduced cell viability and induced apoptosis in RA FLS. Furthermore, MMC exposure was found to stimulate the production of ROS and to disrupt the ΔΨm compared to the control treatment. Moreover, MMC increased the release of mitochondrial cytochrome c, the ratio of Bax/Bcl-2, the activation of caspase-9 and caspase-3, and the subsequent cleavage of poly(ADP-ribose) polymerase. Conclusion: Our findings suggest that MMC inhibits cell proliferation and induces apoptosis in RA FLS, and the mechanism underlying this MMC-induced apoptosis may involve a mitochondrial signalling pathway.

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.

Sign in / Sign up

Export Citation Format

Share Document