Two circadian oscillators in one cell.

Roenneberg, Till; Morse, David · Nature · 1993

basic_science · Level V

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Abstract

A CIRCADIAN clock, which continues to oscillate in constant conditions, is almost ubiquitous in eukaryotes as well as some prokaryotes<sup>1</sup>. This class of biological oscillators drives daily rhythms as diverse as photosynthesis in plants<sup>2</sup> and the sleep-wake cycle in man<sup>3</sup> and enables organisms to anticipate environmental changes or segregate in time-incompatible processes<sup>4</sup>. Circadian oscillators share many properties, suggesting that the clock is a single mechanism, preserved throughout evolution, which is capable of controlling all the different circadian functions. Here we show that two rhythms in a unicellular organism can, under certain experimental conditions, run independently, and thus each rhythm must be controlled by its own distinct oscillator.