Figure 2.
Repression of frq9 mRNA accumulation by induction of FRQ protein is complete within a quarter of the circadian cycle. (A) Northern blot analysis of mRNA derived from frq9qa-2pfrq cultures incubated in 0, 1.5 × 10−4, 1.5 × 10−5, or 1.5 × 10−6 M QA for the times shown. mRNA was probed with a pCRM129ΔBB riboprobe, which recognizes the 5′UTR of the endogenous frq9 mRNA transcript but not that of the qa-2pfrq transcript. (B) The autoradiographic exposures from four repression experiments of the type shown in A were scanned for densitometric quantitation of mRNA levels. The data were pooled and graphed as the mean ± 2 SEM.