Xu et al. investigate how the speed of chromosome separation is regulated during the cleavage divisions of the Drosophila blastoderm. They find that spindle length and the cell cycle oscillator jointly control the velocity of chromosome movement in anaphase.

Despite tubulin’s evolutionary conservation, microtubule dynamics are highly temperature sensitive. Troman et al. use natural tubulin variants from closely related Xenopus species to show that a decrease in tubulin’s apparent activation energy and weakening of lateral lattice contacts stabilize microtubules in cold-adapted frogs.