The Chromatin Extrusion Phenomenon in Amoeba proteus Cell Cycle

2019 ◽  
Vol 67 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Andrew V. Goodkov ◽  
Mariia A. Berdieva ◽  
Yuliya I. Podlipaeva ◽  
Sergei Yu. Demin
Keyword(s):  
Cell Cycle ◽  
Amoeba Proteus

An autoradiographical study of amino acid and nucleoside incorporation during the cell cycle of Amoeba proteus

1981 ◽  
Vol 51 (1) ◽  
pp. 219-228
Author(s):  
K.I. Mills ◽  
L.G. Bell
Keyword(s):  
Cell Cycle ◽  
Amino Acids ◽  
Amino Acid ◽  
Rna Synthesis ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Macromolecular Synthesis ◽  
Future Studies ◽  
Specific Proteins

The incorporation of tritiated thymidine, uridine and leucine, into the acid-precipitable material of DNA. RNA and proteins, respectively, was studied by autoradiography throughout the cell cycle of Amoeba proteus. DNA synthesis occupied the first 17 h of the cycle (57 h long) and 2 peaks between 0.5 and 9.13 h accounted for the majority of the thymidine incorporation. RNA synthesis was represented by a series of peak uridine grain counts, the 3 major peaks occurring at 10, 26–27 and 47–48 h. The incorporation of leucine also followed a pattern of peaks and dips, the main peaks occurring 1–2 h after the major increases in uridine incorporation. The fraction of label present over the nucleus decreased during the cell cycle, and this was probably due to a lowered incorporation of the leucine label by proteins synthesized in the cytoplasm and destined to become nuclear proteins. The incorporation patterns of 6 amino acids (arginine, aspartic acid, leucine, lysine, serine and valine) were studied individually during 3 periods of the cell cycle: 0-10 h (S phase); 20–30 h (early G2); and 40–50 h (mid-late G2). Variations in the intensity and timings of the incorporation maxima of the amino acids were observed, although the timings of increased grain counts of some of the amino acids frequently coincided. “Unique” incorporation peaks (i.e. only observed in one of the amino acids studied) possibly indicate the synthesis of phase-specific proteins. The amino acid and nucleoside incorporation profiles presented in this paper will enable the results obtained from future studies on amoebae to be related to the macromolecular synthesis patterns.

Optical tomography analysis of Amoeba proteus chromatin organization at various cell cycle stages

2016 ◽  
Vol 10 (1) ◽  
pp. 84-94 ◽  
Author(s):  
S. Yu. Demin ◽  
M. A. Berdieva ◽  
Yu. I. Podlipaeva ◽  
A. L. Yudin ◽  
A. V. Goodkov
Keyword(s):  
Cell Cycle ◽  
Optical Tomography ◽  
Amoeba Proteus ◽  
Chromatin Organization ◽  
Tomography Analysis

The Synthesis of DNA Through the Cell Cycle of Amoeba Proteus

1968 ◽  
Vol 3 (4) ◽  
pp. 483-491
Author(s):  
M. J. ORD
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Amoeba Proteus ◽  
Pulse Labelling ◽  
Two Peaks ◽  
Second Peak

DNA synthesis has been investigated in Amoeba proteus by pulse-labelling cells of known age with [3H]thymidine. Ninety per cent of the DNA so labelled was synthesized during the first quarter of the cell cycle. Synthesis was in two peaks: the first occurring between 0.5 and 4 h after division and the second at about 10 h. All cells labelled at both peaks. The authenticity of the second peak was proved statistically. Considerable variation was observed among amoebae of similar age. In experiments in which daughter amoebae underwent different treatments, differences in the rates of incorporation of [3H]thymidine due to differences in the nutrition of the cells were found to be a predominant cause of variation. Heavy feeding reduced labelling; starvation increased labelling while at the same time reducing variability.

Generation times and reproductive rates of Amoeba proteus (Leidy) as influenced by temperature and food concentration

1980 ◽  
Vol 58 (4) ◽  
pp. 543-548 ◽  
Author(s):  
Andrew Rogerson
Keyword(s):  
Cell Cycle ◽  
Marked Effect ◽  
Tetrahymena Pyriformis ◽  
Food Concentration ◽  
Amoeba Proteus ◽  
Prey Concentration ◽  
Generation Times ◽  
Reproductive Rates

Temperature was found to have a marked effect upon the generation times of Amoeba proteus when cultured with Tetrahymena pyriformis at 20, 15, and 10 °C. The length of the cell cycle varied from 44 h at 20 °C to 2926 h at 10 °C. For each temperature studied, generation times followed a U-shaped distribution where the greatest division potential was determined by the prey concentration. Optimum reproductive rates were achieved at lower food levels as temperature was decreased. The results are discussed in the context of the available published literature.

Studies on changes in the nuclear helices of Amoeba proteus during the cell cycle

1976 ◽  
Vol 20 (2) ◽  
pp. 273-287
Author(s):  
I. Minassian ◽  
L.G. Bell
Keyword(s):  
Cell Cycle ◽  
Fine Structure ◽  
Cell Population ◽  
Amoeba Proteus ◽  
Ultrastructural Changes ◽  
Growing Cell

The fine structure of the nuclei of synchronously growing cell population of Amoeba proteus was studied at I-h intervals during the interphase. This study showed that the nuclear helices undergo increases in their number at certain stages during interphase. These changes were found to correlate with ultrastructural changes occurring in the nucleoli.

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.

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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