Novel aspects of mitochondrial biology in early embryos

Muller, Bethany

Medicine
May 2019

Thesis or dissertation


Rights
© 2019 Bethany Muller. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Abstract

Mitochondria play an essential role in early development through facilitating the production of energy required to undergo key physiological processes. Mitochondrial function in oocytes and embryos has been associated with viability and reproductive outcomes, and is increasingly becoming a focus as a target for assisted reproduction technology. A number of tools have been applied to measure mitochondrial activity, however each have limitations. Here, we apply Seahorse XFp to mammalian oocytes and embryos for the first time. Seahorse XFp allows real-time measurement of mitochondrial activity in an automated and high-throughput manner and, coupled with mitochondrial inhibitors, can be used to gain insight on the parameters of mitochondrial function. This tool was used to carry out an investigation on physiological embryo function, revealing values of OCR similar to those generated from established techniques. Expected trends of cumulus increasing OCR, increased capacity following in vitro fertilisation and an increase in OCR between cleavage and blastocyst stage were observed. Seahorse XFp was then applied alongside metabolic tools to measure glycolytic activity and amino acid turnover to investigate clinically relevant interventions. Application of cytoskeletal inhibitors as used during mitochondrial replacement therapy (MRT) resulted in no major changes to gross metabolic measures. However, amino acid metabolism did show alterations at both cleavage and blastocyst stages, demonstrating a legacy effect that warrants further work to support safety of MRT. Exposure to mitochondrial modulator CoQ10 during in vitro maturation has previously been shown to alter metabolic function in oocytes, and we expanded this finding to show that metabolic changes were observed in embryos. CoQ10 exposure during in vitro culture, on the other hand, was shown to require further optimization. These data contribute to the emerging data set regarding mitochondrial modulation in ART and importantly present a tool which has the potential to be widely applied in reproductive biology.

Publisher
Hull York Medical School, The University of Hull and The University of York
Supervisor
Sturmey, Roger
Sponsor (Organisation)
University of Hull
Qualification level
Doctoral
Qualification name
PhD
Language
English
Extent
2 MB
Identifier
hull:17357
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