Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polyploidy”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources
PubMedDate not supplied

[The replicative potential of hepatocytes and liver stem cells].

The cellular basis of liver growth is reviewed from overall recent and previous data. According to the present-day ideas, the adult mammalian liver contains at least two cellular populations with many properties similar to the stem cells of renewing tissues that provide for the liver postnatal growth and parenchyma regeneration under various conditions. According to the present nomenclature, the differentiated parenchyma cells--hepatocytes--are a unipotent committed population of stem cells. In addition, there is a system of nonparenchymal multipotent stem cells or oval cells in the liver. Certain key models of liver growth, regeneration, and repopulation that contributed to development of these notions are considered. The recent data are discussed in the context of yet unclear cellular mechanisms providing for the tremendous replicative potential of hepatocytes, the role of polyploidy in the growth effects, and the sources of malignant transformation in the liver.

Animals↗
PubMedDate not supplied

[The molecular genetic differentiation of cultured Saccharomyces strains].

A comparative molecular genetic study of cultured Saccharomyces strains isolated from the surface of berries and various fermentation processes showed that baker's yeast and black-currant isolates contain not only Saccharomyces cerevisiae but also S. cerevisiae and S. bayanus var. uvarum hybrids. The molecular karyotyping of baker's, brewer's, and wine yeasts showed their polyploidy. The restriction enzyme analysis of noncoding rDNA regions (5.8S-ITS and IGS2) makes it possible to differentiate species of the genus Saccharomyces and to identify interspecies hybrids. The microsatellite primer (GTG)5 can be used to study the populations of cultured S. cerevisiae strains.

Beverages↗
PubMed2005

Cytogenetics of swarm rat chondrosarcoma.

The Swarm rat chondrosarcoma is a tumor tissue line derived from a tumor that arose spontaneously in a Sprague-Dawley rat. The original tissue has given rise to several tissue lines and cell lines that have been prepared in different laboratories. It has been observed that these lines differed in their growth rates and biochemical characteristics. We have characterized our Swarm rat chondrosarcoma tissue and cell lines currently in use in terms of their cytogenetic profiles and their tumorigenic properties in vivo. We found a wide variety of chromosomal abnormalities among cell lines, including translocations, deletions and polyploidy. There were also significant differences in their growth properties in vivo, giving rise to tumors of a few milligrams in the case of Ng cells, to 35 grams in the tissue line JWS. The cytogenetic complexity of the Swarm rat chondrosarcoma between and among different lines makes it very suitable to address questions about the changes that occur as a result of karyotypic abnormalities and to provide links between cytogenetic abnormalities and the dynamic oncogenic machinery.

Animals↗
PubMed2005

Selection for phenotypic divergence between diploid and autotetraploid Heuchera grossulariifolia.

Much of the diversity of flowering plants is associated with genomic duplication through polyploidy. Little is known, however, about the evolutionary mechanisms responsible for the diversification of novel polyploid lineages. We evaluated the possibility that divergence is driven by natural selection by estimating the strength of phenotypic selection acting on three floral traits in sympatric populations of diploid and autotetraploid Heuchera grossulariifolia over three years. Our results demonstrate consistent directional selection for increasing scape length and floral display in both diploid and tetraploid populations. In contrast, selection acting on flowering phenology varied across year and ploidy. Specifically, selection was found to favor late-flowering diploids in 2001 and 2002 but early-flowering tetraploids in 2003. We investigated the mechanistic basis of divergent selection for flowering phenology in 2003 by estimating the relationship between plant flowering phenology and the probability of intercytotype pollinator movement. The results demonstrated that less divergent tetraploids were significantly more likely to experience intercytotype flights than were more divergent tetraploids. This result is consistent with the pattern of phenotypic selection observed. Taken together, our results suggest that divergence of polyploids and their diploid progenitors may be driven by a process analogous to reinforcement whereby selection favors phenotypes that reduce the probability of intercytotype matings with reduced fertility.

Flowers↗
PubMed2005

[Diagnosis of numerical chromosomal aberrations in the cells of spontaneous abortions by multicolor fluorescence in situ hybridization (MFISH)].

According to different estimates, as high as 15-20% of all the pregnancies result in spontaneous abortions (SA) at different gestational periods. Identification of abnormalities leading to SA is of great importance for practical medicine, mainly for medical genetic counseling of married couples with impaired reproductive function. The diagnosis of chromosomal aberrations on the basis of SA materials is known to have a number of methodological difficulties. The present paper deals with the identification of numerical anomalies in the SA material by multicolor fluorescence in situ hybridization (MFISH). This technique using an original collection of DNA probes for chromosomes 1, 9, 13/21, 14/22, 15, 16, 18, X, and Y was applied to the study of chromosomal aberrations in 224 spontaneous abortion specimens. Numerical chromosomal aberrations were found in 122 (54.5%) cases. The cells of all the studied specimens exhibited aneuploidy of chromosome X in 17% cases; chromosome 16 in 12%, chromosomes 13/21 in 5.8%, chromosomes 14/22 in 4.9%, chromosomes 9 and 18 in 1.3% (each), chromosome 15 in 0.9%, chromosome 1 in 0.45%. Polyploidy was detected in 13.3% of cases; concomitant abnormalities were found in 7 cases. Analysis of the findings has led to the conclusion that MFISH can be successfully used in the diagnosis of numerical chromosomal aberrations of CA cells.

Abortion, Spontaneous↗
PubMed2005

Genotoxic effects of rotenone on cultured lymphocytes.

Rotenone is a heterocyclic compound widely used as an insecticide, acaricide and piscicide. Its toxicity is mainly caused by the inhibition of mitochondrial respiratory processes and ATP production, resulting in the generation of reactive oxygen species. Reactive oxygen species can interact with DNA, RNA and proteins, leading to cell damage, followed by death. We used the Comet assay, and we analyzed chromosome aberrations, in order to evaluate the genotoxic and clastogenic effects of rotenone on the different phases of the cell cycle. Cultured human lymphocytes were treated with 1.0, 1.5 and 2.0 microg/mL rotenone during the G1, G1/S, S (pulses of 1 and 6 h), and G2 phases of the cell cycle. Rotenone induced DNA damage and was clastogenic, but the clastogenicity was detected only with treatments conducted during the G1/S and S phases of the cell cycle. Rotenone also induced endoreduplication and polyploidy in treatments made during G1, while it significantly reduced the mitotic index in all phases of the cell cycle.

Adult↗
PubMed2006

Donor-derived type II pneumocytes are rare in the lungs of allogeneic hematopoietic cell transplant recipients.

Lung injury is a common cause of death and disability. Stem cell-related therapies are widely viewed as offering promise for people suffering from various types of pulmonary diseases, and gender-mismatched bone marrow transplant recipients serve as natural populations in which to study the role of bone marrow-derived stem cells in recovery from pulmonary injury. We evaluated the extent of lung repopulation by type II pneumocyte descendents of adult bone marrow-derived stem cells in allogeneic hematopoietic cell transplant recipients. Recut sections were obtained from five lung biopsy specimens and autopsy lung tissues from four female recipients of transplanted mobilized peripheral blood stem cells or bone marrow from male donors. Sequential immunohistochemistry and fluorescence in situ hybridization was performed on each section to evaluate for Y-chromosome-containing type II pneumocytes. A single Y-chromosome-containing type II pneumocyte was found in one lung biopsy from one hematopoietic cell transplant recipient. After adjustment for the effects of incomplete nuclear sampling, this pneumocyte represented 1.75% of all type II pneumocytes in the biopsy sample. There was no evidence of polyploidy to suggest cell-to-cell fusion. No donor-derived type II pneumocytes were found in samples from the other three patients. In conclusion, repopulation by bone marrow-derived stem cells or their progeny occurs at a low frequency in the lungs of hematopoietic cell transplant recipients. Conversely, proliferation by local stem cell populations appears to be more important for recovery from alveolar injury.

Adult↗
PubMed2006

The evolution of unisexuality in Calligrapha leaf beetles: molecular and ecological insights on multiple origins via interspecific hybridization.

Interspecific hybridization is a well-established cause of unisexual origins in vertebrates. This mechanism is also suspected in other apomictic taxa, but compelling evidence is rare. Here, we evaluate this mechanism and other hypotheses for the evolutionary origins of unisexuality through an investigation of Calligrapha leaf beetles. This group provides an intriguing subject for studies of unisexual evolution because it presents a rare insect example of multiple apomictic thelytokous species within a primarily bisexual genus. To investigate unisexual evolution, this study conducts the first molecular systematic analysis of Calligrapha. This involved the collection and analysis of about 3000 bp of DNA sequences--representing RNA and protein-coding loci from mitochondrial and nuclear genomes--from 54 specimens of 25 Calligrapha species, including four unisexual tetraploid taxa. Phylogenetic and molecular clock analyses indicated independent and single evolutionary origins of each of these unisexual species during the Pleistocene. Significant phylogenetic incongruence was detected between mitochondrial and nuclear datasets and found to be especially associated with the asexual taxa. This pattern is expected when unisexual lineages arise via interspecific hybridization and thus represent genetic mosaics that possess certain nuclear alleles from the paternal species lineage and mitochondrial DNA (mtDNA) alleles from the maternal parent. Analyzing the mtDNA and nuclear relatedness of unisexuals with corresponding haplotypes of bisexual Calligrapha species allowed the putative identification of these maternal and paternal species lineages for each unisexual species. Strong phenotypic similarities between unisexual taxa and their paternal parent species supported a model that involves both backcrosses of interspecific hybrids with a paternal parent and unreduced gametes. This model accounts for the origins of apomixis, polyploidy, and an overrepresentation of paternal nuclear alleles (and associated phenotypes) in unisexuals. This model is also consistent with the tetraploid karyotypes of unisexual Calligrapha, in which three sets of chromosomes (of presumed paternal ancestry) are quite morphologically homogeneous compared to the fourth. Especially intriguing was a consistent association of unisexual species with the host plant of the paternal parent but never with the maternal host. The statistical implausibility of these patterns occurring by chance further supports our inference of parental species. Moreover, it points to a potentially critical role for host-association in the formation and preservation of unisexual lineages. These findings suggest that ecological factors are critical for the diversification of unisexual as well as bisexual taxa and thus point out new research directions in the area of ecological speciation.

Animals↗
PubMed2006

[Loss of heterozygosity on chromosomes 1 and 19 in cases of primary brain tumour].

INTRODUCTION: Histological classification of brain tumours, including gliomas, can be difficult, and genetic investigations are increasingly significant in their classification and the development of treatment strategies. Oligodendrogliomas often show a loss of heterozygocity for the short arm of chromosome 1 and the long arm of chromosome 19 (LOH 1p/19q), changes that influence both treatment and prognosis. Our aim was to evaluate the incidence of combined loss of heterozygocity 1p and 19q in various glioma groups. MATERIALS AND METHODS: A total of 10 oligodendrogliomas (5 WHO grade II and 5 grade III), 10 mixed gliomas (5 WHO grade II and 5 grade III), 10 astrocytomas (5 WHO grade II and 5 grade III) and 11 glioblastomas (WHO grade IV) were investigated. Normal hippocampal tissue was used as a control. Formalin-fixed paraffin-embedded tissue was scrutinized with fluorescent in situ hybridization (FISH) with fluorochrome-conjugated double-strand DNA probes for 1p and 19q, respectively. RESULTS: A significiant loss of 1p/19q was found in the oligodendrogliomas; the astrocytomas showed a selective loss of 19q; the glioblastomas showed a selective loss of 1p but also polyploidy. CONCLUSION: This investigation confirms other reports on increased LOH 1p/19q in oligodendrogliomas. Various studies have demonstrated a large variation in the incidence of LOH 1p/19q. This might be due to inter- and intraobserver variability in the histological classification. Another factor might be variations in techniques. Most studies have been made on imprints. A standard for the method, including the number of cells counted, the cutoff limit and the statistical variation, is necessary for future studies and clinical use.

Astrocytoma↗
PubMed1991

[Chromosome analysis in spontaneous abortion using direct preparation of chorionic villi].

Two hundred cases of spontaneous abortions were studied by analysing chromosomes directly from chorionic villi. Abnormal karyotypes were found in 52% of the investigated cases. Among the chromosome abnormalities the most frequent were the trisomies (56.7%) followed by polyploidy (23.1%), monosomy X (15.4%) and structural anomalies (4.8%). The rapid and relatively simple method is suitable for studying the causes of spontaneous abortions, and these information may be helpful also for genetic counselling.

Abortion, Missed↗
PubMed1991

A cytogenetic study of 74 nasopharyngeal carcinoma biopsies.

Cells from 102 nasopharyngeal biopsies of patients suspected of Nasopharyngeal Carcinoma (NPC) and family members of NPC patients were cultured. Metaphases were successfully obtained from 74 of the biopsies of which 52 were subsequently histologically confirmed to be NPC. Cytogenetical analysis using Q-banding showed abnormalities in 15 cultures, and these included polyploidy, aneuploidy and marker chromosomes. Of the 15 abnormal cultures, 14 were from confirmed NPC patients and in five of these, a consistent 5q+ abnormally was seen involving 5q31. The only other abnormal chromosome changes seen was in a patient with olfactory neuroblastoma.

Asia, Southeastern↗
PubMedDate not supplied

[New aspects of the biology of Entamoeba histolytica].

To determine the mechanism of mitosis in E. histolytica, a study was carried out with axenic cultures of trophozoites in Coplin jars with glass slides to stain them in situ with Giemsa and fluorescent antibodies for actin. Tobuline and myosin. Sedimented amoeba of cultures were used also for ultrastructural studies after glutaraldehyde fixation, and inclusion in spon-araldite. Giemsa stained trophozoites showed duplication by budding or fission with production of polykaryons, mononuclei, micronuclei and apparent polyploidy and DNA reduction. Tubuline was present in nuclei and cytoplasm, actin and myosin had a peripheral distribution with low contents of the latter in large amoeba, resulting in polynucleated cells. The findings are suggestive of endomeiosis with chromosomal recombination which would render virulent and non virulent strains producing either invasive or asymptomatic amoebiasis.

Animals↗
PubMed1991

Intrinsic factors involved in vascular smooth muscle cell proliferation in hypertension.

The exaggerated response to growth factors of vascular smooth muscle cells from spontaneously hypertensive rats when compared to cells from normotensive control Wistar-Kyoto rats persists in culture, indicating an intrinsic/genetic defect. The time course of 3H-thymidine incorporation shows that synchronized vascular smooth muscle cells from spontaneously hypertensive rats start to synthesize new DNA earlier after mitogenic stimulation than cells from normotensive rats. Flow cytometry demonstrates that in cell populations growing in 10% calf serum for three d there is a higher proportion of cells from spontaneously hypertensive rats in the S phase of the cell cycle. The same proportions in the G2 + M phase of growing, as well as synchronized cells from normotensive and hypertensive rats indicate no difference in polyploidy. Forward light scatter analysis reveals no difference in cell size. These results suggest that the growth kinetic of vascular smooth muscle cells from normotensive and spontaneously hypertensive rats are different. Since the defect seems to be in the prereplicative phase of the cell cycle susceptible to regulation by extrinsic factors, we studied the effect of the calmodulin inhibitor, W-7, on DNA synthesis. The comparable IC50 of W-7 to inhibit cell growth of vascular smooth muscle cells of both origins indicates that the defect may not be due only to calmodulin, and furthermore suggests the involvement of a previously-reported calmodulin activator in hypertension.

Animals↗
PubMed1991

Flow cytometric DNA analysis of poorly differentiated adenocarcinoma of the colorectum.

DNA ploidy patterns in 11 poorly differentiated adenocarcinomas of the colorectum were examined by flow cytometry using paraffin-embedded specimens. Measurements of DNA content were made of the superficial (Sup) half and deeper (Deep) half of the primary tumors in all cases, and of lymph node metastases in five cases. All the primary tumors showed invasion beyond the muscularis propria of the colorectum. Aneuploidy or polyploidy in either Sup or Deep of the primary tumor was found in six of the 11 (54.5%) tumors. Out of the six aneuploid tumors, five were in Dukes' stage C with distant metastases at the time of operation, and four died within one year of surgery. Conversely, out of five diploid tumors, none had distant metastases at the time of operation and two survived for longer than three years after surgery. The DNA ploidy pattern of Deep differed from that of Sup in four out of six aneuploid tumors, and two showed aneuploidy in Sup and diploidy in Deep. All the lymph node metastases in the five tumors had a diploid pattern, although three had aneuploid patterns in the primary tumors. The findings suggest the DNA ploidy pattern of a primary tumor to be correlated with the degree of metastasis at the time of operation or prognosis, but the population of tumor cells having different DNA contents may be apt to change between Sup and Deep in aneuploid tumor.

Adenocarcinoma↗
PubMed1976

Clinical aspects of dental anomalies.

Many inherited disorders have oral manifestations which can be detected on dental radiographs as alterations in the morphology or chemical composition of the teeth. Thus the dentist may be the first to detect disorders of development and metabolism of importance to the general health of the patient and his family. In one group of conditions the pulp chamber is larger than normal. This may be associated with taurodontism in such conditions as polyploidy of the -X chromosome and trisomy-21 or Down's syndrome. Taurodontism also occurs in a variety of other syndromes including the tricho-dento-osseous syndrome described by Robinson, Miller and Worth (1966) and Mohr's syndrome. It may also be associated with scanty hair endoligodentia. In certain metabolic conditions the pulp chamber may be enlarged but the teeth are of relatively normal from (cynodont). Such cases include hypophosphatemic vitamin D-resistant and dependent rickets, pseudo-hypoparthyroidism otodental syndrome and hypophosphatasia. Small pulp chambers and associated anomalies of root morphology also occur in hereditary disorders either alone or as part of various syndromes such as dentino-osseous dysplasia and brackioskeletogenital syndrome. Dentinogenesis imperfecta may occur alone or as one manifestation of osteogenesis imperfecta. Other developmental defects including pulpal dysplasia, labodontia and dens invaginatus are also associated with small pulp chambers.

Bone Diseases, Developmental↗
PubMedDate not supplied

[The value of placental histology for the detection of genetically-induced abortions].

The majority of early spontaneous abortions is caused by genetic disorders. Chromosomal aberrations do not only imply characteristical morphologic alterations in embryo/fetus, but also in chorionic villi. Its possible to draw conclusions through the combination of a small amount of histological findings on chorionic villi to explain the kind of aneuploidy. Among 968 early spontaneous abortions 18.3% were defined as genetically caused by histological examination. 87.6% are probably trisomies, 7.3% polyploidies. 5.1% were diagnosed as complete hydatidiform moles with a diploid, androgenetic chromosome set. The value of histological examination of early spontaneous abortion tissue are discussed and it is pointed out to remaining problems. In a different percentage it is possible to establish the type of aneuploid by microscopic examination alone. Frequently there are sings to allow the conclusion there is a developmental disorder like genetic aberration.

Abortion, Incomplete↗
PubMed1991

A cytogenetic study of spontaneous abortions with direct analysis of chorionic villi.

The karyotypes of 144 spontaneous abortuses were determined using direct chromosome preparations from chorionic villi. The frequency of chromosome abnormality was 69.4%, which is considerably higher than figures cited in most previous cytogenetic surveys using the conventional method of cell culturing. Autosomal trisomy was the predominant abnormality (64%), followed by polyploidy (9%), monosomy X (7%), structural rearrangements (6%), mosaicism (6%), double trisomy (4%), and double chromosome anomaly (3%). Direct preparations have advantages in that results can be obtained rapidly, the success rate of karyotyping is satisfactory, and maternal-cell contamination is minimal.

Abortion, Spontaneous↗
PubMed1990

[DNA determination by cytophotometry in bowenoid papules in comparison with condylomata acuminata and Bowen's disease].

The relation between bowenoid papules and Bowen's disease is characterized by largely corresponding histological pictures and diverging clinical-epidemiological features. In bowenoid papules and Bowen's disease, 5 cases each, compared with 5 cases of common condylomata acuminata, we determined the DNA by means of Feulgen's cytophotometry in visible light after Feulgen's staining. The following results were obtained: The average DNA content in bowenoid papules equals that in Bowen's disease, but it is significantly higher than in condylomata acuminata. What is different between the two groups "bowenoid papules" and "Bowen's disease" is the distribution of DNA: In Bowen's disease, DNA spreads into higher ranges of polyploidy. If we take recent molecular biological/virological findings into account, this result can be interpreted as a transition towards carcinoma in situ.

Adult↗