THE NUCLEAR POSITION OF PERICENTROMERIC DNA OF CHROMOSOME-11 APPEARS TO BE RANDOM IN G(0) AND NONRANDOM IN G(1) HUMAN-LYMPHOCYTES

The nuclear topography of pericentromeric DNA of chromosome 11 was ana lyzed in G(0) (nonstimulated) and G(1) [phytohemagglutinin (PHA) stimu lated] human lymphocytes by confocal microscopy. In addition to the nu clear center, the centrosome was used as a second point of reference i n the three-dimensional (3D) analysis. Pericentromeric DNA of chromoso me 11 and the centrosome were labeled using a combination of fluoresce nt in situ hybridization (FISH) and immunofluorescence. To preserve th e 3D morphology of the cells, these techniques were performed on whole cells in suspension. Three-dimensional images of the cells were analy zed with a recently developed 3D software program (Interactive Measure ment of Axes and Positioning in 3 Dimensions). The distribution of the chromosome 11 centromeres appeared to be random during the G(0) stage but clearly non-random during the G(1) stage, when the nuclear center was used as a reference point. Further statistical analysis of the G( 1) cells revealed that the centromeres were randomly distributed in a shell underlying the nuclear membrane. A topographical relationship be tween the centrosome and the centromeres appeared to be absent during the G(0) and G(1) stages of the cell cycle.