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首页> 外文期刊>Zoological Science >Arrest at Metaphase of Meiosis I in Starfish Oocytes in the Ovary is Maintained by High CO2 and Low O-2 Concentrations in Extracellular Fluid
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Arrest at Metaphase of Meiosis I in Starfish Oocytes in the Ovary is Maintained by High CO2 and Low O-2 Concentrations in Extracellular Fluid

机译：卵巢中海星卵母细胞卵母细胞减数分裂I中期的逮捕由细胞外液中高CO2和低O-2浓度维持

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During the spawning process in starfish, oocytes are arrested at metaphase of meiosis I (MI) within the ovary, and reinitiate meiosis only after they have been released into the seawater. However, this arrest does not occur if the ovary is removed from the animal. As the pH of the coelomic fluid is buffered by CO2/H+/HCO3-, we investigated the involvement of gas concentrations in MI arrest. In vivo, the CO2 level in the coelomic fluid was high (similar to 1.5% vs. 0.04% in air) and the O-2 level was low (0.1-1.0% vs. similar to 20% in air). When these gas conditions were reproduced in isolated coelomic fluid or seawater, ovarian oocytes arrested at MI, just as in vivo. Isolated oocytes from the ovary required the similar high CO2 and low O-2 level to remain arrested in MI and had an intracellular pH of similar to 6.9. Intracellular pH increased to similar to 7.3 when oocytes were transferred to seawater equilibrated with air, a condition that mimics that of spawning. We used ammonium acetate to clamp intracellular pH at different levels and found that MI arrest occurred when intracellular pH was similar to 6.9. Our results support the idea that high CO2 and low O-2 in the ovarian environment lead to low intracellular pH and MI arrest, while spawning into the seawater with low CO2 and high O-2 results in high intracellular pH and release from MI arrest. The biological significance of MI arrest is that oocytes are spawned into seawater at the optimal physiological state of MI when the least polyspermy occurs.
机译：在海星的产卵过程中，卵母细胞停滞在卵巢内减数分裂I（MI）的中期，只有在它们释放入海水后才重新开始减数分裂。但是，如果从动物中取出卵巢，则不会发生这种停止。由于结肠流体的pH受CO2 / H + / HCO3-缓冲，我们研究了气体浓度与MI阻滞有关。在体内，腔体液中的CO2水平较高（大约为1.5％，而在空气中为0.04％），而O-2水平较低（0.1-1.0％，而在空气中为20％）。当这些气体条件在隔离的腔体液或海水中繁殖时，卵巢卵母细胞就象在体内一样停滞在心肌梗死中。从卵巢中分离出的卵母细胞需要相似的高CO2和低O-2水平才能保持在MI中，并且细胞内pH值应接近6.9。当卵母细胞转移到空气中平衡的海水中时，细胞内pH值增加到7.3，类似于产卵的情况。我们用乙酸铵将细胞内的pH值固定在不同的水平，发现当细胞内的pH值与6.9相似时，心肌梗死发生了。我们的结果支持以下观点：卵巢环境中的高CO2和低O-2导致低的细胞内pH和MI捕获，而产卵到具有低CO2和高O-2的海水中则导致高的细胞内pH并从MI捕获释放。 MI停滞的生物学意义是当最少精子发生时，卵母细胞以MI的最佳生理状态产卵到海水中。

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