Chromosome-specific nonrandom sister chromatid segregation during stem-cell division

Using a CO-FISH method with single-chromosome resolution, sister chromatids of the sex chromosomes, but not autosomes, are shown to segregate nonrandomly during asymmetric cell divisions of Drosophila male germline stem cells; this suggests that it is unlikely that nonrandom sister chromatid segregation serves to protect the ‘immortal strand’ to avoid replication-induced mutations as proposed previously.