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At least 1,315 records · Page 73Linked to original sources
PubMed1975

Relationship between deoxyribonucleic acid content and nucleoli in human heart muscle cells and estimation of cell number during cardiac growth and hyperfunction.

In the myocardium of 30 human hearts of all age groups quantitative deoxyribonucleic acid (DNA) measurements were performed and the results of the measurements were correlated with the pure myocardium weight. By means of the diphenylamine reaction the total amount of DNA (DNA concentration and DNA amount) in the myocardium was estimated. By means of Feulgen cytophotometry the DNA amount exclusively in the heart muscle cell nuclei was measured. With the use of myocardial tissue spread on slides, the nuclear areas of the heart muscle nuclei were planimetrically measured. After preparation with DNase and staining with gallocyanine chromalumn the nucleoli in heart muscle nuclei were specifically presented and their number per nucleus as well as their area values were demonstrated. From the biochemical and cytophotometric results of the myocardial DNA content it was possible to estimate the absolute cell number of the hearts, keeping the pure myocardium weight in consideration. The investigations led to the following results. In growing childrens' hearts the DNA concentration decreases to a constant level of 0.3-0.4 mg/g. The amount of DNA rises with increasing heart weight. During the growth of the heart of a child between the ages of 8 and 12 the DNA amount doubles in the heart muscle nuclei, and most of the muscle nuclei of an adult have a tetraploid DNA content. In pathological heart hypertrophy a further polyploidization of the heart muscle nuclei occurs. The areas of the nuclei increases with growing polyploidization. The nuclear areas form the same grouping as the ploidy classes. With growing nuclear areas, the total areas of the nucleoli and their number per nucleus also increase. Right after birth an increase in the number of connective tissue and heart muscle cells follows. A normal heart contains about 2 x 10(9) muscle cells. In hypertrophic hearts the number of muscle cells can double.

Aged↗
PubMed1992

[Polyploidy and polyteny in the trophoblast cells of the mink].

According to cytophotometry, trophoblast cells in the mink placenta are both diploid and polyploid, the ploidy level ranging from 2c to 64c. A great number of mink trophoblast cells were seen to divide mitotically. In addition to the ordinary mitotic figures, polyploid mitoses as well as abnormal mitotic figures were observed. Non-classic polytene chromosomes, peculiar to the mammalian trophoblast, appeared in the mink trophoblast cells to have the highest ploidy. A relatively low ploidy degree is due, probably, to a lesser invasive activity of the mink trophoblast cells as compared to the rodent giant trophoblast cells.

Animals↗
PubMedDate not supplied

[Prognostic value of the chromosome pattern in tumors of the urinary bladder].

Cytodiagnostic and histopathological studies were made in 42 cases of epithelial urinary bladder tumours. The correlation was investigated between the modal chromosomal number, the frequency of the structural chromosomal aberrations and the degree of histologic malignancy (cellular anaplasy and invasion of the bladder wall). The proliferative rate was also determined of the analized tumours. In all the epithelial tumours that have been studied it was noted that the more malignant the tumour, the higher was the value of the modal chromosomal number, and the more frequent the chromosomal abnormalities. The proliferative rate of polyploid tumours was significantly higher as compared with that of the diploid ones. The presence of a polyploid mitotic population, as well as of structural chromosomal disturbances in a tumour with a low degree of malignancy, as demonstrated histologically, may have a prognostic significance.

Carcinoma↗
PubMedDate not supplied

[Cytogenetic changes in the Namalwa cell line of human malignant lymphoma induced by inhibitors of DNA replication and synthesis].

Namalwa cells originating from the malignant human lymphoma have been analyzed cytogenetically upon short-time exposure to subtoxic doses of inhibitors of DNA replication and synthesis, either etoposide or fludarabine. The intact cells were characterized by the modal class of the chromosomes within the diploid range with the proportion of the aberrant cells amounting to 16.0 +/- 0.5%. Upon exposure to etoposide the percentage of the aberrant cells increased amounting to 26.1 +/- 2.9 through 39.8 +/- 1.7% depending on the duration of the exposure and the dose of the drug. At the same time the number of the polyploid cells increased but the modal class retained within the diploid range. Upon exposure to fludarabine the percentage of the cells with the aberrant chromosomes increased to 57.1 +/- 2.9%. Two modal classes appeared--the first approaching the diploid number and the second being polyploid. The exposure to either etoposide or fludarabine resulted in increasing number of the chromatide aberrations with more frequent involvement of #1, #2, #5, #6, #7, #11, #13, #14, #16 and #17 chromosomes. The data obtained have shown the susceptibility of Namalwa cells to the subtoxic concentrations of the inhibitors of DNA synthesis and replication used in the study resulting in the survival of the novel clones resistant to the drugs.

Cell Line, Tumor↗
PubMed2004

Defective control of mitotic and post-mitotic checkpoints in poly(ADP-ribose) polymerase-1(-/-) fibroblasts after mitotic spindle disruption.

Poly(ADP-ribose) polymerase-1 (PARP), a DNA damage-responsive nuclear enzyme present in higher eukaryotes, is well-known for its roles in protecting the genome after DNA damage. However, even without exogenous DNA damage, PARP may play a role in stabilizing the genome because cells or mice deficient in PARP exhibit various signs of genomic instability, such as tetraploidy, aneuploidy, chromosomal abnormalities and susceptibility to spontaneous carcinogenesis. Normally, cell cycle checkpoints ensure elimination of cells with genomic abnormalities. Therefore, we examined efficiency of mitotic and post-mitotic checkpoints in PARP-/- and PARP+/+ mouse embryonic fibroblasts treated with mitotic spindle disrupting agent colcemid. PARP+/+ cells, like most mammalian cells, eventually escaped from spindle disruption-induced mitotic checkpoint arrest by 60 h. In contrast, PARP-/- cells rapidly escaped from mitotic arrest within 24 h by downregulation of cyclin B1/CDK-1 kinase activity. After escaping from mitotic arrest; both the PARP genotypes arrive in G1 tetraploid state, where they face post-mitotic checkpoints which either induce apoptosis or prevent DNA endoreduplication. While all the G1 tetraploid PARP+/+ cells were eliminated by apoptosis, the majority of the G1 tetraploid PARP-/- cells became polyploid by resisting apoptosis and carrying out DNA endoreduplication. Introduction of PARP in PARP-/- fibroblasts partially increased the stringency of mitotic checkpoint arrest and fully restored susceptibility to G1 tetraploidy checkpoint-induced apoptosis; and thus prevented formation of polyploid cells. Our results suggest that PARP may serve as a guardian angel of the genome even without exogenous DNA damage through its role in mitotic and post-mitotic G1 tetraploidy checkpoints.

Animals↗
PubMed2004

[Genetic control of mitosis. Mast(v40) protein--an element of checkpoints system?].

The effect of the mastv40 mutation was studied using neural ganglion cells of third-instar larvae of Drosophila melanogaster. The distributions of the cells by the interphase nucleus diameter and by the distance between the sister chromosome sets in anaphase were analyzed. Three following types of defects induced by the mutation were described: (1) Monopolar mitosis or, in the case of bipolar mitosis, an abnormally short distance between the sister chromosome sets in anaphase and early telophase. We believe that these abnormalities are caused by damage of the start and (or) motor mechanisms of centrosome separation at the beginning and in the end of mitosis. (2) Lagging and bridging of chromosomes in anaphase and early telophase. These defects seem to be related to the disruption of functioning of mitotic spindle microtubules and (or) their defective attachment to the appropriate kinetochores. (3) Unlimited division of aneuploid and polyploid cells, which may be explained either by inactivation of the checkpoint system controlling the genome ploidy or by checkpoint adaptation. Taken collectively, our results and literature data suggest that the MAST protein is an element of the checkpoint system and that division of aneuploid and polyploid cells results from inactivation of the checkpoints.

Aneuploidy↗
PubMed2004

[Cell response of rat liver parenchyma to the infection by the intestinal protozoan pathogen Cryptosporidium parvum (Sporozoa, Coccidia)].

In the present work, the authors' previous studies of a "distant action", exerted by an intestinal pathogen (Cryptosporidium parvum) on the liver of experimentally infected baby rats, were extended to include shifts in the quantity of glycogen, protein and nuclear DNA in the host liver at different degrees of infection. One of the outcomes of this work is the discovery of a very quick response of hepatocytes and a high sensitivity of rat liver to parasitic invasion even at a weak intensity of infection. 85-90 h after oocyst feeding to rats, glycogen quantity in their livers was 2.5 times lower that in the control. This suggests that the infected host liver worked under energetic starvation conditions. The proposed coefficients of general infection (I) and infection with intracellular stages (F) made it possible to distinguish between the total abundance of parasites in the host intestine during the whole period of infection, and the number of feeding intracellular stages available by the moment of autopsy. The glycogen amount in rat hepatocytes does not depend on I, and negatively correlates with F. Unlike, the protein content in hepatocytes positively correlates with I, being independent of F. Despite the obvious deficiency of amino acids in the infected rats, as a consequence of cryptosporidiosis-induced malabsorption, the protein synthesis in their hepatocytes was not at all inhibited but, on the contrary, much activated. This is a most characteristic feature of the distant action of C. parvum on the liver of parasitized host. With C. parvum infection, the share of polyploid hepatocytes does not correlate with either I, or F. However, compared to the control, the mean values of relative numbers of polyploid cells in weakly, moderately, and heavily infected animals (according to I values) were higher by 20, 100 and 100%, respectively. In hepatocyte nuclei of C. parvum infected rats, the total area of nucleoli increases almost by 30%. The above changes are discussed in terms of both the liver compensatory response to the existing pathology (diarrhea), and the host-parasite relationships. Studies into the distant action of an intestinal pathogen (C. parvum) on non-intestinal organs (liver) of the infected host may be qualified as a new and original approach to pathogenesis of protozoan infections (coccidioses sensu lato), to which young host specimens are known to be most susceptible.

Animals↗
PubMed2003

A numerical taxonomic study of several Cobitis species (Pisces, Cobitidae) based on their cytogenetic features.

Some of the cytogenetical features (known also as chromosomal sets in karyotypes of polyploid forms) of Cobitis species in Poland and in other populations from Russia, the Czech Republic and England were compared using a numerical taxonomy method in order to reveal the relationships between them. The results obtained confirmed that in addition to C. taenia and C. elongatoides, C. tanaitica took part in the origin of polyploids from Poland. The numerical taxonomy method, revealing the relationships between the Cobitis fish species, provided evidence for assigning them into two groups: one containing C. taenia, C. tanaitica and C. melanoleuca with karyotypes dominated by uniarmed chromosomes and the second consisting of C. elongatoides and C. vardarensis with karyotypes dominated by biarmed chromosomes.

Animals↗
PubMed2003

Genetics of the loach, Misgurnus anguillicaudatus: recent progress and perspective.

The loach Misgurnus anguillicaudatus is an interesting fish from the viewpoint of polyploidy and its related atypical reproduction. Among Japanese populations, bisexual diploid individuals are most common, but natural triploids have been recorded in some localities. Experimental crosses including induced gynogenesis and inter-specific hybridization showed that triploid loaches arose from unreduced eggs formed by sympatric diploids. Two types of unreduced eggs produced by these diploid females, bisexual and unisexual reproduction, have been identified by molecular genetic analysis. The first one required fertilization with normal sperm and produced triploids. The other one normally initiated spontaneous gynogenesis as clone, but sometimes incorporated sperm genome to generate triploid progeny. Natural tetraploids found in the specimens from commercial sources were considered as exotic fish. Progenies of tetraploid loaches such as triploids, pentaploids, and other polyploids exhibited various atypical modes of reproduction. Allozyme genetics suggested possible involvement of two or more cryptic species or races on natural polyploidization through their hybridizations and further studies using more sensitive markers are required. Recent progress in molecular techniques makes it possible to map DNA markers on the loach chromosomes. Such approaches will identify genomic synteny among cobitids. Integration of chromosome manipulation, transgenics, germ-line chimera and nuclear transplantation will open new possibilities of loach as a new experimental model, not only for basic biology, but also for aquaculture biotechnology.

Animals↗
PubMed1992

[Ploidies of cardiomyocytes in human myocardial hypertrophy].

DNA cytophotometry has been performed in ventricular cardiomyocytes of hypertrophic human hearts. In the cases of hypertrophy in adults (generalized atherosclerosis, postinfarct scars), polyploidy expression did not exceed the limits of normal variability developed during childhood. In the cases of hypertrophy caused by congenital heart defects, high polyploidy has been revealed (the mean level 20c and more, where c is haploid DNA content), which considerably exceeded the upper limit of normal variability (approximately 10c). Our hypothesis has confirmed that heart hypertrophy in adults proceeds in conditions of stable genome rather than due to redundant polyploidization of the ventricular myocytes. The same idea assumes enhanced polyploidization of the myocytes in childhood in humans with congenital heart diseases.

Adult↗
PubMedDate not supplied

[Genetic variability among Solanum and Lycopersicon species revealed by amplified fragment restriction polymorphism analysis of chloroplast DNA].

A phylogenetic cladogram for 23 species of genera Solanum and Lycopersicon was constructed based on restriction analysis of 10 amplified regions of chloroplast DNA. Three major clusters were detected. All Lycopersicon species and S. lycopersicoides formed the first group. Second cluster was occupied by S. verrucosum, polyploid species of series Longipedicellata, and all dyploid and polyploid species native to South America. Two diploid series Pinnatisecta and Bulbocastana were grouped together in the last claster. Previous morphological and molecular markers strongly support this type of phylogenetic analysis. Based on presented results it is evident that combination of chloroplast DNA region amplification and restriction could be a valuable alternative to a standard-RFLP analysis.

Cluster Analysis↗
PubMedDate not supplied

[Increase of mitochondrial DNA copies with low level of DNA repair in tissue cells of gamma-irradiated mice].

The damage and the change in the number of mitochondrial DNA (mtDNA) copies in brain and spleen tissues of gamma-irradiated mice were studied. The changes in the number of mitochondrial DNA (mtDNA) copies were assayed by the comparative analysis of the density values of long-extension PCR products of the mtDNA fragments (16 kb) and the cluster nuclear gene of beta-globin (8.7 kb). PCRs of mtDNA fragments and the nuclear gene of beta-globin were carried out simultaneously in one test-tube within total DNA. Our results showed that in brain and in spleen cells of mice exposed to gamma-radiation an increase in copy number (polyploidization) of mtDNA with regard to the nuclear gene beta-globin took place. The induction of polyploidization of mtDNA observed in cells of gamma-irradiated animals is regarded as the development of a compensatory reaction because of the energy deficiency due to the increased ATP consumption and structural alteration of genes controlling OXPHOS. The data enabled the assumption that because of the low efficiency of repair systems in mitochondria the induction of synthesis of new mtDNA copies on intact or little affected mtDNA templates may be the major mechanism for the retention of the mitochondrial genome which is constantly damaged by the endogenous ROS and is affected by ionizing radiation and/or other exogenous factors.

Animals↗
PubMed2005

[The standardization of genetic terms--I. Of the same name with different definition phenomenon].

The phenomenon of same term with different definitions exists widely in genetic teaching courses. The present paper was aiming at analyzing and discussing these problems. For example, the terms such as Y-linked inheritance, sex-limited inheritance, sex-influenced inheritance, haploid, polyploid and cumulative effect expression are very confused and chaotic in meaning, even mutually contradictory. This involves the accuracy of nomenclature. We presumed that the term of Y-linked inheritance cannot confuse with that of sex-limited inheritance, and that though the sex-limited factor and the sex-influenced inheritance gene are both located on autosome with some distance, but they are still different. Haploid refers to the gametophyte chromosome number an individual has, but does not equate to monoploid. Also we thought that polyploid represented the basic number of chromosome, such as triploid indicated for 3x. And, the cumulative effect refers to mutual accumulation function between the exponential quantitative characters of relevant genes.

Genes, Y-Linked↗
PubMed2005

The effect of self-fertilization, inbreeding depression, and population size on autopolyploid establishment.

The minority cytotype exclusion principle describes how random mating between diploid and autotetraploid cytotypes hinders establishment of the rare cytotype. We present deterministic and stochastic models to ascertain how selfing, inbreeding depression, unreduced gamete production, and finite population size affect minority cytotype exclusion and the establishment of autotetraploids. Results demonstrate that higher selfing rates and lower inbreeding depression in autotetraploids facilitate establishment of autotetraploid populations. Stochastic effects due to finite population size increase the probability of polyploid establishment and decrease the mean time to tetraploid fixation. Our results extend the minority cytotype exclusion principle to include important features of plant reproduction and demonstrate that variation in mating system parameters significantly influences the conditions necessary for polyploid establishment.

Computer Simulation↗
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↗
PubMed2006

Influence of experimental hyperthyreosis on hepatocytes' cell cycle in white mice.

The thyroid hormones play the essential regulatory role in the process of hepatocyte proliferation and polyploidization. T3 has been shown to be a powerful inducer of hepatocyte proliferation in the rats. Although T3 is known to have a strong mitogenic effect on hepatocytes in vivo, little is known about long-term effects of thyroid hormone on liver parenchyma. Here we have studied the effect of thyroid hormone on the cell cycle of hepatocytes in white mice during experimental hyperthyreosis. The experiments were performed on 74 white mice, distributed in three age groups (juveniles, adults, senescents). Experimental hyperthyreosis was induced by injections of L-thyroxine (50 mcg/1 kg body weight). The method of flow cytometry was used. The results obtained allowed us to clarify the predominant role of thyroid hormones in the regulation of hepatocyte cell cycle. The significant role of the hyperthyroid status on liver polyploidization was evident. However, this effect seems to be age dependent. According to our data, hyperthyreosis in juveniles increases the degree of ploidity, whereas in adult and senescent mice--decreases. On the other hand, under action of hyperthyroid status the amount of apoptotic nuclei decreases in juveniles and increases in adults and senescents.

Animals↗
PubMed1990

[The reparative potentials of human corneal endothelium from the aspect of age].

Morphometric and cytospectrophotometric studies of the endothelium of human cornea in age aspect, from 20 to 80 years, has revealed the presence of nuclei with double content of DNA (4 c) irrespective of age, as well as binuclear cells. Their number increases with age. At the age of 20-40 years, 4 tetraploid nuclei and 3 binuclear cells were found, and after 80 years of age - 45 tetraploid nuclei and 11 binuclear cells per a cornea. This speaks about the ability of the endothelium cell of the human cornea to incomplete polyploidizing cellular mitosis-variant of a normal proliferation of the cells and is characteristic for long-living and slightly proliferating tissues. The increase of the number of polyploid cells in the corneal endothelium with age speaks about activation of adaptation mechanisms in the course of age involution.

Adult↗
PubMed2006

Microsporogenesis in Brachiaria dictyoneura (Fig. & De Not.) Stapf (Poaceae: Paniceae).

Microsporogenesis was analyzed in five accessions of Brachiaria dictyoneura presenting x = 6 as the basic chromosome number. All accessions were tetraploid (2n = 4x = 24) with chromosome pairing in bi-, tri-, and quadrivalents. The recorded meiotic abnormalities were those typical of polyploids, including precocious chromosome migration to the poles, laggard chromosomes, and micronucleus formation. The frequency of these abnormalities, however, was lower than those reported for other polyploid accessions previously analyzed for other Brachiaria species. Cell fusion and absence of cytokinesis were also recorded in some accessions, leading to restitutional nucleus formation in some cells. Genetically unbalanced microspores, binucleate, and 2n microspores were found among normal meiotic products as results from these abnormalities. The limitation in using these accessions as pollen donor in interspecific crosses with sexual species with x = 7 or x = 9 in breeding programs is discussed.

Brachiaria↗