FIG. 2.

Daily cycling of dClock mRNA in heads from wild-type D. melanogaster. (A) Autoradiogram of dClock, per, tim, and RP49 transcripts in wild-type flies during a 12-h LD cycle. Levels of dClock, per, tim, and RP49 transcripts were determined by RNase protection assays (see Materials and Methods). (B) Quantitation of results shown in panel A. Time course of dClock, per, and tim transcript levels in wild-type flies during 12-h LD conditions. Peak levels for each mRNA were set to 100. Relative RNA level refers to ratio of dClock, per, or tim transcripts to RP49 RNA. Closed bar, darkness; open bar, light. Similar results were obtained in five independent experiments, and a representative example is shown.