Opening closed pores

A closed mitosis may be less closed than was thought, based on results from Colin De Souza, Stephen Osmani, and colleagues (The Ohio State University, Columbus, OH). The authors find that a fungus opens nuclear pores during mitosis to permit diffusion into and out of the nucleus. Simple organisms may thus be viable model systems for the study of nuclear changes during mammalian mitosis.

As the nuclear envelope is not broken down during a closed mitosis, the cell must regulate the nuclear entry of mitotic kinases and tubulin. This was assumed to occur through cell cycle regulated alterations of specific transport pathways. “I, and probably most everyone,” says Osmani, “almost took for granted that subtle changes in the transport properties of the pore alter import...