title: Casein kinases I of the silkworm, Bombyx mori: their possible roles in circadian timing and developmental determination.
abstract: Doubletime (DBT), a homolog of casein kinase Iepsilon (CKIepsilon), is an essential circadian clock component and developmental regulator in Drosophila melanogaster. The authors cloned a dbt homolog from the silkworm, Bombyx mori(Bmdbt), and examined its spatial and temporal expression in comparison to a CKI[alpha] homolog (BmCKIalpha). Four Bmdbt splice variants and 2 BmCKIalpha splice variants were detected, and their expression patterns varied in different tissues. The level of Bmdbt transcript in the brain was constant under LD 12:12 while those of BmCKIalpha transcripts fluctuated with a decrease at ZT12. In situ hybridization showed presumably identical distribution of dbt, CKIalpha, and per transcripts in the putative clock neurons of the head ganglia, as well as in the retina, where CKI-and PER-like immunoreactivities were colocalized, suggesting a possible involvement of both CKIs in the B. mori circadian system. Signals were detected at 4 Ia(1) neurons in each dorsolateral protocerebrum, 6 to 8 cells in the pars intercerebralis, about 6 cells in the suboesophageal ganglion, 2 neurons in the frontal ganglion, and most of the photoreceptors. All these cells contained dbt, CKIalpha, and per antisense transcripts. The Northern analysis of dbtand CKIalpha transcripts at different developmental stages showed that both genes were expressed at relatively high levels during early embryogenesis and in the ovary. The levels of CKIalpha transcripts were also high in the late larval stages until the mid-fifth instar and then suddenly disappeared before larval-pupal ecdysis. In contrast, the transcriptional activity of both genes was low in diapausing eggs.
authors.affiliation: Division of Molecular Science, Graduate School of Science and Technology, Kobe University, Nada, Kobe, Japan.
authors.forename: Le Thi Dieu
authors.initials: le TD
authors.lastname: Trang
authors.forename: Hana
authors.initials: H
authors.lastname: Sehadova
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ichihara
authors.forename: Sachio
authors.initials: S
authors.lastname: Iwai
authors.forename: Kazuei
authors.initials: K
authors.lastname: Mita
authors.forename: Makio
authors.initials: M
authors.lastname: Takeda
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000502:physiology*; D001921:Brain / Q000201:enzymology; D048149:Casein Kinase 1 epsilon / Q000378:metabolism / Q000502:physiology*; D047389:Casein Kinase I / Q000737:chemistry / Q000502:physiology*; D002940:Circadian Rhythm; D029721:Drosophila Proteins / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D056950:Period Circadian Proteins; D012160:Retina / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
chemical_list: D029721:Drosophila Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; C113519:dco protein, Drosophila; D048149:Casein Kinase 1 epsilon; D047389:Casein Kinase I