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F Pacchierotti

Publications and source records attributed to F Pacchierotti.

At least 37 records · Page 2Linked to original sources
PubMed1996

Flow cytometric and histological assessment of 1,2:3,4-diepoxybutane toxicity on mouse spermatogenesis.

The effects of diepoxybutane (DEB) on mouse reproductive cells have been investigated by flow cytometric and histological description of testicular cell populations and alterations of sperm chromatin packaging. Mice were treated with single intraperitoneal injections of DEB, with doses ranging between 8.5 and 78 mg/kg (100-900 microM), and were killed after 7, 14, 21, 28 or 35 d. Dose-dependent reductions of tetraploid cells, round spermatids, and elongated spermatids were detected at 7, 21, and 28 d, respectively, reflecting cytotoxic damage on the differentiating spermatogonia compartment. The dose necessary to reduce the number of differentiating spermatogonia to half the control value was estimated equal to 650 microM or 55 mg/kg. Stem cells were not affected by this treatment. Histological section of seminiferous tubules showed depletion of spermatids and reduction of the secondary spermatocyte layers. In addition, a high although not statistically significant frequency of sperm with altered chromatin packaging was detected after DEB treatment. DEB is one of the key metabolites of butadiene, which is a compound of high environmental and occupational concern. These results contribute to the assessment of the reproductive health impact of butadiene in humans.

Animals↗
PubMed1996

Genotoxicity of trophosphamide in mouse germ cells: assessment of micronuclei in spermatids and chromosome aberrations in one-cell zygotes.

The genotoxicity of trophosphamide (TP) in mouse germ cells was assessed by the cytogenetic analysis of micronuclei in spermatids and chromosome aberrations in one-cell zygotes and compared with the genotoxicity in somatic cells evaluated by the micronucleus reticulocyte assay. Single acute doses of 50, 75, 100 and 150 mg/kg were studied after i.p. injection. TP was only weakly mutagenic for preleptotene spermatocytes-differentiating spermatogonia, but clear-cut cytotoxic effects were demonstrated after treatment of these cells by a dose-dependent reduction of the ratio between Golgi and cap phase spermatids. Effects induced in post-meiotic stages were estimated, after mating the treated males with untreated superovulated females, by the frequencies of zygotes with chromosome aberrations: a peak of genetic damage was detected in late spermatids, with as many as 55% zygotes with aberrations, but spermatozoa and early spermatids were also clearly affected. When compared with matched solvent-injected controls, the lowest effective dose in spermatozoa and late spermatids was 100 mg/kg, although the 3- to 4-fold increases detected at 50 mg/kg were also statistically significant when compared with a pool of laboratory controls. In peripheral blood reticulocytes, the micronucleus frequencies were increased by 3-20 times the respective baseline values in the individual animals. A marked cytotoxic effect on bone marrow cells was revealed by the reduction of the proportion of early reticulocyte stages, which dropped to 20% of the control value at 150 mg/kg. Both genotoxic and cytotoxic effects were higher in bone marrow than in germ cells of the same animals, pointing to a generalized higher susceptibility of somatic cells to TP, possibly related to chemical distribution and target organ accessibility. The accurate description of stage- and dose-effect relationships in germ cells of experimental models is crucial for genetic risk assessment after chemical exposure. The approaches applied in this study may contribute to this goal.

Animals↗
PubMed1996

The centromere as a target for the induction of chromosome damage in resting and proliferating mammalian cells: assessment of mitomycin C-induced genetic damage at kinetochores and centromeres by a micronucleus test in mouse splenocytes.

The cytokinesis-block micronucleus assay (MN) on murine splenocytes was used for the estimation of chromosome damage in a resting cell population in vivo that can be induced to proliferate in vitro. Mitomycin C at different doses (10(-8), 6 x 10(-8), 10(-7), 6 x 10(-7) and 10(-6)M) was used to induce cytogenetic damage in resting and cycling splenocytes. Antikinetochore antibodies (CREST) and two-colour fluorescence in situ hybridization (FISH) with minor and major satellite DNA were applied. These approaches allowed the detailed characterization of the mechanisms by which MN originates, since it was possible to identify breaks induced in pericentric heterochromatic (resulting in MN containing the major but not the minor satellite DNA) or detachment/disruption of kinetochore (resulting in different frequencies of MN containing kinetochore or both probes). Based on the evidence that resting and cycling mouse splenocytes are characterized by different spatial distribution of centromeric regions, the hypothesis was tested that the damage induced by mutagens at centromeres is influenced by the phase of the cell cycle in which the cells are treated. Data presented here show that resting and cycling splenocytes are both sensitive to mitomycin C action, and indicate that this compound has an aneugenic potential, besides its strong clastogenic activity. In particular, results obtained after CREST and FISH characterization of MN differed when cells were treated during proliferation, suggesting a disruption/detachment of kinetochores induced by mitomycin C at this cell stage. Furthermore, under the same treatment condition the proportion of MN containing the major satellite DNA only was greater than expected on the basis of random breakage at this site. Treatment of resting cells produced aneugenic damage, but without evidence of disruption/detachment of kinetochores or preferential breakage at the centromere. These results indicate that the amount and type of chromosome damage induced by mitomycin C in mouse splenocytes differ in relation to the proliferative status of treated cells.

Animals↗
PubMed1995

Susceptibility to vinblastine-induced aneuploidy and preferential chromosome segregation during meiosis I in Robertsonian heterozygous mice.

Chromosome segregation at meiosis I was studied in oocytes and spermatocytes of four different Robertsonian (Rb) heterozygous mouse stocks by cytogenetic analysis of meiotic products. Two Rb heterozygotes spontaneously yielded high frequencies of unbalanced oocytes. In one case, Rb(2.18)Rma, the excess hyperploidy was mainly accounted for by nondisjunction of normal bivalents, suggesting a generalized impairment of meiotic segregation. In each stock, frequencies of hyperploid spermatocytes were either not significantly different or significantly lower than the corresponding frequencies in the oocytes. This confirmed the greater risk of segregational errors in female than in male carriers of the same Rb metacentric. The hypothesis that an error prone system of meiotic segregation, such as the trivalent configuration of single Rb heterozygous oocytes, could be hypersensitive to chemically induced malsegregation was tested by injecting Rb heterozygous females with low doses of vinblastine (VBL). An intraperitoneal injection of 0.06 or 0.09 mg/kg VBL before the first meiotic division significantly increased the spontaneous frequency of hyperploid oocytes, inducing segregational errors of both the trivalent and normal bivalents. The comparison of these data with VBL effects in B6C3F1 mice showed that single Rb heterozygous oocytes are more sensitive to VBL-induced meiotic aneuploidy than oocytes with a standard karyotype. Although segregation distortion has been repeatedly shown in the progeny of Rb heterozygous mice with a significant excess of all telocentric balanced offspring, it has never been demonstrated whether this is a primary event occurring during meiotic segregation or a consequence of selective postconceptional death. In this study, we showed that preferential segregation occurred during female meiosis in all the Rb stocks tested. When segregation distortion was analyzed separately in balanced and unbalanced oocytes, the latter did not show preferential segregation, suggesting that, when the two telocentrics segregated from each other, then the metacentric was randomly directed to the ovum or the polar body.

Aneuploidy↗
PubMed1995

Clastogenicity of diepoxybutane in bone marrow cells and male germ cells of mice.

The bifunctional metabolite of 1,3-butadiene, 1,2:3,4-diepoxybutane (DEB), was tested in the mouse bone marrow micronucleus assay and in male mouse germ cell tests, namely the analysis of first cleavage divisions and the dominant lethal assay. All experiments were performed with single intraperitoneal treatment of the animals. In the micronucleus test, DEB doses of 4.5, 9.0, 18.0 and 36.0 mg/kg body weight were tested at a sampling interval of 24 h for bone marrow. The dose response for the induction of micronuclei in polychromatic erythrocytes was linear with the lowest effective dose of 9.0 mg/kg body weight. No sensitivity difference was observed between male and female mice. the cytogenetic analysis of first cleavage division chromosomes was performed after treatment of male mice with 17, 26, 34, 43 and 52 mg/kg body weight of DEB and mating the males to hormonally stimulated females on days 7, 14, 21 and 28 after treatment. The two higher doses caused general toxicity evidenced by the poor mating behavior of the males. Only 13 and 20% of the mated females were fertilized on day 7 after treatment of the males with 43 and 52 mg/kg body weight of DEB, respectively. An increased number of unfertilized oocytes was obtained from fertilized females on day 7 after treatment of the males with 34 mg/kg body weight of DEB. With a dose of 26 mg/kg body weight, it was demonstrated that chromosomal aberrations were only induced in spermatozoa (mating on day 7 after treatment) while spermatids (mating on days 14 and 21) and spermatocytes (mating on day 28) were not susceptible to the clastogenic effect of DEB. The response in spermatozoa in the dose range 17-34 mg/kg body weight was linear up to 26 mg/kg body weight and reached a plateau thereafter. The results of the dominant lethal experiments performed in the dose range 18-54 mg/kg body weight gave results similar to the cytogenetic study. With the highest dose tested, the toxicity and cytotoxicity during the first 8 mating days after treatment dramatically reduced the number of pregnant females and, consequently, the total implantations, so that no significant dominant lethal effect could be assessed. During mating days 9-12 (treated late spermatids), a significant dominant lethal effect was observed. With the two lower doses (18 and 36 mg/kg body weight), the dominant lethal effect was restricted to spermatozoa. The good correlation of the chromosomal aberrations with dominant lethal mutations confirms the chromosomal origin of dominant lethal effects. The clastogenic effect of DEB in somatic cells and in germ cells of mice was of the same order of magnitude.

Animals↗
PubMed1994

Acrylamide-induced chromosomal damage in male mouse germ cells detected by cytogenetic analysis of one-cell zygotes.

Within a project coordinated by the Commission of the European Communities for the detection of germ cell mutagens, the cytogenetic analysis of first-cleavage metaphases was carried out to detect chromosomal damage induced by acrylamide (AA) in meiotic and postmeiotic stages of mouse spermatogenesis. Male mice were intraperitoneally injected with single acute doses of 75 or 125 mg/kg or treated with five daily injections of 50 mg/kg and mated either 7 or 28 days after the end of treatment. Chromosomal aberrations were scored in C-banded metaphases prepared from one-cell zygotes by a mass harvest technique. AA treatment of late spermatids-spermatozoa resulted in significant increases of structural aberrations at all doses tested. The data could be fitted to a curvilinear regression and a doubling dose of 23 mg/kg was calculated. The large majority of observed aberrations were of the chromosome type, including dicentrics, rings and translocations, in agreement with a mechanism of chromosomal damage mediated through the alkylation of DNA-associated protamines. Even though the frequency of aberrations 28 days after treatment was not significantly higher than the control value, the presence of multiple rearrangements in two cells suggested that AA might also have a minor effect on spermatocytes. The results of the cytogenetic analysis of first cleavage metaphases agreed well both qualitatively and quantitatively with the outcome of dominant lethal and heritable translocation assays. AA-induced cytotoxicity was monitored by flow cytometric DNA content analysis of testicular cells. By this method, a dose-dependent depletion of mature spermatids after treatment of spermatogonia and a toxic effect upon primary spermatocytes were detected.

Acrylamide↗
PubMed1994

Report from the working group on the in vivo mammalian bone marrow chromosomal aberration test.

The following summary represents a consensus of the working group, except where noted. The goal of this working group was to identify the minimal requirements needed to conduct a scientifically valid and practical in vivo chromosomal aberration assay. For easy reference, the items discussed are listed in the order in which they appear in OECD guideline 475. Specific disagreement with the current and/or proposed OECD guideline is presented in the text. Introduction, purpose, scope, relevance, application, and limits of test: This test would not be appropriate in situations where there was sufficient evidence to indicate that the test article or reactive metabolites could not reach the bone marrow. Test substances: Solid and liquid test substances should be dissolved, if possible, in water or isotonic saline. If insoluble in water/saline, the test substance should be dissolved or homogeneously suspended in an appropriate vehicle (e.g., vegetable oil). A suspension was not considered suitable for an intravenous injection. The use of dimethyl sulfoxide as an organic solvent was not recommended. The use of any uncommonly used solvent/vehicle should be justified. Freshly prepared solutions or suspensions of the test substance should be employed unless stability data demonstrate the acceptability of storage. Selection of species: Any commonly used rodent species was deemed acceptable but rats or mice were preferred, with no strain preference. Number and sex: A consensus could not be reached as to the requirement for both sexes versus one sex in this assay. It was suggested that a single sex should be used unless pharmacokinetic and/or toxicity data indicated a difference in metabolism and/or sensitivity between males and females. The size of the experiment (i.e., number of cells per animal, number of animals per treatment group) should be based on statistical considerations. Lacking a formal analysis, it was agreed that at least 100 metaphase cells should be scored per animal while at least five animals of any one sex should be evaluated per treatment group. Recently, a formal analysis of the numbers of cells to score per animal and numbers of animals to score per treatment group was conducted at a workshop on statistics for in vivo mutagenicity tests (Adler et al., 1994). The conclusion of this workshop was that, based on a type I error of 0.05 and a power of 80% to detect at least a doubling in the control frequency, the minimal number of cells to score per animal was 200 and the minimal number of animals to score per sex per treatment group was four.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Summary report of the Working Group on Mammalian Germ Cell Tests.

The two tests considered by the Working Group were the mammalian germ cell cytogenetic assay and the rodent dominant lethal test. It was agreed that both tests were mainly used for identification of germ cell hazards, however, that the commonly applied protocol of the dominant lethal assay often supplied information for hazard characterization such as sensitivity of particular developmental stages of male germ cells. No particular species or strains were indicated. Concurrent solvent controls were regarded as indispensable for both tests. In the discussion of the mammalian germ cell cytogenetic assay, harmonization was obtained to a large extent with the cytogenetic bone marrow assay regarding the number of animals (5), the number of cells analyzed per animal (200), the highest exposure dose (MTD) and sampling times (twice within 24 and 48 h after dosing). However, it was pointed out that only the single acute exposure was adequate for the mammalian germ cell cytogenetic assay. Furthermore, it was stated that only structural chromosome aberrations could be analyzed and that it was not informative to score polyploidies or aneuploidies. In the discussion of the rodent dominant lethal test, it was stated that the assay was generally performed with treated males, however, increasing concern about female specific effects required that a protocol for female dominant lethal testing should be developed and validated. Acute and subacute treatment schedules were considered equally acceptable. It was regarded as highly important that the entire male germ cell development from meiosis to mature sperm was covered in the test protocol either by the appropriate mating schedules after single dosing or by subchronic dosing during the respective period. Postimplantation loss, preimplantation loss and fertility rate were the main parameters to be assessed in the rodent dominant lethal tests. It was agreed that the size of the experiment depended on the spontaneous frequency of dead implants, the mating scheme and the statistical design of the experiment.

Aneuploidy↗
PubMed1994

In vivo rodent erythrocyte micronucleus assay.

The following summary represents a consensus of the working group except where noted. The items discussed are listed in the order in which they appear in the OECD guideline (474) for easy reference. Introduction, purpose, scope, relevance, application and limits of test. The analysis of immature erythrocytes in either bone marrow or peripheral blood is equally acceptable for those species in which the spleen does not remove micronucleated erythrocytes. In the mouse, mature erythrocytes are also an acceptable cell population for micronucleus analysis when the exposure duration exceeds 4 weeks. Test substances. Organic solvents such as DMSO are not recommended. Freshly prepared solutions or suspensions should be used unless stability data demonstrate the acceptability of storage. Vegetable oils are acceptable as solvents or vehicles. Suspension of the test chemicals is acceptable for p.o. or i.p. administration but not for i.v. injection. The use of any unusual solvent should be justified. Selection of species. Any commonly used laboratory rodent species is acceptable. There is no strain preference. Number and sex. The size of experiment (i.e., number of cells per animal, number of animals per group) should be finalized based on statistical considerations. Although a consensus was not achieved, operationally it was agreed that 2000 cells per animal and four animals per group was a minimum requirement. In general, the available database suggests that the use of one gender is adequate for screening. However, if there is evidence indicating a significant difference in the toxicity between male and female, then both sexes should be used. Treatment schedule. No unique treatment schedule can be recommended. Results from extended dose regimens are acceptable as long as positive. For negative studies, toxicity should be demonstrated or the limit dose should be used, and dosing continued until sampling. Dose levels. At least three dose levels separated by a factor between 2 and square root of 10 should be used. The highest dose tested should be the maximum tolerated dose based on mortality, bone marrow cell toxicity, or clinical symptoms of toxicity. The limit dose is 2 g/kg/day for treatment periods of 14 days or less and 1 g/kg/day for treatment periods greater than 14 days. A single dose level (the limit dose) is acceptable if there is no evidence of toxicity. Controls. Concurrent solvent (vehicle) controls should be included at all sampling times. A pretreatment sample, however, may also be acceptable only in the short treatment period peripheral blood studies. A concurrent positive control group should be included for each experiment.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

In vivo studies on chemically induced aneuploidy in mouse somatic and germinal cells.

Within the context of a coordinated program to study aneuploidy induction sponsored by the European Community, nine chemicals were tested in mouse bone marrow and spermatocytes after intraperitoneal injection. In somatic cells, cell progression delay, hyperploidy, polyploidy induction and induction of micronucleated polychromatic erythrocyte (MnPCE) were studied. In germ cells hyperploidy induction was evaluated. The chemicals selected were: colchicine (COL), econazole (EZ), hydroquinone (HQ), thiabendazole (TB), diazepam (DZ), chloral hydrate (CH), cadmium chloride (CD), pyrimethamine (PY) and thimerosal (TM). Using literature data on c-mitotic effects in bone marrow as a reference, the same doses were tested in somatic and germ cells in order to compare the effects induced. Bone marrow cells were sampled 18 or 24 h after treatment. Germ cells were sampled 6, 8 or 18 h after treatment. Effects of COL and HQ in bone marrow have been reported elsewhere. Somatic effects were induced by CH (hyperploidy and cell cycle lengthening), TB (MnPCEs and cell cycle lengthening) and by PY (MnPCEs). EZ, DZ, CD and TM did not induce any kind of somatic effects. An increase in the incidence of hyperploid spermatocytes was induced by COL, at three dose levels, and by one dose of HQ and TB. All the other chemicals did not induce germinal aneuploidy at any dose or time tested. The hyperploidy control frequency ranged between 0.4 and 1.0% in somatic cells and from 0.3 to 0.9% in germ cells. In both somatic and germ cells, the maximum yield of induced hyperploidy did not exceed 3.5%. The time period of target cell sensitivity is probably restricted and this, associated with the heterogeneity and the asynchrony of cellular maturation processes, may account for our data. Under these circumstances, the negative data should be interpreted with some caution, particularly in germ cells, where additional indicators of chemical-cell interaction and cell cycle effects were not provided by standardized approaches. The possibility of increasing the size of analyzed cell samples could be considered in the light of automatic scoring procedures.

Aneuploidy↗
PubMed1993

Noscapine does not show aneugenic activity in mouse oocytes.

To clarify if noscapine has the ability to induce polyploidy in rodent germ cells in vivo, a cytogenetic study of mouse metaphase II oocytes was conducted after oral treatment with noscapine at the doses of 20, 120 and 400 mg/kg. Plasma concentrations of noscapine were measured by reversed-phase liquid chromatography and UV detection in three satellite groups of mice up to 8 h after administration of these doses. Thus, the relationship of the maximum plasma concentration and the area under the curve (AUC) with that of meiotic progression could be established. Although noscapine was tested at the maximum tolerated dose, no delay of meiotic progression or induction of chromosome malsegregation could be shown as no increase in the frequency of metaphase I-arrested, polyploid or hyperploid oocytes were found. At the highest dose only, noscapine affected the physiology of superovulation as shown by a significant decrease in the mean number of oocytes harvested per female. In view of the large span covered by the doses tested, corresponding to concentrations far above those detected in humans, and the similarity between the pharmacokinetics of noscapine in mouse and humans, it is unlikely that noscapine represents a genetic risk for humans at therapeutic dosages.

Aneuploidy↗
PubMed1992

Griseofulvin-induced aneuploidy and meiotic delay in female mouse germ cells. I. Cytogenetic analysis of metaphase II oocytes.

Griseofulvin (GF) was tested in female mouse germ cells for the induction of aneuploidy and meiotic arrest. Superovulated mice were orally treated with 200, 666, 1332 or 2000 mg/kg in olive oil at the time of human chorionic gonadotrophin (HCG) injection and were sacrificed 18 h later. A dose-dependent increase in the frequency of metaphase I (M I) arrested oocytes was observed (maximum of 70%). Aneuploidy was not significantly induced. Also, the kinetics of meiotic progression up to the metaphase II (M II) stage was studied in untreated mice in order to correlate the time of treatment with the time of the first meiotic division. The results demonstrate that the majority of cells was treated with GF approximately 8 h before the M I stage. A second series of experiments were performed to test GF effects at a different treatment time. Doses of 200, 666 or 2000 mg/kg were administered 2 h post HCG. As in the first series of experiments, the animals were sacrificed 18 h post HCG. The results, compared with those obtained in the first experimental series, showed an inverse trend for meiotic arrest and aneuploidy induction. The frequency of M I arrested oocytes dropped from a maximum of 70% to a maximum of 20%, while, at the latest treatment time, a dose-dependent increase in the frequency of hyperploid oocytes was observed up to 56% aberrant cells at 2000 mg/kg. Altogether the results suggest that the arrest of meiotic division and the induction of aneuploidy by GF are caused by interaction with different targets or different developmental stages of the same target. In conclusion, GF has been shown to induce aneuploidy during the first meiotic division in a dose-related manner, together with other effects such as polyploidy, developmental delay and meiotic arrest. Also, these findings demonstrate that the sensitivity of the oocyte target(s) may be restricted to a specific time period and that a correct experimental protocol is critical for assessing the aneugenic activity of a chemical.

Aneuploidy↗
PubMed1992

Griseofulvin-induced aneuploidy and meiotic delay in female mouse germ cells. II. Cytogenetic analysis of one-cell zygotes.

The effects of griseofulvin (GF) upon the first meiotic division of female mouse germ cells were evaluated by cytogenetic analysis of first-cleavage (1-Cl) zygotes. The present study is an extension of an investigation that began with the cytogenetic analysis of metaphase II (M II) oocytes. Different doses (200, 666, 1332, 2000 mg/kg) were tested by oral administration of GF to superovulated animals either at the time of human chorionic gonadotrophin (HCG) injection or 2 h post HCG. When GF was given at the time of HCG, significant dose-dependent increases of different types of cytogenetically abnormal cells were found. These included zygotes containing ostensibly female-derived M I or M II arrested chromosomes and polyploid zygotes. The total yields of these aberrations were 2.9, 4.3, 26.2, 60.6, and 64.1% for control, 200, 666, 1332, and 2000 mg/kg, respectively. The origin of these zygotes was attributed to the fertilization of oocytes that had been previously arrested at M I. No significant induction of hyperploidy was detected. Developmentally abnormal zygotes were still observed when GF was administered 2 h post HCG, although their frequencies were significantly lower than in the first series of experiments. The yields of developmentally abnormal zygotes were 49, 10.2, and 23.6% at 200, 666, and 2000 mg/kg. Additionally, a dose-dependent increase in the frequency of hyperploid zygotes was detected up to a maximum of 36.5% at 2000 mg/kg. These results confirm the cytogenetic observations from M II oocytes after GF treatment under the same experimental conditions; namely, a dramatic change in the oocyte target susceptibility to GF occurred within a short time period. Also, the present study demonstrated that most of GF-induced aneuploid oocytes were fertilized and reached first-cleavage metaphase.

Aneuploidy↗
PubMed1991

Vinblastine-induced numerical chromosome changes and selection processes in mouse bone marrow cells.

The effect of selection processes operating on chemically induced aneuploid and polyploid cells was studied in mouse bone marrow cells at their third generation after a single i.p. treatment with vinblastine (VBL). Bromodeoxyuridine (BrdUrd)-labeled metaphases were analyzed for chromosome number and the frequencies of aneuploid and polyploid cells recorded at 2 different times, both within the third cell cycle after VBL treatment. Cell-cycle progression was analyzed for both control and treated mice at the 2 fixation times. Our data suggest that polyploid cells and possibly also cells with numerous additional chromosomes could have a cell cycle longer than that of diploid cells and cells hyperploid for 1-2 additional chromosomes. Both hyperploid and polyploid cells seem to have a reduced probability of undergoing further mitoses, as shown by the reduction of their frequencies at the third cell cycle, when compared to the frequencies observed in the second cell cycle after the same VBL treatment.

Aneuploidy↗
PubMed1991

Origin of aneuploidy in relation to disturbances of cell-cycle progression. II: Cytogenetic analysis of various parameters in mouse bone marrow cells after colchicine or hydroquinone treatment.

The relationship between in vivo aneuploidy and cell-cycle perturbation induced by potential aneugens was investigated in mouse bone marrow cells. This work was performed within the framework of a research programme coordinated by the European Community to study the ability of 10 selected chemicals to induce aneuploidy in different systems. In this context, the effects of colchicine (COL) and hydroquinone (HQ) on cell-cycle progression, aneuploidy, polyploidy, micronucleus and sister chromatid exchange induction in mouse bone marrow cells after bromodeoxyuridine incorporation are reported. Hyperploidy and polyploidy were scored in metaphases of cells that had undergone only one division after treatment. Both chemicals induced cell-cycle lengthening, hyperploidy and micronuclei. The kinetics of hyperploidy induction by the two compounds differed in that COL was positive at 24 h, whereas HQ was positive 18 h after treatment. Only colchicine was positive for polyploidy induction and neither chemical induced sister chromatid exchange. These results are compared with similar data obtained after vinblastine (VBL) treatment. The results suggest that VBL and COL induce chromosome malsegregation via a mechanism associated with perturbations in the cell-cycle, whereas HQ induces aneuploidy independently of cell-cycle lengthening, possibly altering a chromosomal component of chromosome segregation rather than a spindle component.

Aneuploidy↗
PubMed1990

Origin of aneuploidy in relation to disturbances of cell-cycle progression. I. Effects of vinblastine on mouse bone marrow cells.

Vinblastine (VBL) was tested in the mouse for induction of chromosome malsegregation in bone marrow cells. The occurrence of aneuploidy and polyploidy was correlated with cell-cycle kinetics measured by DNA labelling with bromodeoxyuridine (BrdUrd). Sister-chromatid exchanges (SCE) were also detected. A dose-dependent lengthening of the cell cycle was induced in the dose range of 0.9-4.5 mg/kg body weight, up to a complete inhibition of cell-cycle progression (100% of metaphases were arrested before completion of the first mitotic division following a recovery time of 18 h, compared with 8% in the controls). Both aneuploidy and polyploidy were induced. Aneuploid metaphases were grouped into 2 classes, those with no more than 2 extra chromosomes and those with 3-10 extra chromosomes. The frequencies of cells with severe aneuploidy and polyploidy increased considerably when second-generation cells were sampled at a recovery time of 24 h. This observation suggested that gross chromosome imbalances occur preferentially after a period of mitotic arrest, probably as a consequence of multipolar spindles or failure of proper spindle assembly. Non-disjunction of single chromosomes arises independently of the mitotic block. A slight increase in SCE frequency was observed only at a recovery time of 18 h. This study may provide information on the kinetics and mechanisms of origin of VBL-induced numerical aberrations in vivo.

Analysis of Variance↗
PubMed1989

Lack of induction of somatic aneuploidy in the mouse by nitrilotriacetic acid (NTA).

Nitrilotriacetic acid (NTA) was tested for the induction of aneuploidy in mouse bone marrow cells. Doses of 138 or 275 mg/kg of body weight were intraperitoneally injected 24 h after implantation of a bromodeoxyuridine tablet. Cell-replication kinetics was assessed by comparing the relative percentages of first, second and third metaphases in control and treated samples. The hyperploidy incidence was estimated in second metaphases only, together with the SCE/cell level. Mice injected with 1.8 mg/kg vinblastine (VBL) were used as positive controls. A slight delay of cell cycle was induced by NTA, as shown by regression analysis applied to average generation time values. No increase over the control level was observed for hyperploidy or SCE induction in NTA-treated mice. VBL induced both cell-cycle alteration and a highly significant (P less than 0.001) increase of the hyperploid cell frequency. On the basis of these and previous (Costa et al., 1988) observations it seems that the non-disjunctional activity of NTA in the mouse is confined to meiotic processes.

Acetates↗