Transcriptomic signature to oxidative stress exposure at the time of embryonic genome activation in bovine blastocysts

Abstract

In order to understand how in vitro culture affects embryonic quality, we analyzed survival and global gene expression in bovine blastocysts after exposure to increased oxidative stress conditions. Two pro-oxidant agents, one that acts extracellularly by promoting reactive oxygen species (ROS) production (0.01 mM 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) or another that acts intracellularly by inhibiting glutathione synthesis (0.4 mM buthionine sulfoximine [BSO]) were added separately to in vitro culture media from Day 3 (8-16-cell stage) onward. Transcriptomic analysis was then performed on resulting Day-7 blastocysts. In the literature, these two pro-oxidant conditions were shown to induce delayed degeneration in a proportion of Day-8 blastocysts. In our experiment, no morphological difference was visible, but AAPH tended to decrease the blastocyst rate while BSO significantly reduced it, indicating a differential impact on the surviving population. At the transcriptomic level, blastocysts that survived either pro-oxidant exposure showed oxidative stress and an inflammatory response (ARRB2), although AAPH induced higher disturbances in cellular homeostasis (SERPINE1). Functional genomics of the BSO profile, however, identified differential expression of genes related to glycine metabolism and energy metabolism (TPI1). These differential features might be indicative of pre-degenerative blastocysts (IGFBP7) in the AAPH population whereas BSO exposure would select the most viable individuals (TKDP1). Together, these results illustrate how oxidative disruption of pre-attachment development is associated with systematic up-regulation of several metabolic markers. Moreover, it indicates that a better capacity to survive anti-oxidant depletion may allow for the survival of blastocysts with a quieter metabolism after compaction.

Energy and lipid metabolism gene expression of D18 embryos in dairy cows is related to dam physiological status

“…Interestingly, we found this later pathway upregulated in GH vs. ELC conceptuses (upregulation of PGD and TKT genes). The exposure of the zygote to high levels of glucose was associated with an increase in gene expression associated with oxidative stress (12,13). The fact that SLC2A1 is overexpressed in the EET of D18 conceptuses from heifers in our experiment could thus indicate a state of higher metabolic activity but also of higher oxidative stress.…”

Transcriptome of the GSH-Depleted Lens Reveals Changes in Detoxification and EMT Signaling Genes, Transport Systems, and Lipid Homeostasis

“…68 This study found that of the 231 gene changes in AAPH-treated blastocysts and 481 gene changes in BSO-treated blastocysts, 69 of the gene changes overlapped. This demonstrates that GSH-depletion causes many changes outside of traditional oxidative stress responses and may not induce many expected oxidative stress responses, as we have shown in this study.…”

Exposure of bovine oocytes and embryos to elevated non-esterified fatty acid concentrations: integration of epigenetic and transcriptomic signatures in resultant blastocysts

“…Notwithstanding these limitations, the blastocyst is an interesting target to investigate. Transcriptome studies have extensively shown how early embryos interact with their immediate microenvironment [31, 57, 58]. Epigenetic reprogramming at this stage puts the embryo at risk of programming errors with potential long-term consequences due to an adverse environment [23].…”