Effect of photoperiod on clock gene expression and subcellular distribution of PERIOD in the circadian clock neurons of the blow fly Protophormia terraenovae

Abstract

We examined the effect of photoperiod on the expression of circadian clock genes period (per) and timeless (tim), using quantitative real-time polymerase chain reaction (PCR), and the effect of photoperiod on subcellular distribution of PERIOD (PER), using immunocytochemistry, in the blow fly, Protophormia terraenovae. Under both short-day and long-day conditions, the mRNA levels of per and tim in the brain oscillated, and their peaks and troughs occurred around lights-off and lights-on, respectively. The oscillations persisted even under constant darkness. In the large ventral lateral neurons (l-LN(v)s), small ventral lateral neurons (s-LN(v)s), dorsal lateral neurons (LN(d)s), and medial dorsal neurons (DN(m)s), the subcellular distribution of PER-immunoreactivity changed with time. The number of cells with PER-immunoreactivity in the nucleus was highest 12 h after lights-off and lowest 12 h after lights-on, regardless of photoperiod, suggesting that PER nuclear translocation entrains to photoperiod. When temporal changes in the nuclear localization of PER were compared, the neurons could be classified into 2 groups: the l-LN(v)s were similar to the s-LN(v)s, and the LN(d)s were similar to DN(m)s. In LN(d)s and DN(m)s, decreasing rates of the number of cells with PER immunoreactivity in the nucleus per brain from the maximum were large as compared with those in l-LN(v)s and s-LN(v)s under short-day conditions. These results suggest that photoperiodic information is reflected in the expression patterns of circadian clock genes per and tim and in the subcellular distribution of PER. This observation suggests that the 2 different groups of clock neurons respond to photoperiod in slightly different manners.

Phylogeny and oscillating expression ofperiodandcryptochromein short and long photoperiods suggest a conserved function inNasonia vitripennis

“…Per mRNA oscillation typically displays a peak generally at light-off or the first part of the dark phase and a trough in the light phase, irrespective of the photoperiod. This has been observed in the hymenopterans A. mellifera (Rubin et al, 2006), A. cerana (Shimizu et al, 2001), and Solenopsis invicta (Ingram et al, 2012); in the dipterans Drosophila melanogaster (Qiu & Hardin, 1996), A. aegypti, Culex quinquefasciatus (Gentile et al, 2009), Protophormia terranovae (Muguruma et al, 2010), Sarcophaga crassipalpis (Goto & Denlinger, 2002; Kostál et al, 2009), Chymomyza costata (Kobelková et al, 2010), and Sarcophaga bullata (Goto et al, 2006); in the cricket Modicogryllus siamensis (Sakamoto et al, 2009), the cockroach Rhyparobia maderae (Werckenthin et al, 2012), and in the lepidopterans Bombyx mori (Iwai et al, 2006), Danaus plexippus (Zhu et al, 2008), and Spodoptera littoralis (Merlin et al, 2007). In species where cry2 (or “vertebrate-like” cry) is present, its oscillation matches that of per , as found in our study, with a trough in the light phase and a peak in the dark phase (Gentile et al, 2009; Ikeno et al, 2008; Ingram et al, 2012; Merlin et al, 2007; Rubin et al, 2006; Werckenthin et al, 2012; Yan et al, 2013; Zhu et al, 2008).…”

Myoinhibitory peptide (MIP) immunoreactivity in the visual system of the blowfly Calliphora vomitoria in relation to putative clock neurons and serotonergic neurons

“…Neurons similar to the ITPexpressing 5th s-LN v and a single LN d (Johard et al 2009) have been detected in each hemisphere of the brain of Calliphora together with the other ipc-1 and ipc-2 neurons. As defined by the expression of the clock protein PERIOD, clock neurons of the s-LN v and LN d type have been identified in blowflies (Muguruma et al 2010;Shiga and Numata 2009). Thus, the ITP-IR neurons resembling s-LN v and LN d are probably indeed clock neurons.…”

“…6d-f, k). Notably, clock gene expression was revealed in neurons resembling LN d s and LN v s in the blowfly Protophormia terraenovae (Muguruma et al 2010;Shiga and Numata 2009), suggesting that the two ITP-IR neurons discussed above might indeed be clock neurons. Representations summarizing the neurons revealed above in Calliphora and Drosophila are shown in Fig.…”

Photoperiodic plasticity in circadian clock neurons in insects

“…In fact, the mRNA of per and tim of the head sample reach their peaks in abundance 4 h after “light-off” during photoperiods of 16-h light and 8-h darkness (LD, 16:8), LD 12:12, and LD 8:16, and oscillation uses “lights-off” as a phase reference point (Qiu and Hardin, 1996). Setting peaks of per or tim mRNA levels at “lights-off” have also been observed in the head of the flesh fly Sarcophaga crassipalpis , the whole central nervous system of C. costata , and the brain of P. terraenovae (Goto and Denlinger, 2002; Stehlík et al, 2008; Muguruma et al, 2010). Other types of responses of circadian clock gene expression to photoperiods have also been observed.…”