title: Light-dependent regulation of cell division in Ostreococcus: evidence for a major transcriptional input.
abstract: Cell division often occurs at specific times of the day in animal and photosynthetic organisms. Studies in unicellular photosynthetic algae, such as Chlamydomonas or Euglena, have shown that the photoperiodic control of cell division is mediated through the circadian clock. However, the underlying mechanisms remain unknown. We have studied the molecular basis of light-dependent control of cell division in the unicellular green alga Ostreococcus. We found that cell division obeys a circadian oscillator in Ostreococcus. We provide evidence suggesting that the clock may, at least in part, regulate directly cell division independently of the metabolism. Combined microarray and quantitative real-time reverse transcription-polymerase chain reaction analysis of the main core cell cycle gene expression revealed an extensive transcriptional regulation of cell division by the photoperiod in Ostreococcus. Finally, transcription of the main core cell cycle genes, including cyclins and cyclin-dependent kinases, was shown to be under circadian control in Ostreococcus, suggesting that these genes are potential targets of the circadian clock in the control of cell division.
authors.affiliation: Unité Mixte de Recherche 7628 Centre National de la Recherche Scientifique, Université Paris VI, Laboratoire Arago, 66650 Banyuls sur Mer, France.
authors.forename: Mickael
authors.initials: M
authors.lastname: Moulager
authors.forename: Annabelle
authors.initials: A
authors.lastname: Monnier
authors.forename: Béline
authors.initials: B
authors.lastname: Jesson
authors.forename: Régis
authors.initials: R
authors.lastname: Bouvet
authors.forename: Jean
authors.initials: J
authors.lastname: Mosser
authors.forename: Christian
authors.initials: C
authors.lastname: Schwartz
authors.forename: Lionel
authors.initials: L
authors.lastname: Garnier
authors.forename: Florence
authors.initials: F
authors.lastname: Corellou
authors.forename: François-Yves
authors.initials: FY
authors.lastname: Bouget
mesh_terms: D002455:Cell Division / Q000502:physiology*; D000460:Chlorophyta / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005786:Gene Expression Regulation; D008027:Light; D017440:Photoperiod; D014158:Transcription, Genetic