title: cryptochromegenes form an oscillatory loop independent of theper/timloop in the circadian clockwork of the cricketGryllus bimaculatus.
abstract: BACKGROUND
  Animals exhibit circadian rhythms with a period of approximately 24 h in various physiological functions, including locomotor activity. This rhythm is controlled by an endogenous oscillatory mechanism, or circadian clock, which consists of cyclically expressed clock genes and their product proteins.cryptochrome(cry) genes are thought to be involved in the clock mechanism, and their functions have been examined extensively in holometabolous insects, but in hemimetabolous insects their role is less well understood.
  
  
  RESULTS
  In the present study, the role ofcrygenes was investigated using RNAi technology in a hemimetabolous insect, the cricketGryllus bimaculatus. Using a molecular cloning approach, we obtained cDNAs for twocrygenes:Drosophila-typecry1(Gb'cry1) and mammalian-typecry2(Gb'cry2).Gb'cry2has six splicing variants, most of which showed rhythmic mRNA expression.Gb'cry1RNAitreatment had only a limited effect at the behavioral and molecular levels, whileGb'cry2RNAihad a significant effect on behavioral rhythms and molecular oscillatory machinery, alone or in combination withGb'cry1RNAi. InGb'cry1/Gb'cry2double-RNAi crickets, most clock genes showed arrhythmic expression, except fortimeless, which retained clear rhythmic expression. Molecular analysis revealed that some combination ofGb'cry1andGb'cry2variants suppressed CLK/CYC transcriptional activity in cultured cells.
  
  
  CONCLUSIONS
  Based on these results, we propose a new model of the cricket's circadian clock, including a molecular oscillatory loop forGb'cry2, which can operate independent of theGb'per/Gb'timloop.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530 Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tokuoka
authors.affiliation: Graduate School of Science, Kyushu University, Fukuoka, 819-0395 Japan.
authors.forename: Taichi Q
authors.initials: TQ
authors.lastname: Itoh
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530 Japan.
authors.forename: Shinryo
authors.initials: S
authors.lastname: Hori
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530 Japan.
authors.forename: Outa
authors.initials: O
authors.lastname: Uryu
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530 Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Danbara
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530 Japan.
authors.forename: Motoki
authors.initials: M
authors.lastname: Nose
authors.affiliation: Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Bando
authors.affiliation: Graduate School of Science, Kyushu University, Fukuoka, 819-0395 Japan.
authors.forename: Teiichi
authors.initials: T
authors.lastname: Tanimura
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530 Japan.
authors.forename: Kenji
authors.identifier: 0000-0001-7951-8950
authors.initials: K
authors.lastname: Tomioka
keywords: Circadian clock; Clock gene; Cryptochrome; Insect; Molecular oscillatory mechanism