Casting for Chromosomes
Microtubules "fish" for chromosomes by growing toward them and then, at a random moment, quickly shrinking (see arrows). This process, called "dynamic instability," continues until the microtubules attach to a special region on the chromosome called the "kinetochore." Salmon and a former graduate student, Richard Walker, first observed dynamic instability in 1985 and helped settle a year-long controversy created when two biologists at the University of California, San Francisco, proposed the theory.



Microtubule Gynastics
The laser optical trap measures the strength and flexibility of microtubules. Salmon's graduate student, Phong Tran, made these images by clamping one end of a microtubule (shadowed region) to a slide, attaching a glass bead (bright dot) to the other end, and moving the bead with the optical trap's laser beam. The microtubule bends as far as it can, then springs back.


Images courtesy of Phong Tran