Long duration of mitosis and consequences for the cell cycle concept, as seen in the isthmal cells of the mouse pyloric antrum. I. Identification of early and late steps of mitosis

Osteoblast-osteoclast interaction plays an important role in the bone remodeling. During long duration space flight, astronauts undergo serious bone loss mainly due to the disruption of equivalence between bone formation and bone resorption. Osteoclast precursors often operate under the control of osteoblasts. However, here we show that the osteoclast precursors could in turn influence osteoblasts. RAW264.7 cells, the murine osteoclast precursors, were treated in the simulated weightlessness produced by a Random Positioning Machine (RPM). After 72 h, conditioned mediums (CM) by the RAW264.7 cells from RPM (RCM) or static control (CCM) were collected and were used to culture osteoblastic-like MC3T3-E1 cells. The results showed that the RCM culture inhibited cell viability and slightly altered cell cycle, but the morphology of the MC3T3-E1 cells was not changed by RCM compared to that of CCM. Furthermore, the intracellular ALP level, NO release and expression of osteoblastic marker genes were all down-regulated by RCM culture. These results suggest that osteoclast precursors subjected to RPM exert negative regulation on osteoblasts.

Download Full-text

DURATION OF MITOTIC CYCLE IN BRAIN CELLS OF THE MOSQUITO, AEDES DORSALIS

Canadian Journal of Genetics and Cytology ◽

10.1139/g69-080 ◽

1969 ◽

Vol 11 (3) ◽

pp. 673-676 ◽

Cited By ~ 5

Author(s):

Asit B. Mukherjee ◽

Don M. Rees

Keyword(s):

Cell Cycle ◽

High Resolution ◽

Mitotic Cycle ◽

Brain Cells ◽

Duration Of Mitosis ◽

High Resolution Autoradiography

Duration of the mitotic cycle and its various phases in the dividing brain cells of Aedes dorsalis larvae has been determined by high-resolution autoradiography. The length of the cell cycle is 10 hours. The duration of G1 is about 1 hour and 15 minutes, DNA synthetic period (S) is approximately 7 hours, G2 is 1 hour and the duration of mitosis (M) is about 45 minutes.

Download Full-text

The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast

The Journal of Cell Biology ◽

10.1083/jcb.201609114 ◽

2017 ◽

Vol 216 (11) ◽

pp. 3463-3470 ◽

Cited By ~ 29

Author(s):

Ricardo M. Leitao ◽

Douglas R. Kellogg

Keyword(s):

Cell Cycle ◽

Cell Size ◽

Daughter Cell ◽

Slow Growth ◽

Budding Yeast ◽

Size Control ◽

G1 Phase ◽

Large Reduction ◽

Duration Of Mitosis ◽

Cell Cycle Entry

The size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast.

Download Full-text

The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast

10.1101/080648 ◽

2016 ◽

Cited By ~ 1

Author(s):

Ricardo M. Leitao ◽

Douglas R. Kellogg

Keyword(s):

Cell Cycle ◽

Cell Size ◽

Daughter Cell ◽

Slow Growth ◽

Budding Yeast ◽

Size Control ◽

G1 Phase ◽

Large Reduction ◽

Duration Of Mitosis ◽

Cell Cycle Entry

AbstractThe size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast.

Download Full-text

Chronological changes in the cell cycle of chick neuroepithelial cells

Development ◽

10.1242/dev.29.3.745 ◽

1973 ◽

Vol 29 (3) ◽

pp. 745-751

Author(s):

D. B. Wilson

Keyword(s):

Cell Cycle ◽

Optic Tectum ◽

Generation Time ◽

Marked Change ◽

Chick Embryos ◽

Duration Of Mitosis ◽

Neuroepithelial Cells ◽

S Period

Radioautographic data obtained from a total of 103 chick embryos injected with [3H]thymidine suggest that the generation time of neuroepithelial cells in dorsolateral regions of the optic tectum increases from approximately 8 h at 3 days of incubation to 15 h at 6 days of incubation. The most marked change occurs between the 4th and 5th day, when the generation time increases from 9 to 13 h, respectively. Between the 3rd and 6th day of incubation the length of the DNA-synthetic (S) period and of the premitotic (G2) period remains fairly constant; however, the duration of mitosis (M) and of the postmitotic (G1) period appears to be prolonged.

Download Full-text

Positive Feedback Keeps Duration of Mitosis Temporally Insulated from Upstream Cell-Cycle Events

Molecular Cell ◽

10.1016/j.molcel.2016.09.018 ◽

2016 ◽

Vol 64 (2) ◽

pp. 362-375 ◽

Cited By ~ 38

Author(s):

Ana Rita Araujo ◽

Lendert Gelens ◽

Rahuman S.M. Sheriff ◽

Silvia D.M. Santos

Keyword(s):

Cell Cycle ◽

Positive Feedback ◽

Duration Of Mitosis

Download Full-text

The LDE-Type Flare Occurrence (1969-1993)

International Astronomical Union Colloquium ◽

10.1017/s0252921100025458 ◽

1994 ◽

Vol 144 ◽

pp. 279-282

Author(s):

A. Antalová

Keyword(s):

Time Series ◽

Fourier Analysis ◽

Sunspot Cycle ◽

List Type ◽

Type Number ◽

Solar Cycles ◽

Type Iv ◽

Long Duration ◽

Cycle Maximum ◽

Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

Download Full-text

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079747 ◽

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.

Download Full-text

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053280 ◽

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.

Download Full-text