GFP fluorescence reports PeriodI circadian gene regulation in the mammalian biological clock

Endogenous cyclic activation of a specific set of genes, including Period1 (Per1), drive circadian rhythms in the suprachiasmatic nucleus (SCN), a bio logical clock nucleus of the brain. We have produced transgenic mice in whi ch a degradable form of recombinant jellyfish green fluorescent protein (GF P) is driven by the mouse Period1 (mPer1) gene promoter. GFP protein is exp ressed in the circadian neural structures of the retina and SCN. Fluorescen t signals are resolved at the level of individual neurons, mPer1-driven GFP fluorescence intensity reports light-induction and circadian rhythmicity i n SCN neurons. This circadian reporter transgene captures the gene expressi on dynamics of living biological clock neurons and ensembles, providing a n ovel view of this brain function. NeuroReport 11:1479-1482 (C) 2000 Lippinc ott Williams & Wilkins.