Early development of circadian rhythmicity in the suprachiamatic nuclei and pineal gland of teleost, flounder (Paralichthys olivaeus), embryos

Makoto Mogi, Susumu Uji, Hayato Yokoi, Tohru Suzuki

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Circadian rhythms enable organisms to coordinate multiple physiological processes and behaviors with the earth's rotation. In mammals, the suprachiasmatic nuclei (SCN), the sole master circadian pacemaker, has entrainment mechanisms that set the circadian rhythm to a 24-h cycle with photic signals from retina. In contrast, the zebrafish SCN is not a circadian pacemaker, instead the pineal gland (PG) houses the major circadian oscillator. The SCN of flounder larvae, unlike that of zebrafish, however, expresses per2 with a rhythmicity of daytime/ON and nighttime/OFF. Here, we examined whether the rhythm of per2 expression in the flounder SCN represents the molecular clock. We also examined early development of the circadian rhythmicity in the SCN and PG. Our three major findings were as follows. First, rhythmic per2 expression in the SCN was maintained under 24 h dark (DD) conditions, indicating that a molecular clock exists in the flounder SCN. Second, onset of circadian rhythmicity in the SCN preceded that in the PG. Third, both 24 h light (LL) and DD conditions deeply affected the development of circadian rhythmicity in the SCN and PG. This is the first report dealing with the early development of circadian rhythmicity in the SCN in fish.

Original languageEnglish
Pages (from-to)444-452
Number of pages9
JournalDevelopment Growth and Differentiation
Volume57
Issue number6
DOIs
Publication statusPublished - 2015 Aug 1

Keywords

  • Circadian rhythm
  • Early development
  • Flounder
  • Pineal gland
  • Suprachiasmatic nucleus

ASJC Scopus subject areas

  • Developmental Biology
  • Cell Biology

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