Topography of telomeres and structure of chromosome territoriesin human lymphocytes

Nuclear and territorial positioning of p- and q- telomeres and centromeres of chromosomes 3, 8, 9, 13 and 19 were studied by repeated FISH, high-resolution cytometry and three-dimensional image analysis in human blood lymphocytes before and after stimulation. Telomeres were found on the opposite side of the territories as compared with the centromeres for all chromosome territories investigated. Mutual distances between telomeres of submetacentric chromosomes were very short, usually shorter than centromere-to-telomere distances, which means that the chromosome territory is non-randomly folded. Telomeres are in average much nearer to the center of the cell nucleus than centromeres; q-telomeres were found in average more centrally localized as compared with p-telomeres. Consequently, we directly showed that chromosome territories in the cell nucleus are (i) polar and (ii) partially oriented in cell nuclei. The distributions of genetic elements relative to chromosome territories (territorial distributions) can be either narrower or broader than their nuclear distributions, which reflects the degree of adhesion of an element to the territory or to the nucleus.