Francesca Degrassi

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In mitotic cells, an error in chromosome segregation occurs when a chromosome is left near the spindle equator after anaphase onset (lagging chromosome). In PtK1 cells, we found 1.16% of untreated anaphase cells exhibiting lagging chromosomes at the spindle equator, and this percentage was enhanced to 17.55% after a mitotic block with 2 microM nocodazole. A(More)
We have characterized a nuclease hypersensitive chromatin fraction from murine spermatozoa. Endogenous nuclease activity can be induced in mouse epididymal spermatozoa by appropriate stimuli and cause the localized degradation of chromosomal DNA. Based on these observations, we have isolated nuclease hypersensitive chromatin regions released from(More)
Posttranslational modifications of core histones contribute to driving changes in chromatin conformation and compaction. Herein, we investigated the role of histone deacetylation on the mitotic process by inhibiting histone deacetylases shortly before mitosis in human primary fibroblasts. Cells entering mitosis with hyperacetylated histones displayed(More)
Centrosomes are the major sites for microtubule nucleation in mammalian cells, although both chromatin- and kinetochore-mediated microtubule nucleation have been observed during spindle assembly. As yet, it is still unclear whether these pathways are coregulated, and the molecular requirements for microtubule nucleation at kinetochore are not fully(More)
Workers in the petroleum distribution trades experience relatively high-level exposures to fuel vapours whose consequences have not been fully elucidated. In this study, the possible relationship between occupational exposure to petroleum fuels and cytogenetic damages in peripheral lymphocytes was investigated. Twenty-three male, non-smoking workers from(More)
The aim of the present work was to investigate the possible interference of cytochalasin B (cyt B) with low concentration treatment with colchicine in the induction of chromosome/chromatid loss and micronuclei in human lymphocytes mitotically activated in vitro. Thus, cells from a single female donor were treated with colchicine (10 or 25 nM, from 24 h(More)
In this work we have applied in situ hybridization with alphoid centromeric probes specific to chromosomes 7 and 11 to ana-telophase cells from human primary fibroblasts. The aim was to visualize the events leading to aneuploidy directly during anaphase, analyse the induction of aneuploidy during this mitotic stage and compare the frequencies of chromosome(More)
The immunofluorescent staining of kinetochores in micronuclei with antikinetochore antibodies was used to develop an in vitro assay for aneuploidy-inducing agents. The results show that about 80% of micronuclei induced by either colchicine or chloral hydrate contained kinetochores; only 9% of X-ray-induced micronuclei reacted positively to the antibody.(More)
The influence of sampling time on the frequencies of micronuclei, centromere-positive micronuclei and chromosome nondisjunction was investigated in binucleated lymphocytes following treatment with a known clastogen (mitomycin C) or an aneuploidy-inducing agent (vincristine sulfate). Cytochalasin B (6 micrograms/ml) was added 44 h after mitogen stimulation(More)
In the framework of the coordinated programme 'Genomic Mutations' sponsored by the Commission of European Communities, eight known or suspected spindle poisons (cadmium chloride, chloral hydrate, colchicine, diazepam, econazole, hydroquinone, pyrimethamine, thiabendazole, thimerosal and vinblastine) were tested in a modified in vitro micronucleus test in(More)