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PubMed1984

Nuclear chromatin changes in hepatocytes of soman treated rats.

Cytochemical and morphometric indices of DNA metabolism and nuclear transcriptional-translational capabilities were used to monitor liver responses in Sprague-Dawley X Wistar rats subcutaneously injected with 0.9 LD50 soman, a highly toxic acetylcholinesterase-inhibiting organophosphate. Thirty minutes post-soman the following were evident: (1) increased polyploidization; (2) expansion of the nuclear envelope; and (3) elevated deoxyribonucleoprotein (DNP) complex lability to acid hydrolysis. Nuclear changes were accompanied by cytoplasmic correlates of impaired hepatocyte function, i.e., vacuolation and depressed basophilia. The overall data suggest that with acute soman toxication there are concomitant adaptive and maladaptive responses occurring within liver parenchymal elements. It is postulated that nuclear changes represent an early proliferative response and DNP activation to enhance detoxification capabilities, whereas cytoplasmic changes reflect the disruption of normal function and hepatotoxic injury.

Animals↗

PubMed1990

Different response of cellular DNA content to cardiac hypertrophy in human and rat heart myocytes.

1. Rat and human heart myocytes adapt to overload-induced hypertrophy differently. 2. Human myocyte nuclei respond with polyploidization and multinucleation, thus increasing the DNA content per myocyte from 20 to 40 pg. As a result, nuclear DNA content per 10,000 microns3 of cell volume decreases from 12 to 10 pg. 3. In rat hearts with aortic constriction nuclear DNA content remains constant (13 pg), and the DNA content per 10,000 microns3 of myocyte volume falls from 9 to 6 pg. 4. We hypothesize that "dilution" of nuclear DNA in the hypertrophied rat heart myocyte limits the capacity to hypertrophy (much less than 100%). 5. The human heart myocyte, which is able to compensate for dilution of nuclear DNA, may increase in size more than three-fold. 6. The lower limit of DNA content per unit of myocyte volume is 6 pg/10,000 microns3 in both species.

Animals↗

PubMed1975

Nuclear characteristics and phylogeny in the protistan phylum Ciliophora.

Ciliates possess a number of nuclear characteristics which, in combination, are unique among the Protista. Nevertheless, attempts to understand the origin - presumably from a flagellate ancestry - of the Ciliophora as a phylum must be made, as well as efforts to elucidate phylogenetic pathways within the large and diverse assemblage represented by its present-day forms. The macronucleus may provide an important clue to early ciliate phylogeny, since we still have, among extant species, groups of distinct "karyological relicts" exhibiting the very features expected in hypothetical forms corresponding to postulated stages in macronuclear origin and evolution. The relationship of the groups of "relict" species to the predominant polyploid-macronucleate forms, with a direct impact on the classification system as well as ciliate evolution and phylogeny in general, is discussed in some detail. Arguments are presented for taxonomic separation of the relatively primitive homokaryotic and diploid-macronucleate forms, which also share other features in common related to their being members of the interstitial fauna, from the more advanced ciliates. The problem is complicated by the non-nuclear structural complexities of these sand-dwelling forms, apparently secondarily-derived specializations which, by convergence, have come to resemble certain non-homologous features of the allegedly more highly evolved groups.

Biological Evolution↗

PubMed1992

Biodiversity: molecular biological domains, symbiosis and kingdom origins.

The number of extant species of organisms is estimated to be from fewer than 3 to more than 30 x 10(6) (May, 1992). Molecular biology, comparative genetics and ultrastructural analyses provide new insights into evolutionary relationships between these species, including increasingly precise ideas of how species and higher taxa have evolved from common ancestors. Accumulation of random mutations and large macromolecular sequence change in all organisms since the Proterozoic Eon has been importantly supplemented by acquisition of inherited genomes ('symbiogenesis'). Karyotypic alterations (polyploidization and karyotypic fissioning) have been added to these other mechanisms of species origin in plants and animals during the Phanerozoic Eon. The new evolution concepts (coupled with current rapid rates of species extinction and ignorance of the extent of biodiversity) prompted this analysis of the field of systematic biology and its role in the reorganization of extant species into higher taxa. Two superkingdoms (= Domains: Prokaryotae and Eukaryotae) and five kingdoms (Monera = Procaryotae or Bacteria; Protoctista: algae, amoebae, ciliates, foraminifera, oomycetes, slime molds, etc.; Mychota: 'true' fungi; Plantae: one phylum (division) of bryophytes and nine phyla of tracheophytes; and Animalia) are recognized. Two subkingdoms comprise the monera: the great diverse lineages are Archaebacteria and Eubacteria. The criteria for classification using molecular, ultrastructural and genetic data for this scheme are mentioned. For the first time since the nineteenth century, logical, technical definitions for each group are given with their time of appearance as inferred from the fossil record in the primary scientific literature. This classification scheme, which most closely reflects the evolutionary history, molecular biology, genetics and ultrastructure of extant life, requires changes in social organization of biologists, many of whom as botanists and zoologists, still behave as if there were only two important kingdoms (plants and animals).

Animal Population Groups↗

PubMed1979

Duplicate gene expression in tetraploid fishes of the tribe Moxostomatini (Cypriniformes, Catostomidae).

1. Karyotypically tetraploid fishes of the catostomid tribe Moxostomatini were electrophoretically examined to ascertain in the genetic control of 14 enzyme systems (21 loci in dipoid Cypriniformes). 2. The Moxostomatini have become functionally diploid at 50% or more of their loci since the original polyploidization event in the catosomid line. 3. The subgenera Megapharynx and Moxostoma s.s. (genus Moxostoma) are recognized as comprising a single lineage on the basis of synapomorphic diploidization at the G-3-pdh-A locus. 4. Thoburnia s.l. is allied with the genus Hypentelium on the basis of synapomorphic diploidization at the M-Aat-A locus supporting separate generic status for Thorburnia s.l.

Animals↗

PubMed1985

Microspectrophotometric study and kinetics of autogamy during encystment of Tetrahymena rostrata.

The process of autogamy that accompanies encystment in Tetrahymena rostrata was divided into five stages; A: first meiotic division, B: second meiotic division. C: post-meiotic division and fusion of the pronuclei, D: first and second synkaryon's mitosis and E: macronuclear-polyploidization. In this communication the kinetics of these phases is reported. The degeneration of the old-macronucleus begins about the second meiotic division (stage-B), and the development of the new-macronucleus progressively rises during about 15h.

Animals↗

PubMed1991

Variation in radiation sensitivity during the cell cycle of two human squamous cell carcinomas.

Changes in the radiation age response are described in two cell lines derived from human squamous cell carcinomas. A radioresistant tumor cell line, JSQ-3, has a DO of 240 cGy and is polyploid with a DNA content of 2.68. A relatively radiosensitive tumor cell line, SCC-61, has a DO of 126 cGy and has a DNA index of 1.16. Tumor cells were separated and synchronized by centrifugal elutriation; flow cytometry was used to determine cell-cycle parameters and relative synchrony. The radioresistant cell line, JSQ-3B, was found to have twice the number of cells in S-phase than the more sensitive cell line (28% and 13% for JSQ-3B and SCC-61B, respectively). Both cell lines, despite differences in intrinsic radiosensitivity, were most resistant during S-phase (DOs of 258 and 157 cGy for JSQ-3B and SCC-61B, respectively) and were maximally sensitive during G1 (DOs of 193 and 95 cGy for JSQ-3B and SCC-61B, respectively). Clinical implications of our findings are discussed.

Carcinoma, Squamous Cell↗

PubMed1986

An efficient chloramphenicol-resistance marker for Saccharomyces cerevisiae and Escherichia coli.

Chloramphenicol (Cm) was demonstrated to be a suitable selective agent for the plasmid-mediated transformation of haploid and polyploid strains of Saccharomyces cerevisiae. A yeast/Escherichia coli shuttle Cm-resistance (CmR) marker was constructed by inserting the CAT coding sequence from Tn9, and its associated bacterial ribosome-binding site, between a modified yeast ADC1 promoter and CYC1 terminator. When present on a 2 microns-based replicating plasmid, this marker transformed yeast as efficiently as the auxotrophic markers TRP1 and LEU2. When included in an integrating vector, single-copy transformants were formed as efficiently as with LEU2 and HIS3. Industrial yeast strains were transformed with both the replicating and integrating plasmids. The CmR marker could also efficiently transform E. coli. This versatile and efficient performance is currently unique for a yeast dominant marker.

Acetyltransferases↗

PubMed1985

The control of cell mass and replication. The DNA unit--a personal 20-year study.

The deoxyribonucleic acid (DNA) is constant per cell in diploid tissues and in polyploid tissues the DNA content and the cytoplasm increase commensurately. In muscle the DNA unit (protein/DNA) was described on the assumption that each nucleus has jurisdiction over a certain volume of cytoplasm. Such an approach allows a sensible interpretation of metabolic data. Since 66-70% of nuclei are within myofibres muscle represents a reasonably homogeneous tissue. A brief historical review is made concerning the use of DNA as a cell constant. The application of this knowledge to normal human somatic growth and to disease states is considered as well as reduced nutrition and overnutrition. The consequences of reduced nutrition as it related to brain growth are briefly mentioned as is our 7 year study on the fetal primate (Macaca mulatta). Attention is focussed on our work in the early 1960's concerning the role of insulin and growth hormone on the DNA unit. In the last decade this work culminated in the close study of the Little Mouse with isolated growth hormone deficiency--thus exposing the panhypopituitary model (the human pituitary dwarf, Snell Smith mouse or hypophysectomised rat) as non-optimal models. The findings indicate that growth hormone is indeed related to cell replication and insulin to cytoplasmic growth in the postnatal period but the role of other hormones is clearly important, augmenting or opposing these hormones. The concept of constant change of the DNA unit not only applies to major tissues such as muscle but to the study of kidney growth when the contralateral kidney is removed (renal compensatory growth). Species differences are noted in the pattern of cell growth in muscle, but emphasis is placed on cell replication rather than on cytoplasmic growth in the primate. Restriction of protein energy metabolism mainly affects cytoplasmic growth of muscle but restoration of growth to expected levels is the rule. Overnutrition and obesity relate to excessive growth of DNA units in number rather than size. Attention is drawn to factors other than calories, proteins and hormones that influence hormonal actions viz. trace metals such as zinc, chromium and vanadium. The cell mass of the body can readily be reached by relatively non-invasive methods and by monitoring the intracellular water. Muscle mass can be precisely measured by creatinine excretion. The cell mass of muscle constitutes 70% of the entire cell mass.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1996

Variations of hepatic antioxidant systems and DNA ploidy in rats aged 2 to 8 months.

Oxygen-reactive species are by-products of biological redox reactions and are involved in the development and aging processes. In order to test whether the time-dependent changes in the hepatic antioxidant defense are related to changes in DNA ploidy, we studied in rats, aged 2-8 months, the enzymes and metabolites related to the primary cell defense against oxidative stress, as well as the distribution of DNA into the cell cycle phases. Catalase and glutathione peroxidase, together with glutathione reductase and mitochondrial superoxide dismutase, underwent progressive and significant time course increases. Although no temporal changes were observed in the concentration of protein thiol groups and malondialdehyde in rats in the same age period, glutathione redox state, detected by the GSH/GSSG ratio decreased significantly to 41% (P<0.001) of the initial value. DNA content was assayed by flow cytometry in isolated hepatocytes, and changes in DNA ploidy and distribution in the cell cycle phases were determined. A sharp decrease in diploid population from rats aged 1-8 months (92.9% --> 11.1%) and a pronounced increase in hepatocyte polyploid populations in the same age period (2.6% --> 87.3%) were observed. However, liver cell population involved in S phase (DNA synthesis) was unchanged. These results indicate that the cell defense mechanisms against oxygen toxicity increased in liver of rats from 2-8 months in order to suppress the oxidative imbalance. During the 6-month period of a rat's life (2-8 months), the significant alterations of GSH/GSSG ratio to a more oxidative state have no influence on the proliferating capacity of the cells.

Aging↗

PubMed1995

Relationship between morphological classification of the degree of maturation and the ploidy of micromegakaryocytes in myelodysplastic syndrome patients.

To clarify the biological behavior of micromegakaryocytes in myelodysplastic syndrome (MDS), the relationship between the morphological classification and the ploidy of megakaryocytes was studied in bone marrow aspirates obtained from patients with MDS and from normal controls. The morphology was determined according to Feinendegen's classification, which is considered to reflect megakaryocytic maturation, and the ploidy was determined by microcytofluorometry, using 4',6-diamidino-2-phenylindole (DAPI) staining after the removal of Wright-Giemsa stain. Most micromegakaryocytes (i.e., megakaryocytes < 20 microns in diameter) in MDS were morphologically mature, as were those in the normal controls. The peak micromegakaryocytic ploidy was 4N or 8N, whereas that of the megakaryocytes in normal controls was 16N. These findings indicated that the micromegakaryocytes in MDS were morphologically mature but had impaired polyploidization.

Adult↗

PubMed1993

Linear DNA of Borrelia species and antigenic variation.

Members of the genus Borrelia may be unique among prokaryotic organisms in having a polyploid genome that is mostly linear. The smaller linear duplex replicons in these organisms have been called plasmids, but there is justification for designating them minichromosomes instead. The antigenic identities of the agents of Lyme disease and relapsing fever are largely determined by these extrachromosomal genes.

Antigenic Variation↗

PubMed2006

RUNX1 suppression induces megakaryocytic differentiation of UT-7/GM cells.

The transcription factor RUNX1 plays a crucial role in hematopoiesis. RUNX1 regulates both differentiation and proliferation of hematopoietic cells. Several reports have shown that RUNX1 participates in megakaryopoiesis, which is a process that leads to formation of platelets. However, to date, the mechanisms by which this occurs have not been fully elucidated. In the present study, we investigated whether siRNA-mediated depletion of RUNX1 affected megakaryopoiesis of UT-7/GM cells. The depletion of RUNX1 in UT-7/GM cells resulted in up-regulation of the expression of megakaryocytic markers and polyploidization, while cell proliferation was down-regulated. Furthermore, the overexpression of RUNX1 decreased the activity of megakaryocytic gene promoters. These results suggest that RUNX1 down-regulates terminal differentiation of megakaryocytes and promotes proliferation of megakaryocytic progenitors.

Cell Differentiation↗

PubMed2005

Tangutorine induces p21 expression and abnormal mitosis in human colon cancer HT-29 cells.

A novel beta-carboline alkaloid, tangutorine (benz[f]indolo[2,3-a]quinolizidine) was isolated from the leaves of Nitraria tangutorum L. [Duan JA, Williams ID, Che CT, Zhou RH, Zhao RH, Tangutorine: a novel beta-carboline alkaloid from Nitraria tangutorum. Tetrahedron Lett 1999;40:2593-6], and its unique structural characters led us to initiate a study of its potential anti-proliferation activity. The in vitro treatment with low doses of tangutorine slightly stimulated the proliferation of human colon cancer HT29 cells until at concentrations higher than 6.25 microg/ml when the cell numbers, cellular MTT reduction, and cell proliferation by 3H-thymidine incorporation decreased in a dose-dependent manner (IC50=15 microg/ml=48 microM). Morphological studies of cells by fluorescence and electron microscopy did not show features for apoptosis but only large vacuoles, swollen mitochondria and dense cytoskeletal filaments bunching in the cytoplasm. Immunoblotting analysis revealed a dramatic induction of cyclin kinase inhibitor p21 as well as an inhibition of topoisomerase II expression at 25 microg/ml tangutorine, thereby impeding cell progression from S to G2/M phase. Cells accumulated at G1 phase of the cell cycle at concentrations > or =50 microg/ml tangutorine. Interestingly, some cells escaped from prolonged growth arrest without cell division and resulted in binucleated and polyploid G1 cells. Taken all results together, tangutorine induced a p21 suppression of all cyclins and their associated kinases, such as the topoisomerase II, and thus inhibited normal DNA replication and mitosis.

Carbolines↗

PubMed2006

Metaphase arrest and cell death induced by etoposide on HeLa cells.

DNA damage, cell cycle and apoptosis form a network with important implications for cancer chemotherapy. Dysfunctions of the cycle checkpoints can allow cancer cells to acquire drug resistance. Etoposide is a well-known inducer of apoptosis, which is widely used in cell biology and in clinical practice. In this work we report that a pulse of 50 microM etoposide (incubation for only 3h) on HeLa cells causes a sequence of events that leads to abnormal mitotic figures that could be followed either by cell death or, more commonly, by interphase restitution and endocycle. The endocycling polyploid cells enter immediately into mitosis and suffer metaphase blockage with multiple spindle poles, which were generally followed by a direct triggering of apoptosis from metaphase (mitotic catastrophe), or by a new process of endocycling, until surviving cells finally became apoptotic (96 h after the treatment).

Antineoplastic Agents, Phytogenic↗

PubMed2004

Wilms tumors develop through two distinct karyotypic pathways.

Wilms tumor is an embryonic neoplasm characterized by a large variation in histologic patterns. Cytogenetic investigations have identified nonrandom chromosomal changes characteristic for this tumor type, of which numerical changes, mostly trisomies for chromosomes 7, 8, and 12, are particularly frequent. Despite the abundance of cytogenetic information, with more than 350 published karyotypes, very little is known about the mode of karyotypic evolution. In this investigation, we have used 355 karyotypes of Wilms tumor to identify frequent imbalances. The most frequent were +1q, +6, +7q, +8, +12, +13, -11, and -16. Tumor cases were then classified with respect to the presence or absence of these imbalances and statistically analyzed to assess the order of appearance of chromosomal imbalances, as well as possible karyotypic pathways. We show that Wilms tumors develop through one major mode of karyotypic evolution, common to both low- and high-complex tumors, and that polyploid cases are relatively rare. We also establish a temporal order by which the different imbalances occur and show that at least two cytogenetic pathways exist, one dominated by gains and another by losses. We also show that these pathways are well separated and do not share a common set of late imbalances.

Biological Evolution↗

PubMed2004

Statistical dissection of cytogenetic patterns in lung cancer reveals multiple modes of karyotypic evolution independent of histological classification.

Lung carcinomas are cytogenetically highly complex. In spite of this, patterns of recurrent chromosome aberrations have emerged. Apart from the frequent loss of 3p, losses of 4q, 5q, 8p, 9p, 10q, 13q, and 17p are common and gains often include 1q, 3q, 5p, and 8q. In the present study, we retrieved all aberrant lung carcinoma karyotypes, in total 432 cases, from the Mitelman Database of Chromosome Aberrations in Cancer and identified the most frequent imbalances. Each case was then classified with respect to the presence or absence of these imbalances and the data were statistically analyzed by means of principal component analysis, multidimensional scaling, and hierarchical cluster analysis. The analyses suggest that lung cancer develops through three pathways, initiated by +7, 3p-, and +12, respectively, and that the 3p- pathway is dominated by losses and the +12 pathway by gains. Gain of chromosome 7 was shown to be both important in the 3p- pathway and also forming a group of tumors containing +7 and +20 (with few additional changes). The distribution of the number of imbalances per tumor indicated that the karyotypic evolution might pass through three different phases. Phase I is characterized by tumors with few changes and by well-separated 3p- and +12 pathways. Phase II cases have an increased number of imbalances and exhibit less distinct 3p- and +12 pathways. Phase III tumors are polyploid and highly complex. No marked differences between the karyotypic profiles were found among morphologic subtypes, suggesting that lung cancer morphology is independent of the particular cytogenetic pathway operating in the tumor cells.

Adenocarcinoma↗

PubMed2004

Cytogenetic analysis of three variants of clival chordoma.

Chordoma is an uncommon malignant neoplasm derived from remnants of the embryonal notochord. The tumor arises in the sacrococcygeal region in most cases. Cytogenetic information on clival chordomas is scarce due to the low incidence of these tumors. In this study, we applied the G-banding and spectral karyotyping techniques to compare the karyotypes of three variants of clival chordoma: conventional, chondroid, and dedifferentiated. We describe a normal karyotype of a chondroid chordoma and a complex karyotype of a conventional chordoma involving chromosomes 1, 2, 3, 5, 8, 9, 11, 15, 19, 20, and X. The cytogenetic analysis of the dedifferentiated chordoma showed a polyploid complex karyotype of 71-123 chromosomes with double minutes that originated from chromosome 17.

Aged↗

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