Maternal metabolic status and in-vitro culture conditions during embryonic genome activation deregulate the expression of energy-related genes in the bovine 16-cells embryo

Abstract

The molecular consequences of the metabolic stress caused by milk production of dairy cows in the early embryo are largely unknown. The objective was to determine the impact of dam metabolic status or in vitro culture during embryonic genome activation (EGA) on the transcriptomic profiles of bovine 16-cell stage embryos. Two days after synchronized oestrus, in vitro produced 2- to 4-cell stage embryos were endoscopically transferred in pools of 50 into the oviduct ipsilateral to the corpus luteum of lactating (LACT, n = 3) or nonlactating (i.e. dried off immediately at calving; DRY, n = 3) dairy cows. On Day 4, the oviducts were flushed to recover the embryos. Pools of five Day-2 embryos (n = 5) and Day-4 16-cell stage embryos obtained in vitro (n = 3) or from LACT or DRY cows were subjected to RNAseq. Temporally differentially expressed genes (DEG; FDR<0.05) between Day-2 and Day-4 embryos were determined considering the differences between the three conditions under which EGA occurred. Also, DEG between Day-4 embryos derived from the three conditions were identified. Functional analysis of the temporal DEG demonstrated that genes involved in ribosome, translation and oxidative phosphorylation in the mitochondria were strongly more expressed in Day-4 than Day-2 embryos. Comparison of Day-4 embryos that underwent EGA in vitro, or in LACT or DRY cows, identified DEG enriching for mitochondrial respiration and protein translation, including the mTOR pathway. In conclusion, exposure of the embryo to an unfavourable maternal metabolic status during EGA influences its transcriptome and potentially the competence for pregnancy establishment.

RNA sequencing and gene co-expression network of in vitro matured oocytes and blastocysts of buffalo

“…This method has been used to study oocyte competence ( Feuerstein et al, 2012 ; Bunel et al, 2015 ; Luo et al, 2016 ; Du et al, 2018 ; Wang et al, 2023b )⁠⁠⁠⁠⁠ and embryo competence ( Bauer et al, 2010 ; Redel et al, 2012 ; Cao et al, 2014 ; Kropp and Khatib, 2015a , 2015b ; Milazzotto et al, 2016 ; Boroviak et al, 2018 ; Sood et al; 2019 ; Li et al, 2020 ; Goel et al, 2022 )⁠⁠ across various species. Moreover, to investigate in vitro maturation ( Reyes et al, 2015 ; Gilchrist et al, 2016 ; Angel-Velez et al, 2023 )⁠⁠⁠ and in vitro embryo development⁠⁠ in mammalian ( Østrup et al, 2013 ; Xue et al, 2013 ; Graf et al, 2014 ; Jiang et al, 2015 ; Song et al, 2022 ; Rabaglino et al, 2023 )⁠.…”