Tension gets chromosomes oriented

During cell division pairs of chromosomes are pulled apart into the two newly forming cells. Before this can occur, kinetochores are repeatedly connected to and disconnected from microtubules until paired kinetochores are attached to opposite poles and the chromosomes are said to be bioriented. The first suggestion of how cells discard the wrong configurations, such as when both members of a chromosome pair are attached to the same pole, while selecting the correct ones, came from the work of R. Bruce Nicklas and his colleagues at Duke University (Nicklas and Koch, 1969).

By the late 1960s scientists knew that unipolar kinetochore-to-pole attachments are unstable and easily come undone. They also knew that by a somewhat random process, stable bioriented attachments are eventually established. “I had a sequence of pictures...