At cellular level

Abstract

Abstract Our laboratory has previously demonstrated (Edmunds, 1971) that cell synchrony in a population of autotrophically batch‐cultured Euglena Gracilis Klebs (strain Z) can be entrained by a variety of light/dark cycles (e.g., L/D: 10/14) and temperature cycles (e.g., 18° /25° C) and that this rhythm will persist for as long as 10 days under constant illumination (800 lux) and temperature (25°C) as a low‐amplitude circadian rhythm with 10–20% of the cells dividing each cycle. We have also shown that a UV‐induced, heterotrophically‐grown, photosynthetic mutant (P4ZUL) of Euglena can be similarly entrained by L/D cycles or by single D/L transitions during the circadian‐infradian growth phase (G.T. > 24 hr) and that this rhythm persists for at least 6 days in D/D or bright L/L before it “damps out”; due to the onset of the stationary growth phase. Furthermore, long‐term persistence (2 month or longer) of the previously entrained division rhythm is observed in D/D at 19°C when the mutant is cultured semi‐c...