Data for: Altered Circadian Rhythm, Sleep, and Rhodopsin 7-Dependent Shade Preference During Diapause in Drosophila Melanogaster

To survive adverse environments, many animals enter a dormant state such
as hibernation, dauer, or diapause. Various Drosophila species
undergo adult reproductive diapause in response to cool
temperatures and/or short day-length. While it is known that
flies are less active during diapause, an in-depth understanding of
diapause effects on circadian rhythms and sleep is lacking. Here
we show that, in diapause-inducing conditions, Drosophila
melanogaster exhibit altered circadian activity profiles,
including a severely reduced morning activity peak and an
advanced evening activity peak. Consequently, the flies have a
single activity peak at a time similar to when non-diapausing
flies have a siesta. Temperatures ≤15 °C, rather than short
day-length, primarily drive the behavior. At cool temperatures,
flies also rapidly enter a deep sleep state that lacks the sleep
cycles of flies at higher temperatures and requires
particularly high levels of stimulation for arousal. Furthermore,
we show that at 18–25 °C, flies prefer to siesta in the shade, a
preference that is virtually eliminated at 10 °C. Resting in the
shade is driven by an aversion to blue light, sensed by rhodopsin 7 (Rh7)
outside of the eyes. Flies at 10 ˚C show neuronal markers of
elevated sleep pressure, including increased expression of
Bruchpilot and elevated Ca2+ in the R5 ellipsoid body
neurons. Therefore, sleep pressure might overcome blue light
aversion. Thus at temperatures known to cause reproductive arrest,
preserve germline stem cells, and extend lifespan, Drosophila
melanogaster are prone to deep sleep and exhibit dramatically altered -
yet rhythmic - daily activity patterns.