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1. Differential clock comparisons with a multiplexed optical lattice clock

   https://doi.org/10.1038/s41586-021-04344-y  

   Zheng, Xin; Dolde, Jonathan; Lochab, Varun; Merriman, Brett N.; Li, Haoran; Kolkowitz, Shimon (February 2022, Nature)
2. Ultra Freezing Attacks and Clock Glitching of Clock Oscillator Circuits

   https://doi.org/10.1109/AsianHOST53231.2021.9699709  

   Durand, Jonathon; Abedin, Anisul; Szefer, Jakub (December 2021, Asian Hardware Oriented Security and Trust Symposium (AsianHOST))
3. Synaptic targets of circadian clock neurons influence core clock parameters

   https://doi.org/10.1126/sciadv.adw4666  

   Scholz-Carlson, Eva; Iyer, Aishwarya R; Nern, Aljoscha; Ewer, John; Fernandez, Maria P (September 2025, Science Advances)

   Neuronal connectivity in the circadian clock network is essential for robust endogenous timekeeping. In the Drosophila circadian clock network, the small ventral lateral neurons (sLNvs) serve as critical pacemakers. Peptidergic communication mediated by the neuropeptide Pigment Dispersing Factor (PDF), released by sLNvs, has been well characterized. In contrast, little is known about the role of the synaptic connections that sLNvs form with downstream neurons. Connectomic analyses revealed that the sLNvs form strong synaptic connections with previously uncharacterized neurons called superior lateral protocerebrum 316 (SLP316). Here, we show that silencing the synaptic output from the SLP316 neurons via tetanus toxin expression shortened the free-running period, whereas hyperexciting them by expressing the bacterial voltage-gated sodium channel resulted in period lengthening. Under light-dark cycles, silencing SLP316 neurons caused lower daytime activity and higher daytime sleep. Our results reveal that the main postsynaptic partners of key Drosophila pacemaker neurons are a nonclock neuronal cell type that regulates the timing of sleep and activity. 

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4. The Drosophila circadian clock gene cycle controls the development of clock neurons

   https://doi.org/10.1371/journal.pgen.1011441  

   Biondi, Grace; McCormick, Gina; Fernandez, Maria P (October 2024, PLOS Genetics)

   Ewer, John (Ed.)

   Daily behavioral and physiological rhythms are controlled by the brain’s circadian timekeeping system, a synchronized network of neurons that maintains endogenous molecular oscillations. These oscillations are based on transcriptional feedback loops of clock genes, which inDrosophilainclude the transcriptional activatorsClock (Clk)andcycle (cyc). While the mechanisms underlying this molecular clock are very well characterized, the roles that the core clock genes play in neuronal physiology and development are much less understood. TheDrosophilatimekeeping center is composed of ~150 clock neurons, among which the four small ventral lateral neurons (sLN_vs) are the most dominant pacemakers under constant conditions. Here, we show that downregulating the clock genecycspecifically in thePdf-expressing neurons leads to decreased fasciculation both in larval and adult brains. This effect is due to a developmental role ofcyc, as both knocking downcycor expressing a dominant negative form ofcycexclusively during development lead to defasciculation phenotypes in adult clock neurons.Clkdownregulation also leads to developmental effects on sLNv morphology. Our results reveal a non-circadian role forcyc, shedding light on the additional functions of circadian clock genes in the development of the nervous system. 

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5. Radium Ion Optical Clock

   https://doi.org/10.1103/PhysRevLett.128.033202  

   Holliman, C. A.; Fan, M.; Contractor, A.; Brewer, S. M.; Jayich, A. M. (January 2022, Physical Review Letters)