title: Photic regulation of arylalkylamine N-acetyltransferase 1 mRNA in trout retina.
abstract: Melatonin production in the pineal organ and retina is controlled by both light-dark cycles and a circadian clock via the oscillating activity of arylalkylamine N-acetyltransferase (AANAT) in most vertebrates. However, this clock regulation is absent in the rainbow trout (Oncorhynchus mykiss) pineal organ: the trout has two different AANAT genes (AANAT1 and AANAT2), and AANAT2 mRNA levels in the pineal organ did not exhibit circadian oscillation In this study, we confirmed by RT-PCR analysis that AANAT1 is expressed only in the retina, while AANAT2 is expressed in the pineal organ and brain. Real-time quantitative PCR analysis demonstrated that AANAT1 mRNA levels in the retina exhibited daily variations with high levels during the dark phase under light-dark cycles, but kept high and low titers under constant darkness and constant light, respectively. Thus, AANAT1 gene expression in the trout retina is regulated not by a circadian clock but by lighting conditions.
authors.affiliation: Laboratory of Aquatic Animal Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mizusawa
authors.forename: M
authors.initials: M
authors.lastname: Iigo
authors.forename: T
authors.initials: T
authors.lastname: Masuda
authors.forename: K
authors.initials: K
authors.lastname: Aida
mesh_terms: D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000235:genetics*; D002940:Circadian Rhythm; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects*; D007527:Isoenzymes / Q000235:genetics; D017686:Oncorhynchus mykiss; D010775:Photic Stimulation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012160:Retina / Q000201:enzymology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000528:radiation effects*
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D001191:Arylamine N-Acetyltransferase