Genes to cells : devoted to molecular & cellular mechanismsSep 27, 2006

New system tracking Per1 and Bmal1 shows ongoing daily rhythms in body tissues

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Mar 30, 2026

Abstract

Circadian rhythms in Bmal1-FL in peripheral tissues persisted for more than 3 weeks.

A new reporter system was established to monitor the expression of Per1 and Bmal1 genes in cultured mouse tissue.
Circadian rhythms for Per1 and Bmal1 in the suprachiasmatic nucleus were robust and anti-phasic.
These rhythms were phase delayed by 4-8 hours compared to the corresponding transcript levels observed in vivo.
Circadian rhythms in peripheral tissues maintained a long-term oscillation despite external changes.
Refreshment of culture medium restored dampened circadian rhythms, but this restoration did not indicate a resetting of oscillation.

Simplified

A new reporter system for monitoring expressions of two clock genes, Per1 and Bmal1, from a single tissue in culture was developed in mice. Reporters are Vargula hilgendorfii luciferase (VL) and firefly luciferase (FL), whose activities are increased in parallel with Per1 and Bmal1 expressions, respectively. Formal properties of the circadian system in transgenic mice are indistinguishable from those in wild-type animals. Circadian rhythms in Per1-VL and Bmal1-FL in the suprachiasmatic nucleus (SCN) were robust and anti-phasic, although they were phase delayed by 4-8 h as compared with circadian rhythms in respective transcript levels in vivo. In peripheral tissues such as liver, circadian rhythms in Bmal1-FL persisted for more than 3 weeks. In the course of prolonged culture, circadian rhythms apparently damped out, but were restored immediately by refreshment of the culture medium. Restoration of the circadian rhythm is unlikely to be due to resetting of desynchronized population oscillation, because peripheral circadian rhythms did not show a type 0 phase response curve (PRC) for medium refreshment, a requirement for instantaneous resetting of circadian oscillation. Long-term persistence of circadian oscillation in spite of external perturbations supports an idea that circadian oscillations in peripheral tissues are self-sustained.

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New system tracking Per1 and Bmal1 shows ongoing daily rhythms in body tissues

Abstract

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