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.

Neurotrophic control of events in injured forelimbs of larval urodeles

Development ◽  
1982 ◽  
Vol 69 (1) ◽  
pp. 183-192
Author(s):  
Anthony L. Mescher
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Mitotic Activity ◽  
Mitotic Index ◽  
Elevated Level ◽  
Labelling Index ◽  
Neurotrophic Control ◽  
Epimorphic Regeneration ◽  
Baseline Levels

Denervated forelimbs and contralateral innervated forelimbs of Ambystoma larvae were injured internally distal to the elbow by compression with watchmaker's forceps. Innervated controls completely repaired the crush injury within one week; denervated limbs failed to repair the injury and exhibited varying degrees of limb regression. Histological examination revealed that the process of tissue dedifferentiation initiated by injury was more extensive in denervated, regressing limbs than in controls. In innervated limbs, both the DNA labelling index and the mitotic index peaked approximately 4–6 days after the injury and returned to baseline levels by 10 days. In denervated limbs, the DNA labelling index also increased and remained at an elevated level for at least 2 weeks after the injury, but significant mitotic activity was not observed. The data indicate that intact nerves are not needed for cellular dedifferentiation, cell cycle re-entry, and DNA synthesis in injured limbs, but are required for the cells to proliferate and repair the injury. These results are discussed together with those of similar experiments on the role of nerves during the initiation of epimorphic regeneration in amputated limbs.

scholarly journals A molecular marker for centriole maturation in the mammalian cell cycle.

1995 ◽  
Vol 130 (4) ◽  
pp. 919-927 ◽  
Author(s):  
B M Lange ◽  
K Gull
Keyword(s):  
Cell Cycle ◽  
Molecular Marker ◽  
Specific Cell ◽  
Cell Cycles ◽  
Functional Maturation ◽  
Ability To Act ◽  
Molecular Events ◽  
Mammalian Cell Cycle ◽  
A Cell ◽  
First Time

The centriole pair in animals shows duplication and structural maturation at specific cell cycle points. In G1, a cell has two centrioles. One of the centrioles is mature and was generated at least two cell cycles ago. The other centriole was produced in the previous cell cycle and is immature. Both centrioles then nucleate one procentriole each which subsequently elongate to full-length centrioles, usually in S or G2 phase. However, the point in the cell cycle at which maturation of the immature centriole occurs is open to question. Furthermore, the molecular events underlying this process are entirely unknown. Here, using monoclonal and polyclonal antibody approaches, we describe for the first time a molecular marker which localizes exclusively to one centriole of the centriolar pair and provides biochemical evidence that the two centrioles are different. Moreover, this 96-kD protein, which we name Cenexin (derived from the Latin, senex for "old man," and Cenexin for centriole) defines very precisely the mature centriole of a pair and is acquired by the immature centriole at the G2/M transition in prophase. Thus the acquisition of Cenexin marks the functional maturation of the centriole and may indicate a change in centriolar potential such as its ability to act as a basal body for axoneme development or as a congregating site for microtubule-organizing material.

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.

scholarly journals Changes in the number and size of nucleoli of Chara vulgaris L. antheridial filament cells during the period preceding light-induced re-initiation of cell divisions following a mitodepressive effect of darkness

2014 ◽  
Vol 68 (4) ◽  
pp. 251-254
Author(s):  
Maria Kwiatkowska ◽  
Ewa Papiernik
Keyword(s):  
Cell Cycle ◽  
Developmental Stage ◽  
Mitotic Activity ◽  
Silver Staining ◽  
Staining Method ◽  
Chara Vulgaris ◽  
Cell Divisions ◽  
A Cell ◽  
Silver Staining Method

The changes in number and size of nucleoli of <em>Chara vulgaris</em> antheridial filament cells were monitored with the use of Howell and Black's silver staining method. After a 3-day mitodepressive treatment with darkness the cells were exposed to light which reactivated mitotic activity after 18-20 hours. Eight-celled antheridial filaments were observed. In the period preceding light-induced re-initiation of mitoses a gradual reconstruction of the number and size of nucleoli characteristic of control, as well as their total area per nucleus appeared. The obtained results indicate that one of the important conditions for a cell to be able to divide is accumulation of nucleolus components characteristic of a given developmental stage and this controls nucleologenesis of the subsequent cell cycle.

scholarly journals The evaluation of proliferation ability of cardiomyocytes in heart failure

2021 ◽  
Vol 271 ◽  
pp. 03064
Author(s):  
Mengzi Gao
Keyword(s):  
Heart Failure ◽  
Cell Cycle ◽  
Myocardial Dysfunction ◽  
Left Ventricular ◽  
Clinical Syndrome ◽  
Rna Seq ◽  
Cell Cycles ◽  
A Cell ◽  
Proliferation Ability ◽  
Heat Failure

The proliferation ability of cardiomyocytes is always under a controversial situation, especially under some stress condition such as heart failure disease and external damages. Heat failure (HF) is a complex clinical syndrome that results from left ventricular myocardial dysfunction and contributes to dyspnea, fatigue and fluid retention. The proliferation ability is related to the cell cycles and lot of cell-cycle related genes are involved in the evaluation of proliferation ability of cardiomyocytes. RNA-seq is a quite common technique in evaluate the transcription expression pattern of genes in many studies. Here in our article we analyzed the existing RNA-seq dataset to evaluate the mRNA expression level of several genes which can be indicators of the activity of cell cycles. We found that the cyclin D2 which is a cell cycle activator is upregulated in dilated cardiomyopathy (DCM) disease, indicating that the proliferation ability may be higher in DCM heart. The results throw light on the proliferation research of adult cardiomyocytes.

Early determination in the C. elegans embryo: a gene, cib-1, required to specify a set of stem-cell-like blastomeres

Development ◽  
1990 ◽  
Vol 108 (1) ◽  
pp. 107-119 ◽  
Author(s):  
R. Schnabel ◽  
H. Schnabel
Keyword(s):  
Cell Cycle ◽  
Decision Making ◽  
Stem Cell ◽  
Early Embryo ◽  
Cell Cycles ◽  
C Elegans ◽  
Lethal Mutations ◽  
A Cell ◽  
Early Decision ◽  
P Cells

The early somatic blastomeres founding the tissues in the C. elegans embryo are derived in a stem-cell-like lineage from the P cells. We have isolated maternal effect lethal mutations defining the gene cib-1 in which the P cells, P1-P3, skip a cell cycle and acquire the fates of only their somatic daughters. Therefore, the cib-1 gene is required for the specification of the stem-cell-like fate of these cells. The analysis of the development of these mutants suggests that the clock controlling the cell cycles in the early embryo is directly coupled to the fate of a cell and that there must be another developmental clock that activates the determinative inventory for the early decision-making.

Plastochrone, cycle cellulaire et teneurs en ADN nucléaire du méristème caulinaire de plants de Chrysanthemum segetum soumis à deux conditions lumineuses différentes, sous une photopériode de 16 heures

1990 ◽  
Vol 68 (11) ◽  
pp. 2389-2397 ◽  
Author(s):  
Arlette Nougarède ◽  
Maria Nicola Di Michele ◽  
Pierre Rondet ◽  
Robert Saint-Côme
Keyword(s):  
Cell Cycle ◽  
Doubling Time ◽  
Nuclear Dna ◽  
Cycle Duration ◽  
Axial Zone ◽  
Lateral Zone ◽  
Cell Doubling Time ◽  
Photon Fluence ◽  
The Mean ◽  
Chrysanthemum Segetum

Chrysanthemum segetum plants were grown from seeds under a 16-h photoperiod, at two different photon fluence rates (70 or 200 μmol m−2 s−1. At 200 μmol m−2 s−1, by comparison with 70 μmol m−2 s−1, phyllotaxy was not modified, but the plastochron decreased and the apical diameter increased by extension of the axial zone. The mean cell doubling time decreased 36.2% in the lateral zone, 29% in the axial zone, and only 13% in the rib meristem. In contrast, mitosis duration was constant. Under both light conditions, nuclei with a DNA content within the limits of the 2C range were always predominant, which means that the G1 phase of the cell cycle was the longest. At 200 μmol m−2 s−1, the shortening of the mean cell doubling time is accompanied by a reduction of the percentage of nuclei with DNA levels within the limits of the 2C range. The decrease of the latter was the most important in the axial zone and the least important in the rib meristem, showing that control of cell proliferation was obtained by means of the G1 phase of the cell cycle. Key words: Chrysanthemum segetum, cell cycle, duration of mitosis, plastochron, nuclear DNA levels, zonation.

scholarly journals Cyclin Cln3p Links G1 Progression to Hyphal and Pseudohyphal Development in Candida albicans

2005 ◽  
Vol 4 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Catherine Bachewich ◽  
Malcolm Whiteway
Keyword(s):  
Cell Cycle ◽  
Candida Albicans ◽  
Critical Role ◽  
Growth Conditions ◽  
Yeast Cells ◽  
Independent Manner ◽  
Cell Cycles ◽  
Environmental Controls ◽  
A Cell ◽  
Synthetically Lethal

ABSTRACT G1 cyclins coordinate environmental conditions with growth and differentiation in many organisms. In the pathogen Candida albicans, differentiation of hyphae is induced by environmental cues but in a cell cycle-independent manner. Intriguingly, repressing the G1 cyclin Cln3p under yeast growth conditions caused yeast cells to arrest in G1, increase in size, and then develop into hyphae and pseudohyphae, which subsequently resumed the cell cycle. Differentiation was dependent on Efg1p, Cph1p, and Ras1p, but absence of Ras1p was also synthetically lethal with repression of CLN3. In contrast, repressing CLN3 in environment-induced hyphae did not inhibit growth or the cell cycle, suggesting that yeast and hyphal cell cycles may be regulated differently. Therefore, absence of a G1 cyclin can activate developmental pathways in C. albicans and uncouple differentiation from the normal environmental controls. The data suggest that the G1 phase of the cell cycle may therefore play a critical role in regulating hyphal and pseudohyphal development in C. albicans.

scholarly journals CONDITIONAL MUTANTS IN CHLAMYDOMONAS REINHARDTII BLOCKED IN THE VEGETATIVE CELL CYCLE

1973 ◽  
Vol 57 (3) ◽  
pp. 760-772 ◽  
Author(s):  
Stephen H. Howell ◽  
Jay A. Naliboff
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Chlamydomonas Reinhardtii ◽  
Simple Technique ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
General Applicability ◽  
Cell Cycles ◽  
Point Analysis ◽  
A Cell

Conditional "cycle-blocked" (cb) mutants of Chlamydomonas reinhardtii have been detected and isolated. These mutants exhibit normal vegetative growth at permissive temperature but are unable to complete a cell cycle (or a specified number of cell cycles) at restrictive temperature. A simple technique has been devised to determine the cell cycle stage in each mutant when the defective gene product, which ultimately affects cell division, completes its function. This stage is called the "block point", and is determined by scoring the residual cell division in an exponentially growing population after shift to temperature restrictive conditions. In the cb mutants isolated so far, block points representing many stages throughout the cell cycle have been found. Two categories of cb mutants are described here: one set which prevents the subsequent cell division when the cell encounters the block point after a shift to restrictive temperature, and another set which permits an additional round of cell division after the block point is encountered. The general applicability of block point analysis to other cell systems is presented.

Characterization of the unusually rapid cell cycles during rat gastrulation

Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 873-883 ◽  
Author(s):  
A. Mac Auley ◽  
Z. Werb ◽  
P.E. Mirkes
Keyword(s):  
Cell Cycle ◽  
Cycle Time ◽  
Mammalian Cells ◽  
Primitive Streak ◽  
Cycle Duration ◽  
Embryonic Cells ◽  
Cell Cycle Time ◽  
Cell Cycles ◽  
A Cell ◽  
Cycle Regulation

The onset of gastrulation in rodents is associated with the start of differentiation within the embryo proper and a dramatic increase in the rate of growth and proliferation. We have determined the duration of the cell cycle for mesodermal and ectodermal cells of rat embryos during gastrulation (days 8.5 to 9.5 of gestation) using a stathmokinetic analysis. These embryonic cells are the most rapidly dividing mammalian cells yet described. Most cells of the ectoderm and mesoderm had a cell cycle time of 7 to 7.5 hours, but the cells of the primitive streak divided every 3 to 3.5 hours. Total cell cycle time was reduced by shortening S and G2, as well as G1, in contrast to cells later in development, when cell cycle duration is modulated largely by varying the length of G1. In the ectoderm and mesoderm, G1 was 1.5 to 2 hours, S was 3.5 to 4 hours, and G2 was 30 to 40 minutes. G1, S and G2 were shortened even further in the cells of the primitive streak: G1 was less than 30 minutes, S was 2 to 2.75 hours, and G2 was less than 20 minutes. Thus, progress of cells through all phases of the cell cycle is extensively modified during rodent embryogenesis. Specifically, the increased growth rate during gastrulation is associated with radical changes in cell cycle structure and duration. Further, the commitment of cells to become mesoderm and endoderm by entering the primitive streak is associated with expression of a very short cell cycle during transit of the primitive streak, such that developmental decisions determining germ layer fate are reflected in differences in cell cycle regulation.

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