Morning and Evening Oscillators Cooperate to Reset Circadian Behavior in Response to Light Input

Lamba, Pallavi; Bilodeau-Wentworth, Diana; Emery, Patrick; Zhang, Yong

doi:10.1016/j.celrep.2014.03.044

Cited by 31 publications

(32 citation statements)

References 33 publications

(71 reference statements)

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“…This conclusion is also consistent with more recent data from Emery et al (Lamba et al, 2014). Our data here also point to a more important role of the LNds rather than the M cells: the LNds show more TIM degradation in response to firing and a bigger response to the CUL-3 knockdown, which correlates with the decrease in phase delay caused by the knockdown (Figure 8).…”

Section: Discussionsupporting

confidence: 94%

PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

Guo

Cerullo

Xiao

et al. 2014

eLife

104

124

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Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify five different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the five E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY.DOI: http://dx.doi.org/10.7554/eLife.02780.001

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Section: Discussionsupporting

confidence: 94%

PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

Guo

Cerullo

Xiao

et al. 2014

eLife

104

124

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“…Furthermore, while the sLNvs, DN1s and DN3s recover rhythmicity after receiving the 2 h advancing light pulse, the lLNvs do not and, LNds resynchronize faster than other groups [88]. These ex vivo results are in agreement with previous reports showing that both M and E clusters are involved in phase shift adjustment [90], and data indicating that TIM degradation within s‐LNvs is not necessary to respond to a phase advancing stimulus [91]. Together, these findings led to the hypothesis that LNd neurons are leading the resynchronization and phase shift of the network.…”

Section: A Flexible Network For a Changing Environmentsupporting

confidence: 92%

Communication between circadian clusters: The key to a plastic network

Beckwith

Ceriani

2015

FEBS Letters

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a b s t r a c tDrosophila melanogaster is a model organism that has been instrumental in understanding the circadian clock at different levels. A range of studies on the anatomical and neurochemical properties of clock neurons in the fly led to a model of interacting neural circuits that control circadian behavior. Here we focus on recent research on the dynamics of the multiple communication pathways between clock neurons, and, particularly, on how the circadian timekeeping system responds to changes in environmental conditions.It is increasingly clear that the fly clock employs multiple signalling cues, such as neuropeptides, fast neurotransmitters, and other signalling molecules, in the dynamic interplay between neuronal clusters. These neuronal groups seem to interact in a plastic fashion, e.g., rearranging their hierarchy in response to changing environmental conditions. A picture is emerging supporting that these dynamic mechanisms are in place to provide an optimal balance between flexibility and an extraordinary accuracy.

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“…This sug-gests that CRY-mediated light responsiveness is critical in the s-LNvs and that non s-LNvs possibly depend more on signals from the eye. These conclusions are supported by analysis of light-mediated TIM degradation in jet knockdown flies at ZT15 and ZT21, before and after TIM nuclear entry (Lamba et al 2014). A reduction of JET in the LNds at either time point has no effect on light-mediated TIM degradation in either LNds or LNvs, nor does it induce a phase response as compared to wildtype.…”

Section: Differences In Cry Expression and Light Responsesupporting

confidence: 63%

Coordination between Differentially Regulated Circadian Clocks Generates Rhythmic Behavior

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Young

2017

Cold Spring Harb Perspect Biol

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Specialized groups of neurons in the brain are key mediators of circadian rhythms, receiving daily environmental cues and communicating those signals to other tissues in the organism for entrainment and to organize circadian physiology. In Drosophila, the "circadian clock" is housed in seven neuronal clusters, which are defined by their expression of the main circadian proteins, Period, Timeless, Clock, and Cycle. These clusters are distributed across the fly brain and are thereby subject to the respective environments associated with their anatomical locations. While these core components are universally expressed in all neurons of the circadian network, additional regulatory proteins that act on these components are differentially expressed, giving rise to "local clocks" within the network that nonetheless converge to regulate coherent behavioral rhythms. In this review, we describe the communication between the neurons of the circadian network and the molecular differences within neurons of this network. We focus on differences in protein-expression patterns and discuss how such variation can impart functional differences in each local clock. Finally, we summarize our current understanding of how communication within the circadian network intersects with intracellular biochemical mechanisms to ultimately specify behavioral rhythms. We propose that additional efforts are required to identify regulatory mechanisms within each neuronal cluster to understand the molecular basis of circadian behavior. C ircadian rhythms are behavioral and physiological responses that allow anticipation of daily changes in the environment, such as day/ night cycles. Indeed, circadian rhythms are entrained by diurnal oscillations in light, temperature, and food availability, each of which can be considered a "zeitgeber," or "time giver." Such anticipatory behavior of daily events confers adaptive advantages on individuals that organize physiology around planetary rhythms, as well as within a species as a whole, for purposes of mating, cooperation, protection, etc. In a sense, rhythmic anticipation can be thought of as a primitive mechanism of planning and cognition.The circadian clock, consisting of transcriptional negative feedback loops, underlies the regulation of a ∼24-h behavioral rhythm. The molecular architecture of this feedback loop is conserved across the majority of multicellular organisms. In animals, the "master clock" is housed in specialized pacemaker neurons in the brain that coordinate various "peripheral clocks" throughout the organism to regulate daily physiological and behavioral changes.

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Morning and Evening Oscillators Cooperate to Reset Circadian Behavior in Response to Light Input

Cited by 31 publications

References 33 publications

PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

Communication between circadian clusters: The key to a plastic network

Coordination between Differentially Regulated Circadian Clocks Generates Rhythmic Behavior

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