Figure 4. Reduced frq expression and loss of rhythmicity in SWI/SNF subunit knockouts as assayed by a luciferase reporter.

frq transcription in WT, Δswi1, Δsnf5, and Δswp59 was examined using the frq C box fused to codon-optimized firefly luciferase (transcriptional fusion). Strains were grown on 0.1% glucose racetube medium containing 5 mM luciferin in a 96 well plate and synchronized by growth in constant light for 48 hours followed by transfer to darkness. The luciferase signal was followed for longer than 6 days with sampling every 30 minutes. Each strain was repeated three times. Δswp59 showed a WT oscillation, Δsnf5 also oscillated in a circadian manner despite an extremely low amplitube, while frq trancription was completely abolished in Δswi1.