PRECISE SPATIAL POSITIONING OF CHROMOSOMES DURING PROMETAPHASE - EVIDENCE FOR CHROMOSOMAL ORDER

The relative locations of several chromosomes within wheel-shaped prom etaphase chromosome rosettes of human fibroblasts and HeLa cells were determined with fluorescence hybridization. Homologs were consistently positioned on opposite sides of the rosette, which suggests that chro mosomes are separated into two haploid sets, each derived from one par ent. The relative locations of chromosomes on the rosette were mapped by dual hybridizations. The data suggest that the chromosome orders wi thin the two haploid sets are antiparallel. This chromosome arrangemen t in human cells appears to be both independent of cell type- and spec ies-specific and may influence chromosome topology throughout the cell cycle.