Drosophila ebony activity is required in glia for the circadian regulation of locomotor activity

Previous studies suggest that glia may be required for normal circadian behavior, but glial factors required for rhythmicity have not been identified in any system. We show here that a circadian rhythm in Drosophila Ebony (N-beta-alanyl-biogenic amine synthetase) abundance can be visualized in adult glia and that glial expression of Ebony rescues the altered circadian behavior of ebony mutants. We demonstrate that molecular oscillator function and clock neuron output are normal in ebony mutants, verifying a role for Ebony downstream of the clock. Surprisingly, the ebony oscillation persists in flies lacking PDF neuropeptide, indicating it is regulated by an autonomous glial oscillator or another neuronal factor. The proximity of Ebony-containing glia to aminergic neurons and genetic interaction results suggest a function in dopaminergic signaling. We thus suggest a model for ebony function wherein Ebony glia participate in the clock control of dopaminergic function and the orchestration of circadian activity rhythms.