Figure 5.

Interaction of selenium with the environmental and circadian cycles: (a,b) Cellular content of selenium, analysed by inductively coupled plasma mass spectrometry. The two detectable stable isotopes of selenium are ⁷⁸Se (left) and ⁸²Se (right), and these were measured under LD (a) or LL (b) conditions. Mean ± SEM; n = 3. (c,d) Luminescent imaging of the CCA1-LUC circadian clock marker under normal physiological concentrations of extracellular selenium (control) versus depleted levels 2 or 4 orders of magnitude lower. Cells were imaged over multiple cycles of 12 h/12 h light/dark (LD, (c)) or constant light (LL, (d)). Mean ± SEM; n = 32.