The circadian rhythm as biological teaching material—Circadian rhythm of photoaccumulation in Paramecium bursaria—

Abstract

Population of Paramecium bursaria cells exhibits a circadian rhythm of photoaccumulation. The mean period of the rhythm is about 25.3 hours in LL at 25°C. In this experiment, the photoaccumulation rhythms of some strains of P. bursaria are measured automatically by using the microcomputer. The period of photoaccumulation rhythm in the strain of BG is about 22.2 hours, which is shorter than the mean level. The period of T316 is about 27.4 hours, which is longer than the mean level. The correlation between the period of mating reactivity rhythm of this strain, which was about 27.0 hours, is almost similar to that of photoaccumulation rhythm in the strain of T316, This result shows the possibility that there is an endgeneous circadian oscillator which controls both of two rhythms photoaccumulation and mating reactivity.