One seasonal clock fits all?

Michel, Stephan; Kervezee, Laura

doi:10.1007/s00359-023-01680-4

Cited by 4 publications

References 72 publications

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A clock for all seasons

Helfrich-Förster,

Rieger

2024

J Comp Physiol A

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Circadian clocks play an essential role in adapting locomotor activity as well as physiological, and metabolic rhythms of organisms to the day-night cycles on Earth during the four seasons. In addition, they can serve as a time reference for measuring day length and adapt organisms in advance to annual changes in the environment, which can be particularly pronounced at higher latitudes. The physiological responses of organisms to day length are also known as photoperiodism. This special issue of the Journal of Comparative Physiology A aims to account for diurnal and photoperiodic adaptations by presenting a collection of ten review articles, five original research articles, and three perspective pieces. The contributions include historical accounts, circadian and photoperiodic clock models, epigenetic, molecular, and neuronal mechanisms of seasonal adaptations, latitudinal differences in photoperiodic responses and studies in the wild that address the challenges of global change.

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A clock for all seasons

Helfrich-Förster,

Rieger

2024

J Comp Physiol A

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Neuropeptide Dynamics Coordinate Layered Plasticity Mechanisms Adapting Drosophila Circadian Behavior to Changing Environment

Chatterjee,

De,

Martin

et al. 2024

Preprint

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The Drosophila brain contains distinct sets of circadian oscillators responsible for generating the morning and evening bouts of locomotor activity, giving rise to a bimodal rest-activity pattern in light-dark cycles. We lack a mechanistic understanding of how environmental changes reshape this daily profile of rest-activity pattern. Here, we uncover a seasonal switch mechanism that remodels the evening bout of activity. Under summer-like conditions, an environment favored by fruit flies in temperate climates, levels of the PDF neuropeptide diminish, triggering a cascade. Lowered PDFR signaling disinhibits GSK3/SGG to advance the evening output. Upon sensing PDF loss, the neural activity weakens in the DN1p-SIFa circuit, responsible for promoting afternoon rest; leading to an earlier appearance of the evening peak. At the same time, the functional connections from DN1p to LNd oscillators strengthen, consequently handing over the evening pacemaker role to the DN1ps. Taken together, our findings elucidate how environment-induced changes in PDFR signaling tip the balanced output of the clock network, aligning daily rhythms with seasonal time. Neuropeptide-driven parallel adjustment of clock circuitry and clock protein functioning likely represents a conserved strategy across animal species, enabling them to adapt their daily behavior to seasonal changes throughout the year.

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Widespread annual rhythms in pediatric emergencies

Tachinardi,

Witt,

et al. 2024

Preprint

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Assessments of emergency department (ED) utilization for specific medical conditions reveal distinct annual rhythms, providing valuable insights into risk factors and optimal clinical staffing. However, focusing on a single condition in isolation can lack essential context. Such rhythms may (i) depend on co-occurrence with other conditions, (ii) be obscured by systemic factors that influence all conditions similarly, or (iii) offer limited clinical utility without understanding their rhythmic effect sizes relative to other emergencies. Using a unified framework for analysis, we studied the annual variation in incidences of all chief complaints (CCs) from 1.5 million admissions to our pediatric ED and urgent care centers from 2010 to 2021, enabling comparison of seasonality, effect sizes, and interactions across all types of emergencies. Most CCs (~80%) had annual rhythms, with a range of phases. Specific patterns, such as spring and fall peaks in neurologic-, injury-, and psychiatric-related CCs, have immediate significance. For example, psychiatric emergencies, which the American Academy of Pediatrics has designated a national crisis, were among the largest rhythmic effect sizes of all CCs. Further evaluation integrating ICD-10 diagnoses identified patient subtypes for psychiatric and other CCs, suggesting distinct annual influences. Using counterpart data from across Brazil, we identified marked global differences in annual patterns of ED utilization, including psychiatric emergencies. Lastly, we identified CCs with large weekday effects, impacting care and staffing needs, especially when combined with annual rhythms.

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One seasonal clock fits all?

Cited by 4 publications

References 72 publications

A clock for all seasons

A clock for all seasons

Neuropeptide Dynamics Coordinate Layered Plasticity Mechanisms Adapting Drosophila Circadian Behavior to Changing Environment

Widespread annual rhythms in pediatric emergencies

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