Circadian rhythm of melatonin in the brain of the face fly, Musca autumnalis De Geer.

Melatonin was radioimmunoassayed in extracts from brains of Musca autumnalis De Geer, the face fly, obtained 4h apart during 24h in 3 series pools of over 2 dozen brains at each of 6 or 7 circadian times. A circadian rhythm in the data expressed as percent of mean was demonstrated by the population-mean cosinor method. Face flies thus offer themselves for studies of melatonin-mediated chronomodulation by feedsideward mechanisms.