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At least 19 recordsLinked to original sources

PubMedDate not supplied

Distribution of diploidy, polyploidy, and endoreduplication in fra(X) positive and negative lymphocytes, amniocytes, and chorionic villi.

Expression of fragile X [fra(X)] (q27.3) and endoreduplicated metaphases have been reported in methotrexate-treated (MTX) fra(X) cultures (Kerem B, Biotein R, Schaap T [1988]: Chromosoma 97: 6-10). Further, new data (Kimchi-Sarfaty C, Goitein R, Kerem B, Werner M, Medan B, Schaap T [1991]: Am J Med Genet, this issue) indicate that MTX may specifically induce polyploidy and endoreduplication in cells with the fra(X) mutation. To confirm and extend these results, we have studied short-term lymphocyte cultures incubated in M199, a folate deficient system, and RPMI-1640 in the presence and absence of 5-fluorodeoxyuridine (FUdR) exposure during the last day of a 4 day culture. No endoreduplicated cells were seen under these conditions and there was no change in the level of polyploidy. We also studied the distribution of polyploid and endoreduplicated cells in amniotic fluid and chorionic villus sample cultures from one fra(X) positive and 4 at-risk specimens. No increase in the incidence of polyploidy or endoreduplication was observed in cultures exposed to MTX for both 24 and 48 hours from a fra(X) positive amniotic fluid case. Cytogenetic results were fra(X) negative for the remaining 4 cases tested. There was significant discordance between our findings and those expected based on MTX-induced increased frequencies of polyploidy and endoreduplication. Thus, our studies do not confirm the reported correlation between the presence of FRAXA and increased frequencies of polyploidy and endoreduplication in MTX-exposed amniocyte cultures and there was no evidence for increased levels of polyploidy and endoreduplication in short-term fra(X) lymphocyte cultures exposed to non-MTX fra(X) induction.

Amniotic Fluid↗

PubMed1991

Noscapine-induced polyploidy in vitro.

The conditions under which noscapine causes high levels of polyploidy in vitro in human lymphocytes were investigated to try to determine its mode of action and to assess whether it was likely to be a genotoxic hazard when used as an antitussive agent. Irrespective of duration of treatment or type of medium, there seemed to be a threshold for polyploidy induction between 15.0 and 30.0 micrograms/ml and a maximum between 100.0 and 150.0 micrograms/ml noscapine. High levels (10.0-20.0%) of noscapine-induced polyploidy were never found with 4 h treatments or with RPMI 1640 medium plus 15% (v/v) foetal calf serum; the use of Iscove's modified Dulbecco's medium and 24 h treatments were needed. The reasons for these observations seemed to be the faster cell division and greater sensitivity of cells grown in Iscove's medium. There was conflicting evidence about the mechanism of polyploidy induction by noscapine; either spindle damage or cell fusion remain as possibilities. The need for prolonged exposure and the precise nutritional requirements suggest that a short exposure, albeit at high concentration, in the upper gastro-intestinal tract is unlikely to be a hazard for humans. Furthermore, evidence of a threshold at approximately 20 micrograms/ml plus the virtual elimination of noscapine-induced polyploidy by microsomal metabolism (S9 mix) together with published metabolic data imply that the low-level systemic exposure after absorption may well not be hazardous. We conclude that the use of noscapine in cough mixtures does not pose a significant potential hazard for humans.

Bromodeoxyuridine↗

PubMed1976

[Somatic polyploidy in animal embryogenesis].

The evidence provided in our laboratory on somatic polyploidy is reviewed. The development of some embryonal cell populations being taken as an example, the main problems of somatic polyploidy are discussed: somatic polyploidy and proliferation, growth, cell differentiation and specialization, the significance of polyploidy in the development of embryonal populations, in the realization of development programs etc. The term "somatic polyploidy" is not thought to involve the complex of phenomena it designates. A new, more precise and general concept is proposed--"hyperreplication of DNA", which seems to cover indeed the whole complex of phenomena characterizing the increase of DNA content in the nuclei of somatic cells including the polyploid ones.

Animals↗

PubMed1978

The development of polyploidy in two classes of rat liver nuclei.

Two classes of nuclei from livers of Sprague-Dawley rats were isolated, one pelleting in 2.3 M sucrose (H nuclei) and the second class sedimenting through 1.6 and 1.8 M sucrose and banding at the 1.8/2.3 M sucrose interface (L nuclei) of a three-step discontinuous gradient. In younger animals, the L nuclear fraction was the major fraction, but the percentage of nuclei found in the L fraction decreased as the animals grew. Nuclear ploidy was determined by flow microfluorometry using propidium iodide as a DNA stain. Both the H and L nuclear fractions contained diploid, tetraploid and octaploid nuclei; but the degree of polyploidy was greater in the H fraction. Concomitant with the change in distribution of nuclei between the H and L fractions with increasing age was a progressive increase in the degree of polyploidy in the H fraction. Polyploidy did not increase linearly with age in the H nuclear fraction but increased in cycles marked by large changes in the numbers of nuclei found in H and L nuclear fractions. By 12 weeks of age, 4n-H nuclei were the largest single population of nuclei in rat liver. These observations suggested that the shift of liver nuclei from the L fraction to the H fraction was associated with the development of polyploidy and with the differentiation of hepatocytes.

Aging↗

PubMed1979

[Polyploidizing mitoses and the biological meaning of polyploidy in liver cells].

The ontogenetic polyploidization of hepatocytes is regarded, within which normal mitoses are changed to polyploidizing mitoses, and diploid hepatocytes transform into polyploid mono- and binuclear cells. A new hypothesis is put forward of the biological significance of the liver cell polyploidy. The hypothesis takes into account a high level of spontaneous chromosomal aberrations in mitotic hepatocytes. The chromosome structural changes interfere with mitosis resulting in the chromosomal imbalance. Polyploidy bestows for hepatocytes a tolerance towards a chromosomal imbalance. Some implications of the hypothesis are discussed: unbalanced genome of hepatocytes after the treatment with mutagens and mitotic stimulators; the reasons of liver cell polyploidy differences in mammalian species; mechanisms of radioresistance of hepatocytes. Chromosomal imbalance of polyploid hepatocytes is assumed to be the basis for wome chronic liver diseases in man.

Animals↗

PubMedDate not supplied

Endoreduplication and polyploidy in fragile X cells induced by methotrexate and fluorodeoxyuridine: implications for diagnosis.

Lymphoblastoid cell lines from fragile X patients and amniotic cells from fragile X embryos, when cultured with methotrexate (MTX) or fluorodeoxyuridine (FUdR), showed a significant increase in endoreduplication and polyploidy. This phenomenon was not observed in fragile X lymphocytes or in lymphoblastoid cell lines and amniotic cells of normal control individuals. The relationship between the inducible fragile site at Xq27.3 and the inducible endoreduplication is discussed. The induction of endoreduplication and polyploidy in fragile X lymphoblasts and amniocytes is evaluated as a possible diagnostic test.

Amniotic Fluid↗

PubMed1991

Effect of dietary restriction and aging on polyploidy in rat liver.

Liver polyploidy levels were compared as a function of age and diet in male Fischer 344 rats between 1 and 24 months of age. Dietary restriction was imposed on one group by reducing their food intake to 60% of ad libitum food intake. Histological sections of the livers of animals at each age and diet were examined. Diploid, tetraploid and octaploid nuclei were observed, and their size and frequency established. There were no differences in the diameter or volume of these size classes as a function of age or diet. An age-related decline in the percentage of diploid nuclei, coupled with an increase in the percentage of tetraploid and octaploid nuclei was observed in both groups. The major difference between the two groups was that the adult level of liver polyploidy was attained more slowly in the animals on dietary restriction as compared to the ad libitum fed controls. Polyploid cell formation in the liver is under the control of growth hormone, thyroid hormone and thymus, all of which might be influenced by dietary restriction.

Aging↗

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↗

PubMed1975

Colcemid-induced polyploidy and aneuploidy in normal and tumour cells in vitro.

The frequency of colcemid-induced genome mutations (aneuploidy and polyploidy) in normal and SV40-transformed cultures of Djungarian hamster embryonic cells was studied. Genome mutations were easily induced by the drug in transformed but not in normal cultures. Elevation of colcemid concentration and prolongation of the incubation period did not substantially increase the frequency of genome mutations in normal cells. An attempt was made to study the causes of the differences in sensitivity to colcemid-mutagenicity of normal and transformed cells. Transformed cells did not include more 3H-colchicine than normal cells, and binding of the drug to cell homogenates was similar in both kinds of cultures. According to these data the higher sensitivity of transformed cells to colcemid is not connected either with increased permeability of the cell to the drug or with changes in its binding to tubulin.

Aneuploidy↗

PubMed1979

Polyploidy in insect evolution.

Of all living organisms insects are the group with the highest number of existing species. It is, of course, true that a fraction of the total number of insects has been cytologically studied. Polyploid forms are rare exceptions among them. Polyploidy in insects is always associated with the parthenogenetic mode of reproduction. The cytologically verified cases are described. As for the geographic distribution of polyploid insects, they have successfully colonized vast land areas. Their distributions are, in general, northern and montane. The polyploid races are in general far more widespread than their diploid bisexual ancestors. The possible models of origin of polyploid insects are covered as well as data on their gaenetic variability. There are apparent environmental correlations in the distribution of certain forms. Most polyploid insects have life cycles extending over two (or more) years. They are also in general flightless forms. Hypotheses on the relation between heterozygosity in polyploids as well as the consequences of mutations in polyploid lineages are also presented.

Animals↗

PubMed1979

Polyploidy, plants, and electrophoresis.

Investigations of polyploidy using electrophoresis are at present severely limited by several areas of difficulty which limit all applications of this technique. The technical problems inherent in electrophoresis of plants, namely extraction of active extracts and maximizing resolution of electrophoretic variants through investigation of gel and especially assay conditions, have never been addressed explicitly. No rationale for initiating work on a new species is available. Analytical approaches to defining the conditions which limit resolution are rare. Gel-to-gel variation is poorly controlled, seldom monitored. The individual nature of electrophoretic investigations limits the comparability of data among labs. In short, "hit-and-miss" approaches predominate, and these limit investigation. Techniques are now available which one can hope will greatly improve the experimental situation.

Animal Population Groups↗

PubMed1979

Polyploidy in algae.

The green algae and the charophytes represent the most widely studied groups of algae in respect to their ploidy levels. In some genera increased size accompanies ploidy level changes as well as certain morphological modifications, but in other genera no evident obvious changes can be discerned. In the other major groups of algae, namely the Rhodophycophyta and Phaeophycophyta, few cases of polyploidy have been documented adequately. In the remaining groups, unusual nuclear phenomena and/or behavior have hampered studies and few species have adequately been studied in regard to their polidy levels.

Eukaryota↗

PubMed1979

Polyploidy in fungi.

There is evidence supporting a concept of polyploid evolution in a number of groups of fungi. These typically have dominant diploid phases in their life-histories. There are a number of reports of suspected polyploidy in other fungi, but these should be considered speculative at this time.

Ascomycota↗

PubMed1977

Rapid determination of polyploidy in human chorionic tissue sections.

Chromosomal analysis from aborted tissue has become an important diagnostic aid. However, the necessary cultures are frequently unsuccessful due to the condition of the aborted tissue. Polyploidy, in particular triploidy, in the conceptus is a common cause of early pregnancy loss and unlike aneuploidy does not appear to be associated with an increased recurrence risk. The necessity to monitor a subsequent pregnancy with amniocentesis is therefore eliminated. Therefore, in cases where a chromosomal anomaly is probable, a fast simple method of identification of a polyploid karyotype would be valuable. In this presentation, we describe a method using a scanning light microscope and histologic tissue preparations. This method can accurately determine the ploidy of the aborted material in 5 days.

Abortion, Spontaneous↗

PubMed1976

Polyploidy in the pancreas of the normal and diabetic mutant mouse.

The DNA content of endocrine and exocrine pancreatic nuclei of normal C57BL/KsJ and diabetic mutant C57BL/Ks-db/db mice was measured by Feulgen microdensitometry. The exocrine and endocrine pancreatic nuclei of the 4-week-old normal, 12-week-old normal, and 4-week-old (prehyperglycaemic) diabetic mutant mice contained diploid and tetraploid cells, while the 12-week-old (established hyperglycaemic) mutant contained diploid, tetraploid, and octaploid nuclei. The polyploidy in the endocrine pancreas of all these mice was confined to the B-cells, while the A-cells were always diploid.

Age Factors↗

PubMed2026

Polyploidy Arithmetic.

Polyploidy occurs in plants and animals, and is an important force in speciation and genome evolution. The main focus of this paper is the following fundamental question that was recently posed by Huber and Maher: Given the ploidy numbers of a collection of extant species, or their ploidy profile, what is the smallest number of hybridizations needed in any evolutionary history for these species to completely represent these numbers? In this paper, we shall show that this question can be rephrased in terms of addition chains and the closely related addition sequences, which have been studied for over a century in mathematics and computer science. These are sequences of natural numbers that start with 1, so that each number in the sequence larger than 1 is the sum of two other numbers arising earlier in the sequence. In our first main result, we show that finding the smallest number of hybridization events to explain a ploidy profile, or the hybrid number, is equivalent to solving the so-called addition sequence problem. This immediately implies that computing the hybridization number is computationally intractable. Even so, it also leads to new connections to representing polyploid evolution using networks. More specifically, in our second main result we show that ploidy profiles representable by tree-child networks are exactly the addition chains, implying a polynomial-time algorithm for identifying these profiles. We then consider beaded tree-child networks, which permit the representation of autopolyploidy events, and in our third main result we provide a greedy polynomial-time algorithm to decide whether a given profile can be realized by such a network. We expect that our results can be leveraged in future work through, for example, making use of known algorithms for computing short addition sequences to give bounds for the hybrid number, and in guiding network reconstruction for polyploid species.

Polyploidy↗

PubMed1991

Polyploidy induction as a consequence of topoisomerase inhibition. A flow cytometric assessment.

Following recovery from a 4-hr exposure to clinically achievable concentrations of the topoisomerase II inhibitors Adriamycin, teniposide, or amsacrine or the putative topoisomerase II inhibitor crisnatol, murine erythroleukemic cells remained viable for up to 48 hr, but did not proliferate. Cell cycle analysis after a 24-hr recovery revealed blocks in G2 (4N DNA) or greater than G2 (up to 8N DNA) polyploid stages. The relative percentages of cells in either stage was a function of drug concentration and cell cycle stage at time of exposure: typically, cells exposed during S phase became blocked in G2, whereas those exposed during G2/M progressed into greater than G2 polyploid stages. G2-blocked cells exhibited a 2- to 3-fold increase in nuclear protein content and cellular/nuclear volume (i.e. unbalanced growth) and approximately 5% more DNA stainability (as a consequence of nuclear conformational changes rather than redundant DNA synthesis). In all cases, at the drug concentrations studied, mitotic figures were absent and G2 and greater than G2 blocks were irreversible, indicating that the mechanism of polyploidy induction differs from that of microtubule inhibitors. These findings suggest that although topoisomerase inhibitors interfere with DNA synthesis in the S phase, their induction of greater than G2 polyploid blocks may involve direct or indirect inhibition of chromosome condensation.

Amsacrine↗