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PubMed1985

Effects of diethylstilboestrol-dipropionate on SCEs, micronuclei, cytotoxicity, aneuploidy and cell proliferation in maternal and foetal mouse cells treated in vivo.

The effect of diethylstilboestrol-dipropionate on the frequency of SCEs and micronuclei, cytotoxicity, aneuploidy and cell proliferation rates of foetal liver and maternal bone marrow cells following exposure of pregnant mice was measured. An increase in the number of aneuploid and polyploid cells was observed in both tissues. There was no effect on micronuclei frequency, SCE frequency, or cell proliferation rate.

Abortion, Spontaneous↗

PubMed1988

1,6-Dinitropyrene causes spindle disturbances and chromosomal damage in V79 Chinese hamster cells.

We have investigated the cytogenetic effect of 1,6-dinitropyrene (1,6-DNP) in Chinese hamster V79 cells. The chemical caused a dose-dependent increase in the incidence of initial and full C-mitoses, polyploid mitoses, ana-telophases with lagging chromosomes, non-disjunction and multipolar configurations, in a range of 0.05-5 microM. These findings indicate that 1,6-DNP interferes with the functioning of the spindle apparatus in V79 cells. Early signs of spindle disturbances were seen at 1,6-DNP concentrations which only moderately reduced cell growth and division. Analysis of structural chromosomal aberrations revealed the appearance of chromatid-type aberrations with open breaks and exchanges accompanied by gaps. The results indicate that 1,6-DNP is both a spindle-disturbing and a clastogenic agent in V79 cells.

Animals↗

PubMed1990

Chromosomal aberrations, sister-chromatid exchanges, cell-cycle kinetics and satellite associations in human lymphocyte cultures exposed to vanadium pentoxide.

Treatment of human lymphocytes with vanadium pentoxide (V2O5) was not found to increase the frequency of structural chromosomal aberrations (CA) and sister-chromatid exchanges (SCE). However, V2O5 significantly increased polyploid cell frequency; also, the mitotic index (MI) was significantly decreased, and the average generation time (AGT) was significantly increased. Finally, the frequency of cells with satellite associations (SA), the frequency of SA per cell, and the frequency of chromosomes associated increased in treated cultures.

Adult↗

PubMed1990

Induction of chromosomal aberrations in male mouse germ cells by uranyl fluoride containing enriched uranium.

Cytogenetic damage induced by a wide range of concentrations of uranyl fluoride injected into mouse testes was evaluated by determining the frequencies of chromosomal aberrations in spermatogonia and primary spermatocytes. Breaks, gaps and polyploids were observed in spermatogonia. The frequencies of the significant type of aberration, breaks, were induced according to the injected doses of uranyl fluoride. Primary spermatocytes were examined for fragments, univalents and multivalents. The multivalents observed in this study resulted either from chromatid interchanges or from reciprocal translocations. The reciprocal translocations were induced in spermatogonia and recorded in primary spermatocytes. For primary spermatocytes the incidence of aberrant cells largely depended on the administered dose. Sampling time after treatment could affect the frequencies of chromosomal aberrations in male mouse germ cells.

Animals↗

PubMed1994

Cytogenetic effects on human lymphocytes of a mixture of fifteen pesticides commonly used in Italy.

Lymphocytes obtained from 5 healthy donors were incubated with a mixture of 15 pesticides commonly found in foods of central Italy (dithiocarbamates (20.7%), benomyl (19.6%), thiabendazole (14.9%), diphenylamine (14.4%), chlorthalonil (13.1%), procymidone (8.0%), methidathion (2.3%), chlorpyrifos-ethyl (2%), fenarimol (1.9%), parathion-methyl (1%), chlorpropham, parathion, vinchlozolin, chlorfenvinphos and pirimiphos-ethyl (< 1%)). The percent of each pesticide in the mixture was proportional to its average concentration in foods. Incubated with the lymphocytes at a concentration of 1-20 micrograms/ml the pesticide mixture did not induce significant variations in the number of hypodiploid, hyperdiploid and polyploid cells or in the number of chromosome and chromatid aberrations. On the contrary, we observed a dose-dependent increase in the number of nonsynchronous centromeric separations which reached the level of 37.9% at 20 micrograms/ml of pesticide mixture in the incubation medium. This effect was not observed when benomyl was excluded from the mixture. These data show that the removal of benomyl could decrease the toxicity of pesticide residues present in human food.

Adult↗

PubMed1982

Substance P enhances cation permeability of neuronal cell lines.

Substance P stimulated the uptake of guanidinium in neuroblastoma X glioma hybrid cells and neuroblastoma cells but not in polyploid glioma cells. Guanidinium has previously been shown to pass the action potential Na+ channel in the two neuronal cell lines. Half-maximal stimulation was reached at 3 microM substance P and, with the hybrid cells, a saturation was seen above 10 microM. The analogue (D-Pro2,D-Trp7,9)-substance P, recently described as a substance P antagonist, caused a stimulation of guanidinium uptake comparable to that seen in the presence of substance P and did not inhibit the stimulation exerted by substance P. The pharmacological properties of the substance P-activated ion channel were investigated. Tubocurarine, phentolamine and propranolol blocked the substance P-stimulated guanidinium uptake with half-maximal inhibitory concentrations of 0.5, 5 and 50 microM. A similar characteristics has been found previously with the veratridine-activated Na+ channel in the cell lines investigated here. Peptides structurally related to substance P such as physalaemin and eledoisin, or others such as neurotensin, bradykinin, D-Ala2, Met5-enkephalinamide and ACTH(1-24) did not affect guanidinium uptake. In view of the high concentrations of substance P required for eliciting an effect in the cell lines, the involvement of specific receptors is questioned. A direct interaction of the peptide with the action potential Na+ channel is discussed.

Animals↗

PubMed1982

Ribosomal RNA sequence conservation and gene number in the larval brine shrimp.

The haploid genome size of Artemia is determined to be about 0.9 X 10(12), as evidenced both by Feulgen microspectrophotometry of individual diploid class nuclei, which are but one of five polyploid classes present within the larvae, and by analysis of the reassociation kinetics of the isolated single copy DNA component. Polysomes isolated from 24-h incubation stage larvae contain an average of 10 ribosomes per messenger RNA molecule. Their rRNAs are found to have sedimentation coefficients of 18 S and 26 S, corresponding to molecular weights of 0.70 X 10(6) and 1.40 X 10(6), respectively, as determined by polyacrylamide electrophoresis and also by sucrose density centrifugation. Denaturation in glyoxal followed by agarose gel electrophoresis shows that unlike deuterostome rRNAs, Artemia 26 S rRNA contains a cryptic nick about midway in the molecule, which is not found in the 18 S molecule. Isolated rRNAs were labelled in vitro with 125I and hybridized with filter-immobilized DNA to saturation, which occurred at 0.051% for Xenopus, and at 0.074% for Artemia. From these results, it is calculated that in the haploid Artemia genome there are about 320 copies of the (18 S + 26 S) ribosomal RNA genes. Reciprocal heterologous hybridizations between these two species show that they share about 30% homology between their rDNA coding sequences.

Animals↗

PubMed1990

Spatial and temporal distribution of a Drosophila melanogaster embryonic variable nuclear antigen.

A polyclonal antibody has been prepared that specifically recognises a nuclear protein antigen in Drosophila embryos. During development, the antigen appears initially to be uniformly distributed but by nuclear division cycle 10 is seen to accumulate in nuclei in a manner suggesting that it is destroyed or becomes modified upon transition from S- to M phase of the nuclear division cycle. This conclusion is supported by the observed disappearance of the antigen from the postblastoderm nuclei in a manner that reflects the pattern of the first asynchronous postblastoderm cell division and persistence in the polyploid nuclei of the amnioserosa that do not undergo further cell or nuclear division. In Western blot experiments, the antibody detects specifically a 105 kDa nuclear protein that probably corresponds to the antigen detected in embryos by immunocytochemical means.

Animals↗

PubMed1986

Influence of dietary protein restriction on cell number, cell size and growth of mouse organs during the course of aging.

Groups of male Swiss albino mice on diets of 4%, 8% and 26% protein were sacrificed at 6, 12, 42 and 84 weeks of age to determine the extent to which cell number and cell size were influenced by dietary protein restriction in the course of aging. The results show that cell number is reduced by low protein diets only in liver and kidney: that is, in expanding cell populations. Cell number in the static cell populations of brain and heart was not influenced by diet. Increase in organ size is brought about by a variety of mechanisms. Heart size increases in mice on a higher protein diet by means of increase in cell size; a cellular hypertrophy. Liver size increases both through cell addition and formation of larger polyploid cells. The kidney was the only organ in which there was a continuous addition of new cells of constant size throughout the life span. Dietary protein restriction reduced the rate of cell size increase and of growth. Although it slowed the growth process, it did not alter any of the aging or growth patterns.

Animals↗

PubMedDate not supplied

Morphological aspects of aging liver: half a century of progress in Japan.

The most important morphological aspects of the physiological changes of the liver with age are decreases in the numbers of hepatocytes and their mitochondria, coupled with increases in their volumes. The latter is considered to partially compensate for the decrease in numbers of hepatocytes and mitochondria, but leads to a more limited reserve capacity and thus to a condition in which liver function can be more readily exhausted. The binuclearity and polyploidization of the hepatocytes increase with age and are considered to be due to inhibition of their cell division process. Our studies on the parabiosis between young and old rats and mice, on the implantation of isolated hepatocytes in the spleens of rats of different ages, and on the regenerative process after partial hepatectomy in rats of different ages, suggested the existence of humoral inhibitory factor(s) for the division of the cells and their mitochondria. Morphological studies on the native and Hawaiian Japanese, as well as on the USA Caucasians and the Costa Rican Latinos revealed that a difference in the process of the age-related decrease in hepatocyte number among different ethnicities is mainly due to differences in nutritional conditions rather than to genetic factors. Experimental studies are now being carried out on the effect(s) of various dietary conditions on age-related changes of the liver, and the results obtained support the findings of the geographical studies.

Journal Article↗

PubMed1986

Herpes simplex virus gene products involved in the induction of chromosomal aberrations.

The effect of short-term herpes simplex virus type 1 (HSV-1) infection on chromosomes of human diploid fibroblasts was examined. In addition to chromosomal breaks, gaps and pulverization, three kinds of cytogenetic damage (double minutes, polyploidy and endoreduplication) not yet reported following productive infection with HSV or other animal viruses were frequently observed. Consistent with previous studies suggesting that the expression of immediate-early and/or early viral gene products is required for the induction of chromosomal damage, was the observation that cells infected at the nonpermissive temperature with HSV-1 temperature-sensitive mutants defective in the gene for the immediate-early transcriptional regulatory protein, ICP4, and three early viral gene products--DNA polymerase (pol), the major HSV DNA-binding protein (ICP8) and an HSV-2 mutant defective in alkaline nuclease--exhibited altered patterns of chromosomal damage relative to the effects of wild-type virus on infected cells. These findings suggest a direct or indirect role for all four gene products in the induction of chromosomal damage. In cells infected with wild-type virus for 4 h or longer, HSV proved to be a more potent mitotic arresting agent than colcemid. Moreover, studies with selected mutants indicate that HSV pol specifically may be involved in mitotic arrest. Additionally, in cells infected at the non-permissive temperature with a pol mutant, the number of polyploid metaphases was reduced 4-fold relative to that seen in wild-type virus-infected cells suggesting a role for HSV pol in the amplification of cellular DNA.

Cell Line↗

PubMed1996

Induction of polyploidy in adenovirus E1-transformed cells by the mitotic inhibitor colcemid.

Adenovirus-transformed cells were tested for their ability to synthesize DNA in the presence of cell cycle inhibitory drugs. We show that transformed cells are completely resistant to the mitotic inhibitor colcemid, partly resistant to lovastatin, mimosine, aphidicolin and genistein but not to hydroxyurea or thymidine. When treated with colcemid, AdE1-transformed cells continue to synthesize DNA but do not divide and, therefore, become highly polyploid. This effect is dependent on the presence of both E1A and E1B.

Adenovirus E1 Proteins↗

PubMed1989

SIMREP: a program simulating differential DNA replication.

During endoreplication, different organisms in different taxa carry out DNA syntheses without nuclear division. The result of such endocycles is either a polyploid nucleus or a polytene architecture of the chromosomes. Since not all sequences of the genome may be reduplicated simultaneously and to the same extent, endocycles provide an opportunity for primary cell differentiation at the DNA level as a result of DNA amplification or underreplication. We have designed a numerical model which simulates differential endoreplications. The program SIMREP is written in TURBO PASCAL 4.0 and can be executed on a PC/XT/AT with MS-DOS greater than or equal to 2.0. It uses diploid DNA contents derived from meiotic or mitotic nuclei together with data on amounts of DNA present after a given number of endocycles. SIMREP can be applied to genomes containing arbitrary numbers of chromosomes (maximum N = 24) to model details of their replication behaviour. It is also useful in analysing differential replication of single genes. The application of SIMREP is illustrated with two examples. (1) Female and male specific types of underreplication were found in the chironomid midge Prodiamesa olivacea. The heterosomes which appear homomorphic in metaphases were identified by their differential polytenization. (2) The Y chromosome of Drosophila nasutoides was assessed to ascertain whether its replication is regulated in parallel with, or independently from the large chromosome pair 4.

Animals↗

PubMed1993

The occurrence, role and evolution of chromatin diminution in nematodes.

Chromatin diminution takes place in presomatic cells of some parasitic nematodes during early development. This phenomenon may play an important role in somatic cell differentiation, since the somatic cells of these species undergo an extensive genome reorganization during development via chromatin diminution and polyploidization, as explained here by Clara Goday and Sergio Pimpinelli.

Journal Article↗

PubMed1994

Immunogenicity of foot-and-mouth disease virus grown in BHK-21 suspension cells. Correlation with cell ploidy alterations and abnormal expression of the alpha 5 beta 1 integrin.

BHK-21 suspension cells were characterized with regard to genetic and phenotypic features which might adversely affect the immunogenic properties of foot-and-mouth disease virus (FMDV) grown therein. A positive correlation was found between number of passages in suspension culture and both prevalence of polyploid cells and reduced cell growth on surfaces. Suspension cells also revealed differences in the expression of RGD-specific integrins and, in particular, of alpha 5 beta 1, which was shown to work as an FMDV receptor structure. These features, along with the notable instability of a few non-structural FMDV A5 proteins in infected cells, outline a new scenario, in which the reduced immunogenicity of FMDV might be accounted for by defined negative influences of the cell environment on viral replication.

Amino Acid Sequence↗

PubMed1988

Human megakaryocytopoiesis: in vitro regulation and characterization of megakaryocytic precursor cells by differentiation markers.

Understanding of human megakaryopoiesis has been improved by in vitro culture techniques, characterization of platelet proteins as differentiation markers and megakaryocyte purification. A continuum of megakaryocytic cells ranging from the CFU-MK (cell capable of proliferation) to the platelet has been demonstrated. CFU-MK is a heterogeneous population of cells which do not express platelet proteins other than platelet GP IIb and IIIa which may be present in low concentration. The main platelet proteins are synthesized later during differentiation of a 2N cell, just before the polyploidization process. Several homogeneous growth factors GM-CSF, interleukin 3 and erythropoietin are able to sustain human megakaryocyte colony formation. However, no specific MK-CSF has yet been purified. Purification of factors active on late stages of differentiation has proved difficult when using in vivo techniques to test their activity. However, recently such a factor has been purified to homogeneity by testing its action on the biosynthesis of PF4 by megakaryocytes. A negative regulation of megakaryopoiesis has been suggested by the inhibition of MK-colony formation by platelet products especially TGF-beta. A better understanding of human megakaryopoiesis may be of importance as it may allow modifications of platelet production in a clinical setting.

Hematopoiesis↗

PubMed1983

The effect of N-formylleurosine on DNA synthesis of Ehrlich ascites tumor.

Some of the vinca alkaloids are well known and widely used in clinical practice, in spite of their numerous side-effects. For the elimination of untoward side-effects semi-synthetic alkaloids have been produced. This work reports on N-formylleurosine (N-F-Leu), one of these agents. Its antitumour activity is, in many respects, similar to that of other, presently used vinca alkaloids; it causes metaphase block, the appearance of multinucleated cells and polyploidization. In addition to these effects, N-F-Leu induces significant new phenomena, namely, changes in the activity of thymidine kinase, a key enzyme of DNA synthesis as well as in thymidine incorporation, and reduces the proportion of cells in S phase in a relatively short period of time after treatment: 24-29 hr. Based on these observations, the reevaluation of the mechanism of action of vinca alkaloids has become possible.

Animals↗

PubMed1986

Growth and ploidy of human osteosarcoma xenografts in serial passage in nude mice.

Six human osteosarcoma tumors have been transplanted to and maintained as xenografts in serial passage in nude mice. The xenografts, characterized by growth rate, histologic appearance, and DNA flow cytometric data, are now in the 6-17 passages in mice. Histologic appearances and growth rates of the xenografts were unchanged through all passages except for one xenograft in which the growth rate doubled in passage 3. All six tumors had hyperploid DNA contents. The ploidy levels were unchanged, compared to their original tumors, in all passages of five xenografts. One xenograft, concomitantly with the increase in growth rate, also doubled the ploidy from 2.8 to 5.6C. There was a good agreement between the proportion of S-phase cells and mitotic indices of the six xenografts. The growth rate, depending also on cell loss, was less related to the proliferative activity of the xenografts. It was concluded that osteosarcomas have a stable aneuploid DNA content in nude mice, but polyploidization can occur after a number of passages.

Animals↗