Increase in intracellular cAMP is a prerequisite signal for initiation of physiological oocyte meiotic maturation in the hydrozoan Cytaeis uchidae

Noriyo Takeda, Keiichiro Kyozuka, Ryusaku Deguchi

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

In medusae of the hydrozoan Cytaeis uchidae, oocyte meiotic maturation and spawning occur as a consequence of dark-light transition. In this study, we investigated the mechanism underlying the initiation of meiotic maturation using in vitro (isolated oocytes from ovaries) and in vivo (ovarian oocytes in medusae) systems. Injection of cAMP derivatives into isolated oocytes induced meiotic maturation in a dose-dependent manner. Meiotic maturation was also achieved in isolated oocytes preloaded with caged cAMP and exposed to UV irradiation. The caged cAMP/UV irradiation-induced meiotic maturation was completely inhibited by blockers of protein kinase A (PKA), H-89, KT5720, and Rp-cAMPS. The medusae from which most parts of the umbrella were removed (umbrella-free medusae) survived for at least 2 weeks, during which time oocyte meiotic maturation and spawning occurred. When H-89 and Rp-cAMPS were injected into ovarian oocytes of umbrella-free medusae within 3 min of dark-light stimulation, meiotic maturation was inhibited or delayed. An increase in intracellular cAMP was confirmed by FlCRhR, a fluorescent cAMP indicator, in ovarian oocytes exposed to dark-light transition as well as in isolated oocytes stimulated by caged cAMP/UV irradiation. These results indicate that the cAMP/PKA signaling pathway positively contributes to light-triggered physiological oocyte meiotic maturation in Cytaeis uchidae.

Original languageEnglish
Pages (from-to)248-258
Number of pages11
JournalDevelopmental Biology
Volume298
Issue number1
DOIs
Publication statusPublished - 2006 Oct 1

Keywords

  • 8-Br-cAMP
  • Caged cAMP
  • Cyclic AMP
  • GVBD
  • H-89
  • Jellyfish
  • Meiosis
  • Spawning
  • Umbrella-free medusa
  • cAMP-dependent protein kinase

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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