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Author (up) Takemura, A.; Ueda, S.; Hiyakawa, N.; Nikaido, Y. url  doi
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  Title A direct influence of moonlight intensity on changes in melatonin production by cultured pineal glands of the golden rabbitfish, Siganus guttatus Type Journal Article
  Year 2006 Publication Journal of Pineal Research Abbreviated Journal J Pineal Res  
  Volume 40 Issue 3 Pages 236-241  
  Keywords Animals; Circadian Rhythm; *Light; Melatonin/biosynthesis/*secretion; *Moon; Organ Culture Techniques; Perciformes/*physiology; Pineal Gland/physiology/*radiation effects  
  Abstract Rabbitfish are a restricted lunar-synchronized spawner that spawns around a species-specific lunar phase. It is not known how the fish perceive changes in cues from the moon. One possible explanation is that rabbitfish utilize changes in moonlight intensity to establish synchrony. The purpose of the present study was to examine whether or not the pineal gland of the golden rabbitfish can directly perceive changes in moonlight intensity. Isolated pineal glands were statically cultured under natural or artificial light conditions and melatonin secreted into the culture medium was measured using a time-resolved fluoroimmunoassay. Under an artificial light/dark cycle, melatonin secretion significantly increased during the dark phase. Under continuous light conditions, melatonin secretion was suppressed, while culture under continuous dark conditions seemed to duplicate melatonin secretion corresponding to the light/dark cycle in which the fish were acclimated. When cultured pineal glands were kept under natural light conditions on the dates of the full and the new moon, small amounts of melatonin were secreted at night. Moreover, exposure of cultured pineal glands to artificial and natural light conditions resulted in a significant decrease of melatonin secretion within 2 hr. These results suggest that the isolated pineal gland of golden rabbitfish responds to environmental light cycles and that 'brightness' of the night moon has an influence on melatonin secretion from the isolated pineal gland.  
  Address Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Motobu, Okinawa, Japan. tilapia@lab.u-ryukyu.ac.jp  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0742-3098 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16499560 Approved no  
  Call Number IDA @ john @ Serial 70  
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