We describe a 28 year old male with a pseudodicentric Y chromosome who suffered from azoospermia attributed to maturation arrest of the primary spermatocyte, as diagnosed by testicular biopsy. Chromosome analysis, using G, Q and C banding techniques, revealed an abnormal karyotype of 45,X[7]/46,X,psu dic (Y)(pter-->q11.2::q11.2-->pter)[33]. Polymerase chain reaction (PCR) DNA analysis did not d...

Dicentric chromosomes have been identified as instigators of the genome instability associated with cancer, but this instability is often resolved by one of a number of different secondary events. These include centromere inactivation, inversion, and intercentromeric deletion. Deletion or excision of one of the centromeres may be a significant occurrence in myeloid malignancy and other malignan...

Activation of a facultative, dicentric chromosome provides a unique opportunity to introduce a double strand DNA break into a chromosome at mitosis. Time lapse video enhanced-differential interference contrast analysis of the cellular response upon dicentric activation reveals that the majority of cells initiates anaphase B, characterized by pole-pole separation, and pauses in mid-anaphase for ...

PURPOSE To evaluate the importance of annual intercomparisons for maintaining the capacity and capabilities of a well-established biodosimetry network in conjunction with assessing efficient and effective analysis methods for emergency response. MATERIALS AND METHODS Annual intercomparisons were conducted between laboratories in the Canadian National Biological Dosimetry Response Plan. Interc...

When a dicentric chromosome breaks in mitosis, the broken ends cannot be repaired by normal mechanisms that join two broken ends since each end is in a separate daughter cell. However, in the male germline of Drosophila melanogaster, a broken end may be healed by de novo telomere addition. We find that Chk2 (encoded by lok) and P53, major mediators of the DNA damage response, have strong and op...

Checkpoint mechanisms that respond to DNA damage in the mitotic cell cycle are necessary to maintain the fidelity of chromosome transmission. These mechanisms must be able to distinguish the normal telomeres of linear chromosomes from double-strand break damage. However, on several occasions, Drosophila chromosomes that lack their normal telomeric DNA have been recovered, raising the issue of w...

Gene amplification plays important roles in the progression of cancer and contributes to acquired drug resistance during treatment. Amplification can initiate via dicentric palindromic chromosome production and subsequent breakage-fusion-bridge cycles. Here we show that, in fission yeast, acentric and dicentric palindromic chromosomes form by homologous recombination protein-dependent fusion of...