Changes in the Productivity and Nuclear Divisions in Synchronous <italic>Chlorella</italic> and Circadian Rhythm

Abstract

Circadian rhythmic changes of cell production were found at the end of a test cycle (LD 14 : 10 h) and the synthetic tendencies during the test cycle were examined. The rates but not the duration of syntheses of chlorophyll, DNA and soluble protein rhythmically changed with additional waiting time in the dark after a growth cycle (LD 14 : 10). Changes in the rates of RNA and total protein synthesis were apparent only during the first 9 h in the light phase of the test cycle. However, the rate of carbohydrate synthesis during the test cycle was completely different; an exponential pattern was observed in cells with 0 and 24 h waiting times, but a sigmoid one in cells with 12 h waiting time. Nuclear divisions (into 16 or even more) followed DNA synthesis. Cells with 12 h waiting time remained longer in each multinuclear phase (demonstrated by the 2 and 8 states) and showed extremely lowered productivity (ca. 50% only).