Visualisation des centres générateurs selon la théorie phyllotaxique de Plantefol, dans le point végétatif du grand frêne (Fraxinus excelsior)

1984 ◽  
Vol 62 (12) ◽  
pp. 2636-2643 ◽  
Author(s):  
Alain Cottignies
Keyword(s):  
Cell Proliferation ◽  
Mitotic Activity ◽  
Poisson Distribution ◽  
Shoot Apex ◽  
Unit Area ◽  
Fraxinus Excelsior ◽  
Nearest Neighbour ◽  
Axial Zone ◽  
Cell Cycles ◽  
Mitotic Wave

To visualize the generative center of each foliar helix and its oriented progression, cell proliferation was studied in the ash (Fraxinus excelsior L.) shoot apex. The distribution of mitosis was analysed first with the hypothesis of the multiple foliar helices phyllotactic theory and then without any preliminary hypothesis. The cell cycles were asynchronic and mitotic duration was constant. Therefore, the parameters of both the Poisson distribution of mitosis in each apical zone and of mitotic density, evaluated by the nearest-neighbour method or by the rotation of a unit area, were indicative of the cell proliferation level. The axial zone differed from the initiating ring by virtue of its lower mitotic activity. The initiating ring was heterogeneous and involved two parts which were opposite each other and symmetrical with regard to the axis of the apex. In each half, the cell proliferation increased gradually to a generative center with a maximal mitotic activity, then decreased twice as fast. This heterogeneity showed the necessary rotation of a privileged mitotic wave, which progressed step by step in a single direction. The cartography of the cell proliferation intensity was mapped for one sample meristcm.

Influence de la photopériode sur le comportement du méristème caulinaire du Celosia cristata

1977 ◽  
Vol 55 (11) ◽  
pp. 1488-1500
Author(s):  
D. Driss-Ecole
Keyword(s):  
Mitotic Activity ◽  
Shoot Apex ◽  
Unstable State ◽  
Axial Zone ◽  
Histological Studies ◽  
Daily Show ◽  
Differentiated Cells ◽  
Long Day ◽  
Celosia Cristata ◽  
High Level

Three groups of plants of Celosia cristata were grown in a 8-h, 12-h, or 16-h day. Histological studies of the shoot apex were performed during the vegetative and the prefloral phases.The apical meristems of the plants subjected to long-day conditions (16 h) flatten (fasciation). At the beginning of the fasciation, an activation of the corpus and a restructuration of the meristem are observed. The transformed meristem shows four superficial layers which cover a group of differentiated cells. The zonation is always recognizable and the apex initiates numerous leaves. The broadening of the meristem is due to the high level of mitotic activity of two opposite regions in the ‘anneau initial’ which takes an elliptical shape and to the peculiar orientation of the mitoses. During this transformation the volumes of the lateral and medullary zones increase while the volume of the axial zone remains almost identical. The long vegetative phase ceases with the homogeneization of the meristematic state of the four superficial layers and with the edification of a prefloral crest.The apex of plants grown under an 8-h photoperiod remains small sized. They never undergo fasciation and reach the prefloral phase very quickly.The meristems of the plants cultivated under 12 h of light daily show an unstable state and sometimes evolve tardily towards fasciation.

Variation de la durée des cycles cellulaires au cours du passage de l'état jeune à l'état adulte dans le méristème caulinaire du Polypodium vulgare

1981 ◽  
Vol 59 (10) ◽  
pp. 1811-1816 ◽  
Author(s):  
Nicole Michaux-Ferrière
Keyword(s):  
Cell Cycle ◽  
Mitotic Activity ◽  
Mitotic Index ◽  
Axial Zone ◽  
Cell Cycles ◽  
Lateral Zone ◽  
A Cell

During the development of Polypodium vulgare L. mitotic indices and duration of cell cycles have been determined for two apical zones of the meristem. In the young state, the mitotic activity of the meristem is high and uniform; the cell cycles of the axial and lateral zones are very similar. At the beginning of the adult state, the axial zone is characterized by a low mitotic index and a cell cycle which is twice that of the lateral zone.

AS1 expression in prostate cancer and its effects on proliferation and invasion of prostate cancer cells

2021 ◽  
pp. 1-9
Author(s):  
Yuxin Li ◽  
Xiaohong Zhuang ◽  
Li Zhuang ◽  
Hongjian Liu
Keyword(s):  
Prostate Cancer ◽  
Cell Proliferation ◽  
Cancer Cells ◽  
Related Protein ◽  
Prostate Cancer Cells ◽  
Blank Group ◽  
Normal Prostate ◽  
Cell Cycles ◽  
Prostate Cells ◽  
Proliferation And Invasion

This paper aimed at investigating AS1 expression in prostate cancer (PCa) and its effects on the proliferation and invasion of prostate cancer cells (PCCs). The prostate tissues and the matched adjacent normal prostate tissues excised and preserved during radical prostatectomy in our hospital were collected. The LncRNA NCK1-AS1 expression was detected. PCa patients were followed up for three years to analyze their prognosis. The correlation of LncRNA NCK1-AS1 expression with clinicopathological features was analyzed. Human normal prostate cells and human PCCs were selected, in which LncRNA NCK1-AS1 expression was tested to screen and then transfect the cells. Cell proliferation, invasion and migration were detected. Cell cycles and apoptosis were analyzed. Compared with the adjacent normal tissues, LncRNA NCK1-AS1 was highly expressed in the prostate cancer tissues. Its expression was remarkably different in those with different stages of TNM and with lymphatic metastasis or not. The prognosis of patients with high LncRNA NCK1-AS1 expression was remarkably poorer than that of those with low expression. Compared with the human normal prostate cells, LncRNA NCK1-AS1 expression in the human PCCs remarkably rose, with the greatest difference in 22Rv1 cells. Compared with the Blank group, cell proliferation and the number of plate cloned cells remarkably reduced in the sh-NCK1-AS1 group. Additionally, in this group, the number of invasive and migratory cells remarkably reduced; the expression of invasion-related protein E-cadherin remarkably rose but that of MMP-2 remarkably reduced; cell cycles were arrested and the expression of cycle-related proteins (CDK4, CDK6, cyclin D1) remarkably reduced; the apoptotic rate and the expression of apoptosis-related protein Bax remarkably rose. LncRNA NCK1-AS1 is highly expressed in PCa, so its down-regulation can inhibit PCCs from proliferating and reduce the number of invasive cells.

Suppression of the rbf null mutants by a de2f1 allele that lacks transactivation domain

Development ◽  
2000 ◽  
Vol 127 (2) ◽  
pp. 367-379 ◽  
Author(s):  
W. Du
Keyword(s):  
Cell Proliferation ◽  
Target Genes ◽  
Suppressor Gene ◽  
Genetic Interactions ◽  
Transactivation Domain ◽  
Transcription Activator ◽  
Drosophila Development ◽  
Mitotic Wave ◽  
E2f Transcription Factors ◽  
Null Mutants

In mammals, a large number of proteins including E2F transcription factors have been shown to interact with the tumor suppressor gene product pRB, but it is not clear to what extend the function of pRB is mediated by E2F. In addition, E2F was shown to mediate both transcription activation and repression; it remains to be tested which function of E2F is critical for normal development. Drosophila homologs of the RB and E2F family of proteins RBF and dE2F1 have been identified. The genetic interactions between rbf and de2f1 were analyzed during Drosophila development, and the results presented here showed that RBF is required at multiple stages of development. Unexpectedly, rbf null mutants can develop until late pupae stage when the activity of dE2F1 is reduced, and can develop into viable adults with normal adult appendages in the presence of a de2f1 mutation that retains the DNA binding domain but lacks the transactivation domain. These results indicate that most, if not all, of the function of RBF during development is mediated through E2F. In turn, the genetic interactions shown here also suggest that dE2F1 functions primarily as a transcription activator rather than a co-repressor of RBF during Drosophila development. Analysis of the expression of an E2F target gene PCNA in eye discs showed that the expression of PCNA is activated by dE2F1 in the second mitotic wave and repressed in the morphogenetic furrow and posterior to the second mitotic wave by RBF. Interestingly, reducing the level of RBF restored the normal pattern of cell proliferation in de2f1 mutant eye discs but not the expression of E2F target genes, suggesting that the coordinated transcription of E2F target genes does not significantly affect the pattern of cell proliferation.

scholarly journals Long-range memory of growth and cycle progression correlates cell cycles in lineage trees

2018 ◽  
Author(s):  
Erika E Kuchen ◽  
Nils Becker ◽  
Nina Claudino ◽  
Thomas Höfer
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Growth ◽  
Mammalian Cell ◽  
Latent Variable ◽  
Cycle Length ◽  
Growth Control ◽  
Minimum Size ◽  
Cell Cycles ◽  
Lineage Trees

Mammalian cell proliferation is controlled by mitogens. However, how proliferation is coordinated with cell growth is poorly understood. Here we show that statistical properties of cell lineage trees – the cell-cycle length correlations within and across generations – reveal how cell growth controls proliferation. Analyzing extended lineage trees with latent-variable models, we find that two antagonistic heritable variables account for the observed cycle-length correlations. Using molecular perturbations of mTOR and MYC we identify these variables as cell size and regulatory license to divide, which are coupled through a minimum-size checkpoint. The checkpoint is relevant only for fast cell cycles, explaining why growth control of mammalian cell proliferation has remained elusive. Thus, correlated fluctuations of the cell cycle encode its regulation.

Potential of rod, sphere and semi-cube shaped gold nanoparticles to induce cytotoxicity and genotoxicity in human blood lymphocytes in vitro

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Mona A.M. Abo-Zeid ◽  
Thomas Liehr ◽  
Amira M. Gamal-Eldeen ◽  
Mahmoud Zawrah ◽  
Mostafa Ali ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Gold Nanoparticles ◽  
Mitotic Activity ◽  
Human Blood ◽  
Human Peripheral Blood ◽  
Human Lymphocytes ◽  
Blood Lymphocytes ◽  
Human Blood Lymphocytes ◽  
Different Shapes

AbstractGold nanoparticles (GNPs) are intended to be used in nanomedicine. Due to nanotechnology innovation GNPs of variable sizes and in different shapes including rods, spheres, cubes, etc., can easily be produced. The aim of the present studies was to evaluate the cyto-and genotoxicity inducible by different shaped GNPs on normal human peripheral blood lymphocytes.Four different shapes of GNPs including big rod GNPs (BR-GNPs, 50 nm), small rod GNPs (SR-GNPs, 30 nm), sphere GNPs (S-GNPs, 15 nm) and semi-cube GNPs (SC-GNPs, 15 nm) were studied. Cultured human blood lymphocytes were treated with different concentrations of these GNPs for 24 h in vitro. Cytotoxicity was evaluated based on the mitotic index (MI), while genotoxicity was studied by an interphase-fluorescence in situ hybridization (I-FISH) assay. The following genes were studied in I-FISH:The lowest concentration of BR-GNPs neither had an effect mitotic activity nor enhanced gain or loss of examined gene signals in a significant manner with I-FSH. Other concentrations of BR-GNPs, SR-GNPs, S-GNPs and SC-GNPs with all concentrations inhibited the mitotic activity of the cells and reduced the cell proliferation highly significantly. The different types of GNPs initiated the duplication ofGNPs at high concentration can reduce the cell proliferation and induce DNA damage. Low concentration of rod-shaped GNPs at 50 nm was safe on human lymphocytes. Further research studies are required to optimize the concentration, shape and size of GNPs before using them in nanomedicine.

scholarly journals DNA CONTENT OF PLACENTAL NUCLEI

1962 ◽  
Vol 13 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Michael Galton
Keyword(s):  
Cell Proliferation ◽  
Dna Synthesis ◽  
Mitotic Activity ◽  
Dna Content ◽  
Reproductive Capacity ◽  
Interphase Nuclei ◽  
Daughter Cells ◽  
Reproductive Ability ◽  
Dna Values ◽  
Rapid Accumulation

The DNA content of individual nuclei in four immature human placentas was determined by microspectrophotometric analysis of Feulgen-stained sections. The absence of mitosis in the syncytiotrophoblast, taken together with the finding of a diploid unimodal distribution, at a time of rapid placental growth, indicated that the syncytiotrophoblast possessed little or no intrinsic reproductive capacity. In contrast, the cytotrophoblast displayed considerable mitotic activity and was found to contain a high proportion of nuclei with DNA values in excess of the diploid amount, corresponding to DNA synthesis in interphase nuclei preparatory to division. From the complementary behavior of the two layers of trophoblast, with respect to evidence of reproductive ability, it is concluded that the rapid accumulation of nuclei in the syncytiotrophoblast, during the early development of the placenta, is accounted for by cell proliferation within the cytotrophoblast followed by alignment and coalescence of some daughter cells in the syncytiotrophoblast.

EFFECTS OF STILBOESTROL ON GROWTH HORMONE SECRETION AND PITUITARY CELL PROLIFERATION IN THE MALE RAT

1971 ◽  
Vol 51 (3) ◽  
pp. 473-481 ◽  
Author(s):  
H. M. LLOYD ◽  
J. D. MEARES ◽  
JOAN JACOBI ◽  
FRANCES J. THOMAS
Keyword(s):  
Growth Hormone ◽  
Cell Proliferation ◽  
Mitotic Activity ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Mean Value ◽  
Pituitary Cell ◽  
Male Rats ◽  
Male Rat ◽  
Serum Growth Hormone

SUMMARY A single 12 mg dose of stilboestrol dipropionate given to 100-day-old male rats resulted in increased pituitary mitotic activity, pituitary weight and serum growth hormone; the latter rose from a mean value of 20 ng/ml to a maximum of 342 ng/ml 9 days later. Serum growth hormone and pituitary mitotic activity then gradually diminished but were still slightly increased on day 28. Serum growth hormone and pituitary weight were significantly correlated during the periods of rapidly rising and of sustained high levels of serum growth hormone. Indices of mitotic activity were correlated with serum growth hormone during the periods of rapidly rising and of falling levels of serum growth hormone.

Further analytical and experimental studies on the shoot apex of Helianthus annuus: variable activity in the central zone

1979 ◽  
Vol 57 (8) ◽  
pp. 971-980 ◽  
Author(s):  
E. L. Davis ◽  
Patricia Rennie ◽  
Taylor A. Steeves
Keyword(s):  
Helianthus Annuus ◽  
Mitotic Activity ◽  
Shoot Apex ◽  
Experimental Studies ◽  
Central Zone ◽  
Peripheral Zone ◽  
Intact Plants ◽  
Cast Doubt ◽  
Young Leaves ◽  
Mitotic Frequency

The cytologically distinctive central zone of the vegetative shoot apex of Helianthus annuus L. cv. Peredovic has a mitotic frequency considerably lower than that of the surrounding peripheral zone in intact plants. Apices excised and grown in culture for 5 days before being supplied with [H3]thymidine reveal a correspondingly low level of DNA synthesis in the central zone when autoradiographed. In similarly cultured apices, mitotic activity in the central zone is less than that recorded for intact plants. Labelling immediately after excision of the apex indicates that the central zone cells are activated by the operation and quiescence returns during the following 5 days. This activation is confirmed by mitotic counts 2 days after excision. The removal of only two young leaves from the apical buds of otherwise intact plants results in a comparable stimulation of mitotic activity in the central zone. These observations cast doubt upon the significance of mitotic activity in living shoot apices when these have been exposed for observation by removal of leaves. They also raise questions about the validity of labelling techniques which involve the partial dissection of the shoot apex.

scholarly journals Upregulated microRNA-106a Promotes Porcine Preadipocyte Proliferation and Differentiation by Targeting Different Genes

Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 805 ◽  
Author(s):  
Kuilong Huang ◽  
Xin’e Shi ◽  
Jie Wang ◽  
Ying Yao ◽  
Ying Peng ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Lipid Droplets ◽  
Luciferase Reporter ◽  
Cell Cycles ◽  
Lipogenic Genes ◽  
Proliferation And Differentiation ◽  
Luciferase Reporter Vector ◽  
Membrane Bound ◽  
Porcine Adipocytes ◽  
Oil Red O

Adipose tissue is one of the main organs for the energy storage and supply of organisms. Adipose deposition and metabolism are controlled by a cascade of transcription factors and epigenetic regulatory mechanisms. Previous studies have also shown that miR-106a plays a considerable role in the development of organisms. The regulatory mechanism of miR-106a on porcine preadipocytes is still not clear. In this study, preadipocytes were isolated from the neck subcutaneous deposits of 3–5-day old Chinese native Guanzhong black pigs using 5-ethynyl-20-deoxyuridine (EdU) staining and a CCK-8 assay to detect the number of proliferous cells and real-time qPCR (RT-qPCR) and western blot analysis to detect gene expression, as well as Oil Red O and BODIPY staining dye lipid droplets and flow cytometry (FCM) to detect cell cycles. We also used the double luciferase method to detect the relative luciferase activities. Upregulated miR-106a increased the number of proliferous cells and enhanced the expression of cell proliferation-related genes in porcine adipocytes. The double luciferase reporter vector confirmed that p21 was a target gene of miR-106a in the cell proliferation phase. miR-106a upregulation increased the number of lipid droplets and the expression of lipogenic genes and directly targeted BMP and activin membrane-bound inhibitor (BAMBI) in the process of differentiation. Our results indicated that miR-106a promotes porcine preadipocyte proliferation and differentiation by targeting p21 and BAMBI.

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