PDFR-MYC expression by identified pacemaker neurons. (A–D) Six of the 17 DN1s express PDFR-MYC at strong levels, whereas three or four of the remaining ones express it at lower levels. (A) Merged image of (B) (PDF, magenta), (C) (PER, blue), and (D) (MYC, green). (E–H) LNvs express PDFR-MYC. (E) Merged image of (F) (PDF, magenta), (G) (PER, blue), and (H) (MYC, green). The 5th s-LNv expresses high levels of PDFR-MYC (arrow), two l-LNvs express PDFR-MYC at intermediate levels (arrowhead), while the others have lower to undetectable levels. s-LNvs are best seen in panel (I). Red asterisks indicate the incidence of non-pacemaker, receptor-positive cell bodies. (I–K) s-LNvs express PDFR-MYC. (I) Merged image of (J) (MYC, green) and (K) (PDF, magenta). Red asterisks indicate the incidence of non-pacemaker, receptor-positive cell bodies. (L–N) Three LNds out of six show very strong PDFR-MYC expression (white arrowheads), whereas the others show no PDFR-MYC (magenta arrowheads). (L) Merged image of (M) (MYC, green) and (N) (PER, blue). Asterisk, non-specific MYC signal near LNd area. (O–Q) Single optical section reveals low-level PDFR-MYC expression by DN2s (arrow). (O) Merged image of (P) (MYC, green) and (Q) (PER, blue). (R–T) DN3s express PDFR-MYC at low levels. (R) Merged image of (S) (MYC, green) and (T) (PER, blue). Scale bars, 10 μm.