Biology subjects

Louis, V.

Publications and source records attributed to Louis, V..

4 recordsLinked to original sources

bioRxiv2026

Membrane proteomics of the Drosophila circadian neural network

Circadian behaviors are controlled by dedicated brain pacemaker neurons, whose activity oscillate during the day and the night. The Drosophila brain contains ca. 240 such neurons. Their molecular clock is synchronized, but the phase of their rhythmic neural activity differs dramatically between functional groups. This explains how specific circadian neurons can for example promote morning or evening locomotor activity. To understand in depth how the circadian network functions, we surveyed its membrane proteome in the morning and evening, using in situ protein labeling and mass spectrometry. In addition to detecting known regulators of circadian behavior, we identified novel membrane or membrane-associated proteins present in circadian neurons. Through genetic screens, we found that many of these proteins regulate circadian behavior. In particular, Piezo regulates morning activity specifically under short photoperiod, and its loss compromises the structural plasticity of the clock neurons controlling locomotion at dawn. Our work thus illustrates the power of proteome-guided genetic screens to understand the mechanisms underlying circadian behavior.

neuroscience↗

bioRxiv2026

The CK2 and DBT kinases promote temperature compensation of the Drosophila circadian clock via distinct pathways

Circadian ([~]24 h) rhythms are essential for the survival of most organisms, as they optimize physiology and behavior with the time of day. They are defined by three fundamental properties: they are driven by a self-sustained molecular oscillator, entrained by environmental cues such as light and temperature, and temperature-compensated, whereby circadian period remains close to 24 h over a physiological range of temperatures. The molecular basis of temperature compensation remains incompletely understood. Here, we build on previous studies supporting a conserved and important role for phosphorylation-dependent mechanisms in the control of temperature compensation. We found that reducing the activity of two highly conserved circadian kinases, DBT (casein kinase [CK] 1) and CK2, disrupts temperature compensation in Drosophila. Genetic analyses indicate that DBT and CK2 act through distinct pathways that have additive effects on temperature compensation. DBT acts through the perShort phosphorylation cluster and the S47 phosphodegron of the core clock protein PER, both of which are required for normal thermal compensation. In contrast, CK2 acts through a phosphocluster in TIM as well as PER S45 residue. Interestingly, simultaneous disruption of both pathways causes accumulation of hyperphosphorylated PER, which is inefficiently cleared from the nucleus of circadian pacemaker neurons. Combined with previous work, our findings support a central and unifying role for nuclear PER phosphorylation dynamics in buffering circadian period against environmental temperature fluctuations.

neuroscience↗

bioRxiv2026

Core circadian clock genes control molecular and behavioral circatidal rhythms in Parhyale hawaiensis

Marine organisms exhibit 12.4-hour rhythms of gene expression, physiology and behavior synchronized by tidal cues. The mechanism underlying these circatidal rhythms, and its overlap with the circadian clockwork, has remained elusive. However, recent studies showed that the core circadian gene BMAL1 sustains circatidal behavior in crustaceans. Therefore, we mutagenized the other three core circadian clock genes (PhCry2, PhPer and PhClk) in P. hawaiensis, a marine amphipod. We found that they are necessary for both circadian and circatidal behaviors. Moreover, all four core circadian genes are critical for 24-h oscillations of mRNA levels in circadian brain neurons and 12.4-h mRNA rhythms in circatidal neurons. Unexpectedly, the mutants indicate that PhCLK represses PhPer expression independently of PhBMAL1 specifically in circatidal neurons. Our study thus reveals that circadian and circatidal clocks share four core molecular components, but their transcriptional wiring differs.

neuroscience↗

bioRxiv2026

Time in shells: Complex interaction between biological clock and biomineralisation in Mytilus galloprovincialis

The growth of bivalve shells is neither homogeneous nor continuous in time, resulting in the formation of growth patterns that correspond to the alternation of growth lines and increments deposited at regular intervals of time. The control of periodic increment formation is poorly understood and several hypotheses have been proposed. It has been proposed that environmental factors directly impact shell growth patterns, although it occasionally fails to adequately explain the observed shell growth patterns. The present study investigates the alternative hypothesis that the process of shell biomineralisation is controlled by biological clocks. This study demonstrates the existence of a functional circadian clock in M. galloprovincialis, as evidenced by molecular and behavioural results. Core circadian clock genes and biomineralisation genes have been observed to be expressed in the same cells of the mantle as revealed by in situ hybridisation experiments. However, the expression of core circadian clock genes and biomineralisation genes tested in situ and in aquaria exhibited different rhythmic profiles. This finding suggests that the clock does not directly activate the expression of the targeted biomineralisation genes in the mantle. Nevertheless, a significant rhythm of expression of biomineralisation-related genes was observed in mussels reared under free-running conditions, revealing the endogenous nature of the rhythm. The present study suggests that biological clocks play a role in controlling shell biomineralisation in M. galloprovincialis, although the precise underlying mechanism remains to be elucidated.

physiology↗