Zhou H M, Jin S Y
College of Bioengineering, Inner Mongolia Agricultural University, Hohhot, China.
Reprod Domest Anim. 2007 Oct;42(5):555-9. doi: 10.1111/j.1439-0531.2006.00824.x.
In this study, we investigated the fluctuations of concentration of intracytoplasmic free Ca(2+) during in vitro maturation of caprine primary oocytes and its role in meiotic resumption. Oocytes that were extracted from caprine ovaries were cultured and allowed to mature in vitro to determine their developmental stages including germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase of the first meiotic division (MI) and metaphase of the second meiotic division (MII). Intracytoplasmic free Ca(2+) turnovers of caprine oocytes at these different developmental stages were measured using the calcium fluorescent probe Fura-2/AM (C(44)H(47)N(3)O(24)) to investigate the dynamics of cytosolic free Ca(2+) during in vitro maturation of oocytes and the role of Ca(2+) in inducing the initiation of meiotic resumption of oocytes. Moreover, the oocytes were cultured in Ca(2+) culture medium and Ca(2+)-free culture medium to examine the effect of extracellular Ca(2+) on the oocyte maturation. The results indicated that Ca(2+) concentrations at GV, GVBD, MI and MII stages were 78.06, 147.41, 126.97 and 97.73 nmol/l, respectively, and that 86.30% of oocytes remained at the GV stage and no oocyte developed to MII in Ca(2+)-free culture medium, and 1.1% of oocytes stayed at the GV stage and 83.5% of oocytes developed to MII in Ca(2+) culture medium. These results suggest that the occurrence of GVBD and cell cycle progression to MI and MII stages are closely related to Ca(2+), and that extracellular Ca(2+) performs a specific function for the initiation of meiotic resumption in caprine oocytes.
在本研究中，我们调查了山羊初级卵母细胞体外成熟过程中胞质游离钙离子浓度的波动情况及其在减数分裂恢复中的作用。从山羊卵巢中提取的卵母细胞进行培养并使其体外成熟，以确定其发育阶段，包括生发泡（GV）、生发泡破裂（GVBD）、第一次减数分裂中期（MI）和第二次减数分裂中期（MII）。使用钙荧光探针Fura-2/AM（C₄₄H₄₇N₃O₂₄）测量山羊卵母细胞在这些不同发育阶段的胞质游离钙周转情况，以研究卵母细胞体外成熟过程中胞质游离钙的动态变化以及钙离子在诱导卵母细胞减数分裂恢复起始中的作用。此外，将卵母细胞分别培养于含钙培养基和无钙培养基中，以检测细胞外钙离子对卵母细胞成熟的影响。结果表明，GV、GVBD、MI和MII阶段的钙离子浓度分别为78.06、147.41、126.97和97.73 nmol/L，并且在无钙培养基中86.30%的卵母细胞停滞在GV阶段，没有卵母细胞发育至MII阶段，而在含钙培养基中1.1%的卵母细胞停滞在GV阶段，83.5%的卵母细胞发育至MII阶段。这些结果表明，GVBD的发生以及细胞周期向MI和MII阶段的进展与钙离子密切相关，并且细胞外钙离子在山羊卵母细胞减数分裂恢复起始中发挥特定作用。
