Key points are not available for this paper at this time.
ABSTRACT Circadian rhythms are common in eukaryotes, but the several claimed cases in prokaryotes are all open to alternative interpretation. We report here a clearcut circadian rhythm in cell division in a marine Synechococcus sp. strain WH7803, under conditions where the generation time is longer than one day, that is entrained by a light–dark cycle, and that persists for at least four cycles in continuous light (2 μE·m −2 ·s −1 ) and constant temperature (22, 20 or 16°C) with a maximum in dividing cells at about 24 h intervals. Thus, the prokaryote, Synechococcus, satisfies the criteria for the possession of a true temperature‐compensated circadian clock. Were the existence of such a rhythm confirmed, current hypotheses that intracellular compartments are required for circadian timing may require modification.
Sweeney et al. (Wed,) studied this question.