Loss of Drosophila melanogaster TRPA1 Function Affects “Siesta” Behavior but Not Synchronization to Temperature Cycles

Abstract

To maintain synchrony with the environment, circadian clocks use a wide range of cycling sensory cues that provide input to the clock (zeitgebers), including environmental temperature cycles (TCs). There is some knowledge about which clock neuronal groups are important for temperature synchronization, but we currently lack knowledge on the temperature receptors and their signaling pathways that feed temperature information to the (neuronal) clock. Since TRPA1 is a well-known thermosensor that functions in a range of temperature-related behaviors, and it is potentially expressed in clock neurons, we set out to test the putative role of TRPA1 in temperature synchronization of the circadian clock. We found that flies lacking TRPA1 are still able to synchronize their behavioral activity to TCs comparable to wild-type flies, both in 16°C : 25°C and 20°C : 29°C TCs. In addition, we found that flies lacking TRPA1 show higher activity levels during the middle of the warm phase of 20°C : 29°C TCs, and we show that this TRPA1-mediated repression of locomotor activity during the "siesta" is caused by a lack of sleep. Based on these data, we conclude that the TRPA1 channel is not required for temperature synchronization in this broad temperature range but instead is required to repress activity during the warm part of the day.

Reorganization of Sleep by Temperature in Drosophila Requires Light, the Homeostat, and the Circadian Clock

“…This serves as a second mechanism for linking changes in daytime and nighttime sleep. The sensors required for heat effects are unknown, but recent studies have suggested that both dTrpA1 and Ir25a are important in communication of temperature information to clock and activity circuits [46, 47]. …”

The role of PDF neurons in setting the preferred temperature before dawn in Drosophila

“…Because the circadian clock is entrained by light-dark and temperature cycles (Busza et al, 2007; Glaser and Stanewsky, 2005; Miyasako et al, 2007; Yoshii et al, 2010), it is possible that ambient temperature information via ACs is used for temperature entrainment. Although TRPA1 itself is neither required for temperature entrainment (Das et al, 2016; Roessingh et al, 2015) nor temperature compensation (Table 2), TRPA1 expression in TrpA1 SH -Gal4 + neurons is required for exhibiting a ‘siesta’ during temperature cycles (Das et al, 2016; Roessingh et al, 2015). Because AC neurons also integrate the temperature information from Pyx-Gal4 expressing neurons and PYX has a function in synchronizing the circadian clock to temperature cycles (Tang et al, 2013; Wolfgang et al, 2013), it is possible that AC neurons influence temperature entrainment.…”

Regulation of sleep plasticity by a thermo-sensitive circuit in Drosophila

“…Sleep was defined as a period of inactivity of at least 5 min67. A modified version of a previously described Microsoft Excel script68 was used to measure all sleep parameters detailed in this article. Siesta sleep onset is defined as the latency of the first sleep bout and siesta offset as the end of the last sleep episode.…”