Development and Stem Cell Program and Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.
Applied Embryology Department, High Institute for Infertility Diagnosis and Assisted Reproductive Technologies, AL-Nahrain University, Baghdad, Iraq.
Mol Hum Reprod. 2019 Nov 30;25(11):695-705. doi: 10.1093/molehr/gaz055.
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.
线粒体是高度动态的细胞器，其分布、结构和功能影响着广泛的细胞功能。线粒体膜电位（∆Ψm）是线粒体活性的指标，在 ATP 产生、氧化还原平衡、信号转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于线粒体功能，但对于卵母细胞成熟过程中∆Ψm 的时空方面知之甚少。一个例外是，以前使用∆Ψm 指示剂 JC-1 的发现报告说，皮质中的线粒体相对于细胞质的其余部分表现出优先增加的∆Ψm。使用活细胞成像和一种新的比率测量方法来测量小鼠卵母细胞中的∆Ψm，我们发现∆Ψm 在卵母细胞成熟过程中增加，并且靠近第一次减数分裂纺锤体的线粒体与细胞质的其他区域相比，∆Ψm 增加。我们没有证据表明卵母细胞皮质中的∆Ψm 升高。这些发现表明，线粒体活性是适应性的，并对卵母细胞成熟过程中的全局和局部事件做出反应。总之，我们提供了一种可靠测量∆Ψm 的新方法，为卵母细胞和早期胚胎中线粒体功能的时空调节提供了新的见解。
