title: Circadian G2 arrest as related to circadian gating of cell population growth in Euglena.
abstract: Cell population growth is gated to occur in particular circadian phases, which has been known for over four decades in various organisms including cyanobacteria and human. However, little is known as to which cell cycle phases from G1 to M are primarily regulated by the circadian rhythm or when in a circadian cycle this primary regulation takes place. We report here that in the flagellate alga Euglena gracilis grown photoautotrophically, the circadian rhythm primarily prevented developmentally matured G2 cells from progressing to mitosis, such that cell population growth occurred only during subjective night. In addition, we found that the circadian rhythm also arrests G1-to-S and S-to-G2 transitions at particular circadian phases.
authors.affiliation: Laboratory of Biological Rhythms, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, 080-8555 Japan.
authors.forename: Aoen
authors.initials: A
authors.lastname: Bolige
authors.forename: Shin-Ya
authors.initials: SY
authors.lastname: Hagiwara
authors.forename: Yulan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ken
authors.initials: K
authors.lastname: Goto
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002940:Circadian Rhythm; D004261:DNA Replication; D005056:Euglena gracilis / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D016195:G2 Phase; D008938:Mitosis; D017440:Photoperiod