Molecular Mechanism of the Circadian Clock

Doležel, David

doi:10.1007/978-981-99-0726-7_4

Cited by 6 publications

(3 citation statements)

References 217 publications

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“…It will be interesting to see whether TAI participates in the Drosophila circadian clock. Although the circadian clock is generally well conserved in insects [ 59 , 60 ], there are several noteworthy unique features of Drosophila clock machinery: For example, the transactivation domain (TAD) is localized only to CLK in the fruit fly, whereas CYC does not have this domain. The same pattern is found only in Cyclorrhapha (a subgroup of Diptera), whereas the TAD is localized to CYC/BMAL1 in the other bilaterians (Bilateria, most animals except sponges, placozoans, cnidarians, and ctenophores).…”

Section: Discussionmentioning

confidence: 99%

Steroid receptor coactivator TAIMAN is a new modulator of insect circadian clock

Smykal,

Chodakova,

Hejnikova

et al. 2023

PLoS Genet

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TAIMAN (TAI), the only insect ortholog of mammalian Steroid Receptor Coactivators (SRCs), is a critical modulator of ecdysone and juvenile hormone (JH) signaling pathways, which govern insect development and reproduction. The modulatory effect is mediated by JH-dependent TAI’s heterodimerization with JH receptor Methoprene-tolerant and association with the Ecdysone Receptor complex. Insect hormones regulate insect physiology and development in concert with abiotic cues, such as photo- and thermoperiod. Here we tested the effects of JH and ecdysone signaling on the circadian clock by a combination of microsurgical operations, application of hormones and hormone mimics, and gene knockdowns in the linden bug Pyrrhocoris apterus males. Silencing taiman by each of three non-overlapping double-strand RNA fragments dramatically slowed the free-running period (FRP) to 27–29 hours, contrasting to 24 hours in controls. To further corroborate TAIMAN’s clock modulatory function in the insect circadian clock, we performed taiman knockdown in the cockroach Blattella germanica. Although Blattella and Pyrrhocoris lineages separated ~380 mya, B. germanica taiman silencing slowed the FRP by more than 2 hours, suggesting a conserved TAI clock function in (at least) some insect groups. Interestingly, the pace of the linden bug circadian clock was neither changed by blocking JH and ecdysone synthesis, by application of the hormones or their mimics nor by the knockdown of corresponding hormone receptors. Our results promote TAI as a new circadian clock modulator, a role described for the first time in insects. We speculate that TAI participation in the clock is congruent with the mammalian SRC-2 role in orchestrating metabolism and circadian rhythms, and that TAI/SRCs might be conserved components of the circadian clock in animals.

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Section: Discussionmentioning

confidence: 99%

Steroid receptor coactivator TAIMAN is a new modulator of insect circadian clock

Smykal,

Chodakova,

Hejnikova

et al. 2023

PLoS Genet

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“…Circadian clocks operate similarly across different taxa. Their cellular mechanism is comprised of transcription-translation feedback loops of clock genes and their protein products, capable of producing self-sustained circadian oscillations (Doležel, 2023; Helfrich-Förster, 2004). Detailed knowledge about the molecular mechanisms of animal clocks is available mainly from the studies in mouse and fruit fly as representatives of mammals and insects, respectively.…”

Section: Introductionmentioning

confidence: 99%

Deciphering a beetle clock: individual and sex-dependent variation in daily activity patterns

Prüser,

Schulz

et al. 2024

Preprint

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Circadian clocks are inherent to most organisms, including cryptozoic animals that seldom encounter direct light, and regulate their daily activity cycles. A conserved suite of clock genes underpins these rhythms. In this study, we explore the circadian behaviors of the red flour beetleTribolium castaneum, a significant pest impacting stored grain globally. We report on how daily light and temperature cues synchronize distinct activity patterns in these beetles, characterized by reduced morning activity and increased evening activity, anticipating the respective environmental transitions. Although less robust, rhythmicity in locomotor activity is maintained in constant dark and constant light conditions. Notably, we observed more robust rhythmic behaviors in males than females with individual variations exceeding those previously reported for other insect species. RNA interference targeting theClockgene disrupted locomotor activity rhythms. Our findings demonstrate the existence of a circadian clock and of clock-controlled behaviors inT. castaneum. Furthermore, they highlight substantial individual differences in circadian activity, laying the groundwork for future research on the relevance of individual variation in circadian rhythms in an ecological and evolutionary context.

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“…They have been studied in many multicellular organisms but are also known from unicellular eukaryotes and prokaryotes (Huang et al, 1990). In some model organisms, such as Arabidopsis thaliana, Neurospora crassa, Mus musculus, Drosophila melanogaster, and Synechococcus, the components and mechanism of circadian clocks are known in great detail (Kondo and Ishiura, 2000;Baker et al, 2012;Mohawk et al, 2012;Nakamichi, 2020;Dolezěl, 2023), while in others, the system is just being described (Poliner et al, 2019;Farre, 2020;Borges-Pereira et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Circadian rhythms and circadian clock gene homologs of complex alga Chromera velia

Richtová,

Bazalová,

Horák

et al. 2023

Front. Plant Sci.

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Most organisms on Earth are affected by periodic changes in their environment. The circadian clock is an endogenous device that synchronizes behavior, physiology, or biochemical processes to an approximately 24-hour cycle, allowing organisms to anticipate the periodic changes of day and night. Although circadian clocks are widespread in organisms, the actual molecular components differ remarkably among the clocks of plants, animals, fungi, and prokaryotes. Chromera velia is the closest known photosynthetic relative of apicomplexan parasites. Formation of its motile stage, zoospores, has been described as associated with the light part of the day. We examined the effects on the periodic release of the zoospores under different light conditions and investigated the influence of the spectral composition on zoosporogenesis. We performed a genomic search for homologs of known circadian clock genes. Our results demonstrate the presence of an almost 24-hour free-running cycle of zoosporogenesis. We also identified the blue light spectra as the essential compound for zoosporogenesis. Further, we developed a new and effective method for zoospore separation from the culture and estimated the average motility speed and lifespan of the C. velia zoospores. Our genomic search identified six cryptochrome-like genes, two genes possibly related to Arabidopsis thaliana CCA/LHY, whereas no homolog of an animal, cyanobacterial, or fungal circadian clock gene was found. Our results suggest that C. velia has a functional circadian clock, probably based mainly on a yet undefined mechanism.

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Molecular Mechanism of the Circadian Clock

Cited by 6 publications

References 217 publications

Steroid receptor coactivator TAIMAN is a new modulator of insect circadian clock

Steroid receptor coactivator TAIMAN is a new modulator of insect circadian clock

Deciphering a beetle clock: individual and sex-dependent variation in daily activity patterns

Circadian rhythms and circadian clock gene homologs of complex alga Chromera velia

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