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1. The period gene alters daily and seasonal timing in Ostrinia nubilalis

   https://doi.org/10.1101/2024.11.02.621642  

   Dayton, Jacob N; Dopman, Erik B (November 2024, bioRxiv)

   Summary The timing of insects’ daily (feeding, movement) and seasonal (diapause, migration) rhythms affects their population dynamics and distribution. Yet, despite their implications for insect conservation and pest management, the genetic mechanisms underlying variation in timing are poorly understood. Prior research in the European corn borer moth (Ostrinia nubilalis) associated ecotype differences in seasonal diapause and daily activity with genetic variation at the circadian clock geneperiod(per). Here, we demonstrate that populations with divergent allele frequencies atperexhibit differences in daily behavior, seasonal development, and the expression of circadian clock genes. Specifically, later daily activity and shortened diapause were associated with a reduction and delay in the abundance of cyclingpermRNA. CRISPR/Cas9-mediated mutagenesis revealed thatperand/or an intact circadian clock network were essential for the appropriate timing of daily behavior and seasonal responsiveness. Furthermore, a reduction ofpergene dosage inperheterozygous mutants (per^-/+) pleiotropically decreased the diapause incidence, shortened post-diapause development, and delayed the timing of daily behavior, in a manner phenotypically reminiscent of wild-type individuals. Altogether, this combination of observational and experimental research strongly suggests thatperis a master regulator of biological rhythms and may contribute to the observed life cycle differences between bivoltine (two generation) and univoltine (one generation)O. nubilalis. HighlightsNatural ecotypes with divergentperiod(per) genotypes differ in their daily and seasonal responses to photoperiodLater daily activity, reduced diapause incidence, and shorter post-diapause development is associated with reducedpermRNA abundanceperis essential for short-day recognition and daily timingReducedpergene dosage shortened post-diapause development and delayed locomotor activity 

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2. A high-quality, long-read genome assembly of the whitelined sphinx moth (Lepidoptera: Sphingidae: Hyles lineata ) shows highly conserved melanin synthesis pathway genes

   https://doi.org/10.1093/g3journal/jkad090  

   Godfrey, R Keating; Britton, Sarah E; Mishra, Shova; Goldberg, Jay K; Kawahara, Akito Y (April 2023, G3 Genes, Genomes, Genetics)

   Vogel, K (Ed.)

   Abstract The sphinx moth genus Hyles comprises 29 described species inhabiting all continents except Antarctica. The genus diverged relatively recently (40–25 MYA), arising in the Americas and rapidly establishing a cosmopolitan distribution. The whitelined sphinx moth, Hyles lineata, represents the oldest extant lineage of this group and is one of the most widespread and abundant sphinx moths in North America. Hyles lineata exhibits the large body size and adept flight control characteristic of the sphinx moth family (Sphingidae), but it is unique in displaying extreme larval color variation and broad host plant use. These traits, in combination with its broad distribution and high relative abundance within its range, have made H. lineata a model organism for studying phenotypic plasticity, plant–herbivore interactions, physiological ecology, and flight control. Despite being one of the most well-studied sphinx moths, little data exist on genetic variation or regulation of gene expression. Here, we report a high-quality genome showing high contiguity (N50 of 14.2 Mb) and completeness (98.2% of Lepidoptera BUSCO genes), an important first characterization to facilitate such studies. We also annotate the core melanin synthesis pathway genes and confirm that they have high sequence conservation with other moths and are most similar to those of another, well-characterized sphinx moth, the tobacco hornworm (Manduca sexta). 

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

   https://doi.org/10.64898/2026.02.27.708297  

   Louis, Victoria; Bellido, Zachary; Helfenbein, Adam; Rosenthal, Joshua; Emery, Patrick (March 2026, bioRxiv)

   Abstract 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, PhPerandPhClk) inP. 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 repressesPhPerexpression 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. 

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4. Light pollution disrupts circadian clock gene expression in two mosquito vectors during their overwintering dormancy

   https://doi.org/10.1038/s41598-024-52794-x  

   Fyie, Lydia R; Westby, Katie M; Meuti, Megan E (December 2024, Scientific Reports)

   Abstract Artificial light at night (ALAN) is an increasingly important form of environmental disturbance as it alters Light:Dark cycles that regulate daily and seasonal changes in physiology and phenology. The Northern house mosquito (Culex pipiens) and the tiger mosquito (Aedes albopictus) enter an overwintering dormancy known as diapause that is cued by short days. These two species differ in diapause strategy:Cx. pipiensdiapause as adult females whileAe. albopictusenter a maternally-programmed, egg diapause. Previous studies found that ALAN inhibits diapause in both species, but the mechanism is unknown. As the circadian clock is implicated in the regulation of diapause in many insects, we examined whether exposure to ALAN altered the daily expression of core circadian cloc genes (cycle,Clock,period,timeless,cryptochrome 1,cryptochrome 2, andPar domain protein 1) in these two species when reared under short-day, diapause-inducing conditions. We found that exposure to ALAN altered the abundance of several clock genes in adult females of both species, but that clock gene rhythmicity was maintained for most genes. ALAN also had little effect on clock gene abundance in mature oocytes that were dissected from femaleAe. albopictusthat were reared under short day conditions. Our findings indicate that ALAN may inhibit diapause initiation through the circadian clock in two medically-important mosquitoes. 

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5. Robustness of gene expression rhythmicity can identify new oscillator components in the circadian clock

   https://doi.org/10.1093/jxb/eraf139  

   Bonnot, Titouan; Cairo, Desmond; Nagel, Dawn H (April 2025, Journal of Experimental Botany)

   Penfield, Steve (Ed.)

   Abstract The transcriptomes of many eukaryotic genomes exhibit rhythmic gene expression, resulting in genes that show peak expression at specific times of the day. In plants, genes that are considered to be oscillator components alter the circadian period and/or phase (time of peak expression) when misexpressed. The first plant circadian clock gene was identified almost 30 years ago, and since then additional components have been identified through forward and reverse genetic mutant screens. Over the years, mathematical modeling has helped to refine our understanding of oscillator interactions within the network and in the context of environmental cues. The complexity of the clock network suggests that additional components are yet to be discovered. In the era of genomics and genome-scale analysis, circadian research has focused on understanding the mechanisms of clock gene control of cellular and physiological output processes, often in the context of environmental stimuli. Transcriptome studies with temporal and/or spatial resolution are increasingly being carried out and the resulting comprehensive datasets can be mined to predict new oscillator components. Most clock genes show stronger oscillatory expression patterns compared to other genes in the genome. By selecting from transcriptome data genes that are significantly and robustly rhythmic, putative clock genes can be identified and characterized. 

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