On the chronobiology ofTetrahymena. II. Further evidence for the persistence of ultradian rhythmicity in the absence of protein synthesis and cell growth∗∗

Publisher Website
Google Scholar
Abstract
In Tetrahymena thermophila, the ultradian rhythm of tyrosine aminotransferase activity was investigated under free-running conditions. The rhythm persisted in the presence of 1 mM emetine, although the drug efficiently inhibited both protein synthesis and cell division. Also 250 mM hydroxyurea, which suppressed cell growth to a high degree, did not prevent the rhythm. These data support the concept of an ultradian oscillator working independently of translation and being not a consequence of the cell cycle, although under normal physiological conditions the rhythm of tyrosine aminotransferase is accompanied by and equiperiodic with the rhythm of cell division, both in the ultradian and circadian growth modes.