AUTHOR=Homma Satoshi , Murata Akihisa , Ikegami Masato , Kobayashi Masakazu , Yamazaki Maki , Ikeda Kento , Daimon Takaaki , Numata Hideharu , Mizoguchi Akira , Shiomi Kunihiro 

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

JOURNAL=Frontiers in Physiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.863380

DOI=10.3389/fphys.2022.863380

ISSN=1664-042X

ABSTRACT=<p>The bivoltine strain of the domestic silkworm, <italic>Bombyx mori</italic>, 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 <italic>period</italic> (<italic>per</italic>) in circadian rhythms and photoperiod-induced diapause, the roles of other core feedback loop genes, including <italic>timeless</italic> (<italic>tim</italic>), <italic>Clock</italic> (<italic>Clk</italic>), <italic>cycle</italic> (<italic>cyc</italic>), and <italic>cryptochrome2</italic> (<italic>cry2</italic>), 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, <italic>per</italic>, <italic>tim</italic>, <italic>Clk</italic>, <italic>cyc</italic>, and <italic>cry2</italic> knockout (KO) mutants were generated, and the percentages of diapause and non-diapause eggs were determined. The results show that <italic>per</italic>, <italic>tim</italic>, <italic>Clk</italic>, <italic>cyc</italic>, and <italic>cry2</italic> 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 (<italic>wt</italic>) 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.</p>