Genome-wide analysis of the diatom cell cycle unveils a novel type of cyclins involved in environmental signaling.
BACKGROUND
Despite the enormous importance of diatoms in aquatic ecosystems and their broad industrial potential, little is known about their life cycle control. Diatoms typically inhabit rapidly changing and unstable environments, suggesting that cell cycle regulation in diatoms must have evolved to adequately integrate various environmental signals. The recent genome sequencing of Thalassiosira pseudonana and Phaeodactylum tricornutum allows us to explore the molecular conservation of cell cycle regulation in diatoms.


RESULTS
By profile-based annotation of cell cycle genes, counterparts of conserved as well as new regulators were identified in T. pseudonana and P. tricornutum. In particular, the cyclin gene family was found to be expanded extensively compared to that of other eukaryotes and a novel type of cyclins was discovered, the diatom-specific cyclins. We established a synchronization method for P. tricornutum that enabled assignment of the different annotated genes to specific cell cycle phase transitions. The diatom-specific cyclins are predominantly expressed at the G1-to-S transition and some respond to phosphate availability, hinting at a role in connecting cell division to environmental stimuli.


CONCLUSIONS
The discovery of highly conserved and new cell cycle regulators suggests the evolution of unique control mechanisms for diatom cell division, probably contributing to their ability to adapt and survive under highly fluctuating environmental conditions.
Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Gent, Belgium.
Marie J J
MJ
Huysman
Cindy
C
Martens
Klaas
K
Vandepoele
Jeroen
J
Gillard
Edda
E
Rayko
Marc
M
Heijde
Chris
C
Bowler
Dirk
D
Inzé
Yves
Y
Van de Peer
Lieven
L
De Veylder
Wim
W
Vyverman
D002453:Cell Cycle / Q000235:genetics*; D016213:Cyclins / Q000235:genetics*; D017377:Diatoms / Q000145:classification / Q000235:genetics*; D005786:Gene Expression Regulation; D016678:Genome; D055106:Genome-Wide Association Study; D010710:Phosphates / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*
D016213:Cyclins; D010710:Phosphates