Chromosomes are not packed randomly in the nucleus. The Rabl orientation is an 
example of the non-random arrangement of chromosomes, centromeres are grouped in 
a limited area near the nuclear periphery and telomeres are located apart from 
centromeres. This orientation is established during mitosis and maintained 
through subsequent interphase in a range of species. We report that a Rabl-like 
configuration can be formed de novo without a preceding mitosis during the 
transition from the sexual phase to the vegetative phase of the life cycle in 
fission yeast. In this process, each of the dispersed centromeres is often 
associated with a novel Sad1-containing body that is contacting a cytoplasmic 
microtubule laterally (Sad1 is a component of the spindle pole body (SPB)). The 
Sad1-containing body was colocalized with other known SPB components, Kms1 and 
Spo15 but not with Cut12, indicating that it represents a novel SPB-related 
complex. The existence of the triplex structure (centromere-microtubule-Sad1 
body) suggests that the clustering of centromeres is controlled by a cytoplasmic 
microtubular system. Accordingly, when microtubules are destabilized, clustering 
is markedly reduced.