FOCAL POINT (Left to right) Nathan Goehring, Stephan Grill, Carsten Hoege, and Anthony Hyman investigated what preserves anterior–posterior polarity in the single-celled C. elegans embryo. The team found that the polarity-defining PAR proteins can move freely between the anterior and posterior portions of the membrane. Their work also suggests that the actomyosin skeleton beneath the cell membrane doesn't help maintain polarity. As these before (far right, left panel) and after (right panel) images show, the embryo remains polarized after treatment with cytochalasin D, which disrupts the actomyosin cytoskeleton.

PHOTO COURTESY OF ALEX BIRD