Lauren M. Head, Xin Tang, Sean E. Hayley, Tadahiro Goda, Yujiro Umezaki, Elaine C. Chang, Jennifer R. Leslie, Mana Fujiwara, Paul A. Garrity, Fumika N. Hamada

Ambient light affects multiple physiological functions and behaviors, such as circadian rhythms, sleep-wake activities, and development, from flies to mammals [1-6]. Mammals exhibit a higher body temperature when exposed to acute light compared to when they are exposed to the dark, but the underlying mechanisms are largely unknown [7-10]. The body temperature of small ectotherms, such as Drosophila, relies on the temperature of their surrounding environment, and these animals exhibit a robust temperature preference behavior [11-13]. Here, we demonstrate that Drosophila prefer a ∼1° higher temperature when exposed to acute light rather than the dark. This acute light response, light-dependent temperature preference (LDTP), was observed regardless of the time of day, suggesting that LDTP is regulated separately from the circadian clock. However, screening of eye and circadian clock mutants suggests that the circadian clock neurons posterior dorsal neurons 1 (DN1ps) and Pigment-Dispersing Factor Receptor (PDFR) play a role in LDTP. To further investigate the role of DN1ps in LDTP, PDFR in DN1ps was knocked down, resulting in an abnormal LDTP. The phenotype of the pdfr mutant was rescued sufficiently by expressing PDFR in DN1ps, indicating that PDFR in DN1ps is responsible for LDTP. These results suggest that light positively influences temperature preference via the circadian clock neurons, DN1ps, which may result from the integration of light and temperature information. Given that both Drosophila and mammals respond to acute light by increasing their body temperature, the effect of acute light on temperature regulation may be conserved evolutionarily between flies and humans.