Nucleolus organizer regions in human lymphocytes as studied with premature chromosome condensation

1990 ◽  
Vol 84 (3) ◽  
Author(s):  
Franz Wachtler ◽  
Christa Roubicek ◽  
Andreas Schedle ◽  
Wilhelm Mosg�ller ◽  
Gerlinde Bretis ◽  
...  
Keyword(s):  
Human Lymphocytes ◽  
Chromosome Condensation ◽  
Nucleolus Organizer ◽  
Premature Chromosome Condensation ◽  
Nucleolus Organizer Regions

scholarly journals Refined premature chromosome condensation (G0-PCC) with cryo-preserved mitotic cells for rapid radiation biodosimetry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Usha Yadav ◽  
Nagesh N. Bhat ◽  
Kapil B. Shirsaath ◽  
Utkarsha S. Mungse ◽  
Balvinder K. Sapra
Keyword(s):  
Mitotic Index ◽  
Human Lymphocytes ◽  
Mitotic Cell ◽  
Chromosome Condensation ◽  
Blood Collection ◽  
High Dose ◽  
Premature Chromosome Condensation ◽  
Isolated Cells ◽  
Emergency Scenarios ◽  
Mitotic Cells

AbstractMitotic cell fusion induced Premature Chromosome Condensation (G0-PCC) assay in human lymphocytes allows rapid detection of cytogenetic damage in interphase stage, within few hours after blood collection. Hence, it is the most suitable method for rapid and high dose biodosimetry. Mitotic cells, used for G0-PCC could be either freshly isolated or previously cryo-preserved. However, under emergency scenarios, only cryo-preserved cells can be relied upon, fresh isolation will only delay the process by 18–24 h. Impact of cryopreservation on mitotic cells and their efficacy to induce PCC are not reported. In the present study, we investigated effect of cryopreservation on mitotic cells and refined the parameters for G0-PCC. More than 95% of the cells were recoverable after 4 months of cryopreservation, within 20 min recovery at 37 °C, without significant change in the mitotic index or viability. Recovered mitotic cells have shown mitotic index of 89 ± 4% and viability of 90 ± 4%, similar to that of freshly isolated cells. Decrease in metaphases was observed within 40 min after recovery as the mitotic cells progressed through cell cycle and reduced to 21% at 1.5 h. Nevertheless, in presence of Colcemid, the cells progressed slowly and considerably high metaphase index (60%) persisted up to ~ 2 h. The recovered cells efficiently fused with lymphocytes and induced PCC. Average PCC index varied from 10 to 20%, which did not change with cryopreservation duration. Post fusion incubation duration of 2 h was found to be optimum for proper chromosome condensation. In conclusion, use of cryo-preserved mitotic cells is the most practical approach for rapid biodosimetry. The cells can be recovered quickly and efficiently without alteration in viability or mitotic index. Recovered cells are fully competent to induce G0-PCC.

scholarly journals Interphase Cytogenetic Analysis of Micronucleated and Multinucleated Cells Supports the Premature Chromosome Condensation Hypothesis as the Mechanistic Origin of Chromothripsis

Cancers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1123 ◽  
Author(s):  
Pantelias ◽  
Karachristou ◽  
Georgakilas ◽  
Terzoudi
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cytogenetic Analysis ◽  
Alternative Hypothesis ◽  
Chromatin Condensation ◽  
Human Lymphocytes ◽  
Chinese Hamster ◽  
Chromosome Condensation ◽  
Premature Chromosome Condensation ◽  
Multinucleated Cells

The discovery of chromothripsis in cancer genomes challenges the long-standing concept of carcinogenesis as the result of progressive genetic events. Despite recent advances in describing chromothripsis, its mechanistic origin remains elusive. The prevailing conception is that it arises from a massive accumulation of fragmented DNA inside micronuclei (MN), whose defective nuclear envelope ruptures or leads to aberrant DNA replication, before main nuclei enter mitosis. An alternative hypothesis is that the premature chromosome condensation (PCC) dynamics in asynchronous micronucleated cells underlie chromosome shattering in a single catastrophic event, a hallmark of chromothripsis. Specifically, when main nuclei enter mitosis, premature chromatin condensation provokes the shattering of chromosomes entrapped inside MN, if they are still undergoing DNA replication. To test this hypothesis, the agent RO-3306, a selective ATP-competitive inhibitor of CDK1 that promotes cell cycle arrest at the G2/M boundary, was used in this study to control the degree of cell cycle asynchrony between main nuclei and MN. By delaying the entrance of main nuclei into mitosis, additional time was allowed for the completion of DNA replication and duplication of chromosomes inside MN. We performed interphase cytogenetic analysis using asynchronous micronucleated cells generated by exposure of human lymphocytes to γ-rays, and heterophasic multinucleated Chinese hamster ovary (CHO) cells generated by cell fusion procedures. Our results demonstrate that the PCC dynamics during asynchronous mitosis in micronucleated or multinucleated cells are an important determinant of chromosome shattering and may underlie the mechanistic origin of chromothripsis.

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