The Chlamydomonas cell cycle is regulated by a light/dark-responsive cell-cycle switch

摘要: Cultures of the unicellular green alga Chlamydomonas reinhardii can be synchronized by light/dark cycling not only under photoautotrophic but also mixotrophic growth conditions. We observed that cultures in presence acetate continue to divide synchronously for one cell-cycle period when transferred heterotrophic This finding enabled us investigate differential effects light on cell and division. When cells were exposed continuous at beginning they entered division phase earlier than dark-grown as a consequence an increased rate. Illumination end period, however, caused considerable delay extended period. The light-induced was 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea (DCMU), inhibitor photosystem II. demonstrates is directly influenced light/dard-responsive switch rather light/dark-dependent changes energy metabolism. importance this control regulation cycle investigated comparison with other mechanisms (size control, time control). found regulates transition from G1-to S-phase. mechanism effective which have attained commitment least round DNA replication maximal mass initiates light.