Discovery of circadian harmonics
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
Rhythms of snoRNA host genes
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Department of Biology
University of Missouri, St. Louis