Liver cells without Separase (right) become large and polyploid.
Work in flies and fission yeast has previously shown that cells lacking separase, an enzyme required to break the cohesive force that holds sister chromatids together through anaphase, exited mitosis despite having failed to separate chromosomes. The daughter cells in yeast carried broken chromosome and died as a result, whereas fly daughter cells had reduplicated chromosomes and were initially viable.
The two teams have now found that the same thing happens in mouse cells that lack separase. In the absence of separase activity, most of the cohesin dissipated as expected from chromosome arms, but the enzyme was required to remove the cohesive glue at the centromeres themselves.
Embryos lacking separase die...
