title: RNA interference of the clock gene period disrupts circadian rhythms in the cricket Gryllus bimaculatus.
abstract: Periodic expression of so-called clock genes is an essential part of the circadian clock. In Drosophila melanogaster the cyclic expression of per and tim through an autoregulatory feedback loop is believed to play a central role in circadian rhythm generation. However, it is still elusive whether this hypothesis is applicable to other insect species. Here it is shown that per gene plays a key role in the rhythm generation in the cricket Gryllus bimaculatus. Measurement of per mRNA levels in the optic lobe revealed the rhythmic expression of per in light cycles with a peak in the late day to early night, persisting in constant darkness. A single injection of per double-stranded RNA (dsRNA) into the abdomen of the final instar nymphs effectively knocked down the mRNA levels as adult to about 50% of control animals. Most of the per dsRNA-injected crickets completely lost the circadian locomotor activity rhythm in constant darkness up to 50 days after the injection, whereas those injected with DsRed2 dsRNA as a negative control clearly maintained it. The electrical activity of optic lobe efferents also became arrhythmic in the per dsRNA-injected crickets. These results not only suggest that per plays an important role in the circadian rhythm generation also in the cricket but also show that RNA interference is a powerful tool to dissect the molecular machinery of the cricket circadian clock.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Moriyama
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Svetlana G
authors.initials: SG
authors.lastname: Karpova
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Sumihare
authors.initials: S
authors.lastname: Noji
authors.forename: Kenji
authors.initials: K
authors.lastname: Tomioka
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000235:genetics*; D056926:CLOCK Proteins; D002940:Circadian Rhythm / Q000235:genetics*; D017344:Genes, Insect; D006135:Gryllidae / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000032:analysis; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D015534:Trans-Activators; D056926:CLOCK Proteins