Relationship between radiation-induced aberrations in individual chromosomes and their DNA content: effects of interaction distance.
OBJECTIVE
To study the effect of the interaction distance on the frequency of inter- and intrachromosome exchanges in individual chromosomes with respect to their DNA content. Assumptions: Chromosome exchanges are formed by misrejoining of two DNA double-strand breaks (DSB) induced within an interaction distance, d. It is assumed that chromosomes in G(0)/G(1) phase of the cell cycle occupy a spherical domain in a cell nucleus, with no spatial overlap between individual chromosome domains.


RESULTS
Formulae are derived for the probability of formation of inter-, as well as intra-, chromosome exchanges relating to the DNA content of the chromosome for a given interaction distance. For interaction distances <1 microm, the relative frequency of interchromosome exchanges predicted by the present model is similar to that by Cigarran et al. (1998) based on the assumption that the probability of interchromosome exchanges is proportional to the "surface area" of the chromosome territory. The "surface area" assumption is shown to be a limiting case of d-->0 in the present model. The present model also predicts that the probability of intrachromosome exchanges occurring in individual chromosomes is proportional to their DNA content with correction terms.


CONCLUSIONS
When the interaction distance is small, the "surface area" distribution for chromosome participation in interchromosome exchanges has been expected. However, the present model shows that for the interaction distance as large as 1 microm, the predicted probability of interchromosome exchange formation is still close to the surface area distribution. Therefore, this distribution does not necessarily rule out the formation of complex chromosomal aberrations by long-range misrejoining of DSB.
Wu
H
H
Radiation Biophysics Laboratory and Kelsey-Seybold Clinic, NASA Johnson Space Center, Mail Code SD23, Houston, TX 77058, USA. hwu@ems.jsc.nasa.gov
Durante
M
M
Lucas
J N
JN
D002869:Chromosome Aberrations; D002875:Chromosomes / Q000528:radiation effects* / Q000648:ultrastructure*; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage / Q000528:radiation effects*; D006801:Humans; D008962:Models, Theoretical; D011336:Probability
D004247:DNA