Time course of gene expression of 24-, 12-, and 8-hour periods. Bright yellow depicts gene expression twice that of the median level while bright blue depicts expression less than 50 percent of the median level. The time of peak expression of 24-hour cycling genes show a roughly equal distribution over the course of a day. In contrast, peak expression of both 12-hour peaks correlate with subjective dusk and dawn.
Credit: Michael Hughes, PhD, University of Pennsylvania School of Medicine
Download high-resolution version (TIFF)