Spatial association of homologous pericentric regions in
human lymphocyte nuclei during repair
Shamci Monajembashi 1*, Alexander Rapp 1, Eberhard Schmitt 1, Heike Dittmar 1, Karl Otto Greulich 1 and Michael Hausmann 2
1 Institute of Molecular Biotechnology Jena
2 Institute of Pathology University Hospital Freiburg
* To whom correspondence should be addressed. E-mail: shamci{at}imb-jena.de.
Submitted on June 30, 2004
Revised on August 20, 2004
Accepted on 21 December 2004
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Abstract |
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Spatial positioning of pericentric chromosome regions in human lymphocyte cell nuclei was investigated during repair following H2O2/L-histidine treatment. 15 to 300 min after treatment these regions of chromosomes 1, 15, and X were labelled by fluorescence in situ hybridisation. The relative locus distances (LL-distances), the relative distances to the nuclear centre (LC-distances), and the locus-nuclear centre-locus angles (LCL-angles) were measured in approximately 5000 nuclei after 2D-microscopy. Experimental frequency histograms were compared to control-data from untreated stimulated and quiescent (G0) nuclei and to a theoretical 2D projection from random points. Based on the frequency distributions of the LL-distances and the LCL-angles an increase of closely associated labelled regions was found shortly after repair activation. For longer repair times this effect decreased. After 300 min the frequency distribution of the LL-distances was found to be compatible with the random distance distribution again. The LL-distance frequency histograms for quiescent nuclei did not significantly differ from the theoretical random distribution, although this was the case for the stimulated control of chromosomes 15 and X. It may be inferred that concerning the distances, homologous pericentric regions appear not to be randomly distributed during S-phase and are subjected to dynamic processes during replication and repair.
Key Words:
DNA repair, chromosome, chromosome territories, nuclear architecture, numeric simulation, oxidative stress
