Persisting circadian rhythm of cell division in a photosynthetic mutant of Euglena.
A persisting, free-running, circadian rhythm of cell division in a heterotrophically grown mutant of Euglena gracilis var. bacillaris having impaired photosynthesis is obtained upon placing a culture that has been previously synchronized by a 10,14 light-dark cycle into continuous darkness at 19 degrees C (but not at 25 degrees C). A similar persisting rhythm is initiated in exponentially increasing cultures (growing in darkness at 19 degrees C) by a single "switch-up" in irradiance to continuous bright illumination. The results implicate an endogenous biological clock which "gates" the specific event of cell division in the cell developmental cycle.
D002455:Cell Division; D002940:Circadian Rhythm; D003624:Darkness; D005055:Euglena / Q000166:cytology* / Q000254:growth & development; D008027:Light; D009154:Mutation; D010788:Photosynthesis