The up s ide of a gas shortage T he key to building strong bones and healthy joints is oxygen scarcity in the developing embryo. As Provot et al. show on page 451, a protein activated by low oxygen levels orchestrates the formation of limb bones and joints. The work demonstrates that one function of the protein is spurring differentiation of cartilage-constructing chondrocytes. An embryo acquir...

BACKGROUND In early 2001 Australia experienced a sudden reduction in the availability of heroin which had widespread effects on illicit drug markets across the country. The consequences of this event, commonly referred to as the Australian 'heroin shortage', have been extensively studied and there has been considerable debate as to the causes of the shortage and its implications for drug policy...