Does S. pombe exploit the intrinsic asymmetry of DNA synthesis to imprint daughter cells for mating-type switching?

Typically cell division is envisaged to be symmetrical, with both daughter cells being identical. However, during development and cellular differentiation, asymmetrical cell divisions have a crucial role. In this article, we describe a model of how Schizosaccharomyces pombe exploits the intrinsic asymmetry of DNA replication machinery-the difference between the replication of the leading strand and the lagging strand-to establish an asymmetrical mating-type switching pattern. This is the first system where the direction of DNA replication is involved in the formation of differentiated chromosomes. The discovery raises the possibility that DNA replication might be more generally involved in the establishment of asymmetric cellular differentiation.