Chromosome Research

, Volume 21, Issue 3, pp 243-254

Nonrandom sister chromatid segregation of sex chromosomes in Drosophila male germline stem cells

  • Yukiko M. YamashitaAffiliated withLife Sciences Institute, Center for Stem Cell Biology, Department of Cell and Developmental Biology, School of Medicine, Cellular and Molecular Biology Program, University of Michigan Email author 


Sister chromatids are the product of DNA replication, which is assumed to be a very precise process. Therefore, sister chromatids should be exact copies of each other. However, reports have indicated that sister chromatids are segregated nonrandomly during cell division, suggesting that sister chromatids are not the same, although their DNA sequences are the same. Researchers have speculated that stem cells may retain template strands to avoid replication-induced mutations. An alternative proposal is that cells may segregate distinct epigenetic information carried on sister chromatids. Recently, we found that Drosophila male germline stem cells segregate sister chromatids of X and Y chromosomes with a strong bias. We discuss this finding in relation to existing models for nonrandom sister chromatid segregation.


stem cells sex chromosome asymmetric division