The switch made from a single molecule

Scientists discover an "on-demand" male contraceptive capable of temporarily disabling sperm motility in mice. Balbach et al. describes how a single dose of soluble adenylyl cyclase inhibitor can render male mice infertile within 30 minutes, and return them to full fertility the next day

A Flip of a Genetic Switch: Stopping a Rare Childhood Cancer in Its Tracks

The Mass of a Single Star (other than the Sun) has Been Directly Measured for the First Time