A molecule controlling daily rhythms in fruit flies is regulated by a system that removes faulty genetic messages

Depletion of key NMD factors in circadian pacemaker neurons decreased the amplitude of circadian locomotor behaviors.

• The nonsense-mediated mRNA decay (NMD) pathway is involved in regulating circadian rhythms in Drosophila.
• Manipulating the NMD pathway in specific clock neurons can alter the duration of free-running locomotor rhythms.
• Arrhythmic Clock mutants showed increased NMD activity in PDF-expressing neurons compared to wild-type.
• Hypomorphic mutations in Smg5 or Smg6 led to impaired circadian behaviors despite normal development of clock neurons.
• Changes in the levels of the cAMP response element-binding protein B (CrebB) were observed in NMD mutants.
• Overexpression of a transcriptional repressor form of CrebB could restore normal locomotor rhythms in Smg5-depleted flies.

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