6th ESACP Congress, Heidelberg, April 7-11, 1999

A086
THE ROLE OF THE DISTRIBUTIONS OF CHROMOSOME DOMAINS IN CELL NUCLEI IN THE INDUCTION OF TRANSLOCATIONS BY IONIZINIG RADIATION AND IN THE PATHOGENESIS OF LEUKEMIAS AND LYMPHOMAS
Kozubek S, Lukasova E, Skalnikova M, Kozubek M, Bartova E, Jirsova P, Cafourkova A, Koutna I

Institute of Biophysics, Academy of Sciences, Brno and Faculty of Informatics, Masaryk University, Brno, Czech Republic

The neighborhood relationships of chromosomes can be of great importance for basic cellular processes such as gene expression or translocation induction. In this study, the topological organization of chromosome domains was investigated in cell nuclei of human blood cells (mostly in Go-lymphocytes). We found that the domains were predominantly located in particular regions of cell nuclei. In addition to this, the domains can be probably associated in pairs. Both effects might substantially increase the probability of interaction between chromosomes. Because of this, exchange aberrations were studied in different chromosome pairs in human lymphocytes irradiated by neutrons. The rate of aberration induction between these chromosomes was compared with the expected frequency based on the fractional molecular weight of the chromosomes. An attempt was made to explain the increased rate of exchanges between some chromosome pairs using the topological parameters of the chromosomes. Similar topological characteristics of several genes were found in various human blood cell types: T- and B-lymphocytes, HL60 cells and bone-marrow cells. This finding suggests that the specific chromatin structure which is responsible for the increased frequency of the induction of translocations by ionizing radiation might be also responsible for the high rate of the induction of leukemias and lymphomas in the human population.