Moonlight affects mRNA abundance of arylalkylamine N‐acetyltransferase in the retina of a lunar‐synchronized spawner, the goldlined spinefoot

Abstract

Melatonin synthesis in the pineal gland and retina shows a rhythmic fashion with high levels at night and is controlled by a rate-limiting enzyme, arylalkylamine N-acetyltransferase (AANAT). A previous study revealed that moonlight suppresses the plasma melatonin levels of the goldlined spinefoot (Siganus guttatus), which exhibits a lunar cycle in its reproductive activity and repeats gonadal development toward and spawning around the first quarter moon. Whether the retina of this species responds to moonlight is unknown. To clarify the photoperceptive ability of this species, we aimed to clone the full-length cDNA of Aanat1 (sgAanat1) from the retina and examine its transcriptional pattern under several daylight and moonlight regimes. The full-length sgAanat1 cDNA (1,038 bp) contained a reading frame encoding a protein of 225 amino acids, which was highly homologous to AANAT1 of other teleosts. Reverse transcription-polymerase chain reaction (PCR) analysis revealed that among the tissues tested, sgAanat1 fragments were expressed exclusively in the retina. Real-time quantitative PCR analysis revealed that sgAanat1 fluctuated with high abundance at night under light-dark cycle and at subjective night under constant darkness, but not under constant light. These results suggest that sgAanat1 is regulated by both the external light signal and internal clock system. The abundance of sgAanat1 in the retina was higher at the culmination time around new moon than full moon phase. Additionally, exposing fish to brightness around the full moon period suppressed sgAanat1 mRNA abundance. Thus, moonlight is perceived by fish and has an impact on melatonin fluctuation in the retina.

Homeostatic Plasticity Mediated by Rod-Cone Gap Junction Coupling in Retinal Degenerative Dystrophic RCS Rats

“…Melatonin synthesis occurs in a rhythmic pattern that modulates rod-cone gap junction coupling (Day et al, 2010; Sandu et al, 2011; Hiragaki et al, 2014), and this process is controlled by the rate-limiting enzyme arylalkylamine N-acetyltransferase (AANAT; Sakamoto and Ishida, 1998; Pozdeyev et al, 2006; Kashiwagi et al, 2013). AANAT is activated by PKC-mediated phosphorylation at Thr29 (Choi et al, 2004).…”

Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

“…Four of the selected studies assessed changes in ocular melatonin levels at nocturnal illumination by white light (Table 3C), and only one study investigated the effects of different light colors [62] ( Table 3D). The expression of sgAanat1 was reduced under full-moon illumination compared to new moon in the gold-lined spinefoot [68]. Likewise, in another siganid, the seagrass rabbitfish, and in the wrasse (Halichaoeres tenuispinnis, Labridae), ocular melatonin was reduced at different intensities of white light [58,69].…”

Transcriptome dynamics over a lunar month in a broadcast spawning acroporid coral

“…In marine fishes, decreased transcription of AANT , a rate‐limiting enzyme in melatonin production (Kashiwagi et al . ), has been reported on full moon evenings, as have altered Period and Cryptochrome transcription (Fukushiro et al . ).…”

“…In the fruit fly Drosophila, both nocturnal behaviour and Clock protein levels can shift in response to quarter moon levels of illumination at night (Bachleitner et al 2007). In marine fishes, decreased transcription of AANT, a rate-limiting enzyme in melatonin production (Kashiwagi et al 2013), has been reported on full moon evenings, as have altered Period and Cryptochrome transcription (Fukushiro et al 2011). A marine polychaete also shows differences in gene expression under laboratory conditions between new moon and constant full moon for Clock, Period and Pdp1 genes (Zantke et al 2013).…”