title: Drosophila cryb mutation reveals two circadian clocks that drive locomotor rhythm and have different responsiveness to light.
abstract: Cryptochrome (CRY) is a blue-light-absorbing protein involved in the photic entrainment of the circadian clock in Drosophila melanogaster. We have investigated the locomotor activity rhythms of flies carrying cryb mutant and revealed that they have two separate circadian oscillators with different responsiveness to light. When kept in constant light conditions, wild-type flies became arrhythmic, while cryb mutant flies exhibited free-running rhythms with two rhythmic components, one with a shorter and the other with a longer free-running period. The rhythm dissociation was dependent on the light intensities: the higher the light intensities, the greater the proportion of animals exhibiting the two oscillations. External photoreceptors including the compound eyes and the ocelli are the likely photoreceptors for the rhythm dissociation, since rhythm dissociation was prevented in so1;cryb and norpAP41;cryb double mutant flies. Immunohistochemical analysis demonstrated that the PERIOD expression rhythms in ventrally located lateral neurons (LNvs) occurred synchronously with the shorter period component, while those in the dorsally located per-expressing neurons showed PER expression most likely related to the longer period component, in addition to that synchronized to the LNvs. These results suggest that the Drosophila locomotor rhythms are driven by two separate per-dependent clocks, responding differentially to constant light.
authors.affiliation: Department of Physics, Faculty of Science, Yamaguchi University, 753-8512, Japan.
authors.forename: Taishi
authors.initials: T
authors.lastname: Yoshii
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Funada
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ibuki-Ishibashi
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Teiichi
authors.initials: T
authors.lastname: Tanimura
authors.forename: Kenji
authors.initials: K
authors.lastname: Tomioka
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001683:Biological Clocks / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D002940:Circadian Rhythm / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D056931:Cryptochromes; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008027:Light; D009043:Motor Activity / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D056950:Period Circadian Proteins; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled
chemical_list: D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila