Circadian clocks in monarch antennae. (A) Clock gene expression in monarch tissues. Tissues were collected at ZT 6 (white bars) and ZT18 (black bars). Values are normalized to those in the brain at ZT18 and are mean ± SEM of 4 animals. p-values, Student’s t-test: ***p < 0.001; **p < 0.01; *, p < 0.05. (B) Clock gene mRNA profiles in antennae. Values are relative to the minimal level for each gene and are the mean ± SEM of 4 antennae. Points at CT0 are replotted at CT24. Horizontal bars: gray, subjective day; black, subjective night. p-values, one-way ANOVA. (C) Circadian profiles of clock protein abundance in antennae. Top, representative autoradiographs in DD. Arrowhead, CRY2 band; the lower band is non-specific, as shown previously (). Bottom four graphs, quantification of relative protein levels. Values are normalized to the minimal level of protein expression and are mean ± SEM of 3–4 antennae. p-values, one-way ANOVA. (D) Light-sensitivity of antennae in culture. Top, experimental scheme in LD or in phase-reversed LD (R-LD). Arrows, collection times. Bottom, western blot analyses. Left, representative blots; right, quantifications. Open bars, mid-light; black bars, mid-dark. Values are mean ± SEM of 5 antennae. p-values, Student’s t-test: **, p < 0.01; *, p < 0.05. (E) Daily and circadian patterns of TIM abundance in two sets of cultured antennae (gray and black lines). Top, lighting conditions. Bottom, representative western blot.