BiasedDNASegregation

Abstract

Biased chromatid segregation refers to the nonrandom distribution of chromatids in mitotic cells so that specific daughters inherit specific chromosomes or deoxyribonucleic acid (DNA) strands. This unusual behaviour has been documented primarily in the context of differentiation, when one cell divides to produce two daughter cells with distinct fates. When cells divide asymmetrically to produce such daughters, it has been noted that the DNA in these different daughter cells is dissimilar. Two controversial hypotheses to account for such data have been envisioned thus far: one in which stem cells retain all chromosomes carrying ancestral DNA strands, and one in which precursors segregate one or more, epigenetically dissimilar, strands nonrandomly. Several cases of biased DNA segregation are presented, and the implications of this theory are discussed with a view to general biological issues, the proximate mechanisms underlying these phenomena and the ultimate reasons these might occur. Key Concepts: The biased segregation of DNA might function to specify the fate of cells. It has been proposed that biased DNA segregation reduces DNA mutation load in the cell that retains ancestral, or original, DNA strands. Stem cell self‐renewal and multipotency, which are accounted for by asymmetric cell division, are also proposed to be an outcome of biased DNA segregation.