Figure 5.

Differences in mRNA levels in the brains of young laboratory-reared bees and foragers. Northern blot (A) and densitometric analyses (B) (normalization as in Fig. 3). Result of statistical analyses (paired t test) indicated on graph (n = 4 time points per group, 4–10 brains per time point). Two transcripts were detected, and both appear to cycle in circadian fashion. We do not know whether they are alternative transcripts of alleles, splice variants, or whether the larger transcript is a pre-mRNA; Southern analyses indicate one copy of per in the bee genome (D.P.T., Y. Ben-Shahar, A. Tam, and G.E.R., unpublished observations). Values for both transcripts were summed (analyses with major transcript alone gave the same results). The large size of both transcripts relative to the entire coding region is consistent with previous reports (26).