Evidence for a Relatively Random Array of Human Chromosomes on the Mitotic Ring

Abstract

We used fluorescence in situ hybridization (FISH) to study the positions of human chromosomes on the mitotic rings of cultured human lymphocytes, MRC-5 fibroblasts, and CCD-34Lu fibroblasts. The homologous chromosomes of all three cell types had relatively random positions with respect to each other on the mitotic rings of prometaphase rosettes and anaphase cells. Also, the positions of the X and Y chromosomes, colocalized with the somatic homologues in male cells, were highly variable from one mitotic ring to another. Although random chromosomal positions were found in different pairs of CCD-34Lu and MRC-5 late-anaphases, the separations between the same homologous chromosomes in paired late-anaphase and telophase chromosomal masses were highly correlated. Thus, although some loose spatial associations of chromosomes secondary to interphase positioning may exist on the mitotic rings of some cells, a fixed order of human chromosomes and/or a rigorous separation of homologous chromosomes on the mitotic ring are not necessary for normal mitosis. Furthermore, the relative chromosomal positions on each individual metaphase plate are most likely carried through anaphase into telophase.

Granulocytic nuclear differentiation of lamin B receptor–deficient mouse EPRO cells

“…We have speculated [32] that the ring-shape may be related to the frequently described "rosette" arrangement of chromosomes at the metaphase plate. [54,55] During mitosis in the bone marrow of normal mice, the telocentric heterochromatin should situate near the central "hub" of the mitotic "rosettes" and be pulled towards the polar centrioles. We suggest that post-mitotic nuclear reformation kinetics may be influenced by this central distribution of centromeric heterochromatin, which might associate with LBR to facilitate membrane growth in the vicinity of the centrosomes creating an annulus.…”

Parental genomes mix in mule and human cell nuclei

“…A precise antiparallel positioning of chromosome sets was claimed for the mitotic rosette and interphase nuclei, thus advocating a separation of haploid genomes (Nagele et al 1995(Nagele et al , 1998(Nagele et al , 1999. While an antiparallel order could not be confirmed by other groups (Allison and Nestor 1999;Cornforth et al 2002;Bolzer et al 2005;Mayer et al 2005), whether or not parental genomes are separated in another pattern remained unclear.…”

Chromosome architecture in the decondensing human sperm nucleus

“…An ordered, relative position of chromosomes remains controversial. Some studies observed fixed chromosome positioning in the prometaphase-metaphase ring (Leitch et al, 1994;Nagele et al, 1995), whereas another study did not establish such order (Allison and Nestor, 1999). In any case, it would be interesting to compare the relative positioning of chromosomes in sperm, prometaphase plate and pronuclei to explore the possibility of the ordered positioning inheritance.…”