Application of extracellular flux analysis for determining mitochondrial function in mammalian oocytes and early embryos

Muller, Bethany; Lewis, Niamh; Adeniyi, Tope; Leese, Henry J; Brison, Daniel R; Sturmey, Roger G.

Abstract

Mitochondria provide the major source of ATP for mammalian oocyte maturation and early embryo development. Oxygen Consumption Rate (OCR) is an established measure of mitochondrial function. OCR by mammalian oocytes and embryos has generally been restricted to overall uptake and detailed understanding of the components of OCR dedicated to specific molecular events remains lacking. Here, extracellular flux analysis (EFA) was applied to small groups of bovine, equine, mouse and human oocytes and bovine early embryos to measure OCR and its components. Using EFA, we report the changes in mitochondrial activity during the processes of oocyte maturation, fertilisation, and pre-implantation development to blastocyst stage in response to physiological demands in mammalian embryos. Crucially, we describe the real time partitioning of overall OCR to spare capacity, proton leak, non-mitochondrial and coupled respiration – showing that while activity changes over the course of development in response to physiological demand, the overall efficiency is unchanged. EFA is shown to be able to measure mitochondrial function in small groups of mammalian oocytes and embryos in a manner which is robust, rapid and easy to use. EFA is non-invasive and allows real-time determination of the impact of compounds on OCR, facilitating an assessment of the components of mitochondrial activity. This provides proof-of-concept for EFA as an accessible system with which to study mammalian oocyte and embryo metabolism.

Citation

Muller, B., Lewis, N., Adeniyi, T., Leese, H. J., Brison, D. R., & Sturmey, R. G. (2019). Application of extracellular flux analysis for determining mitochondrial function in mammalian oocytes and early embryos. Scientific reports, 9(1), Article 16778. https://doi.org/10.1038/s41598-019-53066-9

• Journal Article Type: Article
• Acceptance Date: Oct 12, 2019
• Online Publication Date: Nov 14, 2019
• Publication Date: Dec 1, 2019
• Deposit Date: Oct 14, 2019
• Publicly Available Date: Oct 15, 2019
• Journal: Scientific Reports
• Print ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Issue: 1
• Article Number: 16778
• DOI: https://doi.org/10.1038/s41598-019-53066-9
• Public URL: https://hull-repository.worktribe.com/output/2927095
• Publisher URL: https://www.nature.com/articles/s41598-019-53066-9
• Additional Information: A pre-review version of this article was lodged on BioRvix and was deposited on WT Ref 2927095
• Contract Date: Nov 20, 2019