Very excited that this collaboration with Sara Cuylen-Haering, Mina Petrovic et al is out in @nature today! 1/n Ever wonder why stuff from the cytoplasm doesn't mix into the nucleoplasm at every ridiculous open mitosis that our weirdo cells do? https://www.nature.com/articles/s41586-020-2672-3

2/n Things that are small enough can be pumped out through nuclear pores, but what about large particles like assembled ribosomes? Turns out that mitotic chromatin is so condensed that it excludes 40 nm particles (GEMs) and ribosomes. That Ki67 mitosis marker everyone uses...

3/n Ki67 was previously shown (by the same Daniel Gerlich team) to act as a surfactant to individualize chromosomes, but at mitotic exit, it changes into a glue and causes chromosomes to all cluster together. This clustering squeezes all those pesky cytoplasmics particles out...

4/n ...and then the nuclear envelope reforms right around the chromosome cluster restablishing the separate nucleoplasm. If clustering is disrupted, you wind up with ribosomes in the nucleus after division and the cells look real sad...

5/5 Presumably this is very important to prevent ribosomes from translating unprocessed RNA etc. This project started as some simple observations and conversations at @MBLScience and Daniel's group crushed it from there. Sara has her own group now at EMBL: https://bit.ly/31T43W5