The nuclear position of pericentromeric DNA of chromosome 11 appears to be random in GO and non-random in G1 human lymphocytes

The nuclear topography of pericentromeric DNA of chromosome 11 was analyzed in G₀ (nonstimulated) and G₁ phytohemagglutinin (PHA) stimulated] human lymphocytes by confocal microscopy. In addition to the nuclear center, the centrosome was used as a second point of reference in the three-dimensional (3D) analysis. Pericentromeric DNA of chromosome 11 and the centrosome were labeled using a combination of fluorescent in situ hybridization (FISH) and immunofluorescence. To preserve the 3D morphology of the cells, these techniques were performed on whole cells in suspension. Three-dimensional images of the cells were analyzed with a recently developed 3D software program (Interactive Measurement of Axes and Positioning in 3 Dimensions). The distribution of the chromosome 11 centromeres appeared to be random during the G₀ stage but clearly non-random during the G₁ stage, when the nuclear center was used as a reference point. Further statistical analysis of the G₁ cells revealed that the centromeres were randomly distributed in a shell underlying the nuclear membrane. A topographical relationship between the centrosome and the centromeres appeared to be absent during the G₀ and G₁ stages of the cell cycle.