Search results for "ploidy"
showing 10 items of 299 documents
Aneuploidy as a consequence of senescence and ovariectomy in the golden hamster (Mesocricetus auratus).
1978
The hypothesis of the preferred X-chromosome loss in elder human females was reevaluated in the golden hamster: early castration of females proved that the increase of aneuploid cells is correlated with the loss of the ovaries. But here, and in old females, aneuploidy consisted of random loss of excess of chromosomes, in no case an X-chromosome.
USE OF IN VITRO TISSUE CULTURE IN PROPAGATION AND GENETIC IMPROVEMENT OF FRUIT TREES
2020
La coltura in vitro, applicata alla propagazione e miglioramento genetico della biodiversità vegetale, può rappresentare uno strumento efficace per affrontare i problemi attuali come i cambiamenti climatici, le nuove esigenze dei consumatori e indirettamente lo sviluppo delle aree rurali. Inoltre, può assumere un ruolo strategico nel miglioramento genetico e nella propagazione delle cultivar al fine di ottenere genotipi resistenti, con frutti migliori dal punto di vista organolettico e piante capaci di adattarsi ai cambiamenti climatici. Il miglioramento genetico attraverso i metodi convenzionale è limitato da molti fattori infatti, gli alberi da frutto sono caratterizzati da un lungo perio…
Karyological observations on Isoetes duriei Bory (Lycophyta, Isoetaceae) in Sicily
2001
The tumor suppressor p14ARF hampers proliferation of aneuploid cells induced by CENP-E partial depletion
The Spindle Assembly Checkpoint (SAC) is a cellular surveillance mechanism that ensures faithfully segregation of chromosomes. Reduced expression of some of its components weakens the SAC and induces chromosome instability and aneuploidy, both hallmarks of tumor cells. Centromere Protein-E (CENP-E) is a crucial component of the SAC and facilitates kinetochore microtubule attachment required to achieve and maintain chromosome alignment. To investigate the possible role of p14ARF on aneuploid cells proliferation we induced aneuploidy in primary human fibroblasts (IMR90) and in near diploid tumor cells (HCT116) by partial depletion of CENP-E obtained by RNA interference. Our results show that …
Bypass of G1 arrest induced by DNMT1 posttranscriptional silencing triggers aneuploidy in human cells.
2010
Aneuploidy is a major source of genomic instability in cancer, resulting from chromosome segregation errors caused by defects in genes controlling correct mitotic spindle assembly, centrosome duplication and cell cycle checkpoints. Interestingly in aneuploid cells some of these genes, although not mutated, were underexpressed suggesting the involvement of epigenetic alterations. DNA methylation and histone modifications are the main epigenetic modifications occurring in cells. DNA methyl-transferase 1 (Dnmt1) is known to restore DNA methylation patterns during cell divisions. We investigated the effects of DNMT1 silencing by RNA-interference on the generation of aneuploidy in primary human …
Identification of pathways involved in aneuploidy onset and its tolerance using a DNA microarray approach
2013
Genomic instability is a hallmark of the majority of human tumors explaining the heterogeneity shown by tumor cells. This phenomenon is often associated with chromosomal instability (CIN) and aneuploidy, a condition in which tumor cells lose or gain chromosomes. Previously, we showed that posttranscriptional silencing by RNAi of pRb1, DNMT12 and MAD2 is associated with aneuploidy in cultured human cells reinforcing the idea that there are several roads leading to aneuploidy. In the attempt to understand if a common molecular signature exists underlying aneuploidy and its tolerance in tumor cells, we induced aneuploidy in human fibroblasts (IMR90) by depleting Rb, MAD2 and DNMT1 genes and an…
MECHANISMS OF CHROMOSOMAL INSTABILITY: RELATIONSHIP BETWEEN TUMOR SUPPRESSORS AND SAC GENES
2017
Caratteristica comune di molti tumori solidi è l’aneuploidia, conseguenza dell’instabilità cromosomica (CIN). Tuttavia non sono ancora chiari i meccanismi alla base dell’aneuploidia e i percorsi che permettono la sua tolleranza. Lo Spindle Assembly Checkpoint (SAC) è un meccanismo di sorveglianza cellulare che controlla la stabilità genomica durante la mitosi. Alterazioni nei membri del SAC generano aneuploidia, ma non è ancora chiaro se questi difetti sono sufficienti per promuovere la tumori-genesi. In questo processo, infatti, il contesto genetico della cellula gioca un ruolo importante. È risaputo che i difetti di p53 aiutano le cellule a proliferare velocemente tollerando la CIN. Al co…
Global DNA Hypomethylation following 5-aza-2'-deoxycytidine treatment induces aneuploidy in HCT-116 tumor cells.
2013
Aneuploidy, the alteration of the normal number of chromosomes, is found in most of the human solid tumors and correlated with to defects in the process of chromosome segregation (1). It was also suggested that the alteration of the 5-methylcytosine (5-mC) pattern in the chromosome pericentromeric region, generated to aneuploid cells (2, 3). To investigate the relationship between hypomethylation and whole chromosome aneuploidy, we treated HCT-116 cells, a near diploid line, with the demethylating agent 5-aza- 2'-deoxycytidine (DAC). The treatment with DAC for 24, 48 and 72 hours produced a progressive reduction of DNA methylation as shown by decrease of 5-mC signal. DNA hypomethylation res…
DNA Methyltransferase1 post-transcriptional silencing induces aneuploidy and cell cycle arrest in human cells.
2009
The regulation of chromatin structure is a dynamic and complex process that is modulated by epigenetic mechanisms. Malfunctioning of these processes can cause gene expression alteration and could compromise important events such as chromosome condensation and segregation. Imbalance in cytosine methylation and deregulation of DNA-methyltransferases (DNMTs), and of DNMT1 in particular, is frequent in human cancers. To investigate DNMT1 implication in the generation of aneuploidy we evaluated the effects of its depletion by RNA-interference both in primary human cells (IMR90) and in near diploid human tumor (HCT116) cells. Posttranscriptional silencing of DNMT1 induced aneuploidy, cell prolife…