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PubMed1985

DNA content and chromosomal composition of malignant human gliomas.

A short review is given on DNA aberrations and chromosomal composition of malignant human gliomas. By flow cytometric DNA analysis, a wide range of different ploidies has been reported in biopsied gliomas, from diploid to strongly aneuploid nuclear DNA. However, with the preparation and analysis methods used so far, no clear relationship between the type of ploidy and histology or prognosis has been established. A high proportion of glioblastomas is near-diploid, indicating a high degree of biologic malignancy is not necessarily connected to aberration of the nuclear DNA content. It is possible that improved methods giving a higher degree of resolution will allow separation of the near-diploid populations of malignant human gliomas from normal diploid cells and permit the detection of subpopulations with small differences from the dominant DNA mode. Chromosomal studies of malignant gliomas have confirmed that the majority of them have near-diploid stemlines. These populations are seldom normal diploid, however, as both numerical and structural abnormalities are usually present. In addition, chromosomal analyses have shown that when gliomas are bimodal, the polyploid populations are usually doubled versions of the near-diploid ones. In contrast to the near-diploid populations that characterize biopsied malignant gliomas, both FCM studies and karyotyping have demonstrated that permanent cultured cell lines derived from malignant gliomas are usually near-triploid or near-tetraploid. Sequential karyotypic studies of these tumors from biopsy through establishment in vitro have shown an evolutionary pattern consisting of doubling of the original stemline, followed by gains or losses of individual chromosomes with new marker formation in late culture. Evaluation of biopsied malignant gliomas by karyotyping has also demonstrated that subgroups of them are characterized by specific numerical and structural deviations. These groupings may prove useful in predicting prognosis or responsiveness to specific therapeutic regimens. The specific chromosomal abnormalities observed in malignant human glioma may provide clues as to the genes important in glial transformation. As chromosomal loci for production of structural proteins and enzymes involved in glial metabolism are mapped and patterns of oncogene activation and amplification are determined for human gliomas, the meaning of the nonrandom chromosomal changes seen in these tumors may become clear.

Adult↗
PubMed2004

Gene amplification as a developmental strategy: isolation of two developmental amplicons in Drosophila.

Gene amplification is known to be critical for upregulating gene expression in a few cases, but the extent to which amplification is utilized in the development of diverse organisms remains unknown. By quantifying genomic DNA hybridization to microarrays to assay gene copy number, we identified two additional developmental amplicons in the follicle cells of the Drosophila ovary. Both amplicons contain genes which, following their amplification, are expressed in the follicle cells, and the expression of three of these genes becomes restricted to specialized follicle cells late in differentiation. Genetic analysis establishes that at least one of these genes, yellow-g, is critical for follicle cell function, because mutations in yellow-g disrupt eggshell integrity. Thus, during follicle cell differentiation the entire genome is overreplicated as the cells become polyploid, and subsequently specific genomic intervals are overreplicated to facilitate gene expression.

Animals↗
PubMed2026

A spatiotemporal resolution to genetic redundancy: MIR164 diversification coordinates development and metabolism in Brassica.

Whole-genome duplication (WGD) events create genetic redundancy, posing the evolutionary challenge of how paralogs escape functional overlap to drive innovation. Here, we demonstrate that the MIR164 family in Brassica oleracea resolves this redundancy through spatiotemporal niche partitioning. Following WGD, the family expanded to eight members, which subsequently underwent divergent selection-some preserved under purifying selection, while others showed signals of positive selection. This led to expression divergence, with Bol-MIR164a1 emerging as a key universally expressed paralog. CRISPR-Cas9 mutagenesis of Bol-MIR164a1 revealed its essential role in coordinating two pivotal traits: leaf serration and leaf coloration. Mutants exhibited enhanced leaf serration due to spatial deregulation of CUC2 at organ boundaries, concurrently with yellow-green leaves and elevated flavonoid accumulation. We mechanistically linked the metabolic phenotype to direct transactivation of the anthocyanidin reductase (ANR) promoter by NAC100, alongside its upregulation of chlorophyll catabolism genes. Our findings establish a paradigm in which spatial segregation of target gene expression domains enables a single, widely expressed miRNA paralog to resolve genetic redundancy by independently orchestrating distinct regulatory programs. This provides a fundamental framework for understanding complex trait evolution in polyploids. This allows a single miRNA locus to independently orchestrate both morphological patterning and metabolic programming, providing a fundamental framework for understanding complex trait evolution in polyploid crops.

MicroRNAs↗
PubMed2006

[Human large intestine adenocarcinoma cells (CaCo-2) in the process of cultivation].

Using cytomorphometry and cytophotometry cells of human large intestine adenocarcinoma (CaCo-2) were studied under condition of a 10 day cultivation. A reverse dependence was established between proliferative activity and monolayer density. The increase of the latter inhibits proliferation and promotes the formation of islets of polymorph cells. 2c-cells could be seen only at the beginning of culture growth; a larger part of cells polyploidized by cell blocking in G2-phase. These cells do not divide, which is testified by the absence of 2c-cells, but some part of 4c-cells start the next cycle, accumulates 8c-DNA and then divides, replenishing the 4c-cells population. In the process of cultivation, we observed an increase in the number and total volume of nucleoli in the nuclei, and a rise in DNA amount in the peri-nucleolar chromatin. The formation of numerous 4c-cells with multi-nucleolar nuclei may define an increase of functional activity of CaCo-2 culture as the whole, whereas the formation of separated groups of such cells in the monolayer may denote a possible initiation of their differentiation.

Caco-2 Cells↗
PubMed1988

MCA/MR syndrome in a female infant with tetraploidy mosaicism: review of the human polyploid phenotype.

We report on a 3-month-old girl with unusual facial appearance, short neck with low posterior hairline, wide chest, valvular pulmonic stenosis, abnormal fingernails, and diploid-tetraploid mosaicism (46,XX/92,XXXX in 7.2% of peripheral leucocytes and in 29% of skin fibroblasts). Comparison with 11 previously reported cases with mosaic or complete tetraploidy does not establish an easily recognizable syndrome. However, a malformation pattern is apparent when tetraploidy patients are compared with 14 cases of triploid mosaicism and 44 previously reported cases of nonmosaic triploidy. A history of sex hormone exposure was present in 5 of 11 pregnancies resulting in tetraploidy; this exposure may correlate with the occurrence of tetraploidy in polycystic ovary syndrome and in tumors of the female reproductive tract. The mechanism of dysmorphogenesis involved in polyploidy is considered, including hypotheses of altered nuclear/cytoplasmic ratio, of trophoblastic alteration, of delayed cell division, or of altered autosome/active X chromosome ratio.

Abnormalities, Multiple↗
PubMed2006

The selective continued linkage of centromeres from mitosis to interphase in the absence of mammalian separase.

Separase is an evolutionarily conserved protease that is essential for chromosome segregation and cleaves cohesin Scc1/Rad21, which joins the sister chromatids together. Although mammalian separase also functions in chromosome segregation, our understanding of this process in mammals is still incomplete. We generated separase knockout mice, reporting an essential function for mammalian separase. Separase-deficient mouse embryonic fibroblasts exhibited severely restrained increases in cell number, polyploid chromosomes, and amplified centrosomes. Chromosome spreads demonstrated that multiple chromosomes connected to a centromeric region. Live observation demonstrated that the chromosomes of separase-deficient cells condensed, but failed to segregate, although subsequent cytokinesis and chromosome decondensation proceeded normally. These results establish that mammalian separase is essential for the separation of centromeres, but not of the arm regions of chromosomes. Other cell cycle events, such as mitotic exit, DNA replication, and centrosome duplication appear to occur normally. We also demonstrated that heterozygous separase-deficient cells exhibited severely restrained increases in cell number with apparently normal mitosis in the absence of securin, which is an inhibitory partner of separase.

Animals↗
PubMedDate not supplied

Annulate lamellae in a large cell lung carcinoma cell line with high expression of tyrosine kinase receptor and proto-oncogenes.

The morphology, karyotype, in vitro growth properties, and expression of tyrosine kinase receptors and proto-oncogenes are reported for a newly established large cell undifferentiated lung carcinoma cell line (RVH-6849). The results were analyzed concomitantly with those for two well-established cell lines from an adenocarcinoma of the lung (A549) and a squamous cell carcinoma (A431). All three cell lines demonstrated common ultrastructural features of epithelial cells, but only RVH-6849 had frequent aggregates of centrioles and annulate lamellae (AL) and was polyploid, having five to seven copies of chromosome 7 by karyotype analysis. All three cell lines expressed transforming growth factor alpha (TGF-alpha), epidermal growth factor receptor (EGFR), c-erb B-2, and c-met genes. RVH-6849 cells, however, expressed the most messenger RNA (mRNA) for TGF-alpha, c-erb B-2, and c-met. Only EGFR mRNA was expressed more in the other two cell lines, especially in A431 cells. AL represent an exaggerated form of the nuclear membrane-pore complex that is found in actively proliferating cells such as germ and some neoplastic cells. AL are suspected to be involved in the deposition or processing of mRNA: The enhanced coexpression of AL and mRNAs of three tyrosine kinase-containing receptors in RVH-6849 cells may represent such a relationship.

Blotting, Northern↗
PubMed2006

The puzzle of ploidy of Purkinje neurons.

This paper places attention on the discrepancies existing in the literature on the ploidy of Purkinje neurons and focuses on the special case of partial replication of their genome and on the unequal frequency of polyploid Purkinje neurons in the cerebellar cortex of the lobes and the vermis. Owing to the compartmental structure of the cerebellum, this paper suggests the investigation with modern methods and techniques of other cerebellar regions such as the flocculus, with the aim of establishing whether increased ploidy correlates with cell hypertrophy and/or with stimulation of cerebellar functions.

Aging↗
PubMed2004

Prognostic significance of DNA ploidy and proliferative index (MIB-1 index) in childhood rhabdomyosarcoma.

The prognostic value of DNA ploidy and proliferative index (PI) are well established in many cancers, but their significance in childhood rhabdomyosarcoma (RMS) is unclear. We studied the DNA content and PI of 45 cases of childhood RMS obtained retrospectively. DNA histograms were hyperdiploid in 30 cases (67%), diploid in 6 (13%), tetraploid in 5 (11%), polyploid in 3 (7%), and nonclassifiable in 1 (2%). The 5-year overall survival rate by ploidy was 60% (3/5) in tetraploid, 57% (17/30) in hyperdiploid, and 0% in diploid and polyploid cases (P = .000002). The 5-year overall survival by a PI less than or greater than 19% was 62% (13/21) and 21% (5/24), respectively (P = .006). In multivariate analysis, DNA ploidy (P = .001) was an important independent prognostic factor. DNA content in childhood RMS is an important variable in predicting prognosis. DNA hyperdiploid and tetraploid rhabdomyosarcomas had a favorable prognosis, while DNA diploid and polyploid tumors had a poor prognosis.

Adolescent↗
PubMed1990

Functional control of hepatocyte proliferation. Comparison with the temporal control of cardiomyocyte proliferation.

A 4.1-fold difference in liver weight, a 2.5 fold difference in hepatocyte number, and a 1.5-fold difference in mean ploidy were seen in mice on the day of weaning (day 21) reared four (fast-growing group) or sixteen (slow-growing group) to a litter. These differences in proliferation parameters were eliminated in adult mice that had similar liver weights. The kinetics of the changes were not time dependent, i.e. under temporal control, but corresponded to liver-weight kinetics. The definitive number of hepatocytes was established by 3 weeks of age in the fast-growing mice and by 3 months in the slow-growing ones. In contrast to the hepatocytes, multiplication of heart myocytes of the same mice was inhibited by 3-4 days after birth and polyploidization ceased about 3 weeks after birth in mice from both fast- and slow-growing litters, and a stable (approximately 40%) difference in cardiac myocyte number and ploidy persisted throughout the entire period of ontogenesis. It is concluded that hepatocyte proliferation is under functional control whereas cardiac myocyte proliferation is time dependent. Postmitotic hypertrophy of the cell cytoplasm is functionally dependent in both heart and liver. In slow-growing mice, an increase in heart weight occurs only as a result of cytoplasmic hypertrophy, whereas in the liver, cell number and ploidy are both involved.

Age Factors↗
PubMed2004

Stochastic and epigenetic changes of gene expression in Arabidopsis polyploids.

Polyploidization is an abrupt speciation mechanism for eukaryotes and is especially common in plants. However, little is known about patterns and mechanisms of gene regulation during early stages of polyploid formation. Here we analyzed differential expression patterns of the progenitors' genes among successive selfing generations and independent lineages. The synthetic Arabidopsis allotetraploid lines were produced by a genetic cross between A. thaliana and A. arenosa autotetraploids. We found that some progenitors' genes are differentially expressed in early generations, whereas other genes are silenced in late generations or among different siblings within a selfing generation, suggesting that the silencing of progenitors' genes is rapidly and/or stochastically established. Moreover, a subset of genes is affected in autotetraploid and multiple independent allotetraploid lines and in A. suecica, a natural allotetraploid derived from A. thaliana and A. arenosa, indicating locus-specific susceptibility to ploidy-dependent gene regulation. The role of DNA methylation in silencing progenitors' genes is tested in DNA-hypomethylation transgenic lines of A. suecica using RNA interference (RNAi). Two silenced genes are reactivated in both ddm1- and met1-RNAi lines, consistent with the demethylation of centromeric repeats and gene-specific regions in the genome. A rapid and stochastic process of differential gene expression is reinforced by epigenetic regulation during polyploid formation and evolution.

Arabidopsis↗
PubMed1984

Chromosome segregation from cell hybrids. I. The effect of parent cell ploidy on segregation from mouse-Chinese hamster hybrids.

To determine whether the dosage of some parental factor influences the direction and extent of chromosome segregation, I have constructed hybrids between polyploid series of mouse and Chinese hamster lines. The input ratio of mouse:hamster chromosomes varied from 3.3 (in hybrids between diploid hamster and polyploid mouse cells) and 0.9 (in hybrids between polyploid hamster and near-diploid mouse cells). Mouse chromosomes were retained and hamster chromosomes were lost from all hybrids with input ratios greater than or equal to 1.3; the extent of hamster chromosome loss increased from 25 to 60% as the proportion of mouse chromosomes was increased. Reverse segregation was observed in hybrids in which the ratio was 0.9; hybrids between polyploid hamster and diploid mouse cells retained most hamster chromosomes and lost 52% of mouse chromosomes. I conclude that the direction and extent of chromosome segregation from these hybrids depends on the dosage of some factor contained in the parent cells; because the volumes of polyploid cells are proportional to chromosome number, this factor could be chromosomal, nuclear, or cytoplasmic. Dosage differences should therefore be considered when comparing chromosome segregation from hybrids with cells of the same species combination, but which might differ in chromosome number (e.g., diploid lines and established lines), or cell volume (e.g., cells from different tissues).

Animals↗
PubMed1982

Human chromosome analysis in 24 cases of primary carcinoma of the large intestine: contribution of the G-banding technique.

As in the haemopathies, the application of cytogenetics to epithelial cancers could aid in the study of their pathogenesis evaluation. In this context we performed chromosome analyses on a series of human colo-rectal cancers. The technique was consistently reliable since the modal number of chromosomes could be determined in all 24 cases. In 22, karyotypes could also be established. Each tumour was characterized by a single cell clone in 21 cases and by a mosaic of 2 populations in 3 cases. Numerical anomalies were not due to chance: they enabled near-diploid (11 cases), near-triploid (9 cases), mosaic (3 cases) and highly polyploid (1 case) cancers to be distinguished. Supernumerary chromosomes were primarily in groups C and F. The most frequent markers before denaturation techniques were No 2q +, No F and minutes. Each time double-minutes were observed (5 cases), they were in invasive cancers (B and C Dukes classification). Cells were generally diploid in non-invasive cancers with fewer quantitative and structural anomalies. Tumour cytogenetics were related to the histological type and localization in the colon, as well as to the local and metastatic spread.

Adenocarcinoma↗
PubMed1984

Cytophotometric measurements of the DNA in Hodgkin lymphomas and non-Hodgkin lymphomas.

In smear preparation of lymph nodes excised from 36 patients with a malignant lymphoma the DNA content was estimated in different tumor cells following Feulgen staining by means of quantitative cytophotometric measurements. The tumors investigated included 11 Hodgkin lymphomas and various types of Non-Hodgkin lymphomas (altogether 25). Whereas the small lymphoid cells found in Hodgkin lymphomas show a diploid DNA content with a wide scattering, in the large mononuclear reticular cells (Hodgkin cells) as well as in Sternberg's giant cells only aneuploid DNA values are seen lying in the hyperdiploid, hypertetraploid and hyperoctoploid regions. DNA stemlines are found in the aneuploid regions, but in some cases they are missing. This indicates that we are dealing with malignant tumor cells. In Non-Hodgkin lymphomas with a low grade of malignancy (centrocytic-centroblastic lymphoma, centrocytic lymphoma, CLL) an aneuploid DNA content is found particularly in the large cells (centroblasts, lymphoblasts) with or without a DNA stemline. These cells must be considered as primary malignant tumor cells. In the immunoblastic lymphoma of high malignancy only aneuploid tumor cells are present showing a particularly intense DNA content in the large immunoblasts, whereas a DNA stemline is usually missing. The range of aneuploid values, the number of polyploid tumor cells and the presence or absence of a DNA stemline are important criterions in determining the degree of malignancy. By means of cytophotometric measurements of the DNA content in the tumor cells of malignant lymphomas it is possible to assertain the degree of malignancy and to establish an objective prognosis.

DNA, Neoplasm↗
PubMed2000

Transgene silencing by the host genome defense: implications for the evolution of epigenetic control mechanisms in plants and vertebrates.

Increasing evidence supports the idea that various transgene silencing phenomena reflect the activity of diverse host defense responses that act ordinarily on natural foreign or parasitic sequences such as transposable elements, viroids, RNA and DNA viruses, and bacterial DNA. Transgenes or their transcripts can resemble these cellular invaders in a number of ways, thus making them targets of host protective reactions. At least two distinct host defense systems operate to silence transgenes. One acts at the genome level and is associated with de novo DNA methylation. A second line of defense operates post-transcriptionally and involves sequence-specific RNA degradation in the cytoplasm. Transgenes that are silenced as a consequence of the genome defense are revealing that de novo methylation can be cued by DNA-DNA or RNA-DNA interactions. These methylation signals can be interpreted in the context of transposable elements or their transcripts. During evolution, as transposable elements accumulated in plant and vertebrate genomes and as they invaded flanking regions of genes, the genome defense was possibly recruited to establish global epigenetic mechanisms to regulate gene expression. Transposons integrated into promoters of host genes could conceivably change expression patterns and attract methylation, thus imposing on endogenous genes the type of epigenetic regulation associated with the genome defense. This recruitment process might have been particularly effective in the polyploid genomes of plants and early vertebrates. Duplication of the entire genome in polyploids buffers against insertional mutagenesis by transposable elements and permits their infiltration into individual copies of duplicated genes.

Animals↗
PubMed1991

[The possible cytophotometry of nucleolar proteins. The prospects for research on the status of the nucleolus apparatus].

Possibility of cytophotometry application was established for the acid nucleolar proteins reacting with silver nitrate. The increase in transcription in the Purkinje neurons results in the expansion of the Ag-proteins areas, whereas their amount may be not increased. The amount and area of the Ag-proteins double in hepatocytes through polyploidization, but the number of nucleoli does not correspond to the gene dosage. This lack of correspondence was also revealed in micronucleoli. The number of nucleoli is not similar in the nuclei of some binuclear hepatocytes, and this disproportionality increases through polyploidization.

Animals↗
PubMed2002

Anteroposterior patterning in adult abdominal segments of Drosophila.

The cuticle of the adult abdomen of Drosophila is produced by nests of imaginal histoblasts, which proliferate and migrate during metamorphosis to replace the polyploid larval epidermal cells. In this report, we present a detailed description of the expression of four key patterning genes, engrailed (en), hedgehog (hh), patched (ptc), and optomotor-blind (omb), in abdominal histoblasts during the first 42 h after pupariation, a period in which the adult pattern is established. In addition, we describe the expression of the homeotic genes Ultrabithorax, abdominal-A, and Abdominal-B, which specify the fates of adult abdominal segments. Our results indicate that abdominal segments develop in isolation from one another during early pupal stages, and that some patterning events are independent of hh, wingless, and decapentaplegic signaling. We show that pattern and polarity in a large anterior portion of the segment are specified without input from Hh, and present evidence that abdominal tergites possess an underlying symmetric pattern upon which patterning by Hh is superimposed. The signals responsible for this underlying symmetry remain to be identified.

Abdomen↗
PubMed2025

Genomic analyses of three Acanthus L. species provide insight into polyploidization-driven speciation and evolution.

Allopolyploidy fundamentally influences plant evolution, yet the genomic dynamics of allotetraploidization remain incompletely understood. We investigated Acanthus tetraploideus (2n = 4x = 96), an ecologically significant allotetraploid true mangrove from Indo-West Pacific intertidal zones. Our prior integrative investigations indicate that A. tetraploideus originated through hybridization of the diploid species A. ilicifolius and A. ebracteatus with subsequent chromosome doubling. Here, we present complete chromosome-scale genome assemblies for all three species, representing the first genomic resources for true mangrove polyploid research. Our analysis reveals that the three species have experienced at least four rounds of polyploidization events, with the most recent, approximately 53 mya, possibly an Acanthus-specific event. The allotetraploid A. tetraploideus, which emerged between 1.5 and 2.2 mya, has A. ebracteatus as its maternal progenitor and A. ilicifolius as its paternal one. Through a comprehensive genomic comparison and analysis of homoeologous gene expression, we propose a gradual evolutionary trajectory for allotetraploidy in A. tetraploideus. Despite the allotetraploidization event dating back to around 2 mya, A. tetraploideus retains a high degree of colinearity with its ancestral genomes, with the majority (76.2%) of duplicated genes retained and no significant sub-genome bias in gene expression. Furthermore, we have identified positive selection in specific genes that may facilitate the adaptation of Acanthus mangrove species to their intertidal habitats. These findings establish A. tetraploideus as a model for studying allopolyploid evolution while providing new insights into mangrove speciation processes.

Genome, Plant↗