scholarly journals Mechanisms involved in the induction of aneuploidy: the significance of chromosome loss

2000 ◽  
Vol 23 (4) ◽  
pp. 1077-1082 ◽  
Author(s):  
A.I. Seoane ◽  
A.M. Güerci ◽  
F.N. Dulout
Keyword(s):  
Cadmium Chloride ◽  
Potassium Dichromate ◽  
Chinese Hamster ◽  
Nickel Chloride ◽  
Chromosome Loss ◽  
X Rays ◽  
Chromosome Counting ◽  
Cadmium Sulfate ◽  
Chromium Chloride ◽  
Diploid Cells

The induction of aneuploidy by physical and chemical agents using different test systems was evaluated. The effect of X-rays, caffeine, acetaldehyde, ethanol, diethylstilbestrol, propionaldehyde, and chloral hydrate was studied by chromosome counting in Chinese hamster embryonic diploid cells. Aneugenic ability of cadmium chloride, cadmium sulfate, potassium dichromate, chromium chloride, nickel chloride, and nickel sulfate was assessed by means of anaphase-telophase analysis in Chinese hamster ovary cells. Chromosome counting in human fibroblasts (MRC-5 cell line) was employed to evaluate the effect of cacodilic acid, cadmium chloride, cadmium sulfate, and potassium dichromate. Finally, the induction of kinetochore-positive and kinetochore negative micronuclei by cadmium chloride, cadmium sulfate, potassium dichromate, chromium chloride, and nickel chloride was studied using CREST antibodies. When the effect of different agents was determined by chromosome counting, an increase of hypoploid but not of hyperploid cells was observed. Anaphase-telophase analysis showed that metal salts increased the frequency of lagging chromosomes. This finding has been confirmed by the increment of kinetochore-positive micronuclei using CREST antibodies. Therefore, chromosome loss could be considered as the main cause of induced aneuploidy.

scholarly journals Contribution to the validation of the anaphase-telophase test: aneugenic and clastogenic effects of cadmium sulfate, potassium dichromate and nickel chloride in Chinese hamster ovary cells

1999 ◽  
Vol 22 (4) ◽  
pp. 551-555 ◽  
Author(s):  
A.I. Seoane ◽  
F.N. Dulout
Keyword(s):  
Mitotic Index ◽  
Chinese Hamster Ovary ◽  
Potassium Dichromate ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Nickel Chloride ◽  
Cadmium Sulfate ◽  
Ovary Cells ◽  
Underlying Mechanisms ◽  
Chromatin Bridges

There is increasing evidence that aneuploidy during mitosis may be a factor in the etiology of somatic malignancy. The analysis of alterations in anaphase-telophase of mitosis is a useful test for evaluating the aneuploidogenic and clastogenic ability of chemicals. Several metals have been found to be carcinogenic to humans and animals. However, the underlying mechanisms remain unclear. In the present study the aneugenic and clastogenic abilities of cadmium sulfate, potassium dichromate and nickel chloride were analyzed using the anaphase-telophase test. Chinese hamster ovary (CHO) cells cultured for two cycles were treated with the desired compound for 8 h before cell harvesting. The frequency of cells with chromatin bridges, lagging chromosomes and lagging chromosomal fragments was scored. The mitotic index was determined by counting the number of mitotic cells per 1,000 cells on each coverslip and was expressed as a percentage of the number of mitotic plates. Statistical comparisons were done using the "G" method. Correlation and regression analyses were performed to evaluate variations of the mitotic index. Chromium and cadmium were clastogenic and aneugenic and increased the frequencies of the three types of aberrations scored; nickel had only aneugenic activity because it increased the frequency of lagging chromosomes. These results indicate that the anaphase-telophase test is sufficiently sensitive to detect dose-response relationships that can distinguish clastogenic and/or aneugenic activities and that the results obtained using the anaphase-telophase test were similar to those obtained by chromosome counting.

scholarly journals Protective effect of butylated hydroxytoluene (BHT) against the clastogenic acitivity of cadmium chloride and potassium dichromate in hamster ovary cells

1999 ◽  
Vol 22 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Claudia A. Grillo ◽  
Analía I. Seoane ◽  
Fernando N. Dulout
Keyword(s):  
Protective Effect ◽  
Chromosomal Aberration ◽  
Cho Cells ◽  
Cadmium Chloride ◽  
Potassium Dichromate ◽  
Chinese Hamster ◽  
Butylated Hydroxytoluene ◽  
Chromosomal Damage ◽  
Combined Treatments ◽  
Chromatin Bridges

The effect of butylated hydroxytoluene (BHT), a widely used food additive, on chromosomal alterations induced by cadmium chloride (CC) and potassium dichromate (PD) in Chinese hamster ovary (CHO) cells was studied both at metaphase and anaphase-telophase. CHO cells were cultured for 15-16 h in the presence of PD (6.0, 9.0 or 12.0 <FONT FACE="Symbol">m</font>M), BHT (1.0 <FONT FACE="Symbol">m</font>g/ml), or PD plus BHT as well as CC (0.5, 1.0 and 2.0 <FONT FACE="Symbol">m</font>M), BHT or CC plus BHT for the analysis of chromosomal aberrations. To perform the anaphase-telophase test, cells were cultured in cover glasses and treated 8 h before fixation with the same chemicals. An extra dose of CC (4 <FONT FACE="Symbol">m</font>M) was used in this test. Both metal salts significantly increased chromosomal aberration frequencies in relation to untreated controls, and to DMSO- and BHT-treated cells. Post-treatment with BHT decreased the yield of chromosomal damage in relation to treatments performed with CC and PD. However, chromosomal aberration frequencies were significantly higher than those of the controls. In the anaphase-telophase test, CC significantly increased the yield of lagging chromosomes with the four doses employed and the frequency of lagging fragments with the highest dose. In combined treatments of CC and BHT, frequencies of the two types of alterations decreased significantly in relation to the cells treated with CC alone. No significant variation was found in the frequencies of chromatin bridges. Significant increases of numbers of chromatin bridges, lagging chromosomes and lagging fragments were found in cells treated with PD. The protective effect of BHT in combined treatments was evidenced by the significant decrease of chromatid bridges and lagging chromosomes in relation to PD-treated cells. Whereas BHT is able to induce chromosomal damage, it can also protect against oxidative damage induced by other genotoxicants.

scholarly journals Parasexuality and Ploidy Change in Candida tropicalis

2013 ◽  
Vol 12 (12) ◽  
pp. 1629-1640 ◽  
Author(s):  
Riyad N. H. Seervai ◽  
Stephen K. Jones ◽  
Matthew P. Hirakawa ◽  
Allison M. Porman ◽  
Richard J. Bennett
Keyword(s):  
Sexual Reproduction ◽  
Candida Tropicalis ◽  
Culture Conditions ◽  
Sexual Cycle ◽  
Chromosome Loss ◽  
Parasexual Cycle ◽  
Content Type ◽  
Ploidy Changes ◽  
Diploid Cells

ABSTRACTCandidaspecies exhibit a variety of ploidy states and modes of sexual reproduction. Most species possess the requisite genes for sexual reproduction, recombination, and meiosis, yet only a few have been reported to undergo a complete sexual cycle including mating and sporulation.Candida albicans, the most studiedCandidaspecies and a prevalent human fungal pathogen, completes its sexual cycle via a parasexual process of concerted chromosome loss rather than a conventional meiosis. In this study, we examine ploidy changes inCandida tropicalis, a closely related species toC. albicansthat was recently revealed to undergo sexual mating.C. tropicalisdiploid cells mate to form tetraploid cells, and we show that these can be induced to undergo chromosome loss to regenerate diploid forms by growth on sorbose medium. The diploid products are themselves mating competent, thereby establishing a parasexual cycle in this species for the first time. Extended incubation (>120 generations) ofC. tropicalistetraploid cells under rich culture conditions also resulted in instability of the tetraploid form and a gradual reduction in ploidy back to the diploid state. The fitness levels ofC. tropicalisdiploid and tetraploid cells were compared, and diploid cells exhibited increased fitness relative to tetraploid cellsin vitro, despite diploid and tetraploid cells having similar doubling times. Collectively, these experiments demonstrate distinct pathways by which a parasexual cycle can occur inC. tropicalisand indicate that nonmeiotic mechanisms drive ploidy changes in this prevalent human pathogen.

scholarly journals Survival Curves and Age Response Functions for Chinese Hamster Cells Exposed to X-Rays or High LET Alpha-Particles

1972 ◽  
Vol 52 (1) ◽  
pp. 88 ◽  
Author(s):  
E. J. Hall ◽  
W. Gross ◽  
R. F. Dvorak ◽  
A. M. Kellerer ◽  
H. H. Rossi
Keyword(s):  
Chinese Hamster ◽  
Alpha Particles ◽  
X Rays ◽  
Response Functions ◽  
Survival Curves ◽  
Chinese Hamster Cells ◽  
High Let

Coordinate induction of metallothioneins I and II in rodent cells by UV irradiation

1988 ◽  
Vol 8 (11) ◽  
pp. 4716-4720
Author(s):  
A J Fornace ◽  
H Schalch ◽  
I Alamo
Keyword(s):  
Sequence Analysis ◽  
Uv Irradiation ◽  
Time Course ◽  
Human Fibroblasts ◽  
Chinese Hamster ◽  
Cdna Clones ◽  
X Rays ◽  
General Stress Response ◽  
Rapid Induction ◽  
Kinetics Of

Sequence analysis of Chinese hamster V79 lung fibroblast cDNA clones, which code for UV radiation-inducible transcripts, revealed that many of the clones corresponded to metallothioneins (MTs) I and II. A third cDNA clone, DDIU4, was found also to code for a similar-size UV-inducible transcript which was unrelated to MT by both sequence analysis and kinetics of induction. MTI and MTII RNAs rapidly increased in V79 cells within 1 h after UV irradiation, and maximum induction was seen by 4 h. This rapid induction of MT RNA by UV irradiation was not observed in human fibroblasts. MTI and MTII were coordinately induced in both time course and dose-response experiments, although the induction of MTII, up to 30-fold, was three to four times greater than that of MTI. The induction of MT did not appear to be a general stress response, since no increase occurred after exposure to X rays or H2O2.

Segregation of recessive phenotypes in somatic cell hybrids: role of mitotic recombination, gene inactivation, and chromosome nondisjunction

1981 ◽  
Vol 1 (4) ◽  
pp. 336-346
Author(s):  
C E Campbell ◽  
R G Worton
Keyword(s):  
Somatic Cell ◽  
Chinese Hamster ◽  
Mitotic Recombination ◽  
Chinese Hamster Cell ◽  
Gene Inactivation ◽  
Chromosome Loss ◽  
Resistance Locus ◽  
Chromosome 2 ◽  
Somatic Cell Hybrids ◽  
Cell Hybrids

Somatic cell hybrids heterozygous at the emetine resistance locus (emtr/emt+) or the chromate resistance locus (chrr/chr+) are known to segregate the recessive drug resistance phenotype at high frequency. We have examined mechanisms of segregation in Chinese hamster cell hybrids heterozygous at these two loci, both of which map to the long arm of Chinese hamster chromosome 2. To follow the fate of chromosomal arms through the segregation process, our hybrids were also heterozygous at the mtx (methotrexate resistance) locus on the short arm of chromosome 2 and carried cytogenetically marked chromosomes with either a short-arm deletion (2p-) or a long-arm addition (2q+). Karyotype and phenotype analysis of emetine- or chromate-resistant segregants from such hybrids allowed us to distinguish four potential segregation mechanisms: (i) loss of the emt+- or chr+-bearing chromosome; (ii) mitotic recombination between the centromere and the emt or chr loci, giving rise to homozygous resistant segregants; (iii) inactivation of the emt+ or chr+ alleles; and (iv) loss of the emt+- or chr+-bearing chromosome with duplication of the homologous chromosome carrying the emtr or chrr allele. Of 48 independent segregants examined, only 9 (20%) arose by simple chromosome loss. Two segregants (4%) were consistent with a gene inactivation mechanism, but because of their rarity, other mechanisms such as mutation or submicroscopic deletion could not be excluded. Twenty-one segregants (44%) arose by either mitotic recombination or chromosome loss and duplication; the two mechanisms were not distinguishable in that experiment. Finally, in hybrids allowing these two mechanisms to be distinguished, 15 segregants (31%) arose by chromosome loss and duplication, and none arose by mitotic recombination.

scholarly journals Polyploid Formation via Chromosome Duplication Induced by CTP:Phosphocholine Cytidylyltransferase Deficiency and Bcl-2 Overexpression: Identification of Two Novel Endogenous Factors

2005 ◽  
Vol 53 (6) ◽  
pp. 725-733 ◽  
Author(s):  
You-Jun Shen ◽  
Cynthia J. DeLong ◽  
Francois Tercé ◽  
Timothy Kute ◽  
Mark C. Willingham ◽  
...  
Keyword(s):  
Dna Content ◽  
Chinese Hamster ◽  
B Cell Lymphoma ◽  
Negative Regulator ◽  
Ovary Cell ◽  
Endogenous Factors ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Polyploid Formation ◽  
Cellular Dna ◽  
Diploid Cells

Polyploidy is a profound phenotype found in tumors and its mechanism is unknown. We report here that when B-cell lymphoma gene-2 (Bcl-2) was overexpressed in a Chinese hamster ovary cell line that was deficient in CTP:phosphocholine cytidylyltransferase (CT), cellular DNA content doubled. The higher DNA content was due to a permanent conversion from diploid cells to tetraploid cells. The mechanism of polyploid formation could be attributed to the duplication of 18 parental chromosomes. The rate of conversion from diploid to tetraploid was Bcl-2 dose dependent. The diploid genome was not affected by Bcl-2 expression or by CT deficiency alone. Endogenous CT or expression of recombinant rat liver CTα prior to Bcl-2 expression prevented the formation of polyploid cells. This conversion was irreversible even when both initiating factors were removed. In this study, we have identified Bcl-2 as a positive regulator and CTα as a negative regulator of polyploid formation.

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