Nitric oxide (NO) increase at fertilization in sea urchin eggs upregulates fertilization envelope hardening

Tatsuma Mohri, Masahiro Sokabe, Keiichiro Kyozuka

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Previous studies indicate that the nitric oxide (NO) increase at fertilization in sea urchin eggs is Ca2+-dependent and attributed to the late Ca2+ rise. However, its role in fertilization still remains unclear. Simultaneous measurements of the activation current, by a single electrode voltage clamp, and NO, using the NO indicator DAF-FM, showed that the NO increase occurred at the time of peak current (tp) which corresponds to peak [Ca2+]i, suggesting that NO is not related to any other ionic changes besides [Ca2+]i. We measured O2 consumption by a polarographic method to examine whether NO regulated a respiratory burst for protection as reported in other biological systems. Our results suggested NO increased O2 consumption. The fluorescence of reduced pyridine nucleotides, NAD(P)H was measured in controls and when the NO increase was eliminated by PTIO, a NO scavenger. Surprisingly, PTIO decreased the rate of the fluorescence change and the late phase of increase in NAD(P)H was eliminated. PTIO also suppressed the production of H2O2 and caused weak and high fertilization envelope (FE). Our results suggest that NO increase upregulates NAD(P)H and H2O2 production and consolidates FE hardening by H2O2.

Original languageEnglish
Pages (from-to)251-262
Number of pages12
JournalDevelopmental Biology
Issue number2
Publication statusPublished - 2008 Oct 15


  • 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO)
  • Ca
  • Cyclic adenosine diphosphate ribose (cADPR)
  • Diaminofluorescein-FM (DAF-FM)
  • Diphenyleneiodonium (DPI)
  • Fertilization envelope (FE)
  • Inositol 1,4,5-trisphosphate (InsP)
  • Nitric oxide (NO)
  • O consumption
  • Reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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