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PubMedDate not supplied

Image analysis of Feulgen-stained c-H-ras-transformed NIH/3T3 cells.

Feulgen-DNA content, nuclear phenotypes, and levels of chromatin condensation were evaluated by image analysis in NIH/3T3 cells transformed with the c-H-ras oncogene of T24 cells. Three nuclear phenotypes, differing from those of untransformed control cells and defined in terms of patterns of chromatin condensation, were demonstrated microspectrophotometrically for the tumor cells. Polyploidy could only be observed in nuclei with extensive and deeply stained areas covered with condensed chromatin, i.e., only in a small fraction of the tumor cell nuclear population. The increased chromatin condensation that appeared with cell transformation affected the euchromatin zones. The image analysis provided data that, compared with those obtained in other situations involving cell transformation, could be relevant to the understanding of changes in chromatin supraorganization related to tumorigenesis and to tumor cell diagnosis.

Animals↗
PubMed1992

Influence of chronic nadolol treatment on blood pressure and vascular changes in spontaneously hypertensive rats.

Chronic treatment of spontaneously hypertensive rats (SHR) and Kyoto-Wistar normotensive rats (WKY) with nadolol was carried out from gestation until 28 weeks of age. Nadolol treatment caused some lowering of blood pressure but did not prevent the development of hypertension or cardiac hypertrophy in the SHR, in spite of significant beta-blockade. The lumen of large mesenteric arteries from control SHR was smaller than from WKY, and nadolol treatment increased the lumen size in the SHR. An increased number of smooth muscle cell layers present in the control SHR as compared with WKY was reduced slightly by nadolol treatment. However, the changes produced by nadolol did not reach the levels of control and treated WKY. In the aorta, the incidence of polyploid smooth muscle cells was higher in the SHR than the WKY in the control group. Nadolol treatment reduced the percentage of polyploid cells in both SHR and WKY, so that the difference between these two groups of animals was eliminated in the treated groups. The tissue level of norepinephrine in the plasma, heart, mesenteric arteries, and adrenal glands in the SHR and WKY was not affected by the treatment. We suggest that the ineffectiveness of nadolol in preventing hypertension development may be due to its lack of effect in preventing primary changes in the resistance arteries, and that the development of polyploidy of smooth muscle cells may be mediated by beta-receptors.

Adrenal Glands↗
PubMed2006

Cell cycle regulation in plant development.

Cell cycle regulation is of pivotal importance for plant growth and development. Although plant cell division shares basic mechanisms with all eukaryotes, plants have evolved novel molecules orchestrating the cell cycle. Some regulatory proteins, such as cyclins and inhibitors of cyclin-dependent kinases, are particularly numerous in plants, possibly reflecting the remarkable ability of plants to modulate their postembryonic development. Many plant cells also can continue DNA replication in the absence of mitosis, a process known as endoreduplication, causing polyploidy. Here, we review the molecular mechanisms that regulate cell division and endoreduplication and we discuss our understanding, albeit very limited, on how the cell cycle is integrated with plant development.

Arabidopsis Proteins↗
PubMed2005

Coupled expression of troponin T and troponin I isoforms in single skeletal muscle fibers correlates with contractility.

Striated muscle contraction is powered by actin-activated myosin ATPase. This process is regulated by Ca(2+) via the troponin complex. Slow- and fast-twitch fibers of vertebrate skeletal muscle express type I and type II myosin, respectively, and these myosin isoenzymes confer different ATPase activities, contractile velocities, and force. Skeletal muscle troponin has also diverged into fast and slow isoforms, but their functional significance is not fully understood. To investigate the expression of troponin isoforms in mammalian skeletal muscle and their functional relationship to that of the myosin isoforms, we concomitantly studied myosin, troponin T (TnT), and troponin I (TnI) isoform contents and isometric contractile properties in single fibers of rat skeletal muscle. We characterized a large number of Triton X-100-skinned single fibers from soleus, diaphragm, gastrocnemius, and extensor digitorum longus muscles and selected fibers with combinations of a single myosin isoform and a single class (slow or fast) of the TnT and TnI isoforms to investigate their role in determining contractility. Types IIa, IIx, and IIb myosin fibers produced higher isometric force than that of type I fibers. Despite the polyploidy of adult skeletal muscle fibers, the expression of fast or slow isoforms of TnT and TnI is tightly coupled. Fibers containing slow troponin had higher Ca(2+) sensitivity than that of the fast troponin fibers, whereas fibers containing fast troponin showed a higher cooperativity of Ca(2+) activation than that of the slow troponin fibers. These results demonstrate distinct but coordinated regulation of troponin and myosin isoform expression in skeletal muscle and their contribution to the contractile properties of muscle.

Actin Cytoskeleton↗
PubMed1989

Control of hypertrophic versus hyperplastic growth of vascular smooth muscle cells.

A long-term objective of my laboratory has been to understand the mechanisms that regulate both normal and developmental growth of vascular smooth muscle as well as the accelerated growth of smooth muscle that occurs in atherosclerotic lesions or arteries of hypertensive patients and animals. Previous studies in this and other laboratories have demonstrated that smooth muscle cells are capable of two distinct growth responses in vivo, depending on the nature of the growth stimulus. Smooth muscle cell growth in large vessels of chronically hypertensive animals appears to occur primarily by enlargement of preexisting cells (i.e., cellular hypertrophy) with little or no cell proliferation (hyperplasia) and is accompanied by development of polyploidy in a large fraction of the cells. In contrast, in experimental injury models of atherogenesis, or after induction of severe acute hypertension, aortic smooth muscle cells undergo a classic proliferative response. This lecture focuses on possible control mechanisms for hypertrophy of vascular smooth muscle, with particular emphasis on examination of the possible role of contractile agonists as hypertrophic agents, exploration of how this process differs from cellular hyperplasia, discussion of the possible mechanisms for formation of polyploid cells, and examination of the role of mechanical factors in growth regulation of vascular smooth muscle cells.

Animals↗
PubMed1993

Urea selectively induces DNA synthesis in renal epithelial cells.

Hyperosmotic stress with the functionally impermeant solute NaCl has been shown by us and others to inhibit cell growth and DNA synthesis. Several lines of evidence suggest that urea, the other principal renal medullary solute, may exert a growth-promoting effect on renal epithelial cells. Among these is the finding that urea upregulates expression at the mRNA level of two growth-associated immediate-early genes, Egr-1 and c-fos. In the present study, urea, in concentrations characteristic of the renal medulla, increased [3H]thymidine incorporation approximately threefold in confluent, growth-suppressed Madin-Darby canine kidney (MDCK) cells, whereas another readily membrane-permeant solute, glycerol, did not. Urea also overcame the inhibitory effect of hyperosmotic NaCl on DNA synthesis. The urea-induced increase in [3H]thymidine incorporation was also evident in the renal epithelial LLC-PK1 cell line, but not in renal nonepithelial and epithelial nonrenal cell types examined. In addition, it was associated with a 15% increase in total DNA content measured fluorometrically at 24 h of treatment. There was, however, no associated increase in cell proliferation as measured by cell number, total protein content, or cell cycle distribution. Urea also failed to induce polyploidy or aneuploidy. Therefore cells of renal epithelial origin may be uniquely capable of responding to hyperosmotic urea with increased DNA synthesis through an undefined and potentially novel mechanism.

Animals↗
PubMed1994

Growth and characterization of porcine urinary bladder epithelial cells in vitro.

Dividing long-term monolayer cultures of porcine urinary bladder epithelial cells were obtained by a combined mechanical and enzymatic isolation method. The serum-free cultured cells were investigated morphologically and characterized according to their growth characteristics and enzymatic functions. Investigations over a period up to 12 wk demonstrated that the cells regain their in vivo polarization with apically situated membrane vesicles and tight junctions between neighboring cells when they have built up a confluent monolayer. Activities of most marker enzymes for cell-differentiated status and function of such cells observed over a period of 4 wk in culture were conserved compared with the original tissue. Lactate dehydrogenase activity release into the medium was at low levels (< or = 5% of the total amount), indicating a good membrane integrity and cell viability. The chromosome set (2n = 38) did not change significantly during the first 5 wk, but, with additional culture time, the degree of polyploid and polynucleated cells increased comparable to the in vivo situation, in which the apical cell layer of the bladder mucosa also showed a high degree of polynucleation and polyploidy, indicative of a senescence process.

Animals↗
PubMed2005

CDC4 mutations occur in a subset of colorectal cancers but are not predicted to cause loss of function and are not associated with chromosomal instability.

CDC4/FBXW7 is part of a ubiquitin ligase complex which targets molecules such as cyclin E, c-myc, and c-jun for destruction. CDC4 mutations occur in several cancer types and are best described in colorectal tumors. Knockout of CDC4 in vitro in colorectal cancer cells causes changes suggestive of chromosomal instability (CIN). In p53(+/-) mice, radiation-induced lymphomas show deletion or mutation of one copy of CDC4 and knockdown of CDC4 leads to increased aneuploidy in mouse fibroblasts. We screened 244 colorectal tumors and 40 cell lines for CDC4 mutations and allelic loss. Six percent (18 of 284) of tumors, including near-diploid (CIN-) lesions, harbored CDC4 mutations and there was no association between mutation and CIN (polyploidy). The CDC4 mutation spectrum in colorectal tumors was heavily biased towards C:G > T:A changes, either missense mutations at critical arginine residues or nonsense changes in the 5' half of the gene. The reasons for this odd mutation spectrum were unclear but C:G > T:A changes were not found more often than expected at APC, K-ras, or p53 in the same tumors and we found no specific defects in DNA repair to account for the observations. No colorectal tumor was found to carry two CDC4 mutations predicted to abolish protein function; partial loss of CDC4 function may therefore cause tumorigenesis. The in vitro studies, therefore, did not assess the functional effects of mutant alleles which are found in vivo. CDC4 mutations may be selected primarily to drive progression through the cell cycle although CIN might be an important secondary effect in some cancers.

Adenocarcinoma↗
PubMedDate not supplied

Chromosomal anomalies in abnormal human pregnancies.

OBJECTIVE: The aim of this study was to describe the cytogenetic observations on abnormal human pregnancies (anembryonic pregnancy, early fetal loss, and hydatidiform moles), and to detect the most frequent or typical chromosomal aberration for anembryonic pregnancy and early fetal loss. STUDY DESIGN: Abnormal pregnancies were divided into three clinical and morphological groups: (a) anembryonic pregnancy; (b) early fetal loss, and (c) hydatidiform mole. Of the 119 karyotyped tissue samples, 42 (35%) were from anembryonic pregnancies, 64 (54%) from early fetal losses, and 13 (11%) were from hydatidiform moles (6 complete and 7 partial moles). Long-term cultures of chorionic villi and GTG-banding techniques were used for chromosome analysis. RESULTS AND CONCLUSION: The overall frequency of chromosome anomalies among the 119 karyotyped spontaneous abortions was found to be 37.8%. Trisomy (double trisomy included) accounted for 35.6% of all aberrations, followed by polyploidy (33.3%), mosaicism (11.1%), structural abnormalities (4.4%), and monosomy X (2.2%). Although the difference was not statistically significant, single trisomy was the predominant chromosome abnormality found in anembryonic pregnancies (64.3 %) while in cases of early fetal loss, trisomy (double trisomy included) (38.9%) and triploidy (27.8%) were quite frequently present. The frequency of triploidy among all chromosomal abnormalities was 28.9%, and 53.8% of them were found in partial hydatidiform mole. The rest of them were almost exclusively found in early fetal losses. Complete hydatidiform moles (androgenetic in origin) were present in 13.3% of all aberrations, of which 83.3% had a 46,XX, and the rest of them had a 46,XY karyotype.

Abortion, Missed↗
PubMed1999

PCR protocol to detect parental origin and hidden mosaicism inSex chromosome aneuploidies.

In this study, we report an accurate method to determine the parental origin of sex chromosome aneuploidies or polyploidies and to detect low percentage mosaicisms. We have amplified by polymerase chain reaction (PCR) five polymorphic markers along the X chromosome (DXS1283E, DYS II, DMD49, AR and DXS52) and three markers along the Y chromosome (SRY, DYZ3 and DYZ1). False-negative results were discarded by the simultaneous amplification of Y markers and of internal controls. We have applied this protocol to a series of 14 Turner syndrome patients with a 45,X karyotype. We have detected sex chromosome mosaicisms in two patients. The parental origin of the syndrome has been determined in the other 12 patients.

Female↗
PubMed2003

Mixed chimerism of erythro- and megakaryopoiesis following allogeneic bone marrow transplantation.

Until now, studies on mixed chimerism (MCh) after allogeneic bone marrow transplantation (BMT) have predominantly focused on the B- and T-lymphocyte population, but not on distinct myeloid cell lineages like nucleated erythroid precursors and megakaryocytes. To evaluate the lineage-restricted MCh more explicitly in 10 patients with chronic myelogenous leukemia (CML), a quantitative analysis was performed on bone marrow biopsies following a sex-mismatched host/donor constellation. Techniques included immunophenotyping (antiglycophorin C, CD61) for the identification of erythro- and megakaryopoiesis and a simultaneously conducted genotyping with x- and y-chromosome-specific DNA probes. Normal bone marrow and specimens taken before BMT served as controls. Contrasting a total gender-dependent sex-typing in the latter samples in the early and late posttransplant period (up to 586 days), 3-9% erythroid precursors and about 16% megakaryocytes revealed a host-type origin. This significantly higher number of host megakaryocytes is explained by their polyploidy generating an increased probability to detect positive signals at a certain section level of the corresponding biopsies. A striking conversion of MCh to a recipient cell type was found in leukemic relapse with a more than 90% host-derived erythroid and megakaryocytic cell population in 4 patients approximately 643 days after BMT.

Adult↗
PubMed2005

LTR retrotransposons and flowering plant genome size: emergence of the increase/decrease model.

Long Terminal Repeat (LTR) retrotransposons are ubiquitous components of plant genomes. Because of their copy-and-paste mode of transposition, these elements tend to increase their copy number while they are active. In addition, it is now well established that the differences in genome size observed in the plant kingdom are accompanied by variations in LTR retrotransposon content, suggesting that LTR retrotransposons might be important players in the evolution of plant genome size, along with polyploidy. The recent availability of large genomic sequences for many crop species has made it possible to examine in detail how LTR retrotransposons actually drive genomic changes in plants. In the present paper, we provide a review of the recent publications that have contributed to the knowledge of plant LTR retrotransposons, as structural components of the genomes, as well as from an evolutionary genomic perspective. These studies have shown that plant genomes undergo genome size increases through bursts of retrotransposition, while there is a counteracting process that tends to eliminate the transposed copies from the genomes. This process involves recombination mechanisms that occur either between the LTRs of the elements, leading to the formation of solo-LTRs, or between direct repeats anywhere in the sequence of the element, leading to internal deletions. All these studies have led to the emergence of a new model for plant genome evolution that takes into account both genome size increases (through retrotransposition) and decreases (through solo-LTR and deletion formation). In the conclusion, we discuss this new model and present the future prospects in the study of plant genome evolution in relation to the activity of transposable elements.

Flowers↗
PubMed2006

Historical development of analysing large-scale changes in the human genome.

A widely held belief today is that genomics really only started with the DNA sequence information emanating from the genome programs for various organisms, with the human genome playing the leading role. In fact there is a discernable trail stretching for more than a 100 years from the observations of Boveri on tissue instability involving polyploidy in sea urchin embryos and human tumours to the present day. This historical review follows that trail and shows that many theoretical and technical advantages taken for granted in today's genomics era rely heavily on earlier cytogenetic and gene mapping discoveries. Three specific examples of technical developmental paths involving in situ hybridisation, flow-sorting and DNA reassociation kinetics will be explored. In the mid-1980s the two former approaches merged to give rise to several applications of which chromosome painting and chromosome CGH are arguably the most important. The latter developed into array CGH which has now become the pre-eminent method for detecting micro-imbalances in a large number of targets. A competing emerging technology is that of genome-wide SNP typing, which itself is a product of the much earlier RFLP approach linked to DNA sequence information. Do such approaches spell the final demise of the microscope? Perhaps for narrowly defined activities this may occur, but for addressing general questions, microscopic examination will remain pre-eminent.

Genetic Techniques↗
PubMed1992

Sperm age, sex ratio, and hyperhaploidy frequency in mice.

Physiologically aged and unaged sperm from each of 12 sexually mature B6SJLF1/J mice were used to fertilize oocytes from females of the same strain, with each male serving as its own control. Male genomes in 323 and 307 first-cleavage metaphases obtained by in vivo and in vitro fertilization, respectively, were analyzed cytogenetically, using C-banding for detection of the Y chromosome. The sex (X:Y) ratio among all zygotes resulting from in vivo fertilization was 1.18; in zygotes resulting from in vivo fertilization by aged (14-d mating intervals) sperm, however, the ratio was 1.53, which differed significantly (chi 2 = 6.72, P less than 0.01) from the theoretical value of 1.00. Comparison of the sex ratio in zygotes resulting from in vivo fertilization by unaged sperm (3-d mating intervals), 0.94, with that in zygotes resulting from fertilization by aged sperm (using a 2 x 2 contingency table) showed a significant (chi c2 = 4.19, P less than 0.05) relationship between sex ratio and sperm age. In vitro neither the combined nor the individual 3- and 14-d data deviated significantly from the expected sex ratio of 1.00. The frequency of sperm-derived hyperhaploidy did not differ significantly between the in vivo (3.4%) and in vitro (5.9%) populations, but did between unaged (2.5%) and aged (6.8%) sperm (chi c2 = 5.74, P less than 0.01). All hyperhaploid zygotes had a complement of n + 1 chromosomes, except the 14-d in vitro group, where complements of n + 2 and n + 3 chromosomes were seen. Sperm-derived polyploidy, which was observed only in the in vitro group, was independent of sperm age and occurred in 6.8% of the zygotes. These data provide support for the sperm-aging hypothesis and indicate, for the first time, an influence of sperm aging in the male genital tract on the X:Y ratio of conceptuses resulting from natural matings of chromosomally normal males.

Animals↗
PubMedDate not supplied

Morphological and biochemical changes of LLC-PK1 cells during adaptation to glucose-free culture conditions.

The established renal epithelial cell line LLC-PK1 retained in tissue culture several differentiated properties of renal proximal tubular cells. By adapting LLC-PK1 cells to glucose-free culture conditions, we recently succeeded in isolating a gluconeogenic strain of LLC-PK1 cells capable of growing in the absence of hexoses. In contrast to the parental wild type, the isolated strain expressed fructose-1,6-bisphosphatase activity and was, therefore, designated LLC-PK1-FBPase+. Besides the differences in glucose metabolism, the isolated gluconeogenic substrain differs form the parental wild type with respect to morphological appearance and the expression of apical membrane marker enzymes. LLC-PK1-FBPase+ cells display a drastic accumulation of autophagic vacuoles, disappearance of apical membrane alkaline phosphatase activity, and increased gamma-glutamyltranspeptidase activity. In order to find out whether or not a low alkaline phosphatase activity in combination with the enhanced formation of autophagic vacuoles is related to a change in apical membrane surface, we utilized a combined light and electron microscopic morphometric procedure to determine the absolute amount of organelle volumes and membrane surface areas. This stereologic approach shows that LLC-PK1-FBPase+ cells display a tenfold increase in the volume of autophagic vacuoles and the lysosomal compartment. Analysis of lysosomal enzyme activities, however, revealed no changes as compared to wild-type cells. The apical membrane surface of gluconeogenic cells was found to be increased by 80%. Karyotype analysis revealed that LLC-PK1 wild-type cells were diploid, whereas FBPase+ cells exhibited polyploidy with a high percentage of tetraploid nuclei. Culturing LLC-PK1-FBPase+ cells in the presence of 5 mM glucose does not abolish the morphological and biochemical changes described, indicating the stability of the FBPase+ strain.

Adaptation, Physiological↗
PubMed1990

Immortalization and neoplastic transformation of fetal rat intestinal epithelial cells: morphological and cytogenetic analysis, (proto)oncogene expression and effect of gamma-interferon on cell growth.

The permanent SLC-11 and -41 intestinal epithelial cells respectively immortalized by the E1A and large T oncogenes and their clonal derivatives showed a cytogenetic heterogeneity characterized by a near diploidy in SLC-11 and -12 cells and a generalized polyploidy in SLC-41 and -44 cells. Persistence of chromosome translocations and trisomy 3 were observed. The expression of the E1A oncogene in immortalized SLC-11 cells is associated with a strong repression of c-fos transcription during the exponential growth, as compared to the resting phase or to control rat fetal intestinal epithelial cells. The transcription of c-myc was also reduced in SLC-11 cells, especially in confluent cells. A complex relationship between the levels and size of the c-fos, c-myc mRNAs and the expression of the E1A oncogene was therefore observed in SLC-11 cells. Immortalized SLC-11 and -41 cells showed a remarkable growth inhibition in response to recombinant rat gamma-IFN. Neoplastic transformation by activated human Ha-ras in SLC-12T and -44 T cells confer resistance to the antigrowth effects of IFN. The combination of culture conditions using defined medium, membrane matrix (laminin, collagen, proteoglycans) and intestinal mesenchyme revealed the persistence of the undifferentiated phenotype of the E1A, large T-immortalized and Ha-ras-transformed SLC cells in vitro or in the nude mice. In association with the intestinal chick endoderm, SLC-11 cells possess some inductive properties on the differentiation of villi projections arising from the chick endoderm in vivo. In contrast, SLC-41 cells were induced to differentiate in enterocyte-like cells by the intestinal chick mesenchyme. The immortalized and Ha-ras-transformed SLC cells therefore constitute new models in the sequential analysis of the molecular and genetic mechanisms involved in the proliferation, differentiation and oncogene-mediated neoplastic transformation in gut. Further attempts in SLC cell differentiation have to be accomplished using chemical inducers for prolonged periods of time, or by transfection of intestinal epithelial cells using temperature- or glucocorticoid-inducible vectors.

Animals↗
PubMed1988

Chromosome analysis in patients with bladder tumor.

Cytogenetic analysis was performed in 80 patients with bladder tumor. The mitotic activity in patients with tumor G1, G2 and G3 degree of differentiation was not significantly different among them. Most of the patients with noninvasive tumor (G1) had a diploid or nearly diploid chromosome number, but all patients with invasive (G2 and G3) tumor had polyploidy. Marker chromosomes were found in 14 patients and 9 of them developed recurrence very soon. There is a good correlation between the recurrence rate and numerical or structural chromosomal abnormalities. This study emphasizes the importance of the chromosome analysis in the evaluation of therapy and prognosis for patients with bladder tumors.

Adult↗
PubMed1996

Nuclear deoxyribonucleic acid ploidy of testicular tumors: peculiar features and clinical significance.

To verify the usefulness of testicular DNA ploidy measurement, we tried some approaches to tumorous and nontumorous testes. Separation of paraffin-embedded specimens into single dissociated nuclei was performed by Hedley's technique and nuclei were stained with propidium iodide. Control nontumorous testes were clearly separated into the three-peak type with a high G2M percentage and the two-peak type with a low G2M percentage. Among testicular tumors, 25% (8 of 32) had a normal DNA diploid pattern, 15.6% (5 of 32) had an increased DNA tetraploid pattern including DNA polyploidy, and 59.4% (19 of 32) were DNA aneuploid. In detail, 26.3% (5 of 19) of seminomas and 23.1% (3 of 13) of nonseminomas were DNA diploid. Interestingly, seminomas showed a variety of DNA histogram profiles. Among DNA aneuploid tumors, the DNA index of a seminoma was significantly higher than that of a nonseminoma. Among patients who received curative orchiectomy, postoperative metastases did not occur in any of the 8 DNA diploid or 5 tetraploid tumors, but did occur in 4 (21.1%) of 19 DNA aneuploid tumors during an at least 6-year follow-up. Clinicopathological findings were not as predictable as DNA ploidy. Flow cytometry appeared to be useful to characterize testicular tumors.

Adolescent↗