Involvement of Ca2+Signaling Pathway During Oocyte Maturation of the Northern QuahogMercenaria mercenaria

In many molluscs, it has been found that Ca2 signaling pathway is involved in the resumption of meiotic maturation in oocytes. To better understand the possible role of Ca2 signaling pathway in regulating meiotic maturation in oocytes of the northern quahog Mercenaria mercenaria, free extracellular Ca2 , A23187 (calcium ionophore), verapamil (calcium channel blocker), and trifluoperazin (calmodulin antagonist) were used to incubate oocytes or serotonin-induced oocytes by pharmacological methods. Results show that extracellular Ca2 (50 ∼ 10 µM) and A23187 (1 ∼ 10 µM) can stimulate the meiotic maturation. In addition, verapamil (1 ∼ 100 µM) and trifluoperazin (10 ∼ 1,000 µM) could inhibit serotonin-induced oocyte maturation. Therefore, Ca2 is essential for the reinitiation of meiotic maturation in oocytes of the northern quahog. Moreover, an increase in [Ca2 ]i can promote meiotic maturation.