Nitric oxide-donor SNAP induces Xenopus eggs activation

Area of Science:

• Cellular biology
• Developmental biology
• Reproductive biology

Background:

• Nitric oxide (NO) is a crucial signaling molecule in mammalian oocyte maturation and activation.
• Understanding NO's role in non-mammalian oocyte activation is essential for comparative developmental studies.

Purpose of the Study:

• To investigate the role of nitric oxide (NO) in the parthenogenetic activation of Xenopus oocytes.
• To elucidate the biochemical mechanisms underlying NO-induced oocyte activation.

Main Methods:

• Treatment of Xenopus eggs with a nitric oxide donor (SNAP) and an NO-scavenger (CPTIO).
• Observation of morphological changes (pigment rearrangement, pronucleus formation, cortical granule exocytosis).
• Biochemical analysis of maturation-promoting factor (MPF), MAPK, and Rsk activity.
• Measurement of intracellular calcium levels and assessment in calcium-depleted media.

Main Results:

• SNAP treatment induced parthenogenetic activation, evidenced by pigment rearrangement, pronucleus formation, and cortical granule exocytosis.
• SNAP exposure led to rapid inactivation of MAPK and Rsk, while MPF remained active, distinct from calcium ionophore effects.
• SNAP induced a significant increase in intracellular calcium, and its effects were diminished in calcium-free conditions.

Conclusions:

• Nitric oxide (NO) can induce parthenogenetic activation in Xenopus oocytes.
• NO-mediated activation involves the regulation of MAPK and Rsk pathways.
• The parthenogenetic activation of Xenopus oocytes by NO donors is largely dependent on intracellular calcium.