Mitochondria are highly dynamic organelles and their distribution, structure and activity affect a wide range of cellular functions. Mitochondrial membrane potential (∆Ψm) is an indicator of mitochondrial activity and plays a major role in ATP production, redox balance, signaling and metabolism. Despite the absolute reliance of oocyte and early embryo development on mitochondrial function, there is little known about the spatial and temporal aspects of ΔΨm during oocyte maturation. The one exception is that previous findings using a ΔΨm indicator, JC-1, report that mitochondria in the cortex show a preferentially increased ΔΨm, relative to the rest of the cytoplasm. Using live-cell imaging and a new ratiometric approach for measuring ΔΨm in mouse oocytes, we find that ΔΨm increases through the time course of oocyte maturation and that mitochondria in the vicinity of the first meiotic spindle show an increase in ΔΨm, compared to other regions of the cytoplasm. We find no evidence for an elevated ΔΨm in the oocyte cortex. These findings suggest that mitochondrial activity is adaptive and responsive to the events of oocyte maturation at both a global and local level. In conclusion, we have provided a new approach to reliably measure ΔΨm that has shed new light onto the spatio-temporal regulation of mitochondrial function in oocytes and early embryos.

中文翻译：

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卵母细胞成熟过程中线粒体膜电位的时空动态。

线粒体是高度动态的细胞器，它们的分布，结构和活性影响广泛的细胞功能。线粒体膜电位（ΔΨm）是线粒体活性的指标，在​​ATP产生，氧化还原平衡，信号传导和代谢中起着重要作用。尽管卵母细胞和早期胚胎发育绝对依赖线粒体功能，但在卵母细胞成熟过程中ΔΨm的时空方面知之甚少。一个例外是先前使用ΔΨm指示剂JC-1的发现报告说，相对于其他细胞质，皮质中的线粒体显示出ΔΨm优先增加。使用活细胞成像和一种新的比例方法来测量小鼠卵母细胞中的ΔΨm，我们发现，随着卵母细胞的成熟，ΔΨm逐渐增加，与减数分裂的胞浆区相比，第一个减数分裂纺锤体附近的线粒体的ΔΨm有所增加。我们没有发现卵母细胞皮层中ΔΨm升高的证据。这些发现表明，线粒体活性在全局和局部水平上均对卵母细胞成熟事件具有适应性和响应性。总之，我们提供了一种可靠地测量ΔΨm的新方法，这为卵母细胞和早期胚胎中线粒体功能的时空调控提供了新的思路。这些发现表明，线粒体活性在全局和局部水平上均对卵母细胞成熟事件具有适应性和响应性。总之，我们提供了一种可靠地测量ΔΨm的新方法，这为卵母细胞和早期胚胎中线粒体功能的时空调控提供了新的思路。这些发现表明，线粒体活性在全局和局部水平上均对卵母细胞成熟事件具有适应性和响应性。总之，我们提供了一种可靠地测量ΔΨm的新方法，这为卵母细胞和早期胚胎中线粒体功能的时空调控提供了新的思路。