Temperature Sensation and Integration in the Drosophila Circadian Clock

Circadian clocks are entrained by zeitgebers, environmental cues such as light and temperature that adapt living organisms to the physical rhythms of the earth. Although temperature has been shown to be a major zeitgeber and can entrain the circadian clock of Drosophila, the neural and molecular mechanisms by which circadian clocks respond to temperature remain poorly understood. In our work, we use in vivo calcium imaging to characterize the temperature response of clock neurons in Drosophila to temperature modulation. We show that a selective group of clock neurons responds to temperature changes and that dorsal neurons (DNs) are excited by cooling and inhibited by warming. We further investigated the physiological input pathway of temperature sensing into the circadian clock. We find that arista and chordotonal organs are both critical factors that contribute to the response of circadian neurons to temperature modulation. Our work reveals that clock neurons respond to temperature changes through multiple temperature input pathways, suggesting a complex network similar to the entrainment of circadian clocks by light input.