The Kinetics of Postirradiation Chromatin Restitution as Revealed by Chromosome Aberrations Detected by Premature Chromosome Condensation and FluorescenceIn SituHybridization

Abstract

In a study of X-ray-induced chromosome aberrations in human G(0) lymphocytes irradiated with 4 Gy using premature chromosome condensation (PCC) and fluorescence in situ hybridization (FISH), the time-dependent pattern of chromosome fragments and interchromosomal exchanges involving chromosome 4 was recorded after postirradiation incubation times varying from 0.5 to 46.5 h. Unattached acentric fragments and incomplete interchromosomal exchanges have high initial yields, followed by an exponential decrease, while complete interchromosomal exchanges have almost zero initial yield with a subsequent increase in their number. Plateau values of all yields are reached after about 25 h. This temporal variation of aberration yields can consistently be explained by the competition of disruptive PCC stress with the progress of postirradiation structural restitution at the sites of radiation-induced chromatin instabilities. Details of the temporal pattern of incomplete exchanges reflect the different kinetics of the alpha and beta components of the yield of aberrations. The observed large difference between late-PCC and metaphase yields of unattached acentric fragments and the almost perfect conversion from incomplete prematurely condensed chromosomes into complete metaphase exchanges are explained by a difference in the magnitude of chromosome condensation stress between PCC and mitotic conditions. Chromatin sites prone to fragmentation and incompleteness under conditions of PCC can therefore persist as genetic instabilities hidden during mitosis.

Development and characterisation of an irradiation device for biomedical studies covering the solar spectrum with individual regulated spectral bands

“…Experimental evaluations of the exposure of humans and cultured cell lines to solar radiation have been undertaken for many years. These studies were either performed using individual spectral regions in the UVB or UVA range [2][3][4][5][6] or solar spectrum simulator radiation (SSR) devices were used [7,8]. The majority of studies using SSR is based on xenon lamps combined with spectral filters to adapt the emission to the solar reference spectrum (air mass filters) [9][10][11].…”

Assessing the Applicability of FISH-based Prematurely Condensed Dicentric Chromosome Assay in Triage Biodosimetry

“…The yield of fragments decreased in a time-dependent manner (Darroudi et al 1998a). The dose response relationship for prematurely condensed dicentric chromosomes (PCDCs) was similar to that for metaphase dicentric chromosomes (Vyas et al 1991;Darroudi et al 1998a;Greinert et al 2000;IAEA 2011). The dose response relationship for prematurely condensed dicentric chromosomes (PCDCs) was similar to that for metaphase dicentric chromosomes (Vyas et al 1991;Darroudi et al 1998a;Greinert et al 2000;IAEA 2011).…”

Computer analysis of mFISH chromosome aberration data uncovers an excess of very complicated metaphases

“…It has quanti ed reasonable agreement of the BR model have a limited range (Kellerer and Rossi 1978). They in uence observed aberration spectra (see Sachs et al ( gure 1A) with the data (Sachs et al 2000c), but some discrepancies have been found, including an 2000a, Ottolenghi et al 2001) because chromosomes Computer analysis of mFISH chromosome aberration under-prediction of the frequency of the most with such early instability (Greinert et al 2000, Sipi et al 2000. This study will consider the possibility complex aberrations (Sachs et al 2000b).…”