Excogitations About the Quantification of Structural Chromosomal Aberrations

On the nature of visible chromosomal gaps and breaks

“…Given changing sensitivity with development, the observed aberration yield is determined by the mixture of cell positions present in the sample. Since mitotic delay and perturbation are dose dependent, it is obvious that different cell mixtures will be present for different doses at the same fixation time, which negates legitimate yield comparisons (Savage and Papworth, 1991).…”

Effect of hypothermia on radiation-induced micronuclei and delay of cell cycle progression in TK6 cells

“…Moreover, we could show that its expression is transient in that the reduced level of MN was not seen in all samples of cells harvested sequentially after radiation exposure at low temperature (Dang et al 2012). Th e method of sequential harvesting, also known as the multiple fi xation regimen, was recommended to obtain a meaningful frequency of chromosomal aberrations in cells irradiated during asynchronous growth (Kaufman et al 1974, Savage andPapworth 1991). Th e underlying principle of this method is that it allows identifying increased or reduced levels of cytogenetic damage as being caused by transient shifts of the cell cycle if they are not observed in all samples harvested sequentially (Wojcik et al 1996).…”

Micronuclei: pitfalls and problems

“…Consequently, since the rate of generation and of dilution are both affected by kinetic factors (see below), neither the peak frequency, nor the integrated area under the yield time curve, are reliable measures of damage. This is a problem all too familiar to those who attempt quantitative work with chromatidtype aberrations (Savage and Papworth, 1991). b) Mitotic delay and perturbation.…”

“…Quite likely, the yield-time curve will have extra peaks and troughs and will not reflect the true sensitivity situation within the population. We always have to remember that the observed frequency of any event, with which we construct our graphs, and from which we draw our inferences, depends entirely upon the mixture of cells which is present in the sample scored (Savage and Papworth, 1991). Changes in this cell mixture can produce effects as profound as real treatment-induced changes.…”