The human chromosomal fragile sites more often involved in constitutional deletions and duplications – A genetic and statistical assessment

2016 ◽  
Author(s):  
Dora Prata Gomes ◽  
Inês J. Sequeira ◽  
Carlos Figueiredo ◽  
José Rueff ◽  
Aldina Brás
Keyword(s):  
Fragile Sites ◽  
Statistical Assessment ◽  
Chromosomal Fragile Sites

scholarly journals Chromosomal Instability at Fragile Sites in Blue Foxes, Silver Foxes, and Their Interspecific Hybrids

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1743
Author(s):  
Marta Kuchta-Gładysz ◽  
Ewa Wójcik ◽  
Anna Grzesiakowska ◽  
Katarzyna Rymuza ◽  
Olga Szeleszczuk
Keyword(s):  
Interspecific Hybrids ◽  
Genome Stability ◽  
Diploid Number ◽  
Fragile Sites ◽  
B Chromosomes ◽  
Silver Fox ◽  
Chromosomal Breaks ◽  
Blue Fox ◽  
Chromosomal Fragile Sites ◽  
Karyotypic Variation

A cytogenetic assay based on fragile sites (FS) enables the identification of breaks, chromatid gaps, and deletions. In healthy individuals, the number of these instabilities remains low. Genome stability in these species is affected by Robertsonian translocations in the karyotype of the blue fox and by B chromosomes in the silver fox. The aims of the study were to characterise the karyotype of blue foxes, silver foxes, and their hybrids and to identify chromosomal fragile sites used to evaluate genome stability. The diploid number of A chromosomes in blue foxes ranged from 48 to 50, while the number of B chromosomes in silver foxes varied from one to four, with a constant number of A chromosomes (2n = 34). In interspecific hybrids, both types of karyotypic variation were identified, with the diploid number of A chromosomes ranging from 40 to 44 and the number of B chromosomes varying from 0 to 3. The mean frequency of FS in foxes was 4.06 ± 0.19: 4.61 ± 0.37 in blue foxes, 3.46 ± 0.28 in silver foxes, and 4.12 ± 0.22 in hybrids. A relationship was identified between an increased number of A chromosomes in the karyotype of the hybrids and the frequency of chromosomal breaks. The FS assay was used as a biomarker for the evaluation of genomic stability in the animals in the study.

Cutis verticis gyrata and chromosomal fragile sites

1991 ◽  
Vol 38 (2-3) ◽  
pp. 249-250 ◽  
Author(s):  
S. A. Musumeci ◽  
R. Ferri ◽  
M. Viglianesi ◽  
M. Elia ◽  
R. M. Ragusa ◽  
...  
Keyword(s):  
Fragile Sites ◽  
Cutis Verticis Gyrata ◽  
Chromosomal Fragile Sites

scholarly journals Detours to Replication: Functions of Specialized DNA Polymerases during Oncogene-induced Replication Stress

2018 ◽  
Vol 19 (10) ◽  
pp. 3255 ◽  
Author(s):  
Wei-Chung Tsao ◽  
Kristin Eckert
Keyword(s):  
Dna Replication ◽  
Stress Responses ◽  
Dna Polymerases ◽  
Repetitive Sequences ◽  
Replication Stress ◽  
Fragile Sites ◽  
Cancer Development ◽  
Cycle Arrest ◽  
Chromosomal Fragile Sites ◽  
Dna Secondary Structures

Incomplete and low-fidelity genome duplication contribute to genomic instability and cancer development. Difficult-to-Replicate Sequences, or DiToRS, are natural impediments in the genome that require specialized DNA polymerases and repair pathways to complete and maintain faithful DNA synthesis. DiToRS include non B-DNA secondary structures formed by repetitive sequences, for example within chromosomal fragile sites and telomeres, which inhibit DNA replication under endogenous stress conditions. Oncogene activation alters DNA replication dynamics and creates oncogenic replication stress, resulting in persistent activation of the DNA damage and replication stress responses, cell cycle arrest, and cell death. The response to oncogenic replication stress is highly complex and must be tightly regulated to prevent mutations and tumorigenesis. In this review, we summarize types of known DiToRS and the experimental evidence supporting replication inhibition, with a focus on the specialized DNA polymerases utilized to cope with these obstacles. In addition, we discuss different causes of oncogenic replication stress and its impact on DiToRS stability. We highlight recent findings regarding the regulation of DNA polymerases during oncogenic replication stress and the implications for cancer development.

Genetics of Autism: Association of Chromosomal Fragile Sites

2001 ◽  
Vol 1 (4) ◽  
pp. 293-299 ◽  
Author(s):  
K.R. Manjunatha ◽  
G.K. Chetan ◽  
R. Arathi ◽  
S. Padma ◽  
H.N. Venkatesh ◽  
...  
Keyword(s):  
Fragile Sites ◽  
Chromosomal Fragile Sites

Chromosomal Fragile Sites: Molecular Test of the Delayed-replication Model

1993 ◽  
Vol 58 (0) ◽  
pp. 633-635 ◽  
Author(s):  
C.D. Laird ◽  
R.S. Hansen ◽  
T.K. Canfield ◽  
M.M. Lamb ◽  
S.M. Gartler
Keyword(s):  
Fragile Sites ◽  
Molecular Test ◽  
Chromosomal Fragile Sites ◽  
Replication Model

scholarly journals Over half of breakpoints in gene pairs involved in cancer-specific recurrent translocations are mapped to human chromosomal fragile sites

BMC Genomics ◽  
2009 ◽  
Vol 10 (1) ◽  
pp. 59 ◽  
Author(s):  
Allison A Burrow ◽  
Laura E Williams ◽  
Levi CT Pierce ◽  
Yuh-Hwa Wang
Keyword(s):  
Fragile Sites ◽  
Gene Pairs ◽  
Chromosomal Fragile Sites

scholarly journals Two mechanisms of chromosome fragility at replication-termination sites in bacteria

2021 ◽  
Vol 7 (25) ◽  
pp. eabe2846
Author(s):  
Qian Mei ◽  
Devon M. Fitzgerald ◽  
Jingjing Liu ◽  
Jun Xia ◽  
John P. Pribis ◽  
...  
Keyword(s):  
Replication Fork ◽  
Genome Instability ◽  
Neurological Diseases ◽  
Strand Break ◽  
Fragile Sites ◽  
Holliday Junctions ◽  
Dna Breaks ◽  
Dna Damage And Repair ◽  
Chromosome Fragility ◽  
Chromosomal Fragile Sites

Chromosomal fragile sites are implicated in promoting genome instability, which drives cancers and neurological diseases. Yet, the causes and mechanisms of chromosome fragility remain speculative. Here, we identify three spontaneous fragile sites in the Escherichia coli genome and define their DNA damage and repair intermediates at high resolution. We find that all three sites, all in the region of replication termination, display recurrent four-way DNA or Holliday junctions (HJs) and recurrent DNA breaks. Homology-directed double-strand break repair generates the recurrent HJs at all of these sites; however, distinct mechanisms of DNA breakage are implicated: replication fork collapse at natural replication barriers and, unexpectedly, frequent shearing of unsegregated sister chromosomes at cell division. We propose that mechanisms such as both of these may occur ubiquitously, including in humans, and may constitute some of the earliest events that underlie somatic cell mosaicism, cancers, and other diseases of genome instability.

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