ZFIN ID: ZDB-PUB-061031-17
Spectral sensitivity of melatonin suppression in the zebrafish pineal gland
Ziv, L., Tovin, A., Strasser, D., and Gothilf, Y.
Date: 2007
Source: Experimental Eye Research   84(1): 92-99 (Journal)
Registered Authors: Gothilf, Yoav, Ziv, Limor
Keywords: light, melatonin, pineal, zebrafish, action spectrum
MeSH Terms:
  • Animals
  • Circadian Rhythm/physiology
  • Female
  • Gene Expression Regulation/radiation effects
  • Light*
  • Male
  • Melatonin/biosynthesis*
  • Organ Culture Techniques/methods
  • Photic Stimulation/methods
  • Pineal Gland/metabolism
  • Pineal Gland/radiation effects*
  • Reverse Transcriptase Polymerase Chain Reaction/methods
  • Rod Opsins/genetics
  • Rod Opsins/metabolism
  • Zebrafish/metabolism*
PubMed: 17067577 Full text @ Exp. Eye. Res.
The pineal gland of the zebrafish (Danio rerio) is a clock-containing photoreceptive organ. Superfused pineal glands kept in darkness display rhythmic melatonin production that lasts for days, with high melatonin levels during the night and low levels during the day. Nocturnal light, however, evokes an acute suppression of melatonin synthesis in the photoreceptor cells. Towards characterizing zebrafish pineal photopigment that is involved in the acute melatonin suppression we have measured the spectral sensitivity of melatonin-suppression response in superfused pineal glands. The effect of 2h light exposure of seven wavelengths (lambda(avg) 408, 460, 512, 560, 608, 660 and 697+/-10-15nm) at multiple irradiances (10(7)-10(14) photons/cm(2)/s) was determined, and an action spectrum was plotted. The resultant action spectrum provides evidence for the involvement of multiple photopigments in melatonin suppression. The most efficient melatonin-suppression response was achieved by exposure to light of around 512nm; however, another peak of lower irradiance sensitivity was observed in the middle to long wavelengths. Opsins-specific RT-PCR analysis confirmed the expression of exo-rhodopsin and visual red-sensitive opsin in the pineal gland, while other zebrafish visual opsins as well as VA and VAL opsins were not detected. Dartnall monograms for exo-rhodopsin and visual red-sensitive opsin account for most but not all of the spectral sensitivity features. Therefore, additional pineal photopigments may contribute to the melatonin-suppression response in the pineal gland.