Stress-response genes controlled by the circadian clock are shown to be up-regulated in old fruit flies (Drosophila melanogaster) in a study published in Nature Communications this week. Disruption of cellular circadian clocks - the rhythmic expression of genes in 24-hour cycles - is usually associated with accelerated aging and other health issues, but the new finding sheds light on how the circadian clock might protect organisms during aging.

Circadian rhythms regulate a range of processes, such as metabolism and behaviour, through the oscillating expression of circadian clock genes over approximately 24-hour periods. To identify how the circadian clock genes change with age, Jadwiga Giebultowicz, David Hendrix and colleagues compared gene expression in young and old flies throughout the day. They found a group of genes that did not oscillate in young flies but did oscillate in old ones. They called these genes “late-life cyclers” and found that many of these genes are associated with response to oxidative stress, a form of cellular damage that increases with aging.

These results suggest that the circadian clock helps organisms adapt to oxidative stress and aging. Although many cellular circadian clock genes are conserved from flies to humans, we do not yet know if this protective process is conserved in mammals.