Existence of an extra-retinal and extra-pineal photoreceptive organ that regulates photoperiodism in gonadal development of an Osmerid teleost, ayu (Plecoglossus altivelis)

Tomohiro Masuda, Masayuki Iigo, Katsumi Aida

Research output: Contribution to journalArticle

Abstract

Ayu (Plecoglossus altivelis) is an Osmerid teleost whose gonadal development exhibits clear photoperiodism: it is stimulated and prevented under short and long photoperiod, respectively. However, the photoreceptor organ involved in this process remains to be identified. In the present study, we examined whether gonads of ophthalmectomized (Ex) and pinealectomized (Px) ayu respond to short photoperiod to test whether photoreceptors other than lateral eyes and pineal complex are involved in the photoperiodic response of gonadal development. Gonadosomatic index (GSI) and plasma levels of sex steroids (testosterone and 11-ketotestosterone for males and testosterone and estradiol 17-β for females) were significantly increased in the Ex+Px ayu kept under short photoperiod in both males and females as compared with the initial control. On the other hand, there were no significant increases in GSI and sex steroids in the Ex+Px ayu kept under long photoperiod. Histological observation of gonads in the Ex+Px ayu revealed that oocytes undergoing final maturation in females and proliferation of germ cells in males were observed under short photoperiod but not under long photoperiod. These results indicate that extra-retinal and extra-pineal photoreceptive organ regulates photoperiodic gonadal development in this species.

Original languageEnglish (US)
Pages (from-to)414-422
Number of pages9
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Volume140
Issue number4
DOIs
StatePublished - Apr 2005

Keywords

  • Ayu Plecoglossus altivelis
  • Extra-pineal and extra-retinal photoreceptor
  • Gonadal development
  • Gonadosomatic index
  • Lateral eyes
  • Photoperiodism
  • Pineal complex
  • Sex steroids

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology

Fingerprint Dive into the research topics of 'Existence of an extra-retinal and extra-pineal photoreceptive organ that regulates photoperiodism in gonadal development of an Osmerid teleost, ayu (Plecoglossus altivelis)'. Together they form a unique fingerprint.

  • Cite this