acts During Development to Determine the Phase of Adult Circadian Behavior.

The circadian clock enables organisms to optimize their metabolism, physiology, and behavior with the time-of-day. However, circadian rhythms benefit organisms only if they are properly synchronized with the day/night cycle; circadian misalignment can have detrimental effects on animals' wellbeing and survival. We previously showed that in , loss of the microRNA advances the phase of circadian evening locomotor activity by several hours under constant darkness conditions.

Biological rhythms: In the sea, two clocks are better than one.

How marine species cope with both diurnal and tidal cycles is unclear. A new study in crustaceans identifies distinct brain cells that exhibit either 24- or 12.4-hour rhythms of gene expression, thus providing a mechanism for tracking multiple environmental cycles.

Biological rhythms: Living your life, one half-day at a time.

Circadian rhythms play a preeminent role in our life, organizing our physiology and behavior on a daily basis to resonate with our fluctuating environment. However, recent studies reveal that hundreds of mouse and human genes are expressed with a 12-h pattern. We take a close look at mammalian 12-h rhythms, their potential mechanisms and functions, and evidence linking them to circatidal rhythms, which enable marine animals to adapt to tides.

Crosstalk between the circatidal and circadian clocks mediates behavioral adaptation to tidal patterns.

The ability to anticipate tides is critical for a wide range of marine organisms, but this task is complicated by the diversity of tidal patterns on Earth. Previous findings suggest that organisms whose geographic range spans multiple types of tidal cycles can produce distinct patterns of rhythmic behavior that correspond to the tidal cycles they experience. How this behavioral plasticity is achieved, however, is unclear.

Fly into tranquility: GABA's role in Drosophila sleep.

Sleep is conserved across the animal kingdom, and Drosophila melanogaster is a prime model to understand its intricate circadian and homeostatic control. GABA (gamma-aminobutyric acid), the brain's main inhibitory neurotransmitter, plays a central role in sleep. This review delves into GABA's complex mechanisms of actions within Drosophila's sleep-regulating neural networks.

Cnidarians are CLOCKing in.

Studies of the starlet sea anemone provide important insights into the early evolution of the circadian clock in animals.

Clocks at sea: the genome-editing tide is rising.

The coastline is a particularly challenging environment for its inhabitants. Not only do they have to cope with the solar day and the passing of seasons, but they must also deal with tides. In addition, many marine species track the phase of the moon, especially to coordinate reproduction.

ATXN2 is a target of N-terminal proteolysis.

Spinocerebellar ataxia 2 (SCA2) is a neurodegenerative disorder caused by the expansion of the poly-glutamine (polyQ) tract of Ataxin-2 (ATXN2). Other polyQ-containing proteins such as ATXN7 and huntingtin are associated with the development of neurodegenerative diseases when their N-terminal polyQ domains are expanded. Furthermore, they undergo proteolytic processing events that produce N-terminal fragments that include the polyQ stretch, which are implicated in pathogenesis.

Behavioral circatidal rhythms require Bmal1 in Parhyale hawaiensis.

Organisms living in the intertidal zone are exposed to a particularly challenging environment. In addition to daily changes in light intensity and seasonal changes in photoperiod and weather patterns, they experience dramatic oscillations in environmental conditions due to the tides. To anticipate tides, and thus optimize their behavior and physiology, animals occupying intertidal ecological niches have acquired circatidal clocks.

PERIOD Phosphoclusters Control Temperature Compensation of the Circadian Clock.

Ambient temperature varies constantly. However, the period of circadian pacemakers is remarkably stable over a wide-range of ecologically- and physiologically-relevant temperatures, even though the kinetics of most biochemical reactions accelerates as temperature rises. This thermal buffering phenomenon, called temperature compensation, is a critical feature of circadian rhythms, but how it is achieved remains elusive.

Astrocytic GABA transporter controls sleep by modulating GABAergic signaling in Drosophila circadian neurons.

A precise balance between sleep and wakefulness is essential to sustain a good quality of life and optimal brain function. GABA is known to play a key and conserved role in sleep control, and GABAergic tone should, therefore, be tightly controlled in sleep circuits. Here, we examined the role of the astrocytic GABA transporter (GAT) in sleep regulation using Drosophila melanogaster.

Dopaminergic Ric GTPase activity impacts amphetamine sensitivity and sleep quality in a dopamine transporter-dependent manner in Drosophila melanogaster.

Dopamine (DA) is required for movement, sleep, and reward, and DA signaling is tightly controlled by the presynaptic DA transporter (DAT). Therapeutic and addictive psychostimulants, including methylphenidate (Ritalin; MPH), cocaine, and amphetamine (AMPH), markedly elevate extracellular DA via their actions as competitive DAT inhibitors (MPH, cocaine) and substrates (AMPH). DAT silencing in mice and invertebrates results in hyperactivity, reduced sleep, and blunted psychostimulant responses, highlighting DAT's essential role in DA-dependent behaviors.

PSI controls circadian period and the phase of circadian behavior under temperature cycle via splicing.

The circadian pacemaker consists of transcriptional feedback loops subjected to post-transcriptional and post-translational regulation. While post-translational regulatory mechanisms have been studied in detail, much less is known about circadian post-transcriptional control. Thus, we targeted 364 RNA binding and RNA associated proteins with RNA interference.

Cryptochrome: Variations in Blue.

CRYPTOCHROMES (CRYs) are structurally related to ultraviolet (UV)/blue-sensitive DNA repair enzymes called photolyases but lack the ability to repair pyrimidine dimers generated by UV exposure. First identified in plants, CRYs have proven to be involved in light detection and various light-dependent processes in a broad range of organisms. In , CRY's best understood role is the cell-autonomous synchronization of circadian clocks.

Guided inquiry activity linking thermodynamic parameters of protein unfolding to structure using differential scanning fluorimetry data in the biophysical chemistry classroom.

Visualizations are useful tools for helping students to understand chemistry concepts at the particulate level. A classroom activity was developed based on learning theory and evidence-based practices, combining protein visualization with thermodynamic parameters from differential scanning fluorimetry (DSF) data analysis. Coding of student responses showed that many students were able to establish the desired connections among protein structure, thermodynamic parameters, and experimental data analysis, while a few did not recognize all the differences between the folded and unfolded forms of the protein.

Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock.

The brain clock that drives circadian rhythms of locomotor activity relies on a multi-oscillator neuronal network. In addition to synchronizing the clock with day-night cycles, light also reformats the clock-driven daily activity pattern. How changes in lighting conditions modify the contribution of the different oscillators to remodel the daily activity pattern remains largely unknown.

Neural Network Interactions Modulate CRY-Dependent Photoresponses in .

Light is one of the chief environmental cues that reset circadian clocks. In , CRYPTOCHROME (CRY) mediates acute photic resetting of circadian clocks by promoting the degradation of TIMELESS in a cell-autonomous manner. Thus, even circadian oscillators in peripheral organs can independently perceive light in However, there is substantial evidence for nonautonomous mechanisms of circadian photoreception in the brain.

SIK3-HDAC4 signaling regulates circadian male sex drive rhythm via modulating the DN1 clock neurons.

The physiology and behavior of many organisms are subject to daily cycles. In the daily locomotion patterns of single flies are characterized by bursts of activity at dawn and dusk. Two distinct clusters of clock neurons-morning oscillators (M cells) and evening oscillators (E cells)-are largely responsible for these activity bursts.

miR-124 Regulates the Phase of Drosophila Circadian Locomotor Behavior.

Unlabelled: Animals use circadian rhythms to anticipate daily environmental changes. Circadian clocks have a profound effect on behavior. In Drosophila, for example, brain pacemaker neurons dictate that flies are mostly active at dawn and dusk.

Calcium and SOL Protease Mediate Temperature Resetting of Circadian Clocks.

Circadian clocks integrate light and temperature input to remain synchronized with the day/night cycle. Although light input to the clock is well studied, the molecular mechanisms by which circadian clocks respond to temperature remain poorly understood. We found that temperature phase shifts Drosophila circadian clocks through degradation of the pacemaker protein TIM.

The molecular ticks of the Drosophila circadian clock.

is a powerful model to understand the mechanisms underlying circadian rhythms. The molecular clock is comprised of transcriptional feedback loops. The expressions of the critical transcriptional activator CLK and its repressors PER and TIM are under tight transcriptional control.

Morning and evening oscillators cooperate to reset circadian behavior in response to light input.

Light is a crucial input for circadian clocks. In Drosophila, short light exposure can robustly shift the phase of circadian behavior. The model for this resetting posits that circadian photoreception is cell autonomous: CRYPTOCHROME senses light, binds to TIMELESS (TIM), and promotes its degradation, which is mediated by JETLAG (JET).