School of Agriculture and Food Science, University College Dublin, Dublin, Ireland.
Division of Reproduction and Early Development, School of Medicine, University of Leeds, Leeds, United Kingdom.
PLoS One. 2023 Aug 25;18(8):e0290689. doi: 10.1371/journal.pone.0290689. eCollection 2023.
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.
奶牛早期产奶导致的代谢应激对早期胚胎的分子影响在很大程度上尚不清楚。本研究旨在确定母体代谢状态或胚胎基因组激活（EGA）期间的体外培养对牛 16 细胞期胚胎转录组谱的影响。在同步发情后 2 天，通过内窥镜将体外生产的 2-4 细胞期胚胎以 50 个胚胎为一 pooling 转移到产奶（LACT，n = 3）或非产奶（即在产犊时立即干奶；DRY，n = 3）奶牛的同侧输卵管中。在第 4 天，冲洗输卵管以回收胚胎。将 5 个 Day-2 胚胎的 pooling（n = 5）和体外获得的 Day-4 16 细胞期胚胎的 pooling（n = 3）或来自 LACT 或 DRY 奶牛的 pooling 进行 RNAseq。考虑到 EGA 发生的三种条件之间的差异，确定了 Day-2 和 Day-4 胚胎之间的差异表达基因（DEG；FDR<0.05）。还鉴定了来自三种条件的 Day-4 胚胎之间的 DEG。对时间 DEG 的功能分析表明，与 Day-2 胚胎相比，参与核糖体、翻译和线粒体氧化磷酸化的基因在 Day-4 胚胎中表达更强。比较在体外、LACT 或 DRY 奶牛中进行 EGA 的 Day-4 胚胎，鉴定了富含线粒体呼吸和蛋白质翻译的 DEG，包括 mTOR 途径。总之，胚胎在 EGA 期间暴露于不利的母体代谢状态会影响其转录组，并可能影响妊娠建立的能力。
