In mammals, astrocytes located among the central clock neurons in the SCN show robust oscillations in Per-reporter. Therefore, we investigated whether astrocytes located in the central brain neuropil are PER-positive in flies. These cells were marked with GFP via alrm-GAL4 driver and due to the leakiness of nuclear GFP also show some projections that extended into the neuropil (Figure 6C). GFP-positive astrocytes were examined in several areas of the central brain but PER protein staining was not detected in any of these cells at either ZT22 or ZT10 while nearby ventral lateral pacemaker neurons were PER-positive at ZT22 as expected (Figures 6B,C).