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PubMed2000

Chromosomal rearrangement in autotetraploid plants of Arabidopsis thaliana.

Recent development of cytogenetic techniques has facilitated significant progress in Arabidopsis thaliana karyotype studies. Double-target FISH with rRNA genes provides makers that allow individual chromosome in the genome to be distinguished. Those studies have revealed that the number and position of rDNA loci is ecotype-specific. Arabidopsis is believed to be a true diploid (x = 5) with numerous ecotypes (accessions) and only a very few natural polyploid populations reported. Few studies were undertaken to induce polyploidy in Arabidopsis, however none of those gave the cytogenetic characteristics of polyploid plants. Our analysis of chromosome pairing of colchicine-induced autotetraploid Arabidopsis (Wilna ecotype) revealed preferential bivalent pairing in PMCs (pollen mother cells). In order to attempt to explain this phenomenon, first of all more detailed cytogenetic studies of autopolyploid plants have been undertaken. The localization of 45S and 5S rDNA loci in the diploid and autotetraploid plants revealed that Wilna ecotypes belongs to the group of Arabidopsis accessions with only two 5S rDNA loci present in a genome. Furthermore, the rearrangement of 45S rDNA locus in autopolyploid, when compared to the diploid plants of the same ecotype, was revealed. These results are interesting also in the context of the recently emphasised role of polyploidy in plant evolution and speciation. Arabidopsis, despite having small chromosomes, is a good system to study chromosome behaviour in relation to diploidization of autopolyploids and to evaluate the degree of chromosomal rearrangements during this process.

Arabidopsis↗
PubMed1997

Numerical chromosomal aberrations in Hodgkin's disease detected by in situ hybridisation on routine paraffin sections.

AIMS: To visualise directly numerical chromosomal aberrations and polyploidy in both Hodgkin and Reed Sternberg (HRS) cells and background cells from cases of Hodgkin's disease using in situ hybridisation. METHODS: Non-isotopic DNA in situ hybridisation was applied to interphase cell nuclei of Hodgkin's disease within routine paraffin embedded tissue sections. Two a satellite DNA probes, specific for chromosomes 3 and 12, were used to evaluate the feasibility of this approach. Double labelling with immunocytochemical detection of the CD30 antigen was used to identify HRS cells. Cytogenetic normal diploid and triploid placental tissue served as controls. RESULTS: The eight cases of Hodgkin's disease investigated displayed frequent polysomy, while the majority of background cells showed disomy signals. CONCLUSIONS: Numerical chromosomal aberrations were detected in HRS cells from eight cases of Hodgkin's disease by in situ hybridisation. These data show that in Hodgkin's disease HRS cells frequently display polyploidy compared with background cells and are, therefore, probably the only neoplastic component in this disease. Correlations between polysomy and tumour type or grade could not be made from these data owing to the limited number of cases examined and to problems with interpreting data from truncated nuclei.

Adolescent↗
PubMed1985

A cytogenetic study of subfertility in the domestic cat (Felis catus).

The chromosomes of cat embryos derived from three subfertile queens were studied 4 weeks postcoitum. The incidence of spontaneous chromosome anomalies was 15% and type of abnormality observed was autosomal mosaicism. The significance of this finding and the developmental fate of the chromosomally aberrant embryos is discussed. The absence of polyploidy and (nonmosaic) autosomal trisomy, which are the most common observations in previous studies on mammalian embryos, suggests that the difference between the present observations and previous studies may be related to the difference in gestational stage studied, or to the difference in ovulatory patterns between domestic cats and other mammals. Polyploidy through ageing of the gametes is less likely in the cat than in spontaneous ovulators since ovulation in cats is induced only after coitus. It is speculated that chromosome analysis of earlier stages of embryonic development may reveal more severe forms of karyotype alteration.

Animals↗
PubMed1999

Ha-ras oncogene effect on DNA content and chromatin supraorganization in benzo[a]pyrene-transformed human breast epithelial cells.

When transfected to benzo[a]pyrene (BP)-transformed MCF-10F human breast epithelial cells (BP1 cell line) the c-Ha-ras oncogene has proven to enhance the neoplastic changes initiated by exposure to BP, giving rise to an aggressive tumorigenic cell line, BP1-Tras. We have previously demonstrated by image analysis that BP affects the DNA content and the chromatin supraorganization of MCF-10F cells. Here Feulgen-stained BP1-Tras cells were studied by image analysis in order to evaluate possible additional changes in DNA content and chromatin texture induced by insertion of the ras oncogene. A high variability in DNA content also including polyploidy or near-polyploidy, and an increase in the packing states of the chromatin which became still condensed in BP1 cells were found in BP1-Tras cells. The results differed from those reported for the BP1-E1 cell line which is also an aggressive tumorigenic cell line, but was attained through progressive passages of BP-transformed cells. It was demonstrated that different patterns of changes in DNA content and chromatin organization may be involved in equally aggressive tumorigenic BP-transformed cell lines originated from the same cell line by different mechanisms.

Benzo(a)pyrene↗
PubMed1992

Detection of cellular proliferation during compensatory renal growth using flow cytometry.

Compensatory renal growth (CRG) consists of cellular enlargement and a small but consistent increase in DNA content. It has been assumed that the increase in total renal DNA content was due to new cell formation, however, the possibility of nuclear polyploidy remained an alternative explanation. To test the hypothesis whether cellular hyperplasia is the cause of the increase in DNA content during compensatory growth after renal deprivation, we performed cell cycle analysis using flow cytometry. Following unilateral nephrectomy, the amount of cortical cells in the S phase increased by 12% at 10 h while the number of cells in the G2M phase increased by 7% at 120 h. Medullary cells entering the S phase increased by 26% at 24 h and those in G2M increased by 12% at 168 h. DNA synthesis and replication occurs during CRG following unilateral nephrectomy as evidenced by an increase in cells entering both the S and G2M phases of the cell cycle. The increase in DNA content during CRG is a result of cellular proliferation and not polyploidy.

Animals↗
PubMed2003

OrthoParaMap: distinguishing orthologs from paralogs by integrating comparative genome data and gene phylogenies.

BACKGROUND: In eukaryotic genomes, most genes are members of gene families. When comparing genes from two species, therefore, most genes in one species will be homologous to multiple genes in the second. This often makes it difficult to distinguish orthologs (separated through speciation) from paralogs (separated by other types of gene duplication). Combining phylogenetic relationships and genomic position in both genomes helps to distinguish between these scenarios. This kind of comparison can also help to describe how gene families have evolved within a single genome that has undergone polyploidy or other large-scale duplications, as in the case of Arabidopsis thaliana - and probably most plant genomes. RESULTS: We describe a suite of programs called OrthoParaMap (OPM) that makes genomic comparisons, identifies syntenic regions, determines whether sets of genes in a gene family are related through speciation or internal chromosomal duplications, maps this information onto phylogenetic trees, and infers internal nodes within the phylogenetic tree that may represent local - as opposed to speciation or segmental - duplication. We describe the application of the software using three examples: the melanoma-associated antigen (MAGE) gene family on the X chromosomes of mouse and human; the 20S proteasome subunit gene family in Arabidopsis, and the major latex protein gene family in Arabidopsis. CONCLUSION: OPM combines comparative genomic positional information and phylogenetic reconstructions to identify which gene duplications are likely to have arisen through internal genomic duplications (such as polyploidy), through speciation, or through local duplications (such as unequal crossing-over). The software is freely available at http://www.tc.umn.edu/~cann0010/.

Animals↗
PubMed1997

Mutation of a gene for a Drosophila kinesin-like protein, Klp38B, leads to failure of cytokinesis.

Mutations in a gene (Klp38B) encoding a novel kinesin-like protein in Drosophila melanogaster lead to the formation of polyploid cells in the larval central nervous system and in the follicle cells of adult egg chambers. Some homozygous mutants survive to adulthood and also exhibit morphological defects indicative of abnormal cell cycle progression, including rough eyes, missing bristles, and abnormal abdominal cuticles. In larval brains, there is no accumulation of mitotic cells and the frequency of anaphase figures is comparable to wild type, suggesting that nuclear division is not affected. Such brains contain polyploid cells with metaphase and anaphase chromosomes associated with bipolar spindles. Such spindles have a number of unseparated centrosomes at their poles reflecting the degree of polyploidy of the cell. Follicle cells frequently contain two nuclei of roughly equal size. Taken together, we conclude that these Klp38B mutations lead to a failure of cytokinesis resulting in polyploidy, and discuss whether or not this is a direct effect of the mutation.

Amino Acid Sequence↗
PubMed2005

Aneuploidy and genetic variation in the Arabidopsis thaliana triploid response.

Polyploidy, the inheritance of more than two genome copies per cell, has played a major role in the evolution of higher plants. Little is known about the transition from diploidy to polyploidy but in some species, triploids are thought to function as intermediates in this transition. In contrast, in other species triploidy is viewed as a block. We investigated the responses of Arabidopsis thaliana to triploidy. The role of genetic variability was tested by comparing triploids generated from crosses between Col-0, a diploid, and either a natural autotetraploid (Wa-1) or an induced tetraploid of Col-0. In this study, we demonstrate that triploids of A. thaliana are fertile, producing a swarm of different aneuploids. Propagation of the progeny of a triploid for a few generations resulted in diploid and tetraploid cohorts. This demonstrated that, in A. thaliana, triploids can readily form tetraploids and function as bridges between euploid types. Genetic analysis of recombinant inbred lines produced from a triploid identified a locus on chromosome I exhibiting allelic bias in the tetraploid lines but not in the diploid lines. Thus, genetic variation was subject to selection contingent on the final ploidy and possibly acting during the protracted aneuploid phase.

Alleles↗
PubMed1999

Mutagenicity tests of 4-phenyl-1,3-dithia-2-thioxo-cyclopent-4-ene.

The mutagenicity of 4-phenyl-1,3-dithia-2-thioxo-cyclopent-4-ene (DT827B) was examined in reverse mutation tests using Salmonella typhimurium and Escherichia coli, in the chromosomal aberration test with Chinese hamster ovary (CHO) cells, and in the micronucleus test using mice bone-marrow. In reverse mutation assay on DT827B according to Ames' method, DT827B was not mutagenic to S. typhimurium or E. coli when tested in dimethylsulfoxide to the limit of its solubility where precipitation occurred. In chromosomal aberration assay using CHO cells, DT827B was not clastogenic to induce structural chromosomal aberration but capable of inducing polyploidy. In micronucleus test, DT827B did not show micronucleus-inducing potential at the maximum dose. In conclusion of the three mutagenicity studies, DT827B was considered to cause no mutagenicity under the conditions used in the present experiments except the increase in polyploidy, which probably is due to a toxic effect of the compound.

Animals↗
PubMedDate not supplied

Atypical carcinoid tumor of the larynx: an immunohistochemical, ultrastructural, and flow cytometric analysis.

The clinicopathologic features, including a detailed immunohistochemical, ultrastructural, and flow cytometric analysis, are described in three cases of atypical carcinoid tumor of the larynx. All patients had metastatic disease within cervical lymph nodes at presentation and eventually developed distant metastases. Special stains revealed focal intracytoplasmic mucin accumulation, and immunohistochemistry showed the tumors to be positive for CAM 5.2, CEA, chromogranin A, and calcitonin. In two cases, double-staining techniques revealed occasional cells that stained for both mucin and chromogranin A. The histochemical and immunohistochemical findings in these two cases were confirmed at the ultrastructural level, with most tumor cells containing many neurosecretory granules. Smaller numbers of cells contained mucin vacuoles and, in occasional cells, both mucin and neuroendocrine granules were identified. The three tumors exhibited positive staining with D07 (anti-p53), and flow cytometric analysis revealed DNA aneuploidy and polyploidy. The double-staining and ultrastructural features indicate that laryngeal atypical carcinoid qualifies for the designation of true amphicrine carcinoma. Further study is necessary to determine whether mutation of the p53 gene is important in the evolution of laryngeal neuroendocrine tumors and whether DNA aneuploidy or polyploidy identifies a subset of these tumors with a poor prognosis.

Aged↗
PubMed1996

[Combined fluorescence in situ hybridization and cytofluorometric analysis of numerical chromosomal aberrations in squamous cell carcinomas of the tongue].

DNA cytofluorometry and fluorescence in situ hybridization (FISH) with centromeric repetitive probes of chromosomes 1, 7, 11, 17, X and Y were used to detect numerical chromosomal aberrations in 13 squamous cell carcinomas of the tongue. In 4 of the 6 DNA-diploid tumors examined, significant numerical aberrations in at least 1 of the chromosomes were detected. The main line of 1 tumor showed trisomy 1 and the other 3 tumors had significant sublines that showed trisomy or monosomy of the 1 or 2 chromosomes examined. No common specific aberrations were detected in these tumors. Cytofluorometrically we found polyploidy in all 4 of the tumors with numerical chromosomal aberrations. These results suggest that subpopulations which are aneuploid at the chromosome level arise preferentially from DNA-diploid tumors with polyploidy before the ploidy of the main line shifts to overt DNA-aneuploidy. In all of the 7 DNA-aneuploid tumors examined, we detected numerical chromosomal aberrations. Most of the aberrations were thought to occur after tetraploidization because a gain in chromosomal copy number including tetrasomy was common. In 3 DNA-aneuploid tumors, however, the main line showed disomy 11, whereas the other chromosomes examined had 3 or more copies. In 1 of the 3 tumors there was a significant subline of monosomy 11. In these 3 tumors disomy 11 may have been preceded by a DNA-diploid stage with monosomy 11 before tetraploidization.

Carcinoma, Squamous Cell↗
PubMed1976

[So-called empty liver cell nuclei in hepato-cerebral dystrophy and other diseases].

The frequency of identification of "empty" nuclei of hepatocytes was investigated in 65 patients (25 patients with hepato-cerebral dystrophy, 18 patients with cirrhosis of the liver, 15 patients with chronic diseases of the extrapyramidal nervous system and other diseases) with the help of fluorescent and electron microscopy, cytophotometric determination of DNA, and on the basks of bioptic material (in 60 patients) and autopsy findings (in 5 cases). The so-called "empty" nuclei of hepatocytes are not specific for hepato-cerebral dystrophy, although in this disease they were observed in a greater number than in other diseases. Their dependence on the degree of portal hypertension and on some endocrine factors was noted. "Empty" nuclei were identified most often in the periportal regions and were characterized by a considerable increase in the volume, invaginations of the membrane, intranuclear inclusions, polyploidy. The study of polyploidy of the ordinary nuclei of hepatocytes in hepatocytes in hepato-cerebral dystrophy, bearing in mind the reduplicated DNA, revealed the predominance of diploid nuclei.

Astrocytes↗
PubMed1999

Cytogeography and chromosome evolution of subgenus Tridentatae of Artemisia (Asteraceae).

The subgenus Tridentatae of Artemisia (Asteraceae: Anthemideae) is composed of 11 species of various taxonomic and geographic complexities. It is centered on Artemisia tridentata with its three widespread common subspecies and two more geographically confined ones. Meiotic chromosome counts on pollen mother cells and mitotic chromosome counts on root tips were made on 364 populations ( = 3.1 plants per population). These population counts are ∼60% of all Tridentatae counts. Some are first records for taxa. The Tridentatae are a polyploid complex (x = 9) with ploidy levels from 2x to 8x, but mostly 2x (48%) and 4x (46%). Polyploidy occurs in nine of the 11 species and in many subspecies as well. Supernumerary or b chromosomes are present only at a low frequency. In the principal species, A. tridentata, 2x plants are larger than 4x ones, which are adapted to drier conditions, probably in consequence of their slower growth rates. Gigas diploidy is a phenomenon shared by some other woody genera, but is in contrast to the gigas polyploid nature of many herbaceous genera. Polyploidy occurs within populations and is essentially autoploid. Hybridization sometimes occurs at taxa interfaces in stable hybrid zones. Stable Tridentatae hybrid zones coupled with the group's inherent propensity for polyploidization has led to the establishment of a geographically and numerically large and successful complex of species.

Journal Article↗
PubMed2000

[Genome multiplication in the trophoblasts and glandular epithelium of endometrium during embryo implantation and placentation of silver fox].

Dynamics of genome multiplication during establishment of interrelations between the trophoblast and the glandular epithelium of endometrium was studied in the course of placenta formation in the silver fox. Endometrium response on the embryo implantation exhibits some features of inflammation. In the course of placenta formation the trophoblast gains access to the endometrial glandular epithelium zone, while the endometrial blood vessels grow the other way into the expanding trophoblast zone. The trophoblast gradually replaces the whole epithelium and part of the stroma of the endometrium, closely adjoining the endometrial vessels but not disrupting them. Cytophometric DNA measurements in the trophoblast nuclei have shown that most of the nuclei are polyploid: predominantly 4c-64c, occasionally 128c and 256c. Polyploidy of the trophoblast may result from various types of polyploidizing mitoses. Cytophotometric DNA measurements in mitotic figures have revealed mitoses with DNA amounts equal to 4c (2n), 8c (4n), and 16c (8n), which indicates that trophoblast cells in the silver fox placenta are able to enter mitosis prior to the octaploid level. Higher degrees of polyploidy in the trophoblast cells may be achieved presumably by endoreduplication. In the silver fox polyploidization of uterine grandular epithelial cells during placentation occurs until the level of 8c. Thus, the tissue-specific response of the uterus to the implanting embryo is an active proliferation and polyploidization of the glandular epithelium, rather than formation of a population of polyploid decidual cells (i.e. connective tissue cells). Using the silver fox endotheliochorial placenta as an example, a regularity has been confirmed that cells of both maternal and fetal origin are polyploid in sites of their contact in placenta, which might be of protective significance in the contact of allogenic organisms.

Animals↗
PubMed2001

Phylogenetic relationships and evolution of Crassulaceae inferred from matK sequence data.

Chloroplast gene matK sequence data were used to estimate the phylogeny of 112 species of Crassulaceae sampled from 33 genera and all six recognized subfamilies. Our analyses suggest that five of six subfamilies recognized in the most recent comprehensive classification of the family are not monophyletic. Instead, we recovered a basal split in Crassulaceae between the southern African CRASSULA: clade (Crassuloideae) and the rest of the family (Sedoideae). These results are compatible with recent studies of cpDNA restriction site analyses. Within Sedoideae, four subclades were also recovered: KALANCHOE:, Leucosedum, Acre, and AEONIUM:; evidence also exists for a TELEPHIUM: clade and SEMPERVIVUM: clade. The genus SEDUM: is highly polyphyletic with representatives spread throughout the large Sedoideae clade. Sympetaly and polymerous flowers have arisen multiple times in Crassulaceae and thus are not appropriate characters upon which to base subfamilial limits, as has been done in the past. One floral character, haplostemy, appears to be confined to the well-supported CRASSULA: clade. Our analyses suggest a southern African origin of the family, with subsequent dispersal northward into the Mediterranean region. From there, the family spread to Asia/eastern Europe and northern Europe; two separate lineages of European Crassulaceae subsequently dispersed to North America and underwent substantial diversification. Our analyses also suggest that the original base chromosome number in Crassulaceae is x = 8 and that polyploidy has played an important role in seven clades. Three of these clades are exclusively polyploid (SEMPERVIVUM: clade and two subclades within the KALANCHOE: and AEONIUM: clades), whereas four (Crassula, Telephium, Leucosedum, and ACRE: clades) comprise both diploid and polyploid taxa. Polyploidy is particularly rampant and cytological evolution especially complex in the ACRE: clade.

Journal Article↗
PubMed2001

Cell cycle attenuation by p120E4F is accompanied by increased mitotic dysfunction.

In addition to their well-established roles at the G1-S checkpoint, recent reports support a role for universal cyclin-dependent kinase (CDK) inhibitors in the control of G2-M and suggest that their induction may stimulate the occurrence of endomitosis or polyploidy in a number of physiological settings. In this report, the stable expression of the p120E4F transcription factor, which attenuates G1-S progression by elevating p21WAF1 and p27KIP1 protein levels, was shown to also interfere with the regulation of G2-M and cytokinesis. Exponentially growing cultures of p120E4F-expressing fibroblast cell lines had reduced levels of CDC2 kinase activity, elevated levels of Cyclin B1 protein, and continuously generated a subpopulation of tetraploid cells and elevated numbers of multinucleated cells. Coexpression of activated Ras, which stimulates Cyclin D1 expression and G1-S-specific cyclin-CDK kinase activities, alleviated these effects without reducing p21WAF1 or p27KIP1 protein levels; p120E4F/ras-expressing cell lines contained reduced levels of Cyclin B1 protein, a restoration of Cyclin B-CDC2 kinase activity to control levels, and exhibited no increase of tetraploid or multinucleated cells. Interestingly, changes in the expression of Cyclin B1 and, to a lesser extent, CDC2 were primarily regulated by post-transcriptional mechanisms. The results indicate that mechanisms which moderately elevate CDK inhibitor levels can reduce CDC2 kinase activity to the point of impeding normal G2-M function and suggest that two molecular determinants commonly associated with the induction of polyploidy in a number of tissues, i.e., elevated levels of universal CDK inhibitors and sustained CDK2 kinase activity, may be solely sufficient to initiate endomitosis.

3T3 Cells↗
PubMed2002

Recovery of liver mass without proliferation of hepatocytes after partial hepatectomy in Skp2-deficient mice.

The abundance of p27(Kip1), an inhibitor of cell proliferation, is determined by Skp2-dependent proteolysis, the deregulation of which is associated with cancer progression. Lack of Skp2 results in p27(Kip1) accumulation as well as enlargement and polyploidy of hepatocytes. The role of Skp2 in cell growth and proliferation was investigated in Skp2-deficient mice subjected to partial hepatectomy. Skp2(-/-) mice exhibited restoration of liver mass without cell proliferation; rather, hepatocytes increased in size, an effect that was accompanied by increased polyploidy and p27(Kip1) accumulation. Lack of Skp2 thus impairs hepatocyte proliferation, which is compensated for by cellular enlargement, during liver regeneration.

Animals↗
PubMed1975

[Relative concentration of deoxyribonucleic acid in the experimental deciduoma and the blastocyst of female rats: cytophotometric study].

Polyploidy level of experimentally induced deciduomata was determined by cytophotometric measures of DNA-Feulgen, with the "Ultramikrospektrophotometer UMSP Zeiss" by scanning. The antimesometrial tissue reached 32 n, 72 H after the uterine trauma, whereas the mesometrial part did not exceed a 4 n polyploidy level. With the same technics we studied the ovarian hormone, its action upon the blastocyst cellular cycle. In delayed blastocysts, synthesis was never found. OEstradiol removed the inhibition and DNA synthesis then starts again.

Animals↗