Involvement of the Clock Gene Period in the Photoperiodism of the Silkmoth Bombyx mori

Ikeda, Kento; Daimon, Takaaki; Shiomi, Kunihiro; Udaka, Hiroko; Numata, Hideharu

doi:10.2108/zs210081

Cited by 24 publications

(33 citation statements)

References 53 publications

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“…The present study’s findings indicate that the clock genes per , tim , Clk , cyc , and cry2 are involved in temperature-dependent diapause induction. Involvement of clock genes in photoperiodic induction of diapause has been shown in various insects, including B. mori (e.g., Pavelka et al, 2003 ; Sakamoto et al, 2009 ; Ikeno et al, 2010 ; Merlin et al, 2013 ; Meuti et al, 2015 ; Cui et al, 2021 ; Ikeda et al, 2021 ). However, the role of clock genes in temperature-dependent diapause induction has not been shown.…”

Section: Discussionmentioning

confidence: 99%

“…KO mutants of per ( per +13 ) and BmoTRPA1 ( ∆TRPA1_1,429 ) were constructed following previously described procedures ( Ikeda et al, 2021 ; Yokoyama et al, 2021 ). The transcription activator-like effector nuclease (TALEN)-based mutant lines of five genes ( tim , Clk , cyc , cry1 , and cry2 ) were constructed according to previous methods ( Takasu et al, 2014 ; Yokoyama et al, 2021 ).…”

Section: Methodsmentioning

confidence: 99%

“…The expression of per , tim , Clk, cry1 , and cry2 exhibits temporal changes during embryonic development under both light/dark and DD conditions ( Tao et al, 2017 ; Ikeda et al, 2019 ; Nartey et al, 2021 ). Additionally, core clock gene mutations disrupt not only the daily rhythm in both egg-hatching and adult eclosion rhythms in each per and tim knockout (KO; Ikeda et al, 2019 ; Nartey et al, 2021 ) but also the photoperiodic diapause, as a specific subtype of dormancy disrupted in per KO ( Ikeda et al, 2021 ). Overall, research findings suggest that these clock genes operate as components of the core feedback loop module in the circadian clock of B. mori .…”

Section: Introductionmentioning

confidence: 99%

“…When eggs are incubated at 25°C under continuous darkness (25DD), the resultant female moths lay nearly 100% diapause eggs. In contrast, incubation of eggs at 15°C under dark conditions (15DD) resulted in moths that laid nearly 100% non-diapause eggs, although photoperiodic conditions during larval stages affected diapause determination when eggs were incubated at 20°C under continuous light ( Ikeda et al, 2021 ). Thus, Kosetsu is considered a typical strain that is susceptible to temperature-dependent diapause induction.…”

Section: Introductionmentioning

confidence: 99%

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Circadian Clock Genes Regulate Temperature-Dependent Diapause Induction in Silkworm Bombyx mori

Homma

Murata²,

Ikegami³

et al. 2022

Front. Physiol.

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The bivoltine strain of the domestic silkworm, Bombyx mori, exhibits a facultative diapause phenotype that is determined by maternal environmental conditions during embryonic and larval development. Although a recent study implicated a circadian clock gene period (per) in circadian rhythms and photoperiod-induced diapause, the roles of other core feedback loop genes, including timeless (tim), Clock (Clk), cycle (cyc), and cryptochrome2 (cry2), have to be clarified yet. Therefore, the aim of this study was to elucidate the roles of circadian clock genes in temperature-dependent diapause induction. To achieve this, per, tim, Clk, cyc, and cry2 knockout (KO) mutants were generated, and the percentages of diapause and non-diapause eggs were determined. The results show that per, tim, Clk, cyc, and cry2 regulated temperature-induced diapause by acting upstream of cerebral γ-aminobutyric acid (GABA)ergic and diapause hormone signaling pathways. Moreover, the temporal expression of the clock genes in wild-type (wt) silkworms was significantly different from that of thermosensitive transient receptor potential ankyrin 1 (TRPA1) KO mutants during embryonic development. Overall, the findings of this study provide target genes for regulating temperature-dependent diapause induction in silkworms.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Circadian Clock Genes Regulate Temperature-Dependent Diapause Induction in Silkworm Bombyx mori

Homma

Murata²,

Ikegami³

et al. 2022

Front. Physiol.

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“…Both mutants lost eclosion and hatching rhythms, indicating that core clock genes are indispensable for circadian rhythms in B. mori . In addition, two groups independently described per’s involvement in photoperiodic diapause induction (Cui et al, 2021; Ikeda et al, 2021). Ikeda et al demonstrated that per knockout in the Kosetsu strain abolishes photoperiod sensitivity during the larval stage and inhibits diapause egg production.…”

Section: Introductionmentioning

confidence: 99%

Knockouts of positive and negative elements of the circadian clock disrupt photoperiodic diapause induction in the silkworm,Bombyx mori

Tobita

Kiuchi

2022

Preprint

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Diapause is one of the most important traits that have sustained insects to thrive. Insects can prospectively arrest their development and increase environmental stress-resistance by entering diapause. The photoperiod is the signal that indicates insects the proper timing to enter diapause. Circadian clock genes are shown to be involved in photoperiodic diapause induction in various insect species. The silkworm, Bombyx mori, enters diapause at the embryonic stage. In bivoltine strains, diapause determination is affected by embryonic temperature and photoperiodic conditions during embryonic and larval stages. Two independent studies showed that knocking out the core clock gene, period, perturb photoperiodic diapause induction. However, whether the circadian clock as whole or individual clock genes are responsible for the photoperiodic diapause induction remains unknown. In this study, using CRISPR/Cas9 we knocked out negative (period and timeless) and positive elements (Clock and cycle) in p50T, a bivoltine strain which exhibits photoperiodic diapause induction during both embryonic and larval stages. The temporal expression patterns of clock genes changed in each core clock gene knockout strain, suggesting disruption of normal feedback loops produced by circadian clock genes. Furthermore, photoperiodic diapause induction during both embryonic and larval stages was lost in all knockout strains. Our results indicate the involvement of circadian clock in photoperiodic diapause induction in B. mori.HighlightsWe established knockout Bombyx mori strains of four core clock genesThe temporal expression patterns of clock genes changed in knockout strainsPhotoperiodic diapause induction was not observed in any knockout strainsGraphical abstract

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The clock gene Cryptochrome 1 is involved in the photoresponse of embryonic hatching behavior in Bombyx mori

Yuan

Luo

Zhao

et al. 2023

Arch Insect Biochem Physiol

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The hatching of insect eggs is a classic circadian behavior rhythm controlled by the biological clock. Its function is considered to impose a daily rhythm on the embryo, allowing it to hatch within a permissible time window. However, the molecular pathways through which the clock affects embryonic hatching behavior remain unclear. Here, we utilized a clock gene Cryptochrome1 (Cry1) knockout mutant to dissect the pathways by which the circadian clock affects embryonic hatching rhythm in the silkworm. In the Cry1 mutant, the embryo hatching rhythm was disrupted. Under the constant light or constant dark incubation conditions, mutant embryos lost their hatching rhythm, while wild‐type embryos hatch exhibiting free‐running rhythm. In the light‐dark cycle (LD), the hatching rhythm of CRY1‐deficient silkworms could not be entrained by the LD photoperiod during the incubation period. The messenger RNA levels and enzymatic activities of Cht and Hel in the mutant embryos were significantly reduced at circadian time 24 (CT24). Transcriptome analysis revealed significant differences in gene expression at CT24 between the Cry1 knockout mutant and the wild‐type, with 2616 differentially expressed genes identified. The enriched Gene Ontology pathway includes enzyme activity, energy availability, and protein translation. Short neuropeptide F signaling was reduced in the CT24 embryonic brain of the mutant, the expression of the neuropeptide PTTH was also reduced and the rhythm was lost, which further affects ecdysteroid signaling. Our results suggested that the silkworm circadian clock affects neuropeptide‐hormone signaling as well as physiological functions related to hatching, which may regulate the hatching rhythm.

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Involvement of the Clock Gene Period in the Photoperiodism of the Silkmoth Bombyx mori

Cited by 24 publications

References 53 publications

Circadian Clock Genes Regulate Temperature-Dependent Diapause Induction in Silkworm Bombyx mori

Circadian Clock Genes Regulate Temperature-Dependent Diapause Induction in Silkworm Bombyx mori

Knockouts of positive and negative elements of the circadian clock disrupt photoperiodic diapause induction in the silkworm,Bombyx mori

The clock gene Cryptochrome 1 is involved in the photoresponse of embryonic hatching behavior in Bombyx mori

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