Is the cell division cycle gated by a circadian clock? The case of Chlamydomonas reinhardtii.
Circadian oscillators are known to regulate the timing of cell division in many organisms. In the case of Chlamydomonas reinhardtii, however, this conclusion has been challenged by several investigators. We have reexamined this issue and find that the division behavior of Chlamydomonas meets all the criteria for circadian rhythmicity: persistence of a cell division rhythm (a) with a period of approximately 24 h under free-running conditions, (b) that is temperature compensated, and (c) which can entrain to light/dark signals. In addition, a mutation that lengthens the circadian period of the phototactic rhythm similarly affects the cell division rhythm. We conclude that a circadian mechanism determines the timing of cell division in Chlamydomonas reinhardtii.
Goto
K
K
Department of Liberal Arts and Sciences, Obihiro University of Agriculture and Veterinary Medicine, Japan.
Johnson
C H
CH
D000818:Animals; D001683:Biological Clocks / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D002465:Cell Movement / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D003624:Darkness; D006358:Hot Temperature; D008027:Light; D008954:Models, Biological; D017440:Photoperiod; D012044:Regression Analysis; D013045:Species Specificity; D013997:Time Factors