The Drosophila circadian phase response curve to light: Conservation across seasonally relevant photoperiods and anchorage to sunset

Dollish, Hannah K.; Kaladchibachi, Sevag; Negelspach, David C.; Fernandez, Fabian-Xosé

doi:10.1016/j.physbeh.2021.113691

Cited by 4 publications

(3 citation statements)

References 81 publications

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“…This may therefore appear as a confound in our experimental design. However, instantaneous effects of light on the clock around mid-day (which is where our transitions occur) are almost non-existent [2,18,35,36]. Thus, our results described above are consistent with the speed of internal clocks being modulated by long durations, and continuous effects, of light.…”

Section: Resultssupporting

confidence: 81%

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment inDrosophila melanogaster

Abhilash

Shafer

2022

Preprint

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Circadian rhythms in physiology and behavior have near 24-hour periodicities that must adjust to the exact 24-hour geophysical cycles on earth to ensure stable and adaptive daily timing, a phenomenon referred to as entrainment. Entrainment can either occur via instantaneous shifts in the phase of the clock, a process referred to as non-parametric entrainment, or by light acting continuously to alter the speed of the clock, a process referred to as parametric entrainment. Though typically studied in isolation, real-world entrainment involves both parametric and non-parametric processes. While Drosophila melanogaster has been a powerful model organism for understanding the molecular and neuronal underpinnings of entrainment, the vast majority of the work on entrainment in this species has focused on non-parametric light effects. Though parametric effects of light have been described for D. melanogaster, there have been few studies examining the mechanisms underlying such effects. This has been due, in large part, to the fact that the fly’s circadian system does not free-run strongly under constant light conditions, which is required to experimentally address parametric effects of light. In this study, we demonstrate that light has robust parametric effects on the Drosophila circadian clock and that the timing of daily activity is strongly influenced by these effects, even under the standard step-function light/dark cycles employed by the field. We also show that parametric effects of light depend on external photoreceptors and, to a surprising extent, on the blue light photoreceptor cryptochrome. Furthermore, we introduce ramped light cycles as an entrainment paradigm that produces entrainment features that are similar to those seen in mammalian systems, in that they eliminate the confounding effects of the large startle responses displayed by flies under step function light/dark cycles and require multiple days for re-entrainment to shifted cycles. These features make possible a new experimental approach to understanding the mechanisms underlying entrainment in the fly.

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Section: Resultssupporting

confidence: 81%

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment inDrosophila melanogaster

Abhilash

Shafer

2022

Preprint

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“…This may therefore appear as a confound in our experimental design. However, instantaneous effects of light on the clock around mid-day (which is where our transitions occur) are almost non-existent [ 2 , 18 , 35 , 36 ]. Our results are therefore consistent with the speed of internal clocks being modulated by long durations, and continuous effects, of light.…”

Section: Resultsmentioning

confidence: 99%

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment in Drosophila melanogaster

Abhilash,

Shafer

2023

Proc. R. Soc. B.

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Circadian rhythms in physiology and behaviour have near 24 h periodicities that must adjust to the exact 24 h geophysical cycles on earth to ensure adaptive daily timing. Such adjustment is called entrainment. One major mode of entrainment is via the continuous modulation of circadian period by the prolonged presence of light. Although Drosophila melanogaster is a prominent insect model of chronobiology, there is little evidence for such continuous effects of light in the species. In this study, we demonstrate that prolonged light exposure at specific times of the day shapes the daily timing of activity in flies. We also establish that continuous UV- and blue-blocked light lengthens the circadian period of Drosophila and provide evidence that this is produced by the combined action of multiple photoreceptors which, includes the cell-autonomous photoreceptor cryptochrome . Finally, we introduce ramped light cycles as an entrainment paradigm that produces light entrainment that lacks the large light-driven startle responses typically displayed by flies and requires multiple days for entrainment to shifted cycles. These features are reminiscent of entrainment in mammalian models systems and make possible new experimental approaches to understanding the mechanisms underlying entrainment in the fly.

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“…The potential of RDLNs in chronobiological studies is underlined by field work on subterranean rodents, where burrow emergence behavior strongly modifies realized light cycles and indicates complex circadian entrainment processes 52 , 78 , 79 . Behavioral rhythmicity differences between laboratory studies and wild or semi-natural conditions are common, which is typically attributed to the artificial conditions in the laboratory 71 , 80 – 86 . Where wild investigations are not possible, understanding of RDLNs can help develop experimental procedures that more closely resemble nature and focus on the cues most relevant to the organism in the wild 87 .…”

Section: Resultsmentioning

confidence: 99%

Animal behavior is central in shaping the realized diel light niche

et al. 2022

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Animal behavior in space and time is structured by the perceived day/night cycle. However, this is modified by the animals’ own movement within its habitat, creating a realized diel light niche (RDLN). To understand the RDLN, we investigated the light as experienced by zooplankton undergoing synchronized diel vertical migration (DVM) in an Arctic fjord around the spring equinox. We reveal a highly dampened light cycle with diel changes being about two orders of magnitude smaller compared to the surface or a static depth. The RDLN is further characterized by unique wavelength-specific irradiance cycles. We discuss the relevance of RDLNs for animal adaptations and interactions, as well as implications for circadian clock entrainment in the wild and laboratory.

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The Drosophila circadian phase response curve to light: Conservation across seasonally relevant photoperiods and anchorage to sunset

Cited by 4 publications

References 81 publications

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment inDrosophila melanogaster

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment inDrosophila melanogaster

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment in Drosophila melanogaster

Animal behavior is central in shaping the realized diel light niche

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