Luciferin assimilated by drinking enables long-term bioluminescence imaging.

Shown is a female non-anesthetized, freely moving Hr-Per1 mouse imaged after oral luciferin delivery (1 mM luciferin in apple juice). Frames were captured with 0.5 second exposures within a 15-min imaging sequence and selected by eye according to body shape contours. Top row: in the extended posture. Bottom: curled posture. The intensity range is in ADUs with 20x EM gain.