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PubMed1999

Induction of polyploidy and apoptosis after exposure to high concentrations of the spindle poison nocodazole.

The proportions of aneuploid/polyploid versus euploid cells formed after treatment with spindle poisons like nocodazole are of course dependent on the relative survival of cells with numerical chromosome aberrations. This work aimed at studying the survival of polyploid cells formed after treatment with a nocodazole concentration sufficient to significantly decrease tubulin polymerization (0.1 microg/ml). First, normal primary lymphocytes were analysed and the following complementary chromosomal parameters were quantified: mitotic index, frequency of abnormal mitoses, polyploid metaphases and apoptotic cells. The results clearly indicate a positive correlation between abnormal mitotic figures, apoptosis and the induction of polyploidy. They therefore led to a single cell approach in which both apoptosis and polyploidy induction could be scored in the same cell. For this purpose, actively proliferating cells are required and two human leukaemic cell lines were used, KS (p53-positive) and K562 (p53-negative), which have a near-triploid karyotype. Cells were separated into an apoptotic and a viable fraction by means of annexin-V staining and flow cytometry. In KS, treatment with nocodazole induced a similar fraction of hexaploid cells in both the viable and apoptotic fraction, but no dodecaploid cells were ever observed. In contrast, a population of dodecaploid cells (essentially viable) was clearly observed in the K562 cell line. The results in KS, as compared with K562, confirm that wild-type p53 can prevent further cycling of polyploid cells by blocking rereplication. The most probable explanation for these data is that not only the mitotic spindle but also interphase microtubules are sensitive to nocodazole treatment. Our data thus strongly suggest that besides the G(1)/S checkpoint under the control of p53, the G(2)/M transition may be sensitive to depolymerization of microtubules, possibly under the control of Cdc2, Bcl-2, Raf-1 and/or Rho.

Adult↗
PubMed1991

Investigations into the induction of aneuploidy and polyploidy in mammalian cells by the anti-tussive agent noscapine hydrochloride.

Noscapine, a non-narcotic, centrally-acting anti-tussive drug induces polyploidy in Chinese hamster CHL cells; further studies were carried out to investigate whether similar effects could be induced in other rodent cells (Chinese hamster V79) and in human lymphocytes. In both cases, large increases in the frequency of polyploid cells were induced at test concentrations ranging from 15 to 120 micrograms/ml after 24 and 48 h continuous treatment in the absence of S9 mix. In addition, spindle damage was observed in V79 cells and human skin fibroblasts after 24 h treatment with test concentrations of 30 and 60 micrograms/ml. Furthermore, after treatment of human skin fibroblasts there was a marked increase in the proportion of cells containing chromosomes which had become dislocated from the spindle. Treatment of the mouse/human hybrid cell line R3-5 induced a significant increase in the number of 6-thioguanine resistant colonies and it was confirmed cytogenetically that these colonies had arisen due to loss of human chromosome 2. From these experiments it can be concluded that noscapine induces polyploidy in both rodent and human somatic cells, and that this could arise through a direct effect upon spindle structure and/or function. The aneugenic properties of noscapine are less certain and further work is required in this area. Exposure to the drug through its therapeutic use (15mg up to four times daily) could exceed, at least locally within the gastrointestinal (GI) tract, the concentration range shown to be active in these in vitro studies. An immediate topical hazard might exist within the buccal cavity and GI tract, but further confirmation of these in vitro results are required using suitable in vivo systems before definite conclusions can be made regarding any potential hazard associated with the administration of this drug.

Aneuploidy↗
PubMed2003

A recent polyploidy superimposed on older large-scale duplications in the Arabidopsis genome.

The Arabidopsis genome contains numerous large duplicated chromosomal segments, but the different approaches used in previous analyses led to different interpretations regarding the number and timing of ancestral large-scale duplication events. Here, using more appropriate methodology and a more recent version of the genome sequence annotation, we investigate the scale and timing of segmental duplications in Arabidopsis. We used protein sequence similarity searches to detect duplicated blocks in the genome, used the level of synonymous substitution between duplicated genes to estimate the relative ages of the blocks containing them, and analyzed the degree of overlap between adjacent duplicated blocks. We conclude that the Arabidopsis lineage underwent at least two distinct episodes of duplication. One was a polyploidy that occurred much more recently than estimated previously, before the Arabidopsis/Brassica rapa split and probably during the early emergence of the crucifer family (24-40 Mya). An older set of duplicated blocks was formed after the monocot/dicot divergence, and the relatively low level of overlap among these blocks indicates that at least some of them are remnants of a larger duplication such as a polyploidy or aneuploidy.

Arabidopsis↗
PubMed1988

Vascular smooth muscle polyploidy in the development and regression of hypertension.

1. Two groups of spontaneously hypertensive rats (SHR) were treated with enalapril (25-30 mg/kg per day): Group I received treatment from 4 to 14 weeks of age to inhibit development of hypertension and Group R received the drug from 14 to 20 weeks of age to reverse established hypertension. 2. Systolic blood pressure, ploidy of aortic smooth muscle cells (flow cytometric DNA analysis) and aortic hypertrophy (medial cross-sectional area) were determined at times both during and after enalapril treatment (up to 30 weeks). 3. Enalapril treatment normalized blood pressure to that of age-matched Wistar-Kyoto rats in both groups. Blood pressure rose again following cessation of treatment. 4. In untreated SHR the incidence of polyploid cells increased concomitantly with increasing pressure throughout the time studied, whereas in Group I the incidence remained low. In Group R, the incidence of polyploidy directly paralleled both the decrease (normalization) and the rise in blood pressure following cessation of treatment. 5. Hence, the incidence of vascular smooth muscle cell polyploidy is not simply a result of growth of the vessel with increasing age of the SHR, but parallels inhibition, reversal, and redevelopment of hypertension.

Aging↗
PubMed1984

Polyploidy and nuclear phenotypes in salivary glands of the rat.

This work describes polyploidy characteristics and nuclear phenotypes with advancing age in salivary glands of the rat. Feulgen-stained nuclei from squashed salivary gland fragments and nuclei isolated from homogenized salivary glands were analyzed with automatic scanning cytophotometry using Zeiss equipment and a Microdata computer. Polyploidy was demonstrated even in the submaxillary glands of young animals which exhibited 2C and 4C Feulgen-DNA classes. Glands from 1.5 year-old rats displayed diploid, tetraploid, and octaploid nuclei. Parotid glands from young animals exhibited Feulgen-DNA values pertaining to 2C, 4C, and 8C classes, whereas those from aged animals exhibited values pertaining to these classes and to the 16C one. The polyploid nuclei of both glands showed mean absorbances higher than those of diploid nuclei, which is assumed to be due to an increase in the chromatin packing state accompanied by redistribution of the heterochromatin areas. Feulgen-DNA values -nuclear surface and average absorption ratio- surface covered by condensed chromatin correlations support these assumptions.

Aging↗
PubMed1964

POLYPLOIDY INDUCED BY X-RAYS IN CHINESE HAMSTER CELLS IN VITRO.

The incidence of polyploidy (specifically, in this case, the doubling of the stemline chromosome number) induced by x-rays in cells cultured in vitro is about the same for both "near-diploid" and "near-tetraploid" sublines of the Chinese hamster. Endoreduplication is a principal cytological mechanism for this form of induced polyploidy.

Animals↗
PubMed2000

Polyploidy and the evolution of gender dimorphism in plants.

Gender dimorphism and polyploidy are important evolutionary transitions that have evolved repeatedly in many plant families. We show that gender dimorphism in North American Lycium (Solanaceae) has evolved in polyploid, self-compatible taxa whose closest relatives are cosexual, self-incompatible diploids. This has occurred independently in South African Lycium. We present additional evidence for this pathway to gender dimorphism from 12 genera involving at least 20 independent evolutionary events. We propose that polyploidy is a trigger of unrecognized importance for the evolution of gender dimorphism, which operates by disrupting self-incompatibility and leading to inbreeding depression. Subsequently, male sterile mutants invade and increase because they are unable to inbreed.

Alleles↗
PubMed2004

Human papillomavirus type 16 E6 and E7 cause polyploidy in human keratinocytes and up-regulation of G2-M-phase proteins.

Human papillomavirus type 16 proteins E6 and E7 have been shown to cause centrosome amplification and lagging chromosomes during mitosis. These abnormalities during mitosis can result in missegregation of the chromosomes, leading to chromosomal instability. Genomic instability is thought to be an essential part of the conversion of a normal cell to a cancer cell. We now show that E6 and E7 together cause polyploidy in primary human keratinocytes soon after these genes are introduced into the cells. Polyploidy seems to result from a spindle checkpoint failure arising from abrogation of the normal functions of p53 and retinoblastoma family members by E6 and E7, respectively. In addition, E6 and E7 cause deregulation of cellular genes such as Plk1, Aurora-A, cdk1, and Nek2, which are known to control the G(2)-M-phase transition and the ordered progression through mitosis.

Cell Cycle Proteins↗
PubMed1986

Induction of polyploidy in cultures of neonatal rat aortic smooth muscle cells.

Arterial smooth muscle cells become tetraploid with age and hypertension. To further study this phenomenon, neonatal rat aortic smooth muscle cells were placed in cell culture and studied over time. Numerous cells with tetraploid and even octaploid DNA content appeared beginning in primary cultures. These increases in DNA content per cell were determined by quantitative fluorescence microscopy and flow cytometry, and true polyploidy was confirmed by chromosome counts. In contrast, cells from adult rat aortas failed to produce significant polyploid cells over time in culture. In vitro culture of neonatal aortic cells may therefore be a model system for studying the initiation of polyploidy in arterial smooth muscle.

Actins↗
PubMed2006

Regulated polyploidy in halophilic archaea.

Polyploidy is common in higher eukaryotes, especially in plants, but it is generally assumed that most prokaryotes contain a single copy of a circular chromosome and are therefore monoploid. We have used two independent methods to determine the genome copy number in halophilic archaea, 1) cell lysis in agarose blocks and Southern blot analysis, and 2) Real-Time quantitative PCR. Fast growing H. salinarum cells contain on average about 25 copies of the chromosome in exponential phase, and their ploidy is downregulated to 15 copies in early stationary phase. The chromosome copy number is identical in cultures with a twofold lower growth rate, in contrast to the results reported for several other prokaryotic species. Of three additional replicons of H. salinarum, two have a low copy number that is not growth-phase regulated, while one replicon even shows a higher degree of growth phase-dependent regulation than the main replicon. The genome copy number of H. volcanii is similarly high during exponential phase (on average 18 copies/cell), and it is also downregulated (to 10 copies) as the cells enter stationary phase. The variation of genome copy numbers in the population was addressed by fluorescence microscopy and by FACS analysis. These methods allowed us to verify the growth phase-dependent regulation of ploidy in H. salinarum, and they revealed that there is a wide variation in genome copy numbers in individual cells that is much larger in exponential than in stationary phase. Our results indicate that polyploidy might be more widespread in archaea (or even prokaryotes in general) than previously assumed. Moreover, the presence of so many genome copies in a prokaryote raises questions about the evolutionary significance of this strategy.

Archaea↗
PubMed2003

Quantitative analysis of transcript accumulation from genes duplicated by polyploidy using cDNA-SSCP.

Repeated rounds of polyploidy have been commonplace in the lineages leading to modern eukaryotic genomes, giving rise to widespread gene duplication. Genes duplicated by polyploidy, or "homoeologs," may continue to be expressed at equal levels following polyploidization or their expression may be dramatically altered. In this report, we describe how SSCP analysis of RT-PCR products can be used to evaluate the expression status (presence and relative quantity) of highly similar homoelogous gene pairs from an allotetraploid genome. This cDNA-SSCP approach was used to evaluate transcript abundance in "synthetic tetraploid" mRNA pools (i.e., mixtures of diploid products) and three natural homoeologous gene pairs expressed in tetraploid cotton (Gossypium hirsutum) ovules. Results from replicated tests show that cDNA-SSCP reliably separates duplicated transcripts with 99% sequence identity. Most significantly, the method yields quantitative estimates of transcript ratios in template pools that range from equimolar to approximately 100:1.

DNA, Complementary↗
PubMedDate not supplied

Dolastatin-10 induces polyploidy, telomeric associations and apoptosis in a murine melanoma cell line.

Our purpose was to study the effects of dolastatin-10 (Dol-10) on chromosome morphology, telomeric associations, induction of polyploidy and cell death in a metastatic murine melanoma cell line, K1735 clone X-21. Murine melanoma cells were treated with various concentrations (10 ng/ml, 100 ng/ml and 1000 ng/ml) of Dol-10 for 4, 24 and 72 h continuously and harvested immediately without recovery. In another set of experiments, cells were treated for 4 h with the same concentrations, washed with prewarmed medium and then allowed to recover in drug-free medium for 24 h and subsequently harvested. Our preliminary results indicated: i) a drug-mediated increase in the frequency of metaphases, with telomeric associations resulting in multicentric and ring configurations; ii) induction of clumping in metaphase chromosomes; iii) induction of polyploidy as a result of endoreduplication; iv) formation of micronucleated cells; and v) induction of cell death. These observations indicated that Dol-10 could be a potent antineoplastic drug against malignant melanoma. In addition to its reported interaction with cell microtubules, the mechanism of action of Dol-10 may be mediated through the loss of telomeric repeats and induction of chromosome aberrations.

Animals↗
PubMed2005

Enforced adhesion of hematopoietic cells to culture dish induces endomitosis and polyploidy.

Cells of epithelial or endothelial lineage when forced to grow in suspension undergo the detachment-induced death termed "anoikis". In the present study we explored the reverse situation namely the effect of enforcement of hematopoietic lineage cells that are normally maintained in suspension to grow attached. Towards this end murine L1210 or human HL-60 and Jurkat leukemia cells were cultured in slide chambers coated with poly-L- or poly-D- lysine, or with compound 48/80, the polycations attracting them electrostatically. Within minutes after the transfer L1210 cells strongly adhered to bottom surface of the dish and shortly thereafter binuclear-, and later on, polynuclear-cells become apparent. The frequency of nuclei per cell was increasing with time and polykaryons with up to 16 nuclei and high DNA ploidy (DI = 16.0) were apparent after 48 h. After 4 days the size (volume) of some polykaryons exceeded by over 340-fold the volume of mononuclear cells. The presence of mitotic figures and abnormal mitotic spindles in adhering polykaryons provided evidence of the impeded cytokinesis that led to endomitosis. Most polykaryons excluded trypan blue, had balanced growth (unchanged protein/DNA ratio compared to monokaryons), and showed no evidence of apoptosis. Individual nuclei within each polykaryon replicated DNA in synchrony. The strong cell attachment and aborted cytokinesis were cell line specific since no significant endomitosis was observed in Jurkat- or HL-60- cells which did not strongly attach to polycation-coated surfaces. Defective cytokinesis and induction of polyploidy by this mechanism, if occurs in vivo (e.g., mediated by integrins), may lead to aneuploidy and therefore have tumorigenic consequences. The phenomenon offers novel experimental model for induction of polyploidy and provides alternative to cytocholasin B to prevent cytokinesis in the mutagenicity cytokinesis-blocked micronucleus (CBMN) assay.

Animals↗
PubMed1975

Polyploidy in the human myometrium.

In an investigation to determine whether the enlargement of cells and nuclei in the myometrium of the human uterus during pregnancy is related to the development of polyploidy or not, the following facts were established, mainly on the basis of cytophotometric analysis of nuclei isolated with a newly developed mechanical technique from a series of uteri in different states with regard to the reproductive process (juvenile, nulligravida, gravida, sectio parva, sectio caesarea). 1. Polyploid nuclei arise only during pregnancy. They can still be found for many years after the puerperium; their occurrence, however, remains a discrete phenomenon. 2. During pregnancy, a swelling of virtually all diploid nuclei is observed, which is present as early as 16 weeks after conception, but a significant increase of the nuclear projection area is found only in the Caesarean section group. This swelling, which (might occur under hormonal influence is possibly of a functional nature and is separate from the development of polyploidy as such. 3. By means of the tracing of double sex chromatin bodies in the nuclei, the occurrence of tetraploid nuclei in the myometrium could be demonstrated both in nuclear suspensions and in sections of intact uterine wall.

Cell Nucleus↗
PubMedDate not supplied

[The effect of the alkylating carcinogen dipin on the proliferation, the level of polyploidy development and on micronucleus formation in a population of parent and newly formed hepatocytes].

In the process of hepatocarcinogenesis induced by dipin and partial hepatectomy in mice, initial hepatocytes are gradually replaced with a population of newly formed hepatocytes which originate from oval cells (Radaeva, Factor, 1990). It has been shown that the increase in hepatocarcinogenesis duration (2-11 weeks) along with the intensification of oval-cell reaction are accompanied by a progressive injury of cell genome in the initial hepatocyte population. This injury manifests itself by an accumulation of cells with micronuclei as well as by the development of high levels of polyploidy and aneuploidy. In the initial parenchyma, clastogenic and aneuploidizing effects of dipin are maximally pronounced at the stage of appearing hepatocyte nodules which consist of newly formed hepatocytes (8-11 weeks). By this time the proliferative pool comprises 83-92%, the amount of aberrant cells increases in average from 7 to 50%, and the indices of average nuclear ploidy in population enhance 6-8 times as compared with the average level of polyploidy in normal parenchyma. The quota of binuclear cells without micronuclei abruptly falls while the quota of binuclear cells with micronuclei and nuclear bridges increases reaching 3/4 of the total amount of binuclear cells. Binuclear cells with nuclear bridges comprise about one third of binuclear cells with micronuclei. At the stage of hepatocytic nodules (8-11 weeks after induction), the population of newly formed hepatocytes is characterized by the absence of morphologically damaged cells and of cells with micronuclei, a low incidence of binuclear cells (1-3%), and a high value of proliferative pool (83-96%).

Alkylating Agents↗
PubMed2002

[Evolutionary regularities of the somatic polyploidy manifestation in salivary glands of gastropod molluscs. IV. A subclass of Pectinibranchia: Orders Hamiglossa and Toxoglossa (Neogastropoda)].

Salivary glands of 12 species of carnivorous gastropod molluscs, making the Neogastropoda group have been investigated by histochemical methods and DNA cytophotometry. We studied the anatomical and histological structure of ordinary (acinous) and accessory (tubular) salivary glands, and of unpaired glands (Leiblen's, "framboisée", and poisonous). Cells of three types were distinguished: granular cells (with glycoproteid granular inclusions), mucocytes-I (with sulfatic acid mucopolysaccharides), and epithelial ciliated cells. In ordinary and accessory glands of the studied Neogastropods, polyploid cells with polyploidy levels from 4c to 16c were revealed together with diploid cells. The functional significance and phylogenetic tendencies of polyploidy manifestation in salivary glands of prosobranch gastropods are discussed.

Animals↗
PubMed2006

[Study on induction of polyploidy in Salvia bowleyana by colchicine treatment].

OBJECTIVE: To explore the technique of induction of polyploidy in Salvia bowleyana by colchicine treatment. METHOD: The three kinds of explant of bud, leaf and calli were induced by colchicine treatment. RESULT: The induction effects were better when the calli was treated by colchicines (15 mg x L(-1)) and the leaf was pre-cultured for one week. The doubling rate was 33.33%, while the majority were wholy doubled plants, and the leaves were thicker and broader, the color was darker, the root was thicker and the stoma size was obviously bigger than the diploid plants. The number of chromosome were 8 to 64. Isoenzyme analysis showed that the enzyme activities between the polyploid and the diploid plants were quite different. CONCLUSION: Induction of polyploidy by colchicine treatment is efficacious. The part of the doubled plants were identified as homologmous tetraploids.

Chromosomes, Plant↗
PubMed1990

[IBL like T cell lymphoma associated with hemolytic anemia and polyploidy chromosomal abnormality--a case report].

A 56-year-old man was admitted to Sapporo Kitano Hospital on May 30, 1987 because of fever, retention of ascites and pleural effusion, generalized lymphnode swelling and hepatosplenomegaly. Laboratory findings showed Coombs' positive hemolytic anemia, leukocytosis and polyclonal hypergammaglobulinemia. Serological test included positive RA factor, anti-DNA 16 U/ml, thyroglobulin Ab 1600 x and microsome Ab 3200 x. A cervical lymphnode specimen exhibited typical histologic picture of IBL like T cell lymphoma. The surface markers of lymphoma cells were CD2(+), CD8(+) and CD4(-). Chromosomal analysis of these cells revealed polyploidy abnormality for all chromosomes except for No. 14's which are disomy. All lymphoma cells have XXY sex chromosome and mar1, mar2, mar3. Gene rearrangement for beta-chain of T cell receptor was proved in these lymphoma cells. He was treated with prednisolone, vincristine, cyclophosphamide, adriamycin etc, but died of respiratory failure 171 days after admission. We reported a rare case of IBL like T cell lymphoma with polyploidy chromosomal abnormality accompanied with hemolytic anemia.

Anemia, Hemolytic↗