HughesLab:Research

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Discovery of circadian harmonics

Fig. 1: Hughes et al. (2009)
Transcriptional profiling of the mouse liver identified rhythmic transcripts with period lengths of ~8, ~12, and ~24 hours.

We profiled global gene expression over two full days using Affymetrix microarrays. We identified rhythmic transcripts in the mouse liver and pituitary, as well as fibroblasts (NIH3T3 cells) and osteosarcoma cells (U2OS). To our surprise, we found several hundred genes cycling with period lengths much shorter than 24 hours. These ultradian rhythms had period lengths of ~8 and ~12 hours -- i.e., the second and third harmonics of the core circadian oscillation.

System-driven circadian oscillations

Fig. 2: Hughes et al. (2012b)
~100 genes oscillate in the mouse liver, despite ablation of the local, peripheral clock.

Rhythms of snoRNA host genes

Fig. 3: Hughes et al. (2012a)
Non-coding, snoRNA host genes oscillate in the fly brain

<p style="font-size: 150%;"> Hughes Lab
Department of Biology
University of Missouri, St. Louis