title: Lunar phase-dependent expression of cryptochrome and a photoperiodic mechanism for lunar phase-recognition in a reef fish, goldlined spinefoot.
abstract: Lunar cycle-associated physiology has been found in a wide variety of organisms. Recent study has revealed that mRNA levels of Cryptochrome (Cry), one of the circadian clock genes, were significantly higher on a full moon night than on a new moon night in coral, implying the involvement of a photoreception system in the lunar-synchronized spawning. To better establish the generalities surrounding such a mechanism and explore the underlying molecular mechanism, we focused on the relationship between lunar phase, Cry gene expression, and the spawning behavior in a lunar-synchronized spawner, the goldlined spinefoot (Siganus guttatus), and we identified two kinds of Cry genes in this animal. Their mRNA levels showed lunar cycle-dependent expression in the medial part of the brain (mesencephalon and diencephalon) peaking at the first quarter moon. Since this lunar phase coincided with the reproductive phase of the goldlined spinefoot, Cry gene expression was considered a state variable in the lunar phase recognition system. Based on the expression profiles of SgCrys together with the moonlight's pattern of timing and duration during its nightly lunar cycle, we have further speculated on a model of lunar phase recognition for reproductive control in the goldlined spinefoot, which integrates both moonlight and circadian signals in a manner similar to photoperiodic response.
authors.affiliation: Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Fukushiro
authors.forename: Takahiro
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Sung-Pyo
authors.initials: SP
authors.lastname: Hur
authors.forename: Nozomi
authors.initials: N
authors.lastname: Sugama
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takemura
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kubo
authors.forename: Keiko
authors.initials: K
authors.lastname: Okano
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Okano
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002940:Circadian Rhythm; D003001:Cloning, Molecular; D056931:Cryptochromes / Q000737:chemistry* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005399:Fishes / Q000502:physiology*; D008027:Light; D016081:Moon; D010053:Ovary / Q000378:metabolism; D017440:Photoperiod; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D056931:Cryptochromes; D017931:DNA Primers; D012333:RNA, Messenger