Phase-Shifting the Fruit Fly Clock without Cryptochrome

Kistenpfennig, Christa; Hirsh, Jay; Yoshii, Taishi; Helfrich‐Förster, Charlotte

doi:10.1177/0748730411434390

Cited by 32 publications

(38 citation statements)

References 41 publications

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“…To confirm this, in Figure 3C we tested cry null flies, cry 02 , in the same paradigm. As expected, these flies show highly muted phase advance amplitudes [24], [25], with none of the light pulses resulting in a statistically significant phase advance relative to the no pulse control. Comparing the data in Figure 3 for each light pulse time as a function of genotype, only the 100 min light pulse for cry is significantly different from w 1118 or norpA (P<0.001, ANOVA).…”

Section: Resultssupporting

confidence: 75%

“…Wild type flies show a graded response to increasing blue light illumination, with a half-maximal advance at 3 nw/cm 2 , and large amplitude 6 hr phase advances at 33 nw/cm 2 (Figure 4A). This amplitude is saturating as shown using a similar though not identically timed 360 min light pulse [24]. We performed similar studies using norpA (Figure 4B) and cry 02 (Figure 4C).…”

Section: Resultssupporting

confidence: 72%

“…In contrast, the responses in cry 02 flies are severely muted, showing a ∼1.5 hr phase advance at all intensities. Similarly muted phase shift responses have long been seen for cry mutants [21], [24], [25], with [24] showing significant phase shifts at ZT21 and 23.…”

Section: Resultssupporting

confidence: 54%

“…The alternative assay examines phase advances in response to graded intensities of 360 min intervals of blue light centered at ZT21, using this time point instead of ZT20 to avoid going into the phase delay region of the phase response curve [24], [25]. Wild type flies show a graded response to increasing blue light illumination, with a half-maximal advance at 3 nw/cm 2 , and large amplitude 6 hr phase advances at 33 nw/cm 2 (Figure 4A).…”

Section: Resultsmentioning

confidence: 99%

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Exquisite Light Sensitivity of Drosophila melanogaster Cryptochrome

et al. 2013

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Drosophila melanogaster shows exquisite light sensitivity for modulation of circadian functions in vivo, yet the activities of the Drosophila circadian photopigment cryptochrome (CRY) have only been observed at high light levels. We studied intensity/duration parameters for light pulse induced circadian phase shifts under dim light conditions in vivo. Flies show far greater light sensitivity than previously appreciated, and show a surprising sensitivity increase with pulse duration, implying a process of photic integration active up to at least 6 hours. The CRY target timeless (TIM) shows dim light dependent degradation in circadian pacemaker neurons that parallels phase shift amplitude, indicating that integration occurs at this step, with the strongest effect in a single identified pacemaker neuron. Our findings indicate that CRY compensates for limited light sensitivity in vivo by photon integration over extraordinarily long times, and point to select circadian pacemaker neurons as having important roles.

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Section: Resultssupporting

confidence: 75%

Section: Resultssupporting

confidence: 72%

Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

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Exquisite Light Sensitivity of Drosophila melanogaster Cryptochrome

et al. 2013

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“…3a) 21 . As previously reported 3,22 , cry 01 displays severely impaired phase shifting to early or late night pulses (Fig. 3a).…”

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confidence: 89%

A rhodopsin in the brain functions in circadian photoentrainment in Drosophila

Baik

Holmes

et al. 2017

Nature

125

162

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Animals partition their daily activity rhythms through their internal circadian clocks, which are synchronized by oscillating day-night cycles of light. The fruit fly, Drosophila melanogaster, senses day/night cycles in part through rhodopsin-dependent light reception in the compound eye, and photoreceptor cells in the Hofbauer-Buchner (H-B) eyelet1. However, a more significant light entrainment pathway is mediated in central pacemaker neurons in the brain. The Drosophila circadian clock is extremely light sensitive. However, the only known light sensor in pacemaker neurons, the flavoprotein, cryptochrome (Cry)2,3, responds only to high levels of light in vitro4. These observations indicate the existence of an additional light-sensing pathway in fly pacemaker neurons5. Here, we identified an uncharacterized rhodopsin, Rh7, which functions in circadian light entrainment through circadian pacemaker neurons in the brain. The pacemaker neurons respond to violet light, which was dependent on Rh7. While loss of either cry or rh7 caused minor affects on photoentrainment, the defects in the double mutant were profound. The circadian photoresponse to constant light was impaired in the rh7 mutant, especially under dim light. The demonstration that Rh7 functions in circadian pacemaker neurons represents the first role for an opsin in the central brain.

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Four of the six Drosophila rhodopsin‐expressing photoreceptors can mediate circadian entrainment in low light

Saint-Charles

Michard-Vanhée

Alejevski

et al. 2016

J of Comparative Neurology

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Light is the major stimulus for the synchronization of circadian clocks with day-night cycles. The light-driven entrainment of the clock that controls rest-activity rhythms in Drosophila relies on different photoreceptive molecules. Cryptochrome (CRY) is expressed in most brain clock neurons, whereas six different rhodopsins (RH) are present in the light-sensing organs. The compound eye includes outer photoreceptors that express RH1 and inner photoreceptors that each express one of the four rhodopsins RH3-RH6. RH6 is also expressed in the extraretinal Hofbauer-Buchner eyelet, whereas RH2 is only found in the ocelli. In low light, the synchronization of behavioral rhythms relies on either CRY or the canonical rhodopsin phototransduction pathway, which requires the phospholipase C-β encoded by norpA (no receptor potential A). We used norpA(P24) cry(02) double mutants that are circadianly blind in low light and restored NORPA function in each of the six types of photoreceptors, defined as expressing a particular rhodopsin. We first show that the NORPA pathway is less efficient than CRY for synchronizing rest-activity rhythms with delayed light-dark cycles but is important for proper phasing, whereas the two light-sensing pathways can mediate efficient adjustments to phase advances. Four of the six rhodopsin-expressing photoreceptors can mediate circadian entrainment, and all are more efficient for advancing than for delaying the behavioral clock. In contrast, neither RH5-expressing retinal photoreceptors nor RH2-expressing ocellar photoreceptors are sufficient to mediate synchronization through the NORPA pathway. Our results thus reveal different contributions of rhodopsin-expressing photoreceptors and suggest the existence of several circuits for rhodopsin-dependent circadian entrainment. J. Comp. Neurol. 524:2828-2844, 2016. © 2016 Wiley Periodicals, Inc.

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Phase-Shifting the Fruit Fly Clock without Cryptochrome

Cited by 32 publications

References 41 publications

Exquisite Light Sensitivity of Drosophila melanogaster Cryptochrome

Exquisite Light Sensitivity of Drosophila melanogaster Cryptochrome

A rhodopsin in the brain functions in circadian photoentrainment in Drosophila

Four of the six Drosophila rhodopsin‐expressing photoreceptors can mediate circadian entrainment in low light

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