Maternal metabolic stress affects in vitro embryo's transcriptom pattern

This study aims to investigate the potential implication of epigenetic mechanisms in the transmission of maternal metabolic information to the embryo, in order to better understand how maternal metabolic stress influences fertility. To do this, we exposed the oocytes of 54 cows to different environments during maturation (24 hours). The treatments include normal glucose concentration (5.5 mM), low glucose concentration (2.75 mM) and low glucose concentration with supplementation of BHB (1.8 mM). BHB is a ketone body that accumulates in circulation during clinical ketosis due to an increased rate of fat mobilization. BHB can be metabolized by the embryo in addition to acting as an epigenetic regulator. Epigenetic modifications are a potential mechanism for transmitting maternal metabolic information from the oocyte to the embryo, given their heritability. As a result, we observe normal oocyte maturation within each condition. On the other hand, we see significantly higher blastocyst rates in the BHB supplemented group compared to the low glucose group (p-value = 0.0318). By modulating the expression of several genes, some of which related to development and metabolism, glucose deprivation (low glucose) has a greater influence on the embryo transcriptome than the exposure to BHB during maturation. BHB appears to have a compensatory effect on blastocyst rates by minimizing the impact of glucose deprivation on developmental rates. This project elucidates how certain metabolic conditions, including clinical ketosis in dairy cows or obesity in women influences fertility and the health of offspring. Ovocytes are split into three groups and matured on three different media, one Control media and two stress media: Low Glucose and Low Glucose + BHB. Once mature, IVF is performed. The transcriptom of 8-days balstocystes are then extracted, sequenced and analyzed.