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Results for “polyploidization”

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PubMed2000

Different responses of polyploidized V79 cells after removal of two drugs, demecolcine and K-252a.

To examine whether or not cells polyploidized by different mechanisms behave in a different manner after drug removal, V79 Chinese hamster cells were assessed by flow cytometry (FCM) after their polyploidization by demecolcine and K-252a, inhibitors of spindle-fiber formation and protein kinase, respectively. Cell cycle analysis of DNA histograms of V79 cells before and after the drug release was performed. With both drugs, the ploidy of V79 cells increased just after the drug removal and was maintained for a week. A difference was evident 10 days after the release. Tetraploid cells were the main population from 10 to 18 days after the release of K-252a, but not demecolcine. Cell cycle parameters were almost the same in pseudo diploid and tetraploid V79 cells, except for the tetraploid S phase which was 2h longer.

Animals↗
PubMed1992

Effects of butyrate on cell cycle progression and polyploidization of various types of mammalian cells.

We studied the effect of butyrate on cell cycle progression and polyploidization in three fibroblast (rat 3Y1, human IMR-90, and human embryo lung HEL) and two epithelial (human embryo kidney HEK and monkey kidney BSC-1) cells. In these cells, except for 3Y1, G1 arrest with butyrate was incomplete, and the production of tetraploid cells was detectable in the presence of butyrate. G2 arrest with butyrate was also incomplete in HEL and BSC-1 cells, and the number of HEL cells increased in the presence of butyrate. On the contrary, most BSC-1 cells that divided in the presence of butyrate were unstable and the number of attached cells decreased. These results indicate that the effect of butyrate on cell cycle progression varies with the cell type and that polyploidization can be induced by a single treatment with butyrate.

Animals↗
PubMedDate not supplied

Aneuploid and polyploid cellular DNA heterogeneity in insect cell material of diptera species analyzed by flow cytometry.

Flow cytometric 1-parameter DNA analysis and 2-parameter DNA/protein analysis have been performed with cell material of the diptera species Chironomus thummi, Drosophila melanogaster, Calliphora vicina and Musca domestica using an impulse cytophotometer with a new quartz objective, that was especially manufactured for cytofluorometric investigations. The occurrence of heterogenous cell populations with aneuploid and polyploid DNA content within the cell material of different developmental stages of diptera species have been determined, whereby in larvae polyploid cell populations and in imagos aneuploid cell populations predominate. Partially separation of 2 C cells from other cell populations with higher DNA content can be done by Ficoll-Hypaque centrifugation as demonstrated with cell material from Chironomus larvae. For flow cytometric DNA analysis of insect cell material a simple and rapid cell preparation and staining technique is presented by using the DNA-specific fluorochrome DAPI in combination with the protein fluorochrome sulforhodamine 101. Employment of flow cytometry in diptera genetics might be a new tool for cytological and cytogenetic investigations as shown with the classical genetic objects Chironomus and Drosophila.

Aneuploidy↗
PubMed1986

Polyploid cells in blastocysts and early fetuses from Australian Merino sheep.

Cytogenetic examination was made of 103 13-14-day-old blastocysts and 116 24-32-day-old fetuses from untreated and androstenedione-7-HSA-immunized Merino ewes. There were no differences in the chromosome composition of blastocysts or fetuses from treated or untreated ewes and so the data were combined. At Days 13-14 a 1N/2N mosaic and a 2N - 1/2N/4N mosaic embryo were observed. In addition, 52 of the blastocysts were 2N/4N mosaics, with 8 of these also containing 8N cells, and one blastocyst was a 2N/8N mosaic. No aneuploid fetuses were observed, but 80 of the 116 fetuses contained polyploid cells, including 4N, 6N and 8N cells. The polyploid cells observed in the blastocysts and fetuses should not be considered as abnormal cells as they appear to be a normal part of the developmental processes leading to trophoblast formation and fetal differentiation.

Animals↗
PubMedDate not supplied

Human megakaryocyte polyploidization is associated with a decrease in GPIIIA expression.

Megakaryocytes are platelet forming cells and are characterized by polyploidization, a phenomenon by which nuclear division occurs without corresponding cytoplasmic separation. Among the markers allowing to identify megakaryocytes, glycoprotein (GP) IIIa with GPIb and GPIIb are the most important. Using GPIIIa as a marker to recognize megakaryocytes in the bone marrow, we have estimated GPIIIa expression by flow cytometry in megakaryocyte populations from normal individuals and from patients with chronic myelogenous leukemia, immune thrombocytopenic purpura or polycythemia vera. We showed that the expression of GPIIIa is decreasing during megakaryocyte polyploidization in normal and pathological situations.

Antigens, CD↗
PubMed2000

[Induction of polyploid in the Pacific abalone by caffeine-heat shock treatments].

Polyploid of Pacific abalone, Haliotis discus hannai Ino, was induced by blocking Polar body I with caffeine-heat shock treatments. Fertilized eggs were treated with caffeine concentrations at: 2.5 mmol/L, 5 mmol/L and 10 mmol/L; heat shock temperatures at 24 degrees C, 26 degrees C, 28 degrees C, lasting for 10 min to 30 min, total 5 periods of time, beginning at 10 min post-fertilization. Both fertilizing and incubating at 21 degrees C sea water. The results of studies showed that the effective procedure for inducing triploid appeared to be 5 mmol/L and 10 mmol/L Caffeine concentration, heat shock temperature 26 degrees C, duration 10 min to 15 min, all beginning at 10 min after insemination. The percentage of triploid was 64.6%-77.8%, Comprehensive efficiency index of polyploid induction was 0.57-0.61. Under the condition of 5 mmol/L caffeine concentration and the temperature 26 degrees C for 30 min duration at 10 min post-fertilization, 2.8%-3.6% tetraploid embryos could be produced.

Animals↗
PubMedDate not supplied

[The induction of hepatocyte polyploidization in rats of various ages by ionizing irradiation with different LETs].

A decrease in the effectiveness of neutron-irradiation with respect to fusion of nonproliferating hepatocytes of animals with age was shown by the method of flow cytometry. There was an inverse relationship between the effectiveness of induction of nonproliferating hepatocytes fusion and neutron energy. The process of hepatocyte fusion induced by neutrons was inhibited by uranyl acetate. No age-dependent changes were noted in the induction of polyploidization of proliferating hepatocytes by sparsely ionizing radiation. A hypothesis is proposed concerning a membrane nature of the target responsible for hepatocyte polyploidization induced by densely ionizing radiation.

Aging↗
PubMedDate not supplied

[Polyploidization of rat hepatocytes due to cell fusion caused by radiations of different LET].

The method of flow cytometry was used to study polyploidization of hepatocytes following X-, gamma-, and neutron-irradiation. Ionizing radiation was shown to induce cell polyploidization by two different ways: (1) cells and nuclei fusion, and (2) restriction of mitosis after DNA replication. RBE of 14 MeV neutrons with respect to fusion was about 5.10(3). With neutron irradiation, the sensitivity of cells by fusion was not lower than that by chromosome mutations.

Animals↗
PubMedDate not supplied

[Polyploidization of cardiac myocytes as a programmed event of ontogenesis].

The pieces of ventricles of newborn rats, which consist of diploid myocytes in more than 95%, were transplanted under the renal capsule of a syngeneic adult rat. Within 35 days the transplants contained 40 to 60% of the cells with the double or even greater DNA content in the mononuclear and binuclear classes. The composition of the classes was similar unlike the number of the cells of a certain class in the transplant and in the heart of a 35 day old rat. A conclusion has been drawn that the polyploidization is programmed and the realization of this programme depends on the growth, work, and other factors but is expressed even at their minimal action in the transplant. The growth of the transplanted myocytes was weaker than in the heart. It is supposed that, unlike the polyploidization, the growth of the myocytes outside the cycle is, predominantly, functional-dependent.

Animals↗
PubMed1986

[Analysis of the polyploidization kinetics of the parenchymal cells in the rat liver].

Methodological approaches to kinetics of cell polyploidization in the rat liver parenchyma are discussed. Different ways of hepatocyte polyploidization in the course of postnatal liver growth have been assessed. The intensities of hepatocyte transitions from one ploidy class to another were determined. On the basis of literary experimental data the following is summarized: With the increase in the animal age, there is a decrease in hepatocyte transition from one ploidy class to and ther; in young animals the intensity of formation of tetraploid hepatocytes through the stage of binuclear cells (2c----2c X 2----4c) is 0.39-0.55 within two weeks, the intensity of direct transitions (2c----4c) being 0.00-0.19 within the same time. The intensity of entering to DNA synthesis is reduced with the increase in hepatocyte ploidy levels; in this case the coefficient of the reducing of mitotic activity is calculated as 0.10-0.22, and 0.01-0.05 for 4c- and 8c-hepatocytes, resp. The factors stimulating proliferation in the liver increase the intensity of the direct cell transition (2c----4c) by several times which can exceed the intensity of transition through the binuclear cell stage.

Aging↗
PubMedDate not supplied

Growth arrest and polyploidization induced by metahalone microtubule inhibitors on rat glioma cells in culture.

Two pyrimidine analogs (metahalones) NY 3163, NY 3170 have been tested for their effects on the growth of rat glioma cells in monolayer and in spheroid culture. Both substances have earlier been found to inhibit the microtubule system in malignant cells. In glioma cells, arrest of mitosis was accompanied by repeated cycles of DNA synthesis, leading to different levels of polyploidization up to 16 and 32 ploid cells. The effect was not reversible through a culture period of 4 days. Reduced ability of directional migration of cells on a plastic surface was seen for 16 days after exposure. The reaction to microtubule inhibitors seems to differ depending on the type of tumour cells, where some malignant cells have earlier been reported to escape mitotic arrest and proceed to the next G1 phase, in contrast to the present glioma cells which undergo polyploidization.

Animals↗
PubMed1978

Cell kinetics of mouse urinary bladder epithelium. III. A histologic and ultrastructural study of bladder epithelium during regeneration after a single dose of cyclophosphamide, with special reference to the mechanism by which polyploid cells are formed.

In order to see whether the polyploid cells lining the mouse urinary bladder are formed by nuclear fusion, such epithelium was studied under the light and electron microscope forty-eight hours after an injection of cyclophosphamide when the bladder epithelium regenerates with rapid formation of many diploid, tetraploid and octoploid cells. The probability of seing fusion, if it occurs, ought then to be high. Serial sections of many specimens from four mice revealed no signs of fusion. Thus we found no support for the theory that polyploid cells are formed by nuclear fusion.

Animals↗
PubMed1984

Induction of polyploid nuclei in the plasmodium of Physarum polycephalum by platinum antitumor compounds.

The intranuclear mitosis of the plasmodial nuclei of myxomycetes permits the observation of defects in chromosomal repartition which would probably be lethal in other eukaryotic cells with open mitosis. We found that antitumoral platinum-amine compounds perturbed late mitotic events and induced the formation of giant nuclei which were polyploid in plasmodia of Physarum polycephalum. Using 26 platinum-amine complexes, we have shown that all antitumoral compounds induced the formation of polyploid nuclei for drug concentrations at least three times lower than the amount necessary to block the overall plasmodial growth, whereas platinum compounds without antitumor activity did not behave this way. DNA replication appeared to be quantitatively normal during formation of giant nuclei by antitumoral compounds. These observations suggest that platinum-amine compounds exert their antitumor activity by interfering with mitosis rather than by a gross inhibition of DNA synthesis.

Cell Nucleolus↗
PubMed1983

[Effect of polyploidization on the anchorage-independent multiplication of transformed cells].

Three nearhexaploid sublines were obtained from hypotriploid mouse L cells by means of colcemid treatment. When cultivated on solid substratum, all of them did not differ from the parental line either in doubling time or in cloning efficiency. The ability of polyploid cell variants to be initiated for proliferation in a semi-solid medium was equal to that of hypotriploid cells, while the average diameter of colonies formed by hexaploid cells in methyl cellulose turned out to be significantly smaller than the size of colonies of parental cells. The inhibition of growth in the semi-solid medium may reflect partial normalization of the transformed phenotype of polyploid L cells.

Animals↗
PubMed1980

[Polyploidization mechanisms of the cardiac myocytes in the mouse].

Ventricular cardiomyocytes of 5-6 day-old mice are mostly polyploid. At this time 60% of the cardiomyocytes become binuclear and another 10% mononuclear polyploids. The binuclear cardiomyocytes emerge as a result of acytokinetic mitosis, while mononuclear tetraploids as a result of the cessation of the mitosis at the initial stages.

Animals↗
PubMed1980

[Polyploidization of hepatocytes under different regimens of rat liver exposed to CCl4].

Polyploidization of hepatocytes in albino rats subjected to continuous and intermittent exposure to CCl4 has been studied karyometrically. It has been shown that polyploidization as a response to the exposure of chlorderivatives of hydrocarbons is determined by hepatotoxin toxicity related to the number of chlorine atoms in the molecule and to the character of the exposure involving route, dose and regimen of exposure.

Animals↗
PubMed1993

Polyploidization by means of endoduplication in a human breast cancer cell line.

Near DNA diploid human adult solid tumors are often associated with certain near-tetraploid cells. In an established human breast cancer cell line, Hs578T, with a DNA index in the hyperdiploid region, polyploid cells appeared during exponential growth. Among clones generated from single cells and analyzed by the video time lapse technique, an intraclonal interdivision time (IDT) heterogeneity is presented that renders endoduplication a plausible explanation for the generation of the polyploid cells observed. This conclusion, drawn from our IDT analysis, is supported by curves drawn from counting grain-positive cells during continuous labeling with [3H]-thymidine. Our results are compared with a parallel analysis of the aneuploid human breast cancer cell line MDA-231, generating intraclonal IDT heterogeneity, due mainly to the mitotic instability of that line, as we reported previously.

Breast Neoplasms↗