FOCAL POINT Paul Maddox (left), Anne-Marie Ladouceur (right), and Jonas Dorn determined what factors dictate the size of chromosomes in early C. elegans embryos. They found that the length of chromsomes depends on nuclear and cell size. The Ran GTP gradient across the nuclear membrane also affects chromosome compaction. In a control embryo, the chromosomes get smaller from division to division (top row). But in an embryo lacking RCC1, which helps establish the Ran GTP gradient, the chromosomes shrink faster (bottom row).
PHOTO COURTESY OF CARLOS PATINO DESCOVICH