Dissection of central clock function inDrosophilathrough cell-specific CRISPR-mediated clock gene disruption

In Drosophila , ~150 neurons expressing molecular clock proteins regulate circadian behavior. Sixteen of these clock neurons secrete the neuropeptide Pdf and have been called “master pacemakers” because they are essential for circadian rhythms. A subset of Pdf + neurons (the morning oscillator) regulates morning activity and communicates with other non-Pdf + neurons, including a subset called the evening oscillator. It is assumed that the molecular clock in Pdf + neurons is required for these functions. To test this, we developed and validated Gal4-UAS based CRISPR tools for cell-specific disruption of key molecular clock components, period and timeless . While loss of the molecular clock in both the morning and evening oscillators eliminates circadian locomotor activity, the molecular clock in either oscillator alone is sufficient for circadian locomotor activity. This suggests that clock neurons do not act in a hierarchy but as a distributed network to regulate circadian activity.