M arie Delattre, a biologist at the École Normale Supérieure de Lyon, has studied the nematode Mesorhabditis belari for nearly a decade now. The microscopic worm first caught her attention for its ...

When you think of a chromosome, you might imagine an X-shaped structure. But chromosomes take this shape only during cell division; the rest of the time, they adopt a structure that looks amorphous ...