Does Centromere Clustering at Interphase Reflect Anaphase Chromosome Orientation or Another Kind of Nuclear Organization?
We have studied centromere distribution in both intact and gently spread nuclei. Spreading was performed to improve the spatial resolution of nuclear structures. FISH with a pancentromeric probe showed that centromere clustering is a prominent feature of interphase nuclear architecture in rapidly dividing budding yeast cells. Centromere clusters generally occupied a small domain at the periphery of the nucleus, from which the chromosome arms projected. Recently, Guacci et al. (1997) had also inferred a cell cycle–dependent clustering of centromeres from the closer than random spatial association of the centromeres of three chromosomes. Whereas it is reasonable to assume that centromere clustering is a consequence of anaphase chromosome polarization, and thus an aspect of the Rabl-orientation, it would probably be randomized by Brownian motion if it was not fixed by the anchoring of chromatin to the nuclear matrix or the nuclear envelope (Marshall et al., 1997). In addition or alternati
