Yoshiyuki Moriyama
   Department   Kawasaki Medical School  Kawasaki Medical School, Department of Natural Sciences,
   Position   Assistant Professor
Article types 原著
Language English
Peer review Peer reviewed
Title A novel photic entrainment mechanism for the circadian clock in an insect: involvement of c-fos and cryptochromes
Journal Formal name:Zoological Letters
Abbreviation:Zoological Lett.
Domestic / ForeginForegin
Volume, Issue, Page 4
Author and coauthor Yuki Kutaragi, Atsushi Tokuoka, Yasuaki Tomiyama, Motoki Nose, Takayuki Watanabe, Tetsuya Bando, Yoshiyuki Moriyama, Kenji Tomioka
Publication date 2018/09
Entrainment to the environmental light cycle is an essential property of the circadian clock. Although the compound eye is known to be the major photoreceptor necessary for entrainment in many insects, the molecular mechanisms of photic entrainment remain to be explored.

We found that cryptochromes (crys) and c-fos mediate photic entrainment of the circadian clock in a hemimetabolous insect, the cricket Gryllus bimaculatus. We examined the effects of RNA interference (RNAi)-mediated knockdown of the cry genes, Gb'cry1 and Gb'cry2, on photic entrainment, and light-induced resetting of the circadian locomotor rhythm. Gb'cry2 RNAi accelerated entrainment for delay shifts, while Gb'cry1/ Gb'cry2 double RNAi resulted in significant lengthening of transient cycles in both advance and delay shifts, and even in entrainment failure in some crickets. Double RNAi also strongly suppressed light induced resetting. The Gb'cry-mediated phase shift or resetting of the rhythm was preceded by light-induced Gb'c-fosB expression. We also found that Gb'c-fosB, Gb'cry2 and Gb'period (Gb'per) were likely co-expressed in some optic lobe neurons.

Based on these results, we propose a novel model for photic entrainment of the insect circadian clock, which relies on the light information perceived by the compound eye.
DOI 10.1186/s40851-018-0109-8
PMID 30250749